WO2001012400A1

WO2001012400A1 - Wooden element for building purposes and a method for the production of such wooden elements

Info

Publication number: WO2001012400A1
Application number: PCT/SE2000/001550
Authority: WO
Inventors: Olle Öberg
Original assignee: Corexor Invest Ab
Priority date: 1999-08-13
Filing date: 2000-08-07
Publication date: 2001-02-22
Also published as: SE514636C2; SE9902893L; AU6602800A; SE9902893D0

Abstract

A wooden element for building purposes comprises two angled flanges. This element consists of a solid piece of wood which is extracted from one and the same log (9), more precisely by means of a pair of first dividing cuts (10, 10'), which extend substantially radially from the area of the centre of the log in order to define external surfaces on the element, as well as a pair of second dividing cuts (12, 12'), which extend from a spot further out from the centre of the log in order to define interior surfaces of the element. In the finished element, the annual rings in the wooden material are so oriented that imaginary tangents to individual annual rings intersect at least the external surfaces on the element in a substantially right angle to the plane of the surfaces, older annual rings being situated closest to a transition portion between the flanges.

Description

WOODEN ELEMENT FOR BUILDING PURPOSES AND A METHOD FOR THE PRODUCTION OF SUCH WOODEN ELEMENTS

Technical Field of the Invention In a first aspect, this invention relates to a wooden element intended for building purposes including two long narrow flanges, which extend at an angle to each other and are defined by a pair of external, plane surfaces which converge in a longitudinal, external transition portion, as well as a pair of interior, plane surfaces which meet in an internal transition portion, the element consisting of a solid piece of wood which is extracted from of one and the same log by means of two pairs of dividing cuts.

Prior Art

In structural engineering, angular wooden elements are found in many different shapes in assembled state. The elements are for instance found as gutters, inner reveals, corner linings, railing lintels, wind and water protection on roof ga- bles, etc. Common for such wooden elements of previously known type is that the same are put together by two individual boards via nails, screws, and/or glue joints. As a consequence of the characteristics, such as fibre orientations, in conventional boards being, in all essentials, uncontrolled, elements of this type are exposed to damage caused by putrefaction at a comparatively early stage. Thus, m the practical production of the elements, boards are used of which the location of extraction n the original log is unknown. In some cases, the individual board may be extracted from the outer sap of the log and in other cases be extracted from the central heartwood. Therefore, the orientation of the annual rings is indefinite. At times, presence of heartwood n the individual board may be oriented inwards and at times outwards in the assembled element. In the traditional sawing of logs, the log is split by means of a plu- rality of parallel sawing cuts. This is something which, m particular at weak logs, may entail that the annual rings of the wood mainly will be located lying m the surface which is turned outwards in the individual boards. By the fact tnat the bulking susceptibility of the wood is larger in the tangential direction (in practice about 7 %) than in the radial direction (about 4 %) paint or other surface treatment layers on the outside of the boards are exposed to large, alternating shrinkage and elongation stresses, which results in crack formations in the protective paint layer as well as in the proper surface wood .

Objects and Features of the Invention

The present invention aims at obviating the above- mentioned inconveniences of previously known wooden elements of the type mentioned and at providing an improved element. Thus, a primary object of the invention is to provide a wooden element formed with two angled flanges with a radically improved rot-resistance. Another object is to create a wooden element, which may be produced in a simple way already in connection with the split of a log into individual pieces of wood in order to avoid any assembling operation in connection with the final assembly in a constructional work. It is also an object to provide a wooden element, which lacks metallic connecting elements that may give rise to rusting or discoloration phenomena in the element. Another object of the invention is to create an angular wooden element, which in a simple and effective way may be connected to additional elements while forming a dense joint between the elements. According to the invention, at least the primary object is attained by the features defined in the characterizing clause of claim 1. Preferred embodiments of the wooden element according to the invention are furthermore defined in the dependent claims 2-5. In a second aspect, the invention also relates to a method for the production of the wooden element in question. The features of this method are seen in claims 6 and 7.

Further Elucidation of Prior Art By WO 97/04205 a wooden element is previously known in the shape of a frame piece for window or door frames, which is extracted from a log by means of radial dividing cut which extend from the area of the centre of the log, imaginary tangents to individual annual rings intersecting the external sur- faces of the frame piece perpendicularly to the plane of the surfaces. However, this element does not have any angled flanges of the type that characterizes the wooden element according to the present invention and may not at all be used in the way, which is intended with the invention.

