[0001] This invention relates to transport apparatus for conveying an article through a
production line in which the article is to be subjected to treatment by dipping.
[0002] The production line in conjunction with which the transport apparatus is to be used
may be a continuous process dip enamelling line. Up until now, the process followed
in industry for enamelling steel parts that are to be vitrified has been carried out
in three stages that can be perfectly differentiated from one another, these being
pickling or pretreatment, the application of the enamel, and vitrification. It may
be said that, in the pickling process, the basic stages as performed in succession
to one another are degreasing, rinsing, etching (pickling proper), rinsing, neutralizing,
and passivating, so that the steel parts are then ready to go on to the stage wherein
the enamel is applied.
[0003] Looking back in time, it may be said that the methods followed in each one of these
stages have been constantly developed in pursuit of two primordial purposes, which
are to make it feasible that the said stages can be adapted to the morphological and
specific properties of each part to be enamelled whatever they may be, and to rationalize
the work so as to achieve a reduction in labour requirements and power consumption,
and at the same time increase productivity.
[0004] Along these lines of development, the pickling or anc- illiary operation, which in
principle was done by dipping using hand-controlled hoist blocks, was suddenly revolutionized
with the appearance of spray tunnels, with the parts being mechanically conveyed,
which enabled very high production rates per man to be achieved, with technically
satisfactory results too. Nonetheless, this system is now no longer considered to
be ideal since it involves a high maintenance cost and a similarly high power consumption
in operation, apart from the initial cost of the installation itself.
[0005] In order to overcome these disadvantages there has now been a return, in part at
least, to the original dipping system, employing programmed-cycle cranes, although
this system does frequently give rise to difficulties with liquids being transferred,
which difficulties are hard to obviate.
[0006] The same may be said of the enamel application stage, where there has been successive
development
' from hand dipping to electrostatic aerographic application and, in modern times,
to electrophoretic and dry powder application.
[0007] For all these reasons then, and very much in spite of all technical advances, dipping
with greater or lesser mechanical assistance, still persists and competes with all
modern spray methods embodying more advanced technology, even to the extent of the
old dipping method having no substitute in certain cases, owing to the efficiency
that can be achieved with it, and its economy.
[0008] In any case, whichever system is used for performing the stages mentioned above,
it has been found that the greatest difficulties arise as the result of the actual
morphology of the part to be processed..In this regard it is found that in the above-mentioned
stages involving pickling, drying, rinsing, enamelling, and so forth, those parts
possessing indentations or odd shapes in particular, each require to be placed in
a very special position so as to avoid air being trapped, enamel being restricted,
and so on, and this in turn means that hand labour needs to be used at various places
in the enamelling plant in order to position each part in the most favourable position
for the execution of each stage or phase, this being all the more true when it is
realized that any one part may require to be placed in two opposing positions in order
for any two stages or phases to be satisfactorily accomplished.
[0009] The transport system we are concerned with in this invention does, by overcoming
all these difficulties, provide a definitive solution, allowing the enamelling installation
advantageously to become part of a continuous production line and to operate in conjunction
with the dipping method for pickling, in addition to enabling the enamel too to be
applied by dipping, where all this process is accomplished without any manual intervention
being needed between the two stages, as has been the case up to now with all known
installations.
[0010] In general terms the present invention provides transport apparatus for conveying
an article through a production line in which the article is to be subjected to treatment
by dipping, the apparatus comprising a rigid track defining a closed circuit, an arm
which is adapted to hold the article and which is movably mounted on the track, means
for moving the arm along the track, means for swinging the arm in a plane transverse
to its direction of motion along the track, and means for turning the arm about its
longitudinal axis.
[0011] In an installation for continuous dipping treatment of parts to be enamelled the
pieces of equipment used in each one of the stages in a conventional dipping treatment
plant are arranged opposite: a rigid cyclic structure which serves the purpose of
supporting the arm to hold the part being treated, and moreover there are means on
top of the structure that make the holding arm travel, means to provide said arm with
at least one revolving motion about its own axis, and with a revolving motion at right
angles to its direction of travel, where the extent of these motions is in accordance
with the shapes of the parts to be processed in the plant.
[0012] It is due to the said swinging and turning motions that the article being processed
can be made to vary its position while travelling and entering and leaving all the
baths that are necessary for preparing its surface for enamelling, where at the same
time the revolving motion about the axis of the holding arm avoids there being any
air trapped inside the article and enables any trapped liquid to run out therefrom.
The article being processed can then be made to travel into a drying length or stage,
and afterwards into a cooling stage so that the enamel can then forthwith be applied
by dipping. Upon emerging from the enamel dip, the article travels along a further
drying length and simultaneously the supporting arm undergoes suitable motions about
itself so as to achieve the draining of any liquid that remains therein, whereupon
it finally reaches a point where. the article is withdrawn and removed to the conveyor
which will take it to the vitrifying stove, while the holding arm then remains free
and ready to be returned to recommence the cycle with a further article.
[0013] Any one of a number of different sysstems may be employed for achieving the said
motions, and tie use of one or another will depend upon such variables as the weight
of the article to be enamelled, its geometrical features, the degree of perfection
required in the process, the hourly production rate, and so forth. In particular,
this consideration may govern
The radii of curvaturein lerge installations may lead to there being wasted space
between the two parallel lengths. end to avoid this a closed rail conveyor system
is installed instead. being provided with pulling connection placed at a suitable
difference, any means tc guide the holding arm optionally towards whichever side is
required.
[0014] With all the above features, and upon being a continuous and enclsed installation,
the folloring advantages are achieved:
C. Enamel is applied by dipping, which, as was stated at the outset, is an economical
system with a minimum wastage of enamel, and in addition it generates no pollution.
