EP2296832A1

EP2296832A1 - Press device and method for removing deposits on a press tool

Info

Publication number: EP2296832A1
Application number: EP09749885A
Authority: EP
Inventors: Ralf Niederer
Original assignee: Fritz Egger GmbH and Co OG
Current assignee: Fritz Egger GmbH and Co OG
Priority date: 2008-05-23
Filing date: 2009-05-20
Publication date: 2011-03-23
Anticipated expiration: 2029-05-20
Also published as: WO2009141395A1; DE102008024799B4; DE102008024799A1; ES2397066T3; EP2296832B1; PL2296832T3; PT2296832E

Abstract

The invention relates to a method for removing deposits on a work surface of a press tool (2,3,21,22), in particular for producing a work piece in the form of a wood material plate, a coated wood material plate (9,23,26) and/or a laminate. In order to reliably and cost-effectively remove deposits in the form of residue on a press tool, it is provided that the work surface is irradiated by a laser beam (18) produced by a laser system (16,17,27) and that deposits adhering to the work surface are removed by the laser beam (18).

Description

Pressing device and method for removing deposits on a pressing tool

The invention relates to a method for removing deposits on a working surface of a pressing tool, in particular for producing a workpiece in the form of a wood-based panel, a coated wood-based panel and / or a laminate. In addition, the invention relates to a pressing device for producing a workpiece, in particular in the form of a wood-based panel, a coated wood-based panel and / or a

Laminate, with at least one pressing tool for pressing the workpiece, wherein the at least one pressing tool has a workpiece coming into contact with the workpiece during pressing.

There are already a variety of methods for pressing a workpiece known. Some of the workpieces may give off material to the pressing tool during pressing, which accumulates on the pressing tool, so that from time to time cleaning of the pressing tool is required.

A corresponding method is the production of wood-based panels, in which, for example, wood-based material particles, such as chips or fibers are provided with an adhesive or glued. The

Wood-based material particles are first layered and then pressed at elevated temperature to a wood-based panel. There are also known wood-based panels that glued instead of glued Wood particles are formed by a mixture of at least one wood material and at least one plastic, in particular a thermoplastic material. This is also referred to as Wood Plastic Composite (WPC).

Comparable with the production of wood-based panels is the production of moldings from wood-based materials. These usually consist of the same materials as wood-based panels, but have profiled surfaces. By shaped bodies is meant three-dimensionally shaped elements, which consequently have a profiled surface. The moldings include in particular so-called Doorskins or door decks, which are used for the production of door leaves and represent flat elements with three-dimensionally deformed or profiled area. Large areas of doorskins or door decks, hereinafter referred to collectively as doorskins, have flat surfaces followed by areas that are not in the same plane in extent.

In the production of corresponding moldings, a so-called prepreg is typically first prepared in the form of a pre-consolidated, inherently stable plate. For this purpose, chips, fibers or the like are usually provided with binder and additives in analogy to the production process for plane wood-based panels, dried, formed into a mat and fed to a press. Under the influence of pressure and temperature, the binder should be cured to the extent that the prepreg is stable enough for further processing. As a binder, in principle, all adhesives can be used. Particularly suitable are aminoplasts, such as urea-formaldehyde resins (UF) and melamine-formaldehyde resins (MF), or a mixture of the two. Phenoplasts, such as phenol-formaldehyde resin, are also suitable, as well as a mixture with aminoplasts.

For the compression of a shaped mat for producing a prepreg or a flat wood-based panel are suitable for continuous production press devices with press belts in the arrangement of a double belt press, for example by the conti-roll method or by the calendering or Mendeverfahren, in which rolls as pressing tools or calender rolls are used. In the case of a Kalanderpressvorrichtung usually a plurality of rollers is provided which form with each other nips through which the molded mat is carried out until the desired degree of cure is achieved. The cooperating calender rolls regularly have widely differing diameters. For the discontinuous production in particular one or more days presses with pressing plates come into question.

Subsequently, the prepreg is pressed for final shaping in a pressing device whose heated

Pressing molds opposite pressing plates in the form of moldings form a shape which is adapted in its design to the desired shape in terms of geometry and thickness of the shaped body to be produced. The working surfaces of corresponding pressing tools therefore also have profiled working surfaces. For this reason, the work surfaces often have very tight radii and edged Heels that are easily soiled and hard to clean.

The production of a coated wood-based panel can basically be done in two different ways.

