[0001] The invention refers to machines for spraying paint or other treatment product onto
articles made of wood or other material with a mainly flat extension, such as panels
for example, which move along resting on a horizontal conveyor which transports the
said panels so that they pass through a booth which is usually at a lower pressure
than the exterior and inside which a carousel or a transfer device operates with vertical
axes of rotation, said carousel or transfer device causing a succession of guns delivering
the treatment product to pass over the panels. The spray guns of these types of machines
are connected to a pumping circuit which draws the paint from a fixed supply station
and which at present is provided on the delivery circuit with a rotating distributor
which has costly seals able to withstand the particularly aggressive chemical attack
of the components of the product to be distributed. When these same types of machines
are required to perform intermittent processing operations, during which the carousel
or the transfer device with the guns remain rotating or when those machines are used
to perform continuous processing operations which are prolonged over time, the rotating
joint of the paint supply circuit, which is situated downstream of the pump and therefore
along the high-pressure branch of the said supply circuit, may be subject, as a result
of friction and pressure, to the small increases in temperature which trigger a catalysis
process in the paint used, with rapid deterioration of the said rotating joint which
for this reason must undergo frequent maintenance, with stoppage of the machine and
with all the cost-related drawbacks which arise from this condition. The invention
intends to overcome these and other drawbacks with the following proposed solution.
The ends of the supply pipes of the spray guns are connected to a header provided
with a vertical supply tube which is made to rotate in a synchronised manner and in
the same direction as the gun assembly mounted on the carousel or the transfer device
and this supply tube is connected to a flexible pipe which, after a short curved and
upward trajectory, is arranged horizontally and with this section is supported rotatably
by special means and which with the other end of its curved and downward section is
connected to a hollow and vertical hub in turn connected to the delivery of a pump
arranged vertically and on a vertical support integral and coaxial with the said hub
which is made to rotate by special means at the same speed of rotation as the supply
tube, but in the opposite direction, while with its bottom draw-off the said pump
is immersed inside the container of paint which is fixed. With this solution the rotating
joint is completely eliminated and all the problems associated with it are eliminated
and the paint is continuously mixed and kept fluid by the draw-off of the pump. Further
characteristic features of the invention and the advantages arising from it will emerge
more clearly from the following description of some preferred embodiments thereof
illustrated purely by way of a non-limiting example in the figures of the accompanying
illustrative plate in which:
- Fig. 1 is a schematic view of a machine with the guns mounted on a transfer device,
improved according to the invention and cross-sectioned in the direction of feeding
of the panels;
- Fig. 2 shows details as shown along the cross-section II-II of Figure 1;
- Fig. 3 shows a constructional variant of the paint supply circuit.
[0002] In Figure 1, C denotes the booth of the spraying machine provided at its ends with
gates P1 and P2 which are aligned with each other and which have, connected in the
vicinity thereof, the ends of a horizontal conveyor T inside the said booth and external
conveyors T1 and T2 which perform feeding of the panels Z which must be painted by
an assembly of spray guns G mounted on a carousel or a transfer device H inside the
booth C, which is supported for example by a gantry structure L and which by suitable
means, not shown, is made to rotate on its vertical axis or axes, so that the said
guns are made to perform transverse movements in opposite directions over the panels
Z which move along the conveyor T such that, as a result of the combination of these
movements, there is a correct distribution of the paint or other product sprayed by
the said guns on the said panels. Outlets connected to a suction circuit via special
filters for eliminating the haze and gases resulting from the painting stage are usually
arranged on the sides of the conveyor T, while, inside the booth C, clean outside
air is supplied into the said booth via false ceiling structures A. The suction created
by means of the said circuit is usually such that air enters from the outside via
said gates P1 and P2. According to the invention, the top of the booth C has, emerging
rotatably from it, a vertical delivery tube 1 which, inside the transfer machine,
as can be seen in the example of Figure 1, is situated inside the central part of
the said transfer device, in a position equidistant from the end pinions for driving
the parallel chains of the said transfer device and with its bottom closed end is
