DE10124721A1 - Radiation heating for barostatically operating presses has heat radiation plate from which heat can be transferred to process material by radiation, direct contact heat transfer and convection - Google Patents

Abstract

The radiation heating system has a heating arrangement arranged as a heat radiation plate (1.3) so that a flow of heat can be transferred from it to a process material, e.g. a coated foil, mainly by radiation, direct contact heat transfer and if appropriate by convection. The radiation plate is heated by a heating circuit in which the plate is the load and the heating current can be direct. low frequency a.c. or a higher frequency than the mains.

Description

The invention relates to the exemplary representation of a with heat radiation and direct heat transfer combined working heater for heating of films used in press components, in particular for production of components and elements of the furniture industry.

The purpose of heating devices of this type is the thermal preparation of protective or visible films to be applied primarily to a wooden or Fiber composite materials existing basic body, with the aim of Surface finishing d. H. to create compliments or functionality, with this film is coated.

For this purpose, it is necessary that between the materials to be bonded foil and Basic body introduced a gapless adhesive layer and thermally activated, and procedurally can be handled such that they on the one hand solidify the surfaces of such particle or fiberboard bodies or refine, but also the visual design of these surfaces different tastes or favors of later User can customize. For the latter function in particular, it is crucial that the film is heated so gently that it activates it temperature does not reach its surface damaged or deformed or otherwise changed. This process can be very advantageous with the help of perform quickly and precisely the heat that is applied to the underside Melt the film or the adhesive layer applied to the material to be coated and can plasticize the film. This required heat can e.g. Legs Transfer or deliver radiant heating to the location of your application.

The prior art already knows a number of methods and devices who perform such tasks more or less well. Radiant heaters used exist z. B. from insulated on ceramic or other bodies, on the common electrical networks operated resistance wires or a large number of smaller ones, arranged in groups but also in large areas Tubular radiators in a more or less heat-conducting field are embedded, which usually consists of ceramic. This ceramic field is then in Switching groups or its entirety regulated and appropriately gives its energy z. B. to be melted, to be glued but also otherwise material to be treated or the body to be irradiated. Other types of spotlights also work with wavelengths of visible light and are practically nothing else as powerful often only colored red lamps which are at a certain distance the individual products, radiation zones or one that occurs on these Raktionszone be arranged. Still other technical spotlights work with heated oil, superheated steam; or even with surface burners for oil or gas, each depending on which wavelength of radiation or power is desired or necessary is. Special designs such as B. in temperature-resistant glass bodies or in Pipe continuous or intermittent combustion processes - preferably gas - are also known.  

Such described radiators are such. B. in fillable gas spaces above the mentioned coating films arranged in which a higher pressure - z. B. from some bar - can be built. This pressure then acts on the previous one heated foil, so that it adheres to the resulting force creates the base body and can connect to it by gluing.

The criticism of the technical level starts where the economy and modes of operation conventional radiant heaters disadvantageously diverge. So it is very easy to see that a structure made up of a large number of individual tubular heaters, which are also in their Inside even higher electrical voltages on comparatively thin ones Lead resistance wires, must also be quite susceptible to electrical interference and necessarily also mechanically very sensitive. For radiator fields that usually consist of a plurality of individual ceramic elements always some defective and lamp spotlights have the disadvantage that the individual Lamps also react even more sensitively to mechanical faults is critical in terms of safety due to the mains voltage used. The Known radiant heaters have in common that they all have a much higher one Working temperature level than is required for the actual process. This causes the risk of partial for the process material and the film to be applied or holistic overheating, which causes foil and possibly also that Coating material can be destroyed. There is also one in these heaters significant warm-up time is required until they reach their working temperature. In addition to the possible evacuation times for vacuum presses, this has a major impact essentially the work cycle negative. In addition, falls for the disproportionately long Heating up an energy requirement, with a significant portion of the energy still in the heating phase is lost. The efficiency of such structures is therefore low.

It is therefore the object of the invention to provide a device which electrical process heating of processed goods such. B. wood or Fiber composite materials to be glued films and / or the goods themselves enables without the risk of overheated zones or excessive But having to put up with energy loss works quickly and safely Can be inexpensive and of high quality and turn out to be beneficial usable barometric press rooms and the The surface of the films to be processed is influenced as little as possible or even damaged.

