EP1834147B1 - Thermal irradiation system for heating material to be irradiated - Google Patents

Description

The invention relates to a thermal irradiation arrangement for heating an irradiation material, having at least one high-power radiation source for radiation having a substantial active component in the visible and / or IR and / or UV region, in particular in the region of the near infrared, and at least one with the radiation acted upon wall.

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.

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 C1 or DE 101 08 926 C1 the applicant. Also for drying paints, printing inks, glazes or oils, the coated substrate is often exposed to radiation, which penetrates into the coating and partly into the substrate; for more information, see, for example, the patent DE 100 38 896 B4 referred to 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 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 the irradiation zone or the radiation space. Corresponding arrangements are, for example, the patents DE 198 07 643 C2 and DE 198 57 044 C2 and the publications

DE 100 51 641 A1 and DE 100 51 642 A1 to be taken from the applicant. See also DE 27 49 439 A ,

In operation, in particular when using high radiation flux densities (of 200 kW / m ² and more), active cooling of the counter-reflectors and often also of side reflectors proves to be essential to dissipate the heat introduced by the emitters from the radiation space. In spite of the high degree of reflectivity, the reflectors absorb so much radiant energy in the form of heat that their dimensional stability is not readily guaranteed during prolonged use without active cooling.

Very often, the material to be irradiated has volatiles, such as solvents in paints or inks. In many applications, larger quantities of these high-boiling constituents evaporate from the heated irradiation material. These then settle on the cooler parts of the arrangement, in particular on the cooled wall or on the reflectors. There they run along the walls and / or form incrustations. Such contamination affects the functionality of the system, for example. The reflectivity of the wall, and also endanger the quality of the products when adhering to the wall from the wall dripping condensates or chipping deposits on the irradiation. They are also flammable and possibly generate the risk of explosion. Thus, cleaning and polishing work are required, which are time consuming and labor-intensive and require a longer downtime and corresponding costs.

DE 24 05 491 discloses a Heizpaneel, especially for ovens with explosive interior. These heating panels can be quickly assembled and also disassembled, allowing furnaces to be assembled of any size and shape. The heating panels are able to dissipate the pressure in case of an explosion.

US 618 353 discloses an infrared oven having a heating chamber whose walls are provided with openings through which infrared lamps can be directed into the heating chamber. The oven walls are made up of several units, allowing the infrared oven to be quickly and easily assembled from several standard elements.

US 1,115,794 discloses a drying arrangement, which consists of two chambers, wherein in one chamber reflectors are arranged and in the second chamber is cooled air. Both chambers are separated by a wall which contains slots through which the cooled air can pass to bypass the reflectors, thus extending the life of the reflectors and reducing the pollution of the reflectors.

US 2,688,684 discloses an infrared-type drying oven whose interior is lined with plates having a reflective surface and lined in polished stainless steel, aluminum, chromium or cadmium or with enamel, all of which have good radiation-reflecting properties.

US 618 978 discloses a device which generates heat with infrared. The device is thereby assembled from different standardized parts and can thus assume different sizes.

US 5,542,194 discloses a silicon carbide body which also radiates infrared radiation and a corresponding device having this body and used for drying.

DD 8211 discloses a radiation oven for drying a dry material, the irradiation of the dry material is carried out indirectly by the rays of the infrared lamp or the dark radiator are irradiated on an aluminum foil, which in turn reflects the radiation back to the dry matter by reflection.

US 2 419 643 also discloses a furnace structure consisting essentially of standardized elements so that the assembly can be easily adapted to the given needs.

US 6,621,087 discloses a UV radiator which is used to dry UV-curable ink.

EP 0 133 847 discloses a reflector structure that can be placed behind infrared radiation sources, where the reflector surface is made of a ceramic fibrous material.

DE 8 34 970 discloses a radiation dryer with a tunnel-shaped dry dream and electrically heated tubular heaters. Damaged radiators can be easily replaced by openings on the furnace wall.