In WO 98/38019 a method is described for the production of composite wooden products from converted, step-shaped pieces of wood. In this method, the step-shaped pieces of woods are extracted from logs having a diameter of approx. 100 mm. Then, in order to get the desired piece of wood from the log at all, sawing has to take place in such a way that sap is obtained in the thin portion of the piece of wood, while heart- wood is located to the centre area of the wide base part of the piece of wood. In other words, this method of extraction con- flicts with the teaching of the present invention.

In US 4 380 336, an angular element is described which has the similarity to the element according to the invention that the same is extracted in one single piece from one and the same log. However, in this case the angle element con- sists of a roof intended for nesting boxes, which is extracted from the log entirely without considering how the annual rings are oriented in the element. Thus, this nesting box roof is delimited by two pairs of dividing cuts which converge in a "ridge portion", which is located at a considerable distance from the centre of the log. Therefore, the external surfaces of the nesting box roof will have exactly the same disadvantages as the boards of the type initially mentioned, i.e. large and alternating shrinkage and elongation stresses with the ensuing crack formation. This is something that in turn results in dam- age caused by putrefaction in the sap of the surface portions . In SE 9100830-0 (publication number 505 056) a so- called star sawing method is described, according to which board work pieces as well as cross-section-wise triangular pieces of wood are extracted from a log. However, no angular wooden elements of the type that characterizes the present invention may be obtained by means of this method. Brief Description of the Appended Drawings

In the drawings : Fig 1 is a cross-section through a log, from which a wooden element according to the invention is extracted, Fig 2 is a cross-section through a wooden element according to the invention in a first embodiment, Fig 3 is an analogous cross-section showing an alternative embodiment of the element, Fig 4 is a schematic longitudinal view of a wooden element having an axially tapering shape,

Fig 5 is a partial perspective view showing different fields of use for wooden elements according to the invention, Fig 6 is an exploded planar view showing enlarged end portions of two wooden elements which should be spliced, Fig 7 is an end view of one of the wooden elements according to fig 6, Fig 8 is a planar view showing the two elements according to fig 6 in a spliced state, Fig 9 is a planar view corresponding to fig 6 showing an alternative embodiment of wooden elements according to the invention, Fig 10 is an end view of a element according to fig 9, and Fig 11 is a planar view showing the two wooden elements according to fig 9 in a spliced state.

Detailed Description of Preferred Embodiments of the Invention

Each one of the two wooden elements 1, 1' visualised in figs 2 and 3, includes two flanges 2, 3 oriented at an angle to each other, which are delimited by a pair of external, plane surfaces 4, as well as a pair of internal, likewise plane sur^¬ faces 5. The two external surfaces 4 converge into an external transition portion 6, which in the examples shown consists of a sharp corner in the shape of an axial edge line. In practice, the transition portion 6 in the ready-machined element may also have another shape. For instance, the transition portion may consist of a softly rounded surface or, alternatively, a plane- chamfered surface. The two internal surfaces 5 meet in an internal transition portion 7, which in the examples is in the shape of an axial, sharp edge line. Also this transition may be rounded or chamfered in the finished element. The rest of the element is defined by angled, plane edge surfaces 8 at the free edge portions of the flanges 2, 3. In the embodiment according to fig 2, the edge surfaces 8 are oriented perpendicularly to the plane of the flanges. In the embodiment according to fig 3, however, the edge surfaces 8 are oblique in relation to the plane of the flanges, more precisely at an acute angle to the external surfaces . It should also be mentioned that the angle between the flanges 2, 3 in both cases is right, although it is feasible, per se, to form the element so that the flanges extend either at an acute or an obtuse angle to each other.