This object is achieved in that the to be glued Foils are tempered by means or devices, on the one hand via a very uniform and adjustable temperature over a large area Can deliver heating power, but also allow that these foils - just as large - for such means or devices for Energy transfer as close as possible to direct contact, without being overheated or destroyed. It is essential that the temperature of these means or devices the working temperature range of the films or their Do not or only slightly exceed the adhesive layer. These facilities or means consist of one or more according to the idea of the invention, usually, however, two electrically conductive, flat elements that are electrically parallel  switched - if necessary completely or partially isolated from each other - each a specific carry comparatively high electrical current and thus through their ohmic Convert heating to a defined electrical output level can. The means or facilities heated by this current flow, e.g. B. Metal sheets, hereinafter referred to as heating plates, partially give off a heat flow by radiation, with direct contact also by heat conduction to the film and / or the material to be processed, which is used to store them on it Working temperature level of e.g. B. bring 100-120 ° C. Of course it is according to the invention also conceivable, these radiant heater panels with conventional Bringing heating elements to the desired temperature, however, dispensed with one thereby on the decisive advantage of the particularly simple and fault-free construction.

In the case of the film, it is necessary to force it into a direct area Bring near and / or in contact with the radiant heater plate. Doing so however, air pockets, folds and damage can be avoided. this will z. B. by reducing the pressure between the film and the radiant heater plate reached, whereby the film through the differential pressure between the top and bottom is applied to the radiant heater plate. In order for this method to be applicable, it is necessary, the air or the gas filling the work area evenly to vacuum or to the space between the film and radiant heater plate displace. For this it is essential to the invention that the radiant heater plate is of such a type is formed that it is gas permeable. Then through the radiant heater plate through which the air or gas is sucked out or displaced through it be what a movement of the film on the radiant heater plate and a Mooring results.

This gas permeability is advantageously achieved in that the radiant heater plate consists of a perforated sheet, which as described by Continuity is heated. Is the surface structure of this perforated plate too large, so that the surface of the plasticized by the action of heat Film is therefore damaged, can be damaged by the application of a porous sub-material with a fine surface structure which is as good as possible should be thermally conductive, the film kept at a distance and a more uniform Force distribution can be achieved. This spacer is particularly advantageous made of a metal gauze, which is also also through direct current passage can be heated. But also other materials such. B. metal profile structures or mesh, metal foam, ceramics, thin materials or plastic structures or - Fabrics can be used with the aim of protecting the surface of the film from deformation protect while transferring heat to them. Isolators will be there passive, conductive materials passively and / or actively heated by current flow. Become in addition to e.g. B. the perforated sheet such spacers such. B. metal gauze uses a composite structure, which the above. Radiant heater plate forms. This the result is uniformly heatable, gas-permeable and finer Surface structure so that the film to be processed is not damaged. A solid body made of metal foam or is also particularly advantageous a comparable material through which electricity flows as a whole and is heated, gas permeable and good heat conduction and a sufficiently fine  and has a homogeneous surface structure. These structures can additionally through suitable measures such as struts and / or attached tubes or profiles can be made mechanically stable. It is also possible that Radiant heater plate in such a way that it is controlled by targeted electrostatic Charging z. B. in spatially delimited charge zones, can be switched on and off by electrostatic influential forces attract the film. It is also fictional essential that z by targeted current flow within the radiant heater plate. B. by applying reinforcements and targeted notches, cuts or Areas of higher or lower hole density of the perforated plate have the temperature profile of the radiator is specifically influenced by areas higher and / or lower electrical resistance are formed, in which correspondingly more or less power is implemented. The high-current source is also claimed such in the construction z. B. to integrate the lid of the press that the Supply routes can be kept correspondingly short, which is the case with the guided high currents is necessary. The further embodiment of the invention also provides that the compensation of such press bodies is disadvantageous at certain points outflowing amounts of heat is possible, which z. B. can be done in that the loss path further heating medium according to the heat flow profile if necessary in Combined with targeted thermal insulation measures.

The structure of the radiant heater plate is particularly in comparison with conventional radiant heaters so simple that they are directly part of the Press construction can be and z. B. in the lid or in a frame can be integrated. Significantly advantageous over z. B. lamp spotlights is the very low working voltage of only a few volts with a high working current, in which such a radiant heater plate is operated. Through this and through that comparatively low temperature, safety in operation is greatly increased. Failures due to the "burning" of the heating element can occur as a result robust structure does not actually occur.