On the one hand, at least one previously impregnated with a resin paper can be applied to a wood-based panel, wherein then the wood-based panel and the at least one resin-impregnated paper are pressed together at elevated temperature. One speaks in this

Context of a direct coating. On the other hand, however, first of all a series of resin-impregnated papers can be pressed together at elevated temperature to form a so-called laminate. Only in a later process then the laminate as a coating on a

Applied wood-based panel and pressed with this. In contrast to the direct coating, in the case of coating by means of laminates, the production of the laminates and the actual coating of the wood-based panel are carried out independently of one another.

In alternative processes for the production of coated wood-based panels, coatings are used which are cured, for example chemically or by irradiation. A pressing process is dispensable in these processes, which are not considered below.

For impregnating or impregnating papers in the direct coating, as well as in the separate production of laminates mainly resins such

Condensation resins used. The curing of these resins takes place on the one hand at elevated pressure and on the other hand elevated temperature in a cycle or a continuous process. In the production of laminates in this context, one speaks of either HPL (high pressure laminate) or CPL (continuous pressure laminate), depending on whether the pressing is continuous or intermittent.

Pressing plates are used for cycle processes, whereas for continuous processes press belts are used, for example, in so-called double belt presses. These press tools have, in particular for the production of laminates and coated wood-based panels, usually a flat surface in order to simultaneously smooth the surface of the workpiece during pressing.

The construction of compact panels, which are typically used in the furniture industry, is comparable or even identical to the construction of laminates. Laminates, like laminates, generally have several layers of resin-impregnated pulp and / or paper webs laid one on top of the other and pressed at elevated temperature into a common workpiece. Also, in both cases, in particular condensation resins are used as impregnation of the pulp and / or paper webs. Compact panels, unlike laminates, are not permanently pressed with a substrate such as a wood-based panel after their manufacture. The resin of the compact panels is completely cured during the pressing, so that the compact panel then retains the form taken during the pressing. For the production of compact panels, therefore, presses with pressing tools designed as molded parts are used as needed, the profile of the Work surface of the molded parts dictates the shape of the later compact panel.

Even with laminating systems for film coating, it is possible for substances to escape either from the film or from the substrate to be coated with the film, which leads to creeping contamination of the pressing tools. In corresponding laminating machines, rolls are predominantly used as pressing tools which form a nip through which the substrate and the film are passed one above the other. The rollers are heated to cure an adhesive and usually have a polished working surface to ensure a flat surface of the laminated film.

Press tools are also understood to mean tools for chipless smoothing of wood-based panels. When smoothing the wood-based panels they are already finished pressed and hardened in itself. The smoothing is therefore only the surface finishing by plasticizing and flattening from the surface of protruding wood fibers or shavings. For this purpose, in particular pressing tools in the form of rolls or press plates are used. The pressing tools are heated, preferably to more than 100 ⁰ C, and must have a very smooth surface, so that deposits that are formed by residues of the wood-based panels on the pressing tools are highly undesirable.

The above-mentioned method and the above-mentioned pressing device can also be used in the production of almost arbitrarily shaped, possibly small-particle moldings used under the action of temperature and pressure be pressed to obtain the desired spatial shape of the moldings. These methods or devices serve in particular the processing of mixtures of at least one wood material and at least one plastic. In particular thermoplastics are used as plastic. On the use of plastics can be waived in the corresponding methods and devices but also. It is essential that when pressing the moldings to residues and thus deposits on the working surfaces of the pressing tools, which lead to undesirable effects.

In the methods and pressing devices described above, depending on the workpiece, residues of, for example, adhesives and / or resins remain adhered to the pressing tool. In addition, it comes in the production of wood-based panels and coated wood-based panels in the pressing process outgassing of the wood material, which precipitate on the pressing tool, possibly connect with the residues and ultimately lead to deposits on the press tool used.

The deposits formed by the residues on the pressing tools accumulate over time and form an increasingly thicker and usually uneven layer on the

Press tools. The deposits hinder the heat transport from the pressing tool to the coating with increasing layer thickness in heated pressing tools, which is why either the hardening of the workpieces can be incomplete or must be pressed longer. In addition, resulting from the resulting as a result of deposits unevenness of the pressing tool Restrictions on the smoothness and gloss of the surfaces to be produced.

Therefore, the deposits on the pressing tools must be removed from time to time. The pressing tools can be cleaned manually, for example, by means of certain cleaning agents, which is labor-intensive and time-consuming and thus causes high costs. In addition, there is a mechanical stress on the surface, which leads to reduced service life of the pressing tools. An alternative method of cleaning the pressing tools is to press them with a special foil to which the deposits partly adhere. The efficiency of this cleaning method is low. In addition, brush rollers or bristle belts are used to remove the deposits on the pressing tools, which in turn leads to increased wear of the pressing tools and a reduction in the gloss level of the surface of the pressed coating.

