SE536336C2

SE536336C2 - Exposure chamber for curing radiation curable coatings

Info

Publication number: SE536336C2
Application number: SE1130124A
Authority: SE
Inventors: Ronny Pihlblad
Original assignee: Pivab Ab
Priority date: 2011-12-20
Filing date: 2011-12-20
Publication date: 2013-08-27
Also published as: SE1130124A1; WO2013095280A1

Abstract

ABSTRACT PIVAOOZ The invention relates to an exposure chamber (1; 21)comprising za plurality' of curved. rods (2; 23; 41, 44)being arranged. so as to define a framework having atleast partially the shape of an ellipsoid or anellipsoidal segment. The framework forms part of a cage(8; 24; 40) defining a space for housing at least onevehicle component. The exposure chamber further comprisesa plurality of radiation sources (14) attached to one ormore of said rods (2; 23; 41, 44) for applying radiationin said space. The exposure chamber (1; 21) furthercomprises at least one piece of flexible sheet material(10; 26) covering at least a part of said cage (8; 24;40) and having a radiation reflecting side facing said space for reflecting radiation from said radiation sources (14).

Description

The invention relates to an exposure chamber for hardening radiation-curable coatings on vehicle components.

BACKGROUND OF THE INVENTION It is common. practice within the vehicle industry' to applyradiation-curable coatings, such as light- and UV-curablecoatings, to vehicle components, to improve surface propertiesof said components, such as appearance, corrosion resistance and scratch resistance.

Light- or UV-curable coatings require irradiation with high-energy radiation for hardening. In this context, it isimportant that the radiation is applied to all regions of the painted surface as evenly as possible.

US 20ll/0274855 Al relates to a coating device for coating acomponent, e.g. a motor vehicle body. The coating devicecomprises an exposure chamber comprising a substantiallyspherical or ellipsoidal interior. The exposure chamber isprovided. with UV-reflecting teflon plates, for distributing the radiation as evenly as possible over the component.

DE l0 2008 014 378 Al relates to a spherical exposure chamberfor a component, said exposure chamber being' provided. withsuitable reflector modules. The modules are preferablyaccessible and. exchangeable fronl the outside. The shapes ofthe exposure chamber and the reflectors ensure that theradiation is distributed evenly and equally strong to all surfaces of the component.

There are disadvantages with the prior art exposure chambers.Most importantly, the prior art exposure chambers are difficult to assemble and disassemble.

OBJECT OF THE INVENTION It is the object of the invention to provide an exposure chamber, which is easily assembled and disassembled.

DESCRIPTION OF THE INVENTION The object is achieved with an exposure chamber as defined in claim l.

Claim l relates to an exposure chamber for hardeningradiation-curable coatings on vehicle components. The exposurechamber comprises a plurality of curved rods being arranged soas to define a framework having at least partially the shapeof an ellipsoid or an ellipsoidal segment, e.g. a sphere or aspherical segment. The essential idea is to provide a cagedefining curved surfaces having a focal point towards theinterior of the chamber and the geometric configuration ofthese surfaces covered by the present invention also comprisesparabolic or concave shapes or shapes reminding of these. Theframework forms part of a cage having a top and a bottom anddefining a space for housing at least one vehicle component.The exposure chamber further comprises a plurality ofradiation. sources attached. to one or more of said. rods forapplying radiation in said space. The exposure chamber alsocomprises at least one piece of flexible sheet materialcovering at least a part of said cage and having a radiationreflecting side facing said space for reflecting radiation from said radiation sources.

The piece(s) of flexible sheet material are manageable andeasily wrapped around, mounted on and/or attached to the cage.

This makes the exposure chamber easier to assemble and disassemble. Moreover, the demounted piece(s) of flexiblesheet material can be folded and stored in a simple and space-saving way. The piece(s) of flexible sheet material are alsoless expensive in comparison with. prior art solutions. Thepiece(s) of flexible sheet material can be arranged toentirely cover the cage or at least covering all openings inthe cage through which radiation can escape to the outside ofthe cage. The piece(s) of sheet material can also be arrangedto partially cover the cage, a suitable arrangement forexample when the cage comprises reflective parts that do nothave to be covered with a reflective material. Such an examplemay be an essentially spherical cage having a flattened, reflective lower surface defining the bottom of the cage.

