DE718096C - Process for the finishing of wood veneers by cold rolling - Google Patents

Description

Process for finishing wood veneers by cold rolling All through Wood veneers made by peeling and knives have defects because: the natural The structure of the wood is partially destroyed by the action of the knife. It can z. B. numerous small cracks occur, which are caused by the pressure of the knife on the softened wood or, in the case of peeled veneers, also due to the smaller diameter of the Insides arise when laying flat. As a result of this damage, all such, Wood veneer more or less brittle when dry and also warping more subdued than raw wood. It is known that in the manufacture of plywood the disadvantage of the warping of the raw veneer makes itself very noticeable, so that it So far it was not possible to produce plywood that was resistant to warping Book are.

In the case of polished objects, there are numerous continuous ones Cracks from the working of the wood are uncomfortably felt because they are the polishing layer destroy again and again.

Finally, the wavy ones that show the most beautiful grain Root wood makes processing the very uneven raw veneer difficult, the numerous porous end grain areas are extremely difficult to seal and the execution polishing on it requires an unusually long and arduous work. The polishing layers keep adding shine because the polish in the The porous base layer sinks in and jumps over the pores and cracks of the wood rips.

In the case of large-pore woods, e.g. B. Oak wood, does the filling. the pores considerable difficulties even with massive wood. This disadvantage. is with such Veneering as a result of the numerous beire. Knife or peeling unavoidable cracks in, increased measure available.

Next, the brittleness of the dry eats Veneers and their poor flexural strength is a deficiency. The drier the veneers are, around the more the brittleness increases. The veneers tear and break when you touch them and processing extremely easily due to their utter lack of elasticity. This low breaking and tensile strength is also found when processing plywood very disadvantageous.

In the case of the valuable Maserfurneren there is also the fact that such as a result of their wavy structure always particularly uneven, warped and therefore easily brittle and are difficult to process.

All these disadvantages can be completely eliminated in that the dry veneers with full retention of their natural water content by repeated cold rolling under increasing, very evenly over the surface continuous pressure and thereby gradually smooths and compacts the structure in a similar way to processing metal, with the veneers after each Passage by narrowing the rollers a little more pressed and a little something be rolled thinner. This results in a complete redistribution of the wood fibers instead of. This roll pressing process makes the veneers uniform across their entire width stretched and thereby the wood fiber bundles of the hard annual rings into the soft fibers pressed in and stored diagonally next to and on top of each other, which increases the toughness of the whole structure is greatly improved.

It is well known to use wet veneers in the production of raw veneers to roll and thereby to free them from an excess of water. Alone there the swollen one Wood fiber cannot be compressed even under the strongest pressure, so such remains Veneers unchanged in strength after their completion and have after drying exactly the same drawbacks as noted above.

Rolling with heated rollers or hot pressing also makes it straight achieves the opposite of what the invention aims; because due to increased temperature is the natural water content of the wood, which is normal on average about i2% is reduced, thereby increasing the brittleness of the wood fiber.

Likewise, with laterally displaceable and rotating rollers, such as she z. B. for smoothing. using thin boards for cigar boxes, the aim pursued by the invention can never be achieved because it is the inner The wood structure remains completely unchanged and air-filled, the smoothing rather superficial takes place by the lateral movement of the rollers, which exert a kind of grinding effect.

Finally, it is known to press fluted veneers again with rollers. However, this achieves that instead of increasing the tightness and toughness first an elongation and then a compression, i.e. a reduction in the area of the veneers entry. However, this appears to be disadvantageous for the structure.

In contrast to this, the new process turns the wood in its The structure is changed in such a way that at the end an almost homogeneous, pore-free, has formed stretched mass in the surface.

To prevent resinous woods from sticking, the Before rolling, veneer by lightly rubbing or painting * (wafer-finer coating) with anhydrous masses (also in powder form) or solutions the material used for rubbing or painting also some grease or suitable binders, e.g. B. cellulose, adhesive or the like .. may contain. Avoid water to prevent the wood fibers from swelling. At all, The content of sap and resin components is particularly useful in the case of resinous woods to make the air-free pressed wood veneers particularly durable, because the pores stuck together by the juice and resin components even when swelling change only insignificantly and never return to the previous form can.

According to the current procedure, the veneers are carefully rolled once and then under increased pressure as a result of the rollers being tightened, similar to Production of metal sheets, rolled several times until they have the desired thickness, Have obtained smoothness, toughness and suppleness. By this taking place Compressing the wood fiber and pressing the hard into the soft annual rings the wood loses all pores. The veneers are then perhaps almost free of air and consequently the swelling and shrinking due to humidity only to a minor extent Subject to dimensions.

The processing of such veneers for furniture is greatly facilitated, because they are easier to polish and smooth. The gloss of the polish remains Preserved for a particularly long time because the polishing layer is no longer in cavities as before can sink in.

Plywood made with such veneers is several times that more resistant and; more elastic than those made from ordinary raw veneers and are no longer subject to forgiveness. This progress is in particular also for the production of waterproof wooden bodies and aircraft parts and the like of importance.

Claims (1)

PATENT CLAIMS: i. Process for finishing wood veneers Cold rolling, characterized by the use of smooth, air-dry veneers, which are compressed several times under increased pressure in their structure. a. procedure according to claim i, characterized in that the wood veneers by light. Run over be prepared with anhydrous masses or solutions.