EP2998052B1 - Method and device for narrow surfaces coating of plate-shaped semi-finished products or workpieces - Google Patents

Description

The invention relates to a method and a device for narrow-surface coating of plate-shaped semi-finished products or workpieces, according to the preamble of claims 1 and 7. Such a method and such a device are of DE29819350U1 known.

Plate-shaped semi-finished products made of wood or wood-based materials, such as chipboard or medium-density fiberboard, are used in industry u. a. used for the production of inexpensive furniture panels for living and kitchen furniture. The plate-shaped semi-finished products have a thickness between 16 mm and 100 mm depending on the mechanical load of the future furniture panel. To protect the surface and decorative reasons, the two top surfaces of the plate-shaped wood material are coated with a top layer of small thickness of wood material, veneer, foil, plastic or metal. The conclusion of the narrow surfaces on the outer end-side circumference of the provided with cover layers wood materials is carried out regularly by a narrow-surface coating.

For the purposes of the present application, a "narrow-surface coating" or an "edge material" is understood to mean a rod-shaped or strip-like coating material made of plastic, paper, wood, wood veneer or other suitable materials which has the most form-fitting veneering of the frontal narrow-surface region between the two outer layers of a coated one Wooden board serves. Common narrow-surface coatings consist of PVC, ABS, PP, melamine, paper, aluminum, wood veneer or solid wood and are generally used in thicknesses of 0.25 mm to 4 mm.

For special applications, such. As in damp rooms or kitchen furniture, there is also the requirement that the seal between the narrow surface and the adjacent cover layers of the coated wood-based panel is quasi-seamless to make the ingress of water or other liquids such. As cleaning agents to prevent in the region of the joint connection between the narrow surface and the adjacent top surfaces.

The application of the narrow-surface coating on the frontal narrow surface of the plate-shaped wood material is usually carried out by gluing with a fast-curing binder, such as a hot melt adhesive, a cohesive connection between the, not visible after bonding underside of the narrow surface band and the surface of the end face of the plate-shaped wood material produces.

For joining the narrow surface band on the frontal narrow surfaces known Kantenanleimmaschinen or processing systems are used depending on the number / lot size and the dimensions of the plates to be processed, in which already coated with two cover layers wood board passes through several workstations in which the surface of the plate formatted and is coated. Initially, the still uncoated narrow surface of the already coated with the two cover layers plate is machined by cutting tools, such as cutters or saws to the desired shape and size.

Subsequently, with known means, such as a roller or a surface applicator, the adhesive, z. As a hot melt, applied to the narrow surface of the plate to be coated. Preference is given to using hot melt adhesives based on polyurethane. For narrow surface bands with already applied hotmelt adhesive, the adhesive is activated by hot air nozzles or plasma lasers.

Then, the supply of the applied narrow-surface material, which is usually stored as a belt / Keul or magazine. The front edge of the edge material is joined together at the front edge of the wood-based panel provided with the cover layers and formatted. For this purpose, the edge materials are adapted to the workpiece thickness of the plate. The width of the narrow surface band is regularly selected larger than the desired thickness of the coated material plate. As a rule, a two-sided supernatant of about 2 to 3 mm is selected, which is removed in a later step, together with excess adhesive, by machining. This is to a uniform and tight completion of the joint connection can be realized. Subsequently, the narrow-surface material is separated at the end of the plate. This is usually done with a small protrusion on the front and rear edges of the plate.

After application of the narrow band, the tape is pressed by a plurality of pressure-loaded pressing elements, such. B. pressure rollers or pressure shoes, pressed onto the narrow surface of the plate. In this pressure zone, the hot melt adhesive between edge material and the narrow surface of the plate is compacted. The viscosity of the adhesive used is very low in this phase, so that it comes regularly despite the use of cooled pressure elements to leakage of the hot melt adhesive on the surfaces of the plate.

In the subsequent flush milling, the two-sided projection of the narrow-surface material is removed by machining together with the leaked adhesive. In order to realize a low roughness of the cut surface despite the high feed rates of the workpieces, multi-edged milling tools are used, which operate at speeds of 10,000 rev / min to 16,000 rev / min. As a result of the frictional heat occurring, there is an unwanted reactivation of the hot melt adhesive used after the already initiated solidification. In turn, thin-bodied hot-melt adhesive emerges from the adhesive joint, which leads to contamination of the milling and grinding tools, the guide devices of the machine and the workpiece surfaces. These contaminants must subsequently be laboriously and partially manually eliminated.

Therefore, after pressing the narrow-area material in many cases, a liquid separating or cooling agent is sprayed onto the surface of the narrow-area material, whereby the hot-melt adhesive solidifies faster. At the same time, the liquid separating or cooling agent is intended to prevent the chips from adhering to the workpiece as a result of the electrostatic charging during the subsequent cutting processes.

Such liquid coolant are from the DE 100 42 431 C1 known. In the described method, the supernatant of an edge band is milled off by means of an edge band milling cutter. In this case, before the milling on the edge band and / or the plate, the electrostatic charge of the wetted areas and / or the milling chips preventing release agent applied. This should be achieved that the resulting chips are better removed, so that the further processing is simplified after Kantenbandanleimen. Thus, the resulting milling chips can be better removed by suction because they no longer adhere to the plate surface or the edge band. The agent used consists of a mixture of water, alcohol and surfactant.

