EP1649229B1 - Device for hardening the coating of an object, consisting of a material that hardens under electromagnetic radiation, more particularly an uv paint or a thermally hardening paint - Google Patents

Abstract

The invention relates to a device for hardening a coating of an object, more particularly a car body (12), said coating consisting of UV paint, a thermally hardening paint or the like. The device comprises at least one radiator (58, 60a, 60b, 62a, 62b) producing electromagnetic radiation. A conveyor system (14, 16, 46) that moves the object (12) to the proximity of the radiator (58, 60a, 60b, 62a, 62b) and moves it away from said radiator is also provided. The conveyor system (14, 16) comprises a lifting car (46; 461) with a running gear (50) having a lift platform (54) for receiving the object (12), whose height relative to the running gear (50) can be adjusted by means of a motor. The at least one radiator (58, 60a, 60b, 62a, 62b) is arranged in such a manner that the lifting car (46; 461) and the object (12) located thereon can be guided through under the at least one radiator (58, 60a, 60b, 62a, 62b), wherein the vertical position of the object (12) can be changed.

Description

1. a) mindestens einem elektromagnetische Strahlung erzeugenden Strahler;
2. b) einem Fördersystem, welches den Gegenstand in die Nähe des Strahlers und von diesem wieder wegführt.

The invention relates to a device for curing a made of a material which cures under electromagnetic radiation, in particular from a UV varnish or from a thermosetting varnish, existing coating of an article, in particular a vehicle body, with

1. a) at least one emitter generating electromagnetic radiation;
2. b) a conveyor system, which leads the object in the vicinity of the radiator and from this again.

Under UV light-curing paints have been used mainly for painting sensitive objects, such as wood or plastic. There is especially the advantage of these paints to fruition that they can be polymerized at very low temperatures. As a result, the material of the objects is preserved from decomposition or outgassing. The curing of coating materials under UV light, however, has other advantages, which this coating process now interesting for use in other areas. This is in particular the short curing time, which is reflected directly in a shortening of the system length especially in those coating processes that operate in a continuous flow. This is associated with huge cost savings. At the same time, the device with which the gases to be introduced into the interior of the device are conditioned can be reduced, which also contributes to cost savings. Finally, the low operating temperature is also advantageous for such objects, which could in themselves tolerate higher curing temperatures, for reasons of saving energy, in particular thermal energy.

Many of the items one would like to coat with UV-curable materials, e.g. Vehicle bodies, have a highly uneven, often three-dimensionally curved surface, so that it is difficult to bring these objects in the radiation range of a UV lamp so that all surface areas have approximately the same distance from the UV lamp and the UV radiation at about impinges at a right angle to the respective surface area of the article.

Known devices of the type mentioned, as previously used in the wood and plastics industry, are unsuitable for this purpose, since here or the UV lamps were immobile and the objects have been guided by the conveyor system in a more or less fixed orientation on the UV lamps or the UV lamps (see, for example US 5075132 ).

In addition, coatings have recently been developed which cure on exposure to heat in an inert gas atmosphere to form very hard surfaces. The heat can be supplied in different ways, such as by convection or by infrared emitters. In the latter case, similar problems arise as described above for the use of UV lamps. In particular, therefore, all surface areas of the object to be painted should be guided past the infrared radiator at approximately the same distance.

Object of the present invention is to provide a device of the type mentioned in such a way that even coatings on complicated shaped, very uneven objects, in particular vehicle bodies, can be cured with good results.

This object is achieved in that the conveyor system comprises a truck with a chassis, which has a height adjustable motor relative to the chassis lifting platform for receiving the object, and that the at least one radiator is arranged so that the truck with the recorded object can be passed under the at least one radiator.

The invention is based on the finding that can be superimposed with such a height-adjustable lifting platform having lift truck in a very simple manner, a movement in the vertical direction with a translational movement in the horizontal direction. This makes it possible to pass the article on the truck under the at least one emitter and thereby to change the height of the lifting platform so that the object applied to it is exposed uniformly to all surface areas of a radiation amount and a radiation intensity, as they are required for curing of the material , In fact, complete curing only occurs when the electromagnetic radiation hits the coating on the one hand above a threshold intensity and, on the other hand, this intensity is maintained over a certain period of time. If the intensity is too low, a polymerization reaction does not start or is incomplete; if irradiation is too short, only incomplete curing will be achieved, even if the intensity is sufficient.

Even more versatile is such a truck when, according to a particularly preferred embodiment of the invention, the lifting platform relative to the chassis is tilted by a motor. The tilt can be about one Transverse axis of the lift truck, a longitudinal axis of the lift truck or superimposed on both said axes done.

A Verkippbarkeit about a transverse axis makes it possible to dispense with a translational movement in the horizontal direction if necessary., Since now the object can still be oriented in many cases with respect to several arranged in a plane radiator or a large area radiator so that recessed areas of the upward facing surface of the article are still sufficiently exposed to electromagnetic radiation.