EP 1 080 798 A2 describes an apparatus and a method for removing resin residues from metallic press plates by means of water jets, which are conducted under high pressure onto the press plates. This requires a complex treatment of the used process water again.

The present invention is therefore based on the technical problem of proposing a method and a pressing device of the type mentioned, with which deposits on a pressing tool can be removed reliably and inexpensively, without resulting in increased wear of the pressing tool. This technical problem is solved in a method according to claim 1, wherein the working surface is irradiated with a laser beam generated by a laser system and in which adhering to the working surface deposits are removed by the laser beam.

In addition, the mentioned technical problem is solved in a pressing device according to claim 12, characterized in that a laser system is provided, that the laser system is adapted to irradiate the working surface with a laser beam and that the laser system for delivering a for ablating adhering to the working surface Deposits suitable laser beam is formed.

The invention is therefore based on the idea that the press plates can be specifically cleaned by laser beams, which can be selectively introduced into the deposits by the laser radiation energy so that the deposits evaporate and thus also possibly lead to a chipping of adjacent deposits. In addition, it has been recognized that damage to the pressing tools can be avoided, which is why no or only a very minimal wear on the pressing tools through the use of the laser system must be taken into account. In addition, a liquid detergent and its handling can be saved, which also prevents contamination of the working environment.

According to the invention, the method can be independent of the

Pressing the workpiece to be performed, with the pressing tools to be cleaned, for example, be removed and a separate cleaning device for performing the method described. The actual pressing device can then be used with other pressing tools or stand still when the pressing device is not needed during the cleaning of the pressing tools. The method can thus be operated alongside or independently of the production process. This allows a high flexibility.

The deposits may either be residues of an adhesive used or a component of the coating used, preferably a resin such as a condensation resin. In addition or as an alternative, the deposits may have outgassings of the pressed workpiece. This is especially true in the

Compressing a wood-based panel or a coated wood-based panel into consideration, the outgassing then preferably ingredients of the wood material used are. In the end, the deposits are in any case formed in part by residues of a coating or impregnation, which are preferably residues of a resin, residues of an adhesive, outgassing of either the wood material, the coating, the impregnation or the adhesive and / or reaction products of the aforementioned components.

The device is provided to perform the cleaning of the pressing tools in the pressing device. An expansion of the pressing tools is then not required. If desired, the removal of the deposits can also be carried out during the operation of the pressing device become. This can be done when / where the work surface is not in contact with the workpiece.

The laser system is provided such that it allows the irradiation of a certain area of the working surface with the laser beam generated by the laser system. The energy of the laser beam is absorbed by the deposits, which leads to their removal. Preferably, there is a spontaneous, locally limited heating and finally to an evaporation of the deposits. If necessary, non-vaporized, adjacent deposits simultaneously burst from the working surface.

In a first embodiment of the method can be provided according to the inventive device that the method is also provided for producing a workpiece, in particular in the form of a wood-based panel, a coated wood-based panel, a laminate and / or a compact board, wherein the workpiece in a pressing device with at least one

Crimping tool is pressed, wherein the working surface of the pressing tool is brought into contact with the workpiece during the pressing and wherein the working surface is irradiated in the pressing device with the laser beam generated by the laser system. Under a pressing in this context, a smoothing of the workpiece surface is understood in which a considerable pressure on the workpiece can be exercised.

The removal of the deposits on the pressing tools in the pressing device has the advantage that an expansion of the pressing tools are omitted and thus unnecessary Plant shutdown can be avoided. This also makes automated operation possible.

By removal of deposits in the installed state, such as during a continuous operation, the

Pressing tool, in particular during pressing of the coated wood-based panel over a long time a certain smoothness of the working surface of the pressing tool and thus, if necessary, a predetermined gloss level of a coating can be maintained. Ultimately, the service life of the pressing tool can be increased in this way. In addition, the removal of the deposits with the laser beam of the laser system leads at best to a minimal impairment of the working surface, so that far longer service life of the pressing tool can be achieved without restrictions, for example, with regard to the gloss level of the coated wood-based panel or their coating are accepted would.

Hereinafter, the advantageous embodiments of the method and the pressing apparatus will be described together without distinguishing in detail between the method and / or the pressing apparatus, thereby avoiding unnecessary repetition. The specific embodiments relating to the method and / or the pressing device will be apparent to those skilled in the art from the context of the following description.