In one advantageous embodiment the exposure chamber comprisesonly one piece of flexible sheet material. A single piece offlexible sheet material is easy' to handle. Having only onepiece of flexible sheet material also eliminates the risk ofradiation. escaping' through. openings in a covering structurecomprising a plurality of pieces of flexible sheet material.In order* to obtain. a good. fit around. the cage, the singlepiece of flexible sheet material can be provided in the shapeof an elongated piece of flexible sheet material that iswrapped around the cage, where after the ends of said piece offlexible sheet material are releasably attached to oneanother, for example by means of one or more mechanicalattachment means, e.g. snap fasteners or Velcro. It is alsopossible to drape the cage in a single piece of flexible sheetmaterial by placing the single piece of sheet material abovethe cage and let it fall down to cover the outside of saidcage. A single piece of flexible sheet material can consist ofa plurality of segments attached to one another in order to ensure a tight fit around the cage.

In another advantageous embodiment the exposure chambercomprises a jplurality' of pieces of flexible sheet material.These pieces are easily tight-fittingly attached to cage, so that radiation is reflected towards the center of the cage.

The pieces of flexible sheet material are advantageously(sealingly) attached to one another, to prevent radiation fromescaping from the cage through openings between said pieces of sheet material.

In order to ensure a tight fit around the cage, ensuring thatthe radiation is reflected towards a specific part of thespace defined by the cage, e.g. the center portion, thepiece(s) of flexible sheet material may be elastic orincorporate one or more elastic elements. The piece(s) ofsheet material can also be attached to the cage by means of suitable attachment means, e.g. snap fasteners.

Another advantage with the piece(s) of flexible sheet materialis that one does not have to remove an entire piece offlexible sheet material when a vehicle component is to beinserted into the cage. The piece(s) of flexible sheetmaterial can, for example, be provided with one or morepreferably closeable openings or one can simply lift up aportion of one or nwre pieces of flexible sheet material to gain access to the interior of the cage.

It is advantageous if the rods are detachable from theframework. This makes the exposure chamber easy to assembleand dismount. Dismounted exposure chamber components alsorequire less storage space in comparison with an assembled exposure chamber.

The cage can also comprise one or more intermediate elements,for example plates such as a bottom plate forming a truncatedsphere while serving as an attachment means for the lower partof a plurality of rods, to which attachment means one or moreof the rods are fixedly or removably attached. Theseintermediate elements preferably have a reflective surfacefacing the space, so that the piece(s) of flexible sheetmaterial does not have to cover the entire cage. It ispossible to have one end of a rod attached to a first intermediate element and. the opposite end. of the rod. to a second intermediate element. In one advantageous embodiment, arod is inserted through holes or openings in said intermediateelement(s), so that the rod. can. be removed. therefron1 or* berotated. in the framework for enlargement of an opening forinsertion. of the vehicle component. It is also possible toprovide the exposure chamber with top and/or bottom elements,e.g. plates, which. do not function. as intermediate elementsfor connecting rods but have a reflective surface facing thespace within the chamber for reflecting radiation in saidspace. These elements can also function as platforms forsupporting said vehicle components. These arrangements havethe advantage that the piece(s) of flexible sheet material do not have to cover the entire surface of the cage.

It is important that at least a portion of the framework has acurved shape, so that the radiation from the radiationsources, as well as the radiation reflected by the piece(s) offlexible sheet material, is directed towards the part of thespace within the exposure chamber where the at least onevehicle component is to be located, e.g. the center* of thecage. Therefore, the framework according to the invention hasat least partially the shape of an ellipsoid, such as asphere, or an ellipsoidal segment, for example a sphericalsegment, or a jparabolic or concave surface. An ellipsoidalsegment can have the shape of a truncated. ellipsoid. e.g. atruncated sphere. Advantageously, the framework has the shapeof a sphere, ellipsoid or an egg. The same is true for thecage comprising the framework. The cage can have the shape ofan ellipsoid or a truncated ellipsoid or have the shape of anegg. Advantageously, the space within the cage and thepiece(s) of flexible sheet material have a shape providingonly one or two focus points, so that the radiation emitted bythe radiation sources is concentrated towards the component(s)located at said focus points (the focus point in a sphere islocated at the center of the sphere). This provides for a moreefficient energy use. The cage and/or framework can also haveone or more flattened surfaces. For example, a cage can comprise one or more flattened intermediate elements, e.g. plates, for attachment of the rods. These intermediateelements can have a curved and advantageously reflectiveinside facing the space within the cage and an opposite,flattened outside.