In fig 1, a log is designated 9 from which elements according to figs 2 and 3 may be extracted. The extraction takes place by applying dividing cuts m a suitable way in the log, e.g. by means of circular saw blades. More precisely, a first pair of dividing cuts 10, 10' are, on one hand, applied for defining the external surfaces 4 of the completed element. These cuts 10, 10' are located at an angle to each other and extend from an area in or near the centre of the log, the mdi- vidual cuts extending approximately radially from the area of the centre of the log. Advantageously, the dividing cuts are achieved by means of circular saw blades 11, 11'. Furthermore, a pair of second dividing cuts 12, 12' are applied, which likewise extend at an angle to each other, although they start from a spot or line which is situated further out from the centre of the log than the spot or line where the dividing cuts 10, 10' meet. These second dividing cuts 12, 12' have the purpose of defining the interior surfaces 5 of the finished element. Also the cuts 12, 12' are achieved by means of circular saw blades 13, 13' .

In practice, the dividing cuts may be achieved in various ways. Thus, it is possible to achieve the cuts m one and the same pass in which the log is axially fed through a stationary sawing station. In doing so, the cuts 12, 12' may be achieved in a first operation while removing the sector-shaped part 14 which exists between said cuts, and then the cuts 10, 10' are applied m a subsequent step while separating a solid, angular work piece which m a suitable way is brought further to final machining. This final machining consists of edging, more precisely by face-machining the free edges of the formed element flanges, preferably by sawing.

When the cutting and edging operations are finished, a solid piece of wood or wooden element is obtained in which the annual rings in the wooden material are so oriented that imaginary tangents to individual annual rings intersect at least the external surfaces 4 at a substantially right angle to the plane of the surfaces, the older annual rings of the wooden material being located closest to the transition portion be- tween the two flanges 2, 3. In the embodiments shown in the drawings, the dividing cuts 10, 12 and 10', 12', respectively, which should define the individual flanges, are located parallel to each other. This means that the flanges are of uniform thickness. In the examples, the two flanges extend at 90° angle to each other. However, it is also feasible to locate the dividing cuts in the log in such a way that the angle between the flanges becomes either acute or obtuse.

In this connection, it should be pointed out that the pair of blades 11, 11' and 13, 13', respectively, which provide the dividing cuts in the log, in a way known per se, should be axially displaced in relation to each other in the sawing station. Preferably, the horizontal blade 11' and 13', respectively, is located up-stream the vertical blade 11 and 13, respectively, with which the same co-operates. In addition, the blades 13, 13' which separate the sector-shaped log part 12 should be located up-stream the blades 11, 11'.

The natural tree trunks from which logs with suitable lengths are taken out, are always more or less cone-shaped, i.e. they taper from the root end of the trunk towards the top end. In fig 4 is shown how markedly cone-shaped logs may be used in order to achieve finished wooden elements with a tapering shape. In such logs, the two dividing cuts 10, 10' which should form the external surfaces of the element are located in such a manner that the crossing or meeting line of the cuts ex- tends parallel to the centre of the log line. Advantageously, the crossing line may be located in, or very near, the centre line of the log. After this, the edging of the flanges is car^¬ ried out by means of sawing cuts which in the main follow the envelope surface of the log, i.e. the edging cuts are located substantially parallel to the envelope surface. By the fact that the log is cone-shaped, the two flanges will therefore taper from a thick end shown to the right in fig 4 towards a more slender end shown to the left. Elements produced according to fig 4 are especially suitable for use as gutters. Thus, gutters having a natural tapering shape of this type may be mounted in an aesthetically attractive way by the fact that the two free, upper edges of the gutter are located parallel to appurtenant eaves at the same time as the requisite fall is obtained by the fact that the transition portion serving as a bottom extends at a certain angle in relation to the upper edges.

A primary advantage of the wooden element according to the invention is that the annual rings in the wooden material of the element extend the main perpendicularly to the external and interior surfaces, which define the element.

