AU623344B2 - Method of sawing timber and timber products formed thereby - Google Patents

Description

COMMONWEALTH OF AUSTRAL PATENTS ACT 1952-69 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: P15452, PI 5645 PJ 1035 16.11.1987, 27.,1.1987 19.10.1988 Complete Specification Lodged: Accepid: Published: Priority: 00 0 0 0 0 Related Art 0 0 0C' 0 0 Name of Applicant: ANDREW KARL IKNORR ,,Address of Applicantt 2Actual Inventor: Address for Service: RIVB 1515, Bolgers Road, Devon North, Victoria, Australia ANDREW KARL KNORR EDWD. WATERS SONS, 50 QUEEN STREET, MELBOURNE,, AUC)TRALIA, 3000.

0CC 0~ Complete Specification for the Invention entitled: METHOD OF SAWING TIMBIER AND TIMBER 'CRODUCTS FORMED THEREBY The following statement is a full description of this Invention, including the best method of performing it known to me

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0 2 METHOD OF SAWING TIMBER AND TIMBER PRODUCTS FORMED THEREBY The present invention relates to improved methods of milling timber and to improved timber products formed therefrom.

Conventionally, timber planks or other similar products are produced by longitudinally sawing a log in a desired pattern. Generally, planks that are quartersawn, that is with the major faces extending generally across the growth rings of the log (as opposed to generally parallel to the growth rings), provides a higher quality product.

Quatersawn planks generally exhibit less lateral warping, provides a hard wearing surface with least movement across its quartersawn face, and with many species provides a more attractive appearance on the major faces. The difficulty is that if all planks formed from a log are quartersawn, there is necessarily a very high wastage of timber from any particular log. It is therefore more common to use a combination of backsawing and quartersawing to utilise the log more fully, however, even using these techniques there 20 can be up to fifty percent wastage from any particular log.

The foregoing difficulties can be aggravated by logs having specific faults, for example the centre is often formed from weak or faulty wood and needs to be excluded.

Accordingly ,-e-hes-e-t invention has for its objective the provision of a method of forming timber products from a log that enables a better utilisati of the available wood in the log. The present invent n also aims at providing an improved timber product p duced by the basic methods of the invention.

Accordingly, the presen invention provides a 30 method of forming a timber oduct from a log, said method comprising sawing said og along longitudinally extending and radially extee ng lines to form said timber product being substa ally elongated wedge shaped elements.

Convenie ty, the longitudinally extending and radially ext ning lines extend from a peripheral surface of said log '-te-s-id log to a position les thhln---e- -al to half he-- .I1 The present invention aims at providing an improved method of sawing a log into wedge shaped elements so that improved laminated timber products can be formed therefrom. The invention also anticipates the provision of apparatus to achieve the aforesaid sawing method and also the provision of certain timber products formed thereby.

Accordingly the present invention provides a method of sawing a complete log to produce elongated wedge shaped elements the said method comprising the steps of: mounting said complete log (16) for rotation about a central longitudinal axis extending through said log (16); arranging cutting means (20, 21, 54) adjacent said log and creating a radial cut (17) in said log extending to a predetermined depth so that in combination with subsequent cuts an uncut portion of the log at an apex of two radial faces is left a o attached to an uncut central core of a log or so that the apex of the radial faces is a° just severed from parts of said log adjacent said central longitudinal axis but S 1 5 essentially remain in position with the remainder of said log; a~a establishing relative movement between said cutting means and said log whereby °i said radial cut is extended longitudinally along said log (16); a withdrawing said cutting means from said log (16) and rotating said log (16) through a predetermined angle; operating said cutting means to form a further radial longitudinally extending cut o (17); a repeating steps and until a plurality of and the desired number of said radial longitudinally extenai~g cuts are formed in said log, o" I i

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0 0P 0 4 00o D00 0 0 00 04 3 -d+m-aeter of said log and said log is subjected to adryi or treatment step prior to separation into ind' t said elongated wedge shaped elements. econd embodiment the elongated wedge shaped erents may be separated from the 5 log during_-a ng along said longitudinally extending and r a-e-x-te-nding lines.

