EP2842707B1 - Method for the manufacture of a laminated wood beam - Google Patents

Description

The invention relates to a method for producing a construction lumber consisting of several lumbers.

In recent years, the timber industry has received an increasing demand. In particular, in wood constructions, such as in house building, wood is increasingly being used because wood is associated with many positive qualities, such as "natural", "comfortable", "beautiful" and "individual". The demands on wooden constructions, in particular beams of layered lumber, for such wooden constructions, are increasing steadily.

For example, the structural timber is known for modern timber construction. From top quality coniferous wood, raw beams or lumber are produced. These are dried and sorted according to the strength. Defects contained in these lumbers, for example strength-reducing growth deviations, branches or the like, are subsequently cut off. The individual sections of the lumber are connected by finger jointing and cut to a strand formation to the desired final length. The side surfaces of the raw strands are then equalized. Thus, the structural timber consists of a single-layered structure, in which the individual lumbers are processed as solid wood and are connected by the Auskappung of defects by finger-jointing.

Furthermore, in modern timber construction, the production of a so-called glued laminated timber is known. This board or lamellar lumber from a raw material, ie tree trunks, produced. The individual lumbers are visually / mechanically sorted and defects are marked. Subsequently, flaws are removed and the finger joints are created to produce the lumbers that are used by the defects are freed to reunite with each other to a strand. Subsequently, a capping of the strand is carried out to a predetermined length or a target length. After a leveling of a Beleimfläche, which corresponds to the broad side of the glulam, gluing takes place. Subsequently, several strands produced by the finger joint connection are pressed together from the lumber, creating a rough laminated beam. Finally, a finished planing of the raw glue binder, so that a four-sided processed glued laminated timber is made.

The DE 24 04 490 B1 relates to such above-described glulam beams, which are connected by the finger joint to a long carrier. Analog goes out of the DE 10 2007 061 318 B1 as well as the EP 0 607 480 A1 out.

Furthermore, the production of a laminated plywood for the production of so-called duobalk and trio-barley is known (duobalk and trio bar are registered trademarks). As a basis for the production of such timbers serve planks or squared timbers with a thickness of up to 80 mm with a width of up to 280 mm and a thickness of up to 120 mm with a width of up to 100. The production of such multi-layer duo or trio balkes takes place in analogy to glued laminated timber with board or lamellar cut lumber.

From the EP 1 510 309 A1 a method for producing a construction plywood of several plywoods is known, in which produced from a raw lumber with respect to their longitudinal side are glued together. Optionally, in a preliminary step, one longitudinal side of the lumber can be leveled before the adhesive is applied and glued to the adjacent lumber. In this optional step also a defect in the sawn timber can be processed.

Subsequently, the glued together lumber can be cut and connected to each other at the front by a finger joint.

From the US 2001/0004482 A1 a method for producing a construction plywood of several lumber is known in which lumber produced from a raw material are sorted visually or by machine Then the lumber are sorted out with defects. Subsequently, at least one side surface of the lumber is leveled and applied an adhesive. Several adhesive lumbers having a finger joint on the gluing surface are joined together. Subsequently, these juxtaposed and glued together lumbers are in turn cut to a further cutting blank, which in turn is then connected to each other at the front sides by finger joints.

The previous beam constructions require a commodity of large dimensions, that is, tree trunks are used that require growth between 60 and 80 years or more. Such raw material is becoming increasingly difficult. On the one hand, this is due to the fact that there is no longer any need for a metering system for valuing the hardwood and, secondly, an increased use of chip technology, so that in the upper starch classes of raw materials, for example over more than sixty years, in particular more than eighty years, no price increase is possible anymore. In addition, an early timber harvest is initiated to avoid economic disadvantages that arise, for example, storm damage. In addition, there is also a reduction in production areas due to nature conservation requirements. There will be more and more new national parks in which a cultivation of land is prohibited.

The invention has for its object to provide a method for producing a structural plywood, and to propose a plywood construction to allow a more cost-effective production.