At least some of the radiation sources, e.g. UV-lamps or IR-lamps, are attached to one more of said rods. The radiationsources can for example be attached to the side of the rodsfacing the space within the cage. Alternatively, the radiationsources are located within the rods or attached to other sidesof the rods. Radiation sources can also be attached to otherparts of the exposure chamber, such as the intermediateelements. The radiation sources are advantageously evenlyspread around the perimeter of the cage, to ensure that allsurfaces of the vehicle components placed. in the cage areevenly' radiated. Another advantage with. this arrangement isthat the radiation sources do not have to be removed from thepiece(s) of flexible sheet material when the piece(s) offlexible sheet material is removed from the cage, nor attachedto the piece(s) of sheet material when the piece(s) offlexible sheet material is mounted on the cage. The radiationsources can remain attached to the rods when these areassembled. or disassembled. Alternatively, the radiationsources do not remain attached. to the rods when these areassembled or disassembled, for practical reasons or to ensurethat the radiation sources are not damaged during these procedures.

In one embodiment, the cage has the shape of an ellipsoid,e.g. a sphere. Thus, the radiation will be directed towardsthe part of the space inside the exposure chamber where the vehicle components are to be located.

In another embodiment, the piece(s) of flexible sheet materialforms part of a covering structure enclosing the entire space,ensuring that as much radiation as possible remain inside said space.

In yet another embodiment, the exposure chamber comprises atleast one platform, preferably a radiation-permeable platform,for supporting said. vehicle component, or for supporting asupport structure, e.g. a rack, carrying said vehiclecomponent. The platform is located within said space. It ispossible to have a platform supported by the framework.Alternatively, the platform can be supported by, for example,a shaft extending from. the platforn1 to the outside of thecage. It is advantageous to use a platform, so that thevehicle component can be placed near the focus point(s) of thecage (in the case of a sphere at the center of said space).The platform can for example be located at a height above thebottom of the cage corresponding to about l/3 of the entireheight of the cage. However, the platform can also be locatedin other places within the cage, e.g. near the bottom of thecage. The jplatfornl can also function as a. botton1 plate orintermediate element. It is also preferable, though notnecessary, that the platform, when located within theframework, is radiation permeable. This makes it possible toradiate the vehicle component from all sides (radiationsources are advantageously located on both sides, above andbelow, of the platform). Support structures are advantageousin that they can carry more than one vehicle component (makesthe vehicle components easier to handle) and in that theyensure that all surfaces of the vehicle components are exposedto radiation (e.g. by creating a distance between theradiation sources and the vehicle components and by beingradiation permeable). If the material of the platform isradiation permeable, e.g. plastic or glass, the platform can be made as a solid plate.

In one embodiment, the platform is a grating. A grating cancomprise a plurality of bars made of a suitable material, e.g. a metal but also a radiation permeable material.

In another embodiment, the platform and said radiation sourcesare rotatable relative one another. The platform can be rotatable within said cage and/or the cage can be rotatable around said platform. The important thing is that the vehiclecomponent is rotatable relative said radiation sources, sothat radiation. is applied. as evenly' as possible to as many surfaces of the vehicle component as possible.

It is possible to have two or more radiation-permeableplatforms in one exposure chamber. For example, an ellipsoidcage has two focus points and it is therefore suitable to havetwo platforms within such a cage, located at said focus points.

In one embodiment, at least one piece of flexible sheetmaterial is provided with at least one closeable opening forreceiving said at least one vehicle component. This embodimentis advantageous in that no exposure chamber components have tobe entirely removed from the exposure chamber when the vehiclecomponent is to be inserted into the cage. The piece offlexible sheet material advantageously comprises at least oneopenable portion, e.g. a flap (nr a door, advantageously cutout in the piece of flexible sheet material, which can beunfolded to expose an opening for receiving said at least onevehicle component. Since the flap advantageously' is made ofthe same material as the piece of flexible sheet material, theinside of the flap will reflect radiation into the spacewithin. the cage. Alternatively, the flaps can. be completelyremoved from the piece of flexible sheet material when avehicle component is to be placed. in the cage. It is alsopossible to remove or lift a piece of flexible sheet materialto gain access to the interior of the exposure chamber or tocover the opening in the piece of flexible sheet material witha piece made of a different and preferably reflective material.