In one embodiment of the invention it is provided that glued chips and / or fibers are first layered and then the layer of chips or fibers are pressed into a wood-based panel. Depending on the used For example, this layer of chips and / or fibers is pressed into chipboard, Oriented Strand Boards (OSB) or medium density fiberboard (MDF) and high density fiberboard (HDF). All these wood-based panels are suitable because of their mechanical properties, for example, for the furniture or flooring production. When pressing the adhesive or glue cures, so that a stable wood-based panel is obtained. The deposits consist predominantly but not necessarily outgassing of the

Wood material and residues of the adhesive. These are then removed in the pressing device or in the expanded state of the pressing tools by the laser beam. As a result, the production of high-quality particleboard or fiberboard ultimately cost possible.

Alternatively or additionally, a mixture of at least one wood material and at least one plastic for the production of wood-based panels, ie in this case WPC boards (Wood Plastic Composite), are used, which offer in particular thermoplastics due to the good processability at high temperatures. As wood-based materials, wood chips and / or wood fibers come into question in particular because of the good mechanical properties. It can also be made of a mixture of at least one plastic material and at least one other lignocellulose-containing material than wood, such as straw. Also in this case can be obtained efficiently and inexpensively Holzwerstoffplatten or material plates in high quality by compression. This advantage is achieved to a particular extent in the production of moldings, in particular in the production of Doorskins. These can be made from the same materials. For the production of Doorskins but formed as a molded part pressing tools are required, which have a profile that corresponds to the profile of the Doorskin to be produced. Due to the profiling of the pressing tools, residues are increasingly formed on the surfaces of the workpieces, which are also difficult to remove due to the profiling. In addition, unevenness arising during pressing can no longer be eliminated by a grinding process, as in the case of flat wood-based panels, since this would lead to a change in the profile geometry.

In an alternative embodiment of the invention, a preferably already finished wood-based panel, preferably in the form of a chipboard or fiberboard, is coated by compression with a coating. It is therefore produced a coated wood-based panel, the deposits adhesive residues, residues of the coating, outgassing about the wood material and / or reaction products of said components may have, which are then removed by the laser beam either installed in the pressing device or dismantled in the state. Consequently, if necessary, coated wood-based panels can be produced inexpensively with a high surface quality. This is especially important for coated wood-based panels for furniture production. As a coating, an impregnated paper or a plurality of laminated impregnated papers may be used for a direct coating. The least an impregnated paper is not or only slightly cured before coating. The curing is essentially initiated by the pressing. A direct coating can thus be used, for example, at low cost and at the same time high quality in furniture or floor panel production.

Alternatively or additionally, a laminate which consists of at least one layer of an impregnated paper can also be used as the coating of the wood-based panel. In principle, any number of layers of impregnated papers in which, for the sake of simplicity, no distinction is made between papers, fabrics or nonwovens may be combined to form a laminate. The laminate as such is preferably already pressed and thus in any case precured. The laminate may, for example, a decorative paper and, if necessary, another

Have overlay paper to protect the decor paper. Thus, wood-based panels can be coated cost-effectively and with high quality with laminates, for example for the production of floor panels.

If necessary, the wood-based panel or other substrate is coated with a film, which is commonly referred to as laminating. In this case, the pressing device is designed for pressing the film, which can form residues during pressing and / or on the

Substrate on which the film is laminated is returned residues up to the working surface of the pressing tool reach. The application or lamination of a film is preferably carried out with rollers forming a nip.

In a further embodiment of the invention it is provided that at least two impregnated papers are pressed into a laminate. The laminate comprises predominantly at least one core layer and a decorative layer. Each of these layers may be formed by an impregnated, compressed paper, wherein the impregnation for a core layer preferably comprises a phenolic resin and the impregnation for a decorative layer preferably comprises a melamine resin. Even in the production of laminates, the advantages of the method and the pressing device can be used.

In particular, significantly longer service lives are achieved, since the materials used tend to form residues, so that the thickness of the resulting deposits increases rapidly.

A coated wood-based panel can also be produced by compression with a laminate. Since the laminate only fully hardens, deposits are produced on the working surfaces of the pressing tools, which can be easily removed by means of a laser beam.

