[0001] The invention generally relates to a method for coating a vehicle body, the method
having the features as stated in the generic part of claim 1. Further, the invention
generally relates to a coating apparatus having the features as stated in the generic
part of claim 27.
[0002] Coating substrates such as vehicle bodies are coated during a series of steps constituting
a coating line while the vehicle bodies are being conveyed with hangers or carriages.
The coating line involves at least a spraying step for spraying an intermediate coating
or a top coating and a drying step for drying the coating sprayed on the vehicle body.
The paint on the coating substrate is generally sprayed with a spray gun. The spraying
is also effected from a transverse direction on a surface of the vehicle body extending
in a vertical direction. The spraying of the paint in the transverse direction allows
a coating to be formed in a predetermined film thickness with accuracy.
[0003] The degree of evenness on the coated surface is determined as one of standards evaluating
the quality of the coated surface. The degree of evenness gets higher as irregularities
in the coated surface are smaller thus leading to a higher quality. It is known that
a film thickness of a coating sprayed on a coating substrate must be thicker if a
higher degree of evenness is desired.
[0004] However, when a paint is sprayed on a surface to be coated the paint has a tendency
to sag on the coated surface and such sagging impairs the quality of the coating.
Sagging may be caused to occur when the paint sprayed flows downwardly or droops by
gravity, whereby sagging is more likely to occur when the film thickness of the paint
sprayed gets thicker. As sagging occurs by the influence of gravity, it is likely
to occur on a coated surface extending in the downward and upward direction, i.e.
extending vertically. On a surface of the coating substrate extending in the horizontal
direction, or a transverse surface, no problems are caused in regard to sagging and,
therefore, a thicker film can be formed thereupon than on a vertical surface. If the
film thickness of a coating formed on the transverse surface is as thick as that of
a coating formed on a vertical surface, the former will provide a higher degree of
evenness than the latter because the paint on the transverse surface is caused to
flow only to such an extent that it does not cause sagging.
[0005] Heretofore, attempts have been made to prevent a paint coating from sagging and at
the same time to provide a degree of evenness as high as possible on the coated surface
by using a paint with a possibly lower degree of flowability. A sagging threshold
film thickness of a paint coating which causes no sagging is known to be as thick
as 40 µm for a thermosetting paint although the sagging threshold value varies with
the different kinds of paints. Accordingly, in instances where a thermosetting paint
is employed, the film thickness to be produced on the vehicle body in the spraying
step is determined such that no sagging is caused to occur in the early stages of
the drying step. Thus, in order to form a coated surface with a higher degree of evenness,
it is necessary in conventional spraying procedures to repeatedly effect the spraying.
[0006] A method for coating a vehicle body including the method steps stated in the generic
part of claim 1 has been disclosed in US-A 26 58 008. This method provides spraying
of the paint onto the vehicle body, and even dipping of the vehicle body into a bath
of paint, in an excess amount of paint while the vehicle body is rotated about a horizontal
axis. The excess amount of paint is such that, during rotation of the vehicle body,
the paint will flow on the surfaces of the vehicle body thereby getting into all the
crevices thereof and can drip off back into the bath again. After the excess amount
of paint has dripped off and the paint has been distributed over the surfaces by flowing,
the vehicle body is conveyed into a drying station wherein the paint film is baked
at an elevated temperature. Applying the paint to such an excess that the paint can
readily flow upon the surfaces of the vehicle body and drip off therefrom will cause
flowing traces which cannot be removed even if the vehicle body is rotated during
the baking step. Therefore it will be difficult to obtain a high-gloss finish of the
paint of the vehicle body after drying.
[0007] In the EP-A 195 510 a method for coating articles by spraying paint upon them has
been disclosed wherein the articles are supported on a table which is rotating about
a vertical axis. However, rotation about a vertical axis cannot influence the sagging
tendency of the paint on account of gravity, and therefore sagging can only be prevented
by distributing the paint in a film thickness below the threshold film thickness.
[0008] From JP-U2228/1976 it is known to coat articles like fences, window frames and the
like by dipping same into a bath of paint and, after removing same from the bath,
rotating the articles about a horizontal axis in order to drip off surplus paint.
However, since dipping of articles into a bath of paint in any case will provide paint
upon the surfaces of the article to such an extent that the paint will flow and drip
off, flowing or sagging traces cannot be entirly prevented even by rotation during
the drying step. Thus a high-gloss surface cannot be obtained.
[0009] From JP-A 67332/1973 and US-A 40 92 953 it is known to coat glass bodies, e.g. glass
bottles, with a protective coating of a plastics material in order to protect the
bottles from breaking. To this end the bottles are rotated about a horizontal axis
and thereby the liquid plastics material is sprayed upon them by spray nozzles. Rotation
is continued in the curing step of the plastics material, which may be carried out
under elevated temperature in a drying oven. While rotation in these known methods
is intended to provide a uniform thickness of the coating film, a high-gloss polish
similar to that which is desired on vehicle bodies is not intended at all by the protective
layer of plastics material. Therefore no particular care is taken to prevent any local
sagging in these known methods.
[0010] It is a basic object of the present invention to provide a method for coating a vehicle
body in a coating line the method capable of overcoming the problem of sagging of
a paint sprayed so as to form a coated surface with a higher degree of evenness compared
with a coating having the same film thickness and obtained by prior art techniques.
[0011] A further basic object is to provide a coating apparatus suitable for the coating
method according to the present invention and having particularly advantages in the
coating line from the non-explosive point of view.
[0012] In order to achieve these objects, a coating method is basically proposed as stated
in the characterizing part of claim 1.
[0013] In addition, for carrying out this method, a coating apparatus is proposed as stated
in the characterizing portion of claim 26.
[0014] According to the invention use is made of a paint which is exclusively or particularly
flowable at the ambient temperature of the baking step within the drying station,
and the vehicle body with all the paint coated thereon is rotated in the baking station.
[0015] The coating method according to the invention is basically designed so as to relatively
alter the direction of gravity acting on a paint sprayed on the vehicle body, thus
providing a coated surface having a higher degree of evenness by utilizing the flowability
of the paint peculiar in nature. More specifically, the coating method according to
the invention comprises the spraying step in which the paint is sprayed to form a
coating of a film thickness higher than the threshold film thickness in excess of
which the paint will sag at least on a surface extending vertically. Further the method
comprises the drying step including a setting step and a baking step whereby the vehicle
body is rotated at least in the baking step about the horizontal axis until the paint
sprayed thereon has set to such a state that no sagging will occure any longer.
[0016] The coating method according to the present invention provides a coat of a paint
with a film thickness much thicker than coats formed by conventional coating methods
and a coated surface with a degree of evenness exceeding by far and higher than a
limit imposed on conventional coating methods.
[0017] In accordance with the present invention, a coated surface with smaller irregularities
and higher degree of evenness than the superior in quality to a coated surface coated
in conventional manner can be obtained utilizing a flowability of the paint even if
film thicknesses were identical to each other.
[0018] In order to obtain a coated surface with a degree of evenness equal to a degree of
evenness on a surface coated by conventional coating procedures, a film thickness
of the former coated surface can be rendered thinner than the latter coated surface,
thus reducing an amount of the paint to be coated.
[0019] The coating method according to the present invention permits a paint to be sprayed
or coated plurally, for example, two or three times, to form a coat with a predetermined
film thickness. When a surface area to be coated is wide, a considerable long period
of time is required until the whole surface area is sprayed thoroughly. In this case,
the paint may be preferably sprayed separately. For example, the paint may be sprayed
first in an amount accounting for about two-third of a sagging threshold value and
then in an amount exceeding the sagging threshold value.
[0020] In instances where a paint to be sprayed has an extremely high flowability and it
should be coated in an extremely great film thickness, sags are likely to occur immediately
after the completion of spraying. In this case, a coated substrate may be caused to
rotate at the later stage of the spraying step.
[0021] The spraying of a paint on coating substrates such as vehicle bodies may be effected
in conventional manner such as by the electrostatic coating method.
[0022] The coating apparatus according to the present invention is used to rotate the coating
substrates such as vehicle bodies subject to the coating method according thereto.
The coating apparatus basically utilizes a carriage to be conveyed along a coating
line, which contains supporting means for supporting the coating substrate loaded
on the carriage rotatively about the horizontal axis of rotation. In order to drive
the rotation of the coated substrate supported by the supporting means, a spring may
be employed as one embodiment. The carriage is provided with the spring and a transmitting
mechanism for transmitting the restoring force stored by the spring as a rotating
force to the coating substrate. On a passage of conveying the carriages is mounted
force storing means for storing the restoring force again on the spring from which
the restoring force has once been released. Thus this arrangement permits a rotation
of the coating substrate by utilizing the restoring force of the the spring, thereby
causing no problems at all with explosion.
[0023] The present invention has the advantage that a mechanism for rotating the coating
substrates is rendered less expensive in manufacturing and operating costs because
the springs are employed as sources of driving the rotation.
[0024] As another embodiment for rotating the coating substrate supported rotatively on
a carriage, there may be used a displacement of the carriage against the conveying
rails. For this purpose, the carriage is provided with a converting mechanism for
converting the displacement of the carriage against the conveying rails into a rotating
force. Such a mechanism may contain a chain or a rack disposed along the conveying
rails and a sprocket or a pinion supported rotatively to the carriage and engaged
with the chain or the rack. The sprocket or the pinion is in turn connected to the
coating substrate. This construction renders an overall structure of a coating apparatus
simple and manufacturing and operating costs less expensive.
[0025] The other objects and advantages of the present invention will become apparent in
the course of description of the specification by way of embodiment with reference
to the attached drawings.
BRIEF DESCRIPTTION OF THE DRAWINGS
[0026]
FIG. 1 is a flow chart of an overall step illustrating one example of the coating
method according to the present invention;
FIG. 2 is a diagrammatical view illustrating variations in states of a rotating vehicle
body;
FIG. 3 is a graph showing the relationships of speeds of paint sagging and sagging
threshold values vs. film thicknesses of coats and setting/baking limes:
FIG. 4 is a graph showing the relationships of image sharpness degrees vs. overcoat
film thicknesses and rotation degrees of a coating substrate;
FIG. 5 is a side view illustrating one example of a carriage for conveying a vehicle
body and a rotation device or jig;
FIG. 6 is a plane view of the carriage and the rotation device in FIG. 5;
FIG. 7 is a left side view of FIG. 5;
FIG. 8 is a perspective view of a front side portion of the rotation device;
FIG. 9 is a front view illustrating the essential part of a spring for continuous
rotation;
FIG. 10 is a partially cross-sectional plane view of the spring in FIG. 9 as seen
from the top;
FIG. 11 is a diagrammatical plane view of an acceleration mechanism as seen from the
axial direction;
FIG. 12 is a partially cross-sectional plane view, as taken along the line X-X, of
the acceleration mechanism in FIG. 11;
FIG. 13 is a diagrammatical side view illustrating the essential part of a ratchet
mechanism;
FIG. 14 is a plane view illustrating the essential part of the ratchet mechanism in
FIG. 13 for an automatic operation;
FIG. 15 is a partially cross-sectional plane view illustrating a spring for the start-up
operation;
FIG. 16 is a partially cross-sectional plane view, taken along the line Y-Y line,
of the spring in FIG. 15;
FIGS. 17 and 18 are each a partially cross-sectional plane view of another example
of a spring for the start-up operation;
FIG. 19 is a partially cross-sectional plane view illustrating one example of a stopper
mechanism for stopping the vehicle body at a predetermined rotational position;
FIG. 20 is a cross-sectional view of a stopper rod to be used for the stopper mechanism
in FIG. 19;
FIGS. 21 and 22 are a front view and a perspective view, respectively, illustrating
another example of a stopper mechanism for stopping the vehicle body at a predetermined
rotational position;
FIGS. 23 and 24 are a front view and a side view, respectively, illustrating one example
of a loading/unloading apparatus for loading or unloading the vehicle body on the
carriage;
FIG. 25 is a diagrammatical plane view showing the locus of the conveying carriages;
FIGS. 26 and 27 are a perspective view and a side view illustrating one example of
a force storing apparatus for applying a restoring force to the spring for the rotation;
FIG. 28 is a cross-sectional side view illustrating another example of a connection
portion between the rotation device and the carriage;
FIG. 29 is a cross-sectional view taken along the line X29-X29 in FIG. 28;
FIG. 30 is a plane view of FIG. 28;
FIG. 31 is a cross-sectional view taken along the line X31-X31 in FIG. 28;
FIG. 32 is a cross-sectional view taken along the line X32-X32 in FIG. 28;
FIG. 33 is a plane view of FIG. 32;
FIG. 34 is a diagrammatical perspective view illustrating a variatnt in a driving
unit;
FIG. 35 is a front view illustrating one example of a speed governing mechanism;
FIG. 36 is a right side view of FIG. 35;
FIG. 37 to FIG. 40 are each a plane view illustrating an action of the speed governing
mechanism;
FIG. 41 is a diagrammatical perspective view illustrating a variant in a driving unit;
FIG. 42 is a partially cross-sectional side view illustrating one example of a torque
switching means;
FIG. 43 is a perspective view illustrating an example of connection of the rotation
device shown in FIGS. 28 to 33 to the front portion of the vehicle body;
FIG. 44 is a perspective view illustrating an example of connection of the rotation
device shown in FIGS. 28 to 33 to the rear portion of the vehicle body;
FIG. 45 is a side view illustrating another example of a carriage with a rotation
device for rotating a coating substrate;
FIG. 46 is a partially cut-away front view illustrating the essential part of a converting
mechanism in FIG. 45;
FIG. 47 is a cross-sectional view taken along the line X47-X47 in FIG. 46;
FIG. 48 is a graph showing the relationships of speeds of sagging and temperatures
on a coating substrate vs. film thicknesses and times; and
FIG. 49 is a graph showing the relationships of speeds of sagging and temperatures
on a coating substrate vs. film thicknesses and times elapsing for setting and baking.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] The present invention will be described more in detail by way of embodiments with
reference to the drawings attached hereto. It is to be understood herein that the
following description should be interpreted as illustrative and not limiting the present
invention in any means.
Outline of Overcoating Step:
[0028] FIG. 1 shows an outline of an overcoating step of coating a top coat on a vehicle
body W. In FIG. 1, P1 to P7, inclusive, denote each of the steps constituting the
overcoating step. It is to be noted here that, although the following embodiment will
take the overcoating step as an example, the present invention is applicable to any
other coating step and apparatus.
[0029] A vehicle body W is coated first with an undercoat by means of the electrodeposition
coating method and then with an intermediate coat in conventional manner. The vehicle
body W is then loaded on a carriage D and conveyed to a preparation step P1. The carriage
D is provided with a rotation driving unit to rotate the vehicle body W utilizing
the restoring force of a spring, as will be described in more detail hereinafter.
