SE542164C2

SE542164C2 - Laminated wood products and methods of their manufacture

Info

Publication number: SE542164C2
Application number: SE1551391A
Authority: SE
Inventors: Hermann Kirchmayr; Markus Hirmke; Philipp Sauer
Original assignee: Stora Enso Oyj
Priority date: 2015-10-28
Filing date: 2015-10-28
Publication date: 2020-03-03
Also published as: EP3368254A1; EP3368254B1; EP3368254C0; EP3368254A4; SE1551391A1; WO2017072687A1

Abstract

The present disclosure provides a laminated wood product (260, 260’, 261', 271, 271', 280) for use as a construction element. Such a product comprises a plurality of adjacent wood lamellae (20a, 20b), each having a longitudinal direction which is substantially parallel with a principal fiber direction of the respective wood lamella, and a generally trapezoidal cross section providing a major base surface (bs1), a minor base surface (bs2) and a pair of opposing side surfaces (ss1, ss2). The lamellae are glued together side surface (ss1) to side surface (ss2), such that major base surfaces (bs1) of immediately adjacent lamellae face opposite directions. The major base surfaces (bs1) define respective major surfaces of the wood product. A thickness of the wood product, as seen in a direction perpendicular to the major surfaces, is about 6-30 cm, preferably 8-26 cm.

Description

LAMINATED WOOD PRODUCTS AND METHODS OF THEIR MANUFACTURE Technical Field The present disclosure relates to wood-based construction components and methods of their manufacturing. In particular, the disclosure relates to construction components which make better use of the raw material and/or which provide enhanced strength properties as compared to conventional construction components.

The disclosure relates to laminated elements for making ceilings and/or floors.

Background Engineered wood products, i.e. products which are made up of a plurality of wood pieces that are glued together, are known as such.

Examples of engineered wood products include floor and ceiling elements, glulam beams and joists, rib slabs and plywood boards.

Such engineered wood products are typically provided by a process wherein a wood log is sawn according to a cross sectional pattern of mutually orthogonal cuts, after which the thus provided planks are dried, formatted (planed), graded and then glued together.

One disadvantage of such engineered wood products is the waste of material provided by the mismatch between log’s natural generally circular cross section and the orthogonal cut-based sawing pattern traditionally used.

Another disadvantage of such engineered products is that the orthogonal cut-based sawing pattern results in wood pieces having different strength and/or warp properties.

There is a general need for engineered wood products which make better use of the raw material, such that less waste of material is provided and wood products having better strength and warp properties can be provided.

Summary It is a general object of the present disclosure to provide engineered wood products, which make better use of the raw material and which have better strength than comparative (in terms of weight and volume) existing engineered wood products.

The invention is defined by the appended independent claims.

Embodiments are set forth in the appended dependent claims, in the following description and in the attached drawings.

According to a first aspect of a first concept, there is provided a laminated wood product for use as a construction element, comprising a plurality of adjacent wood lamellae, each having a longitudinal direction which is substantially parallel with a principal fiber direction of the respective wood lamella, and a generally trapezoidal cross section providing a major base surface, a minor base surface and a pair of opposing side surfaces. The lamellae are glued together side surface to side surface, such that major base surfaces (bs1) of immediately adjacent lamellae face opposite directions. The major base surfaces (bs1) define respective major surfaces of the wood product. A thickness of the wood product, as seen in a direction perpendicular to the major surfaces, is about 6-30 cm, preferably 8-26 cm.

A laminated wood product as described above can be used as a wall, roof, floor or ceiling element, making optimum use of the portions of the wood having the highest strength while at the same time minimizing waste of material.

The lamellae may present year rings, wherein year rings at the major base surface have a greater bending radius than year rings at the minor base surface.

An edge portion of the wood product may present means for mechanically connecting the wood product in at least one direction to another identical wood product.

The edge portion may be the long side edge portion (parallel with the longitudinal direction of the wood lamellae) and/or the short side edge portion, which may be perpendicular to the long side edge portion.

The connecting means may comprise at least one of a tongue and/or a groove extending substantially parallel with the base surfaces for providing a mechanical connection in a direction perpendicular to the base surfaces, and locking member extending substantially perpendicular to the base surfaces for providing a mechanical connection in a direction parallel with the base surfaces and perpendicular to the longitudinal direction.

Hence, mechanical locking may be provided for preventing adjacent laminated wood products from separating in an out-of-plane direction (typically vertically, when used as floor or ceiling element) and/or in an inplane direction (typically horizontally).

At least some major and minor base surfaces, which are provided by a pair of immediately adjacent lamellae, and which face the same direction, are situated in spaced apart planes.

Such laminated wood products may present an enhanced ratio of height and/or stiffness to weight.

The base surfaces may taper along said longitudinal direction.

Such lamellae provide optimal use of the raw material.

Alternatively, the base surfaces may present a substantially constant width along the longitudinal direction.

Such lamellae may be easier to produce, especially from a population of logs with varying diameter.

The wood lamellae are glued together by means of a glue that is suitable for wet gluing.

Wet gluing, e.g. using a urethane or polyurethane based glue, has proven to be an effective way of gluing together wood that has not been subjected to drying. While the drying process often causes some warping, which means that formatting of the dried wood pieces may be necessary prior to gluing, wet gluing will reduce the waste of material by making use of the format achieved in the sawing of the log when producing the billet.

According to a second aspect, there is provided a method of making a laminated wood product for use as a ceiling or floor element having major surfaces and a thickness as seen in a direction perpendicular to the major surfaces, of about 6-30 cm, preferably 8-26 cm. The method comprises providing a plurality of wood lamellae, each having a longitudinal direction which is substantially parallel with a principal fiber direction of the respective wood lamella, and a generally trapezoidal cross section providing a major base surface, a minor base surface and a pair of opposing side surfaces, applying glue to the side surfaces, arranging the wood lamellae side surface to side surface (ss2), such that major base surfaces of immediately adjacent lamellae face opposite directions and the base surfaces define the respective major surfaces of the wood product, pressing the side surfaces towards each other for a sufficient time to bond the wood lamellae to each other to form a billet, and optionally cutting the thus formed billet along a plane parallel with the longitudinal direction and perpendicular to the major surfaces to form a plank.

