EP0265632A2 - Method and stamping tool for the manufacture of a veneer work piece with a cutout - Google Patents

Abstract

A process for producing a veneer workpiece in the form of a flat plate or the like with a base layer, preferably consisting at least partially of wood, optionally layered as a base veneer from a plurality of individual layers, a cover veneer having at least one cover veneer layer made of wood, and a cutout penetrating the base layer and the cover veneer which the base layer and the cover veneer are preferably glued together using synthetic resin adhesive, the cutout (s) penetrating the base layer and the cover veneer and finally its peripheral wall (s) is / are covered with cover veneer material, characterized in that the gluing of the base layer and the cover veneer to a solid workpiece, the formation of the cutout (s) and the covering of the peripheral wall of the same with the cover veneer take place in a single press-stamping operation, the cover veneer layer being separated from the surface of the veneer piece is pressed into the cutout (s) while cladding the peripheral wall thereof up to the cutout edge defining the transition of the peripheral wall with the opposite surface of the veneer workpiece.

Description

The invention relates to a method for producing a veneer workpiece in the form of a flat plate or the like with a base layer, preferably consisting at least partially of wood, optionally layered as a base veneer from a plurality of individual layers, a cover veneer having at least one cover veneer layer made of wood, and a base layer and the cover veneer penetrating cutout, in which the base layer and the cover veneer are preferably glued to one another using synthetic resin adhesive, the cutout (s) penetrating the base layer and the cover veneer and finally the peripheral wall (s) thereof is / are covered with cover veneer material.

The manufacture of furniture or other wooden parts with cutouts, the edges of which are provided with the material of the veneer of the veneer workpiece concerned, has so far been carried out in the following way: the workpiece is veneered with the veneer of the corresponding type of wood, the cutout is milled out, and the edges of the Cutouts are glued with cover veneer strips that are slightly larger in width than the thickness of the workpiece. The side edges of the glued cover veneer strips covering the peripheral wall of the cutout in question stand on both sides beyond the surface of the workpiece after gluing and must be cut away in a special operation, whereupon the cutout edges must be plastered. The following operations are therefore required: Manufacture of the workpiece by gluing from cover veneer and the corresponding base or middle layer veneers, milling the cutout, sharply filing out the cutout corners, since milling corners always have roundings, depending on the cutter diameter, with a more or less large radius of curvature, cutting to size the cover veneer strips to length, cut to size, glue the cover veneer strips to the circumferential wall of the cutouts, deburr the edges of the cover veneer strips that protrude beyond the side surfaces, and finally plastering or sanding the glue joints. As a result of the steps described above, the known method of the generic type is very labor-intensive, and the aesthetic effect of the cutouts produced in this way and clad with covering veneer material in their peripheral walls also leaves something to be desired.

The invention is therefore based on the object of providing a method and a press punching tool of the generic type in which the amount of work is considerably less than previously, the procedure is inexpensive and the aesthetic appearance of the veneer workpiece produced is flawless.

According to the invention, this object is achieved in a method of the generic type in that the gluing of the base layer and the cover veneer to a solid workpiece, the formation of the cutout (s) and the cladding of the peripheral wall of the same with the cover veneer in a single press stamping operation take place, the covering veneer layer is pressed from the surface of the veneer workpiece into the cutout (s) while cladding the peripheral wall of the same up to the cutting edge defining the transition of the peripheral wall with the opposite surface of the veneer workpiece.

It can be provided that the press stamping process is carried out at a temperature of about 140 ° C.

It can also be provided that phenolic resin film is used to glue the veneer layers.

Furthermore, the invention proposes in the particular embodiment of the claimed method that synthetic resin glue is used to glue the veneer layers.

It can also be done in such a way that the pressing process is carried out with a pressing pressure of approx. 10 kp / cm².

The press punching tool proposed according to the invention for carrying out the claimed method is characterized by a punching tool which is provided with at least one cutting edge with an associated displacement surface and an associated shaping surface for producing cutouts, and an essentially flat counter-tool in the form of an essentially flat plate.

It is preferably provided that the punching tool and / or the counter tool is / are designed to be heatable.

Furthermore, it can be provided that the counter tool as the lower tool is arranged substantially horizontally in a stationary manner and the punching tool as the upper tool is designed such that it can be moved relative to it.

A further embodiment of the press punching tool according to the invention is characterized by at least one spacing surface provided on the punching tool to prevent the cutting edge (s) of the punching tool from coming into contact with the surface of the counter tool.

It can be provided that the punch has a shaped edge near the outer edge of the veneer workpiece to be produced.

Furthermore, the shaped edge in the press punching tool according to the invention is preferably rounded.

