DE1728175A1 - Dimensionally stable hardwood panel - Google Patents

Description

PaHntanwäH »

ing A Grünecker

^1J drying. Ή. 'Kinkeldey 1728175

Dr.-lay. W. Stockmair S Munch * 22. MaxlmHioMtr. 43

P 2105

Weyerhaeuser Company
Tacoma, Washington 98401

Dimensionally stable hardwood panel

The invention relates to a dimensionally made Plywood board with an Ee.r * n made of resistant material, a front and a back sheet, as well as a method for their production.

Ee is known that Hol75 is changing its dimensions under Moisture conditions across the grain are considerable changed, on the other hand, parallel to a grain direction, has a «good dimensional accuracy. With conventional plywood, at where the front and back layers are made of the same type of wood and are equally strong and the core is wood veneer, there is the resulting layered material during changes dee Moisture content quite dimensionally stable. Conventional 6.35 ea- (1/4 inch) earth plywood consists of three layers of wood veneer. Typically the two overlap layers are 1 - 0.7 mm (1/24 ~ 1/36 inch.) etaric and with the inner layer in such a way that you can see it

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directions run parallel to each other. The inner layer is about 4.2 * mm (1/6 ⁿ ) thick and the direction of the fibers is perpendicular to that of the outer layer.

Numerous patents have been granted to improve the dimensional accuracy of various plywood boards. For example, according to US Patent 3r. 2 286 068 a Dimensionally stable soft plywood board with front and back layers of essentially the same? Thickness with parallel grains due to a random distribution Grooving of the front sheet of the plate achieved in all sightings. In U.S. Patent No. 2,563,98? -will described a soft plywood board that was made true to size is done by initially using an unbalanced plate is launched. i.e. a plate in which the two deodorant suits are of different strength, and that the unbalanced plate by grooving the stronger location, balancing it back to an actual strength · the the thickness of the opposite top layer is the same. U.S. Patent No. 2,782,468 describes a method of making a balanced grooved plywood sheet, while grooving is essentially the same Holzmeuge is removed in front of the front and the rear layer.

If a resilient core material such as pressed or Chipboard, which is relatively strong compared to the face veneer, as an inner layer in the manufacture of a

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Harteperrliolzplatte is used to prevent di · strength, stiffness and stability of the inner layer Ια "ββentlichen all llaßveränderungan 6 wood veneers. If, on the other hand, a resistant core material is used as the inner layer, which is thin in relation to the face veneer, then its strength and rigidity are insufficient to prevent the face veneer from changing in size. This lack of effective obstruction of the core material enables the panels to expand or contract excessively with changes in moisture content across the fiber rim. Plates produced in this way are difficult to use for commercial purposes and are not widely used.

It was found that by attaching a veneer of normal thickness on a surface of a tough core material at right angles to one the other surface of the core material arranged others Normal thickness veneer limits dimensional changes became. When reducing the wood mass of both Deeklagen through Grinding, using veneers, their thickness is below the normal strength, or in another way, can a panel with good dimensional stability and without excessive throwing can be obtained.

The invention relates to «in · dimensionally · plywood board with a core eus resistant ·» EattrlaX,

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for example, pressed or hardboard, and a front and a backing and eats according to the invention, characterized in that the fiber run of the front layer is perpendicular runs towards the grain of the backing. You top layers are preferably of a low thickness and are obtained by grinding, by using veneers under Bformal thickness or in some other way.

In contrast to the conventional 6.35 mm (1/4 inch) plywood, in which the Faeerrichtucgen both outer layers run parallel to each other, the panel according to the invention Cover layers, the fiber directions of which are perpendicular to each other. By arranging the top layers at right angles fiber direction running to each other and by using face veneers with normal thickness, a board with a good dimensional stability with little or no tendency to warp or twist.

In the following an embodiment of the invention is described in connection with the drawing. Show it

Fig. 1 is a front view of a plate part with

broken away successive layers, and Fig. 2 the EndaneicAt of a plate part and the right-angled course of the fiber stripes of the two outer layers to each other.

The plate 10 consists of successive layers 12, 14 and 16. The fiber direction of the front layer 12 runs

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Rechfcv / inklig to the pE-.ari.iLuhtur.g '' nr backing 16. The Kerniaaberial 14 kuun au «bolisbigsia resistant
Material consist of _t bel ^ xelsweriae P plate; Chipboard, hardboard or ε>: ± 0ύζβη rcrdicfatsten fiber structures, tiie by hot pressing from Fa? .Ex-f: '. L: - y.-i made with or without resin vrerderu In all gone inofl isb the core material a curist resin-glued material made of wood »Through this
Cutting is divided into parts of preliminary forms, which are glued by means of an adhesive and connected by means of a (Procken method ;; u ain-ar Pl? T üo . Dem
Any natural fire retardant materials may be added to the core material. Further additives can be added to the core material on request. The carnation material is preferably about 1 / 6th of an inch thick. Core materials of much greater strength are not considered here. Tons of thinner core materials can be used if a densified product can be made with properties equivalent to those of 4.25 πω (V6 inch) thickness.

The front veneer 12 can be made of hard or soft wood, for example Walnut, birch, oak, fir or elm wood exist. Veneers of normal thickness are used, the thickness of which is 0.7 - 1 mm (1/56 - 1/26 incb).