Besides that is from the EP 2 522 476 A2 a method for producing a coated plate element of wood material with an edge strip known. In this case, the hot melt adhesive is applied to the uncoated edge region of the plate element and the, held on a roll edged edge strip with a slight excess with its adhesive side pressed against the adhesive-coated edge region of the plate member. In this case, the, emerging from the adhesive joint during the setting process as a result of the applied pressure adhesive and the excess of the edge strip of the edge portions of the plate member at the top and / or bottom is removed by machining. For better processing is on the edge regions of the top and / or bottom of the plate member before the setting process of the adhesive, a substance applied, which disables the, exiting from the adhesive joint excess adhesive residues in their adhesion, so that form non-adhesive adhesive particles, which are removed when removing the protruding edge strip from the edge area with. Advantageously, the substance is applied in strips on the edge areas of the top and bottom. The substance used consists of a water-dispersed, polymeric fluid.

A disadvantage of the use of the known liquid separating or cooling means that can not be prevented that these liquids penetrates through the not yet solidified during spraying adhesive joint in the space between the narrow surface material and the narrow surface of the plate-shaped semifinished product and there the adhesion of the adhesive is prevented or prevented on the narrow surface. As a result, it comes regularly at a later date, especially in the intended use of the furniture, to distortions and separation phenomena of the narrow-surface material and thus to the loss of use value.

Alternatively to the use of liquid separating or cooling agent is from the DE 10 2007 014 832 B3 a method for the narrow-surface coating of plates with a core layer of low density, in which the binder (hot melt adhesive) is cooled by blowing air onto the already bonded edge band or by a running metal rail. A disadvantage of the air cooling is the low efficiency, which does not allow sufficient cooling at high working and feed speeds of the plates to be processed at the maximum allowable flow velocity at the plants. The same applies to the alternative use of known air-cooled rails.

In other fields of technology is also the use of elevated pressure fluids (gases or liquids) are known, which cool by the relaxation (reduction of pressure) and thus serve as a coolant.

So will in the US 3,568,377 A described a cooling device for a grinding wheel, wherein the pressurized gas, for. As nitrogen or carbon dioxide, is applied through nozzles on the grinding wheel and contributes to the cooling. In the EP 0483561 A1 For example, pressurized liquid carbon dioxide is used to cool a specific lubricant whose viscosity increases with decreasing temperature.

Due to the growing demand for low-cost furniture panels and increasing competitive pressure from imports, manufacturers are increasingly turning to extremely low-cost thin-film coating materials. So z. In the Low-budget range coated papers with a grammage of only 24g / m ^{2 were} used.

In order to further reduce the manufacturing costs in mass production, edge banding machines or processing systems are increasingly being used, which enable feed rates of the plate-shaped semi-finished products of up to 300 m / min.

Despite this significant increase in productivity, the quality (appearance, feel, function) of the plates provided with these narrow-surface coatings must meet the demands of the market.

The object of the invention is to eliminate the disadvantages of the prior art and to provide a method and apparatus for narrow-surface coating of a plate-shaped semifinished product or workpiece in mass production and mass production, the quality of processing narrow-area materials, in particular small thickness, with respect to the State of the art allow significantly higher feed rates.

The process should be able to be used at comparable unit costs on known Kantenanleimmaschinen or processing systems without significant changes in the technological process must be made. The cost-intensive and quality-endangering use of liquid coolants should be completely eliminated.

According to the invention the object is achieved with the features of claims 1 and 7. Preferably, refinements and developments of the invention are the subject of the respective dependent subclaims.

In the method according to the invention for narrow-surface coating of plate-shaped semi-finished products or workpieces made of wood or wood materials, in which the already coated with two cover layers plate-shaped semi-finished pass through several workstations, the prepared narrow surface by means of a hot melt adhesive, which directly or indirectly heated and with the applied thin surface material is connected under the action of pressure and temperature and the narrow surface and the adjacent cover layers of the plate-shaped semi-finished machined, before and / or after and / or after a machining at least the machined or machined areas of the plate-shaped semifinished product by a flow of liquid and / or gaseous carbon dioxide or a mixture of carbon dioxide and air cooled.

The connection of the narrow surface with the narrow-surface material by means of the hot-melt adhesive is realized by means of known methods. In this case, the hot melt adhesive can be applied cold to the prepared narrow surface and then heated or hot applied to the prepared narrow surface and possibly reheated.

Alternatively, the hotmelt adhesive may also be applied hot or cold to the narrow-area material or may already be integrated in the narrow-area belt, wherein at least the cold hot-melt adhesive is still heated to produce a connection with the narrow area.

It is also possible to introduce hot melt adhesive into the material of the plate-shaped semifinished product or workpiece, which then melts upon heating of the semifinished product in the area of the narrow surface and realizes an adhesive connection with the narrow-area material.

In order to prevent the undesired leakage of the adhesive used from the joining zone of the narrow-surface material and the plate-shaped semifinished product or workpiece, at least the joining zone according to the invention after the pressing of the narrow-face material a flow of liquid and / or gaseous carbon dioxide or a mixture of liquid and / or gaseous Exposed to carbon dioxide and air. The cooling effect is realized by the conversion of liquid carbon dioxide into gaseous carbon dioxide. In addition, other areas of the semifinished product and the tools used or parts thereof by the same flow of liquid and / or gaseous carbon dioxide or a mixture of liquid and / or gaseous carbon dioxide and air or by a flow of the fully converted by phase conversion of carbon dioxide or a mixture of gaseous carbon dioxide and air are cooled.

