A METHOD FOR DIVIDING A LOG AND FOR PRODUCING A COMPOSED WOOD UNIT

Abstract: In a method for producing a wood unit composed by a plurality of wood pieces glued to each other it is started from at least one elongated wood piece (1) having a substantially rectangular cross section on which cuts (2, 3, 4, 5) are applied for obtaining a wood piece for said wood unit. Said cuts are applied in the longitudinal direction of the starting wood piece substantially in parallel with a diagonal plane extending from one (6) to another (7) corner of the rectangle forming the cross section of the starting wood piece, and a plurality of wood pieces resulting from such cuts are glued to each other by placing longitudinal surfaces thereof against each other for obtaining a composed wood unit.

Description: A method for dividing a log and for producing a composed wood unit FIELD OF THE INVENTION AND PRIOR ART The present invention relates to a method for dividing a log ac- cording to the preamble of the appended patent claim 1 as well as a method for producing a wood unit composed by a plurality of wood pieces glued to each other, in which it is started from at least an elongated wood piece having a substantially rectangu¬ lar cross-section, on which cuts are applied for obtaining a wood piece for said wood unit. "Rectangular cross-section" is defined as a cross-section hav¬ ing four right-angled corners and does accordingly also com¬ prise a square cross-section. A number of different techniques for dividing a log are known, and it is usually proceeded in the way that a number of cuts parallel to each other are applied in the longitudinal direction of the log for gaining planks and boards from the log with a possi- ble intermediate treatment in an edging machine and/or planing machine. Raw unrefined products of a comparatively low quality is then obtained, which after drying are delivered to the con¬ sumers, of which a part is manufacturer of refined wood prod¬ ucts, such as for example glued-joint sheets, pieces of furniture and the like. Thus, the log is in a first line divided without ob¬ taining any degree of refinement of the products obtained. Fur¬ thermore, the main part of the surface near wood will normally get lost with respect to the possibilities to use it for forming wood products of high quality and this wood is cut into chips. The same is valid for thinner log parts, which with the conven- tional dividing technique only give rise to products of such a low quality that cutting thereof into chips is often the only realistic alternative. SUMMARY OF THE INVENTION The object of the present invention is to provide a method for dividing a log of the type defined in the introduction, which makes it possible to find a remedy to the inconveniences men- tioned above of the log dividing methods according to the prior art and especially makes it possible to in a better way utilise the wood of the log and makes it possible to produce wood products having improved quality properties, as well as provid¬ ing a method for producing wood units composed by a plurality of wood pieces glued to each other according to the preamble of the appended independent patent claim therefor, through which glued wood products with improved quality properties may be produced in both a simple and by that labour saving and material saving way. These objects are according to the invention obtained by pro¬ viding the methods according to the appended independent patent claims. By dividing the log in a second step in a plurality of second wood pieces by applying cuts in the longitudinal direction of the first wood piece having a substantially rectangular cross-sec¬ tion substantially in parallel with a diagonal plane extending from one corner to another of a rectangle forming the cross- section of the first wood piece, second wood pieces, which may easily be glued to each other, by the fact that they have glue surfaces that matches when they are brought together, in a number of combinations for obtaining glued wood products having good quality properties, are obtained in a very simple way. Besides the fact that the second wood pieces resulting in this way have such cross-section shapes that they may easily be combined for obtaining numerous wood products the inven- tional way of applying the cuts means that these products may get very good properties by the fact that they will have a ten- dency to automatically have annual rings standing with respect to several surfaces thereof, so that these surfaces will be very wear resistant. Thanks to the possibility to in this way remarkably raise the quality of the wood products that may follow upon said dividing method, a greater part of the surface near wood and thin logs may through the invention be saved from the chips cutter and instead be used for producing wood products for which a con¬ siderably higher prize is set. By the fact that in the method according to the invention for pro¬ ducing the wood unit