In another embodiment, as mentioned above, the at least one ofsaid rods is detachably attached to said framework, forcreation of an opening for receiving at least one vehiclecomponent. Alternatively, said rod is displaceable relative said framework. For example, the rod can be mounted in grooves in the intermediate element(s), said grooves running in acircumferential direction of the cage, so that the rod can bedisplaced towards an adjacent rod along the periphery of thecage. It is also possible to have a rod rotatably mounted insaid framework, so that rotation of the curved rod creates anenlarged. opening' in said framework between said. rod. and anadjacent rod. It is possible to have more than one rodrotatably' mounted. in said framework. An advantage with thedisplaceable and/or rotatable rod is that it becomes possibleto enlarge an opening in the framework without removing any ofthe rods. This makes it easier, in comparison with prior artexposure chambers, for an operator of the exposure chamber toplace a vehicle component in said exposure chamber, especiallywhen combined with an opening in said piece of flexible sheet material, as described above.

It is mentioned. above that the piece(s) of flexible sheetmaterial advantageously has a tight fit around the cage.However, it is possible to use one or more pieces of flexiblesheet material, which do not have a tight fit around the cage, or have folded portions when mounted on said cage.

The framework has at least one opening for insertion ofvehicle components. This opening is preferably defined by tworods located next to one another. These rods can, but do nothave to, be located further apart from one another incomparison with the other rods. It is also possible to let theopening be defined by two rods with one or more rods locatedin between said rods. The rods located in between the two rodsare shortened and the ends of said rods define an upper and/orlower side of the opening. The opening in the framework isadvantageously' but not necessarily' covered. by at least onepiece of flexible sheet material, a part of which can be removed or unfolded to expose the opening in the framework.

Although the exposure chamber has been exemplified for vehicle components, it is obvious that the chamber may be used for any lO object, having' a suitable shape and size, provided with a radiation-curable coating.

The piece(s) of flexible sheet material can be mounted on thecage in many different ways. For example, it is possible tohave rods located. on the inside and/or the outside of thepiece(s) of flexible sheet material. It is also possible tohave pieces of flexible sheet material attached to said rods,so that each piece of flexible sheet material covers the space between two rods.

An exposure chamber according to the invention is preferablyarranged in the vicinity of or directly connected to a coatingchamber, where the vehicle components are provided withradiation-curable coating, so that the vehicle components canbe easily and quickly transferred (automatically or manually) from the coating chamber to the exposure chamber.

An exposure chamber according to the invention advantageouslyhas a diameter of 2.l - 2.3 m and comprises about 8-l2 rods.This does not exclude exposure chambers with larger or smallerdimensions and/or fewer or more rods. The opening in theframework advantageously has a height of about l.2 m.Horizontal distancing elements can be provided between the rods.

Finally, the exposure chamber can be made airtight, so thatthe exposure chamber can be filled with a gas, e.g. an “inert”gas. The term “inert gas” covers gases or gas mixtures with areduced inhibitor content for a radical polymerization of theradiation-curable coatings. Such gases include in particularnitrogen, argon or carbon dioxide with an oxygen content of less than 5% by volume.

SHORT DESCRIPTION OF THE DRAWINGS Below follows a short description of the drawings: ll Fig. l shows a first embodiment of the invention;Fig. 2 shows a second embodiment of the invention; Fig. 3 shows a third embodiment of the invention; DETAILED DESCRIPTION OF THE INVENTION The following' paragraphs explain the meaning' of some terms used throughout this application.

A rod is an elongated structural element. A rod can bestraight or curved. A rod can also consist of a plurality ofsmaller segments connected to one another so as to form a rod.For example, it is possible to attach a plurality of straight segments to one another to form a curved rod.

The term radiation source refers to a source of radiation forcuring radiation-curable coatings on vehicle components.Examples of suitable radiation sources are e.g. UV-lamps, IR-lamps or heating elements. It is possible to use more than onetype of radiation source in the same exposure chamber. UR-radiation is advantageous in that a component can be cured in about 3-4 minutes and at temperatures of about l8-l9°C.