A Verkippbarkeit about a longitudinal axis of the lift truck is particularly advantageous if lateral radiators are provided and the article also has on its side surfaces a curved or otherwise highly uneven contour.

Can be realized tiltability about a tilt axis, for example, characterized in that the lifting platform comprises two support plates, which are separated by at least one variable-length punch. This stamp may be, for example, hydraulically actuated telescopic cylinder. Tilting about two tilt axes requires at least two punches.

Particularly preferred is also an embodiment of the invention in which the device comprises a container having an opening through which the article is inserted by height adjustment of the lifting platform in the container, wherein the interior of the container can be acted upon by at least one radiator with electromagnetic radiation. This container ensures that in the lateral direction no electromagnetic radiation and no gases can escape, which is to avoid health reasons for the operator. The container may be formed as an independent part, as a channel or as a suitably lined floor or roof area of a cabin housing o. Ä.

• So ist es möglich, daß mindestens ein Strahler in eine Wand, eine Decke oder in einen Boden des Behälters eingebaut ist. Bei dreidimensional gekrümmten Oberflächen von zu behandelnden Gegenständen wird dabei diejenige Lösung bevorzugt, bei welcher in den gegenüberliegenden, parallel zur Translationsbewegung der Gegenstände verlaufenden Seitenwänden und in mindestens einer der beiden senkrecht zur Translationsbewegung der Gegenstände verlaufenden Stirnwände sowie in eine Decke oder einem Boden des Behälters mindestens ein Strahler eingebaut ist. Dann lassen sich alle Seiten bzw. Oberflächenbereiche des Gegenstandes von elektromagnetischer Strahlung problemlos erreichen.

The arrangement of the emitters on or in the container can be different:

• So it is possible that at least one spotlight is installed in a wall, a ceiling or in the bottom of the container. In the case of three-dimensionally curved surfaces of objects to be treated, that solution is preferred in which at least in the opposite, parallel to the translational movement of the articles extending side walls and in at least one of the two perpendicular to the translational movement of the objects end walls and in a ceiling or a bottom of the container a spotlight is installed. Then all sides or surface areas of the object can be easily reached by electromagnetic radiation.

Of course, the most universal use is that embodiment of the invention in which a plurality of radiators is arranged on all walls and in a ceiling or a bottom of the container.

In the above embodiments in which the radiators are arranged in the walls or in a ceiling of the container, the radiators substantially form surface radiators.

However, it can also be used advantageously radiator, which are designed as linear emitters. In this case, in particular an embodiment of the invention is advantageous in which a plurality of radiators are arranged on a bridge-like portal frame, which has two substantially vertical legs and a substantially horizontal base. The object to be treated is "threaded through" between the vertical legs of the portal frame, as it were.

The arrangement of the radiators on the substantially vertical legs of the portal frame can be adapted to the course of the side surfaces of the article. Thus, a uniform and complete curing of the coating on the side surfaces of the object can be achieved even with a curved side contour of the article.

If the downwardly facing surface of the article is highly curved, it may be advantageous to have the assembly the radiator on the substantially horizontal base to adapt to the profile of the downwardly facing surface of the object. Such a segmental arrangement of the radiators on the horizontal base makes it possible to bring the object past the arrangement of the radiator, that their distance from the downwardly facing surface of the object remains substantially constant.

It is particularly preferred if a protective gas can be supplied to the interior of the container. The shielding gas has primarily the function of preventing the presence of oxygen in the radiation area of the radiators, since oxygen can be converted into harmful ozone, in particular under the influence of UV light, and also impairs the course of the polymerization reaction.

In a container having an upward or side facing opening for insertion of the article, it is particularly favorable when the inert gas is heavier than air. This can be considered, for example, carbon dioxide.

In a container having a downwardly facing opening for insertion of the article, it is particularly advantageous if the protective gas is lighter than air. For example, helium is used for this purpose.

If an inlet for the protective gas is in the immediate vicinity of the at least one radiator, then this can be used at the same time as a cooling gas for the radiator. Alternatively or in addition to this, however, at least one inlet can also be aligned so that the protective gas emerging from the inlet is directed directly onto the surface currently being irradiated. In this way, it is ensured that the proportion of undesirable foreign gases is very low at the reaction site where the electromagnetic radiation causes the curing.

If at least one radiator is assigned a movable reflector on the side facing away from the object, an additional adaptation of the radiation direction to the course of the surface of the object to be treated is possible.

The container may be at least partially lined with a reflective layer. As a result, emitters with lower power can be used.

It is particularly favorable if the layer is uneven. The reflections take place at different angles under these circumstances, so that the interior of the container is filled very uniformly with electromagnetic radiation of different propagation directions.

As a layer material, for example, is an aluminum foil into consideration, since this has a very good reflectivity for electromagnetic radiation and is also inexpensive. In addition, an uneven layer can thus be realized in a simple manner, namely by crumpling the aluminum foil.

The device according to the invention should have a cabin housing which prevents an uncontrolled escape of gases and electromagnetic radiation. Both would be hazardous to health for the operating personnel.

