BLANK FOR MANUFACTURING A LAMINATED PLATE OR A LAMINATED BEAM PLATE

Abstract: The invention relates to a blank for laminated beam plates, comprising an elongated piece of wood with a specific shape, including two planear lateral surface sections (2, 3) and a lower surface section (4) and an upper surface section connecting these. Said upper surface section comprises an elongated, ridge-shaped tip section (5), and, between each lateral surface section (2, 3) and the tip section (5), a first planar surface section (6; 9) to be glued and a second planar surface section (7; 10) to be glued and a planar intermediate surface section (8; 11) connecting these. Said first surface section (6; 9) and said second surface section (7; 10) are mutually parallel and the width a of said first surface section (6; 9) is equal to the width b of said second surface section (7; 10) and the width c of the intermediate surface section (8; 11) is half of the width a or b. In addition, the angle alpha between the intermediate surface section (8; 11) and said second surface section (7; 10) is equal to the angle of opening beta of the ridge-shaped tip section (5), which is preferably in the range of 90 to 135 DEG .

Description: Blank for manufacturing a laminated plate or a laminated beam plate The invention relates to a blank comprising an elongated piece of wood with a specific shape, having two planear lateral surface sections and an upper surface section and a lower surface section connecting these. These blanks are used to manufacture laminated beam plates, which may be further used for the manufacture of laminated plates or laminated beams or other products. It is previously known to produce laminated beams from strength-graded pieces of wood rectangular in cross-section, which have been sawn from logs, yielding an overall quality higher than the average and suitable for the manufacture of a laminated beam. Usually such pieces of wood are glued by means of a beam press after drying. When manufacturing laminated beams, they are worked all over after gluing. A laminated beam produced in this manner is not appropriate for all purposes of use and tends to warp. As a rule, so-called laminated plates are manufactured of batten strips sawn out of an approx. 45 mm thick batten, by gluing the strips with a "friction press". Though less frequently, laminated plates can also be made by slicing laminated beams vertically by means of a deal bandsaw. Laminated beams and plates are usually made of logs, which are expensive compared to small-dimensioned wood. What is more, the log consumption will be high when laminated beams and plates are manufactured with the methods described above. The cubic metre log consumption for each product mentioned above is calculated as follows: - a minimum of 2 m 3 of logs per 1 m 3 of sawn timber, - a minimum of 1.75 m 3 of sawn timber, i.e. a minimum of 3.5 m 3 of logs per 1 m 3 of laminated beam, - a minimum of 2.3 m 3 of sawn timber, i.e. a minimum o 4.6 3 of logs per 1 m 3 of laminated plate. One should also take account of the fact that the entire sawn timber yield from logs will not be appropriate for the manufacture of a laminated beam, nor for the manufacture of a laminated plate. The object ofthe invention is to provide a blank which can be manufactured from less expensive small-dimensioned wood and has a profile allowing small- dimensioned wood to be very effectively used, and also allows laminated beam plates with excellent strength properties to be manufactured. These objects have been achieved with a blank in accordance with the invention. whose main characteristics are defined in the characterising clause of accompanying claim 1. The blank in accordance with the invention is advantageously made of small- dimensioned wood, which costs about one third ofthe price of logs. The blank in accordance with the invention is made by working small-dimensioned wood such that it directly adopts its final shape, resulting in a very high yield. The lower surface section mentioned above is preferably planear, and then small- wood core cleaving and sursurface profiling result in two blanks in accordance with the invention. In fact, to operate with great accuracy, small-dimensioned wood is split to the core by exactly positioning the small-dimensioned wood with the aid ofa tracer such that the core is hit by the saw-slit, using for instance a log sawband. and by profiling the halves with a machine provided with two upper horizontal spindles. The reason for this is that the timber core is by no means located in the centre ofthe cross-sectional sursurface. The lateral sursurface sections mentioned above are preferably mutually parallel and also in right angles to said lower sursurface section. The invention will be described in greater detail below, with reference to the accompanying drawing, in which figure 1 A is a cross-sectional view of a blank in accordance with the invention, figure IB is a view of the same structure as in figure 1 A, provided with dimension marks, figure 2 is a cross-sectional view of small-dimensioned wood, in which the splitting and profiling lines have been marked, and figure 3 is a view of a laminated beam plate made of blanks in accordance with the invention. Referring to figures 1 A and IB, the blank 1 ofthe invention is an elongated, e.g. 3 m long wooden piece with a given shape, which has been made of small- dimensioned wood. This blank 1 has a planear lower surface section 4 and two mutually parallel planear lateral surface sections 2 and 3, which are in right angles to the lower surface section, and an upper surface section. This upper surface section comprises an elongated, ridge-shaped tip section 5. Between the left lateral surface section 2 and the tip section 5 there is a first planear surface section 6 to be glued, and a second planear surface section 7 to be glued, the surface sections 6 and 7 being connected by a planear intermediate surface section 8. Accordingly, between the right lateral surface section 3 and the tip section 5, there is a first planear surface section 9 to be glued and a second planear surface section 10 to be glued, the surface sections 9 and 10 being connected by a planear intermediate surface section 1 1. The blank in accordance with the invention meets the following conditions - the width a ofthe first surface section 6 (and 9) = the width b of the second surface section 7 (and 10), - the width c ofthe intermediate surface section 8 (and 1 1 ) = l/2a = l/2b and - the angle α between the intermediate surface section 8 (or 1 1 ) and the second surface section 7 (or 10) = the angle of opening β of the tip section. In the example illustrated in figures IA and IB, the angles α and β are approx. 90 °. Figure 2 shows a cross-section of small-dimensioned wood 13. from which the blanks 1 of the invention are made for instance by using a profiling chipping canter. After drying, these blanks 1. turned to surface each other, are glued by means of a hotizontal press, forming a laminated beam plate 12. whose structure is illustrated in figure 3. In accordance with the invention. the consumption of circular small-dimensioned wood is only approx. 1.5 m 3 per cubic metre of plate, whereas conventional laminated plate manufacture requires approx. 4.6 m 3 of logs and conventional laminate beam manufacture requires approx. 3.5 m 3 of logs per 1 m 3 of product. Moreover, the price of small-dimensioned wood is only about one third ofthe price of logs. The grain pattern on the sursurface of the laminated beam plate manufactured from blanks ofthe invention will meet current requirements in the market in that the growth rings will be peφendicular to the sursurface. When small-dimensioned wood with an adequate diametre is used for the plate thickness concerned, the plates will result in mutually identical, homogenous products, and this is not one of the best features of a laminated plate manufactured with conventional methods. This plate is perfectly suitable as a laminated beam owing to its glued, symmetrical structure. Such a structure does not warp, which is often the case with conventional laminated beam structures. The blank ofthe invention enables a very economical laminated beam plate to be made from small-dimensioned wood by using straightforward means and methods as follows: 1. Splitting the small-wood core and surface profiling with a suitable machine. 2. Piling the plate blanks as a drying plant load and subsequent drying. In doing this, a longitudinal through-drying plant or a high-frequency vacuum drying plant are usable. 3. Planing the blank to measure and gluing in connection with the planing. To manufacture a long plate, the blanks may be finger-jointed before planing. 4. Piling the blanks provided with glue at the input end of a gluing press and gluing the blanks. Because wood dries and shrinks simultaneously over its entire cross-sectional surface in high-frequency drying, it is possible to anticipate the shrinkage. This allows the blanks to be provided with glue while fresh and the high-frequency vacuum dryer plant to be equipped with a press. As explained above, laminated plates and laminated beams can be manufactured from a laminated beam plate made from blanks in accordance with the invention by sawing longitudinally. In addition, building log blanks, window blanks, or similar blanks for the most varying purposes can be obtained from the laminated beam plate by sawing longitudinally, and decorative end grain patterns for instance for a floor board can be obtained by sawing transversely.

