WO2008000317A1

WO2008000317A1 - Installation for treating a workpiece with uv, nir or ir radiation

Info

Publication number: WO2008000317A1
Application number: PCT/EP2007/004404
Authority: WO
Inventors: Kai K. O. BÄR; Rolf Wirth
Original assignee: Advanced Photonics Technologies Ag
Priority date: 2006-06-26
Filing date: 2007-05-16
Publication date: 2008-01-03
Also published as: EP2042002B1; EP2042002A1; DE102006029252A1

Abstract

Installation for treating a workpiece with UV, NIR or IR radiation, with a plurality of radiators emitting UV, NIR and/or IR radiation and at least one reflective surface associated with the radiators with an irradiation chamber, which, over the majority of the inner wall, is clad with a highly reflective, flat composite material, which, on a sheet-metal carrier, has a coating with a reflectance of 97.5% or more for the UV, NIR or IR radiation and thereupon has a transparent oxidic or vitreous anti-corrosion layer.

Description

Plant for machining a workpiece with UV, NIR or IR radiation

description

The invention relates to a system for processing a workpiece with UV, NIR or IR radiation according to the preamble of claim 1 and the use of a highly reflective sheet-like composite material in such a system.

For thermal treatment of surfaces, processing of materials and production of composite materials in the industrial environment irradiation methods are often used in which the irradiation with electromagnetic radiation having a significant active content in the near infrared (NIR), in particular in the wavelength range between 0.8 .mu.m and 1.5 microns, applied and so heated. However, UV or visible radiation is also absorbed by many materials and causes corresponding thermal effects. When UV radiation is used for processing purposes, for example for drying the printing ink on high-speed print image carriers or for curing special paint formulations, in addition to or primarily prior to its thermal action, its crosslinking-initializing effect is of particular importance for certain polymers.

It is known, for example, the use of irradiation arrangements for drying paints, such as liquid or powder coatings on metal, wood, paper or plastics, cf. the patents DE 100 48 361 Cl or DE 101 08 926 Cl of the applicant. Even for drying paints, printing inks, glazes or oils, the coated substrate is subjected in many cases to radiation which penetrates into the coating and partly also into the substrate; for further information on this reference is made to the patent DE 100 38 896 B4 of the Applicant. Also for stretch blow molding of plastic products, such. PET containers, corresponding preforms are exposed to radiation; Details can be found for example in the patent DE 197 36 462 C2 of the applicant.

In the realization of applications of near-infrared irradiation arrangements are often counter-reflectors on the radiation source opposite side of the article to be processed and / or side reflectors, if necessary. To form a substantially closed radiation space provided. This applies in particular to applications for irradiating a rapidly conveyed processing object, such as a paper web, a plastic film, a metal strip, an elastomer profile or preforms or the like. This results in substantial improvements in the treated product and in the process control.

The reflectors form walls of an irradiation zone or a radiation space. Corresponding arrangements can be found, for example, in the patents DE 198 07 643 C2 and DE 198 57 044 C2 and in the published patent applications DE 100 51 641 A1 and DE 100 51 642 A1 of the applicant. The unpublished German patent application 10 2005 000 837.2 of the applicant finally describes the special lining of a radiation room with tile-like reflector plates with reflective front and radiating back.

The present invention is based on this prior art, the task of specifying a further improved system of the generic type, which can be very simple and works with high energy efficiency.

This object is achieved by a system having the features of claim 1. Advantageous developments of the inventive concept are the subject of the claims dependent thereon. In the context of the solution of this task are also a new use according to claim 18 and their embodiments in the dependent claims therefrom.

The invention includes the essential idea of an improvement of the reflection properties of the workpiece environment driven to the limits of the practically feasible, in order to minimize energy losses which still occur there (and on the whole quite considerable) in known systems. As a result, it is possible to a surprisingly high extent, by multiple reflections also a multiple loading of the workpiece with there not yet become effective to achieve sharing of work radiation. Even with workpieces with unfavorable reflection properties for working radiation, efficiencies of over 40%, based on a typical workpiece coating, of over 70% (thermal) can be achieved.