The advantage of the embodiment of a radiant heater for barometric, d. H. presses working with atmospheric negative pressure especially in that instead of a variety of often different, thermal slow, complex arranged in the press chambers and with mains voltage operated radiators of different designs, only one heating structure Is used in the form of a gas-permeable flat component nevertheless be operated on a completely harmless electrical voltage can. Due to the direct heating and the comparatively low mass, the thermal time constant of the radiant heater plate is very small, so that high cycle times and only low waste heat losses can be realized. The radiant heater plate is mechanically insensitive to damage and deformation. such Components can be used equally for different applications only own a few parts and represent systems that work with conventional ones electric radiators are not accessible.

As can be seen in Fig. 1, the heating device according to the invention is z. B. preferably from a machine part such. B. cover, frame, hood o. A. and from the actual radiant heater plate whose detailed structure is shown in Fig. 2. In the selected example, a press or chamber cover which consists of the components, the longitudinal tube profiles 1.1 , the end plate 1.2 and 1.4 and the side walls 1.5 comprises the radiant heater plate 1.3 . The end plates 1.2 and 1.4 are perforated so that the welds 1.6 can be applied. The structure becomes very stiff in this way and a very good return conductor is created which in this way is guided through the chamber cover 1.3 with little loss through the chamber lid and does work.

Fig. 2 shows the actual radiant heater plate, which consists essentially of 5 elements. One recognizes a normal perforated plate 2.1 in which the major part of the electrical energy is converted into heat and a fine metal gauze 2.2 which is connected in parallel with the perforated plate and thus also energized and directly heated. In operation, it rests on perforated plate 2.1 . The frame 2.3 holds the network together and can also serve as a power connection for the high current. An insulating layer 2.4 electrically separates the structure from the infrared reflector 2.5, which may also carry further thermal and electrical insulating layers and which deflects the upward, otherwise useless radiation.

Claims (10)

1. Radiant heating for barostatic presses, characterized in that heating means are provided and arranged as a radiant heater plate so that a heat flow mainly from radiation, direct contact heat transfer and, if necessary, convection to a work piece z. B. a coated film can be transferred. 2. Radiant heating for barostatic presses according to claim 1 characterized in that the heating of the Radiant heater plate is carried out by a heating circuit in which the heating heater plate is the consumer, the heating current being direct current or Mains frequency alternating current or alternating current of another z. B. higher Frequency can be as network frequency. 3. Radiant heating for barostatic presses according to claim 1 or 2 characterized in that the required in the heating circuit high electrical current from transformers, preferably from air gaps Toroidal transformers are induced in single or multi-phase technology. 4. Radiant heating for barostatic presses after one or several of the above claims characterized in that the heat radiating Radiant heater plate made of at least one element made of electrically conductive Material such as B. SiC, but especially made of metal such. B. stainless steel, iron, Titanium, aluminum, copper, brass or a metallic alloy. 5. Radiant heating for barostatic presses after one or several of the above claims characterized in that the strengths, training and Structure of the radiant heater panels by sheets, grids, braids, fabrics, Expanded metal, perforated sheets, metal foam bodies, profiles and / or any Combinations of these are formed so that the radiant panels are individually or are electrically and thermally conductive and gas-permeable as a composite. 6. Radiant heating for barostatic presses after one or several of the above claims characterized in that the radiant heater plate from a superimposed composite of at least one perforated sheet and one metallic gauze. 7. Radiant heating for barostatic presses after one or several of the above claims characterized in that components of the press such. B. the cover the electrical feeder of the radiant heater plate in the heater form a circuit.   8. Radiant heating for barostatic presses after one or several of the above claims characterized in that facilities at the Radiant heater plate are provided the z. B. pneumatic or electrostatic enable or support the application of the film to be heated. 9. Radiant heating for barostatic presses after one or several of the above claims characterized in that the contours of the radiant heater plate and the guidance of the film can be adjusted to the material to be coated. 10. Radiant heating for barostatic presses after one or several of the above claims according to one or more of the above Expectations characterized in that a surface coating of the Radiant heater plate z. B. from Teflon this insensitive z. B. against sticking the film makes the surface emissivity as high as possible is achieved.