EP0325690B1 - Method and stamping tool for the manufacture of a veneer work piece with an outer veneer of wood - Google Patents

Description

The invention relates to a method for producing a veneer workpiece according to the introductory part of claim 1 and a device according to the preamble of claim 15 for its implementation.

From US-A-1,876,330 a method of this type is known, in which the base layer, consisting of a wooden core, together with the wooden veneer are placed in a press punching tool, in which the cover veneer with the base layer is applied using pressure and heat is connected. The parts of the covering veneer that may protrude in the peripheral edge area of the veneer workpiece are cut off in the press-stamping process. Using this known method, only relatively thick veneer workpieces can be produced with sufficient rigidity.

On the other hand, DE-A-3 636 587 (republished) describes a method and a press punching tool of the type mentioned at the outset, which have proven their worth and the production of veneer workpieces with cutouts with significantly less work than until then allow. The cut-out edges are clad with veneer, the procedure being cost-effective and the aesthetic appearance of the veneer workpiece being produced is flawless.

However, it has proven to be desirable to be able to produce veneer workpieces, the surface of which appears to be glossy like a varnish and which, despite the large dimensions and at the same time small overall thickness, are relatively warp-resistant, so that they can also be used for cladding large components. In this regard, the procedure according to DE-A-3 636 587 does not yet guarantee the desired surface quality and can only be used with a limited thickness of the workpiece.

The invention has for its object to further develop the method and the press punching tool of the generic type in such a way that in the single press punching process the veneer workpieces which can be produced can also be produced with a greater thickness than in the prior art described above in a connection-free design, so that they are preferably produced in a straight line , wider contact edges on the possibly concave or convex workpiece z. B. an easy sticking or other attachment to components to be clad is possible; the veneer workpieces should preferably be provided with the desired surface texture, in particular with a matt or high gloss, in the single press stamping process, without the need for reworking.

According to the invention, this object is achieved in a further development of the method of the type mentioned at the outset by the features mentioned in the characterizing part of patent claim 1.

Preferred embodiments of the method according to the invention are the subject of subclaims 6 to 14.

The press punch tool according to the invention is the subject of claims 15 to 22.

The edge compression achieved according to the invention makes it possible to produce extremely torsionally rigid veneer workpieces, such as are advantageous, for example, as lining parts for motor vehicles, in a single press stamping process, in that during compression of the edge area before it is compressed, additional material is "tracked" into the section of the veneer workpiece that is adjacent to the edge area, significantly greater curvatures can be achieved without tearing the top veneer or the veneer layers than was the case with the previously known procedures. Narrow radii of curvature, such as can be realized in the procedure according to the invention, have so far not been achieved. The upsetting of additional veneer layers into the portions of the veneer workpiece to be produced not only has the advantage that the risk of cracks occurring is considerably smaller than in the prior art, but also that very stiff workpieces result.

The contact edges obtained are so dense that they make the penetration of moisture into the veneer workpiece practically impossible without the need for a separate edge seal. Reworking, such as milling or grinding, the contact edges is not necessary. If, as is the case with a preferred embodiment of the invention, a phenolic resin film or the like is arranged on the underside of the veneer workpiece, that is to say on the side facing away from the covering veneer, this serves for additional surface and edge sealing, the one still free of this Edge area is so highly compressed that, as already described, moisture cannot penetrate.

In the press punching tool according to the invention, by means of which veneer workpieces of greater, if of course limited thickness, or greater rigidity than So far known to have been manufactured, either a stationary counter tool and a movable punching tool, for example, or vice versa, and a further pushing tool that is movable in the direction of the punching tool are provided, or the punching tool and the counter tool are designed in the manner according to the invention with interacting circumferential Provide forcing edges or cutting surfaces.

In order to provide the veneer workpieces with a high gloss, two approaches are provided in the invention. Either the lacquer-bearing top veneer of the veneer package is immersed in the lacquer resin, or the surface material is applied as a lacquer film. The veneers for the cover veneer must always be sanded as a single part before treatment with the surface material or before the press stamping process with a low grain size of the grinding material adapted to the surface sanding, since surface treatment on the finished, pressed molded part is only possible with a great deal of time. In the first-mentioned procedure according to the invention, the cover veneer is first immersed in a corresponding lacquer resin solution. The dipping process is followed by a drying process, which continues until the moisture content of the wood is no more than 6%. After the drying process has been completed, the veneer package is gathered and inserted into the molding press, i.e. the press stamping tool. The pressing surface of the press punching tool facing the cover veneer is preferably hard chrome-plated, glossy, but with a desired matt glossy surface matt, depending on the degree of gloss to be achieved of the surface of the veneer workpiece.