Of course, the considerable increase in the system efficiency possible according to the invention increases the energy yield on the one hand, but it is also reflected in reduced process and thus product costs, because the cooling devices of such a system can be dimensioned smaller or, if required, particularly costly cooling (liquid cooling) . in favor of less expensive cooling method (forced air cooling) can be dispensed with.

To implement this principle, the invention further includes the idea of lining the inner wall of an irradiation chamber at least for the most part - preferably as completely as possible - with a highly reflective composite sheet material, which has its excellent reflection properties even with the usual high thermal load and in plant continuous operation reserves. In this sense, a composite material is provided which has on a metal sheet support a coating having a reflectance of 97.5% or more for the UV, NIR or IR radiation and then a transparent oxide or glassy corrosion protection layer.

In a first advantageous embodiment, it is provided that the carrier of the highly reflective sheet-like composite material consists of aluminum or an aluminum alloy. Aluminum sheet is well suited as a substrate for highly reflective coatings and for components with the purpose in question also because of its high thermal conductivity, low cost and easy workability. Alternatively, steel or copper or, for special applications, other metal sheets may also be considered as carriers of the composite material.

An advantageous coating material with particularly good reflective properties is silver with a high degree of purity, or else a silver alloy (such as with Gold). Because of the tendency to corrosion, however, an Ag reflection layer places high demands on the quality of the covering corrosion protection layer, so that a coating of the carrier with ultrapure aluminum is to be regarded as a suitable solution, in particular when using Al sheet metal as the carrier. The application of the coating to the carrier is carried out in an expedient manner using known vacuum coating methods.

Since even with very high reflectance - preferably values of over 99% - when using high-power radiators heats the reflector material to a considerable extent, advantageously the back of the sheet metal support for improved heat radiation is darkly colored, especially blackened. This promotes the heat radiation from the composite material or, in conjunction with a fluid flow cooling of the back, and the heat dissipation or convection from there.

Especially in connection with a back-side cooling, but also independently thereof for structural and maintenance-side reasons, a structure of the radiation chamber is advantageous in which the composite material of the outer wall of the irradiation chamber with a predetermined distance, in particular mounted on a support structure, is vorgeblendet.

In the interest of optimized overall reflection properties, it is preferred that the irradiation chamber is optically closed substantially on all sides. As already mentioned above, for this purpose it should also be as completely lined as possible with the reflector material proposed here.

In a further development of this idea, it is provided that the irradiation chamber for processing a continuous workpiece, in particular in the form of a sheet or a quasi-endless strip, has an inlet and outlet area adapted to the dimensions of the workpiece with a low tolerance, to which optical sealing means for avoiding associated with radiation leaks. Alone already a strictly on the functionally essential or required by the user tolerances sizing of the inlet and outlet area ensures the reduction of radiation leaks. In addition, in this direction, the provision of suitable "optical sealant" has, in particular an inlet and / or outlet slope or curve, which is occupied or veneered at least in sections with the highly reflective sheet-like composite material.

To realize optimum overall reflection properties even in different situations of use or with changing user requirements is further provided that the input and / or outlet slope or curve are assigned adjusting means for adjusting their inclination angle and / or the input and / or outlet more Having sections with different, optionally separately adjustable inclination angle.

An advantageous embodiment of the above-mentioned simple and inexpensive cooling systems is that the irradiation chamber comprises a gas circulation cooling, which comprises the generation and guidance of a cooling gas flow on a surface of the lining sheet-like composite material, in particular its back, and after heating of the gas over a workpiece surface. This ensures that not only the working radiation is supplied as completely as possible to the workpiece, but that the unavoidable in the reflector converted into heat radiation components of the heating of the workpiece benefit. It is understood that an alternative which is sensible under suitable conditions of use may consist in a removal of the heated air from the irradiation chamber and in its other use outside the chamber, for example to preheat the workpiece.