A piece of flexible sheet material is a flexible piececomprising one or more materials arranged in one or more layers.

An ellipsoid is a three-dimensional body that resembles aperfect ellipsoidd An ellipsoid. can be somewhat asymmetric.For example, an ellipsoid can be somewhat truncated. A perfectellipsoid is a type of quadric surface that is a higherdimension analogue of an ellipse. There are many different kinds of ellipsoids, for example spheres.

Our definition of an ellipsoid segment is a three-dimensional body that resembles a perfect ellipsoid segment. l2 A sphere is a three-dimensional body that resembles a perfectsphere. A sphere can be somewhat asymmetric. For example, a sphere can be a somewhat truncated sphere.

A spherical segment is a three-dimensional body that resembles a perfect spherical segment.

An egg-shape is a three-dimensional shape that resembles aperfect egg-shape. An egg-shape can be somewhat asymmetric.For example, an egg-shape can be a somewhat truncated. egg- shape.

The geometrical configurations covered by the presentinvention also include parabolic or concave surfacesreflecting radiation towards the interior of the exposure chamber.

An object attached or connected to another object can bedirectly attached or connected to said object or attached orconnected by means of an intermediate piece. An objectattached to or connected to another object can be removably or fixedly attached or connected to said object.

It is in some places mentioned that the piece of sheetmaterial covers an entire surface area. It is understood thatthis includes embodiments wherein smaller portions of thesurface area remain uncovered. For example, the piece offlexible sheet material can be provided. with. a hole for ashaft.

A displaceable rod can be displaced in its entirety towards oraway from adjacent rods without being removed from theframework of which it is a part. A rotatable rod is rotatablyarranged in the framework, so that the center of the rod ismoved away from or towards an adjacent rod while the ends of said rod remain at the same distance from said adjacent rods. 13 The invention will now be described in detail with reference to the drawings.

Fig.1 shows a first embodiment of an exposure chamber 1according to the invention. The exposure chamber comprises aplurality of rods 2 connected to one another so as to form aspherical framework. The rods 2 have a curvature and definebetween them. a space 5 for receiving one or more vehiclecomponents (not shown). The framework forms part of a cage 8surrounding said space 5. The cage 8 has the shape of a sphere.

The exposure chamber* 1 also comprises a radiation-permeableplatform 9 located within the framework, on which the vehiclecomponents are to be placed before the curing process begins.In this embodiment, the platform. is made of a radiation-permeable material mounted on a rotatable shaft 7 attached toa driving means 3. The shaft 7 and driving means 3 areschematically' shown in Fig. 1. One advantage with using aradiation-permeable platform 9 is that the vehicle componentslocated. on the platform. 9 can be radiated from. below theplatform 9. The rotatable shaft 7 is capable of rotating theplatform 9 relative the cage 8, so that the surfaces of thevehicle components located on the platform 9 are evenly exposed to radiation.

Radiation sources 14 in the form of UV-lamps are attached tothe rods 2. Note that some radiation sources 14 (schematicallyshown) are located below the platform 9. The UV-lamps 14 areevenly distributed around the perimeter of the cage 8, to makesure that all areas of the vehicle components located on the platform 9 are evenly radiated.

The cage 8 is covered. by' a single piece of flexible sheetmaterial 10. The single piece of flexible sheet material 10 isprovided in the form of an elongated piece, which is wrappedaround the cage 8 and the ends of which are attached to one another by means of suitable attachment means 11, e.g. snap 14 fasteners. The framework is provided with an opening 18 forreceiving the vehicle components. The opening 18 in theframework is created by increasing the distance between twoadjacent rods. A corresponding opening 16 is cut out in thepiece of flexible sheet material 10, so that the vehiclecomponents can be inserted into the exposure chamber 1 throughthe openings 16, 18. The opening 16 in the piece of flexiblesheet material 10 is covered by a flap 17 attached at one sideto the piece of flexible sheet material 10, which flap 17 can be unfolded to expose the opening 18 in the framework.