For cooling with a flow of liquid carbon dioxide or a mixture of liquid and gaseous carbon dioxide or a mixture of liquid carbon dioxide and air, the liquid carbon dioxide is preferably introduced in a line directly to the area to be cooled of the semifinished product or tool, the carbon dioxide a Pressure between 5.6 MPa to 8 MPa (56 bar to 80 bar) at an ambient temperature between 20 ° C and 40 ° C. With this pressure, the liquid carbon dioxide preferably exits from a punctiform or area-effect nozzle into the immediate surrounding area of the area of the semifinished product or tool which, for example, has normal pressure, so that the liquid carbon dioxide is converted into gaseous carbon dioxide and expanded. Both physical effects overlap and lead to the strong cooling effect.

It was found that with a volume flow of 0.01 l / min - 0.02 l / min of carbon dioxide (1 liter of liquid gas corresponds to approx. 640 l of air) a better cooling effect is achieved than in the previous use of 6 m ³ to 10 m ³ compressed air / min according to the prior art. Carbon dioxide has a large volumetric cooling capacity and thus a higher efficiency at a given volume compared to atmospheric compressed air. This makes it possible to specifically influence the temperature profile in the joining zone and in particular the temperature of the applied adhesive layer.

The cooling performance is mainly due to the amount of carbon dioxide exiting, i. H. by the volume flow of liquid carbon dioxide. If only a small cooling capacity, but a high volume flow of fluid impinging on the semifinished product is needed, the liquid carbon dioxide can be mixed with an additional gas, for example. Air or gaseous carbon dioxide. In this case, the additional gas in a closed mixing chamber, d. H. before the liquid carbon dioxide is discharged into the surrounding region of the region of the semifinished product to be cooled, or directly into the surrounding region of the region of the semifinished product to be cooled.

The additional gas preferably has the same pressure as the liquid carbon dioxide, but may also be applied with a different pressure. In particular, when admixed in a closed mixing chamber, the pressure of the additional gas and its temperature are preferably selected so that the phase transformation of the liquid carbon dioxide into gaseous carbon dioxide does not take place or not yet completely in the closed mixing chamber.

A complete phase transformation of the liquid carbon dioxide into gaseous carbon dioxide in the closed mixing chamber is also possible.

The mixing ratio of liquid carbon dioxide and additional gas is determined by the volume flow and temperature of the mixed fluid required in the area to be cooled of the semifinished product and can be between 1: 600 to 1: 6000, the first number being the volume of the liquid carbon dioxide in liters and the second number indicates the volume of additional gas in liters.

Since modern unmanned edge banding machines or processing systems for technological and occupational safety reasons are usually completely enclosed, it is possible, any or all workstations where by the machining or by other, heat generating tools or machine elements, a significant heat input into the joint zone of Narrow surface material and the plate-shaped semifinished product or workpiece takes place to cool temporarily and locally targeted.

Advantageously, by controlling or regulating the volume flow and / or its temperature, the temperature profile in the joining zone can be adapted to the physical and chemical properties of the adhesive used and to the technological processing conditions of production (feed speed of the edge banding machine, rotational speed of the cutting tools, etc.).

In particular, it is in profiled and undercut narrow surfaces, as they are, for example, in door rabbets, handles of kitchen cabinet doors or the like, in the step of connecting the narrow-surface material with the narrow surface possible to cool the individual profile areas immediately after joining specifically, so that the adhesion of the Edge material is improved.

Preferably, a laminar flow of gaseous carbon dioxide or a mixture of carbon dioxide and air is used for the cooling of individual or all relevant workstations. Thereby, the temperature profile in the joining zone and in particular in the adhesive layer can be discretely influenced temporarily and locally.

In a likewise preferred variant of the method, a turbulent, in particular a pulse-like flow of gaseous carbon dioxide or a mixture of carbon dioxide and air is used for cooling individual or all relevant workstations. As a result, the temperature profile in the case of stochastic phenomena (unexpectedly high temperature rise in the joining zone as a result of inhomogeneous material properties of the joining partners) can be adapted to the process.

When using larger volume flows, it is now possible to increase the feed rates of the plates to be processed in edgebanders or processing systems without it due to the friction and heat of reaction during machining of the narrow surfaces to the unwanted leakage of liquefied or low-viscosity adhesive or which reactivates.

A significant advantage of liquid or gaseous carbon dioxide or a mixture of carbon dioxide and air as a coolant is the high availability of carbon dioxide on the one hand in the air, from which the carbon dioxide is removed and liquefied and in which it can be released after use (balanced carbon dioxide). Balance sheet), and on the other hand as a waste product of the chemical industry and the resulting low operating costs.

In addition, carbon dioxide acts flame-retardant, so that it can be used preferably and safely even in places with a fire hazard (use of lasers to heat the joint zone).

To avoid health burdens of the monitoring personnel or the machine operator and -inrichter and to reduce the manufacturing process costs is in the housed systems advantageously the possibility of recovery, in which the gaseous coolant sucked under the floor and can be reused after a cleaning and treatment process.