Therefore, since the bulking tendency of the wood in the tangential direction is minimal, the tendency for crack formation in the surface wood is minimal . This means turn that the crack formation tendencies in an external, protective colour or surface treatment layer are reduced to a minimum. Furthermore, the part of the element that is exposed to the effect of water or precipitation, viz . the transition portion between the flanges, emanates from the heartwood zone of the log, which is rich not only on resin, but also on pinosylvin in such varie- ties of trees where these are included. This means that the transition portion in a natural way resists attack of mould fungus and has a minimal tendency to suck water. Another advantage is that the element consists of a genuine piece of wood with no joints or metallic connecting elements, respectively, such as nails or screws. In this way, the risk of discoloration by virtue of rusting metal is eliminated. In addition, the unbroken transition portion between the flanges becomes stronger than a joint held together by, for instance, nails or screws between two conventional boards. Reference is now made to fig 5, which illustrates different application possibilities for the wooden element according to the invention. Thus, fig 5, a gutter is desig^¬ nated la, which advantageously may be made according to fig 4, i.e. with a tapering shape, lb designates an element forming a combined wind and water protection board adjacent to the gable on a roof, lc illustrates how the element may be used as a corner lining, and Id showing how the element may be used as an inner reveal. Of course, the element may also be used as an architrave, le designates an element, which is used as a lintel to a railing. Furthermore, it should be mentioned that two or more elements of the kind according to the invention may be united with each other while forming other products. For instance, two elements may be united with the free edges of the flanges connected in pairs while forming a tubular product. In this connection, the joint between the elements may consist of glue joints. In the embodiment according to fig 3, the plane and chamfered edge surfaces 8 may be glued together along diagonal joint surfaces at diametrically opposed corners. Tubes produced in this way may, in practice, be used to cover other tubes, e.g. metallic tubes, or cables. They may also be used as rainwater pipes, preferably in connection with gutters of the previously mentioned type. Also, two elements according to the invention may be united to each other while forming a support- ing, hollow pillar or post. If two elements according to fig 4 are put together in the above described way, a tapering tube product is formed.

Reference is now made to figs 6-8, which show how the angular wooden element according to the invention may be given an end shape specially suitable for joining. In practice, the element should be given this end shape at each one of the two opposite ends thereof, although it is feasible, per se, to make only one of the ends with the end shape in question. The end shape shown is defined by at least three recesses 15, 16, 17 and equally many male members 18, 19, 20 having the same shape and dimensions as the recesses. In fig 7, at A, an imaginary central plane is shown which intersects the wooden element in the aforementioned two transition portions 6, 7 and forms a bisector in relation to the two flanges 2, 3 (i.e. the flanges 2, 3 extend at equally large, acute angles to the central plane A) . Two of said recesses, viz . recesses 15 and 16, and the male member 18 positioned therebetween, are located on one side of said central plane A, while the two male members 19 and 20 and the recess 17 positioned therebetween are located on the other side of the central plane A. Therefore, when joining two elements 1, 1' having identically the same end shape, the elements may be mirror-inverted so that the male members on one side of the element will engage the corresponding recesses in the other element.

In the shown, preferred embodiment, two of the male members, viz . the male members 18 and 19 are wedge-shaped, while the third male member 20 is of uniform width. The recess 15 is delimited by an edge surface 21 which extends perpendicu- larly to the axial extension of the wooden element, as well as an edge surface 22 which extends parallel to the longitudinal axis of the wooden element. In addition to this axial edge surface 22, the male member 18 is delimited by an oblique edge surface 23, which extends from the outermost tip of the male member to the central plane A. In an analogous way, the male member 19 is delimited by an axial edge surface 24 (which is situated in the central plane A) and an oblique edge surface

25. The male member 20 is delimited by an axial edge surface

26, as well as an outer edge surface 27, which extends perpen- dicularly to the longitudinal axis of the wooden element. All male members 18, 19, 20 are equally long, the width of the male member 20 corresponding to the width of the recess 15, and the wedge-shaped male members 18, 19 having the same shape and size as the recesses 16, 17. In the shown, preferred embodiment, all delimiting edge surfaces 21, 22, 23, 24, 25, 26 and 27 extend in a plane directed perpendicularly to the plane of the drawing. In this way, the practical design of the ends of the wooden element is facilitated inasmuch as a sawing tool (e.g. a milling cutter) may be brought to pass the end portion of the wooden element in a single pass.

In fig 8, the two wooden elements 1, 1' are shown in a spliced or joined state. As may be clearly seen in this figure, all male members fit exactly into the corresponding re- cesses. Furthermore, it is visualised how screws 28 may be drawn obliquely into the two outer male members 20, as well as from the outside at the corner transition in such a way that at least one screw pulls together two edge surfaces 24 abutting against each other. In figs 9-11, an alternative embodiment is illustrated according to which the male member 19 is only partially wedge-shaped. In this case, a transverse edge surface 29 has been formed which extends perpendicularly to the longitudinal axis of the wooden element between the male member 19 and the recess 16. In this way, the existence of an axial splicing zone exactly in the corner transition between the two flanges of the elements is eliminated, as is the case in the embodiment according to figs 6-8. Therefore, the embodiment according to figs 9-11 is especially suited for use in gutters in which water flows along the internal corner transition between the flanges serving as a bottom.

