Note: Descriptions are shown in the official language in which they were submitted.
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Device for curing a coating of an object, the coating
consisting of a material that cures under electromagnetic
radiation, in particular of a W lacquer or a thermally
curable lacquer
The invention relates to a device for curing a coating of
an object, in particular a vehicle body, the coating con-
sisting of a material that cures under electromagnetic
radiation, in particular of a UV lacquer or a thermally
s curable lacquer, comprising
a) at least one emitter generating electromagnetic ra-
diation;
b) a conveying system which conveys the object into the
vicinity of the emitter and away from it again.
to Lacquers that cure under UV light have previously been
used primarily for lacquer coating sensitive objects, for
example wood or plastics material. In this case the ad-
vantage of these lacquers being able to be polymerised at
very low temperatures is particularly useful. As a re-
15 cult, the material of the objects is prevented from dis-
integrating or gas emission. However, curing of coating
materials under UV light has yet further advantages which
accordingly make this coating process interesting for use
in other areas as well. These advantages are, in particu-
20 lar, the short curing time, which is immediately re-
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flected, in particular in coating processes which operate
in a continuous cycle, in a reduction in the plant length
which is connected with enormous cost savings. At the
same time the apparatus with which the gases to be intro-
s duced into the interior of the device are conditioned,
can be reduced in size, and this also contributes to cost
savings. Finally, the low operating temperature - even
with objects which could themselves tolerate higher cur-
ing temperatures per se - is advantageous for reasons of
to conserving energy and, more precisely, thermal energy in
particular.
Many of the objects which one would like to be able to
coat with UV-curing materials, such as vehicle bodies,
have a very uneven, often three-dimensionally curved sur-
is face, so it is difficult to introduce these objects into
the radiation region of a UV emitter such that all sur-
face regions have approximately the same spacing from the
UV emitter and the UV radiation substantially strikes the
respective surface region of the object at a right angle.
2o Known devices of the type mentioned at the outset, as
have previously been used in the wood and printing indus-
tries, are not suitable for W radiation as the Uv emit-
ters) was/were immovably arranged and the objects were
moved past the UV emitters) in a more or less fixed ori-
2s entation by the conveying system.
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Recently lacquers have moreover been developed which cure
under the effect of heat in an inert gas atmosphere to
form very hard surfaces. The heat can be supplied in a
wide variety of ways in this case, thus for instance by
s convection or infrared radiators. In the latter case,
similar problems to those described above for the use of
emitters occur. In particular, in other words, all sur-
face regions of the object to be lacquer coated are sup-
posedly moved past the infrared emitter at approximately
to the same spacing.
The object of the present invention is to configure a de-
vice of the type mentioned at the outset such that coat-
ings may also be cured on very uneven objects with a com-
plex shape, in particular vehicle bodies, so as to
15 achieve a good result.
This object is achieved according to the invention in
that the conveying system comprises a suspended carriage
which can be moved in a translatory manner along at least
one travel way and is suspended over the at least one
2o emitter, and in that two downwardly extending suspension
supports for suspension of the object are arranged one
behind the other in the longitudinal direction on a bogie
truck of the suspended carriage, the length of which sup-
ports can be changed independently of each other with the
25 aid of a motor.
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According to the invention, a conveying system with a
suspended carriage, as is already used per se for immer-
sion coating vehicle bodies or other objects, is used.
The present invention has found that an object may be
s pivoted using a suspended carriage about an axis that ex-
tends transversely to the travel way if the lengths of
the suspension supports are unevenly changed with the aid
of a motor, and, in particular, in opposite directions to
each other. Superimposing a pivoting movement of this
io type about a transverse axis with a translation of the
suspended carriage along the travel way, allows, for ex-
ample, the spacing between an emitter arranged below the
suspended carriage and a downwardly pointing surface of
the object to be kept substantially constant.
15 The suspended object is thus uniformly exposed to a quan-
tity of light and a light intensity as are required for
curing the material. Complete curing occurs only if, on
the one hand, the electromagnetic radiation strikes the
coating with an intensity that is above a threshold and,
20 on the other hand, this intensity is also maintained for
a specific period. In the event of insufficient inten-
sity, a polymerisation reaction does not occur or pro
ceeds only incompletely. Even with sufficient intensity
only incomplete curing is again attained with excessively
25 short radiation.