In accordance with a further embodiment, two or more individually formed elongated wedge shaped elements are laminated together in a manner such that growth rings of the wood forming each said element are substantially parallel to each other in all said elements laminated. Conveniently, the timber product is formed by at least two said individual elongated wedge shaped elements such that an apex of one said element is located adjacent a wider end zone of the other said element and vice versa. In an alternative embodiment the timber product is formed by two said elongated wedge elements each having two side surfaces angled with respect to each other defining an acute angle therebetween and an end surface joining said side surfaces 20 at a wider portion of the element, said two elongated wedge shape elements being laminated by joining the respective end surfaces together such that one said side surface on one of said elements is substantially parallel to a said side surface on the other of said elements.

25 According to a further aspect of the present invention, a timber product is provided comprising an elongated wedge shaped element having longitudinally extending side faces forming an acute angle with each other, said side faces being formed by sawing a log along radial 30 and longitudinally extending saw cuts to form said side faces whereby growth rings of wood forming said element are arranged substantially perpendicular to said side faces.

What is intended by the use of "perpendicular" in this context is perpendicular if the growth rings in a log were perfectly circular bearing in mind, in practice, timber is a natural product subject to some imperfections. Where expressions such as "perpendicular to", "parallel to" and 00 0 0 0I 0 00 0 4 0 4, L~L~-L~L~L~L~L~L~L~L~L1Y -1 I_ 4 "tangent to" in relation to the growth rings are used herein including the accompanying claims, such expressions should be interpreted bearing in mind that timber is a natural product subject to many variations and imperfections in practice.

In accordance with a preferred embodiment at least two of the aforesaid elements are laminated to one another such that the growth rings of each said element are substantially parallel to the growth rings of all other said elements. Conveniently, the elements may be laminated to one another with respective said side faces of adjacent said elements engaging one another and with a thinner portion of each said element being located adjacent a thicker portion of an adjacent said element. In another embodiment each aid element may include an end face forming said side faces and a pair of said elements are laminated together by o joining respective said end faces together such that one L O said side face of one said element is parallel to a said side surface of the other said element. Conveniently, the 0 0 o 20 end faces may be offset relative to one another. Moreover, 0 3, 20 it is possible to arrange for the elements forming such a 00 Scomposite product to be formed of different timber species.

The laminating of the elements may be formed by gluing, nailing (or other mechanical fasteners) or a combination of gluing and nailing (or other mechanical fasteners).

00 The advantages achieved by the performance of the present invention, or preferred aspects thereof, are o numerous. The log sawing method produces wedge shaped elements with major side surfaces that are always perfectly quartersawn. The method also utilises the available wood in 30 oo any 'og to a far higher extent than with other conventional aei i±ling methods. Up to 80% effective utilisation can be achie'ed with methods of the present invention, With laminated wood products according to the present invention it is possible to laminate the weaker thinner wood sections with the stronger thicker sections to achieve a strong and stable end product. This form of lamination also has the effect of relieving internal stresses in the wood in a balanced fashion while enabling the presentation of either a perfectly quartersawn surface or a backsawn surface on certain surfaces of the product formed in various preferred embodiments of the method of the present invention.

The methods of the present invention also makes it possible to utilise smaller logs than would be necessary with conventional milling methods. This then makes it more attractive to use plantation forestry or regrowth timbers where valuable timber products can be formed from small i0 tress thinned out as well as the larger trees when fully grown. The ability of milling smaller logs also makes their handling easier at all stages of production. This method is particularly advantageous with small diameter trees with 15 high growth stresses which cause problems when being converted by conventional methods.

