WO1989001857A1

WO1989001857A1 - Method for manufacturing floorboards, and floorboard manufactured according to the method

Info

Publication number: WO1989001857A1
Application number: PCT/SE1988/000444
Authority: WO
Inventors: Olav Hoel
Original assignee: Olav Hoel
Priority date: 1987-08-31
Filing date: 1988-08-30
Publication date: 1989-03-09
Also published as: SE8703354D0; SE8703354L

Abstract

Floorboards are manufactured by working boards unsorted in respect of quality to predetermined width and thickness. The boards are cut where necessary to remove board sections containing flaws (12) whereupon these board sections are split along their central plane and worked and glued in end-to-end relationship on the opposite flat sides of the flawless board sections (15) which also have been placed end to end, in accordance with the preferred method of the invention. The resultant assembly is split along the central plane of the last-mentioned board sections (15), and the strips are worked, tongued and grooved, and finished. A floorboard manufactured in this manner comprises a top layer of flawless board sections (15) of varying lengths and a bottom layer including board sections (14a, 14b) which contain flaws and have been cut from the starting material to provide the said flawless board sections (15).

Description

METHOD FOR MANUFACTURING FLOORBOARDS, AND FLOORBOARD MANUFACTURED ACCORDING TO THE METHOD

The present invention relates to a method for manufacturing floorboards comprising a top layer and a bottom -layer joined to said top layer by gluing. Timber floorings have been used from time im- memorial, and although many alternatives exist nowa¬ days, a great many floors are still laid with timber because timber has excellent properties for this type of use. Most timber floors consist of solid planks having a width of about 75-200 mm, a thickness of 8-25 mm or more, and normally a length of 0.3-4.8 m. The width depends on the diameter of the log from which the planks are cut, but is standardised to 75, 125 and 175 mm or, alternatively, 100, 150 and 200 mm. The length of the boards supplied to the floor-layer is entirely optional and normally varies between about 0.3 and 2.4 . The varying length is due to flaws which occur in the timber and as a result of which large parts of the timber must be cut off and discard¬ ed as waste. This means that the floor-layer is obliged to use relatively high-grade timber at high cost. Never¬ theless, the waste is considerable, and the varying length naturally makes the laying of the floor more complicated.

It is the object of this invention to provide opportunities for using lower grade timber, but yet avoiding waste in the manufacture of boards and pro¬ viding boards of desired or standardised length. This object is achieved by working boards unsorted in re¬ spect of quality to the desired width and thickness; cutting the worked boards where necessary to remove board sections containing flaws; and gluing the flaw- containing board sections end to end on at least one flat side of flawless board sections also positioned end to end, such that a continuous assembly is obtained which is cut to the desired lengths, worked, tongued and grooved, and finished.

In a preferred embodiment of the invention, the cut board sections containing flaws are first split along the central plane parallel to the flat sides and then worked and glued on the opposite flat sides of the flawless board sections, whereupon the result¬ ing assembly is split along the central plane of the flawless board sections parallel to the flat sides. The present invention thus makes it possible to utilise as starting material timber of greatly infe¬ rior grades than before, and to avoid at the same time practically all waste, which means that floor- boards can be manufactured in standardised lengths and at a far cheaper price.

The invention also relates to a floorboard com¬ prising laminates with a top layer of flawless board sections of varying lengths and at least one bottom layer including flaw-containing board sections cut from the starting material to provide the said flaw¬ less board sections forming the top layer.

It should here be emphasised that the above solu¬ tion to the problem of extensive waste and varying board lengths has nothing to do with the well-known techniques which are put into practice in the manu¬ facture of, for example, plywood and pieces of lami¬ nated parquet and which also use glued-together wooden layers, although for an entirely different purpose, i.e. for preventing movements caused by moisture.