D. No need for labour between the stages where the pickling takes place and where
the enamel is applied.
E. Significant saving in floor space in comparison to the requirements of installations
at present known.
F. Finally,the system being dealt with here requires nothing at all in the way of
large capital expenditure.
[0015] The invention will be described further, by way of example only, with reference to
the accompanying drawings. in which:
Figure 1 is a transverse section through transport apparatus for conveying an article
through a dip enamelling production line, one bath of which is shown in cross section;
and
FIgure 2 is a schematic plan view of the production line, the stages of the production
process being indicated.
[0016] When a steel part 14 travels from the dip in a bath 12 belonging to any stage at
all in the production process , to thefllowing bath. it tends to carry with it products
from the previous stage, which are normally harmful to the elements in the following
stage, and they may even contaminae the actual products used for the treatment. Furthermore,
owing to the characteristic shape that each part 1- possesses, the different products
used for the treasment will tend to remain to a greater degree on sore areas more
than on others on the part, which would cause stresses that give rise to cracking
and deterioration of the enamel and hence its becoming useless. These difficulties
have in the past meant that skilled labour has had to be used at each one of the stages
in the process in order to arrange the part manually in the most favourable position
and thus obviate the problems de
3- cribed above.
[0017] According to the present invention, a rigid structure on track 11 defines a close
circuit along which a carriage 1 is driven by conventional travelling means (not illustrated).
A support or bearing 4 for an arm 3 is attached to the carriage 1 through a pivot
shaft 5, and the arm 3 is fitted at one of its ends with a tool 2 for holding or grasping
the part 14.
[0018] As has been mentioned above,-the part 14 is required to undergo a series of motions
from one position to another as it travels from one stage to another, and in each
one of these latter. The said motions and positions are in principle achieved through
the swinging of the holding arm 3 the plane of the drawing (Fig 1), and the turning
of the erm 3 about its own longitudinal axis X-X
1. For this purpose, a wave shaped slide surface or guideway 7 is provided on the structure
11, having indentations or protrusions, or similar parts, to cause the said rotation
when a
[0019] construction of the equipment, by the sliding or engagement in certain areas on the
actual slide surface or guidaway 7 of the roller 6 at the end of the holding arl 3.
[0020] A counterweight 10 is provided in order to make the holding arm 3 return to its original
position after having revolved about its axis, or after having been swung upwards
from the position shown in Fig 1.
[0021] In a further practical construction, gear wheels and racks are provided along the
slide surface or guideway 7 so as to make the holding arm 3 return to its initial
position.
[0022] It will be appreciated that there is a multitude of ways and means that can be thought
of, or which have already been thought of, so as to achieve identical motions to those
described.
[0023] Racks and stops 8 may be used instead of, independently form, or in combination with
the aforementioned components, as may be the case for example where the circuit is
zigzag in shape when viewed from above, and it is desired to utilize the space between
the two parallel sides, wherein directional racks would be employed inside the space,
these being already known, for the purpose of directing the rotation of the arm towards
the inside of the said space at the reouired moment.
[0024] The whole installation is integrated into a mair structure which holds the track
for the conveyor chain, and additionally accommodates the bath as required for dipping.
The process stages are shown in Fig 2.
[0025] Differential detectors are moreover provided, whose purpose is to programme selective
dipping in whatever bath is required by the parts to be processed.
[0026] A hood, fitted with windows to allow observation and control, and provided with permanent
extraction equipment, is arranged over the baths which might emit gases or fumes.
[0027] The installation is completed with pumps and valves in the circuits that require
them, a length to facilitate loading and unloading the part to be processed, and another
length to facilitate washing the tool 2 used to hold the part, once it has been unloaded
and prior tc commencement of the following cycle.
1. Transport apparatus for conveying an article through a production line in which
the article is to be subjected to treatment by dipping, the apparatus comprising a
rigid track (11) defining a closed circuit, an arm (3) which is adapted to hold the
article (14) and which is movably mounted on the track (11), means for moving the
arm (3) along the track (11),means for swinging the arm (3) in a plane transverse
to its direction of motion along the track (11), and means for turning the arm (3)
about its longitudinal axis (X-X1).
2. Transport apparatus as-claimed in claim 1, in which the arm swinging means comprises
a guideway (7) which is fixed to the track (11) and extends along the track (11),
the guideway (7) having indentations and protrusions, the arm (3) having at least
one part (6) which cooperates with the guideway (7) in order to cause swinging of
the arm (3).
3. Transport apparatus as claimed in claim 2, in which the said part (6) engages with
given zones of the guideway (7) in order to cause selective turning of the arm (3)
about its axis (X-X1).
4. Transport apparatus as claimed in any one of claims 1 to 3, in which the arm (3)
is mounted in a bearing (-) allowing the arm (3) to turn about its axis (X-X1), the bearing (4) being movably mounted on the track (11).
5. Transport apparatus as claimed in any of claims 1 to 4. in which the arm (3) is
mounted on a pivot shaft (5) allowing the arm (3) to swing in a plane transverse to
its direction of motion along the track (11).
6. Transport apparatus as claimed in any of claims 1 to 5, in which the arm (3) can
be swing through more than 180°.
7. Transport apparatus as claimed in any of claims 1 to 6, in which the arm 3 carries
a counterweight (10) urging the arm (3) to return to a given position after the arm
(3) has been swung or turned from that position.
8. An installation for treating an article, comprising a production line in which
the article is to be subjected to treatment by dipping, characterised by transport
apparatus as claimed in any preceding claim, for conveying the article through the
production line.
9. An installation as claimed in claim 8, in which the production line is a dip enamelling
line.