0 0 o A number of preferred embodiments will hereinafter o obe described with reference to the accompanying drawings in which S2 Figure 1 is a schematic cross-sectional view f a o .o 20 2Q. log demonstrating the difficulties associated with products Sof conventional milling techniques due to different shrinkage rates across and parallel to the growth rings; Figure 2 is a view similar to Figure 1 showing a sawing pattern according to one embodiment of the present 25 invention; Figure 3 illustrates schematically one form of ~apparatus for sawing a log according to Figure 2; Figure 4 illustrates schematically a second form of cutting a log in accordance with the present invention; Figures 5, 6, 7 and 8 illustrate schematically different forms of laminated timber products according to the present invention; Figure 9 illustrates a second form of laminated timber product; Figure 10 illustrates the use of the laminated product of Figure 9; l II- 6 Figure 11 illustrates a still further form of laminated product; Figure 12 illustrates schematically a means for drying timber sawn initially in accordance with the present invention; Figure 13 illustrates schematically a further preferred embodiment of cutting a log into wedge shaped elements; and Figures 14 to 16 are illustrative of various 1 laminated products formed from cutting a log as shown in Figure 13.

Referring initially to Figure 1, a log is illustrated schematically in cross-section showing some forms of milling. The plank shown at 11 is quartersawn, that is the growth rings are as near as possible arranged at right angles to the major side surfaces of the plank. The S'o2 shrinkage that occurs with planks thus sawn is primarily o parallel to the major side surfaces, however the S cross-section remains essentially rectangular without any o 0 lateral warping. The square sections and round sections 20 shown at 12 and 13 are more or less quartersawn although S because of their greater width there is a greater tendency for lateral warping to occur when the product shrinks. The plank shown at 14 is then backsawn and is the exact opposite to the quartersawn plank 11. In this case there is the *o greatest risk of lateral warping as illustrated upon the plank shrinking during drying. Moreover, the plank major S surfaces have a minimum of the harder growth rings and consequently in some species its appearance and wearing or strength characteristics are impaired. Finally, the square section at 15 is equally likely to shrink and become distLrted as shown because of its arrangement relative to the log growth rings. Clearly a quartersawn plank provides the best stability and the hardest wearing product and in 3 many species may combine this with the most attractive appearance, however, it is impossible to cut most logs economically to achieve completely quartersawn products.

7 Figures 2 ar.d 3 illustrate a sawn cross-section of log and schematically a cutting apparatus to achieve this cutting pattern in accordance with the present invention.

As shown in Figure 2, the log 16 is cut by a plurality of radial (and longitudinally extending saw cuts 17 extending from the periphery 18 of the log towards its centre. In most instances the angular spacing between the cuts 17 will be equal although with the preparation of some laminated products, as explained hereinafter, it may be desirable to have some of the cuts at different angular spacings, for example, half the angle of the majority of the other saw cuts. Figure 3 illustrates schematically a cutting machine 19 for achieving the configuration shown in Figure 2. The machine 19 comprises two circular saw working heads 20,21 mounted to travel along supporting and guiding rails 22.

The rails 22 are mounted parallel to the longitudinal axis of the log 16 to be sawn which is mounted on spindles 23 S' permitt.ng selective rotation of the log through a predetermined angle of movement. Each working head 20,21 is S, mounted on suppoit arms 24,25 that are pivotable about the o ,20 point 26. Each head 20 or 21 can be lowered a prescribed amount into the log 16 by rotating the heads around the point 26 by use of a control device 27. Each cutting head is rotated in the desired direction and cuts are made by relative movement of the log and cutting head. Cuts can be made towards the centre of the log in each direction of travel or in one complete pass. Furthermore, it is possible to have one of the heads 21 cutting radially while the other cutting head cuts tangentially (or at an angle to the tangent). Drive means for the respective working heads may be from a common drive to the point 26 with pulleys or the O like transferring this drive to the working head, or alternatively, or in combination with, by separate electric or hydraulic motors arranged at the working head. The cutting heads themselves may be any desirable cutter or shaper elements including circular saws and other cutting saws, hoggers and shaders. It is possible also to arrange two or more cutting or shaping elements in the one head.

