CA-2988513-C - METHOD OF PRODUCING A LAMINATED WOOD PRODUCT, AND LAMINATED WOOD PRODUCTS

Abstract

The present disclosure provides a method of forming a laminated wood product, which is adapted for receiving a load in a direction perpendicular to a principal fiber direction of the wood. The method comprises cutting a log (2) along the principal fiber direction of the log, into a plurality of wood lamellae (20a, 20b), such that the wood lamellae are formed as radial sections of the log, forming the wood lamellae (20a, 20b) to provide each wood lamella with a trapezoidal cross section, whereby the wood lamellae present a respective planar major base surface (bs1) that is formed at a radially outer part of the log (2) and a respective planar minor base surface (bs2) that is formed at a radially inner part of the log (2), arranging the lamellae (20a, 20b) as at least one layer in which planar major base surfaces (bs1) of immediately adjacent lamellae (20a, 20b) face opposite directions, and gluing together the lamellae (20a, 20b) side surface to side surface (ss1, ss2) such that a wood billet is formed. The method further comprises arranging the wood lamellae (20a, b) such that the major base surfaces (bs1) of immediately adjacent wood lamellae taper in opposite directions, and the gluing comprises wet gluing.

Inventors

• Markus Hirmke

Assignees

• STORA ENSO OYJ

Dates

Publication Date

20260505

Application Date

20160616

Priority Date

20150618

Claims (20)