The back veneer 16 can consist of any wood or other material with oriented fibers, for example birch, elk, elm or lauan wood.

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The panel according to the invention is made by spreading a conventional adhesive, such as urea-formaldehyde resin, on the core material 14 by attaching a front fixing 12 to the core material 14 with the fiber direction parallel to the L & agsabmesaung, a back veneer with the fiber direction in the right Angle to the direction of fit of the front face 12 is attached to the core material 14, the panel is hot-pressed and a sufficient amount of wood is removed from the front and back veneers to correct the dimensional accuracy and tilt of the panel. This amount of wood can be removed by sanding or kept low by using thin veneers or in another orphan. After finishing the front veneer and gluing the board, the front of the board can be provided with old V-shaped tiles (V-grooved) in order to apply decorative effects to the board according to Wimsch.

The amount of wood to be removed from the front and back veneers must be sufficient to correct the dimensional accuracy of the panel. It has been found, for example, that in the manufacture of 6.3-5 m (1/4 inch) plywood using 4.25 Ω & (1/6 inch) core materials and face veneers with an aural thickness of 0.7 - 1 ma (1/36 * 1/26 inch) the distance of 0.38 mm - 0.64 ma (0.015 - 0.025 material of the front and back veneer auentiobt, t

Flat · the · desired leasability and throw-free · sense «.

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lend shafts.

In an attempt to measure the dimensional accuracy of 1.22 m 2.44 m χ χ 6.35 mm (48 to 96 - 1/4 inch) uses large plywood boards (1/36 inch) by the attachment of a 0.7 Hardwood front veneer was made on a press plate ceramic material by means of a normal urea glue and by attaching a back veneer to the other surface of the core material in such a way that its fiber direction was perpendicular to the 2.44 m dimension. The plate was heated at 250 ° F (121 ° 0) for a minute. hot pressed. Wake up to six to seven hours, the panels were cut to the exact size and the backing veneers sanded to a decrease in thickness of approximately 0.5-0.635 mm (0.020-0.025 inches). The front veneer was then sanded and about 0.125-0.25 mm (0.005-0.010 inch) thick. The panels were then V-grooved, the surfaces fine sanded (with a further 0.25 - Ο »33 mm (0.010 - 0.015 inch) removed) and colored using conventional methods *

The plate made after this process in full width and part of a ?. ^v Bsfesulgungawand (stud wall) were dried to a moisture content of approx. 2-3%. Several panels were nailed to the wall and butted together as in a real installation. The moisture

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content was then increased to about 1J - 15 % yea " ¹ ^ d the plates were observed to bulge away from the land due to the increased moisture content. This process simulates the changes occurring in plotters when they are installed under dry conditions in winter and then exposed to humid conditions in summer.

Ee was found AEC: ß calibration a plywood board from a thin Preßplattenkern and para l lel s top layers under the above conditions by 9.5 - 15 »β mm (3/8 - 5/8 inch) wegbog from the wall. In addition, if the moisture content was reduced to 2-3%, the panels did not become completely flat again, so that permanent damage had occurred.

It was found that a sheet of plywood _t * which have been manufactured according to the invention "? Ar, ie with a PreßplattenkexJB. Röcht and? / Inirlig each other extending fiber direction of the front and rear position, is only about 1.58 mm (1/16 inch ) from the sand svegbog.

In the case of a reversal of the previous ^ cn-umter. When attempted when high moisture panels were attached to the wall and then dried, gaps appeared between the panels. In the case of plates made from Einsi press plate core and parallel

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Fore and ilinbsifurnlereii resulted in gaps of about 6.35 ß ™ (IA inch), which is too large for commercial purposes. Plates according to the Erf Inciting other hand, revealed a gap 'of only about 1.58 now (1/16 incJi), which is considered to be acceptable.

- claims

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Claims (1)

Claims Λ J Dimensionally made plywood board with a core of resistant material, a front and a back layer, characterized in that the grain direction of the front layer runs perpendicular to the grain direction of the back layer. 2. Plate according to claim 1, characterized in that the front and back layers prior to grinding 0.705 - 1 nrn (1/36 - 1/26 inch) thick. 3. Plate according to claim 1, characterized in that the core material is a compressed fiber material is· 4th plate after. Claim 3, characterized in that the core material is approximately 4.25 mm (1/6 inch) is strong. 5. Plate according to claim 4, characterized in that the thickness of the front and back layers ranges from 0.25-0.51mm (0.010-0.020 inch). 6. Plate according to at least one of claims 1 - 5t, characterized in that the goal position one made from oak, elm, birch and walnut Group is chosen hardwood. 209811/0603 BATH 7 · Plate according to at least one of claims 1-6, characterized in that the backing is a hardwood material. 8. Method of making a dimensionally accurate Hardwood plywood board, characterized by a) spreading an adhesive on each surface of the resistant core material, Φ b) the laying on of a methanol front veneer of 0.7 - 1 sim (1/36 - 1/26 inch) thickness on the surface of the core material, c) the laying on of a Ha; thol back veneer of essentially the same thickness is applied to the front veneer the other surface of the core material, with the grain direction of the Kinterfurnlere perpendicular to the grain direction of the front veneer runs, d) pressing the plate under heat and pressure for fastening tion of the layers, and e) removing an equal amount of wood from the front and deposits, which eut Yerininderaat, an excessive Throwing the plate is enough. 209811/0603 Blank page