connected to means 2 which cause it to rotate in the same direction and at the same
speed as the axis of the said pinions. On the bottom part the tube 1 supports integrally
and communicates with a small hollow header 3 inside which the ends of the flexible
paint delivery pipes 4 are connected to the guns G. If the guns of the spraying machine
were mounted differently on a vertical-axis rotating carousel, the said tube 1 would
be arranged coaxially inside the said carousel and could coincide with the rotational
shaft of the latter, while the header 3 in this case could be arranged on the bottom
end of the carousel shaft and the supply pipes 4 of the guns could depart from the
latter. 5 denotes an optional support which is fixed, for example, to the booth C
and helps rotatably support the supply tube 1. Laterally with respect to the booth
C, a fixed protection chamber 6 is provided outside the latter, said chamber having
a height which is slightly less than that of the said booth C and being provided with
a door 106 which has a meshwork screening, and the upper wall of this chamber has,
rotatably mounted thereon, a vertical hub 7 which supports inside the said chamber
6 a cage 8 arranged so as to circumscribe and carry fixed and coaxially a pump 9,
for example of the volumetric and pneumatic type, which is oriented downwards and
with its own draw-off 109, which can be adjusted in terms of its heightwise position
using a control device and using means not shown in that they may be easily realized
by a person skilled in the art, is immersed inside the container 10 with the paint
to be sprayed, situated in a fixed and sufficiently central position on the bottom
of the chamber 6. The delivery of the pump 9 is connected by means of the pipe 21
to the bottom end of the said hub 7 which is axially hollow and which, on the outside
of the axial cavity occupied by the paint, has another cavity which with the bottom
end is connected to a pipe 11 for supplying to the pump compressed air necessary for
operation thereof, while with the top end it is connected to the fixed part 12 of
a rotating joint to which the end of the pipe 13 supplying the compressed air is connected.
The top end of the hub 7 is fixed to the ends of at least one flexible high-pressure
tube, not shown, preferably housed inside a tubular protection sheath 14, which is
also flexible and for example of the corrugated type, and this sheath and tube assembly
follows a path with a first upward section 114, then a first curve 214 substantially
at 90º, then a straight and substantially horizontal section 314 (see below) and finally
a second downward curve 414 at 90º, at the end of which the said sheath and tube assembly
14 is fixed to the top end of the supply tube 1. The horizontal section 314 of the
sheath 14 is rotatably supported by a channeled guide 15 which is open upwards and
fixed by means of brackets 115 onto the booth C and provided at the ends with retaining
bridge-pieces 215, as can be seen from the example according to Figure 2. The hub
7 and the tube 1 are connected together by means of any kinematic chain of the positive
type which causes the rotation of these components at the same speed and in opposite
directions. Purely by way of a non-limiting example, the said kinematic chain may
comprise a first positive drive 16 for the movement which is connected to the top
end of the supply tube 1 and which with the other end is connected to a movement reversal
device 17 connected to a second positive movement drive 18 which actuates the hub
7. It is understood that other suitable parts may be used to connect kinematically
the supply pipe 1 to the hub 7, for example angular type movement transmission systems.
If necessary, an electric motor may be provided at any point of the said kinematic
chain, said motor operating the carousel or the transfer device with the guns or having
its shaft connected electrically to the motor of the spraying machine. It is clear
how, following rotation at the same speed and in the opposite direction of the vertical
ends of the flexible sheath 14 with the associated internal tubes, owing to the synchronised
rotation of the supply tube 1 in one direction and the rotation of the pump 9 in the
opposite direction, the said sheath 14 and the associated inner tubes are made to
rotate without any twisting about their longitudinal axis and are able to supply the
paint or other product to the guns of the spraying machine, without the intervening
arrangement of rotating joints and without the problems associated with them. This
solution also offers the advantage that the draw-off 109 of the pump rotates inside
the paint container 10 and keeps the paint itself suitably mixed and fluid. Figure
3 shows a constructional variant of the invention according to which the draw-off
109 of the pump does not have any heightwise adjustments and draws from the paint
container 10 which may be situated outside the chamber 6, via a rotating coaxial joint
19 and by means of at least one fixed tube 20, substantially eliminating the drawbacks
of the known art since the said joint operates at low pressure.