1. CLAIMS: 1. A method of forming a laminated wood product, which is adapted for receiving a load in a direction perpendicular to a principal fiber direction of the wood, the method comprising: 5 cutting a log along the principal fiber direction of the log, into a plurality of wood lamellae, such that the wood lamellae are formed as radial sections of the log, forming the wood lamellae to provide each wood lamella with a trapezoidal cross section, whereby the wood lamellae present a respective planar major base surface that is formed at a radially outer part of the log and a respective planar minor base surface 10 that is formed at a radially inner part of the log, and to provide each wood lamella with a taper in the principal fiber direction, arranging the lamellae as at least one layer in which planar major base surfaces of immediately adjacent lamellae face opposite directions, and gluing together the lamellae side surface to side surface such that a wood billet is 15 formed, wherein the arranging step includes arranging the wood lamellae by turning every second lamella about 180° about an axis perpendicular to the principal fiber direction of the wood and perpendicular to the major base surface such that the major base surfaces of immediately adjacent wood lamellae taper in opposite directions, and 20 wherein the gluing step comprises wet gluing at a moisture content of the wood lamellae greater than 25% by dry mass.
2. 2. The method as claimed in claim 1, wherein the forming comprises a first forming step, in which the major base surfaces are formed along the outermost part of the log, along a direction which is substantially parallel with the outermost surface of the log. 25
3. 3. The method as claimed in claim 1, wherein the minor base surfaces are formed along a direction which, as seen in a plane containing the pith, presents an angle relative to a pith direction, that is greater than an angle between the major base surface and the outermost surface of the log. Date Rer;ue/Date Received 2022-07-28 84121748 16
4. 4. The method as claimed in claim 1, wherein the forming comprises a second forming step, in which the minor base surfaces are formed by removal of material at a portion of the respective lamella, which is close to the pith, and wherein more of a height of the trapezoidal cross section is removed when forming the minor base surface 5 than when forming the major base surface.
5. 5. The method as claimed in claim 1, wherein the wood lamellae are formed such that a distance, along a surface normal of the base surfaces, between the base surfaces, is at least 50% of a radius of the log.
6. 6. The method as claimed in claim 1, wherein the cutting comprises cutting the 10 wood lamellae to an apex angle of less than 45°.
7. 7. The method as claimed in claim 1, further comprising a step wherein said wood lamellae are subjected to surface drying prior to gluing the wood lamellae together.
8. 8. The method as claimed in claim 7, wherein the surface drying affects the moisture content of the wood lamellae by less than 5%. 15
9. 9. The method as claimed in claim 1, wherein arranging the lamellae comprises arranging the lamellae as a single layer, with base surfaces exposed.
10. 10. The method as claimed in claim 1, further comprising cutting the billet along a plane which is parallel to the principal fiber direction, and perpendicular to the base surfaces, thus forming a plurality of planks. 20
11. 11. The method as claimed in claim 10, further comprising subjecting the planks to a drying step.
12. 12. A method of forming a laminated wood product, which is adapted for receiving a load in a direction perpendicular to a principal fiber direction of the wood, the method comprising: 25 cutting a log along the principal fiber direction of the log, into a plurality of wood lamellae, such that the wood lamellae are formed as radial sections of the log, forming the wood lamellae to provide each wood lamella with a trapezoidal cross section, whereby the wood lamellae present a respective planar major base surface that Date Rer;ue/Date Received 2022-07-28 84121748 17 is formed at a radially outer part of the log and a respective planar minor base surface that is formed at a radially inner part of the log, arranging the lamellae as at least one layer in which planar major base surfaces of immediately adjacent lamellae face opposite directions, and 5 gluing together the lamellae side surface to side surface such that a wood billet is formed, wherein the arranging step includes arranging the wood lamellae such that the major base surfaces of immediately adjacent wood lamellae taper in opposite directions, wherein the gluing step comprises wet gluing at a moisture content of the wood 10 lamellae greaterthan 25% by dry mass, cutting the billet along a plane which is parallel to the principal fiber direction, and perpendicular to the base surfaces, thus forming a plurality of planks, subjecting the planks to a drying step, and joining together at least two of the dried planks in an end-to-end manner, such 15 that a longer plank is formed.
13. 13. A method of forming a laminated wood product, which is adapted for receiving a load in a direction perpendicular to a principal fiber direction of the wood, the method comprising: cutting a log along the principal fiber direction of the log, into a plurality of wood 20 lamellae, such that the wood lamellae are formed as radial sections of the log, forming the wood lamellae to provide each wood lamella with a trapezoidal cross section, whereby the wood lamellae present a respective planar major base surface that is formed at a radially outer part of the log and a respective planar minor base surface that is formed at a radially inner part of the log, 25 arranging the lamellae as at least one layer in which planar major base surfaces of immediately adjacent lamellae face opposite directions, and Date Rer;ue/Date Received 2022-07-28 84121748 18 gluing together the lamellae side surface to side surface such that a wood billet is formed, wherein the arranging step includes arranging the wood lamellae such that the major base surfaces of immediately adjacent wood lamellae taper in opposite directions, 5 wherein the gluing step comprises wet gluing at a moisture content of the wood lamellae greater than 25% by dry mass, cutting the billet along a plane which is parallel to the principal fiber direction, and perpendicular to the base surfaces, thus forming a plurality of planks, and laminating together at least two planks by gluing base surface to base surface. 10
14. 14. The method as claimed in claim 1, wherein the gluing comprises wet gluing at a moisture content of the wood lamellae greater than 30% by dry mass.
15. 15. The method as claimed in claim 1, wherein the wood lamellae are formed such that a distance, along a surface normal of the base surfaces, between the base surfaces, is at least 70% of the radius of the log. 15
16. 16. The method as claimed in claim 1, wherein the cutting comprises cutting the wood lamellae to an apex angle of less than or equal to 36°.
17. 17. The method as claimed in claim 7, wherein the surface drying affects the moisture content of the wood lamellae by less than 1 %.
18. 18. The method as claimed in claim 10, further comprising laminating together at 20 least two joined-together planks by gluing base surface to base surface.
19. 19. A laminated wood product, adapted for receiving a load in a direction perpendicular to a principal fiber direction of the wood, comprising: at least two glued-together wood lamellae, which are formed as radial sections of a log, each having a lamella cross section which is parallel with a cross section of the 25 wood product and a longitudinal direction which is parallel with a longitudinal direction of the wood product and with a principal fiber direction of the wood lamellae, Date Rer;ue/Date Received 2022-07-28 84121748 19 wherein the lamellae present cross sections which are trapezoidal and present a respective planar major base surface that is formed at a radially outer part of the log and a respective minor base surface that is formed at a radially inner part of the log, wherein the major base surfaces of the lamellae are tapered in the longitudinal 5 direction, wherein the lamellae are arranged as at least one layer in which major base surfaces of immediately adjacent lamellae face opposite directions, wherein the major base surfaces of immediately adjacent wood lamellae taper in opposite directions, and 10 wherein the wood lamellae are glued together by a glue suitable for wet gluing at a moisture content of the wood lamellae greater than 25% by dry mass.
20. 20. The laminated wood product as claimed in claim 19, wherein the lamellae are arranged as a single layer, with the base surfaces exposed.