Another technological advantage of the use of liquid and / or gaseous carbon dioxide or a mixture of carbon dioxide and air as a coolant is that on the surface of the workpiece, the processing tools and the machine tool no residues, such as when using known liquid cooling or release agent, remain, which would have to be laboriously removed.

Another advantage of using liquid and / or gaseous carbon dioxide or a mixture of carbon dioxide and air as a coolant is the chemical inactivity, so that there is no adverse effect on the plate-shaped semifinished product, the hot melt adhesive or the narrow surface coating.

Also advantageous is the anti-inflammatory and fire-retardant action of the liquid and / or gaseous carbon dioxide, so that the method can preferably also be used in edge banding machines and processing systems in which the activation of the hot melt adhesive takes place by laser or hot air nozzles.

The present after the phase transformation gaseous carbon dioxide or the mixture of gaseous carbon dioxide and air has - depending on the mixing ratio - a, compared to the ambient temperature, low temperature in the range of -78 ° C to + 30 ° C and can thus for the cooling Further areas of the semifinished product, for example. The top surfaces of the plate-shaped semifinished product, the tools and workstations or the environment of the workstations are used. Thus, the thermal loads on the tools and workstations and the effects of fluctuations in the environmental conditions of the workstations can be minimized to the processing of the semifinished product. Thus, the mixture of carbon dioxide and air, which is present after the cooling of the narrow surface areas of the semifinished product, for. B. sucked by a suction device of the workstation and used to cool the engine or other, thermally loaded device of the workstation.

The inventive device for narrow-surface coating of plate-shaped semi-finished products or workpieces made of wood materials with a Kantenanleimaschine or a processing system in which applied to the prepared narrow surface a hot melt adhesive and heated directly or indirectly, with the applied narrow-area material with the narrow surface of the formatted plate-shaped semi-finished product under the action of Pressure and temperature connected and the narrow surface and the adjacent cover layers of the plate-shaped semi-finished machined, has means which are suitable before and / or during and / or after a machining at least the machined or machined areas of the joined plate-shaped semifinished product by a flow of liquid and / or gaseous carbon dioxide or a mixture of carbon dioxide and air to cool.

Preferably, the device comprises means for the passage and supply of the liquid and / or gaseous carbon dioxide or a mixture of carbon dioxide and air, which means as media lines with a point or area acting nozzle, a perforated pinch roller, a pressure shoe, an air shower or an air curtain formed are.

Advantageously, the passage of the liquid and / or gaseous carbon dioxide or a mixture of carbon dioxide and air through the hollow shaft of a tool, preferably a cutting tool, up to the working zone or directly to the processing area of the tool, in particular the cutting. Thus, at the same time the processing area of the tool can be cooled particularly intensively for cooling of areas of the semifinished product

The device preferably has means which are suitable for controlling or regulating the volume flow and / or the flow velocity and / or the temperature of the flow.

Furthermore, the device is preferably housed and has means for extracting the gaseous carbon dioxide or the mixture of carbon dioxide and air. This extraction can be realized by means already existing for chip extraction from areas in which the semifinished product is machined. However, separate means for suction are possible.

In addition, the apparatus advantageously comprises means for recycling and reusing the gaseous carbon dioxide or the mixture of carbon dioxide and air.

The method according to the invention and a device for narrow-surface coating of a plate-shaped semifinished product or workpiece are described in more detail below with reference to an embodiment and in which FIGS. 1 and 2 shown. In addition, the show FIG. 3 a device in which individual areas of a narrow surface are selectively cooled, and the FIG. 4 a milling machine as an example of a workstation in which the generated mixture of gaseous carbon dioxide and air is used to cool the workstation.

FIG. 1 shows in the lower part in a highly schematic representation of the workstations of a conventional edge banding machine for narrow-surface coating of a plate-shaped semi-finished, are made with the furniture panels in a three-layer manufacturing process according to the prior art.

The graph above shows the temperature profile (dash-dotted line) in the joining zone above the working area in this prior art edgebander.

The vertical axis of the diagram shows the temperature (T) in degrees Celsius, the horizontal axis represents the length L in meters (m) of the edge banding machine.

The diagram shows the softening temperature E (in degrees Celsius) and the heat resistance W of the hotmelt adhesive EVA / KS 350 used by means of two further, horizontally extending auxiliary lines.

For the purposes of this application, softening temperature E is understood to mean the temperature at which a polymer deforms, eg. B. in the ring and ball method under the weight of the ball (DIN EN 1238).

Since with many hotmelt adhesives no exactly defined softening temperature, but only one temperature range can be specified, the heat resistance W indicates the temperature at which the adhesive layer is able to withstand a temperature stress without deformation for longer periods of time ( Have not, G .: sticking. Basics, technology, applications. Springer-Verlag Berlin, Heidelberg, 2008 ).

In the adhesive used in the embodiment EVA / KS 350 (see also Fig. 1 and 2 ), the softening temperature E was about 125 ° C and the thermal stability W at 90 ° C. When the thermal resistance W is exceeded, the hot melt adhesive regularly comes out of the joint and, as a consequence, sticks to the tools and contaminates the surface of the board.