DE 27 26 387 discloses a UV light assembly having dichroic filters that evaluate a coating on a substrate using an ellipse-like reflector housing.

US Pat. No. 6,242,717 discloses a removable support to which a reflector can be mounted in an oven.

GB 1 489 183 discloses a reflector system having a housing in which a radiator and a reflector are arranged. A control system determines the exit temperature of the cooling liquid previously flowed through the enclosure and thus controls the flow of liquid through the device to maintain the temperature of the radiator at an optimum value.

FR 1 105 713 discloses a drying oven which can be assembled from prefabricated elements.

US 2,559,249 discloses an improved furnace structure wherein parts of the furnace structure are standardized so that the parts can be individually selected and bonded together to obtain a furnace having the desired size, capacity and shape.

The invention is therefore based on the object of specifying an irradiation arrangement of the generic type, which avoids the impairment of the functioning of the arrangement and the quality of the products produced by evaporating constituents of an irradiation material which condense on the wall in a simple and cost-effective manner.

This object is achieved by an irradiation arrangement having the features of claim 1.

The invention includes the essential idea to provide a Vorblendelement, which is mounted on the wall at a distance. The Vorblendelement has an acted upon by the radiation reflective front side and the wall facing radiating rear side.

Specifically, the reflection and radiation properties of the Vorblendelementes are set such that sets a temperature above the temperature of the wall during operation of the irradiation arrangement. This temperature is determined by the thermal equilibrium which results from the absorption of the radiation emitted by the radiation source on the front side and the radiation in the direction of the cooled system parts. The temperature of the Vorblendelementes can thus be adjusted in operation so that a condensation of evaporated volatile compounds from the irradiation and thus the formation of encrustations and / or impairing the reflectivity of the elements soiling is prevented or at least limited. If necessary, the influence (convection) of heated process air must also be considered.

In a preferred embodiment of an irradiation arrangement according to the invention, the front side of the Vorblendelementes is highly reflective. This is advantageous for the radiation space limiting areas, in which high reflectivity is desired, for example. Due to particularly intense exposure to the radiation.

In a further preferred embodiment, the front side of the Vorblendelementes is diffusely reflective. This is advantageous for areas of lower radiation exposure, for example, at the inlet or outlet of a drying plant with conveyor. In further embodiments of the irradiation arrangement according to the invention, the rear side of the Vorblendelementes is blackened. As a result, the radiation and thus the heat dissipation to the cooled system parts is designed particularly efficient.

According to the invention, the Vorblendelement is interchangeable attached. This makes it particularly easy to clean dirty areas of the irradiation arrangement. In preferred embodiments of these embodiments, the Vorblendelement is attached by means of a snap connection or clamp connection.

In further advantageous embodiments, the Vorblendelement comprises a plurality of modules, which are each mounted individually. Thus, only those modules need to be replaced, which are actually dirty.

Preferably, the Vorblendelement via a fastening device, designed as a light support structure with wire sections, in particular of spring wire, attached to the wall, wherein the Vorblendelement is profiled for attachment to wire sections. About such a fastening device is only a small heat conduction to the actively cooled system parts out. Thus, the determination of the operating temperature of the Vorblendelements can be done in a simple and predictable way on the determination of the reflection and Abstrahligenschaften.

In preferred embodiments of an irradiation arrangement according to the invention, the Vorblendelement aluminum sheet or one or both sides enameled or coated with ceramic steel sheet. Advantageously, the aluminum sheet can be polished on the front side and / or anodized on the back side. Such Vorblendelemente are chemically and mechanically resistant, heat resistant and according to findings of the inventors for the requirements in the operation of inventive irradiation arrangements generally suitable.

In further, particularly simple and inexpensive embodiments of the invention, the Vorblendelement on a metal foil. This is inexpensive and can be easily attached or replaced, but is not as strong and stable as massive modules.