composed by a plurality of wood pieces glued to each other the cuts are applied in the longitudinal di¬ rection of the starting wood piece substantially in parallel with a diagonal plane extending between one corner and another cor¬ ner of the rectangle forming the cross-section of the starting wood piece and a plurality of wood pieces resulting from such cuts are glued to each other by applying longitudinal surfaces thereof against each other for obtaining a composed wood unit, glued wood products having very good quality properties may be produced through very simple means, i.e. in a labour or work saving way, while at the same time utilising the material of the starting wood piece. The invention comprises also that wood pieces resulting from such cuts, which are glued to each other derive from different starting wood pieces. Thus, it will according to the invention be possible to in one single line achieve division and direct production of refined glued wood products having good quality properties, although the invention also comprises the possibility to glue the wood pieces resulting from said cuts applied substantially in parallel with said diagonal plane to each other far later, maybe in an¬ other place. According to a preferred embodiment of the method for produc¬ ing a composed wood unit the starting wood piece is before the application of said cuts put with said diagonal plane substan¬ tially vertically arranged, and the starting wood piece is kept in this position during the application of said cuts. The wood pieces to be glued to each other thereafter for obtaining a wood unit in the form of a glued high quality wood product may in this way be produced while using simple means through a conven¬ tional cutting equipment without any special demands on saw blades being obliquely positioned or the like. The invention is applicable to starting wood pieces having sides extending parallel to the fibres as well as to the centre or core, said cuts being substantially parallel to said diagonal plane then being applied substantially in parallel with the fibre direc- tion and the center axis of the starting wood piece, respectively. All the wood pieces resulting from said cuts are then getting glue surfaces matching and brought together and which may be glued to each other for obtaining wood units in the form of high quality glued wood product, in which the wood pieces resulting from the cuts applied farthest away from said diagonal plane and having a cross-section of a right angled triangle as well as the wood pieces resulting from the cuts applied closer to said diagonal plane, which have four or six corners (when they are formed by two cuts located on both sides of said diagonal plane), makes it possible to obtain such high quality glued wood products without any requirement of any further dividing or ma¬ terial removal before gluing. Thus, a further preferred embodiment of the invention relates to a method in which two substantially equal wood pieces obtained by applying said cuts and having the cross-section shape of a right angled triangle with the hypotenuse formed by a said cut are glued to each other with the surface of the respective wood piece resulting from the respective cut as glue surface while forming a wood unit having a substantially rectangular cross- section. Surface near wood may in this way be utilised for ob¬ taining a glued wood product having a high quality, which in that case will have annular rings standing towards the surfaces thereof. According to a further preferred embodiment of the invention two of said cuts are applied on the same side of said diagonal plane so that a wood piece having a substantially trapezoidal cross-section is obtained, whereupon four wood pieces so ob¬ tained are glued to each other with the opposite surfaces of the respective wood piece extending obliquely with respect to each other as gluing surfaces with the parallel sides of the respective wood piece orientated substantially perpendicularly to corre¬ sponding sides of an adjacent wood piece while forming a wood unit having a substantially rectangular outer cross-section and an inner longitudinal hollow space having a substantial rectangular cross-section. A high quality wood unit having a very large outer cross-section with respect to the cross-section with respect to the wood pieces being parts thereof may be obtained in this way, and said wood unit will also have wear resistant surfaces thanks to the annular rings standing there- against. Further advantages as well as advantageous features of the in¬ vention appear from the other dependent patent claims as well as the following description. BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, below follows a de¬ scription of preferred embodiments of the invention cited as ex- amples. In the drawings: Fig. 1 shows schematically how different cuts are applied on a starting wood piece in a method according to a pre¬ ferred embodiment of the invention, Fig. 