It should be noted that in the appended claims and the description, the term "workpiece" is to be understood in its most general sense of a processing object, so also quasi-endless sheets or non-formgebundene media, such as a particle or liquid flow to include , It should also be noted that in the designation of UV, NIR or IR radiation of the range of visible radiation lying between these areas is by no means excluded, as long as the visible light has a processing function with respect to the workpiece. For certain applications in which, for example, solvents or other constituents emerge from the workpiece or a coating arranged thereon during the irradiation, an embodiment of the system is expedient in which in the irradiation chamber between the radiators and / or the laminar composite material and the workpiece a highly transparent for the UV, NIR and / or IR radiation used protective screen is arranged. The protective screen prevents contamination of the radiator and / or the reflector material. It goes without saying that it is then self-polluted and must be cleaned at certain intervals. This can be facilitated by a chamber construction in which the protective pane can be removed or moved or easily opened by unfolding it. In combination herewith, or independently of this, furthermore, a chamber structure is advantageous in which the lining highly reflective composite material can be easily cleaned and / or replaced at least in sections. Concrete design features of such a radiation chamber but are not the subject of the present invention.

In the interest of the basic aim of introducing the working radiation as completely as possible into the workpiece, it is advantageous if the protective pane is provided with a coating which reduces the reflection used for UV, NIR and / or IR radiation at least on the surface facing the radiators ,

In a structurally particularly simple and thus also particularly cost-effective embodiment of the proposed system is provided that a thermal insulation of the irradiation chamber is at least predominantly effected by the highly reflective sheet-like composite material. This concept, which can also be referred to as "light weight thermal insulation", is thus the decoupling between high thermal radiation zone and protected against high temperatures environment to be protected largely achieved by the excellent reflection properties of the inside of the irradiation chamber, and on the use voluminous and largely Manually processed thermal insulation materials can be largely dispensed with. This is particularly well achieved when the thermal insulation to the effect of hochrefflek- lining the irradiation chamber supporting surface composite material is supported by a sweeping along the surface of the cooling gas flow. But even without a back-side cooling gas flow, solely by arranging the reflector material at a distance from the irradiation chamber outer wall, the comparatively good thermal insulation properties of air can be used to realize the aforementioned lightweight construction concept.

The extremely high efficiency and the possible lightweight design mean that the proposed device has a low thermal mass and therefore is particularly fast in their temperature controllable. On the other hand, the low thermal mass but also requires a fast and high-precision temperature control to compensate for temperature fluctuations of the supplied workpiece or the environment quickly without adverse effects on the quality of the final product can. Therefore, suitably, the radiators are assigned a substantially inertia-free power control for setting a process temperature in the irradiation chamber.

Incidentally, advantages and expediencies of the invention will become apparent from the following description of preferred embodiments and aspects of the invention with reference to the figures. From these show:

1 shows a first embodiment of a system according to the invention in a schematic longitudinal section,

Fig. 2 shows a second embodiment of a system according to the invention in a schematic longitudinal section and

Fig. 3 is a cross-sectional view of an embodiment of the planar composite material used in the inventive system as a reflector.

1 schematically shows a drying plant 1 for drying coatings on a rapidly passing metal sheet (coil) 3 by means of near-infrared Radiation emitted by filament halogen lamps 5 operated at high radiator temperature above 2900 K.

The plant 1 comprises an irradiation chamber 7, in which the metal sheet 3 is supported by rotating rollers 9 and which has an inlet region 11 and an outlet region 13, in which no emitters are arranged. In this case, the inlet area 11 also serves as a preheating area, while the outlet area 13 can act as a post-tempering zone.

The central region of the plant, the actual irradiation chamber 7 has in the illustrated embodiment substantially trapezoidal shape with a continuous metal sheet 3 and the bottom wall 7.1 parallel ceiling wall 7.2 and at an obtuse angle to the bottom wall 7.1 inclined end walls 7.3. The inlet and outlet areas 11, 13 are closely matched in their passage width to the tolerances specified for the fast passage of the sheet 3, wherein the inside width of the inlet area 11 is dimensioned slightly larger than that of the outlet area 13 for a reason to be explained below. The tops of both areas are slightly inclined with respect to the plane of the sheet 3.