The method may further comprise subjecting the wood lamellae to a drying step prior to the application of glue.

The method further comprises subjecting the billet to a drying step subsequent to the bonding.

The method may further comprise forming locking means along at least one long side edge of the plank.

According to a third aspect, there is provided use of a laminated wood product as described above as a wall, roof, floor or ceiling element.

Such a wall, roof, floor or ceiling element may be a load bearing element.

Brief Description of the Drawings Figs 1a-1h schematically illustrate a method of making an intermediate product in the form of a billet.

Fig 2a is a schematic side view of a system for producing wood lamellae Fig. 2b is a schematic sectional view taken along line A-A of Fig. 2a. Figs 3a-3b schematically illustrate a billet formed according to an alternative method.

Figs 4a-4f schematically illustrate a method of making a construction element which is useful for making ceilings and/or floors.

Figs 5a-5d schematically illustrate an alternative method of making a construction element, which is useful for making ceilings and/or floors.

Figs 6a-6i schematically illustrate a method of making load bearing construction elements.

Figs 7a-7f schematically illustrate a method of making panels.

Figs 8a-8e schematically illustrates a method of making a single ply board.

Figs 9a-9b schematically illustrates a method of making a multi-ply board.

Figs 10a-10h schematically illustrates methods of making a pillar or an arcuate structure.

Detailed Description The description will initially be directed to a new method of making a wood billet. This wood billet forms the starting material for making the laminated wood product which will be described with reference to the subsequent drawings.

The machine concept is merely one example of a way of producing such lamellae, and is not intended to limit the scope of protection.

Fig. 1a schematically illustrates a log 2, which has been cut longitudinally into two halves 2’. The log 2 may have been debarked prior to this cutting. The cutting may be performed by any type of cutting device, such as, but not limited to, a saw, e.g. a circular saw or a band saw.

Fig. 1b schematically illustrates a log half 2’ after it has been provided with a longitudinally extending groove 23 along its pith and cut longitudinally into six radial sections 2"a, 2"b, as will be further described with reference to Figs 2a-2b.Fig. 1c schematically illustrates processing of one of the radial sections 2"a, 2"b into a lamella 20a, 20b. The lamella 20a, 20b is subjected to forming of base surfaces bs1, bs2, to form a lamella 20a, 20b, which will present a trapezoidal cross section.

The base surfaces bs1, bs2 thus formed comprise a major base surface bs1, which is formed by tool 31 closest to the bark of the log and along the bark side. The base surfaces further comprise a minor base surface bs2, which is formed close to the pith and parallel with the major base surface bs1 by tool 32.

The tools 31, 32 may be any type of tool capable of forming a planar surface, including but not limited to milling cutters, circular saw blades or band saw blades.

The first tool 31, which forms the major base surface bs1, is arranged to use the bark side as reference, such that the major base side bs1 is formed along a direction parallel with the bark side.

The second tool 32, which forms the minor base surface bs2, is arranged to use the major base surface and/or the bark side as a reference, such that the minor base surface bs2 is formed along a direction parallel with the major surface and/or the bark side.

The cross section of the lamellae 20a, 20b is trapezoidal having a constant height. With the major base surface bs1 being formed substantially parallel with the bark, and with the log presenting a frusto-conical shape, it is recognized that the major base surface bs1 will taper along the central direction of the log C. That is, the log will taper in a direction towards the top of the tree from which it was formed. This direction is also parallel with the principal fiber direction of the log and of the wood lamellae.

Moreover, the minor base surface bs2 will also taper along the central direction C of the log.

The fact that the radius of the log would also diminish towards the top of the tree from which it was formed, implies that while the amount of material removed at the bark side, by tool 31, in the forming of the major base sides bs1 will be substantially constant along the length of the lamella 20a, 20b, as seen in the radial direction.

However, the amount of material removed at the pith side, by tool 32, will diminish towards as seen in the direction towards the top of the tree from which the lamella 20a, 20b was formed.

Referring to Fig. 1 d, after the lamellae 20a, 20b have been formed, each lamella will have a major and a minor base surface bs1, bs2 and a pair of side surfaces ss1, ss2, which will be identical.

Referring to Fig. 1e, every second lamella 20b will now be turned or flipped about 180° about its longitudinal axis and about 180° about an axis perpendicular to the longitudinal axis and perpendicular to the major base surface bs1, such that the lamellae will become positioned as illustrated in Fig. 1e. That is, the directions of taper Ca and Cb will extend in opposite directions.

At this point, the base surfaces of every pair of adjacent wood lamellae 20a, 20b will taper towards substantially opposite directions. Moreover, major base surfaces bs1 of every pair of adjacent wood lamellae will face substantially opposite directions, i.e. one upwards in Fig. 1e and the other one downwards in Fig. 1e.

At this point, the wood may still be "wet", that is, its moisture content may be more than 25 % by dry mass, preferably more than 30 %. Hence, the wood has not been subjected to any accelerated or intentional drying, such as kiln drying. When wet gluing, it is recommended to reduce the amount of free water on the wood surface to a minimum. Hence, a brief surface drying step, basically having no effect except for on the very surface, may be performed, e.g. by means of a fan. Fig. 1f schematically illustrates the two lamellae 20a, 20b when arranged adjacent each other, side surface ss1 to side surface ss2 and with base surfaces bs1, bs2 of the pair of thus adjacent lamellae 20a, 20b tapering in opposite directions.