At the inlet and the outlet of the cabin housing a lock for the truck can be provided in each case. These locks prevent that when entering and extending the trolley into or out of the cabin housing larger amounts of air from the outside atmosphere get into the cabin housing. In addition, the locks protect operators from hazardous electromagnetic radiation.

In the case of objects with cavities, it may also be expedient to arrange a further inlet for protective gas within the inlet-side lock such that the cavities are flushed with protective gas, whereby air contained therein is displaced.

However, since even with locks the ingress of air, especially of oxygen, in the interior of the Cabin housing can not be completely suppressed, a device for removing oxygen from the inside of the cabin housing atmosphere is expediently provided. This device may comprise a catalyst for the catalytic binding of the oxygen, a filter for absorption or else a filter for the adsorption of oxygen.

If the coating material initially still contains a relatively large amount of solvent, as is the case, for example, with water-based paints, the device for removing the solvent from the material of the coating may have a preheating zone. On the other hand, when powdery materials are to be processed, the device for setting this powdered material may have a corresponding preheating zone.

Furthermore, it can be provided that the device for completing the curing has a reheating zone. The initiated by the electromagnetic radiation curing reaction can continue to run in the reheating zone until the coating is completely cured.

In principle, manual control of the lift truck is also possible if an operator can visually monitor the irradiation process and controls the corresponding lifting and, if necessary, tilting movements of the lifting platform as a function of the outer contour of the irradiated object. Preferably, however, the device has a controller on, which controls the height of the lifting platform automatically in response to the upward-facing outer contour of the object.

The height of the lifting platform can be changed by the controller such that during a translational movement of the object past the at least one radiator, the distance in the vertical direction between the object and the at least one radiator remains at least approximately constant. In this way, it is ensured that all upwardly facing surface areas of the object of the same radiation intensity and in about the same amount of radiation, d. H. the same irradiation in a photometric sense.

The spatial form data of the object required for such a control can be provided by a higher-level data processing system. However, the device can also detect this spatial shape data itself. For this purpose, provision is made for a measuring station arranged upstream of the at least one emitter in the conveying direction, by means of which the spatial form data of the object can be detected.

In a particularly simple embodiment, the measuring station comprises only one or more light barriers, which are preferably arranged in the immediate vicinity of the at least one radiator and interact with the controller. Interrupts the object to be irradiated a light barrier, so a corresponding evasive movement of the object is caused in real time.

A more accurate detection of the spatial form is possible if the measuring station has at least one optical scanner, which may contain, for example, an infrared light source through which the object can be scanned scanner-like in at least one direction. Another way to accurately capture the spatial shape is through digital image processing and recognition of video images of the subject. The measuring station then has a video camera and a device for digital image recognition.

In particular, in the embodiments in which the article is passed on the pallet truck under a gantry, the truck must also perform a translational movement. Since the coating on the object must not be exposed too short of the electromagnetic radiation, this translational movement can not be performed arbitrarily fast. If a pallet truck is slowly guided through the gantry and, after transfer of the item to a conveyor system, subsequently returned empty to its starting point, this process takes a not inconsiderable amount of time.

It is therefore advantageous if the conveyor system comprises exactly one pallet truck and a carriageway for the truck, along which arranged the at least one radiator with a receiving station for receiving the object on the lifting platform and a dispensing station for dispensing the object spatially coincide. Such an arrangement causes the truck with the object applied thereto twice, namely once in the forward and once in the reverse direction, past the at least one radiator and thereby returns to its starting point. There, the object can be removed from the lifting platform, which is then free for receiving a new object to be irradiated. The travel speed past the at least one emitter can be approximately doubled in this embodiment of the invention, since all surface regions are exposed twice to the electromagnetic radiation. This embodiment of the invention requires comparatively few plant components.

A higher throughput can be achieved when the conveyor system comprises at least two pallet trucks, extending between a receiving station for receiving the object on the lifting platform and a dispensing station for dispensing the article two lanes for the truck so that the trucks between the receiving station and the Dispensing station can circulate in a closed circuit.

The electromagnetic radiation is preferably UV light or infrared radiation.

Figur 1

eine Vorrichtung zur Aushärtung von UV-Lacken in einem stark vereinfachten und nicht maßstäb- lichen Längsschnitt;

Figur 2

eine Vorderansicht eines Portalgerüsts mit ei- nem hindurchfahrenden Hubwagen, der eine Kraft- fahrzeugkarosserie trägt;

Figuren 3a bis 3c

einen Ausschnitt aus der Figur 1 für unterschiedliche Phasen während des Durchfah- rens des Hubwagens durch das Portalgerüst;

Figur 4

ein Hubwagen, bei dem sich eine darauf auf ge- setzte Fahrzeugkarosserie in einer Querrichtung verkippen läßt;

Figur 5

eine der Figur 2 entsprechende Darstellung, bei der eine von dem Hubwagen getragene Fahrzeugka- rosserie um eine Längsachse verkippt ist;

Figuren 6a und 6b

stark vereinfachte Draufsichten auf ei- nen Innenraum eines Kabinengehäuses gemäß einem anderen Ausführungsbeispiel zu zwei unter- schiedlichen Zeitpunkten.