Virtually the entire inner surface of the irradiation chamber 7, as well as the tops of the inlet and outlet areas 11, 13 are lined with a highly reflective sheet material 15. This is mounted by a suitable support structure 17 spaced from the wall of the irradiation chamber 7, while it is placed directly on the upper wall portions of the inlet and outlet region 11, 13 at attachment points 19. Also in the spaces between the rollers 9, the reflector material 15 is provided on suitable stands 19.

In the transition region between the inlet region 11 and the irradiation chamber 7, an air inlet 21 is provided in the end wall there, via the fan air in the space between the reflector material 15 and the outer wall of the irradiation chamber 7 in the flow direction indicated in the figure with arrows. blown. After passing through the back of the radiator 5 surrounding and particularly strong heating sections of the reflector construction 15/17 the air, supported by suitable shaping of the reflector units and a (not shown) suction at the outer end of the inlet region 11, on the surface of the metal sheet. 3 and flows counter to its direction to the suction point at the outer end of the inlet region 11. It causes an additional heating of the surface of the sheet and thereby cools even in the inlet region 11 slightly from.

Due to the almost complete lining of all wall areas of the irradiation chamber 7 and the more important sections of the inlet and outlet area 11, 13 with the sheet material 15 with extremely good and stable reflection properties, in conjunction with the narrow dimensioning of the inlet and outlet area, succeeds an outstanding efficient utilization the NIR radiation of the radiator 5. The thermal efficiency of the assembly is further increased by the return of behind the reflector surfaces along sweeping cooling air over the workpiece surface. In addition, due to the particularly effective back reflection of the working radiation, in connection with the special cooling air guide, a special heat insulation of the irradiation chamber 7 can be largely dispensed with.

Fig. 2 shows a further embodiment of a processing plant according to the invention a here designated by the numeral 1 'modification of Appendix 1 of FIG. 1, for drying and / or crosslinking of a coating on a metal sheet 3. As far as this Appendix the same or functionally matching parts as the Appendix 1, these are denoted by the same reference numerals as in Fig. 1 and will not be explained again here. A significant constructive difference is that the irradiation chamber T curved in this embodiment to the ceiling wall molded (not separately designated in the figure) end wall areas, their wall in the upper area so as a vault 7.2 'is executed. This part of the irradiation chamber is covered with surface reflector material 15 lying directly on the wall, which is connected to attachment points 19 with the wall. In the inlet area 11 'and outlet area 13' is a massive upper or top wall omitted and only free elevated flat reflector material 15 is provided. While this is fixedly mounted in the outlet region 13 ', its inclination is adjustable by suitable adjusting means 23 in the inlet region 11'.

A cooling air supply is in this embodiment at the transition between the irradiation chamber 7 'and the outlet region 13' and is here designated by 21 '. As shown by the course of the arrows, the cooling air flows substantially only along the surface of the metal sheet 3 to the inlet region 11 'and is sucked out there; an air cooling of the reflector surfaces 15 is thus not provided here; but it may be separate (not shown) cooling means for the radiator 5 may be present.

3 shows schematically the cross-section of an embodiment of the highly reflecting surface material 15 used for lining the irradiation chambers. This is on a high-quality Al sheet 15a by vacuum deposition of a purest Al layer 15b with a purity of at least 99.99%. and subsequent deposition of a highly transparent SiO ₂ layer 15c on the reflection layer 15b and provided on the surface of the support 15a opposite the reflection layer 15b by anodization with a firmly adhering black layer 15d.

The embodiment of the invention is not limited to the construction example shown here and the illustrated preferred structure of the highly reflective sheet-like composite material, but also in a variety of modifications possible, which are within the scope of professional action. In particular, all possible combinations of the features of the dependent claims should be considered to be within the scope of the invention.