Referring to Fig. 1 g, there is illustrated a pair of glue applicators 33a, 33b, which apply glue to side surfaces of lamellae 20a, 20b, respectively. A single, or even more, glue applicators may be used.

The lamellae are then arranged as illustrated in Fig. 1 g, i.e. with the base surfaces bs1, bs2 of every pair of adjacent wood lamellae 20a, 20b tapering towards substantially opposite directions and major base surfaces bs1 of every pair of adjacent wood lamellae facing substantially opposite directions.

The glue used is a glue adapted for wet gluing wood, such as a water activated glue. One example of such glue is a polyurethane (PU) based glue.

The lamellae 20a, 20b will be subjected to a pressing tool 34 pressing the lamellae 20a, 20b together in directions perpendicular to the base surfaces 20a, 20b and/or parallel with base surfaces 20a, 20b and perpendicular to the longitudinal axes C.

Depending on the design of the pressing equipment, the billet 200 that is formed may be of a predetermined length or it may be continuous in a direction perpendicular to the lamellae fiber direction and parallel with the base surfaces bs1, bs2, that is, lamellae are added to one end of the billet and fed into the press while at the output side of the press, pieces of the billet 200 are sawn off at predetermined intervals.

As illustrated in Fig. 1h, after the gluing process, an intermediate wood product, here referred to as a "billet" 200 is provided, made up of wood lamellae 20a, 20b glued together first side surface ss1 to first side surface ss1 and second side surface ss2 to second side surface ss2.

The billet illustrated in fig 1h does not form part of the claimed invention.

In the illustrated example, the billet 200 consists of a single layer of lamellae 20a, 20b, which are arranged side surface to side surface and with major base surfaces bs1 of immediately adjacent lamellae facing opposite directions and with base surfaces bs1, bs2 of immediately adjacent lamellae tapering in width in opposite directions.

It is noted that an alternative billet may be produced from logs which are sawn according to Figs 1a-1b and wherein the lamellae are formed with the pith side as a reference. Such lamellae may have constant cross section, such that base surfaces will be rectangular rather than tapering in width.

Fig. 2a is a schematic side view of a device 300 for producing wood lamellae 20a, 20b from a half-log 2’. The device comprises a groove cutter 311 and a set 312 of radial cutters 321a, 321b, 321c, 321d and 321e.

Moreover, the device 300 may comprise a conveyor arrangement 300a, 300b, 300c for causing relative movement between the log and the cutters 311, 312. Typically, the log may be moved relative to stationary cutters 311, 312.

However, it is also possible to provide cutters 311, 312, which are capable of moving along the length of the half-log 2'.

The half log 2’ has typically been longitudinally cut in half prior to being introduced into the device 300. That is, the log has been cut longitudinally along a plane containing a central axis C of the log. The log may have been pre-cut into an appropriate length, such as 1-10 m, preferably 1-5 m, 1-3 m or 1-2 m. Moreover, the log may have been wholly or partially debarked. Hence, the log can be said to present a planar surface 22 and a convex surface 21. For practical reasons, the log may be conveyed with its planar surface facing downwardly and oriented horizontally.

Fig. 2b is a cross sectional view taken along line A-A in Fig. 2a. In Fig. 2b, it is illustrated how the groove cutter 311 provides a longitudinal groove at the central portion of the log, i.e. at the pith area.

The groove cutter 311 may be formed as a circular, rotatable cutter having a cutting edge with a cross section that corresponds to a desired cross section of the groove 23.

The groove 23 formed by the groove cutter 311 may presents a substantially concave surface, which may be substantially half circular, or which may be polygonal.

The groove cutter 311 may extend upwardly from a support on which the log is to be supported with its planar surface 22 facing downwardly.

Figs 3a-3b illustrate an alternative way of forming a billet.

Referring to Figs 3a-3b, it is noted that lamellae 25a, 25b may also be formed using the pith side as a reference, in which case a constant cross section may be achieved and the base surfaces will be substantially rectangular, without taper.

The lamellae may be glued together when in the wet state, as described above, or in a dry state, potentially subsequent to a forming operation, such as planing.

As illustrated in Fig. 3a, such lamellae may be individually joined by joints J1, which may be finger joints or the like, so as to provide extended lamellae 26a, 26b, which each is made up of a plurality of lamellae 25a; 25b.

As illustrated in Fig. 3b, such lamellae 25a, 25b or extended lamellae 26a, 26b may be used to form a billet 260, which is similar to the billet 200 previously discussed.

This billet 260 may be provided with reinforcements R1, which may extend perpendicular to the longitudinal direction of the lamellae and in parallel with the principal surface.

Such reinforcements R1 may be provided by a rod made of wood or polymer material, that is, preferably a material which can be sawn without causing damage to the sawing equipment. The reinforcement may be bonded to the structure by glue. It is also possible to make the reinforcement from a metallic material.

Such reinforcements may be useful and optional for any type of billet described herein.

The billet illustrated in figs 3a-3b does not form part of the claimed invention. Referring to Figs 4a-5d, the description will now focus on a construction element and a method of its fabrication. Such construction elements may be used as a floor or ceiling element, or as a wall or roof element. Yet another use may be as a noise reduction wall.

The billet illustrated in figs 4a-4f does not form part of the claimed invention.

Fig. 4a schematically illustrates a billet 200, which may be the result of the process described with reference to Figs 1a-1h.

Such a billet, when formed to a suitable thickness, may be used as a ceiling or floor element. Typical thicknesses for such floor or ceiling elements may be on the order of 50-300 mm. Particular thicknesses may be 80, 100, 120, 140, 160, 180, 200, 220, 240 or 260 mm, with a tolerance of /- 5 %, preferably /- 2 %, /- 1 % or /- 0.5 %.