Further features and advantages of the invention will become apparent from the following description of the embodiments with reference to the drawing. Show:

FIG. 1

a device for curing UV lacquers in a highly simplified and not to scale longitudinal section;

FIG. 2

a front view of a gantry with a driving truck, which carries a motor vehicle body;

FIGS. 3a to 3c

a section of the FIG. 1 for different phases during the passage of the lift truck through the gantry;

FIG. 4

a pallet truck in which a vehicle body placed thereon can be tilted in a transverse direction;

FIG. 5

one of the FIG. 2 corresponding representation in which a vehicle body supported by the pallet truck is tilted about a longitudinal axis;

Figures 6a and 6b

greatly simplified plan views of an interior of a cabin housing according to another embodiment at two different times.

In the FIG. 1 a device for curing UV varnishes is shown in a highly simplified and not to scale longitudinal section and indicated generally at 10. The exemplified curing device 10 is part of a painting, which is intended to apply a multi-layer paint on pre-assembled vehicle bodies 12.

The curing device 10 comprises a per se known roller conveyor system for the vehicle bodies 12, which comprises a roller conveyor 14, which is divided by an opening 15 to be described in two sub-segments 14 a and 14 b, and resting thereon carrier 16 for the motor vehicle bodies 12. Such carriers, also referred to as skid carriers, have runner-like sliders with which they rest on the roller conveyor 14. Since such a roller conveyor system is known per se in the prior art, the presentation of further details is omitted.

With the help of the beyond the curing device 10 extending roller conveyor system, the vehicle bodies 12 of the curing device 10 can be supplied and transported between the individual stations of the curing device 10. These stations are a preheating zone 18, an irradiation device 20 and a reheating zone 22.

The preheating zone 18 and the reheating zone 22 each include 24 and 26 indicated and designed as hot air heaters heaters. Alternatively, heating by IR emitters or by means of a magnetron is suitable for generating microwaves. The preheating zone 18 may perform different functions depending on the type of coating material. If this material is a solvent-based material, for example a water-based paint, the solvents are removed as far as possible. If it is a powder material, then the preheating zone 18 serves to anneal the powder and in this way to make ready for the polymerization.

The irradiation device 20 comprises a cabin housing 28, which is designed so that neither a gas exchange with the environment nor leakage of UV light is possible. In order to be able to observe the processes in an interior 30 of the cabin housing 28 from the outside, 28 windows 32 are embedded on the outer walls of the cabin housing, which are permeable to visible light, but impermeable to UV light.

In order to prevent an exchange of gases with the environment and to protect the operator from UV light, the irradiation device 20 further comprises an inlet lock 34 and an outlet lock 36, the carrier 16 with the vehicle bodies 12 mounted thereon when entering the interior 30th as well as when driving out must happen from this. The inlet lock 34 and the outlet lock 36 are each formed in the illustrated embodiment as double locks with two movable roller doors 341, 342 and 361, 362.

In the interior 30 of the cabin housing 28, a ceiling 37 is retracted such that the underlying part of the inner space 30 forms a kind of container 38. The blanket 37 contains the above-mentioned opening 15, over which the roller conveyor 14 is interrupted. As an alternative to this embodiment, it can also be provided that the ceiling 37 is dispensed with and instead a separate container designed as a trough is placed in the then free inner space 30, over which part of a roller conveyor 14 extends.

The container 38 is, regardless of the nature of its execution, filled with a protective gas which is stored in a gas tank 40 and via a line 42 opening into the bottom of the container 42 can be introduced. In the illustrated embodiment, the shielding gas is carbon dioxide, since it is heavier than air in the gaseous state and thus fills the upwardly open container 38 much like a liquid. The amount of the protective gas supplied via the line 42 is in dynamic equilibrium with the amount of protective gas which escapes inter alia via the inlet and outlet locks 34 and 36.

Furthermore, the inner space 30 is connected to a regeneration circuit 42, which has the task of oxygen, which is introduced via the vehicle bodies 12 into the inner space 30 or when opening the inlet lock 34 or the outlet lock 36, from the prevailing in the inner space 30 atmosphere remove. For this purpose, the interior 30 is continuously withdrawn via a line 43 gas and passed, for example via a catalyst 39, which catalytically binds the oxygen. A portion of this gas is returned via line 47 back into the interior 30 of the cabin housing 28, while another part is discharged via a line 51 into the outside atmosphere.

On a bottom surface 45 of the container 38 a generally designated 46 pallet truck is placed and translationally movable in a direction indicated by a double arrow 48 direction, including a arranged on the truck 46 and in the FIG. 1 not shown drive serves. The lift truck 46 has a chassis 50 and a lifting device 52, as it is known per se in the prior art and can be performed, for example, as a hydraulically or electrically driven scissors drive. The upwardly facing plane of the lifting device 52, which serves to receive carriers 16, forms a lifting platform 54. In the case of a lifting device 52 designed as a shear drive, this lifting platform 54 can also consist of a frame connecting the scissor legs movably; The term "platform" does not have to be inevitably imply a continuous surface. With the help of the lifting device 52, the lifting platform 54 can be moved vertically in the direction indicated by a double arrow 49 direction.

