US2245170A - Method of producing veneers - Google Patents

Description

June 10, 1941. E. F. VON ENDELETAL 2,245,170

METHOD OF PRODUCING VENEERS Filed- Aug. 18, 1937 Helrlrv ch Geffcken Patented June 10, 1941 2,245,170 7 METHOD or PRODUCING VENEERS Emil Freiherr von Ende, Haslach I./K., and Heinrich Geffcken, Berlin, Germany Application August 18, 1937, Serial No.'159,734

In Germany March 6, 1937 3 Claims.

The present invention relates to improvements in artificially veined veneers and a method of making the same, more particularly to veneers of the type obtained by gluing together under heat a plurality of superposed ordinary veneers in a press having profiled, such as corrugated, dies, and by subsequently cutting up the composite block thus -obtained into new. veneers along cutting lines intersecting the initial veneers in the block.

In carrying out, the aforedescribed method, difficulties have been encountered in that the fibres in the finished veneer were torn or splintered or the veneer easily broken or cracked. Moreover, if the veneer thus obtained was glued npona base, the glue easily penetrated through the veneer, producing stains and-spoiling the polish thereon.

By the present invention the above drawbacks are substantially overcome by the employment of special veneers for producing the intermediate blocks in the manufacturing process and a novel compressing operation in forming the composite intermediate block from which the final veneers are cut.

With this and other objects in view, the invention contemplates the use of so-called paredoff veneers obtained by spirally cutting a trunk from the outside to the inside in place .of the usual veneers obtained by transverse cutting or sawing in planes more or less parallel to the axis of the trunk. A block or stack of pared-off veneers of this type is then subjected to pressure, preferably in such a manner that the pressure is applied at first to one side only of the stack and gradually increased and extended until covering the entire stack area. It was found in carrying out the above processthat pared-01f veneers are better able to stand the tensile and compressive forces exerted thereon during compression, thereby preventing tearing or breaking as experienced with the ordinary type of veneer used in the prior art processes. Moreover, pared-off veneers have the advantage of gliding upon one another more easily and smoothly if subjected to pressure'in a press with profiled dies thereby enabling them to become deformed more easily and to conform and accommodate themselves to the shape of the pressing dies without tearing or splintering. These properties are apparently due to the'fact that adjacent c lls or fibres in pared-off or spirally cut veneers belong to the same period of growth (armual rings) while in the case of transversely cut veneers cells of successive periods of growth having dilferent mechanical properties lie side by side.

The above and further objects and advantages of the invention will become more apparent from the following detailed description of a method and means for carrying out the invention taken with reference to the accompanying drawing forming part of this specification and wherein:

- Figure 1 shows for the sake of illustration the production of spirallycut or pared-off veneers.

for use with the invention;

Figures 2 and 3 illustrate diagrammatically pressing devices suitable for carrying out the invention;

Figure 4 is a partial section on an enlarged scale of a compressed block of veneers ready for cutting into final veneers;

Figure 5'illustrates a surface pattern of a veneer obtained by the invention;

Figure 6 shows a plurality of veneers stacked before compressing according to a modification of the invention; v

Figure '7 illustrates another modification of the invention; and

Figure 8 shows the surface of a finished veneer obtained by the modified processes according to Figures G and 7.

Similar reference numerals identify similar parts throughout the different views of the drawing.

Referring to Figure 1, this illustrates the cutting or paring off of a veneer sheet from a trunk rings of a trunk pertaining to the same period of growth and having substantially uniform mechanical and other properties.

A veneer sheet obtained in this manner is cut into suitable elements which may be freed from 'moisture and subjected to the action of a mordant in the usual manner and/or dyed if desired and are then surfaced with a gluing substance. The elements or sheets thus prepared are then piled upon each other to form a stack and the stack placed in a press of the type as shown in Figure 2. The latter consists of a frame 3 carrying a lower plate or block 4 having secured'thereto a die 6 formed with a profiled, such as a corrugated, face as shown in the example illustrated. The press further comprises an upper block 5 with a die 8 having a similar profile or cross-section to the die 6 *of the lower pressing block. The stack 1 of veis placed upon the lower die 6 and the upper. section moved in a downward direction indicated by the arrow II in a manner well understood.

There is further shown a wedge-like member 9 of rubber or other yielding material placed between the upper face of the stack and the adjacent upper die plate 8. In the drawing the thickness of the member 9 has been shown on an exaggerated scale for clarity ,of illustration. There is furthermore provided a suitable heating system or furnace indicated at I surrounding the die sections and block I placed therebetween.