The billet may have a width which may be on the order of 50-150 cm. For example, the billet may be produced to provide a standard width, such as 62 cm or 62.5 cm. the billet may also be produced with a width forming a multiple (x2, x3, x4, etc) of such a standard width. Preferably, the width may be on the order of 50-100 cm, e.g. 60-80 cm.

The billet may be produced to any length. Typical lengths for elements of the present type may be up to 15 m. Lengths may vary from 2-15 m, preferably 3-15 m, 3-10 m, 5-15 m or 5-10 m.

Referring to Fig. 4b, in order to provide a construction element 260, such as a floor or ceiling element, having a desired length, billets 261 may be joined by means of any type of joint J2, such as a finger joint, in a per se known manner. Many different types of finger joints are known. The fingers of the joint may extend in any direction, including parallel with the principal plane of the billet or orthogonal to the principal plane of the billet.

Referring to Fig. 4c, the billet 26T or construction elements 260’ may be provided with mechanical locking devices J3a, J3b for providing mechanical interconnection between identical floor or ceiling elements.

As illustrated, such mechanical locking devices J3a, J3b may provide mechanical connection in a direction perpendicular to the principal plane of the floor or ceiling element.

Moreover, such mechanical locking devices may give room for such shrinkage and/or swelling as occurs as a consequence of variations in humidity and temperature.

The locking devices prevent the formation of gaps (or at least visible gaps) between elements, thus enhancing appearance and preventing draft or spreading of fire.

In the particular example, the locking devices J3a, J3b comprise a tongue and groove joint (the function of which is known per se), which here includes a pair of tongues and a matching pair of grooves. It is recognized that other types of locking devices for providing mechanical interconnection perpendicular to and/or parallel with the principal plane can be provided. Inspiration for such locking devices may be found in the field of mechanically interconnectable floor panels.

In the particular example, the mechanical locking devices J3a, J3b extend along long side edges of the floor or ceiling element, i.e. substantially parallel with a principal fiber direction of the wood lamellae making up the billet(s).

It is conceivable to also provide mechanical locking devices on short side edges of the floor or ceiling elements. Such short side mechanical locking devices may be identical with, or different from, the ones provided on the long sides.

Moreover, it is conceivable also to provide mechanical interconnection in a direction perpendicular to the joint edge, i.e. typically horizontally when the panel is used as a floor or ceiling element. Hence, adjacent panels can be prevented from separating horizontally from each other. As is known in the flooring industry, it may be desirable to provide a stronger such horizontal joint on short side edges than on long side edges.

Fig. 4d illustrates, in cross section, a pair of interconnected floor construction elements of the kind described in Fig. 4c.

Glue may, but need not, be applied to the locking device(s) before the floor or ceiling elements are joined by a horizontal movement whereby the tongue is driven into the groove.

Fig. 4e schematically illustrates an alternative mechanical locking device, which is based on the floor or ceiling elements being formed with grooves J3a on both long sides, wherein a separate tongue J3c is inserted into the grooves and the floor or ceiling elements are interconnected as described with respect to Fig. 4d.

The separate tongue may be formed of a wood material, which may be the same or different from that of which the floor or ceiling elements are formed. For example, it is possible to use a wood material having better strength properties. Alternatively, the separate tongue may be formed of a polymer material, a wood based material (MDF, HDF, particle board, chip board, plywood) or even a metallic material.

Fig. 4f schematically illustrates a construction element 280 which has been formed from a plurality of elongate planks 260, which are formed from planks 261 that are joined in an end-to end manner, just like illustrated in Fig. 4b, by means of a joint J2, which may be a finger joint or the like.

In Fig. 4f, however, at least two such elongate planks 260 are joined along a plane that is parallel with the longitudinal direction and perpendicular to the principal plane.

Moreover, joints J2, such as finger joints, of immediately juxtaposed elongate planks 260 are offset relative one another in the longitudinal direction. The offset may correspond to 5-50 % of a length of the planks 261, preferably 10-30 % of said length.

Such a construction element 280 may present enhanced strength as compared to the ones illustrated in Fig. 4b.

Figs 5a-5d schematically illustrate another embodiment of a construction element, such as a floor or ceiling element 270.

As is shown in Fig. 5a, the billet is formed differently from that of Fig. 4a in that adjacent lamellae 25a, 25b are slightly offset in a direction perpendicular to the principal plane of the floor or ceiling element 270.

For example, the lamellae 25a, 25b may be offset by a distance corresponding to 1-50 % of the lamellae height, preferably 5-30 % or 10-20 %.

Hence, the construction elements 270, 271 thus formed will not have a smooth upper surface but one with grooves. Such grooves may, but need not, be filled with a filler, e.g. an expanding/foaming filler.

As illustrated in Figs 5b-5d, this billet formed into elongate construction elements 271' by cutting cuts S3, lengthwise joining J4 and forming of mechanical locking devices J5 just like the one illustrated in Fig. 4a.

Offset arrangements such as illustrated in Fig. 4f is also possible.

Referring to Figs 6a-6f, the description will now focus on a beam and a method of its fabrication.

The method and products described with reference to figs 6a-6f do not form part of the claimed invention. Fig. 6a schematically illustrates an I- or H-beam 500, the flange portion 502, 503 of which is formed from a billet of the type disclosed in Fig. 1h. The web portion 501 of this beam may be formed by any type of sheet shaped material, such as wood material, wood based material, polymer material (including reinforced/composite polymer material) or even metallic material.

The beam illustrated in Fig. 6a thus comprises a pair of flange portions 502, 503 including a plurality of adjacent wood lamellae 20a, 20b, each having a longitudinal direction which is substantially parallel with a principal fiber direction of the respective wood lamella, and a generally trapezoidal cross section providing a major base surface bs1, a minor base surface bs2 and a pair of opposing side surfaces ss1, ss2. In the flange portion, the lamellae are glued together side surface ss1 to side surface ss2, such that major base surfaces bs1 of immediately adjacent lamellae face opposite directions. The major base surfaces bs1 define respective major surfaces of the flange portion.