Instead of entirely or partly wedge-shaped male members and recesses, respectively, there may also be male members and recesses, respectively, with another shape, e.g. trapezoid and rectangular, respectively.

Claims

Cl a ims

1. Wooden element for building purposes, including two long narrow flanges (2,3), which extend at an angle to each other and are defined by a pair of external, plane surfaces (4) which converge in a longitudinal, external transition portion (6), as well as a pair of internal, plane surfaces (5) which meet in an internal transition portion, the element consisting of a solid piece of wood (1) which is extracted from of one and the same log (9) by means of two pairs of dividing cuts (10, 10', 12,

12'), c h a r a c t e r i z e d in that a pair of first dividing cuts (10, 10') extend substantially radially from the area of the centre of the log in order to define the external surfaces (4) of the element, while a pair of second dividing cuts (12, 12') extend from a spot further out from the centre of the log in order to define the internal surfaces (5) of the element, the annual rings in the wooden material being so oriented that imaginary tangents to individual annual rings intersect at least the external surfaces (4) in a substantially right angle to the plane of the surfaces, and older annual rings being situated closest to said external transition portion (6) .

2. Wooden element according to claim 1, c h a r a c t e ri z e d in that the two flanges (2, 3) taper off from a thick end of the element towards a narrow end at an angle α which is dependent on the natural conicity of the log.

3. Wooden element according to claim 1, c h a r a c t e ri z e d in that at least one of the two opposite ends of the element is formed with a shape suitable for joining, which is defined by at least three recesses (15, 16, 17) and equally many male members (18, 19, 20) with the same shape and dimensions in pairs as the recesses, two recesses (15, 16) and a male member (18) therebetween being positioned on one side of an imaginary central plane (A) which intersects said transition portions (6, 7), at the same time as two male members (19, 20) and a recess (17) positioned therebetween being located on the other side of the central plane (A) so that the male members of a first element (1) should engage analogous, opposite recesses of a second element (1') which is spliced with the first one.

4. Wooden element according to claim 3, c h a r a c t e r- i z e d in that two male members (18, 19) which define an intermediate recess (16) are at least partially wedge-shaped, while a third male member, which extends along the outer edge of one of the flanges (3), is of uniform width.

5. Wooden element according to claim 3 or 4, c h a r a ct e r i z e d in that edge surfaces (22, 24, 26) which define said male member (18, 19, 20) are parallel to said central plane (A) .

6. Method for the production of wooden elements intended for building purposes of the type that comprises two long narrow flanges (2, 3), which extend at an angle to each other and are defined by a pair of external, plane surfaces (4) which converge in a longitudinal, external transition portion (6), as well as a pair of interior, plane surfaces (5) which meet in an internal transition portion (7), two pairs of dividing cuts (10, 10', 12, 12') being applied in one and the same log (9) in order to form said surfaces and define said flanges, c h a r- a c t e r i z e d in that a pair of first dividing cuts (10, 10') are applied in the log, which extend substantially radially and at an angle to each other from the area of the centre of the log in order to define the external surfaces (4) of the element, as well as a pair of second dividing cuts (12, 12'), which extend at an angle to each other from a spot further out from the centre of the log in order to define the interior surfaces (5) of the element, while forming a solid piece of wood in which the annual rings in the wooden material are so ori^¬ ented that imaginary tangents to individual annual rings inter^¬ sect at least the external surfaces (4) at a substantially right angle to the plane of the surfaces, and older annual rings being located closest to said external transition portion (6) .

7. Method according to claim 6, c h a r a c t e r i z e d in that the two first dividing cuts (10, 10') are brought to meet each other along a line which is parallel to the centre of the log and that edge surfaces (8) on the two flanges (2, 3) are located substantially parallel to the envelope surface of a cone-shaped log while achieving an element in which the two flanges taper off from a thick end towards a narrow end.