FIG. 2 shows in the lower part in a highly schematic representation of the work stations an edge banding machine for narrow-surface coating of a plate-shaped semifinished product, are made with the furniture panels in a three-layer manufacturing process by the novel process.

For better comparability with the known edge banding machine Fig. 1 were used (as far as possible) the same reference numbers 1 ... 17 of the individual workstations.

In the above illustration of Fig. 2 Again, the temperature profile in the joining zone in a prior art edge banding machine (dashed line) and for direct comparison with the cooling method according to the invention (solid line) is shown. The areas marked "X" and "Y" at the machine length L represent a possible shortening of the machine due to the use of the method according to the invention whose size is process-dependent.

The prior art edge banding machine ( Fig. 1 ) allows, depending on the size of the workpieces to be machined, the narrow surface coating of about 3000 workpieces per hour. The machine achieves a feed rate v of the traversing plates P of up to 110m / min. The edge banding machine formats and glues PVC, ABS, PP, melamine, paper, veneer edging or solid wood edge banding in thicknesses from 0.25 mm to 4 mm with 4 mm or larger edgebandings.

In the housed basic machine, all workstations are installed. For the simultaneous, two-sided processing of two narrow surfaces of the moving furniture panels, the workstations are duplicated. For better illustration, the housing of the edge bander is not shown.

In the work station (1), the plate-shaped semifinished product (P) to be processed is produced in a known edge banding machine according to the prior art ( Fig. 1 ) applied with a release agent application nozzle a fluid in the form of dispersed polymer, alcohol, surfactants on the surfaces of the plate-shaped semifinished product to be processed in order to prevent the subsequent adhesion of adhesive residues.

This technological auxiliary process and the device used to carry it out can be dispensed with in the innovative process (cf. Fig. 2 ).

In the workstation (2), the formatting of the narrow surface is carried out to the desired shape. Here, depending on the narrow-area material used, the required geometry (straight course, groove, soft form, woodcut) of the narrow surface is produced with known cutting tools (milling cutter, grooving saw).

In the Fig. 2 shown selectively, surface cooling K with liquid and / or gaseous carbon dioxide or a mixture of carbon dioxide and air takes place depending on the adhesive used and the technological manufacturing parameters, in particular the feed rate of the edge banding machine and the cutting speed of the cutting tools before, during and after machining, to prevent the formation of built-up edges on the cutter and the melting of the polymer in the chipboard.

The workstation (3) is designed as a gluing station, in which the hot melt adhesive used is applied by means of rollers on the two narrow surfaces of the future furniture panel to be coated. The temperature of the hot melt adhesive is 210 ° C when wetting the rollers. When bonding special edges, plasma lasers, diode lasers or hot air nozzles are used to melt the adhesive. For standard edges, glue rollers, surface application nozzles, infrared radiators or hot air showers are used to activate the adhesive.

In the workstation (4), the lateral supply of the edge material or the solid wood edging takes place. Upon coincidence, the edge material is advanced synchronously with the plate at the speed of the conveyor belt of the edge banding machine. The edge magazine can consist of several individual magazines. The beginning of the edge material is joined together at the front edge of the formatted plate. The edgeband materials are adapted to the board thickness and have a two-sided overhang of approx. 2 mm.

In the work station (5), the edge material is cut off at the end of the plate by a Kappmesser. This usually happens with a small protrusion at the trailing edge of the workpiece.

The workstation (6) comprises the pressure zone, which consists of the pressure roller and other pressure elements, which with a contact pressure of 2 - 4 bar the hot melt adhesive compact between edge material and plate. The viscosity of the hotmelt adhesive used is still very low when the pressure zone is reached at a temperature of 180 ° C., so that in the case of devices according to the known prior art ( Fig. 1 ) comes to a leakage of the adhesive to the surfaces of the plate.

In the edgebander according to Fig. 1 the cooling is done by known air showers, vortex tubes, air curtains or cooled pressure shoes.

In the edgebander according to Fig. 2 the cooling takes place via a plurality of punctiform and flat-acting nozzles, through which the gaseous carbon dioxide or a mixture of carbon dioxide and air flows before, during and after the pressing on the joining zone and the adjacent plate areas and by the pressure elements used. In this case, the cooling flow of the carbon dioxide is preferably used with a temperature of max. -78 ° C finely dosed used for cooling the adhesive joint. This makes it possible to optimally temper the adhesive zone as a function of the hotmelt adhesive used and its parameters.

Due to the significantly higher efficiency of the innovative cooling process, the pressure zone can be shortened. As a result, the length of the machine tool can advantageously be shortened in the case of the new production of generic edge banding machines with at least the same productivity. This results in lower procurement and maintenance costs for the machine tool and less space required in production.

The shortening of the pressure zone is in Fig. 2 symbolized by two broken lines. The saved length of the pressure zone is shown as distance X.

In the workstation (7) according to the prior art ( Fig. 1 ) immediately after the pressing of the edge material, the adhesive eye cooled down by means of vortex tubes, air showers, air curtains or cooling bars. The average air consumption of these cooling methods according to the prior art is up to 10 m ³ / min, larger systems up to max. 50 m ³ / min.

In the method according to the invention ( Fig. 2 ) can because of the significantly higher cooling capacity on the workstation (7) according to Fig. 1 completely dispensed with.