The invention will be described in more detail below, reference being had to the accompanying drawings which are perspective views of embodiments. In Fig. 1, the starting material is worked to provide a board of predetermined width and thickness. Fig. 2 illu¬ strates the removal of a flaw-containing board sec¬ tion from the worked board. Figs. 3 and 4 illustrate the splitting and working of removed board sections con¬ taining flaws. Fig. 5 illustrates the application of glue to a flawless board, and Fig. 6 shows how flaw- containing board sections are joined with flawless board sections. Fig. 7 illustrates the splitting of the assem¬ bly formed by the glued-together board sections, and Figs..8, 9 and 10 illustrate the finishing of the strips obtained by the splitting operation shown in Fig. 7. The starting material for the manufacture of the floorboards according to the invention consists of un- sorted boards which, however, must have a fixed minimum width and minimum thickness. The boards 10 are planed as shown at 11 in Fig. 1. The planed boards 10 normally have flaws, such as knots 12, discolourations etc. that are not tolerated in a decorative layer. Such flaws must be removed, which is done by cutting off board sections, as shown at 13 in Fig. 2. In -this manner, the board 10 is divided into sections 14 containing flaws 12 and flawless sections 15. The sections 14 containing flaws 12 are then split, as.indicated at_.

16, to provide sections 14a, 14b of half the thickness (leaving the thickness of the splitting cut out of account). These sections 14a, 14b with flaws 12 are then planed in accordance with Fig. 4. The starting material for the floorboard according to the invention has now been obtained.

To manufacture the floorboard, the flawless board sections 15 are first coated with glue on their oppo¬ site flat sides, as shown at 17 in Fig. 5. Although this does not appear from the drawings, also the end faces are coated with glue. A desired number of flaw¬ less board sections 15 are then placed in a row in end-to-end relationship, and board sections 14a, 14b containing flaws 12, are pressed against the opposite flat sides of the board sections 15, as indicated by the arrows 18 in Fig. 6. Also the board sections 14a, 14b are placed in a row in end-to-end relationship, before which the end surfaces, if desired, can be coated with glue. Instead of making the ends of the board sec¬ tions abut end to end, they can also be finger-jointed. Care must be taken that the board sections are placed such that abutting end joints of the different layers do not come to lie opposite one another. The gluing indicated in Fig. 6 gives the assembly which is de¬ signated 19 in Fig. 7. In the subsequent work opera¬ tion, the assembly is split as shown at 20 along the central plane of the flawless board sections parallel to the flat sides, whereby two laminates 21 as shown in Fig. 7 are obtained.

The laminates 21 thus obtained are first planed as shown at 11 in Fig. 8 and are then tongued and grooved as shown in Fig. 9 by means of suitable milling tools 22 milling a tongue on one long side of the la¬ minate and a groove in the other long side, as shown at 23 and 24 in Fig. 9. The short sides are similarly tongued and grooved, whereupon the laminate 21 is fi- nished in accordance with Fig. 10, for example sanded (at 25) and varnished, if desired. The floorboard is now ready for use.

Although it is preferred to proceed as described above, a simpler way of achieving the object of the invention is to work the starting boards 10 already at the outset to final thickness and to glue the cut board sections 14 containing the flaws 12 to one flat side of flawless board sections 15, whereupon the resultant two-layer assembly is cut into the desired lengths which are worked, tongued and grooved, and finished in the manner described above.

By the above technique, boards of predetermined lengths can be manufactured, although it is preferred to manufacture a continuous strand which is then cut into standard lengths or according the customer's specifications. The glued joint lies in the neutral zone as regards pressure and tensile stress and does not affect the properties of the board. The lamination provides a final product of higher grade than before and at a far cheaper price than before. It will be appreciated that the method according to the invention can be modified in different ways and that, although but one bottom or support layer is shown in the drawings, several such layers can be provided, if this is desired for specific purposes, in which case the board sections are split in a dif¬ ferent manner that may be more convenient for the specific purpose. Furthermore, it is of course pos¬ sible to add a layer of a different material in the board, for example between the top and bottom layers of the board.