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A particularly advantageous embodiment of the invention
is characterised in that at least one of the suspension
supports comprises two belts or chains which can be indi-
vidually wound with the aid of a motor and which act on
s either side of the object at a supporting structure re-
ceiving the object. The supporting structure receiving
the object is thus suspended at three, or, if both sus-
pension supports are configured in this manner, four,
points of the suspended carriage bogie truck. As a result
io of individual changes in the length of the belts or
chains, the supporting structure and the objected fas-
tened thereto may also be pivoted about an axis extending
along the travel way in addition to about an axis extend-
ing transversely to the travel way. This in turn allows
i5 even lateral surfaces of the object to be oriented with
respect to the lateral emitters such that even in this
case all surface regions can be uniformly and completely
cured in the region in which the electromagnetic radia-
tion generated by these emitters acts.
2o It is also preferred if the conveying system comprises a
plurality of suspended carriages which each comprise a
separate driving unit for a translatory movement along
the travel way. The suspended carriages can thus convey
the objects independently of each other and move them
25 past the at least one emitter. The travel path can in the
process comprise, for example, one rail, two rails or
even a roller conveyor, as is known per se in connection
with conveying systems of this type in the prior art.
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An embodiment of the invention is particularly preferred
in which the device comprises a container that is open at
the top and arranged below the travel way, and into the
interior of which the object can be introduced with an
s extension of the length of the suspension supports, and
of which the interior can be subjected to electromagnetic
radiation from the at least one emitter. This container
ensures that no electromagnetic radiation and no gases
can escape in the lateral direction, which is to be
io avoided for the sake of the operators' health. In this
embodiment of the invention, the suspended carriages,
constructed for immersion and emergence of objects
in/from liquid containers, develop their advantages par-
ticularly well. Lowering into a container in particular
15 may be managed very easily with suspended carriages of
this type as even large differences in height may be eas-
ily bridged. The container can in this case be configured
as an independent component or as an appropriately lined
base region of a cabin housing or the like.
2o The arrangement of the emitters on or in the container
can vary:
It is thus possible that at least one emitter is fitted
in a wall or in the base of the container. With three-
dimensionally curved surfaces of objects to be treated,
25 the solution in which at least one emitter is fitted in
the opposing side walls extending parallel to the trans-
lational movement of the objects and in at least one of
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the two end walls extending perpendicular to the transla-
tional movement of the objects, as well as in the base of
the container, is preferred. In this case all sides or
surface regions of the object may be reached by electro-
s magnetic radiation without problem.
The most universally appropriate embodiment of the inven-
tion is obviously that in which a large number of emit-
tern is arranged on all walls and in the base of the con-
tamer.
to In the above embodiments, in which the emitters are ar-
ranged in the walls or in the base of the container, the
emitters form substantially large-area emitters.
However, emitters may also advantageously be used which
are configured as linear emitters. In this case an em
15 bodiment of the invention is particularly advantageous in
which a plurality of emitters is provided in a U-shaped
arrangement with two substantially vertical legs and a
substantially horizontal base. The object to be treated
is "threaded" as it were between the vertical legs of the
zo overhead frame.
The arrangement of the emitters on the substantially ver-
tical legs can be adapted to the course of the lateral
surfaces of the object. Thus even with curved lateral ob-
ject surfaces, uniform and complete curing of the coating
25 can be achieved on the lateral surfaces of the object.
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If the downwardly pointing surface of the object is very
curved it may be advantageous to adapt the arrangement of
emitters on the substantially horizontal base to the
course of the downwardly pointing surface of the object.
s A segment-like arrangement of the emitters on the hori-
zontal base allows the object to be moved past the ar-
rangement of emitters in such a way that the spacing
thereof from the downwardly pointing surface of the ob-
ject is largely constant.
io It is particularly preferred if a protective gas can be
supplied to the interior of the container. The protective
gas primarily has the function of preventing the presence
of oxygen in the radiation region of the emitters as oxy-
gen can be converted into harmful ozone, in particular
15 under the influence of UV light, and also affects the
course of the polymerisation reaction.
The protective gas should be heavier than air, as is the
case, for example, with carbon dioxide, so the protective
gas only escapes slowly from the container that is open
2o at the top. The container is thus filled with the heavy
protective gas similarly to with a liquid.