[0030] A preparation step P1 is to clean the vehicle body W prior to the spraying of a top
coat by removing foreign material such as dirt by air blow or vacuum suction.
[0031] A spraying step P2 is to spray a top coat - a thermosetting paint in this embodiment
- on the vehicle body W conveyed from the preparation step P1.
[0032] The sprayed top coat is dried and baked in a setting step P3 and a baking step P4.
In the setting and baking steps P3 and P4, respectively, the vehicle body W is rotated
using the restoring force of the spring in such a manner as will be described hereinafter.
[0033] The vehicle body W so baked in the baking step P4 is then conveyed to an unloading
step P5 where the vehicle body W is unloaded from the carriage D. The vehicle body
W may be reloaded on a carriage and conveyed to an assembly line, and the empty carriage
D is conveyed to a rewinding step P6. In the rewinding step P6, an exterior force
is applied to the spring as a source for driving a rotation to store the restoring
source therewithin. The carriage D having the spring with the restoring force is then
conveyed to a loading step P7.
[0034] In the loading step P7, such carriage D is loaded with a vehicle body W that had
been coated with an intermediate coat in the previous steps. The vehicle body W is
then conveyed to the preparation step P1 and the following steps constituting the
overcoating step as have been described above. The carriage D is designed to circulate
the overcoating step starting from the preparation step P1 and ending with the loading
step P7.
Removal of Foreign Materials:
[0035] Foreign materials such as dirts may be removed in the preparation step P1 as the
vehicle body W is rotated about the horizontal axis
1 as shown in FIG. 2. For instance, the vehicle body W is first rotated to the position
(a) in FIG. 2 and suspended at that position to clean it by removing the foreign materials.
The carriage D may then be operated to rotate the vehicle body W to the position (b)
and suspended at that position to do cleaning work. This operation may be likewise
repeated to rotate the vehicle body W continuously or intermittently from the position
(b) through (c), (d), (e), (f), (g) and (h) to the position (i). And it is a matter
of course that the rotation of the vehicle body W may be reversed at any position
to the original position (a).
[0036] The rotation of the vehicle body W in the preparation step P1 permits removal of
such foreign materials as adhering to corner portions inside the roof panel thereof
or closed sections of side sills or as being unlikely to be thoroughly removed therefrom
unless the vehicle body W is rotated to cause them to fall down.
Spraying and Drying of Top Coat:
[0037] In the spraying step P2, the vehicle body W is sprayed with a top coat or overcoat
in an amount so as to allow a film thickness of the top coat to exceed a sagging threshold
value, namely, a maximum film thickness of the coat that does not cause sags. Conventional
thermosetting paints usually have a sagging threshold value of about 40 µm; however,
in the spraying step P2, the top coat is sprayed on the vehicle body W in an amount
to form a film thickness, for example, as thick as 65 µm, that exceeds its sagging
threshold value.
[0038] The vehicle body W with the top coat so sprayed is immediately conveyed from the
spraying step P2 to the setting step P3. This setting step P3 is so constructed, as
shown in FIG. 2(a) to (i), inclusive, that the vehicle body W is rotated in a horizontal
direction, viz., about the rotational axis
l extending in the horizontal direction. In this embodiment, the rotational axis
l is designed to extend in the front and rear direction of the vehicle body W. Although
ambient temperatures used in the setting step P3 are room temperature in this embodiment,
they may be set in an appropriate range of temperatures, for instance, from 40 °C
to 60 °C, lower than temperatures used in the following baking step P4. It is to be
noted that the setting step P3 is to cause low-boiling components of the top coat
to evaporate prior to the baking step P4, thereby preventing such low-boiling overcoat
components from evaporating rapidly in the baking step P4 and consequently causing
no pinholes on the top coat surfaces.
[0039] In the baking step P4, the top coat on the vehicle body W is baked at ambient temperatures,
for example, as high as 140°C. Like the setting step P3, this baking step P4 is conducted
while the vehicle body W is rotated in the horizontal direction as shown in the squence
of FIG. 2(a) to (i).
[0040] The rotation of the vehicle body W in the horizontal direction as in the respective
setting and baking steps P3 and P4 permits a coat to be dried without causing sags
even if a paint is sprayed to form a film thickness exceeding a sagging threshold
value. This can provide a coat surface of high quality with such a high degree of
evenness as conventional coating methods could not provide.
Relationships of Film Thickness with Sagging Threshold Value And of Degree of Evenness
with Horizontal Rotation:
[0041] FIG. 3 shows influences of film thicknesses of a thermosetting paint over sagging
threshold values. FIG. 3 takes film thickness of 40µm, 53 µm and 65 µm as examples.
In each case, a peak of sags has been recognized each at the early stages of both
the setting step P3 and the baking step P4. A sagging threshold value is usually defined
as a value at the time when sags are caused to occur at a rate ranging from 1 to 2
mm per minute. It is understood that, if sags would occur at a rate of 2 mm or more
per minute when visually observed, coat surfaces are caused to be not good. By conventional
methods using a conventional paint, the maximum film thickness that had ever obtained
at a range below a sagging threshold value was as thin as about 40 µm.
[0042] FIG. 4 shows influences of horizontal rotations of the vehicle body W on degrees
of evenness of top coats. In FIG. 4, reference symbol A denotes a state of a top coat
coated using a conventional coating method where the vehicle body W is not rotated.
Reference symbol B denotes a state of a top coat obtained by rotating the vehicle
body W in a clockwise direction at 90 ° and then reversing it in a counterclockwise
direction to the original position, namely, rotating it from the position of FIG.
2(a) through (b) to (c) and then reversing it from the position (c) through (b) back
to (a). Reference symbol C denotes a state of a top coat obtained by rotating the
vehicle body W at 135 ° and then reversing it to the original position, namely, rotating
it from the position of FIG. 2(a) through (b) and (c) to (d) and then returning it
from the position of FIG. 2(d) through (c) and (b) back to the original position (a).
Reference symbol D denotes a state of a top coat obtained by rotating the vehicle
body W at 180°C from the position of FIG. 2(a) through (b), (c) and (d) to (e) and
then back to the original position of FIG. 2(a) through (d), (c) and (b) from (e).
In FIG. 4, reference symbol E denotes a state of an overcoat obtained when the vehicle
body W is rotated around in one way from the original position of FIG. 2(a) through
(b), (c), (d), (e), (f), (g) and (h) back again to the original position of FIG. 2(i).
[0043] The vehicle body W may be rotated in one direction or rotated in one direction after
another, in a continuous manner or in such an intermittent manner that it is rotated
to a predetermined position and then suspended at that position. This operation may
be repeated.
[0044] In order to control a paint sagging, the vehicle body W may be preferably rotated
so as to return a coated surface from a vertical state to a horizontal state until
the paint coated thereon flows to a length of 1 to 2 mm.
[0045] As the vehicle body W is rotated, a centrifugal force works on the sprayed coat,
thus causing the coat to be sagged. Such a paint sagging is caused when a test piece
of the coating substrate is rotated at 180° and then reversed at 180° for 0.25 second
at a diameter of 30 cm, so that a speed of rotating the coating substrate is less
than the speed caused the paint sagging on the test piece. Accordingly, a speed for
rotating the vehicle body W may be 380 cm per second or less at the top end portion
thereof, thus preventing paint sags from occurring by way of a centrifugal force,
and the speed may not necessarily be constant. As the rotating radius of the coating
substrate gets larger, the speed of rotation rotating radius of the coating substrate
gets larger, the speed of rotation gets slower.
[0046] From the above, as shown in FIG. 3 a time required to cause the vehicle body W to
be reversed at 180° or rotated at 90 ° up to the horizontal state may be preferably
set from 0.25 second to 10 minutes. The speed of rotation may preferably from 6 r.p.m.
to 600 r.p.m.
[0047] As is apparent from the results of FIG. 4, if a film thickness of a coat is identical
to each other, a higher degree of evenness of the top coat is achieved when the vehicle
body W is rotated, as shown by reference symbols B, C, D and E in FIG. 4, than when
it is not rotated, as shown by reference symbol A in FIG. 4. It is also noted that,
in instances where the vehicle body W is rotated, the round rotation of the vehicle
body W in one direction by 360° is preferred to provide a coat with a higher degree
of evenness. It is further to be noted that, in instances where the vehicle body W
is not rotated as in conventional manner, a film thickness of a coat is caused to
be restricted to a certain value, thus leading to a limit on a degree of evenness.
[0048] A combination of the rotation of the vehicle body W in one direction with the subsequent
reversal of the rotation thereof in the opposite direction may be preferably conducted
in order to prevent the sprayed paint from collecting in irregular film thicknesses
locally at corner portions formed by intersecting the surfaces extending in the rotational
axis
l. This operation permits a uniform coat on the surface of the vehicle body W.
[0049] To account for a degree of evenness on a coated surface, there is used herein an
image sharpness degree that assigns a mirror surface on a black glass an I. G. (image
gross) score of 100. By comparison, a film thickness of 65 µm, when formed by rotating
the vehicle body W at 360, gets an 87 on the I.G. scale (the lower limit at a PGD
value being 1.0), which means that the coated surface has 85% of the I.G. score on
the mirror surface of the black glass. A film thickness of 40 µm scores a 58 (the
lower limit at a PGD value being 0.7) when formed without rotation of the vehicle
body W while a 68 (the lower limit at a PGD value being 0.8) when formed by rotating
it at 360. In the above definition, a PGD values stands for a degree of identification
of a reflected image and is rated so as to be decreased from 1.0 as a degree of evenness
gets lower.
[0050] The data shown in FIGS. 3 and 4 were obtained under the following test conditions:
a) Paint: melamine alkid (black)
Viscosity; 22 seconds/20 °C (measured by Ford Cup #4)
b) Film coater: Minibell (16,000r.p.m.)
Shaping air: 2.0 kg./cm²
c) Spraying amounts (two times):
First time: 100 cc/minute
Second time: 150 - 200 cc/minute
d) Setting time/temperature: 10 minutes/room temperature
e) Baking temperature/time: 140 °C/25 minutes
f) Degree of undercoat evenness: 0.6 (PGD value) (intermediate coat over PE tape)
g) Time period for rotation and reversal:
10 minutes (for the setting step)
10 minutes (for the baking step)
h) Material to be coated: The side surfaces of a square pipe with a 30 cm side are
coated and supported at its center rotatively.
i) Rotational speed of the material to be coated: 6, 30 and 60 r.p.m. (No difference
has in fact recognized at all.)
Carriage:
[0051] The carriage D is provided with a mechanism for rotating the vehicle body W loaded
thereon.
[0052] Referring to FIG. 5, the carriage D is shown to include a base 21 and wheels, generally
referred to as 22, running on rails 23, 23. From the base 21 extend a pair of stays
24 disposed at the front and rear positions, and a traction wire 25 is fixed to the
stays 24. The traction wire 25 is designed to be driven by a motor (not shown) and
thus to drive the carriage D.
[0053] On the base 21 are mounted a pair of boxes 26 and 27 at the front the rear end portions
thereof (left and right end portions in FIG. 5). The boxes 26 and 27 are disposed
to function as support portions for supporting the vehicle body W rotatively by a
rotation device 1 as will be described more in detail hereinafter. On the tops of
the boxes 26 and 27 are disposed bearing stands 28 and 29, respectively, in a fixed
manner. A space between the pair of the boxes 26 and 27 is a supporting space 30 that
is slightly wider than the total length of the vehicle body W and supports the vehicle
body W.
Rotation Device:
[0055] Referring to FIGS. 5 and 6, the rotation device or jig 1 is shown to include a front
side portion 1F and a rear portion 1R and a reinforcing connection portion 2 for connecting
the front side portion 1F to the rear side portion 1R.
[0056] As shown in FIG. 8, the front side portion 1F of the rotation device 1 is constructed
to include a connecting portion 3 with both side portions bent in such a shape as
shown in the drawing to form a pair of front mounting portions 4F, 4F. The connection
portion 3 and the mounting portions 4F, 4F are formed from one sheet of an iron plate.
To the extension portion of the connecting portion 3 is fixed a front rotation shaft
5F in a cylindrical shape by the welding or the like. The front rotation shaft 5F
is supported rotatively by the box 26 through the bearing stand 28, and the rotation
of the front rotation shaft 5F in the horizontal direction is transmitted to the front
mounting portions 4F, 4F through the connecting portion 3. In this embodiment, the
front end portions of a pair of front side frames 11, 11 (FIG. 5) disposed at the
right and left sides of the vehicle body W are mounted detachably with bolts to the
front mounting portions 4F, 4F of the rotation device 1.
[0057] The rear side portion 1R of the rotation device 1 is constructed in substantially
the same manner as the front side portion 1F. For brevity of explanation, identical
reference symbols and numerals used in the following description denote identical
and like elements used for the front side portion 1F thereof and a description in
duplicate will be omitted herein.
[0058] It is to be noted that a pair of rear mounting portions 4R, 4R of the rear side portion
1R are constructed in such a form as being inserted tightly into rear end openings
of a pair of rear side frames 12, 12 disposed on the vehicle body W. A rear rotation
shaft 5R is supported rotatively on the box 27 through bearing stands 29, 29. The
front and rear rotation shafts 5F and 5R are designed so as to extend in a straight
line and in a horizontal direction with the vehicle body W juxtaposed therebetween,
and the axes of the front and rear rotation shafts 5F and 5R have each the rotational
center
l in common.
[0059] The reinforcing connection portion 2 of the rotation device 1 is fixed by welding
or the like to the front side portion 1F and the rear side portion 1R. In this embodiment,
the reinforcing connection portion 2 is composed of a pair of square hollow steel
bars. As shown specifically in FIG. 8, the front and rear ends of the reinforcing
connection portions 2, 2 are fixed to the front and rear side portions 1F and 1R at
positions as close as possible to the front and rear mounting portions 4F and 4R,
respectively. This construction permits the front and rear side frames 11 and 12 of
the vehicle body W to be seated partially on the reinforcing connection portions 2
and 2, thereby supporting and sharing the weight of the vehicle body W with the mounting
portions 4F and 4R. Each of the reinforcing connection portions 2, 2 is secured with
bolts to the front side frame 11 and the rear side frame 12 through brackets 6, 6
mounted at positions away from the front and rear mounting portions 4F and 4R, respectively.
This arrangement allows the vehicle body W to be mounted securedly and steady on the
rotation device 1.