The web portion may be connected to the flange portion by means of glue. Optionally, a mechanical connection may be provided, including a tongue and groove joint, a finger joint (extending along a length direction of the beam), a plurality of fasteners, such as wood plugs, polymer plugs, nails or screws.

It is noted that the beam 500 may be designed with only one flange 502, 503 portion and that other beam configurations may be provided, including L-beams and W-beams.

It is noted that the beam 500 of Fig. 6a may be formed from a billet provided from lamella having tapering (lamellae 20a, 20b) or rectangular (lamellae 25a, 25b) base surfaces.

The beam 510 illustrated in Fig. 6b is formed with each flange portion 512, 513 provided from a single wood lamella having a longitudinal direction which is substantially parallel with a principal fiber direction of the wood lamella, and a generally trapezoidal cross section providing a major base surface bs1, a minor base surface bs2 and a pair of opposing side surfaces ss1, ss2.

The flange portions 512, 513 may be attached to the web portion 511 in the same manner as disclosed with respect to Fig. 6a.

In this embodiment, it is preferred that the wood lamellae present rectangular base surfaces.

The beam 520 illustrated in Fig. 6c is formed with only flange portions 522, 523 according to the same principle as the one in Fig. 6b, but with no separate web portion.

Instead, the tapering cross section of the lamellae provides the narrower "web-like" portion of the beam in Fig. 6b.

The interconnection of the lamellae may be provided according to the same principles as for the connection to the web in Figs 6a and 6b.

The beam 530 illustrated in Fig. 6d is very similar to the one disclosed in Fig. 6a, but with each flange portion 532, 533 formed of three adjacent wood lamellae 20a, 20b, each having a longitudinal direction which is substantially parallel with a principal fiber direction of the respective wood lamella, and a generally trapezoidal cross section providing a major base surface bs1, a minor base surface bs2 and a pair of opposing side surfaces ss1, ss2. In the flange portion, the lamellae are glued together side surface ss1 to side surface ss2, such that major base surfaces bs1 of immediately adjacent lamellae face opposite directions. The major base surfaces bs1 define respective major surfaces of the flange portion.

The flange portions 532, 533 present a width that tapers towards the web, which is a consequence of the fact that the two outer lamellae are arranged with their major base surfaces facing away from the web portion, while the major base surface of the respective middle lamella faces, and is connected to, the web portion.

The flange portions 532, 533 may be attached to the web portion 531 in the same manner as disclosed with respect to Fig. 6a.

Fig. 6e schematically illustrates a beam which is very similar to that of Fig. 6d, but where the flange portion is provided from at least two layers of adjacent wood lamellae 20a, 20b, each having a longitudinal direction which is substantially parallel with a principal fiber direction of the respective wood lamella, and a generally trapezoidal cross section providing a major base surface bs1, a minor base surface bs2 and a pair of opposing side surfaces ss1, ss2. In the flange portion, the lamellae are glued together side surface ss1 to side surface ss2, such that major base surfaces bs1 of immediately adjacent lamellae face opposite directions. The layers are connected to each other base surface to base surface. The connection may be provided by glue or in the same manner as disclosed with respect to Fig. 6a regarding the attachment of the flange portion to the web portion.

The flange portions 542, 543 present a width that tapers towards the web, which is a consequence of the fact that the two outer lamellae are arranged with their major base surfaces facing away from the web portion, while the major base surface of the respective middle lamella faces, and is connected to, the web portion 541.

The flange portions 542, 543 may be attached to the web portion 541 in the same manner as disclosed with respect to Fig. 6a.

It is noted that an arbitrary number of layers may be provided for each flange portion.

Fig. 6f discloses a sandwich construction 550, wherein a number of beams 552, 553, which can be formed as disclosed with reference to any one of Figs 6a-6e, are sandwiched between a pair of boards 554, 555.

The boards 554, 555 may be provided from any type of board material, including wood material, wood based material, polymer material (including reinforced/composite polymer material) or even metallic material.

In particular, the boards may be formed from the single-ply or multi-ply materials that are discussed with respect to Figs 1h, 4a-4e, 5a-5d, 8a-8d or 9a-9b.

The beam portion(s) may be connected to the board by glue and/or by means of mechanical fastening devices, including tongue-and-groove or finger type joints, wood plugs, fasteners (screws, nails) etc.

Fig. 6g-6h schematically illustrate a reinforced beam 560, 560’, comprising a reinforcement element 565, which extends at an angle less than 45° to the principal transverse load direction. Preferably, the reinforcement elements extends at an angle less than 30°, less than 20°, less than 10° or about parallel with the principal transverse load direction.

The reinforcement element may extend at least partially through at least one of the flange portions, preferably at least partially through both. Moreover, where the beam presents a web portion, the reinforcement element may extend through this web portion as well.

The reinforcement element may be formed of wood or polymer material, that is, preferably a material which can be sawn without causing damage to the sawing equipment. Preferably, the reinforcement may be formed of a wood material having greater strength than the wood from which the beam is formed.

The reinforcement may be bonded to the structure by glue. It is also possible to make the reinforcement from a metallic material.

It is possible to provide a plurality of reinforcement elements along the length of a beam. For example it may be possible to provide 1-10 reinforcement elements per meter in length.

Each reinforcement element 565 may have a diameter of about 5-50 mm, preferably about 15-40 or about 20-30 mm. A length of the reinforcement element may be on the order of 70-100 % of a thickness of the beam as seen in a direction of insertion of the reinforcement element.

Referring to Fig. 6g, a joint 566 between the flange portions 562, 563 may be have the form of a finger joint, having fingers with a height corresponding to 10-50 % of a height of the flange portion 562, 563, preferably about 15-30 %.