Also in the production of compact panels are impregnated without using a wood material impregnated pulp webs and / or papers, which may be decorative paper in part, pressed together. Again, the use of a laser beam to remove deposits particularly effective because the materials of preparation are similar or equal to those for the manufacture of laminates, and highly prone to the formation of residues. In addition, very high demands are placed on the surfaces of compact panels, so that the use of a laser steel is well suited to always provide a relatively clean and flat Ärbeitsoberflache, which also ensures high gloss levels of the surface of the workpiece after compression.

The impregnation for the papers and / or pulp webs and thus possibly for the coating itself preferably has a condensation resin. Due to their mechanical and chemical properties, preference is given in particular to urea resins (UF), melamine resins (MF) and / or phenol resins (PF). In principle, however, other resins are also conceivable which cure at elevated pressure and optionally additionally at elevated temperature. These resins are difficult to remove by conventional methods because of high adhesion forces. The impregnations mentioned are particularly preferably used in the production of coated wood-based panels, laminates and compact panels.

The removal of deposits by means of a laser beam can also be used advantageously in processes for the production of non-plate-shaped moldings, which are not Doorskins, since the disadvantages caused by the deposits can be considerably reduced. In particular, here comes the production of arbitrarily shaped, preferably highly profiled moldings into consideration, since the working surfaces used for this purpose of the pressing tools easily soiled and then unable to produce the desired profile. The advantage of the removal of deposits with a laser beam is even greater if, in contrast to wood-based panels, it is a small-scale molded body, the production of which requires a particularly high quality on a regular basis.

The positive impact on the quality and cost of manufacturing achieved by the removal of deposits on the work surfaces is also enormous in chipless smoothing of wood-based surfaces. Pressing tools for smoothing surfaces of wood-based materials must themselves be very smooth, so that the damage of the working surface, which has hitherto hardly been avoidable when removing deposits, is only very short

Service life of the pressing tools have allowed. Although smoothing of the surface of a workpiece may be considered essentially as surface processing, smoothing of the surface of a workpiece still constitutes a method of manufacturing a workpiece according to the invention, namely the production of a smoothed workpiece.

The removal of deposits of a working surface of a pressing tool in the form of a roll, a press plate, a press belt, in particular a double-belt press, and / or a molded part is particularly effective to perform. Deposits of press belts and rolls can be easily removed during their continuous operation with a laser beam, since usually a part of the surface for the laser beam is easily accessible. In the case of press plates in cyclic operation, deposits can be made in cycles with the laser beam be removed, since there are no other media introduced into the press nip. In addition, press plates can be removed more easily and, with only a short downtime of the press device effectively free from deposits with a laser beam. In the case of molded parts, there is a particular advantage in that areas of the working surface with narrow radii, ie strongly curved areas, can be achieved with the laser beam, so that effective removal of deposits is possible there.

Moreover, it is preferred if the pressing tool used has a metallic, a heatable and / or a structured working surface. On heated work surfaces there is a rapid hardening of the residues or deposits, so that removal was previously difficult. The removal of structured work surfaces can be done much better with the laser beam than with other methods, since it can penetrate into very small structures without destroying these structures. The same applies to profiled

Working surfaces of pressing tools in the form of shaped bodies, as here too often narrow, hard to reach areas with narrow curvatures or edges are present.

The laser system is characterized by another

Configuration of the pressing device and the method by the emission of pulsed laser beams. The energy of the laser radiation is selectively released in individual short pulses, so that a spontaneous local evaporation of deposits is ensured. The laser system is preferably designed such that the pulse lengths of the laser radiation less than 1 microseconds, more preferably some a few ns (10 ^{~ 9} s). Because of the short exposure times of the individual pulses, there is overall only a small heat input and no large-scale heating of the pressing tool.

Good results with regard to the removal of deposits were achieved with laser powers of the laser system of 80 to 120 watts, in particular of about 100 watts.

Preferably, laser beams having wavelengths predominantly absorbed by the deposits are used. Thus, it is possible to use the majority of the radiation energy, it being particularly expedient for the laser radiation to be absorbed essentially completely by the deposits due to its wavelength.

In order to minimize the wear of the pressing tool, the wavelength of the laser beams is alternatively or additionally chosen so that they are predominantly reflected by the working surface of the pressing tool. The majority of the radiation energy is radiated directly in this way again, without the radiant energy can lead to heating or even damage to the work surface. It is particularly appropriate in this context if the laser radiation as a result of the wavelength is substantially completely reflected by the working surface. Then the

Radiation intensity can be increased or remain the radiation directed to the work surface longer, without causing any local damage to the working surface. It is particularly preferred in this context if the working surface is made of a metallic material, so that a high degree of reflection of the laser radiation can be achieved.

