A METHOD OF FIXING A WOODEN SHEET OF VENEER TO A SUPPORTING LAMINA

Abstract: A method of fixing a wooden sheet of veneer (3) to a supporting lamina (1). To avoid the great loss of material in known methods a very thin, 0,2-0,3 mm, sheet of veneer (3) is used. The sheet of veneer (3) is moist to form a humidity buffer which prevents the glue (2) from penetrating up to the front surface of the veneer during the glueing-step.

Description: A method of fixing a wooden sheet of veneer to a supporting lamina The invention relates to a method of fixing a wooden sheet of veneer to a supporting lamina. In hitherto known methods there used 0,7-1,7 mm thick wooden sheets of veneer, which are fixed to a supporting lamina. Before the fixing the sheets of veneer are dried, and in the next step the sheet of veneer is cemente to the lamina. When a very thin sheet of veneer is wanted, the planing or sanding of the veneer is carried out after fixing t sheet of veneer to the supporting lamina, because the glueing not been possible to carry out with very thin sheets of veneer to the fact that with a very thin sheet of veneer the glue wil penetrate through the sheet into the front surface of the vene That is why there has been a great loss of material in prior a methods. The object of the present invention is to eliminate the above- mentioned disadvantages of known solutions for fixing a wooden sheet of veneer to a supporting lamina. This is achieved in accordance with the invention by a method which a moist, very thin, preferable 0,2-0,3 mm thick sheet of veneer is placed on a pre-glued surface of the supporting lami after which they are glued together and dried by using hot- pressing so that the humidity buffer which is achieved by the compression and the heat prevents the glue from penetrating u to the front surface of the veneer. By means of this method it is achieved a thin sheet of veneer without any loss of material. Penetrating of the glue onto the front surface of the veneer is prevented by the humidity buff which is formed due to the moist veneer. By hot-pressing the of veneer to the supporting lamina the glue will penetrate in the back side of the veneer, and due to the heat it will dry fix the lamina to the veneer. Due to the moist of the veneer th humidity buffer will prevent the glue from damaging the front surface of the veneer. At the end of the hot-pressing the heat will also dry the upper, front surface of the veneer, but by th time the glue has already dried, and will not anymore penetrate up to the front surface of the veneer. So as to prevent the water vapour from evaporating from the veneer during the step of hot-pressing it is advantageous to us a hermetically sealed planar press. Usually the moisture content of a newly felled tree is great enough for achieving the required humidity buffer. If the tree has dried due to the influence of air, the veneer should be moistured before the step of glueing. This could be achieved b dipping, for instance. It is also advantageous according to the invention to transport the veneer from the cutting station to t glueing station on a water cushion transporting device. By this transporting device the friction is very small and at the same time the veneer will be moistured. According to the invention the supporting lamina can be made of paper, plastic, fibreglass, woven, non-woven, plywood, hardboa gypsum board or wooden board. According to the method of the invention it is achieved a very thin and strong, good-looking veneer without loss of material. The method is also relatively inexpensive because of the very required steps. Also the achieved veneer reacts very little at changes of temperature and humidity due to its very small mass. The invention is described below in greater detail with refere to the accompanying drawings, in which Fig. 1 is a sectional view of the sheet of veneer, Figs. 2-4 show the procedure with a scarf joint as a sectional view, Fig. 5 shows the scarf joint from the front surface of the ven In the first step the sheets of veneer 3 are cut to a thicknes of 0,2-0,3 mm. If they have dried, they are first moistured an in the next step they are placed on the pre-glued 2 surface of supporting lamina 1. The joints between adjacent sheets of ven can be made as butt joints or as scarf joints. If butt joints used, the edges of adjacent veneers are cut straight-lined, an the edges of the veneers are placed against each other. Scarf joints are described below referring to Figs. 2-4. In Fig. 1 there is shown the effect of the pressing 10 and the heat 11. The moist of the veneer goes upwards, shown with reference number 12. The glue 2 will penetrate into the dry cells 3' only for such a distance that the cells have dried. The glue will not penetrate into the top of the veneer because the humidity buffer that is achieved by the moist veneer. At t same time the glue penetrates into the supporting lamina. In Figs. 2-4 there is shown a solution in which a scarf joint used for scarfing sheets of veneer to each other when fixing t on a supporting lamina 1. In Fig. 2 there is shown how the she of veneer 3 and 4 overlap. In Fig. 3 the heat pressing is performed as explained above, and in Fig. 4 the overlapping pa 8 of one of the sheets is removed. This can be achieved e.g. through blasting air with high pressure on the overlapping par of the sheet, whereby the dry edge 8 can be removed, and a qui good joint 9 is achieved. In Fig. 5 there is shown a solution whereby a scarf joint is used with a non-straight-lined joint 9. Hereby the joint 9 fol the fibres of the tree and the joint will be very natural and imperceptible .

Claims: Claims 1. A method of fixing a wooden sheet of veneer to a supporti lamina, c h a r a c t e r i z e d in that a moist, very thin, preferable 0,2-0,3 mm thick sheet of veneer (3) is placed on a pre-glued (2) surface of the supporting lamina (1), after whic they are glued together and dried by using hot-pressing so tha the humidity buffer which is achieved by the compression and t heat prevents the glue from penetrating up to the front surfac of the veneer (3). 2. A method according to claim 1, c h a r a c t e r i z e d in that the moisture content of the wooden sheet of veneer (3) equal or greater than that of a living tree. 3. A method according to claim 1 or 2, c h a r a c t e r ¬ i z e d in that the sheet of veneer is moistured to the saturation point before the step of glueing. 4. a method according to claim 2 or 3, c h a r a c t e r ¬ i z e d in that the moisturing step is carried out on a water cushion transporting device, which is transporting the veneer form the cutting station to the glueing statio . 5. A method according to any of the above claims, c h a r a t e r i z e d in that the supporting lamina (1) is made of pa plastic, fibreglass, woven, non-woven, plywood, hardboard, gyp board or wooden board. 6. A method according to any of the above claims, c h a r a t e r i z e d in that the step of hot-pressing the wooden she of veneer (3) onto the supporting lamina (1) is carried out wi a hermetically sealed planar press such that the water vapour does not evaporate from the surfaces during the step of hot- pressing.

Inventors: PAUKKUNEN YRJOE, STRAHL ECKHARD, PAUKKUNEN, YRJOE, STRAHL, ECKHARD
Applicants: KALLENMAKI OY, STRAHL KY, KALLENMAEKI OY
Application year: 1985
Main classification: B27D1
IPC codes: B27D1, B27G11, B32B21