In the container 38, a portal frame 44 is further arranged, the details of which below with reference to the FIG. 2 be explained.

In the FIG. 2 the portal frame 44 is shown in a front view in an enlarged view. The gantry 44 spans bridge-like a provided for the travel of the lift truck 46 56 on the bottom surface 45 of the interior 30. At the portal frame 44 are a UV light-generating roof lights 58, a pair on both sides of the road 56 arranged lower UV light-generating Side radiators 60a, 60b and a pair on both sides of the road 56 arranged upper UV light generating side radiators 62a, 62b attached. The roof radiator 58 and the four side radiators 60a, 60b and 62a, 62b, each contain, as is more closely indicated by reference numerals for the roof radiator 58, a rod-shaped light source 64. Each UV radiator is also associated with a reflector 66. The rod-shaped light source 64 may also be replaced by a plurality of approximately point-shaped individual light sources.

The UV lamps 58, 60a, 60b, 62a and 62b are attached to the gantry 44 so that their arrangement is approximately the outer contour of the vehicle body 12 corresponds. In the illustrated embodiment, the two lower side radiators 60a, 60b are articulated to the two upper side radiators 62a and 62b so that these lower side radiators 60a, 60b can be automatically adapted to the shape of the lower half of the vehicle body 12, while these are the portal frame 44 passes on the lift truck 46.

For curing of UV paint, which is located on the inner surfaces of the vehicle body 12 and is not accessible from the outside by the UV lamps 58, 60a, 60b, 62a, 62b, an additional UV lamp can be used, which is a mobile , in the interior of the vehicle body 12 insertable robot arm (not shown) is held.

In the area of the bottom surface 45 under the portal frame 44 are connected to the line 42 (see FIG. 1 ) associated outlet nozzles 68a, 68b, from which carbon dioxide can be injected as a protective gas in the gap between the UV lamps 58, 60a, 60b, 62a, 62b and the vehicle body 12 during operation. On the one hand, this protective gas serves to cool the UV emitters 58, 60a, 60b, 62a, 62b and displaces, on the other hand, unwanted oxygen-containing residual gases which lead to ozone formation under the influence of UV light and can impair the polymerization reaction.

In the vicinity of the portal frame 44, the container 38 is lined with a crumpled aluminum foil 73 in order to achieve a high light reflection.

• Es sei angenommen, daß in einer vorgeschalteten Beschichtungseinrichtung der Lackieranlage bereits mehrere Lackschichten aufgetragen worden sind. Bei der obersten Lackschicht handelt es sich um einen Klarlack, der als Pulver auf die bereits vorhandenen Lackschichten aufgebracht ist. Unter dem Einfluß von UV-Licht polymerisiert der Klarlack und härtet auf diese Weise aus. Voraussetzung hierfür ist zum einen, daß der pulverförmige Lack zuvor in einen quasi-flüssigen, gelartigen Zustand überführt wird. Hierzu dient die Vorwärmzone 18, in der eine darin eingebrachte Fahrzeugkarosserie 12 auf eine Temperatur von etwa 90 °C erhitzt wird. Bei dieser Erweichungstemperatur geht das Pulver in den erwähnten gelartigen Zustand über.

The above-described curing apparatus 10 operates as follows:

• It is assumed that several paint layers have already been applied in an upstream coating device of the paint shop. The upper layer of varnish is a clear varnish, which is applied as a powder to the already existing varnish layers. Under the influence of UV light, the clearcoat polymerizes and cures in this way. The prerequisite for this is, on the one hand, that the pulverulent paint is previously converted into a quasi-liquid, gel-like state. For this purpose, the preheating zone 18, in which a vehicle body 12 introduced therein is heated to a temperature of about 90 ° C is used. At this softening temperature, the powder changes to the mentioned gel-like state.

From the preheating zone 18, the carrier 16 with vehicle body 12 placed thereon is moved on the roller conveyor 14 to the inlet lock 34. In parallel, the unloaded pallet truck 46 in the in FIG. 1 shown position and the lifting platform 54 raised so far until it is at the height of the roller conveyor 14. Then, the carrier 16 passes to the vehicle body 12 successively the two roller doors 341, 342 of the inlet lock 34 and thus enters the interior 30 of the cabin housing 28. There, the carrier 16 is taken from the available lifting platform 54 of the lift truck 46.

Subsequently, the lifting platform 54 is lowered by means of the lifting device 52 so far that the pallet truck 46 can ride along with the now arranged thereon vehicle body 12 under the ceiling 37. The vehicle body 12 is located completely within the protective gas atmosphere that prevails in the container 38.