Description

METHOD OF PRODUCING A LAMINATED WOOD PRODUCT. AND LAMINATED WOOD PRODUCTS Technical Field The present disclosure relates to a structural member, which may be used as a beam, a joist, a stud, a pillar or the like. The disclosure also relates to a method of producing the structural member. Background Currently, glue-laminated beams ("gluelam") in Europe are mostly produced according to DIN 1052:2008 (German standard) or DIN EN 14080: 2013-09 (harmonized European standard). The beams are built up with 10 visually graded or machine graded boards, which are produced and kiln-dried in sawmills in the traditional way. The gluelam producer takes these boards as raw material, grades them and produces the required lamellae by cutting out defects (e.g. knots) and finger-jointing the pieces together. After the finger-jointed lamellae have 15 been planed, glue is applied and the beam is formed by gluing the lamellae together. The final steps may comprise planing the beam, removing optical defects, packaging and loading it. Hence, traditionally, timber is sawn into planks or lamellae according to the scheme depicted in Fig. 1 of US5816015, which discloses alternative 20 methods of forming wood beams by laminating together a plurality of planks or lamellae. EP1277552A2 discloses a similar method of forming a wood beam by cutting a round piece of timber into a plurality of strips having a trapezoidal cross section and laminating together the pieces thus formed into a beam. 25 US4122878 discloses a method of converting balsa wood of relatively small diameter into panels. There is still a need to provide improved use of the timber raw material, as well as a need for beams having improved strength and/or reduced variation in strength between different beams. 2 Summary It is a general object of the present invention to provide an improved structural member, such as a beam, a joist, a stud, a pillar or the like. A 5 particular object includes the provision of a structural member which makes better use of existing raw materials and which is stronger. Further objects include the provision of improved control of the production process of structural members, such that properties of resulting members will present less variation. 10 The invention is defined by the appended independent claims, with embodiments being set forth in the dependent claims and in the following description and drawings. According to a first aspect, there is provided a method of forming a laminated wood product, which is adapted for receiving a load in a direction 15 perpendicular to a principal fiber direction of the wood, the method comprising cutting a log along the principal fiber direction of the log, into a plurality of wood lamellae, such that the wood lamellae are formed as radial sections of the log. The method further comprises forming the wood lamellae to provide each wood lamella with a trapezoidal cross section, whereby the wood 20 lamellae present a respective planar major base surface that is formed at a radially outer part of the log and a respective planar minor base surface that is formed at a radially inner part of the log, arranging the lamellae as at least one layer in which planar major base surfaces of immediately adjacent lamellae face opposite directions, and gluing together the lamellae side 25 surface to side surface such that a wood billet is formed. The method further comprises arranging the wood lamellae such that the major base surfaces of immediately adjacent wood lamellae taper in opposite directions. The gluing comprises wet gluing. The term "major base surface" is defined as the greater one of the two 30 base surfaces of a body having a trapezoidal cross section. Likewise, the "minor base surface" is defined as the smaller one of the base surfaces of a body having trapezoidal cross section. 3 The term "wet gluing" is defined as gluing at a moisture content of the wood lamellae greater than 25 % by dry mass, preferably greater than 30 % by dry mass. The moisture content is calculated in relation to the mass of the dry 5 wood, i.e. moisture content = (mass of wet wood - mass of dry wood)/(mass of dry wood). A glue that is suitable for wet gluing may be a polyurethane based glue. The forming may comprise a first forming step, in which the major base 10 surfaces are formed along the outermost part of the log, preferably along a direction which is substantially parallel with the outermost surface of the log. By "substantially parallel" is understood that there is an angular deviation of less than 3°, preferably less than 2° or less than 1 °. The minor base surfaces may be formed along a direction which, as 15 seen in a plane containing the pith, presents an angle relative to a pith direction, that is greater than an angle between the major base surface and the outermost surface of the log. The forming may comprise a second forming step, in which the minor base surfaces are formed by removal of material at a portion of the respecti