DE4222866C1 - Method of producing solid wooden laminates - involves gluing and pressing thin sheets of timber and then drying them and either sorting sizes or sawing and sanding to size - Google Patents

Abstract

The method produces solid wooden laminate, particularly a composite plate, from dried wood. Squared timber is sawn up into thin planks, which are then glued and pressed together. The planks are then dried to a final moisture content of between 4 and 12% by weight, typically in a stack in a drying chamber, which can be of the flow-through type. They can be sawn to the same thickness, and sanded down mechanically after drying to even out any shrinkage. Alternatively they can be sorted after drying into different thicknesses. ADVANTAGE - Gives same quality and dimensional stability as sawn planks.

Description

The present invention relates to a method according to the preamble of claim 1 Manufacture of a solid wood laminate product especially a solid wood composite panel.

Solid wood laminate products are made from thin Boards made that glued under pressure will. Such laminate products are known, they have the advantage over non-glued solid wood that due to the gluing, especially in Solid wood panels are also made crosswise that Strength properties of the products partial elimination of the isotropy of the wood and by reducing the influence of Vulnerabilities such as knots and the like are improved can be.

Both for the later use of Solid wood laminate products as well as for Manufacturing process of gluing under pressure and Warmth it is necessary that the thin boards, from which the named products are made, a certain moisture content exceed. If the humidity is too high, for example when hot pressing the boards explosive surface cracks due to evaporating Moisture. The moisture content of the thin Boards should therefore in any case less than 15% by weight is usually a humidity in the range of 4-12 wt .-% required, with products for the Indoor use in general in the area of boards higher dryness, d. H. with a moisture between 4 and 8 wt .-%, are used.  

If in this context of thin boards the Is mentioned, so are boards in general Thickness range from 4 to about 16 mm is meant. To Conventional processes use these thin boards produced by sawing squared timbers. It is important to ensure that the boards have the same thickness as possible so that they corresponding to layers of uniform thickness can be put together. With too big Differences in thickness can be mechanical Postprocessing may be required if High quality laminate products are produced should.

To meet the requirements of a minimum dry matter content sufficient and boards of the same thickness as possible the squared timbers from which the thin boards can be obtained by sawing their division to the desired final moisture dried.

Processes have recently become known at to whom the thin boards are not sawed, but by simply cutting square timber be won. This method of production has the great advantage that the squared timbers practically without Almost 100% material loss divided into boards can be. In contrast, when sawing cuts the thinner the sawdust, the more waste produced boards are. The proportion of waste can be up to 40% go, which is a relatively uneconomical Use of the material wood means.

The cutting production of thin boards sets in general, however, square timber ahead, which one do not fall below a certain moisture content supposed to be a certain when cutting  Preserve surface quality of the boards. At the best freshly cut wood is cut. This means that the squared timbers to be cut beforehand must not be dried. When cutting Can produce thin boards for laminate products the drying step is therefore compulsory only to the cut boards. The Saving raw materials and energy when cutting is producing thin boards though extremely desirable to process the cut boards to laminate products but also certain problems. So they will cut boards because of the finite thickness of the used knife a certain deformation subject if they are on the side of the cutting Knife bevels must be derived. Here different structured surfaces are created the boards. Wood is also shrinking as is known when drying. The extent of However, shrinking is in the three wood directions, namely in the longitudinal direction, parallel in the transverse direction to the annual rings and perpendicular to the annual rings different, which is why the Dry shrinkage on boards of the same thickness were cut, depending on where they came from Boards in the trunk can be different.

The one with cutting thin boards related processing problems However, laminate products were largely solved be so that even using the Cutting process to produce laminate products whose surface quality is that of Laminated products from sawn boards corresponds, if not better.  

Observations on solid wood composite panels However, cut boards have meanwhile reveal that these plates are generally better Have dimensional stability as a corresponding Boards made of sawn boards.

The invention is based on the object Show method with which also sawn out Boards of solid wood laminate products of the same quality and dimensional stability as in processing can be obtained from cut boards.

This object is achieved by the in Claim 1 specified sequence of Process steps solved.