2 shows a cross-section of a wood unit produced by a method according to the invention, Fig. 3 is a perspective view of a wood unit produced by glu¬ ing a plurality of wood units according to Fig. 2 to each other, Fig. 4 is a wood unit produced according to a method accord¬ ing to the invention, Fig. 5 illustrates schematically how wood pieces resulting from the division according to the invention may be glued to each other to form wood units, Fig. 6 shows a cross-section of a wood unit produced through a method according to the invention, Fig. 7 shows a cross-section of a wood unit produced ac¬ cording to a further method according to the invention, Fig. 8 illustrates schematically how a wood piece obtained by the division shown in Fig. 1 may be divided further into two pieces which may be glued to each other for obtaining a wood unit, Fig. 9 is a view corresponding to Fig. 1 with cuts applied on a rectangular starting wood piece having adjacent sides of different lengths, and Fig. 10 is a cross-section of a wood unit produced through a method according to the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION It is illustrated in Fig. 1 how according to a preferred embodi- ment of the invention a log, which has been divided for obtain¬ ing a starting wood piece 1 having a substantially square cross- section and with the center of the log extending substantially through the center of the square forming the cross-section of the starting wood piece, may be cut by applying different cuts 2, 3, 4, 5 substantially in parallel with a diagonal plane extending from one corner 6 to another corner 7 of said square. A starting wood piece 1 is then preferably put with said diagonal extend¬ ing vertically when the cuts 2-5 are applied, so that conven¬ tional cutting equipment may easily be utilised, without any re- quirement of obliquely orientated saw blades or the like. It is emphasised that the invention comprises the application of such cuts at any distances from said diagonal plane and in any num¬ ber for one and the same starting wood piece 1. The wood pieces 8-12 resulting in this way from the application of the cuts 2, 3, 4 and 5 may be glued to other wood pieces obtained in a similar way, which may be obtained from one or several other starting wood pieces or from the same starting wood piece 1. Some different possibilities to obtain high quality wood units from wood pieces so obtained will be shown in the following figures, but these are not in any way exhausting for the inven¬ tion. It is illustrated in Fig. 2 how two wood pieces 8, 12 obtained through cuts 2, 5 applied on a starting wood piece farthest away from said diagonal plane may be glued to each other with a surface resulting from a respective cut against the respective wood piece as glue surface while forming a wood unit 13 having a substantially rectangular, in this case a square cross-section, since the starting wood piece has a square cross-section. This wood unit will command a comparatively high price, in particu¬ lar when having in mind that it may be obtained entirely from surface near wood, since it will be resistant to wear with the annual rings standing towards all surfaces. It is illustrated in Fig. 3 how a plurality of wood units 13 may be put side by side and glued together for obtaining a composed glued wood product 26 in the form of a glued-joint sheet having a longitudinal substantially rectangular cross-section. Another wood unit 14, which may be produced by gluing wood pieces of the same type as the wood piece 9 and 11 in Fig. 1 , is shown in Fig. 4. Thus, it is obtained by applying two such cuts on the same side of said diagonal plane, so that a wood piece 9 having a substantial trapezoidal cross-section is obtained, whereupon four wood pieces so obtained are glued to each other with the opposite surfaces 15 of the respective wood piece extending obliquely with respect to each other as gluing surfaces with the parallel sides of the respective wood piece substantially perpendicularly orientated with respect to the cor¬ responding sides of the adjacent wood pieces. A wood unit having a substantially square outer cross-section with an inner longitudinal hollow space 16 having a substantially square cross-section is formed in this way. This wood unit has also an- nual rings standing substantially towards the outer surfaces thereof and in addition thereto a high quality glued wood prod¬ uct having a comparatively large outer cross-section may be obtained from comparatively little material. A further example of how wood pieces 9 of the type included in the wood unit according to Fig. 4 may be glued to each other for obtaining high quality glued wood products is shown in Fig. 5. Thus, it is possible to turn the corresponding of the parallel surfaces of two equal such wood pieces 9 towards each other and to glue such a couple of wood pieces 9 to the couple hav¬ ing the opposite surfaces turned towards each other in the way shown in Fig. 