There is an inlet for the protective gas preferably in
the immediate vicinity of the at least one emitter. The
protective gas can thus simultaneously exercise a cooling
25 effect on the at least one emitter.
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It is also preferred if a moving reflector is associated
with at least one emitter on the side remote from the ob-
ject. Using this moving reflector the direction of the
electromagnetic radiation generated by the at least one
s emitter may be purposefully influenced. This allows the
available effective range of the electromagnetic radia-
tion to be enlarged.
The container can be provided with a reflective layer on
at least one inner surface. Lower power emitters may be
io used as a result.
The reflective effect is intensified in that the reflec-
tive layer is uneven. Under these circumstances the re-
flections take place at very different angles, so the in-
terior of the container is very uniformly filled with
i5 electromagnetic radiation with very varied directions of
propagation.
The layer may, for example, consist of an aluminium foil.
This has a very good reflective capacity for electromag-
netic radiation and is also very inexpensive. Unevenness
2o can be easily created by creasing the aluminium foil.
The device according to the invention should comprise a
cabin housing which prevents uncontrolled escape of gases
and electromagnetic radiation, in particular UV light.
Both of these would pose a health risk to operators.
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A sluice for the suspended carriage can be provided at
the inlet and outlet of the cabin housing respectively.
These sluices prevent relatively large quantities of air
from passing from the external atmosphere into the cabin
housing as the suspended carriage is driven into and out
of the cabin housing. The sluices also protect operators
from harmful electromagnetic radiation.
As permeation of air, in particular oxygen, into the in-
terior of the cabin housing is not completely eliminated
io with sluices either, however, an apparatus for removing
oxygen from the atmosphere inside the cabin housing is
expediently provided. This apparatus can include a cata-
lyst for catalytically binding the oxygen, a filter for
absorption or a filter for adsorption of oxygen.
If the coating material initially still contains rela-
tively large amounts of solvent, as is the case for exam-
ple with water-based lacquers, the device for removing
solvent from the material of the coating can comprise a
pre-heating zone.
2o If, on the other hand, powdery materials are to be proc-
essed, the device for initial gelling of this powdery ma-
terial can have a corresponding pre-heating zone.
In principle manual control of the suspended carriage is
possible if an operator can visually monitor the irradia-
tion process and controls the corresponding lifting and
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lowering movements as a function of the external contour
of the irradiated object.
However, the device preferably comprises a controller via
which the length of the suspension supports can be auto-
matically adapted to the vertical dimensions of the ob-
ject. This means that where the object is particularly
high, the length of the suspension supports is shortened,
so the spacing from an emitter arranged below the sus-
pended carriage is substantially constant. Where, on the
io other hand, the object is flatter, the length of the sus-
pension supports is increased, so the object is lowered
and brought closer to the emitter.
In an advantageous development of this embodiment the
length of the suspension supports can be changed by the
i5 controller in such a way that, during a conveying move-
ment of the object past the at least one emitter, the
quantity of electromagnetic radiation striking the mate-
rial per unit of area and the intensity thereof do not
fall below respectively predeterminable thresholds re-
2o quired for curing. This ensures that all downwardly
pointing surface regions of the object are exposed to the
same radiation intensity and substantially the same quan-
tity of radiation, i.e. the same irradiation in the
photometric sense.
2s It is also preferred in this configuration of the inven-
tion if the length of the suspension support can be
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changed by the controller such that, during a conveying
movement of the object past the at least one emitter, the
spacing in the vertical direction between the object and
the at least one emitter is at least approximately con
s stant. If this constant value is only just above the
threshold required for curing, more severe "overexposure"
which, for example, can lead to embrittlement or discol-
oration, is avoided.
It is also preferred in this connection if the controller
to comprises a memory for storing three-dimensional shape
data of the object. The controller can be provided with
this three-dimensional shape data, for example from a
higher-order data processing system.
As an alternative, or, for control reasons, in addition,
i5 to this the device can comprise a measuring station up-
stream - optionally also directly upstream - of the at
least one emitter in the conveying direction, by means of
which station the three-dimensional shape data of the ob-
ject can be detected. This data can subsequently be used
2o for movement guidance of the object upstream of the emit-
ter (s) .
In a particularly simple embodiment the measuring station
merely comprises one or more light barriers) which
is/are preferably arranged in the immediate vicinity of
2s the at least one emitter and cooperates) with the con-
troller. If the object to be irradiated interrupts a
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light barrier, a corresponding deflection of the object
is brought about in real time.