Claims: Claims 1. A blank ( 1 ) for a laminated beam plate ( 12) comprising an elongated piece of wood with a specific shape, including two planear lateral surface sections (2, 3) and a lower surface section (4) and an upper surface section connecting these, characterised in that said upper surface section comprises an elongated, ridge- shaped tip section (5), and between each lateral surface section (2, 3) and tip section (5), a first planear surface section (6; 9) to be glued and a second planear surface section (7; 10) to be glued and a planear intermediate surface section (8: 1 1 ) connecting these, in that said first surface section (6; 9) and said second surface section (7: 10) are mutually parallel, in that said first surface section (6; 9) has a width a equal to the width b of said second surface section (7; 10) and that the width c of the intermediate surface section (8; 1 1 ) is half of the width a or b, and in that the angle ot between the intermediate surface section (8J 1 ) and said second surface section (7: 10) is equal to the angle of opening β of the ridge-shaped tip section (5). 2. A blank as claimed in claim 1. characterised in that angles ot and β are approx. in the range of 90 to 135 °. 3. A blank as claimed in claim 1 or 2. characterised in that the lower surface section (4) is planear. 4. A blank as claimed in any ofthe preceding claims, characterised in that the lateral surface sections (2. 3) are mutually parallel. 5. A blank as claimed in claim 4. characterised in that the lateral surface sections (2, 3) are in right angles to the lower surface section (4).

Inventors: FAGERROOS JORMA TAPANI, PITKAENEN RISTO HEIKKI, FAGERROOS, JORMA, TAPANI, PITKAENEN, RISTO, HEIKKI
Applicants: FAGERROOS JORMA TAPANI, PITKAENEN RISTO HEIKKI, FAGERROOS, JORMA, TAPANI, PITKAENEN, RISTO, HEIKKI
Application year: 1996
Main classification: B27M3
IPC codes: B27M3