Fig. 1

in schematischer Darstellung einen Wandungsausschnitt einer erfindungsgemäßen Bestrahlungsanordnung mit einer Befestigungseinrichtung und einem Vorblendelement;

Fig. 2

einen Ausschnitt einer Seitenwandung einer erfindungsgemäßen Bestrahlungsanordnung mit als Seitenreflektor ausgebildetem Vorblendelement;

Fig. 3

der Eingang eines Strahlungstunnels einer erfindungsgemäßen NIR-Bestrahlungsanordnung mit Strahlungsquelle und Vorblendelementen.

Further advantages and advantages of the invention will become apparent from the following description of preferred embodiments with reference to FIGS. From these show:

Fig. 1

a schematic representation of a wall section of an irradiation arrangement according to the invention with a fastening device and a Vorblendelement;

Fig. 2

a detail of a side wall of an irradiation arrangement according to the invention with trained as a side reflector Vorblendelement;

Fig. 3

the entrance of a radiation tunnel of an inventive NIR irradiation arrangement with radiation source and Vorblendelementen.

Fig. 1 shows a section of a wall 11 of an irradiation arrangement 10 according to the invention, to which via a fastening device 12 a (here partially cut shown) module 14-1 of a Vorblendelementes 16 is attached. Another module 14-2 of the Vorblendelementes 16 is attached via a further fastening device, not shown, on the wall 11.

The wall 11 is designed as a solid support structure for the process or radiation space. Channels 18 are used to pass cooling fluid, such as water, air or a thermal oil. The simplest and therefore most cost-effective solution is water cooling with water at low pressure. Should the temperature of the wall 11 are in operation of the system above 100 ° C, however, the cooling by water at high pressure, air or oil is also possible.

The fastening device 12 is designed as a quick-release holder made of spring wire. The wire forms two fixed at a central point frame or legs 20, 22. The connection with the wall is realized as a rivet connection 24.

Varied deviations from the in Fig. 1 shown embodiment of the fastening device 12 are conceivable. Thus, instead of the two frames 20, 22 made of spring wire, only one frame or there may be more than two frames. These may be attached to the wall via two or more connections; instead of over rivets, as in Fig. 1 shown, also screw or other types of connections can be used.

The module 14-1 is clamped onto the spring wire frames 20, 22 of the fastening device 12. It has to advantageous on one side of a receiving portion 26 for the spring wire, so that the module 14-1 can be mounted when mounted in the frame 20, 22. By manual pressure, the attachment of the module 14-1 then takes place on the wall 11. The distance between the back of the module 14-1 and the surface of the wall 11 is approximately 2 to 5 millimeters.

The clamped module 14-1 can either be removed without tools or with a simple tool (eg a screwdriver) with little expenditure of time.

The receiving area 26 is formed by a suitable profiling of the module 14-1 during its manufacture. However, a clamping of the modules is possible even without such a receiving area. Likewise, other profiles are conceivable, for example, lead to a postponement or snapping the modules on the fasteners.

In Fig. 2 For a second embodiment of the invention, a section of a wall 11 'of an irradiation arrangement 10' is shown. The wall 11 'consists of aluminum extruded profiles and is provided with active water cooling. For this purpose, not visible cooling water channels are pressed into the profile. A connection 27 of a cooling water channel is indicated. Openings 28 allow the joining of the wall 11 'with other, not shown portions of the assembly 10'.

A Vorblendelement 16 'is composed of individual modules, of which the modules 14-3 - 14-5 are indicated. Another module has been removed, so that the module facing surface 29 of the wall 11 'can be seen. The surface 29 is blackened (indicated by hatching) and is thus suitable for the efficient absorption and removal of the heat radiation emitted by the rear side of the Vorblendelements 16 '.