More accurate detection of the three-dimensional shape is
possible if the measuring station comprises an optical
sampler which, for example, can contain an infrared light
source, by which the object can be sampled in a scanner-
like manner in at least one direction.
A further possibility of precisely detecting the three-
dimensional shape is provided by digital image processing
io and recognition of video images of the object. The meas-
uring station thus comprises a video camera and an appa-
ratus for digital image recognition.
At the output side the device can comprise a post-heating
zone to complete curing.
i5 In the case of objects with cavities it may be expedient
to arrange a further inlet for protective gas within the
input-side sluice in such a way that the cavities are
flushed with protective gas, so air contained therein is
displaced.
zo The electromagnetic radiation is preferably UV light or
infrared radiation.
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Further features and advantages of the invention emerge
from the following description of the embodiments with
reference to the drawings, in which:
Fig. 1 shows a curing device for curing W lacquers in a
highly simplified longitudinal section that is not to
scale;
Fig. 2 shows an enlarged view of a portion of the curing
device shown in Fig. 1;
Fig. 3 shows a cross-section along the line III-III
io through a portion of the device shown in Fig. 1;
Fig. 4 shows a further embodiment for a curing device in
a view corresponding to Fig. 2.; and
Fig. 5 shows the embodiment of Fig. 4 in a view corre-
sponding to Fig. 3.
Fig. 1 shows a device for curing UV lacquers in a highly
simplified longitudinal section that is not to scale, the
device being designated as a whole by 10. The curing de-
vice 10 illustrated by way of example is part of a lac-
quer coating unit which is provided for applying multi-
layer lacquer coatings to preassembled car bodies 12.
The curing device 10 comprises an overhead conveying sys-
tem, which is known per se, for the vehicle bodies 12 and
comprises an overhead rail 14 and suspended carriages 16
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hung thereon. Using this overhead conveying system the
vehicle bodies 12 are supplied to the curing device 10
and conveyed through the individual stations thereof.
These stations are a pre-heating zone 18, an irradiation
device 20 and a post-heating zone 22.
The pre-heating zone 18 and the post-heating zone 22 con-
tain heating devices, indicated by 24 and 26 respectively
and configured as hot air heaters. Alternatively, heating
by means of IR emitters or with the aid of a magnetron
to for generating microwaves may also be considered. The
pre-heating zone 18 can perform different functions, de-
pending on the type of coating material. If this material
is solvent based, for example a water-based paint, the
solvents are largely removed in this case. If powdery ma-
terial is involved, the pre-heating zone 18 is used to
initially gel the powder and to thus make it ready for
polymerisation.
The irradiation device 20 comprises a cabin housing 28
which is constructed such that neither gas exchange with
2o the environment nor escape of UV light is possible. To be
able to observe the processes in the interior 30 of the
cabin housing 28 from the outside, windows 32 are let
into the side walls of the cabin housing 28, which are
permeable to visible light but impermeable to UV light.
To prevent exchange of gases with the environment, the
irradiation device 20 comprises an inlet sluice 34 and an
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outlet sluice 36 which the suspended carriages 16, with
the vehicle bodies fastened thereto, have to pass when
driving into and out of the interior 30. The inlet
sluice 34 and the outlet sluice 36 are in each case con-
structed in the illustrated embodiment as double sluices
with two moving rollup doors 341, 342 and 361, 362. Owing
to the overhead rail 14 the rollup doors 341, 342 and
361, 362 are rolled up from the bottom to keep a passage
slot for the rail 14 as short as possible.
io A trough-like container 38, which can be filled with a
protective gas that is stored in a gas holder 40 and can
be introduced via a line 42 ending in the base of the
container 38, is arranged in the interior 30 of the cabin
housing 28. In the illustrated embodiment the protective
i5 gas is carbon dioxide as in the gaseous state this is
heavier than air and thus behaves similarly to a liquid
in the container 38 that is open at the top. The quantity
of protective gas supplied via the line 42 is in dynamic
equilibrium with the quantity of protective gas that es-
2o capes inter alia via the inlet and outlet sluices 34 and
36 respectively.