Balance Weight:
[0061] The rotational axis
l of the vehicle body W is preferably set so as to coincide with and pass through the
gravitational center G obtained by a combination of the gravitational center of the
vehicle body W with the gravitational center of the rotation device 1, as shown in
FIG. 5. The coincidence of the rotational axis
l with the center of gravity G can prevent a variation in a rotation of the vehicle
body W. In instances where it is difficult to coincide the rotational axis
l with the gravitational center G, a balance weight may be placed in a rotational axis
system of the vehicle body W including the rotation device 1.
[0062] Turning now to FIG. 8, there is shown one example of a balance weight B, and it is
shown that the front side portion 1F of the rotation device 1 is provided with a first
balance weight 42 that is in turn disposed to be engageable with a first screw string
43. The both ends of the first screw string 41 are fixed to the front mounting portions
4F and 4F, respectively. To the frist balance weight 42 is fixed one end of a second
screw string 43 extending in a direction perpendicular to the horizontal direction
of the first screw string 41. A second balance weight 44 is disposed to be engageable
with the second screw string 43.
[0063] By moving the first balance weight 42 along the first screw string 41 from one position
to another in the horizontal direction, on the one hand, a position of the gravitational
center G′ of the rotational axis system comprising the vehicle body W, the rotation
device 1 and the balance weight B in the breadthwise direction can be adjusted. By
moving the second balance weight 44 along the second screw string 43 from one position
to another in the vertical direction, on the other hand, a position of the gravitational
center G′ of the rotational axis system can be adjusted in the upward or downward
direction. Furthermore, a movement of the first balance weight 42 in the circumferential
direction about the first screw string 41 permits an adjustment of the positions of
the gravitational center G′ in the upward or downward direction by the second balance
weight 44. It is noted here that the height of the first balance weight 42 is set
in advance so as to allow the center of gravity G to pass through around the height
of the first balance weight 42. This construction of the balance weight B enables
the position of the gravitational center G′ of the total rotational axis system to
be adjusted so as to coincide with and pass through the rotational center
l.
[0064] The adjustment of the gravitational center G′ of the rotational axis system may be
made at appropriate timings prior to the start-up of the rotation of the vehicle body
W. In this embodiment, this operation is carried out prior to the preparation step
P1, viz., at the time when the vehicle body W is loaded on the carriage D at the loading
step P7.
Outline of Rotation Driving:
[0065] Referring to FIGS. 5 and 6, rotation driving units K1 and K2 are disposed in the
boxes 26 and 27, respectively, as will be described more in detail hereinbelow. The
rotation driving units K1 and K2 include each a spring as a driving source and an
output shaft 31 extending toward outside the boxes 26 and 27, respectively. The output
shafts 31, 31 are designed each to transmit a power from the driving source to the
front or rear rotation shaft 5F or 5R through a transmitting mechanism 32 containing
a sprocket and a chain.
[0066] The rotation driving units K1 and K2 will be described such that the rotation driving
unit K1 is for the start-up and the rotation driving unit K2 is for the continuous
rotation.
[0067] The rotation driving unit K1 for the start-up time may provide a torque necessary
for the start-up of rotation, and the rotation driving unit K2 for the continuous
rotation may enable the rotation of the vehicle body W as much as possible within
a limited range of displacement of the spring.
Rotation Driving Unit K2:
(a) Driving Source:
[0068] Referring to FIGS. 9 and 10, it is shown that the rotation driving unit K2 comprises
a casing 61 that contains a force storing drum 62 and four of winding drums referred
to generally as 63, each drum being supported rotatively on the casing 61. The four
winding drums 63 are each constructed so as to be smaller in diameter than the force
storing drum 62 and are disposed each at an equal distance and at the angle of 90°
around the circumference of the force storing drum 62. Each of the force storing drum
62 and the four winding drums 63 is divided in axial directions with flanges into
three drum portions, referred to generally as 62a and 63a, respectively. Between each
of the drum portions 62a of the force storing drum 62 and each of the corresponding
drum portions 63a of one of the four winding drums 63 is connected and wound an extensible
thin-plate spring, referred to generally as 64. The one end 64a of the spring 64 is
fixed to each of the drum portion 62a of the force storing drum 62 and the other end
64b thereof is fixed to each of the drum portions 63a of the winding drum 63. The
same can be said of each of the drum portions 63a of the remaining drums 63. The four
springs 64 extending from each of the four winding drums 63 are superimposed in four
layers over the force storing drum 62.
[0069] The spring 64 is designed so as to remain in a free state without a restoring force
when it is wound on the drum portion 63a of the winding drum 63, on the one hand.
When the spring 64 is wound on the force storing drum 62, on the other hand, the spring
64 is forced to be brought in such a state that the springing force is stored in the
spring 64, namely, that the spring 64 generates the restoring force to go back to
the original and free state. More specifically, as the spring 64 is wound on the force
storing drum 62 and then released from the engagement with the force storing drum
62, the spring 64 is caused to generate the restoring force and rewound on the winding
drum 63, thus driving the rotation of the force storing drum 62. The force storing
drum 62 is also designed to serve as a mechanism of converting the restoring force
of the spring 64 into a force of rotation to cause the rotation of the vehicle body
W.
[0070] In this embodiment, the spring 64 is of a constant load type as capable of always
generating a constant torque of the restoring force. Thus, as a constant load is applied
to the force storing drum 62, a rotation shaft 62b of the force storing drum 62 is
rotated at a constant speed.
(b) Acceleration Mechanism L:
[0071] The rotation of the rotation shaft 62b of the force storing drum 62 is transmitted
to the output shaft 31 through an acceleration mechanism L as shown in FIGS. 11 and
12.
[0072] The acceleration mechanism L includes a casing 66 that is disposed nearby the casing
61 and constitutes part of the box 27. The casing 66 supports rotatively the output
shaft 31, and input shaft 67 and an intermediate shaft 68. The input shaft 67 is constructed
so as to receive the rotational force transmittted by the rotation shaft 62b of the
force storing drum 62. The rotation of the input shaft 67 is in turn transmitted to
the intermediate shaft 68 through a train of accelerating gears 69A and 69B, and the
rotation of the intermediate shaft 68 is further transmitted to the output shaft 31
through another train of accelerating gears 70A and 70B.
(c) Constant Load Mechanism M:
[0073] As shown again in FIG. 12, a constant load mechanism M is arranged such that the
output shaft 31 is mounted integrally with a braking drum 56 that is in abut with
a shoe 58 urged by a spring 57. This structure of the constant load mechanism M comprising
the braking drum 56, the spring 57 and the shoe 58 can produce a constant load corresponding
to the force created by urging the spring 57, thereby allowing the rotation of the
output shaft 31 based on the restoring force of the spring 64 as the source of rotation
to be rendered more constant.
(d) Ratchet Mechanism N:
[0074] Turning now to FIGS. 12 and 13, it is shown that the output shaft 31 is provided
in a secured manner with a ratchet wheel 71 outside the casing 66 constituting part
of the box 27. The ratchet wheel 71 is engageable with or disengageable from a ratched
pawl 72 that is supported pivotally about and by a pin 73 on the casing 66. The ratched
pawl 72 is disengaged from or engaged with the ratched wheel 71 by operation of a
lever 74 connected to the ratched pawl 72. A clockwise direction of the rotation of
the ratched wheel 71 transmitted from the output shaft 31, as shown in FIG. 13, is
a direction of the rotation created by the restoring force of the spring 64 as the
rotation driving source. When the ratched pawl 72 engages the ratchet wheel 71, the
rotation of the output shaft 31 produced by the restoring force of the spring 64 is
caused to stop. Accordingly, the rotation of the output shaft 31 can be kept going
or brought to a stop in an arbitrary manner, for example, by manual operation of the
level 74.
[0075] In FIG. 12, reference numeral 32a denotes a sprocket that is fixed to the output
shaft 31 and constitutes part of the transmitting mechanism 32, and reference numeral
33 denotes an engaging portion for rewinding the spring 64, as will be described hereinbelow.
(c) Ratchet Operating Mechanism O:
[0076] The ratched mechanism N may be operated to be switched automatically at a predetermined
position at which the carriage D is conveyed in such a manner as will be described
bereinbelow.
[0077] Referring now to FIG. 14, the ratchet mechanism N is shown to be disposed in the
box 27. A guide bar 75 is disposed in a secured manner along the locus of the conveyance
of the carriage D. A surface of the guide bar 75 facing the carriage D includes a
lowered surface 75a, an elevated surface 75b and a tapered surface 75c connecting
in a smooth manner between the lowered surface 75a and the elevated surface 75b.
[0078] A bracket 76 fixed to the box 27 is supported pivotably by a bell crank 77 on end
of which is connected to a base end portion of an input rod 78 and the other end of
which is connected to an output rod 79 connected in turn to the lever 74. The input
rod 78 is supported by the bracket 76 slidably in a direction perpendicular to the
direction in which the carriage D is conveyed. The bottom tip of the input rod 78
is mounted rotatively with a roller 80 as a follower, and a spring 81 is urged so
as to allow the roller 80 to always come in abut with the guide bar 75.
[0079] With this arrangement, the position of the lever 74 can be adjusted by the vertical
position of the roller 80 in abut with the guide bar 75. In this embodiment, when
the roller 80 comes in abut with the lowered surface 75a of the guide bar 75, on the
one hand, the force created by the spring 81 urged is caused to pull down the output
rod 79 so that the lever 74 connected to the output rod 79 is kept in such a state
as disengaging the ratched pawl 71 from the ratchet wheel 72, thus allowing the rotation
of the output shaft 31 to proceed. When the roller 80 comes in abut with the elevated
surface 75b of the guide bar 75, on the other hand, the force created by urging the
spring 81 acts on the input rod 78 so as for the lever 74 to cause the ratchet pawl
72 to engage the ratchet wheel 71, thereby causing the rotation of the output shaft
31 to stop.
Rotation Driving Unit K1:
[0080] The rotation driving unit K1 journaled in the box 26 will be described more in detail
with reference to FIGS. 15 and 16. In the following description, the same elements
as being used for the rotation driving unit K2 will be referred to by the same reference
symbols and numerals, and such description will be omitted herefrom for brevity of
explanation.
[0081] The arrangement for the spring 64 as the rotation driving source, the force storing
drum 62 and the winding drum 63 for the rotation driving unit K1 is substantially
the same as in the rotation driving unit K2 with the exception that the winding drum
63 and the spring 64 are disposed by only one and that the rotating force created
by the restoring force of the spring 64 is applied to the rotation device 1 through
a decelerating gear and a clutch.
[0082] A clutch plate 85a and a clutch drum 85b of a clutch 85 of a friction type are supported
rotatively in the box 26. A gear 86 fixed on the outer periphery of the clutch plate
85a is arranged to engage with a gear 87 fixed on the rotation shaft 62b of the force
storing drum 62. The gears 86 and 87 constitute a decelerating mechanism so that the
gear 86 has a diameter larger than the gear 87.
[0083] The output shaft 31 functions as a clutch output shaft disposed in the clutch drum
85b. Accordingly, when the clutch 85 is connected, the rotation of the rotation shaft
62b of the force storing drum 62 produced by the restoring force of the spring 64
is decelerated and transmitted to the output shaft 31, thereby producing a large amount
of torque necessary at the time of the start-up.
[0084] The clutch 85 is interposed for the purpose to disconnect the start-up spring 64
and the rotation device 1 immediately after the start-up of the rotation of the vehicle
body W. As the restoring force of the start-up spring 64 is decelerated and transmitted
to the output shaft 31, on the one hand, the spring 64 is designed so as to lose its
restoring force fully by allowing the spring 64 to be thoroughly rewound on the winding
drum 63, for example, as the vehicle body W is rotated nearly once. It is to be noted
here, on the other hand, that, as the spring 64 for the continuous rotation is constructed
to rotate the vehicle body W through the acceleration mechanism L, the spring 64 for
the continuous rotation having the same length as the start-up spring 64 can rotate
the vehicle body W at a number of revolutions, for example, 10 revolutions, greater
than that of the start-up spring 64. The clutch 85 is disconnected after the start-up
in order to cause the start-up spring 64 not to interfer with the rotation of the
vehicle body W.
[0085] In this embodiment, the clutch 85 is designed so as to be automatically disconnected
when the amount of the spring 64 wound thereon is detected to be nearly zero. The
amount of the spring 64 wound on the force storing drum 62 may be detected by measuring
a diameter of the drum 62 plus the spring 64 wound thereon.
[0086] As shown in FIG. 16, the rotation driving unit K1 may be provided with a mechanism
Q for detecting the amount of the spring 64 wound on the force storing drum 62. The
mechanism Q is constructed in such a manner that a lever 89 is supported rotatively
about a pin 88 in the box 26 and a spherical body 90 is mounted rotatively on the
top lip portion of the lever 89. The lever 89 is urged by a spring 91 to come always
in abut with the outer periphery of the force storing drum 62, viz., the outer circumferential
surface of the spring 64 wound on the force storing drum 62. As shown in FIG. 15,
to the lever 89 is connected a cable 92 that contains an outer tube 92a the both end
portions of which are fixed to the box 26 and an inner wire 92b disposed inside the
outer tube 92a. One end of the inner wire 92b is connected to the lever 89, and the
other end of the inner wire 92b is connected to a clutch release lever 85c.
[0087] With this arrangement, the amount of the spring 64 wound on the force storing drum
62 is decreased to reach so nearly zero that the lever 89 is displaced and causes
the clutch release lever 85c to be in turn displaced through the inner wire 92b, thus
leading to the disconnection of the clutch 85.
Variants in Start-Up Springs:
[0088] FIG. 17 illustrates an example of a variant in a start-up spring, in which a flat
spiral spring 64-1 is used as the start-up spring. The flat spiral spring 64-1 is
fixed at one end 64-1a to the force storing drum 62 and at the other end (free end)
64-1b to an engaging projection piece 95. Nearby the engaging projection piece 95
is disposed a cam piece 96 fixed to the output shaft 31. The flat spiral spring 64-1
is designed so as to have a restoring force to rotate the engaging projection piece
95 in the counterclockwise direction, as shown in FIG. 17, as it is wound on the force
storing drum 62. When the restoring force is given, the cam piece 96 is depressed
by the engaging projection piece 95 to cause the output shaft 31 to rotate the vehicle
body W. On the contrary, when the engaging projection piece 95 is rotated in the clockwise
direction as shown in FIG. 17, on the other hand, it is virtually impossible to cause
the engaging projection piece 95 to depress the cam piece 96, thus bringing the rotation
of the rotation shaft 31 to a stop.
[0089] The rewinding of the flat spiral spring 64-1 on the force storing drum 62 is effected
through a ratchet wheel 97 that is operatively coupled to the force storing drum 62
through a gear 98 engageable with the ratchet wheel 97. A ratchet pawl 99 is disposed
to engage with the ratchet wheel 97 and fixed pivotally about a pin 100, thereby permitting
movement of the ratachet wheel 97 in the clockwise direction only as shown in FIG.