In carrying out the pressing operation; the block I is at first heated to a suitable temperature, whereupon the press is closed to apply increasing pressure to the stack. The effect of the wedge-shaped rubber member 9 is to cause the pressure to be initially applied to the block 1 at the left-hand side only of the stack area and to extend gradually over the entire face of the block or stack as the die 8 is moved towards the stacks and the pressure increased. Owing to the pliableness of the pared-01f veneers in the stack 1 and to they uniform properties of the cells or fibres within the individual veneers, the

. latter will ofier relatively small resistance and glide easily and smoothly upon one another during the pressing operation thereby conforming and accommodating themselves readily to the shape of the dies 6 and]. After the compression the temperature. is suitably adjusted and the block allowed to set and thereafter to cool in the press.

Figure 3 shows a modified arrangement of a press wherein the wedge-shaped resilient member I3 is placed between the die member I! and the upper section or block 5. This arrangement has the advantage that the plate I! may be protected against excessive heat by cooling the die 5. It is furthermore possible by this arrangement to lift the die 5 after the block has been preliminarily compressed to remove the wedge 13 and thereafter to re-compress the stack in order to preserve the wedge l3 and prevent it from being subjected to excessive and prolonged heating. A further advantage is the fact that in this manner the wedge I; can be more easily removed from the stack and is not affected by or soiled with glue as in the case of the arrangement shown in Figure 2.

Figure 4 shows on an enlarged cross-section, a portion of a finished veneer block obtained after gluing and compressing in the manner described hereinbefore. This block is then cut into new veneers along parallel lines as indicated by a:11

' intersecting the 'initial veneers whereby the veneers obtained in this manner exhibit artificial veins such as shown in Figure 5. These veins will be especially impressive if the individual veneer sheets in the block '1 originated from different kinds of wood or are tainted with different colors and are arranged in suitable succession within the block.

The veneers made in the above-described manner are generally free from knot holes. In most cases this constitutes an advantage but there are cases where a knot hole or"birds-eye appearance of the final veneer is desired. This can be obtained in a simple and easy manner in the manufacture of artificial veneers in'accordance with-the process of the present invention such as described in the following with reference to Fig-' ures 6 and 8.

In Figure 6 there is shown a stack 1 of veneers prior to compression with wooden bead ll pletely embedded in the veneer block during the compressing operation. By cutting such a block in the manner described, final veneers are obtained having an appearance with bird's-eye efiects as shown in Figure 8 similar to the patterns characteristic of certain natural knotty or curly woods. In the making of veneers of this type, the press is preferably designed in such a manner that the profiled dies 6 and 8 fit into each other exactly such as in the case of corruga'ted dye blocks as shown in Figure 2.

A similar effect may be obtained by preliminarily producing blocks of corrugated veneers of substantially smaller thickness, perforating the same, and driving wooden pegs into the perforations to hold the blocks together as shown in Figure 7.' A plurality of such blocks may-then be piled upon one another and glued together and compressed to form a larger block in the manner as will be understood from the above. Preferably the temperature during the second compressing operation in uniting the preformed blocks is higher than the temperature employed in forming the initial blocks. The preliminary pressing of the smaller blocks into the final corrugated shape of the sheets as shown in Figure I has the effect to prevent tearing the sheets when drivingthe peg I6 into the perforations l5. If a block of this type is divided into veneers by parallel saw cuts in the manner described,

a plurality of glue surfaced initial pared-01f veneer sheets having fibres belonging to the same period of growth of a trunk, heating and initially pressing a limited rim portion of the stack, increasing and gradually extending the pressure 1 until coveringthe entire stack area, to deform the individual sheets out of their original planar surface, allowing the stack to cool and set into a block, driving wooden pegs through said block transversely to said-sheets, and cutting said'block into final veneers.

2.--In a method ofproducingartificially veined wooden veneers by transversely cutting a con" solidated block of initial sheets of pared-oi veneers each consisting of fibres belonging to substantially the same period of growth of va trunk, the steps of heating a. stack -of initial glue-sur faced pared-ofiveneer sheets, initially compressing a limited marginal portion of the stack area to deform the individual sheets into a corrugated shape out of their initial planar shape, progressively increasing and extending the deforming pressure until covering the entire sta'ck area, allowing the stack to cool and set into a block, and transversely cutting said block into final veneer sheets.

pared-off veneer belonging to the same period of growth of a trunk, while simultaneously the entire stack area, thereby, to defOrm the individual sheets-out of their original planar surface; allowing the stack to cool and set into a block, and cutting said block into final veneers.

EMIL FREIHERR VON ENDE. HEINRICH GEFFCKEN.

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