This object is achieved according to the invention by a method for producing a multi-cut timber A construction plywood is provided in which the lumber produced from a raw material is visually or mechanically sorted and the flaw-containing sawn timber not directly adjacent to a front portion of the lumber is sorted out, wherein the flawless lumber is leveled on at least one side surface of the lumber the at least one side surface of the lumber is applied to form a Beleimfläche an adhesive, several lumbers are stacked with Beleimflächen and glued by compression to a Bauktionsschichtholzrohling and subsequently each a frontal end of two mutually associated Bauktionsschichtholzrohlingen are connected by a universal wedge joint joint. By this method, a construction plywood is made of non-finger-jointed lumber. This method enables a raw material, ie tree trunks with a growth of up to 40 or up to 60 years, to be used for the production of the sawn timber for further processing into a construction plywood. The use of small wood aged between twenty and a maximum of fifty years is made possible by the process. With such a younger raw material is a better availability than for tree trunks with a growth up to 60 years or older given and thus a cheaper purchase of the raw material possible. In addition, in the production of less energy for the drying is given, since in the inventive method lumber can be used with a smaller cross section than in the production of solid construction timber according to the prior art. The wood quality is also higher, due to smaller branch sizes. In recent roundwood, there are slight stresses in the core area in comparison to older roundwood, which can lead to cracks during further processing, in particular timber drying. These cracks are quality-reduced and produce rejects and just these do not occur in the construction of visible light.

Under a lumber, which is made of a raw material, a machined on Schnittmaß round timber is understood as squared timber, without this includes a finger joint. Edged lumbers are free of finger jointing.

A preferred embodiment of the method provides that after gluing the lumber in layers and via finger jointing, the other side surfaces of the individual construction lumbers each side surfaces of the structural timber blank are equalized. This allows the construction wood blank to be manufactured to the final edge dimension.

Preferably, the structural wood blank is then capped to a target length. As a result, flat end faces can be produced on the construction timber blank for the completion of the construction plywood. The length capping can also take place before the leveling of the side surfaces or is dependent on the production.

It is preferably provided that the sawn timber is cut from a raw material which is classified in a weak round wood class. It is envisaged that the round wood class 1a to 2b will be selected, that is to say that dimensions of the raw product have a thickness of about 60 to 80 mm and a width of 100 to 150 mm with a length of between three and five and a half meters. This assumes that the raw material is cut to a certain extent to compensate for loss of size due to shrinkage and leveling.

The sawn timber is preferably produced as raw material from tree trunks with a diameter at the end of the pile of 140 to 255 mm. The availability of such tree trunks is much greater and thus the raw material is less expensive than older tree trunks.

A further advantageous embodiment of the method provides that a sorting according to DIN 4074 is performed, this may be visually as S10 sorting or mechanically, so that sorted woods meet the requirements of the strength class C24. This means that a visual / mechanical sorting for defects in the lumber takes place and in the detection of defects in the sawn wood, a complete sorting out of the sawn wood takes place. Consequently, only such lumbers are used for the production of a structural plywood, in which there are no or only minor flaws that are within the allowable tolerance.

The process according to the invention provides that cut lumbers are processed further, which have defects only in the front region of the sawn timber. Such imperfections are not critical because they are separated out in the production of the finger joint profile for a subsequent finger joint.

In this method, it is preferably provided that both a broad side and a narrow side of the lumber can be selected as Beleimfläche, Thus, construction timber can be created, comprising two or more glued together lumber, which are glued to the broad side or the narrow side. As a result, various dimensions and visual appearances can be achieved.

Preferably, the lumbers have rectangular blanks, the thickness of which is equal to or less than 80 mm, in particular in a range of 60 to 80 mm, formed in the finished product state. On the one hand this allows a shorter drying time and thus an energy saving. In addition, an increased dimensional stability can be achieved due to the lower shrinkage than squared timbers. On the other hand, a sufficient rigidity can be achieved in the construction plywood, which is made of a weak round wood.