17 and blocking movement in the direction opposite thereto.
[0090] The cam piece 96 is provided with a stopper hole 96a through which a stopper pin
(not shown) is inserted to engage the cam piece 96 with the box 26. When the ratchet
wheel 97 is provided with a rotational movement in the clockwise direction in FIG.
17 from the outside in a state in which the cam piece 96 is engaged with the box 26,
the flat spiral spring 64-1 is caused to be wound on the force storing drum 62 because
a rotation shaft 97a of the ratchet wheel 97 is provided with a portion corresponding
to the engaging portion 33 functioning as a portion for inputting an exterior force
for rewinding. As the stopper pin was disengaged to release the flat spiral spring
64-1, the output shaft 31 is caused to be rotated utilizing the restoring force of
the flat spiral spring 64-1 wound on the force storing drum 62. During the release,
the ratchet wheel is being rotated in a free state.
[0091] FIG. 18 shows another example of variants of start-up springs, in which the same
elements as above are represented by the same reference numerals. In this embodiment,
a flat spring 64-2 is used as a start-up spring. One end of the flat spring 64-2 is
fixed to the box 26 and the other end (free end) is disposed to face the cam piece
96 in an abuttable manner. In FIG. 18, the flat spring 64-2 represented in the solid
line demonstrates a state in which it has a restoring force while that represented
in the broken line demonstrates a state in that its restoring force is released to
the original state. The restoring force may be given the flat spring 64-2 by sliding
the flat spring 64-2 with a pin 102. The pin 102 is inserted in a rectangular hole
101 formed on the box 26 and is disposed along the rectangular hole 101 to push the
flat spring 64-2 slidably from the outside to a position at which the flat spring
64-2 engages the cam piece 96. As the flat spring 64-2 is disengaged from the cam
piece 96, the restoring force is released to the position represented in the broken
line in FIG. 18.
Stopper Mechanism R:
[0092] A stopper mechanism R is to suspend the rotation of the vehicle body W at a predetermined
rotational position and is used to stop the carriage D at a position suitable for
unload the vehicle body W in the unloading step P5.
[0093] Referring to FIG. 19, it is shown that the stopper mechanism R contains a stopper
rod 105 inserted slidably in the box 27. As shown specifically in FIG. 20, the stopper
rod 105 comprises a pair of rods 105a and 105b, and the rod 105b has a hollow portion
in which the rod 105b is inserted slidably. The rod 105b is provided at the bottom
of its hollow portion with a spring 105c that is disposed to urge the rods 105a and
105b in extending directions. At the tip portions of the rods 105a and 105b are mounted
rotatively spherical bodies 106a and 106b as followers, respectively.
[0094] The spherical body 106a at the one tip of the stopper rod 105 is disposed to come
in abut with the outer periphery of the winding drum 63, and the other spherical body
106b at the other tip of the stopper rod 105 is disposed to face the side surface
of the rotation shaft 5R of the rotation device 1. The rotation shaft 5R is provided
at the peripheral surface with an engaging hollow 107.
[0095] With this construction of the stopper mechanism R, as an amount of the spring 64
wound on the winding drum 63 gets larger as the rotation of the vehicle body W proceeds,
the increasing outer periphery of the winding drum 63 provides a growing pressure
to the spherical body 106a at the one tip of the stopper rod 105, thus causing the
spherical body 106b at the other tip of the stopper rod 105 to make an approach to
the rotation shaft 5R. As the amount of the spring 64 wound on the winding drum 63
reaches a predetermined amount, the spherical body 106b of the stopper rod 105 is
engaged with the engaging hollow 107 of the rotation shaft 5R, thereby suspending
the winding of the spring 64 and consequently the rotation of the rotation device
1 leading to the suspension of the vehicle body W at a predetermined rotational position.
[0096] In this embodiment, as the spherical body 106b is engaged with the engaging hollow
107, the vehicle body W is set to take a predetermined position as shown in FIGS.
5 and 7.
Variant in Stopper Mechanism R:
[0097] Turning now to FIGS. 21 and 21, the stopper mechanism R is shown to contain a counter
108 of the mechanical type fixed on the box 26 or 27. The counter 108 is of the type
operatively counting numbers by moving a counting bar 108b in an upward or downward
direction. For counting, the rear rotation shaft 5R of the rotation device 1 is provided
on the side surface thereof with a projection piece 109 protruding therefrom. An engaging
lever 110 is supported on the counter 108 pivotably about a pin 111.
[0098] As the counter 108 indicates a predetermined count, an operating piece 108b is disposed
to protrude upwardly to push and turn the engaging lever 110 in the counterclockwise
direction about the pin 111, as shown in FIG. 21. When the engaging lever 110 is pivoted
in the counterclockwise direction, it is then engaged with the engaging hollow 112
formed on the rear rotation shaft 5R leading to the suspension of the rotation of
the rear rotation shaft 5R and consequently the vehicle body W.
Loading/Unloading Apparatus:
[0099] A loading/unloading apparatus is to load the vehicle body W on the carriage D in
the loading step P7 and unload the vehicle body W from the carriage D in the unloading
step P5. FIGS. 23 to 25 represent one example of such an apparatus.
[0100] As shown in FIG. 25, the loading/unloading apparatus is disposed in a loading/unloading
station S1 where the locus R1 of conveyance of carriages in the coating line is approaching
to the locus R2 of conveyance of carriages or hangers in the assembly line.
[0101] The loading/unloading apparatus in this embodiment will be described as an example
in which it is used in the unloading step P5. It is thus to be understood that, although
the loading/unloading apparatus used merely in the unloading step P5 will be referred
to herein as an unloading apparatus, this may also be used generally for the loading
purposes in the loading step P7.
[0102] The unloading apparatus comprises basically a lifter 51, and the lifter 51 comprises
a pair of guide posts 52, 52 with a supporting base 53 mounted on each of the guide
posts 52, 52 in such a manner as operatively moving upwardly or downwardly. The supporting
base 53 is provided with a supporting arm 54 that is driven so as to extend or contract
in a horizontal direction. The supporting arm 54 is provided with a pair of supporting
portions 54a at separate positions along the line of the conveyance of the carriage
D.
[0103] With the arrangement of the unloading apparatus in the unloading step P5, the carriage
D with the vehicle body W loaded thereon is conveyed from the baking step P4 to the
unloading step P5 and then stopped at the loading/unloading station S1. As the carriage
D suspended, the supporting arms 54, 54 are extended from the supporting bases 53,
53 disposed at lower positions of the guide posts 52, 52 and the supporting bases
53, 53 are operated to move upwardly to allow the supporting portions 54a, 54a to
support the side sills or floor frame portions of the vehicle body W, then lift up
the vehicle body W from the carriage D and raise it to a higher position. The carriage
D is conveyed to the rewinding step P6 and instead a carriage D to be used in the
assembly line is then conveyed to the loading/unloading station S1.
[0104] The supporting bases 53, 53 with the vehicle body W supported thereon are then lowered
to load the vehicle body W on the carriage D for the assembly line, and the supporting
arms 54, 54 are shortened to unload the vehicle body W.
[0105] The loading of a freshly overcoated vehicle body W on the carriage D in the loading
step P7 is effected in substantially the order opposite to the order of the unloading
step P5.
[0106] It is preferred that the carriage D is held tightly at the predetermined position
by using, for example, a positioning apparatus for clamping the carriage D from the
front and rear and the left-hand and right-hand directions while the vehicle body
W is loaded or unloaded. The loading/unloading apparatus may have hangers at an upper
position which are constructed so as to be conveyed intermittently. In this case,
the vehicle body W may be shifted from the lifter 51 to the hangers, and the hangers
then raise the vehicle body W and convey it above a carriage for the assembly line.
The vehicle body W is then shifted again from the hangers to another lifter that is
in turn conveyed to the carriage for the assembly line.
Rewinding Mechanism T:
[0107] A rewinding mechanism T is to store the restoring force within the spring 64 (64-1
and 64-2). In this embodiment, the rewinding mechanism T is disposed on a passage
of conveying carriages D in a nonexplosive zone immediately prior to the loading of
non-overcoated vehicle bodies W on the carriages D.
[0108] Referring to FIG. 26, the rewinding mechanism T is shown to include a pair of left
and right guide posts 121, 121 with a slider 122 disposed on each of the guide posts
121, 121 slidably in an upward or downward direction. The slider 122 is moved upwardly
or downwardly by a motor 123 through a wire 124. Between the left and right sliders
122, 122 is bridged a holding bar 125, and a casing 126 is fixed on the midway of
the holding bar 125. As shown in FIG. 27, an air motor 127 and a decelerator 128 are
disposed in the casing 126. An output shaft 128a of the decelerator 128 extends towards
outside the casing 126 and an engaging box 129 is fixed to the tip portion of the
output shaft 128a.
[0109] With this arrangement, as shown in FIG. 27, as a carriage D approaches from the unloading
step P5 to the rewinding step P6, the casing 126 is being lowered to the carriage
D. Then the carriage D is caused to approach until the engaging portion 33 for the
rewinding purpose disposed on the carriage D is caused to engage with the engaging
box 129. Thereafter the motor 127 is driven to rotate the engaging portion 33 in order
to rewind the spring 64 for producing the restoring force therewithin.
[0110] After the spring 64 was rewound on the force storing drum 63, the carriage D is once
returned back toward the unloading step P5 to disengage from the engaging box 129
and then the casing 126 is raised in an upward direction to allow the carriage D to
convey through the left and right guide posts 121, 121 to the coming loading step
P7.
[0111] The rewinding mechanism T may be designed such that an actuator for the exclusive
use is disposed separately or that a displacement of the carriage D against the rails
23, 23 is utilized. In this case, for example, a rack bar is disposed in a fixed manner
along the locus of the conveyance of the carriage D by a predetermined length while
the carriage D is provided rotatively with a gear engageable with the rack bar, whereby
the spring 64 is caused to be rewound in association with the rotation of the gear
(for instance, a connection between a gear and the force storing drum 62 utilizing
a wire and the drum on which the wire is wound). It is a matter of course that the
rack bar is disposed by a length corresponding to the number of revolutions of the
gear necessary for storing the restoring force. The rack bar may be mounted at a few
positions along the locus of the conveyance of the carriage D, for example, immediately
prior to the steps P1, P2 and P3. With this arrangement, it is advantageous that lengths
of the springs 64 used in the embodiments as shown in FIGS. 9 and 10 may be shortened.
Variants in Rotation Driving Unit K2:
[0112] FIG,. 34 shows another example of variants in rotation driving units K2, in which
a spiral spring 64-3 is used as the spring and a speed governing mechanism Z.
[0113] One end of the spiral spring 64-3 is fixed to the box 27 and the other end thereof
is fixed to a rotation shaft 140. The rotation of the rotation shaft 140 is transmitted
through the sequence of a gear 141, a gear 142, a shaft 143, a gear 144, a gear 145,
a shaft 146, a cam clutch 150, a sprocket 147, a chain 148 and a sprocket 149 to the
output shaft 31.
[0114] The cam clutch 150 is designed so as to transmit only the rotation of the shaft 146
in the arrow direction in FIG. 34 to the sprocket 147, corresponding to the rotational
direction based on the restoring force of the spring 64-3. On the shaft 146 is mounted
a constant load mechanism M of the type similar to that shown in FIG. 12.
[0115] The speed governing mechanism Z is shown to contain a jaw gear 151, a feed jaw 152
and a pendulum 153. As shown specifically in FIGS. 35 and 36, the jaw gear 151 is
fixed to one end of the shaft 146. As shown more specifically in FIGS. 37 to 40, the
jaw gear 151 is provided with six jaw portions
a to
f, inclusive, at equal distances on the outer periphery. The feed jaw 152 is disposed
to engage with the jaw gear 151 and a pair of left and right jaw portions 152a and
152b thereof and connected pivotally about a shaft 154. The pendulum 153 is shown
to contain a supporting arm 153a with its upper end portion fixed pivotally about
the feed jaw 152 and a weight 153b mounted at the bottom end of the supporting arm
153a. The speed governing mechanism Z rotates the shaft 146 at constant speeds by
a pivoting cycle determined by the pendulum 153 and the application of the rotating
force from the springs 64-3 in a predetermined direction, for example, in the clockwise
direction in FIGS. 37 to 40. The order of operating the jaw gear 151 and the feed
jaw 152 is from FIG. 37 through FIGS. 38 and 39 to FIG. 40. After FIG. 40, the jaw
gear 151 and the feed jaw 152 proceed to FIG. 37, and the operation is continuously
repeated in the identical order. More specifically, as shown in FIG. 37, the jaw portion
a of the jaw gear 151 is engaged with the right jaw portion 152a of the feed jaw 152.
The feed jaw 152 is then operated to rotate the right jaw portion 152a pivotally about
the shaft 154 in the counterclockwise direction to disengage the jaw portion
a of the jaw gear 151 with the right jaw portion 152b. As the feed jaw 152 proceeds
to rotate, the right jaw portion 152a is disengaged from the jaw portion
a of the jaw gear 151 as shown in FIG. 38. Then the jaw gear 151 is allowed to rotate
in the clockwise direction. The clockwise rotation of the jaw gear 151 is caused to
suspend as the feed jaw 152 is kept on rotating about in the counterclockwise direction
and the left jaw portion 152a is allowed to engage the jaw portion
c of the feed jaw 151 as shown in FIG. 39. The feed jaw 152 is then pivoted in the
clockwise direction disengaging the jaw gear 151 from the left jaw portion 152a and
allowing the jaw gear 151 to rotate in the clockwise direction as shown in FIG. 40.
The feed jaw 152 is further pivoted in the clockwise direction to cause the right
jaw portion 152b to engage the jaw portion
b of the jaw gear 151 in a state as shown in FIG. 37. In summary, the jaw gear 151
is designed so as to proceed to rotate by one jaw portion only from one jaw portion
to another following thereafter.
[0116] FIG. 41 shows a further example of variants in rotation driving units K2, in which
the same elements as those in FIG. 34 are represented by the same reference numerals.
The rotation driving unit K2 is shown to use a torsion spring coil 64-4 wound on the
shaft 140 as the spring. One end of the torsion spring coil 64-4 is fixed to the box
27 and the other end thereof is fixed to the shaft 140. The rotation of the shaft
140 is designed so as to be transmitted from the sprocket 155 through another sprocket
157 to a gear 159. The sprocket 155 is connected to the sprocket 157 with a chain
156, and the sprocket 157 is in turn connected to the gear 159 with a shaft 158. The
gear 159 is further arranged to engage with the gear 142 and the rotation transmitted
to the gear 142 is kept on being transmitted to the rotation shaft 5 of the rotation
device 1 in the same manner as shwon in FIG. 34. By using the chain 156, the torsion
spring coil 64-4 of a long length may be disposed at a low position like under the
supporting base 21 of the carriage D.