Referring to Fig. 6h, side portions of the flange portions may be cut away so as to provide side surfaces 5621, 5631, which are substantially flat and substantially perpendicular to the principal load bearing surface of the beam.

Referring to Fig. 6i a plurality of beams 560’ such as the one illustrated in Fig. 6h may be arranged side by side with side surfaces 5621, 5631 contacting each other, in a juxtaposed manner and joined to each other, e.g. by glue, such that a slab like structure 570 is formed.

Reinforcement elements such as described with respect to Figs 6g-6i may be used with any of the beams disclosed with respect ot Figs 6a-6f.

Referring to Figs 7a-7f, the description will now focus on a rib slab 600, 620, 630, 630’, 640 and on a method of its fabrication. A rib slab is essentially a light weight construction element intended for providing a floor or a ceiling. That is, the construction element is light weight in the sense that it is a composite structure formed of a board and a plurality of reinforcing elements in such a way that the structure will provide voids, thus reducing weight.

The method and products described with reference to figs 7a-7f do not form part of the claimed invention.

In Fig. 7a, there is illustrated a basic version of a rib slab 600, comprising a panel portion 601 and a plurality of rib portions 602, 603.

The panel portion 601 may be provided from any type of board material, including wood material, wood based material, polymer material (including reinforced/composite polymer material) or even metallic material.

In particular, the panel portion 601 may be formed from the single-ply or multi-ply materials that are discussed with respect to Figs 1h, 4a-4e, 5a-5d, 8a-8d or 9a-9b.

The rib portions 602, 603 may be provided from wood lamellae, each having a longitudinal direction which is substantially parallel with a principal fiber direction of the wood lamella, and a generally trapezoidal cross section providing a major base surface bs1, a minor base surface bs2 and a pair of opposing side surfaces ss1, ss2.

The rib portions 602, 603 may be arranged to extend substantially parallel to each other and laterally spaced apart. The lateral spacing may be determined based on the strength requirement of the respective rib slab.

Typical spacing may be on the order of 1-5 times a width of the major base surfaces of the lamellae, preferably 1-2 times.

The panel portion 601 may be connected to the rib portions by means of glue. Optionally, a mechanical connection may be provided, including a tongue and groove joint, a finger joint (extending along a length direction of the beam), a plurality of fasteners, such as wood plugs, polymer plugs, nails or screws.

The rib portions 602, 603 may be connected to the panel portion by their major base surfaces bs1 or by their minor base surfaces bs2.

As an alternative, the rib portions 602, 603 may be connected to the panel portion alternatingly by major base surfaces bs1 and minor base surfaces bs2.

Fig. 7b schematically illustrates a rib slab 610 which may be formed just like the one in Fig. 7a, but with a pair of panel portions 601, 604 sandwiching the rib portions 602, 603. The forming of the rib slab in Fig. 7a may be the first step of forming the rib slab of Fig. 7b.

Fig. 7c schematically illustrates a rib slab 620 comprising three panel portions 601, 604, 605 and two layers of rib portions 602, 603; 612, 613, wherein rib portions and panel portions are arranged alternatingly, as seen in a direction perpendicular to the principal face of the rib slab. Forming of the rib slab 600, 610 as illustrated in Figs 7a and/or Fig. 7b may be the first step or steps in the forming of the rib slab of Fig. 7c.

Fig. 7d schematically illustrates a rib slab 630, comprising an upper part 601, 602, 603 which is formed like the one illustrated in Fig. 7a, and a lower part 632, 633, which is suspended from the upper part 601, 602, 603. The lower part 631, 632, 633 may also comprise a panel portion 633 and a rib portion 632. The panel portion 633 may be formed of any of the materials previously discussed for panel portions.

The rib portion 632 may be formed by a plurality of lamellae, each having a longitudinal direction which is substantially parallel with a principal fiber direction of the wood lamella, and a generally trapezoidal cross section providing a major base surface bs1, a minor base surface bs2 and a pair of opposing side surfaces ss1, ss2.

In the lower part 631, 632, 633, at least some lamellae are connected to the panel portion by their minor base surfaces bs2, such that the lamellae provide undercut edges.

These lamellae may be positioned such that their undercut edges can engage correspondingly arranged undercut edges of rib portions 603 of the upper part, such that the lower part is suspended from the upper part.

In particular, a pair of adjacent lamellae 631, 632 at the lower portion may be arranged such that their respective undercut edges engage a respective undercut edge of a rib of the upper part. That is, a rib which is connected to the panel portion of the upper part by its minor base surface.

The connection between the upper and lower portions may be entirely mechanical, i.e. without glue.

Such a rib slab 630 can be used to reduce impact sound and other sounds which would be transmitted through coupling, for example through a ceiling. In particular it may reduce propagation of impact noise in the vertical direction, past the rib slab, such as between floors of a building.

Fig. 7e schematically illustrates a rib slab 640 which is formed according to the principles set forth above, but with a higher density of rib portions 641, which are laterally spaced with a distance (at the lamella major base surface) which is less than the width of the lamella major base surface, preferably on the order of 10-90 % of the width of the lamella major base surface.

Such a rib slab 640 can be used to reduce noise, especially in the space below the rib slab and in particular reverberation-related noise. Hence, it may be used to provide a noise attenuating, yet decorative, ceiling.

Fig. 7f schematically illustrates a rib slab 630’, which is similar to the one disclosed in Fig. 7d, but wherein a sound attenuating device 635 is arranged between contact surfaces between the beams 602 and 631, 632.

This sound attenuating device 635 may extend over all or part of the contact surfaces (i.e. the surfaces that would have contacted each other but for the sound attenuating device 635).