5. This may be repeated a desired number of times by alternating the directions of the surface pieces in this way for obtaining a glued wood unit having annual rings stand- ing substantially towards large surfaces thereof. It is illustrated in Fig. 6 how it is possible to obtain a composed wood unit 18 by gluing wood pieces of the same type as the wood pieces 1 and 12 in Fig. 1 to each other, so that a wood unit having a longitudinal rectangular cross-section is obtained, which has annual rings standing towards the large sides 19 thereof. Thus, two such wood pieces 11 having a substantial trapezoidal cross-section are glued to each other with the short and parallel sides against each other, wherein a wood piece 12 having a cross-section of a right angled triangle is glued into the respective V-shaped slot so formed, so that the hypotenuse of the respective cross-section triangle will form one side of said elongated rectangular cross-section. It is pointed out that it when it is stated that such a wood piece having a substantially trapezoidal cross-section is obtained by applying two cuts on the same side of said diagonal plane, this also comprises that one of the cuts is applied according to said diagonal plane. It is illustrated in Fig. 7 how a wood unit 20 having an octagonal cross-section may be obtained by gluing wood pieces of the same type as the wood piece 10 in Fig. 1 to each other, i.e. by gluing wood pieces obtained by applying cuts on both sides of said diagonal plane, which have an hexagonal cross-section, to each other with a surface 22 adjacent to the respective right angled corner 21 as gluing surface of each wood piece against adjacent wood pieces and with the parallel sides of the respec¬ tive wood piece substantially perpendicularly directed towards the corresponding sides of the adjacent wood pieces while forming a wood unit having an octagonal outer cross-section with an inner elongated hollow space 23 having a substantially square cross-section. This wood unit will have the same advan¬ tages with respect to "cross-section gain" and wear resistance in the form of annual rings standing towards the outer surfaces thereof as the wood unit illustrated in Fig. 4. It is illustrated in Fig. 8 how a wood piece obtained in the way according to the invention having a substantially trapezoidal cross-section may be divided further by applying cuts 24 sub¬ stantially perpendicularly to the two parallel sides, whereupon for one of the wood pieces so obtained end is shifted for end and these are then glued together to each other for obtaining a wood unit 25 having a substantially rectangular cross-section and annual rings standing towards the surfaces thereof. It is illustrated in Figs. 9 and 10 how the method according to the invention may be applied to a starting wood piece having a rectangular cross-section with adjacent sides of different lengths by applying the three cuts 26-28 substantial in parallel with a diagonal (corresponding to the cut 26) of a cross-section rectangle and gluing the wood pieces 29-32 so resulted to the wood unit 34 according to Fig. 10. This will, besides the fact that it has annual rings standing towards the large sides thereof, have an inner elongated hollow space 33 having a parallelogram-shaped cross-section, which means an increase of the area inscribed by the outer contour of the cross-section. Thus, through the dividing or disintegrating method according to the invention dividing according to cuts in parallel with said di¬ agonal plane and gluing wood pieces so obtained to each other is realised in one single production line for obtaining a glued wood product having a remarkable degree of refinement already in connection with the division of a log. This may primarily be obtained by the fact that the wood pieces resulting from the di¬ vision according to the invention have such shapes that they are easy to glue to each other while being pressed against each other. The strong raise of quality of the glued wood products is furthermore ensured by the special orientation that these sur- faces will get with respect to the respective annual rings. It is emphasised that the methods according to the invention comprises fibre parallel as well as center parallel cutting, so that the definition "cuts are applied in the longitudinal direction of the starting wood piece substantially in parallel with a diago¬ nal plane" in the patent claims also comprises such fibre paral¬ lel cutting, in which said cuts extend along lines being in paral¬ lel with a diagonal line running from one corner to another in each cross-section plane, although the surfaces formed in real- ity by the cutting will not be completely parallel to said diagonal plane. The invention is of course not in any way restricted to the pre¬ ferred embodiments described above, but several possibilities to modifications thereof would be apparent to a man skilled in the art without departing from the basic idea of the invention.