The press tool used in each case can be freed of deposits in the removed state. But it can also be done a cleaning in the installed state. In particular, when using press tools in the form of rolls such as a calender press or press belts a

Double belt presses that are operated continuously, the deposits can also be removed continuously during operation. This is efficient and economical because a regular expansion of the pressing tools can be prevented.

For cyclically operating pressing tools this is not readily possible because of usually short cycle times, so that the removal of deposits between two cycles can at least be done in the manner of partial cleaning of the work surface. If different sections of the work surface are cleaned between individual cycles, a guasic continuous cleaning of the entire working surface is still possible.

This is basically possible in two different ways. On the one hand, the laser system may be stationary provided on the pressing device. This means that the laser system as such does not move during operation. The laser system is merely tilted, tilted, or otherwise sequentially applied to different areas of the work surface of the laser Pressing tool directed so that the work surface can be cleaned in total. This solution is structurally simple.

On the other hand, however, the laser system can also be moved during operation of the pressing device as such relative to the pressing device and / or relative to the pressing tool. In particular, the laser system moves back and forth in the vicinity of the pressing space. In a clocked pressing device, this movement is matched with the cycle of the pressing tool. Thus, the press plate is then preferably at least partially freed of deposits between two cycles by means of the laser beam, wherein different sections of the working surface can be irradiated with different laser beams between different clocks.

It is particularly preferred in this case if the laser system is mounted on a device such as a carriage, a tray or a carriage, wherein the device is in any case moved back and forth in a coordinated manner with respect to the pressing chamber in relation to the cycle of the pressing device. This can be the case in particular for transporting the workpieces into and out of the press room. Corresponding devices are already known from the pressing devices of the prior art, so that need not be further discussed here. It may be, for example, so-called feed tablet, suction car or the like.

The pressing space of the clocked pressing device is predominantly the space between two interacting press plates. In principle, however, it is sufficient if at least one press plate is provided. If two press plates are provided, preferably both sides of the wood-based material board are coated in the production of coated wood-based panels. It can both

Press plates or even a press plate for closing the pressing space to be movably mounted.

The pressing tool can also be a press belt if a continuous process is to be provided. The press belt may preferably be a belt of a double belt press. When using a double belt press, the press belts are arranged parallel to each other and include a press nip between each other. This allows, for example, a two-sided coating of a wood-based panel with high quality. In the case of floor panels can be provided in this way without further simultaneously with a decorative layer a Gegenzugschicht on the opposite side of the wood-based panel. In addition, the use of a press belt makes it possible in general to direct the laser beam onto a run of the press belt, with the press belt then moving independently relative to the laser beam without the laser system having to be moved. Thus, in any case, the deposits can be removed via a strip of the press belt. To machine the entire width of the press belt, a laser system can be used whose laser beam can irradiate the entire width of the press plate. Alternatively, several laser systems can be provided side by side. Preferably, however, the laser beam of a laser system is moved stepwise or continuously perpendicular to the direction of movement of the strand, ie transverse to the strand. It is understood that preferably the press belt is acted upon at a location with the laser beam at which the press belt is not in contact with the workpiece. If necessary, the laser beam hits the press belt in the inlet area or in the outlet area.

Regardless of the type of pressing tool, the laser system can be moved back and forth in a plane parallel to the section of the pressing tool to be machined and / or the run of the pressing belt to be processed. Thus, all sections of the working surface, including large press plates and / or wider press belts, can be successively freed of deposits. In this case, the movement of the laser system can take place longitudinally and / or transversely to the respective pressing tool or the working surface to be machined, that is to say either in one or in two spatial directions.

In order for a favorable process to be achieved both with regard to the hardening of the workpiece in the pressing device and with regard to the removal of deposits, the pressing tool can be heated. This does not lead to problems when cleaning the working surface, since the cleaning with a laser steel can be carried out without contact.

Incidentally, it has been found that pressing tools with a structured working surface can also be used in the method and in the pressing device. The working surface of these pressing tools is not completely flat, but has a structure that transfers to the workpiece during pressing. This is especially true when pressing coated wood-based panels of Meaning, in order to achieve a good look of the surface in this way. For the furniture industry and for floor coverings wood decors are mostly used. One also speaks of such structured surfaces of wood pores, as they also occur in natural wood. Of course, the same applies to other decors, such as stone or ceramic decors.