Finally, a further embodiment of the invention proposes a press stamping tool, which is characterized in that the distance of the molding edge from the surface of the counter tool in the closed state of the press stamping tool is greater than the distance of the cutting edge (s) from the surface.

In contrast to the prior art, veneer workpieces with cutouts, the peripheral wall of which is veneered, can be produced according to the invention, in which the gluing of the workpiece from individual layers and the cutting of the cutout with the subsequent veneers of the peripheral wall of the cutout takes place in a single press-stamping process. Instead of the seven operations that were necessary in the previous procedure, only a single press stamping operation is required. The invention offers numerous advantages: the method according to the invention is simple to carry out, since only a single operation is required; the lead time through the production is therefore very short; in a single operation, a cleanly manufactured veneer workpiece is delivered, which does not require rework; the procedure according to the invention is material-saving, since no cover veneer strips are required as edge veneers and also no glue required to glue the same; the method according to the invention is extremely labor-saving in that it replaces the seven operations required in the prior art by a single combined press-stamping operation, already carried out; the veneer workpiece according to the invention is inexpensive to manufacture, since the effort for wage and ancillary wage costs is low; the method according to the invention saves investment and space by only occupies a workstation with a hydraulic press for the press punching tool; and finally, the insertion of fastening parts can be integrated into the press stamping operation, for example on the flat back of the veneer workpiece facing the counter-tool, for example according to the teaching of DE-GM 78 23 688.

For workpieces of limited thickness, for example up to a thickness of five mm, as e.g. occur as edging of scales on the front of devices, with a press stamping process according to the invention when producing the veneer workpiece from its layers, simultaneously with the pressing and punching of the cutout, the cover veneer of the viewing surface is pulled down into the depth of the cutout to the boundary edge with the rear surface, as already explained, so that the peripheral wall of the cutout is covered with veneer and this receives a sharply formed cutout edge by displacing the veneer layers in the lower part of the cutout edge. This eliminates all other cleaning work required at this point. There is also no need for any work with the covering veneer strips required in the prior art, and these themselves, including the adhesive required for gluing, which means that the procedure according to the invention is very little labor-intensive and also saves material.

In the case of cambered parts, the underside of the veneer workpiece to be produced is always flat by being pressed onto the surface of the lower tool, so that the veneer workpiece can be glued on without further preparatory work, for example milling a support surface. With face milling, as has been necessary up to now, the veneer workpieces can also warp slightly because the counter veneers are partially destroyed and unilateral tensile forces can occur.

The press punching according to the invention and the pulling in of the cover veneer down to the cut-out edges succeed the easier the larger the radius of curvature of the peripheral wall of the cut-out, since the elasticity of the wood from which the cover veneer is made is proportionate both lengthways and transversely to the grain of the wood is low. According to the invention, however, the need to achieve the sharpest possible cut edges, because round cut edges can cover parts of any tables, scales, etc. to be framed, can be largely met, since the method according to the invention enables the technically flawless production of sharp cut edges very economically, which makes the aesthetic Requirements for cutouts in surfaces can be met to a far greater extent than is the case with the prior art.

• Fig. 1 ein Stanzwerkzeug einer Vorrichtung nach der Erfindung, als Oberwerkzeug ausgebildet, im Schnitt senkrecht zur Ebene des herzu­stellenden Furnierwerkstückes;
• Fig. 2 im Schnitt entsprechend Fig. 1 ein als Unter­werkzeug ausgebildetes Gegenwerkzeug einer Vorrichtung nach der Erfindung;
• Fig. 3 in vergrößertem Maßstab Stanz- und Gegen­werkzeug im Schnitt entsprechend Fig. 1 und 2 mit Detaildarstellung der Formungs- und Schneidstellen; und
• Fig. 4 in vergrößerter Schnittdarstellung, ent­sprechend Fig. 1 bis 3, den Schneid- und Verdrängungsvorgang bei der Verwendung des Stanzwerkzeuges gemäß Fig. 1 - Fig. 3.

Further features and advantages of the invention result from the description below, in which exemplary embodiments are explained in detail with reference to the schematic drawing. It shows:

• 1 shows a punching tool of a device according to the invention, designed as an upper tool, in section perpendicular to the plane of the veneer workpiece to be produced;
• FIG. 2 in section corresponding to FIG. 1, a counter tool of a device according to the invention designed as a lower tool;
• Fig. 3 on an enlarged scale punching and counter tool in section corresponding to Figures 1 and 2 with a detailed representation of the forming and cutting points. and
• 4 in an enlarged sectional view, corresponding to FIGS. 1 to 3, the cutting and displacement process when using the punching tool according to FIGS. 1-3.

