AU730188B2

AU730188B2 - Method and apparatus for laying a stack of wood veneer sheets

Info

Publication number: AU730188B2
Application number: AU73990/98A
Authority: AU
Inventors: Matti Eerola
Original assignee: Raute Wood Oy
Current assignee: Raute Wood Oy
Priority date: 1997-07-02
Filing date: 1998-07-01
Publication date: 2001-03-01
Anticipated expiration: 2018-07-01
Also published as: AU7399098A; CA2242286A1; CA2242286C

Description

S F Ref: 425804

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

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S

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Raute Wood Oy Rautetie 2 Nastola FIN-15550

FINLAND

Matti Eerola Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Method and Apparatus for Laying a Stack of Wood Veneer Sheets The following statement is a full description of this invention, including the best method of performing It known to me/us:- 5845 Method and apparatus for laying a stack of wood veneer sheets The present invention relates to a method of laying a stack of wood veneer sheets, and further, to an apparatus suited for implementing said method.

In the fabrication of a gluelam beam, the gluelam beam block is made by forming a stack from a plurality of single wood veneer sheets, coated by a glue layer, by way of successively laying the sheets onto each other according to a preset scheme. From such a layup, the actual gluelam beam is then finished by hotpressing, whereby the gluelam beam attains its final thickness and the glue bonding the wood veneers to each other is cured.

o In a continuously-operating layup line, the laying is performed in successive stacks so that the end-to-end joints of wood veneers belonging to successive stacks are preferably located at staggered points in the superimposed wood layers in order to avoid an abrupt discontinuity in the joint between the ends of the successive sheet stacks.

As customary in the art, the layup is formed so that the wood sheet to be laid is moved by a laying conveyor, located above the layup, until the leading edge of the sheet hits a stop. The stop is positioned so as to stop the wood sheet in its intended laying position in which the sheet is lowered with its leading edge first meeting the layup when the delivery-type laying conveyor is reversed from below the sheet. However, this type of laying technique is hampered by a number of inaccuracy-causing weaknesses such as backbouncing of the sheet from the stop. Obviously, the result is an imprecise positioning of the sheet in the layup, whereby an undesirable gap may remain between ends of the preceding sheet and the sheet being laid.

2 By virtue of the present invention, using otherwise a technical implementation chiefly based on the prior art, it is possible to achieve an accurate positioning of the sheet in the line direction of the layup through an arrangement in which, before being laid on the stack, the sheet is lowered with its tailing edge first onto an intermediate platform located above the layup position.

According to the present invention there is provided a method of forming a layup stack of wood veneer sheets, which comprises first taking each of the sheets separately 1o into a forward-feed position on a level situated above the layup stack, in which position a leading edge of the sheet is aligned essentially at the desired laying point in the layup stack, wherein, when stopped in this position, the sheet is further lowered onto an intermediate level with a tailing edge of the sheet being first, the tailing edge is aligned with regard to the layup stack during the lowering, and the sheet is lowered further, 15 keeping the tailing edge aligned, on the layup stack with its leading edge first.

o° According to a further aspect of the invention, there is provided an apparatus suitable for implementing the method described above.

The method according to the invention can be implemented by means of an apparatus comprising an endless-loop conveyor with a width wider than the cut width of the sheet, the endless loop of said conveyor consisting of an essentially horizontal feed -section longer than the sheet length and of a corresponding return section, and said oooconveyor being formed from two toothed belts or similar elements running in the line direction and from transverse bars or similar elements connecting said belts. According S• to the invention, the conveyor is arranged to perform a continuous loop motion during the entire laying step, the conveyor having its connecting bars or similar elements omitted from a section somewhat shorter than the length of the sheet being laid, and said apparatus including a sheet leading edge stop for stopping the sheet travel at the end part of the line-direction feed section of the feed conveyor and a sheet tailing edge stop for stopping the sheet travel at the end part of the return section of the feed conveyor, respectively.

In the following, the invention is described in greater detail with reference to 4appended drawings in which [R:\LIBTT]02637.doc:SSL Figure 1 shows a sheet laying apparatus according to the invention in its different operating steps a-e, and Figure 2 shows the cross section of the laying apparatus along plane A-A.

[R:\LIBTT]02637.doc:SSL Referring to Fig. 1, the laying apparatus shown therein comprises a basically conventional, essentially horizontal feed conveyor 6 adapted to operate above a transfer conveyor 5 that supports the layup 2 to be formed and acts as a prime mover of said layup so as to run essentially parallel with said transfer conveyor. The basic structure of the feed conveyor includes two parallel-running, flexible conveyor means such as toothed belts 7.

The belts are passed over two turning rolls 8 so as to form an endless loop. The belts 7 are spaced apart from each other at a distance greater than the width of the sheets 1 being laid. The turning rolls 8 are outdistanced from each other sufficiently apart to permit the sheet being laid to be driven onto the horizontal section of 15 the feed conveyor 6 to be supported thereon.