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8 The spindles 23 that hold the log during cutting may dog into the end of the log so that the inner end 28 of the radial saw cuts 17 extend longitudinally along most of the log at a uniform depth but at each end the line 28 diverges outwardly to leave an amount of uncut timber to hold the section together. In addition, as shown in Figure 2, the inner end of the saw cuts may terminate less than half way through the log to leave a central portion 29 uncut. Alternatively, these cuts can go right to the centre with the log being held together only by the end sections adjacent the spindles 23. Alternatively, spindles could dog into ends of a log allowing cuts at predetermined angles to go to the centre of the log through ends of the log leaving segments held by fingers of the sprindle dogging into the log. The machine may include auxiliary devices for inserting spacers into the cuts made, for compressing softwood logs and supporting long hardwood lodgs and in some °o instances, for enabling sideways travel of the working Sheads. Figure 4 illustrates another method of cutting a log n oo 9 S in accordance with the present invention. In this case the o O~o 20 log 16 is bandsawn in half and each log half is separately tO' attached to an offset table 30 and is rotated around the cutting axis 31. In this case individual segments 32 are produced which may be used green or dried using conventional methods or any of the methods hereinafter described.

iAfter the log has been initially cut as described in the foregoing, it may be dried using any of the following techniques. One such technique might be simply to leave the log cut but not separated until the log has naturally dried.

Another method might be to wrap the cut logs in a porous or 30 o o non-porous membrane and have hot air forced through it.

o Alternatively, the log might be placed in a cylinder of Ssimilar but slightly larger dimensions and dried by vacuum or by forced movement of air through the cylinder. These 35 cylinders might operate as individual units for precise control of the drying environment or a number of logs might be placed in a long cylinder or dried on a continuous feed i 9 system as the logs move through the cylinder. Figure 12 illustrates a still further possible drying arrangement where the logs are placed in a container 33 with an inclined bottom surface 34 such that they roll downwardly thereon to be eventually discharged at the lower end. New logs 16 are loaded sideways at the upper end of the container 33 with hot air 35 being introduced at the lower end.

Once a log 16 has been cut according to Figure 2, (and dried and treaded, if desired, as aforesaid), it may be cut into individual wedge shaped elements by dividing the log in half, separating the log halves and passing a rotary cutter centrally down the log halves to remove the central uncut wood portions. If the radial cuts have passed to the centre of the log and the log is held together only by uncut end sections, then it is only necessary to remove the uncut end sections to separate the individual wedge shaped elements.

^i Figures 5 to 11 illustrate various forms of laminated wood products using wedge shaped segments formed 2 as aforesaid. Figure 5 shows two elements 36 (glued, nailed a oa or combination of gluing or other mechanical fasteners, nailing) at side faces 37 to form a laminated product. The portions 38 shown in dotted outline may be removed either before or after laminating to form a rectangular product With the major outer faces 39,40 providing perfectly 0 Do ,o quartersawn faces. Figure 6 shows a somewhat similar lamination technique wherein a plurality of Wedge shaped seoo: elements 36 are laminated together at mutually engaging side S faces 37. In this case the two end elements 36' and 36" are 3 half the angle of the other elements 36 to form a 9 rectangular product, Again the portions 38 shown in dotted outline might be removed before or after lamination. With this product it might be possible to further divide the section by cutting along one or more lines parallel to the outer surfaces 41 and 42. Figure 7 is similar to Figure 6 except that only one element 36 is laminated with half angled elements 36' and 36" to form the laminated end

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4 4 4 0 4 0 4 10 product. Again with this product the major outer surfaces 43 and 44 are perfectly quartersawn. Figure 8 illustrates a variation of Figure 5 wherein the lamination line 37 does not extend from corner to corner of the end product. The sections 38' and 38"1 may be removed before or after lamination. In all the aforesaid products the growth lines of the wood of each element are substantially parallel.

Figure 9 illustrates a further preferred embodiment, particularly suited for forming a floorin.g or panel board product. In this instance two wedge shaped elements of similar c ross-sec t~.o nal shape 45 and 45' are lamninated together (preferably by gluing) along the edge surfaces 46 and 46' joining the respective side surfaces 37 and 37' at the thicker ed'ze of the elements. The arrangement is such that the growth linen of each element 45,45' are essentially parallel with one another and the respective faces 37 and 37' of each element are parallel with one another and present a perfectly quartersawn face.