Torque Switching Means:
[0117] A spring as a source for driving rotation may be of a type capable of being employed
for both the start-up and the continous rotation. The spring may be disposed at either
of the front and rear positions only, thereby applying a rotating force to the vehicle
body W from one of the front and rear sides only. In the case that there is employed
the spring of the type usable for both the start-up and the continuous rotation, the
restoring force produced by the spring may be designed so as to be transmitted to
the vehicle body W through a transmission by causing deceleration at the time of the
start-up and acceleration after the start-up by the transmission.
[0118] FIG. 42 shows an example of such torque switching transmission 136. A smaller-size
gear 131 and a larger-size gear 132 are fixed on the rotation shaft 62b rotatable
subject to the restoring force of the spring 64, and an integral set of a larger-size
gear 133 and a smaller-size gear 134 is fitted to the output shaft 31 in a spline
manner. By operatively moving a lever 135 in the arrow direction to the position in
FIG. 42 where the larger-size gear 133 is caused to engage the smaller-size gear 131,
on the one hand, the rotation of the rotation shaft 62b is allowed to be transmitted
to the output shaft 31 in a decelerating manner, thereby securing a large amount of
torque for the start-up. By operatively moving the lever 135 in the right-hand direction
in FIG. 42 to the position where the smaller-size gear 134 is caused to engage the
larger-size gear 132, on the other hand, the rotation of the rotation shaft 62b is
accelerated and transmitted to the output shaft 31, thereby securing a small amount
of torque for the continuos rotation. The displacement of the lever 135 may be conducted
by means of a mechanism as shown in FIG. 14.
[0119] As the torque switching mechanism as described above can render the torque transmitted
from the spring to the coating substrate such as the vehicle body W larger at the
build-up time of the rotation than subsequent to the build-up time, it can permit
a secure start-up of the rotation of the coating substrate and make an amount of displacement
of the spring required per revolution of the coating substrate smaller after the start-up
of the rotation, thus enabling the coating substrate to be rotated as much as possible
within a limited range of the amount of displacement of the spring.
Variants in Rotation Devices:
[0121] FIG. 43 shows a front rotation device 1F′ to be mounted on the front side of the
vehicle body W. The front rotation device 1F′ is shown to include a pair of left and
right mounting brackets 202F, 202F, a pair of left and right stays 203F, 203F welded
to each mounting bracket 202F a bar 204F connected integrally between the left and
right stays 203F, 203F, and a rotation shaft 205F welded to the bar 204F. The front
rotation device 1F′ may be fixed through the brackets 202F, 202F to a front reinforcing
member of the vehicle body W such as the front side frames 11, 11. The front side
frames 11, 11 are usually provided with brackets 11a, 11a for mounting a bumper (not
shown) so that the brackets 202F, 202F may be fixed detachably with bolts (not shown)
to the brackets 11a, 11a on the side of the vehicle body W.
[0122] A rear rotation device 1R′ to be mounted on the rear side of the vehicle body W is
shown in FIG. 44 and is constructed in substantially the same manner as with the front
rotation device 1F′. The same elements as those in the front rotation device 1F′ will
be represented by the same reference symbols and numerals and the reference symbol
"R" after the reference numerals is used in the following description instead of "F"
as long as the context is interpreted so as to cause no contradiction. The rear rotation
device 1R′ is fixed detachably through the brackets 202R, 202R of the rear rotation
device 1R′ to the rear side frames 12, 12 at the rear portion of the vehicle body
W as a rear reinforcing member. As the rear side frames 12, 12 are usually welded
in advance with brackets for mounting bumpers, the rear rotation device 1R′ may be
mounted through the brackets fro mounting the bumpers.
[0123] The front and rear rotation devices 1F′ and 1R′ are disposed in a state of being
mounted to the vehicle body W to cause the front and rear rotation shafts 205F and
205R to be located in a straight line so as to allow this line to coincide with the
axis of rotation
l.
[0124] The front and rear rotation device 1F′ and 1R′ may be prepared for exclusive uses
according to kinds of vehicle bodies.
Variants in Carriages:
[0125] FIGS. 45 to 47 show another example of variants in carriages. The carriage D′ is
constructed so as to rotate the vehicle body W utilizing a displacement of the carriage
D′ against the rails 23, 23. The rotation devices 1F′ and 1R′ as shown in FIGS. 43
and 44 may be used for the carriage D′. The same elements are represented by the same
reference numerals as shown in FIG. 5. On the base 21 is mounted one front support
224, two intermediate supports 225, 226, and one rear support 227, each standing upright.
Between the intermediate support 226 and the rear support 227 is a supporting space
30 extending long in the front and rear directions, where the vehicle body W is supported
when loaded.
[0126] The vehicle body W is loaded on the carriage D′ and supported in the supporting space
30 rotatively to the intermediate support 226 and the rear support 227. The vehicle
body W is disposed to be rotated at the front portion thereof against the intermediate
support 226 by means of the front rotation device 1F′ and at the rear portion thereof
against the rear support 227 by means of the rear rotation device 1R′.
[0127] The front rotation shaft 205F of the front rotation device 1F′ is disposed to be
rotatively connected to or disconnected from the intermediate support 226 in a downward
or upward direction. The rear rotation shaft 205R of the rear rotation device 1R′
is likewise disposed to be rotatively connected to or disconnected from the rear support
227 in a downward or upward direction, and the rear rotation device 1R′ is engaged
tightly in the direction of the rotational axis
l. The intermediate support 226 is provided with a cut-away portion 226a opening toward
the upper end surface (FIGS. 28, 29 and 30), and the rear support 227 is also provided
with a cut-away portion 227a opening toward the upper end surface (FIGS. 28, 32 and
33). These cut-away portions 226a and 227a are formed in a size sufficiently large
to insert the rotation shafts 205F and 205R of the front and rear rotation devices
1F′ and 1R′ in a secured manner, respectively. The rear rotation shaft 205R of the
rotation device 1R′ is provided with a flange portion 205a, and the rear support 227
is provided with a second cut-away portion 227b in a shape corresponding to and engageable
with the flange portion 205a of the rear rotation shaft 205R communicating with the
first cut-away portion 227a. This construction permits the connection or disconnection
of the rear rotation device 1R′ to or from the first and second cut-away portions
227a and 227b of the rear support 227 in a downward or upward direction and causes
the rear rotation device 1R′ to be so held in the flange portion 205a of the rotation
shaft 205R tightly and securedly by the stopper action of the flange portion 205a
so as to move in neither forward nor backward direction.
[0128] The vehicle body W is designed so as to be rotated by the front rotation shaft 205F
of the front rotation device 1F′ so that the front rotation shaft 205F is provided
at its end portion with a connection portion 205b as will be described below (see
also FIG. 43).
[0129] A converting mechanism 231 is disposed to convert a displacement of the carriage
D′ against the rails 23, 33 into a rotation. The converting mechanism 231 contains
a rotation shaft 232 extending from the base 21 in an upward and downward direction
and being supported rotatively on the base 21, a sprocket 233 fixed on the lower end
portion of the rotation shaft 232, and a chain 234 engaged with the sprocket 233.
The chain 234 is disposed parallel to the retraction wire 25 and in such a state that
it does not move along the rails 23, 23. Thus, as the carriage D′ is conveyed by retracting
the retraction wire 25, the sprocket 233 is caused to be rotated while engaged with
the chain 234 disposed in an unmovable manner, thus leading to the rotation of the
rotation shaft 232.
[0130] A transmitting mechanism 235 is disposed to transmit the rotation of the rotation
shaft 232 to the front rotation shaft 205F of the front rotation device 1F′. The transmitting
mechanism 235 contains a casing 236 fixed on the rear surface of the front support
224, a rotation shaft 237 extending from the casing 236 in the transverse (front and
rear) direction and supported rotatively thereby, a pair of bevel gears 238 and 239
for rotating the rotation shaft 237 in association with the rotation shaft 232, and
a connection shaft 240 connected to the front support 225 rotatively and slidably
in the front and rear directions. The connection shaft 240 is connected to the rotation
shaft 237 in a spline manner at a position represented by 241 in FIG. 45. This construction
permits a rotation of the connection shaft 240 in association with the rotation of
the rotation shaft 232. The rotation shaft 237 and the connection shaft 240 are disposed
to allow their axes to be located in the line coinciding with the rotational axis
l.
[0131] As shown in FIGS. 28 to 30, the connection shaft 240 is connected to or disconnected
from the front rotation shaft 205F of the front rotation device 1F′. A connecting
portion 205b in a cross shape is formed on the top end portion of the front rotation
shaft 205F of the front rotation device 1F′, and a box portion 240a having an engaging
hollow 240c engageable tightly with the connecting portion 205b is provided at the
rear portion of the connection shaft 240. By moving the connection shaft 240 in a
sliding manner through a rod 243, for example, using a hydraulic cylinder 242, the
connecting portion 205b is connected to or disconnected from the engaging hollow 240c
of the box portion 240a. The connection shaft 240 is rotated integrally with the rotation
shaft 205 when they engage each other. The rod 243 is disposed inside a ring groove
240b formed on the outer periphery of the box portion 240a in a manner to interfere
with the rotation of the connection shaft 240.
[0132] This arrangement enables the rotation shafts 205F and 205R of the respective front
and rear rotation device 1F′ and 1R′ to be supported to the intermediate support 226
and the rear support 227 rotatively in such a state as being unmovable in the front
and rear directions by lowering the vehicle body W down to the carriage D′ in a state
that the connection shaft 240 is displaced to the right in FIG. 45. Thereafter the
connecting portion 205b of the rotation shaft 205F is engaged with the engaging hollow
240c of the connection shaft 240, whereby the vehicle body W is allowed to rotate
about a predetermined rotational axis
l by retracting the carriage D′ by the retraction wire 25. The vehicle body W may be
unloaded from the carriage D′ by the order of the procedures opposite to the order
of the procedures for loading.
[0133] It is to be noted further that, if the chain 234 would be arranged so as to be driven
by a motor or so on to be mounted separately, the vehicle body W can be rotated even
in a state that the carriage D′ is suspended.
Variants in Paints (Powder Coating):
[0134] In the spraying step P2, a powder coating may be used for spraying on the vehicle
body W.
[0135] FIG. 48 shows influences of film thicknesses of powder coatings on limits on sags,
in which two cases of film thicknesses of 100 µm and 120 µm are given. It is to be
understood from the results of FIG. 48 that in each case a heat flow is caused in
5 to 10 minutes after the start of baking. In conventional coating procedures for
spraying a powder coating, a maximum film thickness in the spraying step P2 is restricted
to as thick as 80 µm or less on account of sags caused by the heat flow.
[0136] On the other hand, the method according to the present invention permits a powder
coating to be sprayed on the vehicle body W in the spraying step P2 in a film thickness
thicker than 80 µm - even 100 µm, for example. In the baking step P4 according to
the present invention during which the heat flow is caused, the vehicle body W is
caused to rotate. It is to be noted here that the rotation of the vehicle body W may
be conducted at least during a period of time when the heat flow occurs. It is not
necessary to rotate the vehicle body W during a whole period of time of the baking
step P4.
[0137] It is further noted that, in instances where a powder coating is used, the setting
step P3 for evaporating a solvent in the range of low temperatures can be omitted
because the powder coating contains no such solvent.
[0138] The tests shown in FIG. 48 were conducted under the following conditions:
(a) Paint: acrylic powder coating ("Powdax A": Nippon Paint K.K.)
(b) Coater: electrostatic powder coating device (Model: GX101; Onoda Cement K.K.)
(c) Applied voltage: -60 KV
(d) Rate of Coating: 180 grams /minute
(e) Pressure of air conveying paint: 2.0 kg/cm²
(f) Distance of spraying: 25 cm
Variants in Paints (Two-Part Thermosetting Paint):
[0139] In the spraying step P2 according to the step of the present invention, a two-part
thermosetting paint may be used as a coating paint, in which it contains a resin as
a main component and a curing agent.
[0140] FIG. 49 shows influences of film thicknesses of a two-part thermosetting paint on
limits of sags, in which three cases of 55 µm, 65 µm and 75 µm are given. It is to
be noted that in each case a peak of sags is caused to occur in the middle stage of
the setting step P3 and no sags are caused to occur in the baking step P4.
[0141] In conventional coating procedures, on the one hand, a maximum film thickness of
a two-part thermosetting paint sprayed in the spraying step P2 cannot exceed 40 µm
on account of sags caused to occur in the setting step P3. In accordance with the
present invention, on the other hand, a maximum film thickness of a two-part thermosetting
paint sprayed on the vehicle body W in the spraying step P2 can be as thick as 65
µm, for example, because the vehicle body W is caused to rotate in the setting step
P3 where sags occur. It is further noted herein that it is not necessary to cause
the vehicle body W to rotate in the baking step P4.
[0142] The test conditions used in FIG. 49 are as follows:
(a) Paint: polyester urethane paint white ("R-263"; Nippon Bee Chemical K.K.)
Main resin: polyester polyol white
Curing agent: hexamethylene diisocyate
Mixing ratio (weight): 4 (main resin) to 1 (curing agent)
(b) Coater: compression-type air spray gun (Model "WIDER-W71"; Iwata Tosoki K.K.)
(c) Spraying viscosity: 16 seconds/ Ford Cup #4)
(d) Spraying rate: 350 cc/minute
(e) Atomizing air pressure: 4.0 kg/cm²
(f) Spraying distance: 30 cm
(g) Number of coatings: two (intervals: 3 minutes)
Further Variants:
[0143] The present invention may be performed by further variants as follows:
(a) Springs:
[0144] As the spring as a source of driving the rotation may be employed a gas spring comprising
a cylinder in which gases are enclosed under a predetermined pressure and piston rod
inserted in the cylinder. A restoring force produced by the gas spring is embodied
as a straight movement of the piston rod so that the straight movement may be converted
into a rotational movement, for example, by a rack or a pinion.
[0145] The spring for the start-up of the rotation may also be a one-way clutch instead
of the clutch 85 of the friction type as shown in FIG. 15.
(b) Coating substrates:
[0146] The coating substrates to which the present invention can be applicable may further
include, for example, casings for electric utensils and steel household furnishings.
(c) Switching of rotation:
[0147] The switching from the rotation of the vehicle body W to the suspension thereof or
vice versa and a shift in the rotational direction of the vehicle body W may be conducted
using an actuator for exclusive use such as an air motor, regardless of whether the
carriage D′ is being conveyed or suspended.