In the other embodiment of the method according to the invention, in which the desired glossy or matt-gloss surface is produced using the film coating method, the procedure is particularly simple and time-saving. The lacquer film is cut and then placed on the top veneer sheet of the veneer package, whereupon the entire veneer package with the lacquer film is then inserted into the press. No further treatment of the veneer package takes place; rather, in both processes the veneer workpiece leaves the press stamping tool or the molding press as a finished surface-treated end product.

It is particularly advantageous here that no post-treatment of the cover veneer surface, which is usually required after the compression molding process, by grinding etc., is more necessary, rather the corresponding processing operations in both cases can be carried out completely before the compression molding process on the still flat cover veneer sheet .

The parameters for the pressing process, namely temperature, pressing pressure and pressing time, are preferably those also used in the procedure according to DE 36 36 587 A1, although the special processing conditions of the paint resin or paint film used may have to be observed. Overall, the method according to the invention can be used analogously with the corresponding parameters of DE 36 36 587 A1, both with regard to the method steps and the structure of the press-punching tool, so that the disclosure content of DE 36 36 is fully applicable to supplement the inventive concept in this regard 587 A1 in the Invention is included.

Compared to the previously used working method for achieving shiny surfaces with its numerous work processes, the method according to the invention is very little time-consuming and also very economical

Fig. 1

ein erstes Ausführungsbeispiel eines Preßstanzwerkzeuges nach der Erfindung im Schnitt senkrecht zur Hauptebene des damit herstellbaren Furnierwerkstückes, in leerem Zustand, wobei das Stanzwerkzeug und das Gegenwerkzeug die Schließstellung einnehmen, während das Abdrückwerkzeug sich in der Offenstellung befindet;

Fig. 2

das Preßstanzwerkzeug von Fig. 1 mit eingelegtem Furniermaterial in der dort beschriebenen Stellung der Einzelwerkzeuge, in in bezug auf die Dicke des Enderzeugnisses etwas vergrößerter Darstellung;

Fig. 3

das Preßstanzwerkzeug von Fig. 1 und 2 im Endzustand, wobei auch das Abdrückwerkzeug seine Schließstellung erreicht hat; und

Fig. 4

im Schnitt senkrecht zur Hauptebene in stark vergrößerter Darstellung den Randbereich eines nach dem erfindungsgemäßen Verfahren hergestellten Furnierwerkstückes.

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:

Fig. 1

a first embodiment of a press punching tool according to the invention in section perpendicular to the main plane of the veneer workpiece that can be produced therewith, in an empty state, the punching tool and the counter tool occupying the closed position while the pressing tool is in the open position;

Fig. 2

the press punch tool of Figure 1 with inserted veneer material in the position of the individual tools described there, in relation to the thickness of the finished product somewhat enlarged.

Fig. 3

the press punch tool of Figures 1 and 2 in the final state, wherein the pressing tool has reached its closed position. and

Fig. 4

in section perpendicular to the main plane in a greatly enlarged representation the edge area of a veneer workpiece produced by the method according to the invention.

As can be seen in FIG. 1, the press punching tool according to the invention has, in the exemplary embodiment shown there, a movable punching tool 12, a counter tool 14 and a pressing tool 15. The punching tool 12 is provided with a displacement surface 16 and the pressing tool 15 is provided with a pressing surface 17. The displacement surface 16 of the punch 12 adjoins a cutting edge 18. The pressing tool 15 can be moved in the direction of the arrow 19. A shaping surface 20 adjoins the cutting edge 18 of the punching tool 12, which corresponds to a complementary counter tool shaping surface 21 on the counter tool 14. This and the pressing surface 22 of the stamping tool 12 are hard chrome-plated high-gloss.