The sound attenuating device may be formed of a material having reduced sound coupling properties as compared to the material from which the beams are formed. For example, the sound attenuating device may be formed of a rubber elastic material, such as rubber, thermoplastic elastomer, polyurethane, combinations thereof, or the like. As other options, the sound attenuating device may comprise an expanded polymer material, a wood fiber material (including pulp based materials), a 2D or 3D woven or nonwoven material, or a soft natural material, such as leather, sponge, or the like.

Hence, the sound attenuating device may be a separate part, which is arranged between and optionally adhered to the beams.

As another alternative, the sound attenuating device may be formed in situ, e.g. by means of extrusion of a cooling, hardening, setting, cross-linking and/or foaming composition Figs 8a-8e schematically illustrate a method of forming a board material from a billet, such as the one disclosed in Fig. 1h.

The method disclosed in figs 8a-8e and 9a-9b does not form part of the claimed invention.

Referring to Fig. 8a, the starting material is, as mentioned, a billet 200, which is formed of a plurality of adjacent wood lamellae 20a, 20b, each having a longitudinal direction which is substantially parallel with a principal fiber direction of the respective wood lamella, and a generally trapezoidal cross section providing a major base surface bs1, a minor base surface bs2 and a pair of opposing side surfaces ss1, ss2. In the billet, the lamellae are glued together side surface ss1 to side surface ss2, such that major base surfaces bs1 of immediately adjacent lamellae face opposite directions. The major base surfaces bs1 define respective major surfaces of the billet.

Alternatively, the billet 260 as disclosed with respect to Figs 3a-3b may be used.

Referring to Fig. 8b, the billet 200 is sawn up by cuts S4 which are preferably perpendicular to the major surface of the billet and parallel with the longitudinal direction of the lamellae, thus providing a plurality of planks 701 having a width corresponding to a thickness of the billet 200.

Referring to Fig. 8c, after the sawing, the planks 701 may be subjected to a drying step.

Optionally, the planks 701 may then be formatted, such as planed. Referring to Fig. 8d, glue may then be applied to long side edges of the planks by means of a glue applicator 710, after which the planks 701 are glued together long side to long side, such that major surfaces of the planks define a major surface of the board.

At this point, the planks 701 may be subjected to pressing perpendicularly to the longitudinal edges by means of a press 711. That is, the longitudinal edges which are glued together are also pressed together. Optionally, the planks may also be subjected to pressing in a direction perpendicular to the major surfaces.

Referring to Fig. 8e, the board 700 thus formed may be sawn up into panels 702 of a desired shape and size by means of a saw 712.

These panels 702 may then be used, for example in providing panels or boards for use in any of the products (e.g. rib slab, glulam beams, ceiling or floor elements, etc.) discussed above, or as a general board material.

Referring to Fig. 9a, a plurality of such panels 702 may be laminated major surface to major surfaces to form a multi-ply board 703 comprising two, three, or more, layers. Typically, the number of layers may be an uneven number, such as 1, 3, 5, 7 etc. Adjacent panels 702 may be arranged with their principal fiber directions in a non-parallel manner, such as, but not limited to, perpendicular to each other.

Referring to Fig. 9b, the panels 702 thus formed may, alternatively or as a complement, be laminated to a billet 200, 260, such as the one disclosed in Fig. 1h or 3b. For example, a pair of panels 702 may sandwich the billet 200, 260. In such an embodiment, the panels 702 may be arranged with their principal fiber directions being substantially parallel, while the principal fiber direction of the billet 200, 260 may be non-parallel with those of the panels, e.g. perpendicular.

Referring to Figs 10a-10h, which do not form part of the claimed invention, the description will now be directed to a method of making a pillar or beam 820, 830, 840, 850, 860 adapted for receiving a load in its longitudinal, or axial, direction. Such products may potentially be used as columns, pillars, pylons, poles, pipes, tubes or barrels.

Fig. 10a illustrates a billet 200, 260 such as the one disclosed in Fig. 1h or 3b, that is, a billet, which is formed of a plurality of adjacent wood lamellae 20a, 20b, each having a longitudinal direction which is substantially parallel with a principal fiber direction of the respective wood lamella, and a generally trapezoidal cross section providing a major base surface bs1, a minor base surface bs2 and a pair of opposing side surfaces ss1, ss2. In the billet, the lamellae are glued together side surface ss1 to side surface ss2, such that major base surfaces bs1 of immediately adjacent lamellae face opposite directions. The major base surfaces bs1 define respective major surfaces of the billet.

As illustrated in Fig. 10b, the billet 200 may be sawn along a plurality of cuts S6, S7, which are parallel with a principal fiber direction of the lamellae, and which are perpendicular or non-perpendicular to the major surface of the billet, depending on which parts are being formed and for which type of structure. Flence, a plurality of elements 800 are formed, each of which being made up of more than one of the lamellae. The elements 800 may be provided with joint portions to form joinable elements 800’.

As illustrated in Fig. 10c, such joinable elements 800’ may be joined together by joints J6, short end to short end, for example by finger jointing, thus forming an elongate element 810.

As illustrated in Fig. 10d, a plurality of such elongate elements 810 may be connected long side to long side to form a pillar 820. In the example of Fig. 10d, 12 such elongate elements 810 have been joined together by gluing and optionally additional mechanical fasteners.

The structure thus formed presents a polygonal cross section with facetted inner and outer faces.

It is recognized that the structure may be subjected to milling, lathing or grinding to provide a desired final shape thereof, such as circular. Provided that sufficient material thickness is provided, other shapes, such as barrel shapes may be provided, should the structure be used as a column.

Referring to Fig. 10e, there is disclosed an alternative design for providing a 12-sided pillar or column 830. The mutually identical elongate elements 831 from which this pillar or column is made up may be provided either according to the method disclosed in Figs 10a-10c, or according to the method disclosed with reference to Fig. 3a-3b, that is individual lamellae which are joined together end to end, e.g. by finger jointing.