[0148] Referring to FIG. 45, the sprocket 233 may be provided with a pair of first chains
engaging with another pair of second chains (each corresponding to the chain 234)
from the opposite side in the diametric direction. Each of the chains are operatively
driven. In this case, a rack bar or a pinion may be used instead of the chain 234
or the sprocket 233.
[0149] When the first chains are suspended and the second chains are in a free state, the
vehicle body W is caused to rotate in one direction in association with the conveyance
of the carriage D′.
[0150] When the first chains are in a free state and the second ones are suspended, the
vehicle body W is caused to rotate in the direction opposite to the direction rotated
in the above instance, as the carriage D′ is being conveyed.
[0151] When the first and second chains are all in a free state, the vehicle body W is not
caused to rotate.
[0152] When the first chains are driven in one direction and the second ones are in a free
state, the vehicle body W is caused to rotate in one direction even if the carriage
D′ is suspended.
[0153] When the first chains are driven in other directions and the second one are in a
free state or vice versa, the vehicle body W is caused to rotate in the direction
opposite to that rotated in the immediately above instance even if the carriage D′
is suspended.
[0154] Referring again to FIG. 45, a rack bar or a pinion may be employed instead of the
chain 234 or the sprocket 233. In instances where the rack bar is disposed in a fixed
state (given the conveyance of the carriage D′ for the rotation of the vehicle body
W in this case), the rack bar may be disposed at intervals or on the left-hand and
right-hand sides at predetermined positions. This arrangement permits a rotation of
the vehicle body W in a predetermined direction and a suspension of the vehicle body
W at a predetermined position as the carriage D′ is conveyed to a predetermined position.
1. A method for coating a vehicle with a paint, the method including a spraying step
in which the paint is sprayed onto the vehicle body to thereon form a film of paint
and further including a baking step in which the vehicle body is held in an elevated
ambient temperature while being rotated, with all the paint thereon, about a horizontal
axis until the paint is baked,
characterized in that the paint sprayed onto the vehicle body is one which will become
flowable at the temperature applied in the baking step, in that, in the spraying step,
the paint is sprayed onto the vehicle body in a film thickness exceeding a threshold
film thickness at which sagging of the paint will occur at least on a vertically extending
surface of the vehicle body, and in that the vehicle body is rotated about said horizontal
axis in the baking step at a speed high enough to substantially prevent sagging of
the paint film on the vehicle body due to gravity and low enough to prevent sagging
of the paint film as a result of centrifugal force.
2. The coating method according to claim 1, wherein the vehicle body is rotated in clockwise
direction and in counterclockwise direction.
3. The coating method according to claim 2, wherein the vehicle body is rotated continuously
in clockwise direction and thereafter in counterclockwise direction.
4. The coating method according to claim 2, wherein the vehicle body is rotated alternately
in clockwise direction and counterclockwise direction.
5. The coating method according to claim 2, wherein the vehicle body is rotated in both
directions each through an angle of at least 90°.
6. The coating method according to any of claims 1 to 5, wherein the vehicle body to
be coated has an intermediate coating.
7. The coating method according to claim 1, wherein the vehicle body is rotated in one
direction only.
8. The coating method according to claim 7, wherein the vehicle body is continuously
rotated.
9. The coating method according to claim 7, wherein the vehicle body is intermittently
rotated.
10. The coating method according to one of claims 1 to 9, wherein the paint sprayed upon
the vehicle body is a powder paint.
11. The coating method according to claim 10, wherein the powder paint is sprayed to form
a film thickness beyond its threshold film thickness of about 80 µm.
12. The coating method according to claim 10 or 11, wherein the sagging allowed is less
than 2 mm.
13. The coating method according to any of claims 10 to 12, wherein the vehicle body is
rotated at least at an initial stage of the baking step.
14. The coating method according to any of claims 1 to 13, wherein the vehicle body is
held substantially stationary during the spraying step.
15. The coating method according to any of claims 1 to 14, wherein the vehicle body is
rotated in a preparatory step prior to the spraying step to thereby remove foreign
matters from the vehicle body.
16. The coating method according to claim 15, wherein the vehicle body is conveyed by
a rotary carriage from the preparatory step to the baking step.
17. The coating method according to claim 16, wherein the vehicle body is conveyed on
the same carriage from the preparatory step to the baking step.
18. The coating method according to any of claims 1 to 17, wherein the horizontal axis
of rotation passes through the center of gravity of the vehicle body.
19. The coating method according to claim 1, wherein the horizontal axis of rotation extends
in the longitudinal direction of the vehicle body.
20. The coating method according to any of claims 1 to 19, wherein the vehicle body is
rotated at a speed of 380cm/sec or slower, measured at a radially outward tip portion
of the vehicle body.
21. The coating method according to claim 1, wherein the baking step is the only drying
step for drying of the paint.
22. The coating method according to claim 1, wherein the paint sprayed upon the vehicle
body is a thermosetting paint.
23. The coating method according to claim 22, wherein drying of the paint on the vehicle
body comprises a setting step and a subsequent baking step, whereby the vehicle body
is held in an ambient temperature during the setting step which is lower than the
ambient temperature during the baking step and whereby the vehicle body is rotated
about said horizontal axis also in the setting step.
24. The coating method according to claim 22 or claim 23 wherein the thermosetting paint
is coated in a film thickness beyond its threshold film thickness of 40 µm.
25. The coating method according to any of claims 22 to 24 wherein the sagging allowed
is 2 mm or less.
26. The coating method according to claim 25, wherein the vehicle body is rotated at a
speed which causes sagging at a maximum sagging speed at which the paint sags due
to the heat flow created during the baking step.
27. A coating apparatus in a coating line for coating a vehicle body with a paint, comprising
a spraying means for spraying the paint onto the vehicle body to thereon form a film
of paint, a body conveying means (D, D') for holding the vehicle body and conveying
same along the coating line, a rotation device (1) associated with said body conveying
means for rotating the vehicle body about a substantially horizontal axis in a drying
station (P3, P4), including a baking station (P4), for curing the paint,
characterized in that the spraying means is suitable for spraying of a paint of the
type which will become flowable at the temperature applied in the baking station,
in that the spraying means can be operated so as to spray the paint in a film thickness
exceeding a threshold film thickness at which sagging of the paint will occur at least
on a vertically extending surface of the vehicle body, and in that the rotation device
(1) within the baking station is provided for rotating the vehicle body at a speed
high enough to substantially prevent the sagging of the paint film on the vehicle
body due to gravity and low enough to prevent sagging of the paint film as the result
of centrifugal force.
28. The coating apparatus according to claim 27, wherein the vehicle body is held in such
a way that the horizontal rotational axis (ℓ) extends in the longitudinal direction
of the vehicle body.
29. The coating apparatus according to claim 27 or 28 wherein the rotation device (1)
rotates the vehicle body at a speed of 380cm/sec or slower.
30. The coating apparatus according to any of claims 27 to 29, wherein the body conveying
means (D) comprises a supporting means (26 to 29) for rotatably supporting the vehicle
body about its horizontal axis, a rotation driving means (K1, K2) comprising a spring
means (63, 64; 64-3) as a rotational driving source, and a transmitting mechanism
(L; 85 to 87; 140 to 149) for transmitting a restoring force of said spring means
as a rotating force to said supporting means.
31. The coating apparatus according to claim 30, wherein the coating line is provided
with a force storing means (62) for accumulating the restoring force of said spring
means.
32. The coating apparatus according to claim 30 or 31, wherein the body conveying means
(D) further comprises a speed governing mechanism (Z) for governing the rotational
speed of the vehicle body when driven by said rotation driving means within said speed
range.
33. The coating apparatus according to any of claims 30 to 32, wherein a torque switching
means (136) is provided for switching the driving torque of the spring means from
a higher value at start-up of the rotation of the vehicle body to a lower value subsequent
to start-up of the rotation.
34. The coating apparatus according to any of claims 30 to 32, wherein the spring means
comprises a first spring (64) for start-up of the rotation and a second spring (64)
for continuation of the rotation.
35. The coating apparatus according to any of claims 27 to 34, wherein a balancer mechanism
(41 to 44) is provided for shifting to substantial coincidence of the horizontal axis
of rotation and the center of gravity of the vehicle body supported by the body conveying
means.
36. The coating apparatus according to any of claims 27 to 35, wherein the body conveying
means further comprises a stopper mechanism (R) mounted on the body conveying means
for suspending the rotation of the vehicle body at a predetermined rotary position
when rotated in a setting station (P3) of the drying station (P3, P4).
37. The coating apparatus according to claim 27, wherein the body conveying means (D′)
is provided with a supporting means (26 to 29) for supporting the vehicle body rotatably
about said horizontal axis, with a toothed rotary member (233) connected to the vehicle
body supported by the supporting means, and wherein an elongated member (234) is provided
in mesh with the toothed rotary member and movable along a conveying passage (23)
on which the conveying means is conveyed.
38. The coating apparatus according to claim 37, wherein the toothed rotary member is
a sprocket or a gear and the elongated member is a chain or a rack.
39. The coating apparatus according to claim 27, wherein the body conveying means (D′)
comprises a supporting means (224 to 227) for rotatably supporting the vehicle body
about said horizontal axis, and a converting mechanism (231) connected to the vehicle
body when supported by the supporting means for converting a displacement of the body
conveying means into a rotational movement of the vehicle body.
40. The coating apparatus according to claim 39, wherein the converting mechanism comprises
a toothed rotary member (233) supported rotatably by the body conveying means and
connectable to the vehicle body supported by the supporting means, and an elongated
member (234) disposed along a conveying passage (23) of the body conveying means in
a fixed manner and meshing with the toothed rotary member (233).
41. The coating apparatus according to claim 39 wherein the conveying passage (23) of
the body conveying means (D′) is provided with a driving source (25) for displacing
of the body conveying means and with a drive means (234), disposed in parallel to
said driving source (25), for transmitting a driving force for rotation to said converting
mechanism (231).
42. The coating apparatus according to any of claims 27 to 41, wherein the spraying means
is suitable to apply a paint which causes thermal flow at the ambient temperature
in the baking station and sags only due to such thermal flow.
43. The coating apparatus according to claim 42, wherein the spraying means is one for
spraying of a powder paint.
44. The coating apparatus according to claim 43, wherein the spraying means is suitable
to apply the powder paint in a film thickness beyond the threshold film thickness
of about 80 µm.
45. The coating apparatus according to any of claims 42 to 44, wherein the body conveying
means is rotated at a speed equal to or faster than a maximum sagging speed of the
paint film in the baking station.
46. The coating apparatus according to any of claims 27 to 41, wherein the spraying means
is suitable to spray a paint which sags during a setting step in the drying station
as well as during the baking step in the baking station, and wherein the vehicle body
is rotated at substantially the same speed in the setting station as well as in the
baking station.
47. The coating apparatus according to claim 46, wherein the spraying means is suitable
to spray a thermosetting-type paint.
48. The coating apparatus according to claim 47, wherein the spraying means is suitable
to spray the thermosetting paint in a film thickness beyond the threshold film thickness
of about 40 µm.
49. The coating apparatus according to claim 46 or 47, wherein the vehicle body is rotated
at a speed equal to or faster than a speed whichever the maximum sagging speed of
the paint in the setting step or in the baking step is.
50. The coating apparatus according to any of claims 46 to 49, wherein the body conveying
means is conveyable between the setting station (P3) and the baking station (P4),
whereby a single body conveying means conveys a single vehicle body between these
stations.
1. Verfahren zum Lackieren eines Fahrzeuges, mit einer Spritzstufe, in welcher der Fahrzeugkörper
mit Lack gespritzt und darauf ein Lackfilm gebildet wird, und mit einer Einbrennstufe,
in welcher der Fahrzeugkörper mit dem darauf befindlichen Lack bei gleichzeitiger
Drehung um eine Horizontalachse auf einer erhöhten Umgebungstemperatur gehalten wird,
bis der Lack eingebrannt ist,
dadurch gekennzeichnet,
daß der auf den Fahrzeugkörper gespritzte Lack ein solcher ist, welcher bei der in
der Einbrennstufe eingestellten Temperatur fließfähig wird, daß in der Spritzstufe
der Fahrzeugkörper mit dem Lack mit einer Filmdicke gespritzt wird, welche eine Grenzfilmdicke
übersteigt, bei der zumindest auf einer vertikal ausgerichteten Oberfläche des Fahrzeugkörpers
ein Absacken des Lackes auftritt, und daß der Fahrzeugkörper um die genannte Horizontalachse
in der Einbrennstufe mit einer Geschwindigkeit gedreht wird, die ausreichend hoch
ist, um ein durch die Schwerkraft bedingtes Absacken des Lackfilms auf dem Fahrzeugkörper
weitgehend zu verhindern, und ausreichend niedrig ist, um ein Absacken des Lackfilms
aufgrund der Fliehkraft zu vermeiden.
2. Lackierverfahren nach Anspruch 1,
dadurch gekennzeichnet,
daß der Fahrzeugkörper im Uhrzeigersinn und im Gegenuhrzeigersinn gedreht wird.
3. Lackierverfahren nach Anspruch 2,
dadurch gekennzeichnet,
daß der Fahrzeugkörper kontinuierlich im Uhrzeigersinn und anschließend im Gegenuhrzeigersinn
gedreht wird.
4. Lackierverfahren nach Anspruch 2,
dadurch gekennzeichnet,
daß der Fahrzeugkörper abwechselnd im Uhrzeigersinn und im Gegenuhrzeigersinn gedreht
wird.
5. Lackierverfahren nach Anspruch 2,
dadurch gekennzeichnet,
daß der Fahrzeugkörper in beiden Richtungen um einen Winkel von zumindest 90° gedreht
wird.
6. Lackierverfahren nach einem der Ansprüche 1 bis 5,
dadurch gekennzeichnet,
daß der zu lackierende Fahrzeugkörper eine Zwischenlackschicht aufweist.
7. Lackierverfahren nach Anspruch 1,
dadurch gekennzeichnet,
daß der Fahrzeugkörper nur in einer Richtung gedreht wird.
8. Lackierverfahren nach Anspruch 7,
dadurch gekennzeichnet,
daß der Fahrzeugkörper kontinuierlich gedreht wird.
9. Lackierverfahren nach Anspruch 7,
dadurch gekennzeichnet,
daß der Fahrzeugkörper intermittierend gedreht wird.
10. Lackierverfahren nach einem der Ansprüche 1 bis 9,
dadurch gekennzeichnet,
daß der auf den Fahrzeugkörper aufgespritzte Lack ein Pulverlack ist.