A bent surface 23 adjoins the shaped surface 21 of the counter tool 14. In special cases, this kink surface can also be inclined outwards, so that the lower surface of the edge compaction is not a horizontal one. The veneer package for the veneer workpiece to be produced has a layering of base veneer layers 32 and a top veneer layer 34 made of wood. FIG. 2 furthermore shows a displacement quantity 35, the veneer material used for the production of the edge compression, residual pieces and edge waste or residual pieces 36, the meaning of which will be explained further below. The real thickness of the pressed veneer package is indicated with "37", while the delimitation of the waste 35 to be displaced is shown in dash-dot lines with "38". A waste space 39 is located between the pressing tool 15 and the punching tool 12, while finally FIG. 3 shows a lower end 40 of the veneer package, namely the edge compression produced.

The method according to the invention can be carried out by means of the press punching tool described above in a preferred exemplary embodiment as follows, it being pointed out that in the representation according to FIG. 2 in the sense of the representation of the material displacement with respect to the bending and kinking of the hand area of the veneer layers, the pressing pressure does not yet act on the veneer layers, but rather the punching tool 12 and the counter-tool 14 are moved together only to such an extent that the edge area of the veneer layers is bent or kinked, while the full pressing pressure acts on the veneer layers only in the manner of representation according to FIG. 3:
The veneer package, which is only roughly cut to size, in which the veneer layering with the base veneers 32, possibly also with the phenolic resin film 48 serving as a base, and the cover veneer 34 essentially corresponds to DE 36 36 587 A1, is placed on the lower counter tool 14, after a lacquer resin film may have been placed on the top veneer 34 beforehand. Then the punch 12 lowers on the veneer package and compresses it to the required veneer workpiece thickness 37. The edge waste parts 36 projecting beyond the finished dimension cannot hang freely down into the waste space 39, but are bent over by the kink surface 23 in the direction of the waste space 39. The unnecessary edge waste pieces are then cut off by the pushing tool 15 moving upward in the direction of arrow 19 with a delay against the lowering of the punching tool 12 with the aid of the cutting edge 18, in cooperation with the pushing surface 17, and fall into the waste space 39 the dash-dotted lines 38 limited displacement 35 is pushed up by the push-off tool 15 into the lower end 40 (FIG. 3) of the veneer package 40 and displaced there in the mass with compression of the entire edge area and stiffening. This is a particularly important feature of the invention, since in this way support edges or edge reinforcements with pre-strength can be obtained, as are particularly advantageous when veneer workpieces of the type produced according to the invention are to be used, for example, for gluing to the interior of motor vehicles or the like.

In the invention, a press stamping tool can also be used, in which the stamping tool 12, following the molding surface 21, has a circumferential cutting surface which merges smoothly therein, to which the displacement surface 16, which is likewise substantially uniform and merges therein, connects. In contrast to the exemplary embodiment according to FIGS. 1 to 3, in which the kink surface is essentially parallel to the main plane of the veneer workpiece which runs horizontally in the drawing, the kink surface 23 extends obliquely downward in the press punching tool thus designed in the direction of a circumferential pressing edge the counter tool 15, whereby on the kink surface 23 on the opposite side of the push-off edge there is a constriction which makes it possible to accommodate the displaced and cut-off edge material in the waste space provided here as well.

The press punch of the modified type described above works in such a way that when the punch 12 and the counter tool 14 approach each other, the nose-like formation of the pressing edge continuously pushes further material into the edge area of the veneer workpiece to be produced into the punch 12, so that it cannot form cracks on the shaped surface 21 even in the case of severe curvatures. Ultimately, the push-off edge then comes into cutting contact with the circumferential cutting surface, as a result of which the edge material is separated with final edge compression, which then falls into the waste space 39.

4 shows the edge area of a veneer workpiece to be produced according to the invention: As can be seen there, an edge compression 50 has a cover on the one hand by the cover veneer 34, and on the other hand by a phenolic resin film 48, so that due to the high compression in the Both exposed edge areas nevertheless ensure a high level of security against the ingress of water into the veneer workpiece.

In addition, because of the temperatures to be used, the pressures, etc., in the method according to the invention, reference is also made to the relevant explanations in DE-A 36 36 587.