As a result, the length of the machine tool can be shortened for the same productivity in the new production of generic edge banding machines. This results in lower manufacturing and maintenance costs for the machine tool and a smaller footprint in manufacturing. The possible shortening of the length L of the edge banding machine is in Fig. 2 symbolized by two broken lines. The saved length of the machine tool is shown as distance X.

In the work station (8) are cut off by two chop saws the protruding surfaces of the edge material at the leading edge or trailing edge of the plate.

In the Fig. 2 shown cooling with gaseous carbon dioxide or a mixture of carbon dioxide and air, depending on the used narrow-area materials and adhesives before, behind and / or at the workstation for cooling the cutting tools and the edge material.

In the work station (9), the pre-milling of the edge material, which protrudes at the top and bottom of the plate takes place.

In known systems according to the state of the art, in the case of milling, unwanted reactivation of the hot-melt adhesive, heating of the edge and, as a consequence, contamination of the tools, the machine tool and the workpiece surfaces occur.

Here will be (as in Fig. 2 shown) cooled by one or more nozzles, the cutting tool, the plate surface and the edge before and after milling locally or partially by the carbon dioxide or a mixture of carbon dioxide and air. Due to the equally preferred cooling of the tools used, for. B. by the flow of liquid or gaseous carbon dioxide through the hollow shaft of a cutting tool, the formation of built-up edges can be prevented and the tool life can be significantly increased.

As a result, after the heat input during machining, the temperature in the joining zone is lowered in a timely manner, so that - in contrast to the prior art - the technologically critical limit of the thermal stability W is significantly undercut (see Curves of the actual temperature in FIG Fig. 2 , upper illustration).

In the work station (10), the protruding edges of the edge material are milled flush with the plate surface by two cutters, so that it comes through the use of high-speed milling tools to a new unwanted reactivation of the hot melt adhesive.

According to the invention, the main and secondary cutting edges of the milling tools, the narrow surface band and the adjoining surface of the plate are cooled by gaseous carbon dioxide or a mixture of carbon dioxide and air before, during and after milling by means of a plurality of areal as well as punctiform nozzles. Fig. 2 ). This effectively prevents reactivation of the adhesive and positively influences the machining process.

In the workstation (11) the thin edges of the edge material are (optionally) milled by two form cutters. When using thick edges z. T. milled different radii, so that it comes through the repeated use of high-speed milling tools to a new, unwanted reactivation of the hot melt adhesive. Here, according to the invention, the cooling with gaseous carbon dioxide takes place locally via nozzles directed from outside onto the tool, the plate surface and the edge material ( Fig. 2 ). Depending on the process parameters, the cooling of the cutting tools (optional) additionally takes place directly through the coolant guided through the hollow tool shank.

In the workstation (12), the front and rear edges of the edge material are profiled with one or two corner rounding devices. Due to the small available time window due to the high feed speeds in the vertical direction, high temperatures are generated at the cutting edges of the milling tools. As a result, this process heat causes the leading and trailing edges of the edge material to melt and the edge material to be thermally stressed too high.

Here are inventively (see. Fig. 2 ) the tools, the edge material and the adjacent plate surface before, during and after milling by a, adapted to the technological process parameters (cutting speed, feed rate, adhesive) volume flow cooled with gaseous carbon dioxide or a mixture of carbon dioxide and air , Depending on the process parameters, the cooling of the cutting tools preferably takes place through the coolant guided through the hollow tool shank.

As a result, after the repeated application of heat during machining, the temperature in the processing zone is again reduced, so that the technologically critical limit of the thermal stability W is clearly undershot compared to the course of the actual temperature in the prior art (cf. Temperature in Fig. 2 , upper illustration).

In the work station (13), one or two profiled scraper units are optionally used for processing the surface of the edge when processing plastic edges. A thin chip (0.08 mm to 0.15 mm) is removed, which is to remove the previously formed milling burrs. This creates a uniform surface. The frictional heat generated by the single-edged tools without the previous one Cooling with carbon dioxide at high feed or cutting speeds extremely high temperatures at the main cutting edge, which lead to a critical increase in temperature in the joining zone. Here, according to the invention, the tool, the plastic edge and the plate surface are cooled by a plurality of nozzles with carbon dioxide or a mixture of carbon dioxide and air ( Fig. 2 ).

On the in the prior art (see. Fig. 1 ) customary application of release agents to prevent smearing by adhesive residues can be advantageously dispensed with.

In the workstation (14) are removed by flat scrapers any adhesive residues on the surfaces of the plate. Here too, high temperatures occur at the cutting edges, which, without the innovative gas cooling with carbon dioxide at the low viscosity of the hot melt adhesive to smear the blades of the flat scraper blade, so that the tools must be changed and cleaned in shorter cycles and it comes to interrupting the manufacturing process ,

Here, according to the invention, the tool, the edge material and the plate surface are cooled with gaseous carbon dioxide or a mixture of carbon dioxide and air by a plurality of nozzles from the outside ( Fig. 2 ).

On the hitherto customary application of release agents (cf. Fig. 1 ) to prevent smearing by adhesive residues can be advantageously dispensed with.

In the work station (15), the surfaces of the plate-shaped workpiece are polished and cleaned by sisal, cloth or fiber discs by paired Schwabbelaggregate. The buffing wheels work in synchronism or counter-rotation to prevent the hot melt adhesive in the joining zone from being reactivated. As a result, the efficiency of the discs is significantly reduced.