Claims

claims

1. Plant for processing a workpiece with UV, NIR or IR radiation, with a plurality of UV, NIR and / or IR radiation emitting emitters and at least one emitter associated with the reflecting surface, characterized by an irradiation chamber, the predominant Part of the inner wall is lined with a highly reflective sheet composite material having a coating on a metal support with a reflectance of 97.5% or more for the UV, NIR or IR radiation and then a transparent oxide or glassy corrosion protection layer.

2. Plant according to claim 1, characterized in that the carrier of the highly reflective sheet-like composite material consists of aluminum or an aluminum alloy.

3. Plant according to claim 1 or 2, characterized in that the coating of the highly reflective sheet-like composite material consists essentially of silver or ultra-pure aluminum with a purity of 99.99% or more.

4. Installation according to one of the preceding claims, characterized in that the back of the sheet metal support for improved heat radiation dark colored, in particular blackened.

5. Plant according to one of the preceding claims, characterized in that the irradiation chamber is optically closed substantially on all sides.

6. Installation according to one of the preceding claims, characterized in that the composite material of the outer wall of the irradiation chamber with a predetermined distance, in particular mounted on a support structure, is vorgeblendet.

7. Installation according to one of the preceding claims, characterized in that the irradiation chamber for processing a continuous workpiece, in particular in the form of a sheet or a quasi-endless belt, an adapted to the dimensions of the workpiece with low tolerance inlet and outlet region , which are associated with optical sealant to prevent radiation leakage.

8. Plant according to claim 7, characterized in that the optical sealing means have an input and / or outlet slope or curve, which is occupied or veneered at least in sections with the highly reflective sheet-like composite material.

9. Plant according to claim 8, characterized in that the input and / or outlet slope or curve are assigned adjustment means for adjusting their inclination angle.

10. Plant according to claim 8 or 9, characterized in that the inlet and / or outlet slope has a plurality of sections with different, optionally separately adjustable inclination angle.

11. Plant according to one of the preceding claims, characterized in that the irradiation chamber has a gas circulation cooling, the generation and guiding a stream of cooling gas at a surface of the lining sheet-like composite material, in particular the rear side thereof, and after heating the gas over a workpiece surface.

12. Installation according to one of the preceding claims, characterized in that in the irradiation chamber between the radiators and / or the sheet-like composite material and the workpiece is arranged for the UV, NIR and / or IR radiation highly transparent protective screen.

13. Plant according to claim 12, characterized in that the protective screen is provided at least on the surface facing the radiators with a used for the UV, NIR and / or IR radiation anti-reflection coating.

14. Installation according to one of the preceding claims, characterized in that a thermal insulation of the irradiation chamber is at least predominantly effected by the highly reflective planar composite material.

15. Plant according to claim 14, characterized in that the thermal insulation is supported to the effect of the irradiation chamber lining high-reflective sheet composite material by a sweeping along the surface of the cooling gas flow.

16. Plant according to claim 14 or 15, characterized in that in addition to the lining with the highly reflective sheet-like composite material and optionally the cooling gas flow no thermal insulation of the irradiation chamber is provided.

17. Installation according to one of the preceding claims, characterized in that the radiators is associated with a substantially inertia-free power control for setting a process temperature in the irradiation chamber.

18. Use of a highly reflective sheet-like composite material which has a coating with a reflectance of 97% or more for UV, NIR or IR radiation and then a transparent oxidic or glassy anticorrosive coating on a sheet metal support in a system for processing a Workpiece with UV, NIR and / or IR radiation.

19. Use according to claim 18, characterized in that the sheet-metal carrier of the sheet-like composite material consists of aluminum or an aluminum alloy.

20. Use according to claim 18 or 19, characterized in that the coating of the sheet-like composite material consists essentially of silver or of ultrapure aluminum with a purity factor of 99.99% or more.

21. Use according to any one of claims 18 to 20, characterized in that the back of the sheet metal carrier dark colored, in particular blackened, is.

22. Use according to one of claims 18 to 21, characterized in that the laminar composite material of an outer wall of a UV, NIR and / or IR radiators equipped irradiation chamber vorgeblendet in a predetermined distance.