1. Apparatus for supplying the product to be sprayed to spraying machines of the rotating
type, having the guns mounted on a carousel or on a transfer device, in which the
ends of the pipes (4) supplying the spray guns (G) are connected to a header (3) provided
with a vertical supply tube (1) which is made to rotate by suitable means (2) in a
synchronized manner and in the same direction as the gun assembly mounted on the said
carousel or transfer device and this supply tube (1) is connected to at least one
flexible pipe (14) which, after a short curved and upward trajectory (414), is arranged
horizontally with a middle section (314) rotatably supported by special means (15)
and which with the other end of its curved and downward section (214, 114) is connected
to a hollow and vertical hub (7) in turn connected to the delivery of a pump (9) of
any suitable type, arranged vertically on a vertical support (8) integral and coaxial
with the said hub (7) which is made to rotate by special means at the same speed as
the said supply tube (1), but in the opposite direction, while with its bottom axial
draw-off the said pump (9) is immersed inside the fixed container (10) with the product
to be sprayed, consisting of paint for example, all of which so that the said flexible
pipe (14) rotates without twisting about its longitudinal axis and is able to supply
the paint or other product to the guns of the spraying machine, without the intervening
arrangement of rotating joints and without the problems associated with them.
2. Apparatus according to Claim 1), in which the said flexible pipe (14) consists of
a protective sheath for example of the corrugated type having, arranged inside it,
one or more high-pressure tubes passed through by the paint or other product to be
supplied to the spray guns.
3. Apparatus according to Claim 1), in which the draw-off (109) of the pump (9) rotates
inside the container (10) of paint and keeps the said paint suitably mixed and fluid.
4. Apparatus according to Claim 1), in which laterally with respect to the booth (C)
of the spraying machine, a fixed protection chamber (6) is provided outside the latter,
said chamber having a height which is slightly less than that of the said booth (C)
and being provided with a door (106) for example with a meshwork screening, and the
upper wall of this chamber has, rotatably mounted thereon, the vertical hub (7) which
supports inside the said chamber (6) a coaxial cage (8) arranged so as to circumscribe
and carry fixed a pump (9) which is oriented downwards and which with its own bottom
coaxial draw-off (109) can be adjusted in terms of its heightwise position using suitable
means and is immersed inside the container (10) with the paint to be sprayed, situated
in a fixed and sufficiently central position on the bottom of the said chamber (6),
the delivery of the said pump (8) being connected to the bottom end of the said hub
(7) in turn connected to one end of the said flexible pipe (14).
5. Apparatus according to Claim 2), in which the pump (9) is for example of the volumetric
and pneumatic type and the said hub (7) is axially hollow and, outside the axial cavity
passed through by the paint, has another cavity which with the bottom end is connected
to a pipe (11) which supplies to the pump the compressed air necessary for operation
thereof, while with the top end the said outer cavity is connected to a rotating joint
which with its fixed part (12) is connected to the fixed pipe (13) supplying the compressed
air.
6. Apparatus according to Claim 3), in which the said hub (7) and the said pipe (1) supplying
the guns (G) of the spraying machine are connected together by means of any kinematic
chain of the positive type which causes rotation of the said components at the same
speed and in opposite directions, for example by means of a first positive movement
drive (16) which is connected to the top end of the said supply tube (1) and with
the other end is connected to a movement reversal unit (17) connected to a second
positive movement drive (18) which actuates the said hub (7) or via equivalent means
which use for example angular movement transmission systems.
7. Apparatus according to Claim 5), in which, at any point of the said kinematic chain
which connects together the hub (7) and the supply tube (1), an electric motor may
be provided, said motor operating the carousel or the transfer device with the guns
having its shaft connected electrically to the actual motor of the spraying machine.
8. Apparatus according to Claim 3), characterized in that, according to a constructional variant, the draw-off (109) of the pump is devoid
of heightwise adjustments and draws from the container (10) of paint, which may be
situated outside the protection chamber (6), via a rotating joint (19) coaxial with
the said draw-off and by means of at least one fixed tube (20).