11. Lackierverfahren nach Anspruch 10,
dadurch gekennzeichnet,
daß der Pulverlack derart aufgespritzt wird, daß sich eine Filmdicke über seiner Grenzfilmdicke
von etwa 80 µ einstellt.
12. Lackierverfahren nach Anspruch 10 oder 11,
dadurch gekennzeichnet,
daß ein Absacken von weniger als 2 mm zugelassen wird.
13. Lackierverfahren nach einem der Ansprüche 10 bis 12,
dadurch gekennzeichnet,
daß der Fahrzeugkörper zumindest in einer Anfangsphase der Einbrennstufe gedreht wird.
14. Lackierverfahren nach einem der Ansprüche 1 bis 13,
dadurch gekennzeichnet,
daß der Fahrzeugkörper während der Spritzstufe weitgehend stationär gehalten wird.
15. Lackierverfahren nach einem der Ansprüche 1 bis 14,
dadurch gekennzeichnet,
daß der Fahrzeugkörper in einer Vorbereitungsstufe vor der Spritzstufe gedreht wird,
um dadurch Fremdstoffe vom Fahrzeugkörper zu entfernen.
16. Lackierverfahren nach Anspruch 15,
dadurch gekennzeichnet,
daß der Fahrzeugkörper durch einen Drehwagen von der Vorbereitungsstufe in die Einbrennstufe
befördert wird.
17. Lackierverfahren nach Anspruch 16,
dadurch gekennzeichnet,
daß der Fahrzeugkörper auf ein und demselben Wagen von der Vorbereitungsstufe zur
Einbrennstufe befördert wird.
18. Lackierverfahren nach einem der Ansprüche 1 bis 17,
dadurch gekennzeichnet,
daß die horizontale Drehachse durch den Schwerpunkt des Fahrzeugkörpers verläuft.
19. Lackierverfahren nach Anspruch 1,
dadurch gekennzeichnet,
daß die horizontale Drehachse sich in Längsrichtung des Fahrzeugkörpers erstreckt.
20. Lackierverfahren nach einem der Ansprüche 1 bis 19,
dadurch gekennzeichnet,
daß der Fahrzeugkörper mit einer Geschwindigkeit von 380 cm/sec oder langsamer, gemessen
an einem radial außen liegenden Spitzenabschnitt des Fahrzeugkörpers, gedreht wird.
21. Lackierverfahren nach Anspruch 1,
dadurch gekennzeichnet,
daß die Einbrennstufe die einzige Trocknungsstufe für die Lacktrocknung ist.
22. Lackierverfahren nach Anspruch 1,
dadurch gekennzeichnet,
daß der auf den Fahrzeugkörper gespritzte Lack ein wärmeaushärtender Lack ist.
23. Lackierverfahren nach Anspruch 22,
dadurch gekennzeichnet,
daß die Trocknung des Lacks auf dem Fahrzeugkörper einen Setzvorgang und einen nachfolgenden
Einbrennvorgang umfasst, wobei der Fahrzeugkörper während des Setzvorganges in einer
Umgebungstemperatur gehalten wird, die niedriger als die Umgebungstemperatur während
des Einbrennvorganges ist, und wobei der Fahrzeugkörper um die genannte Horizontalchse
auch in dem Setzvorgang gedreht wird.
24. Lackierverfahren nach Anspruch 22 oder 23,
dadurch gekennzeichnet,
daß der wärmeaushärtende Lack mit einer Filmdicke über seiner Grenzfilmdicke von 40
µ aufgebracht wird.
25. Lackierverfahren nach einem der Ansprüche 22 bis 24,
dadurch gekennzeichnet,
daß ein Absacken von 2 mm oder weniger zugelassen wird.
26. Lackierverfahren nach Anspruch 25,
dadurch gekennzeichnet,
daß der Fahrzeugkörper mit einer Geschwindigkeit gedreht wird, die ein Absacken mit
einer maximalen Absackgeschwindigkeit verursacht, bei dem der Lack aufgrund einer
während der Einbrennstufe erzeugten Wärmeverflüssigung absackt.
27. Lackiereinrichtung in einer Lackierstrecke zum Lackieren eines Fahrzeugkörpers, mit
einer Spritzeinrichtung für das Aufspritzen des Lackes auf den Fahrzeugkörper zur
Ausbildung eines Lackfilms darauf, mit einer Fördereinrichtung (D, D') zur Halterung
des Fahrzeugkörpers und zu dessen Förderung längs der Lackierstrecke, mit einer der
Fördereinrichtung zugeordneten Drehvorrichtung (1) zum Drehen des Fahrzeugkörpers
um eine im wesentlichen horizontale Achse in einer Trocknungsstation (P3, P4), die
eine Einbrennstation (P4) zum Aushärten des Lacks umfasst,
dadurch gekennzeichnet,
daß die Spritzeinrichtung für das Spritzen einer Lackart geeignet ist, die bei der
in der Einbrennstation eingestellten Temperatur fließfähig wird, daß die Spritzeinrichtung
derart betreibbar ist, daß der Lack mit einer Filmdicke aufgespritzt wird, die eine
Grenzfilmdicke übersteigt, bei der ein Absacken des Lackes zumindest an einer vertikal
ausgerichteten Oberfläche des Fahrzeugkörpers auftritt, und daß die Drehvorrichtung
(1) in der Einbrennstation zur Drehung des Fahrzeugkörpers mit einer Geschwindigkeit
ausgelegt ist, die ausreichend hoch ist, um ein durch die Schwerkraft bedingtes Absacken
des Lackfilms auf dem Fahrzeugkörper weitgehend zu verhindern, und ausreichend niedrig
ist, um ein Absacken des Lackfilms aufgrund der Fliehkraft zu vermeiden.
28. Lackiereinrichtung nach Anspruch 27,
dadurch gekennzeichnet,
daß der Fahrzeugkörper darin derart gehalten ist, daß die horizontale Drehachse (ℓ)
sich in Längsrichtung des Fahrzeugkörpers erstreckt.
29. Lackiereinrichtung nach Anspruch 27 oder 28,
dadurch gekennzeichnet,
daß die Drehvorrichtung (1) den Fahrzeugkörper mit einer Geschwindigkeit von 380 cm/sec
oder langsamer dreht.
30. Lackiereinrichtung nach einem der Ansprüche 27 bis 29,
dadurch gekennzeichnet,
daß die Fördereinrichtung (D) eine Tragvorrichtung (26 bis 29) zur drehbaren Abstützung
des Fahrzeugkörpers um dessen Horizontalachse, einen Drehantrieb (K1, K2) mit einer
Federeinrichtung (63, 64; 63-3) als Kraftquelle für den Drehantrieb und einen Übertragungsmechanismus
(L; 85 bis 87; 140 bis 149) zur Übertragung einer Rückstellkraft der Federeinrichtung
als Drehkraft auf die Tragvorrichtung aufweist.
31. Lackiereinrichtung nach Anspruch 30,
dadurch gekennzeichnet,
daß die Lackierstrecke mit einer Kraftspeichereinrichtung (62) zum Speichern der Rückstellkraft
der Federeinrichtung ausgestattet ist.
32. Lackiereinrichtung nach Anspruch 30 oder 31,
dadurch gekennzeichnet,
daß die Fördereinrichtung (D) einen Steuermechanismus (Z) zur Steuerung der Drehgeschwindigkeit
des Fahrzeugkörpers bei dessen Drehung durch den Drehantrieb in dem genannten Geschwindigkeitsbereich
aufweist.
33. Lackiereinrichtung nach einem der Ansprüche 30 bis 32,
dadurch gekennzeichnet,
daß eine Drehmoment-Schalteinrichtung (136) vorgesehen ist, um das Antriebsmoment
der Federeinrichtung von einem höheren Wert zu Beginn der Drehung des Fahrzeugkörpers
auf einen niedrigeren Wert anschließend an den Drehbeginn umzuschalten.
34. Lackiereinrichtung nach einem der Ansprüche 30 bis 32,
dadurch gekennzeichnet,
daß die Federeinrichtung eine erste Feder (64) für den Drehbeginn und eine zweite
Feder (64) für die fortgesetzte Drehung aufweist.
35. Lackiereinrichtung nach einem der Ansprüche 27 bis 34,
dadurch gekennzeichnet,
daß eine Unwucht-Ausgleichseinrichtung (41 bis 44) vorgesehen ist, um die horizontale
Drehachse und den Schwerpunkt des auf der Tragvorrichtung abgestützten Fahrzeugkörpers
bis zur Übereinstimmung zu verschieben.
36. Lackiereinrichtung nach einem der Ansprüche 27 bis 35,
dadurch gekennzeichnet,
daß die Fördereinrichtung eine darauf montierte Stop-Vorrichtung (R) aufweist, um
die Drehung des Fahrzeugkörpers in einer vorbestimmten Drehstellung aufzuheben, wenn
der Fahrzeugkörper in einer Setzstation (P3) der Trocknungsstation (P3, P4) gedreht
wird.
37. Lackiereinrichtung nach Anspruch 27,
dadurch gekennzeichnet,
daß die Fördereinrichtung (D') mit einer Tragvorrichtung (26 bis 29) zur drehbaren
Abstützung des Fahrzeugkörpers um die genannte Horizontalachse und mit einem verzahnten
Drehelement (233), das mit dem auf der Tragvorrichtung angeordneten Fahrzeugkörper
verbunden ist, ausgestattet ist, und daß ein langgestrecktes Element (234) mit dem
verzahnten Drehelement in Eingriff steht und längs einem Förderweg (23), auf dem die
Fördereinrichtung verfahrbar ist, bewegbar ist.
38. Lackiereinrichtung nach Anspruch 37,
dadurch gekennzeichnet,
daß das verzahnte Drehelement ein Kettenzahnrad oder ein Stirnrad und das langgestreckte
Element eine Kette bzw. eine Zahnstange ist.
39. Lackiereinrichtung nach Anspruch 27,
dadurch gekennzeichnet,
daß die Fördereinrichtung (D') eine Tragvorrichtung (224 bis 227) zur drehbaren Abstützung
des Fahrzeugkörpers um die genannte Horizontalachse sowie einen mit dem Fahrzeugkörper
in dessen auf der Tragvorrichtung abgestützten Zustand verbundenen Wandlermechanismus
(231) aufweist, um eine Verschiebung der Fördereinrichtung in eine Drehbewegung des
Fahrzeugkörpers umzusetzen.
40. Lackiereinrichtung nach Anspruch 39,
dadurch gekennzeichnet,
daß der Wandlermechanismus ein drehbar an der Fördereinrichtung gelagertes verzahntes
Drehelement (233), das mit dem auf der Tragvorrichtung angeordneten Fahrzeugkörper
verbunden werden kann, sowie ein längs des Förderweges (23) der Fördereinrichtung
fest angeordnetes langgestrecktes Element (234) aufweist, welches mit dem verzahnten
Drehelement (233) in Eingriff steht.
41. Lackiereinrichtung nach Anspruch 39,
dadurch gekennzeichnet,
daß der Förderweg (23) der Fördereinrichtung (D') mit einem Antrieb (25) zum Verfahren
der Fördereinrichtung und mit Antriebsmitteln (234), die sich parallel zu dem Antrieb
(25) erstrecken, ausgestattet ist, um eine Dreh-Antriebskraft auf den genannten Wandlermechanismus
(231) zu übertragen.
42. Lackiereinrichtung nach einem der Ansprüche 27 bis 41,
dadurch gekennzeichnet,
daß die Spritzeinrichtung zum Aufbringen eines Lackes geeignet ist, der bei der Temperatur
in der Einbrennstation thermisch zum Fließen kommt und allein aufgrund dieser thermisch
bedingten Fließfähigkeit absackt.
43. Lackiereinrichtung nach Anspruch 42,
dadurch gekennzeichnet,
daß die Spritzeinrichtung eine solche zum Spritzen eines Pulverlacks ist.
44. Lackiereinrichtung nach Anspruch 43,
dadurch gekennzeichnet,
daß die Spritzeinrichtung zum Auftragen des Pulverlacks mit einer Filmdicke über der
Grenzfilmdicke von etwa 80 µ geeignet ist.
45. Lackiereinrichtung nach einem der Ansprüche 42 bis 44,
dadurch gekennzeichnet,
daß die Fördereinrichtung mit einer Geschwindigkeit gedreht wird, die gleich oder
grösser als die maximale Absackgeschwindigkeit des Lackfilms in der Einbrennstation
ist.
46. Lackiereinrichtung nach einem der Ansprüche 27 bis 41,
dadurch gekennzeichnet,
daß die Spritzeinrichtung zum Spritzen eines Lackes geeignet ist, der während eines
Setzvorganges in der Trocknungsstation sowie während des Einbrennvorganges in der
Einbrennstation absackt, und daß der Fahrzeugkörper mit im wesentlichen der gleichen
Geschwindigkeit in der Setzstation und in der Einbrennstation gedreht wird.
47. Lackiereinrichtung nach Anspruch 46,
dadurch gekennzeichnet,
daß die Spritzeinrichtung zum Spritzen eines Lackes der wärmeaushärtenden Art geeignet
ist.
48. Lackiereinrichtung nach Anspruch 47,
dadurch gekennzeichnet,
daß die Spritzeinrichtung zum Spritzen des wärmeaushärtenden Lackes mit einer Filmdicke
über der Grenzfilmdicke von etwa 40 µ geeignet ist.
49. Lackiereinrichtung nach Anspruch 46 oder 47,
dadurch gekennzeichnet,
daß der Fahrzeugkörper mit einer Geschwindigkeit gedreht wird, die gleich oder grösser
als eine Geschwindigkeit ist, welche die maximale Absackgeschwindigkeit des Lackes
in dem Setzvorgang oder in dem Einbrennvorgang ist.
50. Lackiereinrichtung nach einem der Ansprüche 46 bis 49,
dadurch gekennzeichnet,
daß die Fördereinrichtung zwischen der Setzstation (P3) und der Einbrennstation (P4)
verfahrbar ist, wobei eine einzige Fördereinrichtung jeweils einen einzigen Fahrzeugkörper
zwischen diesen Stationen befördert.
