WO2000053860A1

WO2000053860A1 - A gypsum board and a method for its manufacture

Info

Publication number: WO2000053860A1
Application number: PCT/IB2000/000250
Authority: WO
Inventors: Christer Klasson
Original assignee: Bpb Plc
Priority date: 1999-03-10
Filing date: 2000-03-07
Publication date: 2000-09-14
Also published as: SE9900848D0; SE9900848L

Abstract

A gypsum board (1) has at its two longitudinal edges sloping rims (2) at one of its side surfaces. The board is provided with a recess (3) halfway between its edges for enabling the board to be divided into two boards (1A, 1B).

Description

A GYPSUM BOARD AND A METHOD FOR ITS MANUFACTURE

Technical Field

The present invention relates to a gypsum board provided at its two longitudinal edges with sloping rims at one of its side surfaces. It also relates to a method for its manufacture.

Background of the Invention

Gypsum boards are widely used in the building industry, for example for forming interior walls by being attached to studs of a framework. When the longitudinal edges are laid together, a grooved joint is formed by the sloping rims. This joint is often provided with a tape and filled with filler, which may be smoothened for forming a plane substrate for paint or wall paper.

A common gypsum board, which is provided with protective and binding plasterboard paper on both sides, can have a thickness of between 6 mm and 25 mm, for example 12.5 mm, and a width of 1200 mm, whereas its length may vary between 2200 mm and 3600 mm, depending on the intended use . The width is chosen as twice the standard distance between neighboring vertical studs, said distance being 600 mm, which means that the board may be manually handled and covers a relatively large area. When a smaller area is to be covered, the board has to be divided, which among other things can lead to difficulties with regard to joining, as at least one side of the joint may not have the sloping rims .

Even if a board with the standard width of 1200 mm may be manually handled, ergonomical problems for the workers may arise due to the size and weight, and it may be advantageous to supply narrower boards . A board with a width of 900 mm is being supplied to the market, but a drawback at the manufacture is that the capacity of the manufacturing line built for a width of 1200 mm is only used to 75%.

Another possibility would be to manufacture gypsum boards with a width of 600 mm. It has, however, proven difficult to manufacture two such boards in parallel on the 1200 mm manufacturing line with retained quality and tolerances with regard to board dimensions and the shape of the sloping rims. The Invention

A solution to the above problem is according to the invention that the board between its edges is provided with at least one longitudinal recess with sloping sides, preferably one recess halfway between its edges. This means that the board with for example a width of 1200 mm rather easily may be divided into two boards, each with a width of for example 600 mm and with the same possibility to form a joint as a normal board.

This wide board may already at the manufacturing be divided by for example sawing or waterjet cutting into two narrower boards. In this case it is possible to glue protective tapes over the sawn edges. Alternatively, the wide board (1200 mm) may be delivered with the central recess and, if desirable, be divided at the mounting place. Brief Description of the Drawing

The invention will be described in further detail below under reference to the accompanying drawing, in which Fig 1 shows a gypsum board according to the invention in a perspective view and Fig 2 is an end view of a modified left part of the board of Fig 1.

Detailed Description of a Preferred Embodiment As is well known in the art, a gypsum board 1 has a core of gypsum or calcium sulphate covered by plasterboard paper at each side surface. Normally, this paper extends over the longitudinal edges of the board but not over its transverse ends .

A board may have a thickness of 12.5 mm (although thicknesses between 6 mm and 25 mm occur) and a width of 1200 mm, i e twice the standardized distance between neighboring vertical studs in a wooden framework or the like of a building.

The board 1 has sloping longitudinal rims 2 at one of its side surfaces, whereas the opposite surface normally is plane . When two boards 1 are placed next to each other and are attached to the framework, the formed groove-shaped joint can be provided with a tape and filled with filler, which may be smoothened for forming - together with the board - a plane surface for constituting a good substrate for paint or wallpaper.

According to the invention the board 1 has a central longitudinal recess 3 with slopes corresponding to or different from the sloping rims 2. At this recess 3 the board 1 may be divided into two narrower boards 1A and IB, in the described case each with a width of 600 mm, suitable for covering the distance between two neighboring studs in the framework.

Placed against the edge of another board 1 this divided board 1A or IB may provide an equally good joint as one between two boards .

The division of the board is normally performed by a sawing or waterjet cutting machine in the gypsum board factory. However, it is also possible to deliver the recessed board 1 and to perform the possible division along the recess 3 by means of a suitable tool, such as a knife, followed by a manual breaking of the board into two halves .

When the division is performed in the factory, the width of the full width board may be 1200 mm with the addition of the width for the saw cut, so that each of the resulting two narrower boards has a width of 600 mm.

As is illustrated in Fig 2, a protective tape 4 may be glued over the sawn edge of the divided board, especially if the division has been performed in the factory and the divided boards 1A and IB are then transported and handled. This tape facilitates joint treatment .

A gypsum board can according to the invention be provided with more than one longitudinal recess 3 for giving narrower boards with different widths, but normally one recess halfway between its edges is provided.

Claims

1. A gypsum board provided at its two longitudinal edges with sloping rims (2) at one of its side surfaces, c h a r a c t e r i z e d in that the board (1) between its edges is provided with at least one longitudinal recess (3) with sloping sides.

2. A gypsum board according to claim 1, c h a r a ct e r i z e d in that the board (1) is provided with one recess (3) halfway between its edges.

3. A gypsum board according to claim 1, c h a r a ct e r i z e d in that the board is provided with more than one recess (3) .

4. A method of manufacturing a gypsum board provided at its two longitudinal edges with sloping rims at one of its side surfaces, c h a r a c t e r i z e d in that the board (1) is manufactured in a certain full width for which the manufacturing line is built and at the manufacture is provided between its edges with a longitudinal recess (3) with sloping sides and is then divided into two narrower boards (1A, IB) .

5. A method according to claim 4, c h a r a c t e ri z e d in that the division is performed by means of a sawing machine.

6. A method according to claim 4, c h a r a c t e r- i z e d in that the division is performed by means of a waterjet cutting machine.

7. A method according to claim 5 or 6, c h a r a ct e r i z e d in that a protective tape (4) is glued to the sawn or cut edge .

8. A method according to claim 5 or 6, c h a r a ct e r i z e d in that the full width board (1) has a width of 1200 mm, with the possible addition of the width of the cut, and the narrower boards (1A, IB) 600 mm each.