It is not believed that the better Dimensional behavior of the laminate panels cut boards in any way whose cut surface or with the at Cutting occurring deformations related. Rather, the one that has not yet been confirmed appears to be secure Realize that drying of the thin boards after cutting the squared timber in the Contrary to drying the square timbers before Cut up like sawing the thin ones Boards have been common until now observed quality improvements.

The invention therefore provides, in contrast to previous methods of generating Solid wood laminate products from sawn boards here, too, only close the boards after sawing dry.

It is not generally necessary that all drying takes place after sawing.  

According to the invention, however, is at least one Final drying step on the already produced thin ones Boards. In a preferred embodiment of the method according to the invention, however entire drying required only on the already sawn thin boards. This has the additional advantage that energy already when sawing can be saved because even when sawing fresh wood can be processed more easily than already dried. Furthermore, the one to be dried Amount of wood after sawing and thus also the drying energy to be used less because of Sawdust waste can no longer be dried needs. Another advantage is a shorter one Drying time because thin slats dry faster as thick woods.

The execution of the drying step on the sawn Boards instead of on the undivided squared timbers the further advantage that squared timbers Let use those that are low from logs Diameter have been generated. It is known, that squared timbers tend to crack during drying. However, this cracking can be greatly reduced are used when so-called "cross sticks" are used. Crosswoods are cut from the log, that two mutually perpendicular cuts through the Tribe center in the longitudinal axis of the trunk, the maximum that can be generated from a trunk cross-section Kantholz is quartered. This by quarters emerged crosswoods, which are the pith of the Tribe not in the middle but roughly along have one of their corners less prone to Cracking because they are each quarter circles of the Annual rings included. So you wanted after that conventional processes relatively crack-free thin boards by sawing cutting  Dried squared timber had to be preferred such crosswoods are used, but only created from appropriately large trunk cross sections could become. In the method according to the invention, where the cut boards first dried the full squared timber cross sections processed from a thin trunk can be generated.

On the other hand, the method according to the invention has of course the disadvantage of possibly different shrinkage of boards that sawn from the damp wood with the same thickness were. However, this disadvantage can be overcome eliminate if necessary by measures such as they meanwhile for the generation of Laminate products made from cut boards were developed. For example, it is possible the dried boards of a comparative Surface processing by grinding, planing or to submit to the like. It is also possible that Boards with automated methods according to the Sort by thickness or when drying Squares with an even layer from the trunk to the Use, the expected loss of thickness ever after the position of a board in the trunk cross-section to be considered when sawing.

Drying the thin boards can be done in Continuous dryers, but also in drying chambers done in which the boards dried in the stack be, the board stack preferably so are designed so that the dry air as possible has access to the boards from all sides. This can by parallel stacking and inserting Spacer bars between the layers when stacking and / or by crosswise stacking.  

Especially when using Continuous dryers can also be useful be the boards while drying on the Load conveyor belt so that a possible Curl of the boards can be reduced. Also a scheduled drying of the thin boards on the Air is said to use the method described be included.

The control of the drying process in the Dryers can be done in a known manner.

Claims (7)

1. A method for producing a solid wood laminate product, in particular a solid wood composite panel made of dried wood, in which squared timber is cut into thin boards by sawing and at least two layers of such thin boards are glued and pressed to form these laminate products, characterized in that the thin boards be dried by sawing the squared timber after its production. 2. The method according to claim 1, characterized characterized that undried squared timber too is cut up on these thin boards. 3. The method according to claim 1 or 2, characterized characterized in that the thin boards on a Final moisture content of 4-12% by weight can be dried. 4. The method according to at least one of the claims 1-3, characterized in that the thin Boards in a stack in a drying chamber be dried. 5. The method according to at least one of the claims 1-3, characterized in that the thin Boards dried in a continuous dryer will. 6. The method according to at least one of the claims 1-5, characterized in that thin boards sawn the same thickness and the thin boards after drying to compensate different dry shrinkage one comparative mechanical Be subjected to surface abrasion.   7. The method according to at least one of the claims 1-5, characterized in that thin boards sawn the same thickness and the thin boards after drying in board classes of the same thickness be sorted.