The substantially cuboidal container 38 comprises at its
base surface 44, its side walls 39 extending parallel to
the conveying direction, designated by 46, of the convey-
25 ing system and also at its end walls 41 perpendicular
hereto a large number of UV emitters 48 which direct UV
light into the interior of the container 38. For the
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sake of clarity the UV emitters which are arranged on the
side wall 39 visible to the observer, are shown only in
part. The light exit faces of the W emitters 48 are cov-
ered by an IR filter, so the heat radiation generated by
s the UV emitters 48 can only pass into the interior of the
container 38 to a small extent.
Instead of a central line 42 for introducing protective
gas, a large number of lines may also be provided which
end right next to the W emitters 48 on the walls of the
io container 38. The protective gas flushes the portions of
the UV emitters 48 which become hot during operation.
Protective gas may also be purposefully directed toward
vehicle bodies 12 immersed therein in the container to
displace undesirable oxygen-containing residual gases
i5 which under the influence of UV light can lead to the
formation of ozone and affect the polymerisation reac-
tion.
The interior 30 is connected to a regeneration circuit 42
that has the function of removing oxygen, which is intro-
2o duced into the interior 30 by the vehicle bodies 12 or
penetrates when the inlet sluice 34 or outlet sluice
36 is opened, from the atmosphere prevailing in the inte-
rior 30. For this purpose, gas is continuously removed
from the interior 30 via a line 43 and conveyed, for ex-
25 ample via a catalyst 45 which catalytically binds the
oxygen. A portion of this gas is returned to the interior
30 of the cabin housing 28 via a line 47 while a further
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portion is discharged into the external atmosphere via a
line 49.
Details of the overhead conveying system and container 38
will be described hereinafter with reference to Fig. 2
s and 3 which show a detail of the interior 30 of the cabin
housing 28 in an enlarged longitudinal section and cross-
section respectively.
Fig. 2 shows that the rail 14 of the overhead conveying
system is fastened via anchors 16 to an overhead struc-
to ture (not shown). The suspended carriage 16 comprises a
bogie truck 50 which for its part consists of a platform
52 and running gear groups 54a, 54b fastened thereto and
extending upwards. The running gear groups 54a, 54b,
which can be seen particularly clearly in the cross-
15 sectional view of Fig. 3, each contain a running wheel 56
which can roll from the top on a horizontal leg 57 of the
rail 14 which is substantially C-shaped in cross-section.
The running wheel 56 can be driven by a drive unit 58 in
the form of an electric motor. Undesirable tilting of the
2o suspended carriage 16 about a longitudinal axis is pre-
vented by guide rollers 60 which enclose a shoulder 62
formed on the lower leg 57 of the rail 14. An accumulator
64 is provided on the platform 52 of the bogie truck 50
for supplying power to the drive unit 58. Alternatively,
25 the power can also be supplied via contact rails let into
the rail 14.
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A respective pair of suspension supports hangs from the
front and back of the platform 52 in the longitudinal di-
rection, of which only the suspension supports 66a, 66b
facing the observer can be seen in Fig. 2. Fig. 3 shows a
further suspension support 66c. Each suspension sup-
port 66 comprises a roller 68 driven by means of a motor,
and a belt 70, which can be wound thereon and is made of
a UV-resistant material, and a fastening bracket 72
provided thereon. The fastening bracket 72 engages be-
to neath a supporting structure 74 to which the vehicle body
is fastened. This supporting structure 74 can, for exam-
ple, be what is referred to as a skid carrier which is
used for conveying vehicle bodies 12 on roller conveyors.
In the figures the supporting structure 74 is shown
i5 slightly distanced from the fastening brackets 72 to make
it clear that the connection between the fastening
bracket 72 and the supporting structure 74 can be easily
broken.
As a result of this suspension of the supporting struc-
2o ture 74 at the four corner points with the aid of the
fastening brackets 72, the vehicle body 12 can be moved
aloft in the direction indicated by the arrow 76 but also
in the longitudinal direction of the vehicle body 12 and
pivoted in the transverse direction thereof. For this
25 purpose, it is only necessary to drive the drive units
for the rollers 68 in different ways in order to thus in-
dividually change the length of the belts 70.
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The W emitters 48 let into the base face 44, the side
walls 39 and the end walls 41 of the container 38 can be
seen in the container 38 that is visible below the vehi-
cle body 12. The W emitters 48, which are shown two-
dimensionally, can, for example, contain one or more tu-
bular lighting means or a large number of approximately
punctiform light sources. All inner surfaces of the con-
tamer 38, where they are not occupied by exit faces of
the UV emitters 48, are covered by a reflective aluminium
io foil 78 which has also been made uneven, for example by
creasing or by other irregular elevations.