Here, according to the invention, the tool, the edge material and the plate surface are cooled by gaseous carbon dioxide or a mixture of carbon dioxide and air through a plurality of areal nozzles.

As a result of the actual temperature in the working zone, which has been significantly reduced compared with the prior art at this stage of the process (see Curves of the Actual Temperature in FIG Fig. 2 , top illustration) can be dispensed with in the inventive solution entirely or on a large part of the buffing wheels, since the outlet of hot melt adhesive in the upstream workstations is no longer to be feared. This results in lower manufacturing and maintenance costs and a reduced space requirement (symbolized by two broken lines and the distance Y, which corresponds to the saved length of the buffing station) of the present invention Edgebander.

Again, the usual application of separating or cooling agents (see. Fig. 1 ) to prevent smearing caused by adhesive residues

In the work station (16) the edges of the narrow surface are finally ground by two grinding units, so that again a significant heat input into the workpiece and a reactivation of the hot melt adhesive occurs. When grinding aluminum edges, several sanding belts with different grain sizes (coarse and fine sanding) must be used due to the process. Among other things, this leads to the strips sticking together with aluminum and solid wood particles. This causes extreme smearing of the aluminum in the belts. In these processes, according to the state of the art, rapeseed oil or other liquids of equivalent action are used as coolants, which lead to severe contamination of the plate surfaces.

According to the invention, the grinding tools, the edge material and the plate surface are cooled by a plurality of areal nozzles with gaseous carbon dioxide or a mixture of carbon dioxide and air ( Fig. 2 ). By using carbon dioxide, no coolant residues remain on the workpiece.

In the workstation (17) optional grooved units can be used.

Due to the use of binders in the plates, the process of milling the grooves also causes process contamination of the tool cutting edges.

The local cooling of the tool cutting edges, the plate and the edge with gaseous carbon dioxide or a mixture of carbon dioxide and air before and during milling, the process temperature can be significantly reduced in this work area (see curves of the actual temperature in Fig. 2 , upper illustration).

FIG. 3 shows a device in which individual areas of a narrow surface are selectively cooled. This is particularly advantageous in profiled or undercut narrow areas. In Fig. 3 is a plate (P), which moves in a direction (R) in the plane of drawing, shown in cross-section. The plate (P) has a first cover surface (100) and a second cover surface (110) and a profiled narrow surface (120). In such a profiled or undercut narrow surface (120), the narrow-surface material (20) by a plurality along the transport direction (R) of the plate (P) and along the width of the narrow surface (120) staggered pressing elements or by a profile on the Narrow surface (120) moving away pressure element over the profile of the narrow surface (120) across the first cover surface (100) to the second top surface (110) of the plate and pressed. At first, a first region (121) of the Heated narrow surface (120) near the first top surface (100) and the narrow-surface material (20) pressed in this area.

Thereafter, in the transport direction (R) of the plate (P), a second region (122) of the narrow surface (20) adjacent to the first region (121) is positioned closer to the second top surface (110) of the plate (P) , heated and the narrow-surface material (20) pressed in this area.

Already at this processing point of the plate (P), the first region (121) of the narrow surface (120) can be cooled by a targeted application of the flow of liquid and / or gaseous carbon dioxide or a mixture of carbon dioxide and air through a first cooling unit (31) so that a detachment of the narrow-area material (20) from the narrow surface (120) due to restoring forces in the narrow-area material (20) in the first region (121) is prevented. This localized along the narrow width, ie along the course of the narrow surface (120) between the first cover side (100) and the second cover side (110) offset pressing and cooling is now continued as long as for other areas of the narrow surface (120) to the narrow surface (120) is completely covered with the narrow-area material (20). In Fig. 3 schematically shown are six areas (121 to 126) of the narrow surface (120) and six each of a specific area (121 to 126) associated cooling units (31 to 36) along the transport direction (R) of the plate (P) at least partially offset from each other are arranged.

FIG. 4 shows a milling machine (40) as an example of a workstation in which the generated mixture of gaseous carbon dioxide and air is used to cool the workstation itself and to create defined environmental conditions for the workstation.

Shown schematically are a plate (P) and the milling machine (40), which processes the narrow surface (120) of the plate (P) with a milling tool (41). The narrow surface (120) according to the invention is cooled by a flow of liquid and / or gaseous carbon dioxide or a mixture of carbon dioxide and air. This is in the area of the milling tool (41) before a carbon dioxide-air mixture with a low, specially set temperature.

The milling tool (41) is connected via a tool holder (42) with an engine block (43) and housed with a housing (45). In the engine block (43) for cooling the motor, a fan (44) is arranged, which generates an air flow from the milling tool (41) facing side of the engine block (43) to the rear of the engine block (43) and thus cools the engine. For this purpose, on the milling tool (41) facing side of the engine block (43), the air or the air mixture present there sucked, which with the arrows in there Fig. 4 is shown.

Since the housing (45) forms a closed space around the milling tool (41) and the tool holder (42), the by the fan (44) sucked carbon dioxide-air mixture between the milling tool (41) and narrow surface (120) of Plate (P) is present, the engine block (43) effectively cool. Through openings on the back of the engine block (43), the carbon dioxide-air mixture is discharged or sucked by the fan wheel (44) to the environment, which is indicated by the arrows in Fig. 4 is shown.