As can be seen in FIG. 1, a stamping tool 12 shown there, designed as the upper tool of the press stamping tool forming the device according to the invention, has a conical jacket-shaped displacement surface on its lower surface in FIG. 1, facing a counter tool 14 shown in FIG 16 which, on its side facing the counter tool 14, ends in a cutting edge 18 which is circular in the exemplary embodiment shown. From the cutting edge 18, a curved shaped surface 20, bent into a four-part circle, rises to a pressing surface 22, which runs essentially parallel to the surface of the genetic tool 14. Within the area of the cutout to be produced in the veneer workpiece to be produced, which is surrounded by the cutting edge 18, an evasive surface 24 set back with respect to the pressing surface 22 can be seen. FIG. 2 also shows that the surface 26 of the counter tool 14 facing the punching tool 12 is flat. Finally, near the left edge of the punch 12, FIG. 1 shows a shaped edge 28 with rounded surfaces, which does not come into contact with the surface 26 of the punch 14 when the punch 12 and counter tool 14 move together, so that the drawing of veneer material in the direction is not hindered on the cutout to be produced.

In the exemplary embodiment of FIG. 3, the punching tool 12 has a number of cutting edges 18, etc. for producing several cutouts. Furthermore, Fig. 3 shows that the punch 12 is provided with a spacer 30, which comes into contact with the surface 26 of the punch 14 when the punch 12 and counter tool 14 move together and prevents the cutting edges 18 of the punch 12 from contacting the surface 26 of the counter tool 14 come into contact and could be damaged as a result, the distance between the cutting edges 18 and the surface 26 of the counter-tool 14 being only a few hundredths of a millimeter when the spacing surface 30 abuts the surface 26.

Fig. 4 finally shows how base veneer layers 32 and a dashed veneer layer 34 of the veneer tool are deformed when the punching tool 12 and counter-tool 14 move together, the veneer layer 34 covering the entire circumferential wall of the cutout and up to that Gengenwerkzeug 14 facing flat rear surface of the veneer workpiece to be produced extends.

The device described above works as follows when carrying out the method according to the invention for producing the veneer workpiece according to the invention:

The upper tool, ie the punching tool 12, is used for shaping and cutting and has the cutting and squeezing edges in the form of the cutting edges 18 for the removal of the waste piece filling the cutout and the displacement of the material at the cutting edges. Furthermore, the punching tool 12 also has the shaped edge 28 on its outer edge in the manner described, by means of which a rounded outer edge can also be formed there if necessary. As already stated, the shaped edge 28 does not, however, extend to the surface 26 of the counter-tool 14 in the closed state of the press-punching tool and also has no sharp cut surfaces on its side facing the surface 26, rather the shaped edge 28 is rounded so that the top veneer layer 34 of the Veneer workpiece that occurs when molding in the direction of the cutting edges 18 Tensile stress is not a hindrance.

The fact that the distance surface 30 to the surface 26 of the counter-tool 14 has such a distance that the cutting edges 18 of the punch 12 come within a few hundredths of a millimeter of the surface 26 of the counter-tool 14 when the press punch tool is closed, ensures that the cutting edges 18 Cut the material of the veneer layers 32 and 34, which form the cutout waste, to such an extent that the piece of waste, which in the state still consists of loose veneer sheets, falls out and a sharp boundary edge is created on the inner edge of the cutout produced.

Both parts of the press stamping tool, that is to say both the stamping tool 12 and the counter tool 14, are heated, the heating temperature being in the range of approximately 140 ° C. in the preferred method of working with a phenolic resin glue film. At this temperature, the phenolic resin changes into a liquid phase, as a result of which the slidability of the individual layers required when shaping and warping the top veneer layer 34 and partly the base veneer layers 32 is achieved. The required pressure, which is sufficient for the bonding of the individual layers, the cutting pressure and the displacement pressures that are required at the cutting edge of the cutout, is preferably approximately 8 to 10 kp / cm².