Unlike in the Fig. 1 As shown, the fastening device 12 'here consists of four frame sections 20' of spring wire for attachment of each module. In each case two of the frame portions 20 'are mounted on the wall 11' via a double rivet connection 24 '. In the two embodiments it is shown that the shape of the modules can be rectangular or square. Other shapes are also conceivable, with the shape of the modules resulting, inter alia, from the geometry of the radiation space and the desired handling of the modules for each specific application. Differently shaped modules can be combined to form a Vorblendelement.

In Fig. 3 A third exemplary embodiment of an irradiation arrangement 10 "according to the invention is shown, wall sections 11" forming an entrance of a radiation tunnel 30. The wall 11 "is in turn actively cooled, with a connection 27 'serving to supply and discharge cooling water.

The wall sections 11 "of the radiation space 30 are lined with a modularly constructed Vorblendelement 16". Exempted is a bridge or an irradiation area 32, which in the operation of the tunnel 30 by a not formed quartz glass, below which a plurality of NIR emitters 34 which radiate NIR radiation into the tunnel 30.

In operation, irradiation material is passed through the radiation tunnel 30 by means of a conveyor belt, not shown. To avoid touching the tape, some of the modules of the Vorblendelementes 16 ", for example, the modules 14-6, 14-7, each provided with a shock protection 36. This is advantageous instead of attached to the wall on the modules, for example by Screw in to allow quick and easy replacement of these modules as well.

The modules of the Vorblendelementes 16 "may differ in the reflection properties of their front pages, so that the modules assume the desired (high) temperatures during operation., For example, the modules 14-8, 14-9 in Fig. 3 are made of highly reflective aluminum sheet, the intense radiation exposure at the location of the modules 14-8, 14-9 is taken into account, while the modules 14-6, 14-7 of diffuse reflective material, such as enameled steel sheet, to the lower radiation exposure in place modules 14-6, 14-7. By means of the different reflectivities, it is achieved that all modules assume a high temperature in comparison to the cooled wall 11 "and prevent or at least greatly reduce the precipitation of constituents which evaporate or degasify from the irradiation material on the Vorblendelement 16".

In addition to the reflectivity and the radiation capacity of the back of the Vorblendelements can be used by blackening to adjust the temperature. Be fastening devices such as those in the FIGS. 1 and 2 shown, used wire-shaped mounts, the heat conduction through the fastening device with regard to the thermal equilibrium of the Vorblendelements can be neglected (however, a low heat dissipation by convection is always done in addition to the heat radiation).

During operation of the system, therefore, the solvents are not or only to a small extent precipitated on the pre-glazing elements lining the wall, but instead remain in gaseous form inside the radiation room and can be extracted by a ventilation system. Compared to known systems so that the pollution of the reflective system components is substantially reduced. Cleaning work falls in a correspondingly smaller extent.

The treatment still occurring contamination designed beyond much easier, since the soiled modules of the Vorblendelementes not cleaned and polished, but only be replaced. Overall, therefore, the downtime shortened significantly. Removed modules can, however, be cleaned according to the type and degree of contamination, if necessary also outside the plant, and later reused.

An irradiation arrangement according to the invention is advantageously usable, for example, in drying installations for drying and / or curing paints. In this case, a paint coating applied to a substrate is exposed to radiation in the infrared range and / or in the UV range. The reflectivity of the Vorblendelementes of the invention can be adapted to the specific wavelength ranges used, so that the element in the operation of the. Plant assumes a temperature above the boiling point of solvents evaporating from the paint.

An irradiation arrangement according to the invention can furthermore advantageously be used in radiation drying installations for drying paints, printing inks, glazes, oils or the like into substances to be permanently introduced into a substrate. The substrate is exposed to radiation which penetrates into the substrate to a certain depth. This causes a drying or hardening of the introduced substances, whereby solvents can be released from the color and / or constituents of the substrate itself. A lining of the radiation space of such a system with the Vorblendelement invention also leads to a significantly reduced pollution and thus lesser standstill.

