BE CUT INTO FLOOR BOARDS

The present invention relates to a pattern sheet which has a bar pattern comprising a plurality of parallel rows of bars, the bars in adjoining rows preferably being mutually offset in the longitudinal direction, and which is intended for use in the making of a panel to be cut into floor boards with n + 1 rows of bars having essen- tially the same width, n being 2, 3, 4 ... .

In the making of a laminated floor, use is frequently made of a laminate which consists of a plurality of sheets, such as phenol or melamine impregnated sheets of paper compressed under high pressure, and which is glued to a body,, e.g. a particle board, so as to form a laminat¬ ed board which is subsequently sawn into a number of floor boards.

The laminate comprises a pattern sheet which has been provided with a pattern and which gives the laminate its pattern. A pattern of this type is often modelled on one of nature's materials, such as wood.

A much-used bar pattern consists of a plurality of parallel rows of equally wide, wood-resembling bars, the bars in adjoining rows being mutually offset in the longitudinal direction. A laminated board provided with such a pattern is usually cut into three-bar floor boards, i.e. floor boards with three rows of bars. To this end, the laminated board is sawn along the dividing line between the third and fourth rows, the dividing line between the sixth and seventh rows, etc. Since this sawing operation requires a precision hitherto unattained in actual practice, the resulting floor boards frequently have four instead of three rows of bars, the width of the two outer rows put together equalling the normal width of the bars in said pattern. One of the outer rows often has a width not larger than a few millimetres, which corre-

sponds to the lateral setting error of the saw and which makes the floor board look very unaesthetic.

The object of the present invention is therefore to obviate this inconvenience and provide a pattern sheet which is so constructed that a saw setting error of a few millimetres does not result in a floor board having more rows of bars than desired and, consequently, an unaes¬ thetic appearance.

According to the invention, this object is achieved by means of a pattern sheet of the type described by way of introduction and characterised in that the bar pattern over essentially its entire width is designed in such manner that the bars in every n:th row are substantially twice as wide as the bars in the other rows. Preferably, the bar pattern has, nearest to each side edge, n rows of bars of essentially the same width as the bars in the other rows.

Since the cutting of the panel into floor boards oc¬ curs near to the centre lines of the wider bar rows, only n + 1 rows of bars are obtained in every floor board when the pattern sheet according to the present invention is used, also when the saw setting error is considerable. When the setting error is moderate, the width of the two outer rows cannot be seen to substantially differ from that of the other rows.

The invention will be described in more detail below, reference being had to the accompanying drawing illustrat¬ ing an embodiment of a pattern sheet according to the in¬ vention. The pattern sheet shown in the drawing is a sheet of paper intended for use in the making of a laminate which is obtained by compressing, under high pressure, a plura¬ lity of phenol or melamine impregnated sheets of paper. Then, the laminate is glued to a body, e.g. a particle board, to form a laminated panel which is cut in its lon¬ gitudinal direction into floor boards.

However, it should be observed that the pattern sheet according to the invention must not necessarily be a sheet of paper but may, for example, also be a patterned film or foil which is glued to a body to form a panel which is subsequently cut into floor boards.

Printed on the pattern sheet is a bar pattern which ^' comprises thirteen parallel rows of wood-resembling bars whose wood-like appearance is, however, not shown in the drawing. The bars have the same length (433.3 mm), and the bars in adjoining rows are mutually offset by half a bar length in the longitudinal direction.

The pattern sheet shown is intended for use in the making of a laminated panel to be cut into three-bar floor boards. Therefore, the bars in the third, the fifth, the seventh, the ninth and the eleventh row are substantially twice as wide as the bars in the other rows. The width of the wider bars is preferably slightly larger than the double width of the narrower bars, the difference compen¬ sating for the waste of material occurring at the saw cuts when the laminated panel is cut into three-bar floor boards. The cuts are placed substantially along the longi¬ tudinal centre lines of the broad bar rows, resulting in that the width of the two outer rows in each floor board, when the saw setting error in the lateral direction is moderate, cannot be seen to differ materially from the width of the centre row and therefore does not lend an unaesthetic appearance to the floor board. Even when the saw setting error is considerable, the cutting results in floor boards having three and not four rows of bars. In the embodiment shown in the drawing, the narrower bars of the pattern sheet have, except in the two outer rows, a width of 67.7 mm, while the wider bars have a width of 146.4 mm, i.e. the double width of the narrower bars, plus 11.0 mm. In the outer row to the left, the bars have a width of 74.7 mm, and in the outer row to the right, their width is 78.7 mm. Consequently, the total width of the pattern sheet is 1291.6 mm.

Before the pattern sheet is used, it is cut clean by edging, 6 mm being cut off at each edge. After edging, the bars in the two outer rows thus have a width of 68.7 mm and 72.7 mm, respectively. When the laminated panel.is cut, the saw cuts, which have a width of 5 mm, are not laid exactly on the centre lines of the rows of wider bars, but 2 mm to the right of these lines. In this manner, boards are obtained where the width of the left bar row is 68.7 mm and the width of the right bar row is 72.7 mm. These boards are subsequently worked into tongued and grooved floor boards, a groove being milled in the left board edge and a tongue being milled in the right board edge. In these milling opera¬ tions, the width of the boards is reduced by 1 mm at the groove side (the -side to the left) and 5 mm at the tongue side (the side to the right). Thus, both the left and the right bar rows are given a width of 67.7 mm, i.e. the same width as the centre bar row.

As is obvious to anyone skilled in the art, the ideas described above are, naturally, also applicable to such sheets as are made up of pieces of wood put together to form a bar pattern of the type described above. The term "pattern sheet" as used in the appended claims therefore not only relates to a pattern sheet of the type described above, but also to a sheet made up of pieces of wood.