Also, a profiled work surface of pressing tools in the form of molded parts that have a pronounced spatial

Profile may additionally be structured with. Since appropriate work surfaces for residues and deposits provide a particularly good grip, here a material-friendly and reliable removal of deposits is particularly preferred.

The invention will be explained in more detail with reference to a drawing illustrating only embodiments. In the drawing shows

Fig. 1 shows a first embodiment of the pressing device according to the invention in one

Side View,

1 in a section according to the plane II-II of Fig. 1,

3 shows a second embodiment of the pressing device according to the invention in a side view with opening press plates, Fig. 4, the pressing device of FIG. 3 with open press plates and

Fig. 5, the pressing device of FIG. 3 with closing press plates.

1 and 2, a pressing device 1 in the form of a double belt press is shown schematically, in which two press belts 2,3 are endlessly guided around each two pulleys 4,5. The pressing belts 2, 3 are arranged parallel to one another, with the mutually facing trunks 6, 7 of the two pressing belts 2, 3 having parallel transport directions and defining a gap 8 which is slightly narrower than the wood-based panels 9 together with the coatings 10, 11 before the pressing , The

Wood-based panels 9 together with the coatings 10,11 run from the side shown on the right into the pressing device 1 are detected by the press belts 2,3, transported by the pressing device 1 and discharged on the left side, the coatings 10,11 when it expires are substantially cured from the pressing device 1.

For the sake of better clarity, in FIGS. 1 and 2 the gap 8 and the wood-based panel 9 are enlarged relative to the press belts 2, 3.

In the illustrated preferred embodiment, in the pressing device 1 on both sides of the wood-based panel 9 is a separate coating

10, 11, wherein the coatings 10, 11 may be impregnated papers or laminates. Between the two pulleys 4, 5 of each press belt 2, 3, there are provided for the gap 8 assigned means 12, 13 for providing and equalizing the contact pressure, each of which acts on a run 6 assigned to the gap 8. The respective other run 14, 15 of each press belt 2, 3 is assigned a laser system 16, 17 in a manner such that a pulsed laser beam 18 strikes a part of the work surface between the two guide rollers 2, 3. The pulsed laser radiation 18 is in any case partially absorbed by the deposits adhering to the press belt 2, whereby the absorbed laser radiation converts almost directly into thermal energy, so that the deposits spontaneously evaporate in locally limited areas as a result. If the laser radiation hits directly on the work surface, it will be reflected so much that no damage to the working surface will occur.

In the illustrated and so far preferred

Embodiment, the laser systems 16,17 are moved back and forth transversely to the transport direction of the press belts 2,3, so that gradually all areas of the working surface are irradiated with the laser radiation 18 and cleaned so. If such a cleaning cycle is completed, this is followed by another cleaning cycle, as deposits are formed continuously during continuous process control.

Moving the laser systems 16,17 across to

Transport direction of the respective press belt is 2.3 illustrated in particular in FIG. 2, which shows the double belt press from a front view.

FIG. 3 schematically shows a discontinuously operating pressing device 20. The pressing device 20 has two pressing plates 21, 22 which are adjustable relative to each other. The press plates 21,22 move apart in the operating state of the pressing device 20 shown in FIG. 3, while the last pressed workpiece in the form of a coated

Wood material board 23 is still in a press room 24 between the two press plates 21,22. Partially inserted into the baling chamber 24 is a device 25, which grips the last pressed and thus coated wood-based panel 23. The following to be pressed

Wood material panel 26 has already been taken together with the coating not shown in detail and is moved in this way in the direction of the pressing space 24. Since the coating is not yet firmly connected to the still to be pressed wood material panel 26, the still to be pressed wood-based panel 26 is preferably held laterally. On the device 25, a laser system 27 is mounted, which is also moved in the direction of the pressing space 24.

A short time later in the same cycle, the device 25, as shown in Fig. 4, moved further to the left and are the last pressed, coated wood-based panel 23 outside of the pressing chamber 24 free. During this time, shortly before or shortly after, the wood-based panel 26 to be subsequently pressed, together with the coating, will also become released from the device 25, in the press room 24 between the press plates 21,22.

At the same time, the laser system 27 is retracted into the pressing chamber 24 and has there already at least one of

Press plates 21,22 at least partially freed when passing through the pressing chamber 24 of deposits. If the laser system 27 is mounted outside the wood-based panels 23, 26, the laser unit 27 can theoretically direct a laser beam onto the upper press panel 21 and a further laser beam onto the lower press panel 22. This can be done simultaneously or at different times. For example, in one cycle, the laser beam may be directed to the upper press plate 21 and, in a subsequent cycle, to the lower press plate 22. As an alternative, however, other laser systems may also be provided.