The method according to the invention represents a combined gluing and press stamping process. The procedure is as follows: Since the workpiece consists of individual layers of veneer, as first the layering from the base veneer layers 32 and the top veneer layer 34 is gathered and placed on the surface 26 of the counter tool 14. The press punching process is then initiated in that the upper punch tool 12 approaches the lower counter tool 14. As it goes down, the cutting edge 18 detaches the piece of waste from the cutout and presses the edges of the workpiece to be shaped down with the shaped surfaces 20 and the displacement surfaces 16. This begins the displacement process against the workpiece material at the cut edges of the workpiece, which increases the further the cutting edges 18 of the punching tool 12 approach the surface 16, serving as a support surface, of the lower counter tool 14. The deformation and displacement pressure on the cut-out edges is accompanied by a tensile effect on the wood surface of the top veneer layer 34 and partly also on the adjacent layers of the base veneer layers 32 and pulls these, which have become slidable due to the dissolved phenolic resin in the phenolic resin film, to the lower boundary edge of the Cutout down so that the cover veneer layer 34 pressed down by the deformation pressure forms a sharp, hard boundary edge on the surface facing the surface 26 of the counter tool 14, which does not require any further processing, for example by milling. As practice shows, the tensile effect is sufficient to pull the cover veneer layer 34 down to the lower boundary edge of the cutout facing the surface 26 and thus completely cover the peripheral wall of the cutout, including the shape or limit edge, with the cover veneer. Since the tensile effect that can be achieved is limited, this work technique is limited with regard to the workpiece thickness, which is approximately 5 mm overall thickness of the veneer workpiece to be produced. Smaller cracks, which rarely occur, are caused by the displacement pressure closed. With the progressive lowering of the punching tool 12 onto the counter tool 14, the closing of the tools begins, the pressing pressure which is exerted on the workpiece surfaces reaching its end point and the layering of the veneers in conjunction with the pressing temperature for setting with the phenolic resin, thereby bringing about this firmly bonded veneer workpiece is made.

There are practically no limits to the size and shape of the cutouts to be made. Cut-out edges with a larger radius of curvature and with a smaller radius of curvature are possible. In the case of cambered parts, the underside can be pressed out flat, so that the veneer workpiece can be glued on without a special operation.

The features of the invention disclosed in the above description, in the drawing and in the claims can be essential both individually and in any combination for realizing the invention in its various embodiments.

Reference symbol list

• 12 punching tool
• 14 counter tool
• 16 displacement surface
• 18 cutting edge
• 20 shaped surface
• 22 pressing surface
• 24 alternative area
• 26 surface
• 28 shaped edge
• 30 distance surface
• 32 Basic layer of veneer
• 34 face veneer

Claims (12)

1. A method for producing a veneer workpiece in the form of a flat plate or the like with a base layer preferably consisting at least partially of wood, optionally layered as a base veneer from several individual layers, a cover veneer having at least one cover veneer layer made of wood and a cutout penetrating the base layer and the cover veneer , in which the base layer and the cover veneer are preferably glued to one another using synthetic resin adhesive, the cutout (s) penetrating the base layer and the cover veneer and finally its peripheral wall (s) being covered with cover veneer material that the gluing of the base layer and the cover veneer to a solid workpiece, the formation of the cutout (es) and the cladding of the peripheral wall of the same with the cover veneer take place in a single press stamping operation, the cover veneer layer being separated from the surface of the furnace is pressed into the cutout (s) while cladding the peripheral wall of the same up to the cutout edge defining the transition of the peripheral wall with the opposite surface of the veneer workpiece. 2. The method according to claim 1, characterized in that the press stamping process is carried out at a temperature of about 140 ° C. 3. The method according to claim 1 or 2, characterized in that phenolic resin film is used for gluing the veneer layers. 4. The method according to claim 1 or 2, characterized in that synthetic resin glue is used for gluing the veneer layers. 5. The method according to any one of the preceding claims, characterized in that the pressing process is carried out with a pressing pressure of about 10 kp / cm². 6. Press punching tool for carrying out the method according to one of the preceding claims, characterized by a punching tool (12) which is provided with at least one cutting edge (18) with an associated displacement surface (16) and associated shaping surface (20) for producing cutouts, and essentially flat counter tool (14) in the form of a substantially flat plate. 7. Press punching tool according to claim 6, characterized in that the punching tool (12) and / or the counter tool (14) is / are heatable. 8. Press punching tool according to claim 6 or 7, characterized in that the counter tool (14) is arranged as a lower tool substantially horizontally stationary and the punching tool (12) is designed to be movable in height relative thereto as an upper tool. 9. Press punch according to one of claims 6 to 8, characterized by at least one on the punch (12) provided spacer (30) for preventing the cutting edge (s) (18) of the punch (12) from coming into contact with the surface (26) of the counter tool (14). 10. Press punching tool according to one of claims 6 to 9, characterized in that the punching tool (12) has a shaped edge (28) near the outer edge of the veneer workpiece to be produced. 11. Press punching tool according to claim 10, characterized in that the shaped edge (28) is rounded. 12. Press punch tool according to claim 10 or 11, characterized in that the distance of the molding edge (28) from the surface (26) of the counter tool (14) in the closed state of the press punch tool is greater than the distance of the cutting edge (s) (18) from the surface (26).

Images