The further procedure is described below on the basis of FIGS. 3a to 3c portrayed. It is in each case in one of the FIG. 1 ajar representation of the interior 30 of the cabin housing 28 with the container 38, the portal frame 44 and the truck 46 shown.

At the in FIG. 3a shown position of the lift truck, the lifting platform 54 is still raised so far that a front flap 70 of the vehicle body 12 with an optimum for the cure target distance of z. B. is spaced about 30 cm from the roof radiator 58, while the lift truck 46 moves in the direction indicated by an arrow 72 direction on the roadway 56. In the course of the further forward movement of the lift truck 46, the lifting platform 54 is lowered so far that now the roof 74 of the vehicle body 12 the desired distance to the roof lights 58 occupies. This condition is in the FIG. 3b shown.

After a further forward movement along the arrow 72, the lifting platform 54 is raised again, as indicated by an arrow 76. As a result, the tailgate 80 can now also be guided past the roof radiator 58 at the desired distance. Once the lift truck 46 has traversed the gantry 44 once in the manner described above, the direction of travel of the lift truck 46 is reversed. The basis of the FIGS. 3a to 3c The procedure shown is then repeated in reverse order. In this way, each part of the side-facing and up-facing surfaces of the vehicle body 12 is exposed twice to UV light irradiation.

After the pallet truck 46 again his in FIG. 1 has reached the starting position shown, the lifting platform 54 is lifted by means of the lifting device 52 so far that the carrier 16 with the vehicle body 12 carried by it on the in the FIG. 1 shown right sub-segment 14b of the roller conveyor 14 can be driven. The carrier 16 with the vehicle body 12 then passes through the outlet lock 36 and leaves the irradiation device 20th

At the end of the carrier 16 is still supplied to the vehicle body 12 of the reheating zone 22, in which a temperature of about 105 ° C prevails. There lingers the Vehicle body 12 for about five to ten minutes in which the polymerization reaction is complete. This time can vary greatly depending on the coating material.

To control these operations, a central controller 90 is provided. In particular, it has the task of controlling the movements of the lift truck 46 in the horizontal direction (double arrow 48) and also perpendicular thereto in the vertical direction (double arrow 49). For this purpose, the controller 90 has a memory 91 in which spatial shape data of the vehicle body 12 are stored. This spatial form data can z. B. are retrieved from a higher-level data processing system, in which all the curing device 10 continuous vehicle bodies 12 relevant data such as the type and color of the paint and body type and shape are deposited. Then only one reading device is needed, which recognizes the type of the incoming vehicle body 12, so that the spatial form data associated with this type can be called up.

Alternatively or for control purposes in addition to this, it is possible to determine the necessary spatial shape data with a measuring device 80 which is disposed within the inlet lock 34 (see FIG. 1 ). The measuring device 80 has a U-shaped frame on which a plurality of optical scanners 82 with infrared light sources in the vertical direction 49 are attached. The optical Scanners 82 detect scanner-like the outer contour of the vehicle body 12 as they pass through the measuring device 80th

However, with less stringent accuracy requirements, it may also be sufficient to design the measuring device as a simple light barrier arrangement, which is arranged in the immediate vicinity of the portal frame 44. The interruption of a photocell then indicates to the controller 90 that the vehicle body 12 is approaching the roof radiator 58 so far that the lifting platform 54 must be lowered. Such a control results in a step-like lifting and lowering movement of the lifting platform 54, since the light barriers do not allow continuous monitoring of the outer contour.

In the FIG. 4 is a lift truck 46 'is shown, in which on a first plane forming support plate 93 which is placed on the lifting device 52, four a rectangular arrangement forming punch 92 are arranged. The punches 92 are hydraulically telescopic and can be extended independently. The upper ends of the punches 92, which form a second plane 95, support the carrier 16. In this way, it is possible, the carrier 16 with the vehicle body 12 mounted thereon both about a transverse axis, as in the FIG. 4 indicated by a double arrow 94, as well as to tilt about a longitudinal axis of the lift truck 46.

Such a tilt about a longitudinal axis is in the FIG. 5 shown to a large extent the FIG. 2 equivalent. Unlike there, however, the side radiators 60a, 60b and 62a, 62b are vertically aligned. A uniform irradiation of the side surfaces of the vehicle body 12 is achieved here by tilting about its longitudinal axis.

The Figures 6a and 6b show in a plan view of the interior 30 according to another embodiment of the invention, in which two pallets 461, 462 in circulating vehicle bodies 12 transport through the portal frame 44. It can also be moved through the system more than two trucks, so that the vehicles are transported and irradiated in a short pitch through the portal frame. In this embodiment, two lanes 561, 562 are also provided, which are separated by a partition 96 from each other. Between the two lanes 561 and 562, a connection can be created in the region of the two end faces of the interior 30 by sliding sliding doors 98, 100 into the partition wall 96, as shown in FIG FIG. 6b is shown.