The above-described curing device 10 operates as follows:
During operation the W emitters 48 are functioning so
the entire interior of the container 38 is flooded with
i5 W light which is additionally reflected by the creased
aluminium foil 78, provided on the inner surfaces of the
container 38, in a large number of different directions
and is thus evened out. The UV emitters 48 are cooled by
the gaseous carbon dioxide supplied via the line 42. The
2o thus only insubstantially pre-heated carbon dioxide gas
enters the container 38 and fills it from the bottom up.
The carbon dioxide issuing from the top of the con-
tamer 38 and which can be mixed to a small extent with
gas emissions from the lacquer curing on the vehicle body
25 12 as well as ozone, passes into the interior 30 of the
cabin housing 28 and from there is removed by suction via
the outlet 43. Removal by suction can also take place di-
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rectly at the upper edge of the walls of the container
38.
It is assumed that a plurality of lacquer layers have al-
ready been applied in an upstream coating direction of
the lacquer coating plant. The upper lacquer layer is a
clear lacquer which is applied as a powder to the lacquer
layers that already exist. The clear lacquer polymerises
under the effect of UV light and thus cures. A prerequi-
site for this is that the powdery lacquer is converted in
to advance into a more or less liquid, gel-like state. The
pre-heating zone 18 is used for this purpose, in which a
vehicle body 12 provided therein is heated to a tempera-
ture of about 90 °C. At this softening temperature the
powder is transformed into said gel-like state.
From the pre-heating zone 18 the suspended carriage 16,
with vehicle body 12 hung therefrom, is fed to the inlet
sluice 34. By successively opening and closing the rollup
doors 341, 342 of the inlet sluice 34 the suspended car-
riage 16 with the vehicle body 12 is introduced into the
2o interior 30 of the cabin housing 28 without relatively
large quantities of the protective gas contained therein
being able to penetrate to the outside.
As soon as the suspended carriage 16 with the vehicle
body 12 suspended thereon has reached the position above
the container 38, shown in Fig. 2 or 3, the vehicle
body 12 is lowered into the container 38 by unwinding the
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belts 70 from the rollers 68. The now gel-like clear lac-
quer is accordingly actually cured under the effect of
the W light generated by the W emitters 48. As the pro-
tective gas displaces the air originally present in the
s interior 30, W light is prevented from converting the
molecular atmospheric oxygen into ozone, which would af-
fect the polymerisation reaction.
So the front hood 80 and the tailgate 82 of the vehicle
body 12 in particular also receive the quantity of UV
to light required for curing (the quantity of light or dose
of light is designated in photometry as irradiation with
the unit Ws/m2 or J/cm2), the vehicle body 12 immersed in
the container 38 is pivoted about a transverse axis 83
(see Fig. 3) of the vehicle body 12 such that the front
15 hood 80 and then the tailgate 82 are also positioned suf-
ficiently close to the UV emitters 48 let into the base
face 44 of the container 38. For this purpose, the drive
units for the rollers 68 can, for example, be driven in
such a way that the leading and trailing pairs of belts
20 70 are shortened or lengthened in opposite directions.
As the lateral surfaces of the vehicle body 12 are also
highly curved, as can be seen in particular in the cross-
sectional view of Fig. 3, the pair of belts 70 arranged
on both longitudinal sides of the vehicle body 12 can be
25 changed in length such that the vehicle body 12 performs
a pivoting movement about its longitudinal axis 85 (see
Fig. 2). All regions of the lateral surfaces of the vehi-
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cle body 12 may thus be brought sufficiently close to the
UV emitters 48 let into the side walls 39 of the con-
tamer 38.
After the curing process in the container 38 has fin-
s fished, the vehicle body 12 is raised again by shortening
the belts 70 evenly. The suspended carriage 16 with the
vehicle body 12 is subsequently supplied via the outlet
sluice 36 to the post-heating zone 22 in which a tempera-
ture of 105 °C prevails. The vehicle body 12 stays there
to for approximately five to ten minutes, during which the
polymerisation reaction is completely concluded. The time
and temperature can vary in this case depending on the
coating material.