Fig. 2 shows an ellipsoidal exposure chamber 21 comprisingrods 23 forming part of a framework forming part of a cage 24.The exposure chamber 21 in Fig. 2 has one intermediate element31 located at the bottom of the cage 24 and to which the rods23 are attached. The intermediate element 31 has a curved andreflective inside surface facing the space within the cage 24.The exposure chamber further comprises two radiation-permeableplatforms 22 supported by shafts 35. In this embodiment, thecage 24 is rotatable around the platforms 22 by means of adriving means 25 (schematically shown). Note that in thisembodiment, UV-lamps can also be attached to the intermediate element 31.

The cage 24 is covered by a plurality of pieces of flexiblesheet material 26 attached to the rods 23 by means of suitableattachment means 27, e.g. snap fasteners. The pieces offlexible sheet material 26 are attached side by side on thecage 24, extending from the intermediate piece 31 to a top ofthe cage 24, so that they cover all openings in the framework through which radiation can escape.

Two of the pieces of flexible sheet material 26 are providedwith flaps 28 and openings 29 similar to the flap and openingshown in Fig. 1. The framework in Fig. 2 is also provided withtwo openings 30 corresponding to the openings 29 in the piecesof flexible sheet material 26.

Finally, in Fig. 3, is shown a spherical cage 40 withoutpieces of flexible sheet material. One of the rods 4l in Fig.3 is rotatably mounted in upper and lower intermediateelements 42, 43, so that it can be rotated in said cage 40 andits center portion be removed from location A to location B orC and thereby increase or decrease the space between itselfand an adjacent rod 44. In an alternative embodiment (notshown), the rod. is displaceable along the periphery' of the cage.

Note that the scope of the invention is not limited by theabove described embodiments. The features described above canbe combined in many different ways. For example, one or moreof the rods in Fig. l and 2 can be rotatable or displaceablerelative the other rods. The exposure chambers in Fig. l and 2can be provided with any number of intermediate members andthe cage in Fig. 3 can be covered. one or more pieces of flexible sheet material.

Claims

PIVAOO2

1.An exposure chamber (1; 21) for hardening radiation-curable coatings on vehicle components, said exposurechamber (1; 21) comprising: - a plurality of curved rods (2; 23; 41, 44) beingarranged. so as to define a framework having at leastpartially' the shape of an ellipsoid. or an ellipsoidalsegment, e.g. a sphere or a spherical segment, saidframework forming part of a cage (8; 24; 40) defining aspace for housing at least one vehicle component; - a plurality of radiation sources (14) attached toone or more of said rods (2; 23; 41, 44) for applyingradiation in said space; characterized in that said exposure chamber (1; 21)further comprises: - at least one piece of flexible sheet material (10;26) covering at least a part of said cage (8; 24; 40) andhaving a radiation reflecting side facing said space for reflecting radiation from said radiation sources (14).

2.An exposure chamber (1; 21) according to claim 1, whereinsaid cage (8; 24; 40) has the shape of an ellipsoid, e.g. a sphere, or an egg.

3.An exposure chamber (1; 21) according to claim 1 or 2,wherein said at least one piece of flexible sheetmaterial (10) forms part of a covering structure enclosing the entire space.

4.An exposure chamber (1; 21) according to any of thepreceding claims, comprising at least one radiation-permeable platform (9; 22) for supporting said vehicle component within said space.

5.An exposure chamber (1; 21) according to claim 4, characterized in that said platform (9; 22) is a grating.

6.An exposure chamber (1; 21) according to claim 4 or 5,wherein said platform (9; 22) and said radiation sources (14) are rotatable relative one another.

7.An exposure chamber (1; 21) according to claim 6, wherein said platform (9) is rotatable within said cage.

8.An exposure chamber (1; 21) according to claim 5 or 6,wherein said cage (24) is rotatable around said platform(22).

9.An exposure chamber (1; 21) according to any of claims 4-8, comprising two or more radiation-permeable platforms(22).

10. An exposure chamber (1; 21) according to any of thepreceding claims, wherein at least one piece of flexiblesheet nmterial (10; 26) is provided with at least onecloseable opening (16; 29) for receiving said at least one vehicle component.

11. An exposure chamber (1; 21) according to any of thepreceding claims, wherein at least one of said rods (2;23; 41, 44) is detachable from said framework, forcreation of an opening for receiving said at least one vehicle component.

12. An exposure chamber (1; 21) according to any of thepreceding claims, wherein at least one of said rods (41)is displaceably or rotatably mounted in said framework,for creation of an opening for receiving said at least one vehicle component.