Claims: Claims 1. A method for dividing a log comprising a first step of applying two couples of cuts in the longitudinal direction of the log, the cuts belonging to the same couple being separated and extend¬ ing substantially in parallel with each other with respect to their extension in the cross-section of the log and substantially per¬ pendicularly to the cuts belonging to the other couple for obtain¬ ing an elongated first wood piece (1) having a substantially rectangular cross-section, characterized in that the division comprises a second step in which said first wood piece is di¬ vided into a plurality of second wood pieces (8-12, 29-32) by applying cuts (2-5, 26-28) thereon in the longitudinal direction thereof substantially in parallel with a diagonal plane extending from one corner (6) to another (7) of the rectangle forming the cross-section of the first wood piece. 2. A method according to claim 1 , characterized in that said cuts belonging to one and the same couple are applied at sub- stantially the same distance from the center of the log. 3. A method for producing a wood unit composed by a plurality of wood pieces glued to each other, in which it is started form at least one elongated wood piece (1) having a substantially rec- tangular cross-section, on which cuts (2-5, 26-28) are applied for obtaining wood pieces (8-12, 29-32) for said wood unit, characterized in that said cuts are applied in the longitudinal di¬ rection of the starting wood piece substantially in parallel with a diagonal plane extending from one corner (6) to another (7) of the rectangle forming the cross-section of the starting wood piece, and a plurality of wood pieces resulting from such cuts are glued to each other by applying longitudinal surfaces thereof against each other for obtaining a composed wood unit (13, 14, 17, 18, 20, 25, 26, 34). 4. A method according to claim 3, characterized in that said cuts (2-5, 26-28) are applied on a wood piece (1) forming the center yield of a log with the center located substantially in the middle of said cross-section rectangle. 5. A method according to claim 3 or 4, characterized in that the starting wood piece (1) is put with said diagonal plane arranged substantially vertically, and that the starting wood piece is kept in this position during the application of said cuts. 6. A method according to claim 4 or 5, characterized in that it is started from at least an elongated wood piece (1) having a substantially rectangular cross-section tapering in the longitudi¬ nal direction of said piece from one end to the other thereof with the longitudinal sides extending substantially in parallel with the fibre direction of said piece, and that said cuts (2-5, 26-28) are applied substantially in parallel with said fibre direction. 7. A method according to claim 4 or 5, characterized in that it is started from at least one elongated wood piece (1) having a substantially rectangular cross-section being substantially un¬ changed along the longitudinal direction of said piece, and that said cuts (2-5, 26-28) are applied substantially in parallel with the central axis of said piece. 8. A method according to any of claims 3-7, characterized in that two substantially equal wood pieces (8, 12) obtained through the application of said cuts (2, 5) and having a cross- section shape of a right angled triangle with the hypotenuse formed by one said cut (2, 5) are glued to each other with the surface of the respective wood piece resulting from the respec¬ tive cut as gluing surface while forming a wood unit (13) having a substantially rectangular cross-section. 9. A method according to claim 8, characterized in that a plural¬ ity of wood units (13) so obtained are laid next to each other and are glued together while forming a composed sheet-like wood unit (26) having a cross-section of an elongated rectan- gle. 10. A method according to any of claims 3-7, characterized in that two of said cuts (2, 3 or 4, 5) are applied on the same side of said diagonal plane, so that a wood piece (9, 1 1) having a substantially trapezoidal cross-section is obtained, and that four wood pieces so obtained are glued to each other with the op¬ posite surfaces (15) of the respective wood piece extending obliquely with respect to each other as gluing surfaces with the parallel sides of the respective wood piece orientated substan- tially perpendicularly to corresponding sides of an adjacent wood piece while forming a wood unit (14) having a substan¬ tially rectangular outer cross-section and an inner longitudinal hollow space (16) having a substantial rectangular cross-sec¬ tion. 11. A method according to any of claims 3-7, characterized in that one of said cuts (3, 4) is applied from both sides of said di¬ agonal plane while obtaining a wood piece (10) having a hex¬ agonal cross-section, and that four substantially equal such wood pieces are glued to each other with the surface (22) close to the respective right angled corners as gluing surface of each wood piece against adjacent wood pieces and with the parallel sides of the respective wood piece orientated substantially per¬ pendicularly to the corresponding sides of the adjacent wood piece while forming a wood unit (20) having an octagonal outer cross-section with an inner longitudinal hollow space (23) hav¬ ing a substantially rectangular cross-section.

Inventors: HAMMARSTROEM LARS, HAMMARSTROEM, LARS
Applicants: HAMMARSTROEM LARS, HAMMARSTROEM, LARS
Application year: 1996
Main classification: B27B1
IPC codes: B27B1, B27M3, E04C3