For controlling these processes there is provided a cen-
i5 tral controller which is indicated in Fig. 1 by 90. Via a
bus system the controller 90 controls the individual ser-
vomotors within the curing device 10 and in particular
the suspended carriage 16. As controllers of this type
for suspended carriages are known in terms of principle
2o in the prior art, an illustration of the details of the
bus system, etc. will be dispensed with.
In the controller 90 three-dimensional shape data of the
vehicle body 12 is stored in a memory 92, the data being
required to pivot the vehicle body 12 in the container 38
2s in the above-described manner along the longitudinal
axis 85 and the transverse axis 83. This three-
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dimensional shape data can, for example, be retrieved
from a higher-order data processing system in which data
relevant to all vehicle bodies 12 passing through the
curing device 10, such as type and colour of the lacquer
s coating and body type and shape, is stored. All that is
then required is a reader which recognises the type of
vehicle body 12 entering the irradiation device 20, so
the three-dimensional shape data associated with this
type can be retrieved.
to Alternatively, or, for control purposes, additionally it
is also possible to ascertain the requisite three-
dimensional shape data using a measuring device 94 which
is arranged inside the inlet sluice 34 (see Fig. 1). The
measuring device 94 has a U-shaped frame to which a large
15 number of optical samplers 96 with infrared light sources
are fastened in the vertical direction and transversely
to the conveying direction 46. The optical samplers 96
detect in a scanner-like manner the external contour of
the vehicle body 12 as it passes through the measuring
2o device 94.
The measuring device can alternatively or, as shown in
Fig. 1, additionally comprise a video camera 97 with an
image recognition device 99 associated therewith. The
video camera 79 produces a digital image of the vehicle
2s body 12 from which the three-dimensional shape of the ve-
hicle body is derived in the image recognition device by
algorithms known per se.
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Fig. 4 and 5 show an alternative embodiment for the con-
tainer 38 and the UV emitters 48 arranged therein in
views derived from Fig. 2 and 3. The alternative embodi-
ment differs from that described above merely in that UV
s emitters 48 are not distributed over the entire inner
surface of the container 38, as is the case with the em-
bodiment shown in Fig. 1 to 3. Instead, a U-shaped ar-
rangement of a total of six linear UV emitters 48', which
are articulated to each other in pairs and can be adapted
to to the cross-section of the vehicle body 12 by way of hy-
draulic adjusting elements 100, are located in this case
in a container 38' that is extended in the longitudinal
direction.
In this embodiment the vehicle body 12 is initially also
15 let into the container 38' in the vertical direction. The
suspended carriage 16 in the conveying direction 46 is
subsequently slowly set in motion in the conveying direc-
tion 46, so the vehicle body 12 suspended on the sus-
pended carriage 16 is passed between the arrangement of
2o the UV emitters 48'. If the cross-sectional contour of
the vehicle body 12 changes significantly in it longitu-
dinal direction, the UV emitters 48' can be adjusted ac-
cordingly by actuating the adjusting elements 100.
As an alternative or in addition to this type of compen-
25 ration there is, however, also the possibility in this
case of also optimally positioning the lateral surfaces
of the vehicle body 12 with respect to the UV emitters
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48' as a result of the above-described pivoting movements
of the vehicle body 12 around the longitudinal axis 85.
The W light generated by the W emitters 48' can subse-
quently strike the relevant surface region substantially
s at a right angle.
If needed, the translational movement of the suspended
carriage 16 may also be interrupted or reversed, so indi-
vidual surface regions on the vehicle body 12 are irradi-
ated for longer than others.
io In the embodiment shown in Fig. 4 and 5, the measuring
station 96 can also be arranged directly upstream of the
W emitters 48' in the conveying direction 46. If the
measuring station 96 comprises, for instance, one or more
light barriers in this case, a corresponding deflection
15 of the vehicle body 12 can be brought about in real time
by changing the length of the belts 70 when the vehicle
body 12 arrives in the detection range of a light bar-
rier.
The above embodiments are used for curing lacquers under
2o W light. However, they may also be used with lacquers
which cure under the effect of heat, in particular in an
inert gas atmosphere, in other words in a COZ or nitrogen
atmosphere for example. In this case substantially only
the W emitters described need to be replaced by IR emit-
25 tern. Other constructional adjustments connected with the
change in electromagnetic radiation are known to a person
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skilled in the art and do not need to be described in
more detail here.