• Während eine Fahrzeugkarosserie 12 auf dem ersten Hubwagen 461 durch das Portalgerüst 44 gefahren und dabei dem UV-Licht ausgesetzt wird, befindet sich der zweite Hubwagen 462 auf der benachbarten Fahrbahn 562 auf dem Rückweg. Wenn der erste Hubwagen 461 mit der Fahrzeugkarosserie 12 das Portalgerüst 44 passiert hat und die bestrahlte Fahrzeugkarosserie 12 am Ende der Fahrbahn 561 übergeben hat, wird die Schiebetür 100 geöffnet, so daß der Hubwagen 461 seitlich auf die benachbarte Fahrbahn 562 gefahren werden kann. Gleichzeitig fährt in einer Gegenbewegung der leere Hubwagen 462 durch die inzwischen ebenfalls geöffnete Schiebetür 98 hindurch von der zweiten Fahrbahn 562 auf die erste Fahrbahn 561. In dieser Position kann der zweite Hubwagen 462 mit einer zu bestrahlenden Fahrzeugkarosserie 12 beladen werden.

The circulation operation of the two lift trucks 461 and 462 takes place as follows:

• While a vehicle body 12 is driven on the first lift truck 461 through the portal frame 44 and thereby exposed to UV light, there is the second lift truck 462 on the adjacent carriageway 562 on the way back. When the first lift truck 461 has passed the portal frame 44 with the vehicle body 12 and has handed over the irradiated vehicle body 12 at the end of the lane 561, the sliding door 100 is opened, so that the lift truck 461 can be moved laterally onto the adjacent lane 562. At the same time, the empty pallet truck 462 moves in a countermovement through the now also open sliding door 98 through from the second roadway 562 to the first roadway 561. In this position, the second pallet truck 462 can be loaded with a vehicle body 12 to be irradiated.

The above embodiments are used for curing paints under UV light. However, they can also be used in paints which cure under the effect of heat, in particular in an inert gas atmosphere, that is to say for example in a CO ₂ or nitrogen atmosphere. It then essentially only needs to be replaced by the UV emitters described by IR emitters. Other structural changes associated with the change of the electromagnetic radiation are known to the person skilled in the art and need not be explained in detail here.

Claims (41)

1. Apparatus for hardening a coating of an object, more particularly a vehicle body (12), said coating consisting of a material that hardens under electromagnetic radiation, more particularly a UV paint or a thermally hardening paint, comprising

   a) at least one radiator (58, 60a, 60b, 62a, 62b) producing electromagnetic radiation;