Ott Furthermore, the two elements 45 and 45' are offset relative 20 to one another to form upper and lower steps 47,48. F'igure 10 illustrates the use of a laminated product as shown in figure 9 as flooring. in this flooring construction the laminated prodcts are laid overlapping one anothier and adjacent one another and can in each instance be nailed 625 through the hidden surface 37' of each product. As i~s apparent from the drawings, the narrow edge of the wedge locks under the angled step in the edge of the exposed end face which mechanically locks the boards together in addition to the nailing. These angles may need to be 30 machined into the product, The respective upper surfaces 37 are all perfectly quartersawn providing a high quality hard wearing appearance. The respective elemients 45 and might be produced from different timber species to provide a cheaper but compatible wood for the lower element Laminat,;d products according to Figure 9 may also be used in larger laminations where two or more such products are joined with adjacent elements being laminated by gluing surfaces 37' together. A single wedge shaped element may then be glued to either end.

a 44 4 444 4 *44 a 4 44 44 444 4 1 .l~i 1_Y 11 Figure 11 illustrates a further form of laminated product where individual wedge elements 47 are glued together into an annular shape. The outer surface 48 might be circular or might be shaped as desired, as indicated by the line 49. This type of product might be useful as poles, masts or turning blanks, The individual wedge shaped segments should have a dimensionally stable cross-sectional shape not warped), be straight along the longitudinal plane at right angles to the face tangential to the growth rings, but may be curved longitudinally as a result of varying growth stresses. Segments may need to be machined before they are laminated. Segments, sitting on their tangential faces may be passed over two fined rollers and onto further movable rollers controlled by a sensing device which determines the degree of curvature of each segment. The segment may be held to the tangential rollers by angled rollers placed strategically. The segments may be machined after passing over the fixed rollers by the desired number of angled cutters, rotary planers or sanders. Segments may then be glued together using forces causing the curvature of the segments to an advantage. One means of achieving this is to place the machined segments to form a rectangular section with the segments being held to a desired width and adhesive 25 applied between the contacting surfaces. Subsequently pressure can be applied by rollers operating from a central zone towards the lonyitudinal ends of the segments to achieve pressure application with a minimum of clamping devices. Segments might also be nail laminated by clamping one end together in the desired position and forcing a roller from this end to the other end nailing as the roller passes. If the segments s'e green, the nail can protrude to assist with stacking aud drying and the segments pressure rolled after drying to clinch nails and remove shrinkage gaps between segments.

Figures 13 to 16 illustrate a further alternative method according to the present invention. In this

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0 a o 0 4 4 0 12 embodiment (Figure 13) cuts are made by a suitable saw 54 radially along longitudinal planes 50 from the centre of the log 16 to a distance approximating a veneer thickness from the outside periphery 18 of the log. This may be done as illustrated by the application of heat and/or chemicals to the log with the outside circumference being laid flat in the direction of the arrow 51 with distortion of the fibres in the uncut section similar to that which occurs with rotary cutting of veneers. As an alternative to that which is shown in Figure 13, the log might be halved prior to cutting in a similar fashion. In either case the wedge shaped elements 52 are interconnected by veneer width portions 53 as shown in Figure 14 where a section of log is shown laid out in an extended fashion. The tips of the wedge shaped elements 52 are removed along line 55 so that the shape of the wedge shaped elements 52 will be essentially complimentary to the spaces therebetween. In °o one embodiment shown in Figure 15, the length of the wedge shaped elements might be halved by cutting along line 56 so 20 that the removed tip parts 57 might be laminated between the S remaining parts 58 of the wedge elements 52 to form a completed laminated timber product. Figure 16 illustrates a second embodiment where two cut members according to Figure 14 having individual wedge shaped elements 52 and 52' are laminated together. Subsequent to lamination, the rodutct may be machined as desired to achieve the required cross-sectional shape.