1. Procédé de revêtement d'un véhicule par une peinture, le procédé comprenant une étape
de pulvérisation au cours de laquelle la peinture est pulvérisée sur la carrosserie
du véhicule afin qu'elle forme un feuil de peinture, et comprenant en outre une étape
de cuisson dans laquelle la carrosserie du véhicule est maintenue à une température
ambiante élevée pendant qu'elle subit une rotation, avec toute la peinture qu'elle
porte, autour d'un axe horizontal et jusqu'à ce que la peinture soit cuite, caractérisé
en ce que la peinture pulvérisée sur la carrosserie de véhicule est d'un type qui
devient fluide à la température utilisée dans l'étape de cuisson, en ce que, au cours
de l'étape de pulvérisation, la peinture est pulvérisée sur la carrosserie du véhicule
avec une épaisseur de feuil qui dépasse une épaisseur de seuil du feuil à laquelle
une déformation de la peinture se produit au moins sur une surface de la carrosserie
du véhicule qui est disposée verticalement, et en ce que la carrosserie du véhicule
est entraînée en rotation autour d'un axe horizontal au cours de l'étape de cuisson
à une vitesse suffisamment élevée pour que la déformation du feuil de peinture formé
sur la carrosserie du véhicule, qui pourrait être due à la pesanteur, soit pratiquement
évitée, la vitesse étant suffisamment faible pour que la déformation du feuil de peinture
sous l'action de la force centrifuge soit évitée. -
2. Procédé de revêtement selon la revendication 1, dans lequel la carrosserie du véhicule
est entraînée en rotation dans le sens des aiguilles d'une montre et dans le sens
contraire des aiguilles d'une montre.
3. Procédé de revêtement selon la revendication 2, dans lequel la carrosserie du véhicule
est entraînée en rotation de façon continue dans le sens des aiguilles d'une montre,
puis dans le sens contraire des aiguilles d'une montre.
4. Procédé de revêtement selon la revendication 2, dans lequel la carrosserie du véhicule
est entraînée en rotation en alternance dans le sens des aiguilles d'une montre et
dans le sens contraire des aiguilles d'une montre.
5. Procédé de revêtement selon la revendication 2, dans lequel la carrosserie du véhicule
est entraînée en rotation dans les deux sens, chaque fois d'un angle d'au moins 90°.
6. Procédé de revêtement selon l'une quelconque des revendications 1 à 5, dans lequel
la carrosserie du véhicule qui doit être revêtue porte un revêtement intermédiaire.
7. Procédé de revêtement selon la revendication 1, dans lequel la carrosserie du véhicule
est entraînée en rotation dans un seul sens.
8. Procédé de revêtement selon la revendication 7, dans lequel la carrosserie du véhicule
est entraînée constamment en rotation.
9. Procédé de revêtement selon la revendication 7, dans lequel la carrosserie du véhicule
est entraînée en rotation par intermittence.
10. Procédé de revêtement selon l'une des revendications 1 à 9, dans lequel la peinture
pulvérisée sur la carrosserie du véhicule est une peinture en poudre.
11. Procédé de revêtement selon la revendication 10, dans lequel la peinture en poudre
est pulvérisée avec un feuil dont l'épaisseur dépasse l'épaisseur de seuil du feuil
d'environ 80 µm.
12. Procédé de revêtement selon la revendication 10 ou 11, dans lequel la déformation
permise est inférieure à 2 mm.
13. Procédé de revêtement selon l'une quelconque des revendications 10 à 12, dans lequel
la carrosserie du véhicule est entraînée en rotation au moins dans la partie initiale
de l'étape de cuisson.
14. Procédé de revêtement selon l'une quelconque des revendications 1 à 13, dans lequel
la carrosserie du véhicule est maintenue pratiquement fixe pendant l'étape de pulvérisation.
15. Procédé de revêtement selon l'une quelconque des revendications 1 à 14, dans lequel
la carrosserie du véhicule est entraînée en rotation dans une étape préparatoire,
avant l'étape de pulvérisation, afin que les matières étrangères soient chassées de
la carrosserie du véhicule.
16. Procédé de revêtement selon la revendication 15, dans lequel la carrosserie du véhicule
est transportée par un chariot rotatif, de l'étape préparatoire à l'étape de cuisson.
17. Procédé de revêtement selon la revendication 16, dans lequel la carrosserie du véhicule
est transportée sur le même chariot de l'étape préparatoire à l'étape de cuisson.
18. Procédé de revêtement selon l'une quelconque des revendications 1 à 17, dans lequel
l'axe horizontal de rotation passe par le centre de gravité de la carrosserie du véhicule.
19. Procédé de revêtement selon la revendication 1, dans lequel l'axe horizontal de rotation
est disposé dans la direction longitudinale de la carrosserie du véhicule.
20. Procédé de revêtement selon l'une quelconque des revendications 1 à 19, dans lequel
la carrosserie du véhicule est entraînée en rotation à une vitesse inférieure' ou
égale à 380 cm/s, cette vitesse étant mesurée dans une partie d'extrémité radialement
externe de la carrosserie du véhicule.
21. Procédé de revêtement selon la revendication 1, dans lequel l'étape de cuisson est
la seule étape de séchage de la peinture.
22. Procédé de revêtement selon la revendication 1, dans lequel la peinture pulvérisée
sur la carrosserie du véhicule est une peinture thermodurcissable.
23. Procédé de revêtement selon la revendication 22, dans lequel le séchage de la peinture
portée par la carrosserie du véhicule comprend une étape de fixage puis une étape
de cuisson, et la carrosserie du véhicule est maintenue, pendant l'étape de fixage,
à une température ambiante inférieure à la température ambiante utilisée pendant l'étape
de cuisson, et la carrosserie du véhicule est entraînée en rotation autour de l'axe
horizontal pendant l'étape de fixage également.
24. Procédé de revêtement selon la revendication 22 ou 23, dans lequel la peinture thermodurcissable
forme un revêtement ayant une épaisseur de feuil qui dépasse son épaisseur de seuil
de feuil de 40 µm.
25. Procédé de revêtement selon l'une quelconque des revendications 22 à 24, dans lequel
la déformation permise est inférieure ou égale à 2 mm.
26. Procédé de revêtement selon la revendication 25, dans lequel la carrosserie du véhicule
est entraînée en rotation à une vitesse qui provoque une déformation à une vitesse
maximale de déformation à laquelle la peinture se déforme à cause de l'écoulement
de chaleur provoqué au cours de l'étape de cuisson.
27. Appareil de revêtement incorporé à une ligne de revêtement d'une carrosserie de véhicule
par une peinture, comprenant un dispositif de pulvérisation de la peinture sur la
carrosserie du véhicule afin qu'elle forme un feuil de peinture, un dispositif (D,
D') de transport de carrosserie destiné à supporter la carrosserie du véhicule et
à la transporter le long de la ligne de revêtement, et un dispositif (1) d'entraînement
en rotation associé au dispositif de transport de la carrosserie et destiné à faire
tourner la carrosserie du véhicule autour d'un axe pratiquement horizontal à un poste
de séchage (P3, P4), comprenant un poste de cuisson (P4), afin que la peinture durcisse,
caractérisé en ce que le dispositif de pulvérisation permet la pulvérisation d'une
peinture d'un type qui devient fluide à la température utilisée au poste de cuisson,
en ce que le dispositif de pulvérisation peut être commandé afin qu'il pulvérise la
peinture avec une épaisseur de feuil qui dépasse une épaisseur de seuil de feuil à
laquelle une déformation de la peinture se produit, au moins sur une surface de carrosserie
de véhicule disposée verticalement, et en ce que le dispositif (1) d'entraînement
en rotation, dans le poste de cuisson, est destiné à faire tourner la carrosserie
du véhicule à une vitesse suffisamment élevée pour que la déformation du feuil de
peinture portée par la carrosserie du véhicule et due à la pesanteur soit évitée,
et suffisamment faible pour que la déformation du feuil de peinture sous l'action
de la force centrifuge soit évitée.
28. Appareil de revêtement selon la revendication 27, dans lequel la carrosserie du véhicule
est supportée de manière que l'axe de rotation horizontal (l) soit disposé dans la
direction longitudinale de la carrosserie du véhicule.
29. Appareil de revêtement selon la revendication 27 ou 28, dans lequel le dispositif
(1) d'entraînement en rotation fait tourner la carrosserie du véhicule à une vitesse
inférieure ou égale à 380 cm/s.
30. Appareil de revêtement selon l'une quelconque des revendications 27 à 29, dans lequel
le dispositif (D) de transport de carrosserie comprend un dispositif (26 à 29) de
support de la carrosserie du véhicule afin qu'elle puisse tourner autour de son axe
horizontal, un dispositif' (K1, K2) d'entraînement en rotation qui comporte un dispositif
à ressort (63, 64 ; 64-3) comme source d'entraînement en rotation, et un mécanisme
de transmission (L ; 85 à 87 ; 140 à 149) destiné à transmettre une force de rappel
du dispositif à ressort comme force de rotation au dispositif de support.
31. Appareil de revêtement selon la revendication 30, dans lequel la ligne de revêtement
a un dispositif (62) d'accumulation de force destiné à accumuler la force de rappel
du dispositif à ressort.
32. Appareil de revêtement selon la revendication 30 ou 31, dans lequel le dispositif
(D) de transport de carrosserie comporte en outre un mécanisme (Z) de contrôle de
vitesse destiné à contrôler la vitesse de rotation de la carrosserie du véhicule lorsqu'elle
est entraînée par le dispositif d'entraînement en rotation, à l'intérieur de la plage
de vitesses.
33. Appareil de revêtement selon l'une quelconque des revendications 30 à 32, dans lequel
un dispositif (136) de commutation de couple est destiné à commuter le couple d'entraînement
du dispositif à ressort d'une valeur relativement élevée au début de la rotation de
la carrosserie du véhicule à une valeur plus faible après le début de la rotation.
34. Appareil de revêtement selon l'une quelconque des revendications 30 à 32, dans lequel
le dispositif à ressort comporte un premier ressort (64) destiné à assurer le début
de la rotation et un second ressort (64) destiné à poursuivre la rotation.
35. Appareil de revêtement selon l'une quelconque des revendications 27 à 34, dans lequel
un mécanisme à organe d'équilibrage (41 à 44) est destiné à assurer un déplacement
vers une coïncidence en pratique de l'axe horizontal de rotation et du centre de gravité
de la carrosserie du véhicule supportée par le dispositif de transport de carrosserie.
36. Appareil de revêtement selon l'une quelconque des revendications 27 à 35, dans lequel
le dispositif de transport de carrosserie comporte en outre un mécanisme (R) d'arrêt
monté sur le dispositif de transport de carrosserie et destiné à suspendre la rotation
de la carrosserie du véhicule à une position prédéterminée en rotation lors de son
entraînement en rotation à un poste de fixage (P3) du poste de séchage (P3, P4).
37. Appareil de revêtement selon la revendication 27, dans lequel le dispositif (D') de
transport de carrosserie comporte un dispositif (26 à 29) de support de la carrosserie
du véhicule afin qu'elle puisse tourner autour d'un axe horizontal, un organe rotatif
denté (233) étant raccordé à la carrosserie du véhicule supportée par le dispositif
de support, et un organe allongé (234) est en prise avec l'organe rotatif denté et
est mobile le long d'un passage de transport (23) sur lequel est transporté le dispositif
de transport.
38. Appareil de revêtement selon la revendication 37, dans lequel l'organe rotatif denté
est un pignon d'engrenage ou à chaîne, et l'organe allongé est une crémaillère ou
une chaîne.
39. Appareil de revêtement selon la revendication 27, dans lequel le dispositif (D') de
transport de carrosserie comprend un dispositif de support (224 à 227) destiné à supporter
la carrosserie du véhicule afin qu'elle puisse tourner autour de l'axe horizontal,
et un mécanisme convertisseur (231) raccordé à la carrosserie du véhicule lorsqu'elle
est supportée par le dispositif de support et destiné à transformer un déplacement
du dispositif de transport de carrosserie en un mouvement de rotation de la carrosserie
du véhicule.
40. Appareil de revêtement selon la revendication 39, dans lequel le mécanisme convertisseur
comporte un organe rotatif denté (233) supporté afin qu'il puisse tourner par le dispositif
de transport de carrosserie et destiné à être raccordé à la carrosserie du véhicule
supportée par le dispositif de support, et un organe allongé (234) disposé le long
du passage de transport (23) du dispositif de transport de carrosserie de manière
fixe et en prise avec l'organe rotatif denté (233).
41. Appareil de revêtement selon la revendication 39, dans lequel le passage de transport
(23) du dispositif (D') de transport de carrosserie comporte une source motrice (25)
destinée à déplacer le dispositif de transport de carrosserie, et un dispositif d'entraînement
(234) placé parallèlement à la source motrice (25) et destiné à transmettre une force
d'entraînement en rotation du mécanisme convertisseur (231).
42. Appareil de revêtement selon l'une quelconque des revendications 27 à 41, dans lequel
le dispositif de pulvérisation est destiné à appliquer une peinture qui provoque une
circulation de chaleur à la température ambiante au poste de cuisson et qui ne se
déforme que sous l'action de cette circulation de chaleur.
43. Appareil de revêtement selon la revendication 42, dans lequel le dispositif de pulvérisation
est destiné à pulvériser une peinture en poudre.
44. Appareil de revêtement selon la revendication 43, dans lequel le dispositif de pulvérisation
est destiné à appliquer la peinture en poudre avec une épaisseur de feuil qui dépasse
l'épaisseur de seuil du feuil d'environ 80 µm.
45. Appareil de revêtement selon l'une quelconque des revendications 42 à 44, dans lequel
le dispositif de transport de carrosserie est entraîné en rotation à une vitesse supérieure
ou égale à une vitesse maximale de déformation du feuil de peinture au poste de cuisson.
46. Appareil de revêtement selon l'une quelconque des revendications 27 à 41, dans lequel
le dispositif de pulvérisation est destiné à pulvériser une peinture qui se déforme
au cours de l'étape de fixage au poste de séchage ainsi que pendant l'étape de cuisson
au poste de cuisson,' et dans lequel la carrosserie du véhicule est entraînée en rotation
pratiquement à la même vitesse au poste de fixage et au poste de cuisson.
47. Appareil de revêtement selon la revendication 46, dans lequel le dispositif de pulvérisation
est destiné à pulvériser une peinture de type thermodurcissable.
48. Appareil de revêtement selon la revendication 47, dans lequel le dispositif de pulvérisation
est destiné à pulvériser la peinture thermodurcissable avec une épaisseur de feuil
qui dépasse l'épaisseur de seuil de feuil d'environ 40 µm.
49. Appareil de revêtement selon la revendication 46 ou 47, dans lequel la carrosserie
du véhicule est entraînée en rotation à une vitesse égale ou supérieure à la plus
grande des vitesses de déformation de la peinture aux postes de fixage et de cuisson.
50. Appareil de revêtement selon l'une quelconque des revendications 46 à 49, dans lequel
le dispositif de transport de carrosserie peut être transporté entre le poste de fixage
(P3) et le poste de cuisson (P4), si bien qu'un dispositif de transport d'une carrosserie
unique transporte une carrosserie unique de véhicule entre ces postes.