Figs 10f-1 Oh schematically illustrate the freedom of design provided by the present concept.

Thus, tube cross sectional shapes may be provided which are symmetric about e.g. a vertical plane through a centre of gravity of the tube.

As another option, tube cross sectional shapes may be provided which are asymmetric about such a vertical plane.

In Fig. 10f, a 12 sided pillar or column 840 having an approximately rectangular cross section is provided by a combination of elongate elements 831, 810, or by a combination of elongate elements, billets and extended lamellae.

In Fig. 10g, a 12 sided pillar or column 850 having an approximately triangular cross section is provided, also by a combination of elongate elements 831, 200, or by a combination of elongate elements, billets and extended lamellae.

In Fig. 10h, an arched or arcuate structure 860 is provided, also by a combination of elongate elements, or by a combination of elongate elements 861 (formed analogously with the elements 810), billets and extended lamellae.

Such arched structures may be used as ceiling or wall elements and may be formed with any symmetric or asymmetric curvature.

Claims

1. A laminated wood product (260, 260’, 261’, 271, 271’, 280) for use as a construction element, comprising: a plurality of adjacent wood lamellae (20a, 20b), each having a longitudinal direction which is substantially parallel with a principal fiber direction of the respective wood lamella, and a generally trapezoidal cross section providing a major base surface (bs1), a minor base surface (bs2) and a pair of opposing side surfaces (ss1, ss2), wherein the lamellae are glued together side surface (ss1) to side surface (ss2), by a glue suitable for wet gluing, i.e. gluing at a moisture content of the wood lamellae greater than 25 % by dry mass, preferably greater than 30 % by dry mass, and subsequently dried, such that major base surfaces (bs1) of immediately adjacent lamellae face opposite directions, wherein the major base surfaces (bs1) are formed closest to the bark of a log from which the lamella is formed and along a bark side of the log, and a minor base surface (bs2) is formed close to the pith of the log and parallel with the major base surface (bs1), and wherein the major base surfaces (bs1) define respective major surfaces of the wood product, characterized in that a thickness of the wood product, as seen in a direction perpendicular to the major surfaces, is about 6-30 cm, preferably 8-26 cm, and major (bs1) and minor (bs2) base surfaces, which are provided by a pair of immediately adjacent lamellae (20a, 20b, 25a, 25b), and which face the same direction, are situated in spaced apart planes.

2. The laminated wood product as claimed in claim 1, wherein the lamellae present year rings, and wherein year rings at the major base surface (bs1) have a greater bending radius than year rings at the minor base surface (bs2).

3. The laminated wood product as claimed in any one of the preceding claims, wherein an edge portion of the wood product presents means (J3a, J3b, J3c) for mechanically connecting the wood product in at least one direction to another identical wood product.

4. The laminated wood product as claimed in claim 3, wherein said connecting means comprise at least one of: a tongue and/or a groove extending substantially parallel with the base surfaces for providing a mechanical connection in a direction perpendicular to the base surfaces, and locking member extending substantially perpendicular to the base surfaces for providing a mechanical connection in a direction parallel with the base surfaces and perpendicular to the longitudinal direction.

5. The laminated wood product as claimed in any one of claims 1-4, wherein the base surfaces (bs1, bs2) taper along said longitudinal direction.

6. The laminated wood product as claimed in any one of claims 1-4, wherein the base surfaces (bs1, bs2) present a substantially constant width along the longitudinal direction.

7. An elongate laminated wood product, comprising at least two laminated wood products as claimed in any one of the preceding claims, which are joined together in an end-to-end manner, preferably by means of a finger joint (J1, J2, J4).

8. The elongate laminated wood product as claimed in claim 10, comprising at least two pairs of laminated wood products, which are joined together in an end-to-end manner by a respective joint (J4), wherein said joints are offset from each other in the longitudinal direction, preferably by 10-50 % of a length of the laminated wood products.

9. A method of making a laminated wood product for use as a ceiling or floor element having major surfaces and a thickness as seen in a direction perpendicular to the major surfaces, of about 6-30 cm, preferably 8-26 cm, the method comprising: providing a plurality of wood lamellae, each having a longitudinal direction which is substantially parallel with a principal fiber direction of the respective wood lamella, and a generally trapezoidal cross section providing a major base surface (bs1), a minor base surface (bs2) and a pair of opposing side surfaces (ss1, ss2), wherein the major base surfaces (bs1) are formed closest to the bark of a log from which the lamella is formed and along a bark side of the log, and a minor base surface (bs2) is formed close to the pith of the log and parallel with the major base surface (bs1), applying glue suitable for wet gluing to the side surfaces (ss1, ss2) of the wood lamellae (20a, 20b, 25a, 25b), a moisture content of the wood lamellae being greater than 25 % by dry mass, preferably greater than 30 % by dry mass, arranging the wood lamellae side surface (ss1) to side surface (ss2), such that major base surfaces (bs1) of immediately adjacent lamellae face opposite directions and the base surfaces (bs1, bs2) define the respective major surfaces of the wood product, pressing the side surfaces towards each other for a sufficient time to bond the wood lamellae to each other to form a billet (200, 260), characterized by arranging the wood lamellae such that major (bs1) and minor (bs2) base surfaces, which are provided by a pair of immediately adjacent lamellae (20a, 20b, 25a, 25b), and which face the same direction, are situated in spaced apart planes, and subjecting the billet (200, 260) to a drying step subsequent to the bonding.

10. The method as claimed in claim 9, further comprising forming locking means (J3a, J3b) along at least one long side edge of the plank.

11. The method as claimed in any one of claims 9-10, further comprising cutting the thus formed billet along a plane parallel with the longitudinal direction and perpendicular to the major surfaces to form a plank.

12. Use of a laminated wood product as claimed in any one of claims 1-8 as a wall, roof, floor or ceiling element.