For the support of the sheets, transverse support elements are provided between the parallel running belts.

According to a characterizing specification of the inven- 20 tion, said transverse support elements are omitted from a section of the feed conveyor slightly shorter than the length of the sheets being laid on the layup. In Fig. 1, this feed conveyor section is drawn with dashed lines free from support elements. In addition to these elements, the desired function of the invention requires the apparatus to be complemented with a sheet leading edge stop 3 placed at the outgoing end of the apparatus and a sheet tailing edge stop 4 placed at the ingoing end of the apparatus, respectively. The sheet leading edge stop 3 is adapted on the upper section of the feed conveyor 6, while the sheet tailing edge stop is adapted inside the loop of the endless-belt feed conveyor, above the return section of the feed conveyor.

The function of the laying apparatus will be evident from steps of Fig. 1. The transfer of the incoming sheet 1 onto the feed conveyor 6 must be synchronized so that a full-width-supporting section of the feed conveyor is introduced under the sheet over the entire travel of the sheet on the upper section of the feed conveyor when the sheet proceeds on the conveyor toward the sheet leading edge stop 3. The sheet leading edge stop is located approximately at the point where the sheet leading edge is intended to be situated in the final layup 2.

As the leading edge of the sheet meets the stop 3, the feed conveyor 6 continues its feed motion, whereby continued forward travel of the open section of the conveyor **from under the tailing end of the sheet permits the sheet *rear edge to drop into the position shown in Fig. Ic.

With the further continuing motion of the conveyor, also ***the sheet leading end is allowed to drop into the 15 interior loop of the conveyor, onto the return section of the conveyor, into the position shown in Fig. id. In this situation, the continuing motion of the feed conveyor 6 pushes the sheet tailing edge against the sheet tailing adge stop 4.

S. The sheet tailing edge stop 4 is precision-positioned so that the leading edge of the precision-length-trimmed sheet 1 will be located accurately on the layup 2 being formed. Resultingly, the correct positioning of the sheet on the layup is achieved by continuing the feed motion of the conveyor 6, whereby the leading end of the sheet will be dropped on the layup as shown in the steps (a) and of Fig. 1. During this dropping step of the sheet, a new sheet to be laid can be fed onto the upper section of the conveyor 6 and the operation of the apparatus is continued through the steps described above. In order to obtain a stepwise staggered joint of the layup 2, the feed conveyor 6 must be transferred forward by the desired displacement distance of the successive sheet layer joints before the front end of the next sheet is lowered onto the layup.

For the optimal overall function of the apparatus according to the invention, it is advantageous to have the feed roller track 9, on which the sheets 1 arrive to the feed conveyor 6, to be comprised of rollers which are aligned at a small angle rather than being axially perpendicular to the feed direction. Then, if that side of the roller track toward which the rollers are adjusted to lead the sheet is provided with a suitable lateral guide aligned parallel to the line direction of the sheets, the roller track will push the sheets laterally so as to make them run along said guide, whereby the sheets will be forced to fall onto said layup with an accurate positioning of 0 thus guided lateral edges of the sheets.

Claims

1. A method of forming a layup stack of wood veneer sheets, which method each of the sheets is first taken separately into a forward-feed position on a level situated above the layup, in which position the leading edge of the sheet is aligned essentially at the desired laying point in the layup and, when stopped in this position, the sheet is lowered onto the layup with its leading edge first, characterised in that, prior to the lowering of the sheet on the layup, the sheet is lowered with its tailing edge first onto to an intermediate platform situated above said laying point.

2. A method as defined in claim 1, characterised in that, during its lowering onto the intermediate platform, the tailing edge of the sheet is aligned with regard to the layup.

53. An apparatus suited for implementing the method defined in claim 1, said apparatus comprising an endless-loop feed conveyor with a width wider than the cut width of the sheet, the endless loop of said feed conveyor consisting of an essentially horizontal feed section longer than the sheet length and a corresponding return section and said feed conveyor being formed from two toothed belts or similar elements running in the line direction and from transverse bars or similar elements connecting said belts, 00 0 characterized in that said feed conveyor is arranged to perform a continuous loop motion during the entire laying step, that the feed conveyor has its connecting bars or similar elements omitted from a selection slightly shorter than the length of the sheet being laid, S. 25 and that said apparatus includes a sheet leading edge stop for stopping the sheet travel at oo*the end part of the line-direction feed section of the feed conveyor and a sheet tailing edge stop for stopping the sheet travel at the end part of the return section of the feed conveyor, respectively. 4. A method of forming a layup stack of wood veneer sheets substantially as hereinbefore described with reference to any one embodiment as that embodiment is illustrated in the accompanying drawings. [R:\LIBTT]02637.doc:SSL An apparatus suitable for implementing the method of claim 4 according to any one embodiment as that embodiment is illustrated in the accompanying drawings. Dated 5 December 2000 Raute Wood Oy Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON .e. 0o .o **e •g [R:\LIBTT]02637.doc:SSL