A thermal irradiation arrangement according to the invention can furthermore advantageously be used as a heating section or as part of such in a system for stretch blow molding, for example for the production of PET containers from preforms or preforms. In this case, the preforms are heated in a short period of time to a drawing temperature of about 110 ° C and fed in the heated state of a stretch blow mold in which the final shape of the container is formed under the supply of compressed air. For heating, infrared radiators are often used. Counter and side reflectors are used to generate an optimum for the heating of the preform radiation field. If the reflectors are not formed by the wall itself, but by pre-blend elements according to the invention, the advantages described above with respect to drying systems also arise here.

The embodiment of the invention is not limited to these examples and the aspects highlighted above, but within the scope of the claims also in a variety of modifications possible, which are within the scope of professional practice.

LIST OF REFERENCE NUMBERS

10, 10 ', 10 "

irradiation device

11, 11 ', 11 "

wall

12, 12 '

fastening device

14-1 - 14-9

modules

16, 16 ', 16 "

Vorblendelemente

18

Cooling fluid channels

20, 20 ', 22nd

Frame made of spring wire

24, 24 '

riveted joints

26

reception area

27, 27 '

Cooling water connection

28

Openings for joining

29

Surface of the wall

30

radiation tunnel

32

irradiation area

34

NIR emitter

36

contact protection

Claims (11)

1. Thermal radiation arrangement (10, 10', 10") for heating a material to be irradiated, having at least one high-performance radiation source for radiation having an essential active component in the visible and/or IR and/or UV range, in particular in the range of the near infrared (34), and at least one wall (11, 11', 11 ") which is exposed to radiation
   characterized by
   a pre-orifice element (16, 16', 16"), which is fixed to the wall with a distance, having a reflecting front side which is exposed to radiation and an emitting backside which is faced to the wall, wherein the pre-orifice element (16, 16', 16") is exchangeably fixed.
2. Radiation arrangement (10, 10', 10") according to claim 1,
   characterized in that
   the reflection and emission properties of the pre-orifice element (16, 16', 16") are determined such that during operation of the radiation arrangement a temperature above the temperature of the wall (11, 11', 11") is set.
3. Radiation arrangement (10, 10', 10") according to claim 1 or 2,
   characterized in that
   the front side of the pre-orifice element (16, 16', 16") is highly reflecting.
4. Radiation arrangement (10, 10', 10") according to one of the preceding claims,
   characterized in that
   the front side of the pre-orifice element (16, 16', 16") is diffusely reflecting.
5. Radiation arrangement (10, 10', 10") according to one of the preceding claims,
   characterized in that
   the backside of the pre-orifice element (16, 16', 16") is blackened.
6. Radiation arrangement (10, 10', 10") according to claim 1,
   characterized in that
   the pre-orifice element (16, 16', 16") is fixed by means of a snap fit or a clamp connection.
7. Radiation arrangement (10, 10', 10") according to one of the preceding claims,
   characterized in that
   the pre-orifice element (16, 16', 16") comprises a plurality of modules (14-1 up to 14-9), which are individually fixed, respectively.
8. Radiation arrangement (10, 10', 10") according to one of the preceding claims,
   characterized by
   a fixing equipment (12, 12') configured as a light supporting structure having wire sections, in particular made from spring wire, wherein the pre-orifice element (16, 16', 16") is profiled for fixing to wire sections.
9. Radiation arrangement (10, 10', 10") according to one of the preceding claims,
   characterized in that
   the pre-orifice element comprises aluminum sheet or a steel sheet which is enameled on one or both sides or is coated with ceramics.
10. Radiation arrangement (10, 10', 10") according to claim 9,
    characterized in that
    the aluminum sheet is polished at the front side and/or is anodized at the backside.
11. Radiation arrangement (10, 10', 10") according to one of the preceding claims,
    characterized in that
    the pre-orifice element (16, 16', 16") comprises a metal foil.

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