Claims (22)

1. A method of producing a veneer article in the form of a substantially flat or plane or curved sheet or the like, with a base layer and a wood covering veneer layer, the base layer and covering veneer being glued together in a single pressing and punching step to form a strong workpiece, characterised in that at least some of the peripheral edge zone of the veneer workpiece is bent round and compacted near the edge to produce an edge reinforcement.
2. A method according to claim 1, characterised in that a base layer consisting at least to some extent of wood is used.
3. A method according to claim 1 or 2, characterised in that a laminated base veneer comprising a number of discrete layers is used as base layer.
4. A method according to any of the previous claims, characterised in that the base layer and the covering veneer are glued together by means of a synthetic resin adhesive.
5. A method according to any of the previous claims, characterised in that the base layer and the covering veneer are formed in the pressing and punching step with a cut-out which extends through them, the covering veneer layer being pressed through in the pressing and punching step from the surface of the veneer article into the cut-out, covering the peripheral wall thereof, as far as the bottom edge of the cut-out.
6. A method according to any of the previous claims, characterised in that the bending round is effected towards that side of the veneer article which is remote from the covering veneer.
7. A method according to any of the previous claims, characterised in that the bending round is effected at approximately 90° to the main plane of the veneer article.
8. A method according to any of the previous claims, characterised in that the covering veneer covers the edge reinforcement or the cut-out surfaces substantially completely as far as a contact surface which extends substantially parallel to the main plane of the veneer article.
9. A method according to any of the previous claims, characterised in that substantially the entire periphery of the article or of the cut-out therein is covered by the edge reinforcement or covering veneer.
10. A method according to any of the previous claims, characterised in that the edge compacting is produced with bending down of some of the edge zone of the veneer group or packet and upon termination of the pressing and punching step a projecting edge waste residue is severed.
11. A method according to any of the previous claims, characterised in that the covering veneer is provided with a lustrous paint surface in the pressing and punching step.
12. A method according to claim 11, characterised in that the covering veneer is impregnated with a synthetic resin paint before the veneer group or packet is brought together, then dried and finally subjected to the pressing and punching step with the other veneer layers with the use of a lustrous pressing surface.
13. A method according to claim 11, characterised in that before the pressing and punching step a film of a synthetic resin paint is applied to the surface of the veneer group when the same has been joined together including the covering veneer, whereafter the pressing and punching step is performed with the use of a lustrous pressing surface.
14. A method according to any of the previous claims, characterised in that that surface of the base layer which is remote from the covering veneer is pressed at least in zones together with a phenol resin film.
15. A pressing and punching tool for performing the method according to any of the previous claims and having a punching tool and a companion tool or die each having a pressing surface, the punching tool (12) having a peripheral cutting facility (18) with associated displacing surface (16) and a shaping or moulding surface (20), characterised in that the companion tool or die (14) has: a peripheral shaping or moulding surface (21) associated with the shaping or moulding surface (20) of the punching tool; and a bending surface or step (23) into which the surface (21) merges.
16. A pressing and punching tool according to claim 15, characterised in that the peripheral cutting facility has a peripheral cutting edge (18), with the pressing and cutting tool in the closed state the peripheral cutting edge (18) is at a reduced distance from the peripheral edge of the bending surface or step (23) - i..e., from the surface of the die - and a pressing-off tool (15) is associated with the die (14) and by a movement towards the punching tool (12) can be brought into engagement therewith with the simultaneous production of an edge reinforcement by some of the pressed-off surplus veneer material being pressed into the gap between the cutting edge (18) and the peripheral edge of the bending surface or step (23) with the cutting edge to sever projecting waste material.
17. A pressing and punching tool according to claim 16, characterised in that the bending surface (23) extends substantially parallel to the main plane of the veneer article.
18. A pressing and punching tool according to claim 16 or 17, characterised in that the displacing surface (16) is disposed on that side of the peripheral cutting edge (18) which is remote from the shaping surface (20).
19. A pressing and punching tool according to claim 15, characterised in that the peripheral cutting facility has a peripheral cutting surface which merges substantially flatly and uniformly into the shaping surface (20) on one side and into the displacing surface (16) on the other and widens substantially inclinedly towards the die (14), and the bending surface or step (23) has on its outer periphery a pressing-off edge which with the pressing and punching tool closed is in cutting contact with the peripheral cutting surface.
20. A pressing and punching tool according to claim 19, characterised in that the bending surface or step (23) inclines substantially diagonally outwardly towards the pressing-off edge so that the bottom peripheral article edge has the shape shown in Fig. 4.
21. A pressing and punching tool according to claim 19 or 20, characterised in that the die (14) has a restriction on that side of the pressing-off edge which is remote from the bending surface or step (23).
22. A pressing and punching tool according to any of claims 15 to 21, characterised by a waste collecting space or chamber (39) which is adapted to receive the severed edge waste (36) and which is bounded by the die (14) and the punching tool (12).

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