Preferably, the rough cutting length of the sawn timber is between 2.5 and 5.5 m, wherein preferably equal to the same long cutting lengths of the lumber used for gluing to a construction plywood. As a result, after clipping, only a clipping of an end face for a uniform reference surface or a continuous end face is required, resulting in only a small amount of rejects.

The object underlying the invention is further achieved by a construction plywood, in which a plurality of stacked, glued together lumber, which are free of a finger joint, one or more joints due to their partly different lengths, each joint by a over the entire Cross section of the construction wood blank extending universal spline connection is formed. In the case of several glued and superimposed lumbers, a common joint is formed and connected to the abutment point of the further structural timber blank by a finger jointing.

• Figuren 1 bis 7 mehrere schematische Darstellungen von einzelnen Verfahrensschritten zur Herstellung eines erfindungsgemäßen Konstruktionsschichtholzes aus mehreren Schnitthölzern.

The invention and further advantageous embodiments and developments thereof are described in more detail below with reference to the examples shown in the drawings and explained. The features to be taken from the description and the drawings can be applied individually according to the invention individually or in combination in any combination. Show it:

• FIGS. 1 to 7 several schematic representations of individual process steps for the production of a construction plywood according to the invention of several timbers.

In the FIGS. 1 to 7 are individual process steps for the production of a plurality of lumber 12 existing construction plywood 11 shown. Such a construction plywood 11 may also be referred to as beam plywood.

In FIG. 1 In a first method step, a visual or mechanical sorting and testing of the sawn timber 12 provided as raw material is carried out. The sawn timber 12 comes from a weak round wood, that is, from tree trunks whose pigtail end, for example, equal to or less than 255 mm. From this square or rectangular lumbers 12 are sawed, which are provided for the production of the construction plywood 11. In particular, the lumbers 12 are manufactured with a thickness of less than 80 mm and a width of less than 150 mm. It Both coniferous and hardwoods can be used, but preferably conifers are used, which have a higher load capacity.

For visual / machine sorting according to FIG. 1 a so-called S10 sorting according to DIN 4074 is carried out or it is mechanically determined whether the lumbers meet the requirements of strength class C24, whereby any lumbers 12 are sorted out which defects 24 (FIG. FIG. 4b ), except in an immediate forehead area 22 of the lumbers 12. The defects may be, for example, cracks, knots, insects, clustering, rot, discoloration, reaction wood, tree ring widths, or the like.

In a next processing station according to FIG. 2a or FIG. 2b Side surfaces 14 of the timber 12 are equalized by a tool 15, such as by a planer. Preferably, the two opposite side surfaces 14 of the lumber 12 are equalized, so that two plane-parallel side surfaces are formed. At the in FIG. 2a illustrated embodiment, the broadsides are leveled to form at least one Beleimfläche 17. In FIG. 2b the narrow sides 20 are equalized.

In a subsequent processing step according to FIG. 3a the narrow side 20 is provided with an adhesive 16 from a coating direction 19, so that a Beleimfläche 17 is formed. In FIG. 3b Analogously, the processing of the broad side of the lumber 12 is shown, for example, four lumbers 12 are glued together. In a press, not shown, the individual lumbers 12 are pressed together with their Beleimflächen 17 against each other and fixed so that they are to a construction timber blank 18 according to the Figures 3c or 3d are connected. In this case, according to the embodiment in FIG 3d figure the wide side surfaces 14 are glued together. It is envisaged that, for example, two or three of the lumbers 12 aligned with their annual rings the same and an end-side timber 12 is aligned rotated by 180 °.

Alternatively, it can also be provided that the lumber 12, 12 is connected to the formation of the structural timber blank 18 with its narrow side 20 ( Figure 3c ), wherein, as shown in the embodiment, the annual rings of the two connected lumbers 12 are rotated by 180 ° to each other.

The in the FIGS. 3a and 3b illustrated examples of the construction wood blanks 18 are in a further processing step according to FIGS. 4a and 4b capped, that is, a stimulus region 22 is produced with a flat end face 23 ( FIG. 4b ).