If the entire milling machine (40) or the environment of the workstation of a housing (50) is housed, which includes, for example. Also, the top surfaces of the plate (P) with, from the engine block (43) exiting air mixture for adjustment defined environmental conditions are used in the environment of the workstation.

Overview of used reference numerals

e

softening

K

Cooling (by means of liquid and / or gaseous carbon dioxide or a mixture of carbon dioxide and air)

L

Length (the edge banding machine)

P

Plate (plate-shaped semi-finished product or workpiece)

T

temperature

v

Feed rate (of the edge banding machine / processing system)

X

reduced length of the edge banding machine (due to the omission of the conventional cooling device)

Y

reduced length of the edge banding machine (due to the elimination of buffing units)

1-17

workstations

20

Narrow surface material

31-36

first to fourth cooling units

40

milling Machine

41

milling tool

42

tool holder

43

block

44

fan

45

Housing of the milling machine

50

Housing the environment

100

first cover page

110

second cover page

120

narrow surface

121-126

first to fourth area of the narrow area

Claims (13)

1. Method for narrow-surface coating of planar semifinished products or workpieces (P) made of wood or of wood materials such as chipboard or medium-density fibreboard, using edge-banding machines or machining systems in which the planar semifinished products (P) that are already coated with two top layers pass in a continuous manner through a plurality of work stations (1-17), the prepared narrow surfaces (120) being bonded to the narrow-surface material (20) that is to be applied, under the effect of pressure and temperature (T) and by means of a hot-melt adhesive that is heated directly or indirectly, and the narrow surface (120) and the adjacent top layers of the planar semifinished product (P) being machined, characterised in that, before, during or after a machining process at least the regions of the planar semifinished product (P) that are to be machined or that have been machined are cooled by a flow of carbon dioxide or of a mixture of carbon dioxide and air, the carbon dioxide being in liquid form and the cooling effect being achieved by means of liquid carbon dioxide being converted to gaseous carbon dioxide.
2. Method according to claim 1, characterised in that a laminar flow of carbon dioxide or of a mixture of carbon dioxide and air is used for cooling (K) one or more regions of the joined planar semifinished product (P).
3. Method according to claim 1, characterised in that a turbulent or pulsed flow of carbon dioxide or of a mixture of carbon dioxide and air is used for cooling (K) one or more regions of the joined planar semifinished product (P).
4. Method according to any of claims 1 to 3, characterised in that the volume flow rate or the flow velocity or the temperature (T) of the flow is adjusted to the optimal temperature or to the optimal temperature profile of the hot-melt adhesive in the joining zone or in the regions of the joined planar semifinished product (P) that are to be machined or that have been machined.
5. Method according to any of the preceding claims, characterised in that the gaseous carbon dioxide, or the mixture of carbon dioxide and air, that is present in the vicinity of the regions of the planar semifinished product (P) after said regions of the planar semifinished product (P) have been cooled (K) is suctioned away.
6. Method according to any of the preceding claims, characterised in that the gaseous carbon dioxide or the mixture of carbon dioxide and air is used for cooling (K) the relevant work station (1-17) or the environment thereof.
7. Device for narrow-surface coating of planar semifinished products or workpieces (P) made of wood material, such as chipboard or medium-density fibreboard, by means of an edge-coating machine or a machining system in which the planar semifinished products (P) that are already coated with two top layers pass in a continuous manner through a plurality of work stations (1-17), the prepared narrow surfaces (120) being bonded to the narrow-surface material (20) that is to be applied, under the effect of pressure and temperature (T) and by means of a hot-melt adhesive that is heated directly or indirectly, and it being possible to machine the narrow surface (120) and the adjacent top layers of the planar semifinished product (P), characterised in that the device comprises means that are suitable for cooling, before, during or after a machining process and by means of a flow of carbon dioxide or of a mixture of carbon dioxide and air, at least the regions of the joined planar semifinished product (P) that are to be machined or that have been machined, the carbon dioxide being in liquid form and the cooling effect being achieved by means of liquid carbon dioxide being converted into gaseous carbon dioxide.
8. Device according to claim 6, characterised in that the means for conducting the liquid or gaseous carbon dioxide or a mixture of carbon dioxide and air is designed as a nozzle that acts at specific points or over an entire surface, as a perforated pressure roller, as a pressure shoe, as an air shower or as an air curtain.
9. Device according to claim 6, characterised in that the liquid or gaseous carbon dioxide, or a mixture of carbon dioxide and air, is conducted through the hollow shaft of a tool as far as the working zone or directly up to the blades.
10. Device according to claim 8, characterised in that the tool is a cutting tool.
11. Device according to claim 6, characterised in that the device comprises means suitable for controlling or regulating the volume flow rate or the flow velocity or the temperature (T) of the flow.
12. Device according to any of claims 6 to 10, characterised in that the device is enclosed and comprises means for suctioning away the gaseous carbon dioxide or the mixture of carbon dioxide and air.
13. Device according to any of claims 6 to 11, characterised in that the device is enclosed and comprises means for suctioning away, recycling and reusing the gaseous carbon dioxide or the mixture of carbon dioxide and air.

Images