   b) a conveying system (14, 16, 46) that moves the object (12) to the proximity of the radiator (58, 60a, 60b, 62a, 62b) and moves it away from said radiator again, and which comprises a truck (46; 46') with a running gear (50), said truck having a platform (54) for receiving the object (12),
   and wherein the at least one radiator (58, 60a, 60b, 62a, 62b) is arranged in such a manner that the truck (46; 46') and the object (12) located thereon can be guided through under the at least one radiator (58, 60a, 60b, 62a, 62b),
   characterised in that
   the truck is a lifting truck and that the platform is a lifting platform wherein the height of the lifting platform relative to the running gear (50) is adjustable by means of a motor.
2. Apparatus according to Claim 1, characterised in that the lifting platform (54) is tiltable relative to the running gear (50) by means of a motor.
3. Apparatus according to Claim 2, characterised in that the lifting platform (54) comprises two planes (93, 95) which are separated from one another by at least one length-variable ram (92).
4. Apparatus according to one of the preceding claims, characterised in that it has a container (38) with an opening (15), through which the object (12) can be guided into the container (38) by height adjustment of the lifting platform (54), and in that the interior space of the container (38) can be subjected to electromagnetic radiation by at least one radiator (58, 60a, 60b, 62a, 62b).
5. Apparatus according to Claim 4, characterised in that at least one radiator is fitted in a wall, a ceiling or a floor of the container.
6. Apparatus according to Claim 5, characterised in that at least one radiator is fitted in the opposite side walls running parallel to the translatory movement of the objects and in at least one of the two end walls running perpendicular to the translatory movement of the objects or in a ceiling or a floor of the container.
7. Apparatus according to Claim 5, characterised in that a multiplicity of radiators are arranged on all walls and in a ceiling or a floor of the container.
8. Apparatus according to one of the preceding claims, characterised in that a plurality of radiators (58, 60a, 60b, 62a, 62b) are arranged on a bridge-like portal frame (44) which has two substantially vertical legs and a substantially horizontal base.
9. Apparatus according to Claim 8, characterised in that the arrangement of the radiators (58, 60a, 60b, 62a, 62b) on the substantially vertical legs of the portal frame (44) is adapted to the course of the lateral surfaces of the object (12).
10. Apparatus according to Claim 7 or 8, characterised in that the arrangement of the radiators (58, 60a, 60b, 62a, 62b) on the substantially horizontal base is adapted to the course of the upward-facing surface of the object (12).
11. Apparatus according to one of Claims 4 to 10, characterised in that a protective gas can be supplied to the interior space of the container (38).
12. Apparatus according to Claim 11, characterised in that the protective gas is heavier than air, in particular is carbon dioxide.
13. Apparatus according to Claim 11, characterised in that the protective gas is lighter than air, in particular is helium.
14. Apparatus according to Claim 12 or 13, characterised in that there is an inlet (68a, 68b) for the protective gas in the immediate vicinity of the at least one radiator.
15. Apparatus according to one of the preceding claims, characterised in that at least one radiator (58, 60a, 60b, 62a, 62b) is assigned a movable reflector (66) on the side facing away from the object (12).
16. Apparatus according to one of Claims 4 to 15, characterised in that the container (38) is at least partly lined with a reflective layer.
17. Apparatus according to Claim 16, characterised in that the layer is uneven.
18. Apparatus according to one of Claims 16 and 17, characterised in that the layer consists of an aluminium foil.
19. Apparatus according to one of the preceding claims, characterised in that it has a booth housing (28) which prevents uncontrolled escape of gases and electromagnetic radiation.
20. Apparatus according to Claim 19, characterised in that a lock (34, 36) for the object (12) isrespectively provided at the inlet and at the outlet of the booth housing (28).
21. Apparatus according to Claim 20, characterised in that an inlet for protective gas is arranged within the inlet-side lock (34) in such a way that a hollow space present in the object (12) is flushed with a protective gas.
22. Apparatus according to Claim 20 or 21, characterised in that a device (42) for removing oxygen from the atmosphere situated within the booth housing (28) is provided.
23. Apparatus according to Claim 22, characterised in that the device (42) for removing oxygen has a catalyst for catalytically binding the oxygen.
24. Apparatus according to Claim 22 or 23, characterised in that the device (42) for removing oxygen has a filter for absorbing oxygen.
25. Apparatus according to one of Claims 22 to 24, characterised in that the device (42) for removing oxygen has a filter for adsorbing oxygen.
26. Apparatus according to one of the preceding claims, characterised in that it has a preheating zone (18) for removing the solvent from the material of the coating.
27. Apparatus according to one of Claims 1 to 25, characterised in that it has a preheating zone (18) for partial gelling of pulverulent material.
28. Apparatus according to one of the preceding claims, characterised in that it has a post-heating zone (22) for completing the hardening.
29. Apparatus according to one of the preceding claims, characterised in that the apparatus comprises a control system (90) which controls the height of the lifting platform (54) in dependence on the upward-facing outer contour of the object (12).
30. Apparatus according to Claim 29, characterised in that the height of the lifting platform (54) can be changed by the control system (90) in such a way that, during a conveying movement of the object (12) past the at least one radiator (58, 60a, 60b, 62a, 62b), the amount of electromagnetic radiation striking the material per unit area, and the intensity thereof, in each case does not fall below predeterminable threshold values required for hardening.
31. Apparatus according to Claim 30, characterised in that the height of the lifting platform (54) can be changed by the control system (90) in such a way that, during a conveying movement of the object (12) past the at least one radiator (58, 60a, 60b, 62a, 62b), the distance in the vertical direction (49) between the object (12) and the at least one radiator (58, 60a, 60b, 62a, 62b) remains at least approximately constant.
32. Apparatus according to Claim 30 or 31, characterised in that the control system (90) comprises a memory (91) for storing three-dimensional shape data of the object.
33. Apparatus according to one of Claims 29 to 32, characterised in that the apparatus comprises a measuring station (80) which is arranged upstream of the at least one radiator (58, 60a, 60b, 62a, 62b) in the conveying direction (48) and by which three-dimensional shape data of the object (12) can be acquired.
34. Apparatus according to Claim 33, characterised in that the measuring station comprises at least one light barrier.
35. Apparatus according to Claim 33 or 34, characterised in that the measuring station comprises a video camera and a device for digital image recognition.
36. Apparatus according to one of Claims 33 to 35, characterised in that the measuring station (80) comprises at least one optical scanner (82), by which the object (12) can be scanned at least in one direction.
37. Apparatus according to Claim 36, characterised in that the optical scanner (82) comprises an infrared light source.
38. Apparatus according to one of the preceding claims, characterised in that the conveying system (14, 16, 46) comprises specifically a lifting truck (46) and a travelling path (56) for the lifting truck (46), along which path the at least one radiator (58, 60a, 60b, 62a, 62b) is arranged, and in that a receiving station for receiving the object (12) on the lifting platform (54) and a delivery station for delivering the object (12) spatially coincide.
39. Apparatus according to one of Claims 1 to 37, characterised in that the conveying system (14, 16, 46) comprises at least two lifting trucks (461, 462) and in that, between a receiving station for receiving the object (12) on the lifting platform (54) and a delivery station for delivering the object (12), two travelling paths (561, 562) for the lifting trucks (461, 462) extend in such a way that the lifting trucks (461, 462) can circulate in a closed circuit between the receiving station and the delivery station.
40. Apparatus according to one of the preceding claims, characterised in that the electromagnetic radiation is UV light.
41. Apparatus according to one of the preceding claims, characterised in that the electro-magnetic radiation is IR radiation.

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