If, for example, a defect 24 is contained in the end region 22, as is illustrated by way of example in FIG FIG. 4a is shown, this is removed by attaching.

In a subsequent step are in a processing station according to FIG. 5a in the end faces 23 of two opposing construction wood blanks 18 finger joints 26 introduced, which extend along the entire end face 23. This is in detail in FIG. 5c shown.

Subsequently, the finger joints 26 are again provided with adhesive and pressed into their connection into each other and glued. This results in a universal wedge tine 28, which extends over all involved in the construction of the structural timber blank 18 lumber 12. In a last processing station, such as in the FIGS. 6 and 7 is shown, the other side surfaces 14 of the structural wood blank 18 are again equalized by a tool 15, in particular a planer. The opposite side surface 14 is also equalized and removed to the target size of the structural timber 11. In addition, the other side surfaces 14 can be equalized and made to measure again. Subsequently, the construction timber blank 18 is cut to the desired length, so that the construction plywood 11 or the beam plywood, which has been worked on all side surfaces and end faces, is completed. A lengthening is also possible before the leveling of the side surfaces 14. Analogous processing is carried out in a construction plywood blank 18 according to FIG FIG. 5c ,

The construction plywood 11 or beam plywood produced by this process is in FIG. 7 and may correspond to the structural properties of the product in terms of product characteristics, however, the raw material is better and more cost-effectively available. Due to the lower wood moisture compared to solid construction timber, a higher dimensional stability is achieved. The construction plywood 11 may also be made of the structural plywood blank 18 according to Figure 3c respectively FIG. 6 exist in which the narrow sides 20 of the laminated wood 12 are glued.

Claims (9)

1. A method for manufacturing a laminated construction timber element (11) consisting of a plurality of pieces of sawn timber (12), said method comprising the following steps:

   - the pieces of sawn timber (12) produced from raw material are visually sorted or machine-sorted,

   - when a void or imperfection (24) is detected in any of the pieces of sawn timber (12) which is not immediately adjacent to an end face area (22) of the sawn timber piece (12), said piece of sawn timber (12) containing the void or imperfection (24) is sorted out and replaced, for further processing, by a piece of sawn timber (12) which does not have any such void or imperfection,

   - at least one lateral face (14) of the piece of sawn timber (12) is levelled,

   - an adhesive (16) is applied to the lateral surface (14) of the piece of sawn timber (12) in order to form a gluing surface (17),

   - a plurality of pieces of sawn timber (12) including said gluing surfaces (17) are stacked and glued together under pressure so as to form a construction timber blank (18), and

   - subsequently, an end face (23) of each one of two construction timber blanks (18) associated with each other is provided with finger joints (26) and said blanks are assembled together by means of a universal finger joint assembly (28).
2. The method as claimed in claim 1, characterised in that the other lateral surfaces (14) of the construction timber blank (18) are levelled.
3. The method as claimed in claim 1, characterised in that the construction timber blank (18) is cut to a target length.
4. The method as claimed in claim 1, characterised in that the pieces of sawn timber (12) are cut from raw material of a low-strength round timber class.
5. The method as claimed in claim 1, characterised in that the pieces of sawn timber (12) are fabricated as blanks obtained from tree trunks with a diameter ranging between 140 mm and 255 mm at their top end.
6. The method as claimed in claim 1, characterised in that such S10/MS10 grading is carried out in accordance with the DIN 4074 standard.
7. The method as claimed in claim 1, characterised in that one lateral surface (14), which represents a broad side, or a narrow side (20) of the piece of sawn timber (12) is selected as a gluing surface (17).
8. The method as claimed in claim 1, characterised in that the pieces of sawn timber (12) are cut in a manner so as to have a rectangular cross-section the thickness of which is equal to, or smaller than, 80 mm.
9. The method as claimed in claim 1, characterised in that the pieces of sawn timber (12) are supplied as blanks having a length of between 2.5 m and 5.5 m and in that equal lengths of sawn timber (12) are glued together so as to form the laminated construction timber element (11).

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