As shown in Fig. 5, the device 25 is moved together with the laser system 27 after the separation of the wood-based panels 23,26 to the right from the press room 24 to a new, still to be pressed

To take wood-based panel and bring in the next cycle in the press room 24. Since the laser system 27 reciprocates at each cycle, each time different areas of the working surface of the at least one press plate 21, 22 can be cleared of deposits. When the laser beam has reached each area of the working surface of the at least one pressing plate 21, 22, it is again brought into an initial position, after which the cleaning begins again. Also in this context it can be provided that the laser system 27, so that each area of the work surface can be easily reached, is arranged perpendicular to the direction of movement of the device 25 on this.

Claims

claims

1. A method for removing deposits on a working surface of a pressing tool (2,3,21,22) for producing a workpiece, in particular in the form of a wood-based panel, a coated

Wood-based panel (9, 23, 26), a laminate and / or a compact panel, in which the working surface is irradiated with a laser beam (18) generated by a laser system (16, 17, 27) and deposits adhering to the working surface through the panel Laser beam (18) are removed.

2. The method of claim 1, - in which the workpiece (9,23,26) is pressed in a pressing device (1,20) with at least one pressing tool (2,3,21,22), wherein the working surface of the pressing tool ( 2, 3, 21, 22) is brought into contact with the workpiece (9, 23, 26) during pressing, in which the working surface in the pressing device is irradiated with the laser beam (18) generated by the laser system (16, 17, 27) ,

3. The method of claim 1 or 2, wherein the glued chips, glued fibers and / or mixtures comprising at least one wood material and at least one plastic to a wood-based panel (9,23,26), preferably chipboard, OSB board or fiberboard, in particular medium density Fiber board (MDF) or high-density fibreboard (HDF) or a Doorskin be pressed.

4. The method according to any one of claims 1 to 3, wherein a wood-based panel (9,23,26) by

Pressing with a coating (10,11), preferably in the form of at least one film, an impregnated paper, in particular decorative paper and / or overlay paper, and / or a laminate, is coated.

5. The method according to claim 1 or 2, wherein a workpiece is produced in the form of a laminate and / or a compact plate.

6. The method according to any one of claims 4 to 5, wherein a resin, preferably a urea resin (UF), a melamine resin (MF) and / or a phenolic resin (PF), containing coating (10,11 ) or impregnation is used.

7. The method of claim 1 or 2, wherein a wood-based material surface is smoothed with the work surface without cutting.

8. The method according to any one of claims 1 to 7, are removed in the deposits from the working surface of a pressing tool in the form of a roller, a press plate, a press belt, in particular a double belt press, and / or a molded part.

9. The method according to any one of claims 1 to 8, wherein the laser system (16,17,27) a pulsed laser beam (18) with pulse lengths of less than 1 microseconds and / or a laser beam (18) with a laser power of 80 to 120 Watt produced.

10. The method according to any one of claims 1 to 9, wherein the laser beam (18) of the deposits at least predominantly absorbed and / or from the

Working surface is at least predominantly reflected.

11. The method according to any one of claims 1 to 10, wherein the laser system (27) tuned to a cycle of the pressing device (20) in a pressing space (24) of the pressing device (20) is retracted and extended.

12. pressing device (1,20) for producing a workpiece, in particular in the form of a wood-based panel, a coated wood-based panel (9,23,26) and / or a laminate, preferably for carrying out the method according to one of claims 1 to 11, with at least a pressing tool (2, 3, 21, 22) for pressing the workpiece (9, 23, 26), wherein the at least one pressing tool (2, 3, 21, 22) has a working surface which comes into contact with the workpiece during pressing characterized in that a laser system (16, 17, 27) is provided, that the laser system (16, 17, 27) is designed to irradiate the working surface with a laser beam (18) and that the laser system (16, 17, 27) is designed for delivering a laser beam (18) suitable for removing deposits adhering to the working surface.

13. Press device according to claim 12, characterized in that the pressing tool is a roller, a press plate, a

Press belt, in particular a double belt press, and / or a molded part.

14. Press device according to claim 12 or 13, characterized in that that the pressing tool has a metallic, a heatable, a structured and / or a profiled work surface.

15. Press device according to one of claims 12 to 14, characterized in that the laser system (27) is mounted on a device (25) which is tuned to a cycle of the pressing device (20), preferably for transporting the workpiece (23,26) , in and out of a pressing space (24) of the pressing device (20).