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Claims (9)

1. A method o. sawing a complete log to produce elongated wedge shaped elements the said method comprising the steps of: mounting said complete log (16) for rotation about a central longitudinal axis extending through said log (16); arranging cut';lng means (20, 21, 54) adjacent said log and creating a radial cut (17) in said log extending to a predetermined depth so that in combination with subsequent cuts an uncut portion of the log at an apex of two radial faces is left attached to an uncut central core of a log or so that the apex of the radial faces is just severed from parts of said log adjacent said central longitudinal axis but essentially remain in position with the remainder of said log; establishing relative movement between said cutting means and said log whereby *said radial cut is extended longitudinally along said log (16); withdrawing said cutting means from said log (16) and rotating said log (16) through a predetermined angle; operating said cutting means to form a further radial longitudinally extending cut (17); repeating steps and until a plurality of and the desired number of said radial longitudinally extending cuts are formed In said log.

2. A method according to Claim 1, wherein spacers are Inserted into the cuts (17). 2 3, A method according to Claim 1, wherein said cut log is subject to drying and/or treating.

4. A method according to any one of Claims 1 to 3, wherein each said radial cut (17) extends to said predetermined depth with uncut end portions of said log (16) holding said log in one piece, A method according to any one of Olaims 1 to 3( wherein each said radial cut (17) extends at least to said dep ,lth said log (16) being held In one piece by spindle means mounted to opposed ends 3ald log (16). r"^ H^T 14

6. A method according to Claim 1, wherein said cutting means cuts or machines a peripheral flat or shaped surface (46, 46 on said log (16) simultaneously with or subsequently to each said radial cut (17).

7. A method according to any one of Claims 1 to 3, wherein said cutting means is mounted for movement longitudinally relative to said log said cutting means comprising at least one circular saw, the or each said circular saw being mounted on a pivoted arm for movement towards or away from said log.

8. A method according to Claim 7 wherein two said circular saws are provided whereby one said circular saw operates to form a said radial longitudinally extending cut the other said circular saw being withdrawn and vice versa.

9. Apparatus r forming timber products from a complete log, said apparatus i;i comprising log mounting means adapted to support opposed ends of said log enabling said S;log to be rotated about a central longitudinal axis extending through said log, cutting l means arranged adjacent to said log when mounted with said log mounting means to form a radial cut in said log; means to relatively move said log and said cutting means in a longitudinal direction to extend said radial cut along said log; and means to rotate said log through selected predetermined angles to repeatedly form radial longitudInally extending ""cuts in said log separated by said predetermined angles. Apparatus according to Claim 9, wherein said cutting means cuts or machines peripheral longitudinally extending flat or shaped surface on said log simultaneously or on alternate passes with each said radial cut (17),

11. Apparatus according to Claim 2 or Cl im 10, wherein said cutting means Is/are mounted on one or more working heads, the or each said working head being movable laterally relative to said longitudinal direction, 12, Apparatus according to Claim 11, wherein said cutting means Includes two s.4l circular saws (20, 21), each said saw being mounted on a pivotal arm (24, arranged such that when one said circular saw is operating to form a said radial longitudinally extending cut the other said circular saw is withdrawn and vice :versa. 13 A timber product comprised of two elongated wcdge shaped elements (45, 45') 1 each having two side surfaces (37, 37') angled towards each other forming an a e angle therebetween and an end surface (46, 46') forming said side surface, e of said wedge shaped elements having growth rings extending substantially b een said side surfaces and perpendicular to said side surfaces, said two elo ted wedge shaped elements being laminated together by facing said end surfae (46, 46') together.

14. A timber product according to Claim 13 erein said end surfaces (46, 46') are offset relative to one another. A timber product com sed of a plurality of elongated wedge shaped elements o each having two side rfaces angled towards each other forming an acute angle a therebetween an n end surface joining said side surfaces, each of said wedge shaped elements h ing growth rings extending substantially between said side surfaces, said Selon ed shaped elements being laminated together by facing said side surfaces together DATED this 13th day of August, 1991 ""ANDREW KARL KNORR 0 WATERMARK PATENT TRADEMARK ATTORNEYS THE ATRIUM 44 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA SKP:JJC f it^ 1