The Area of the Invention

The present invention relates to a method for cutting board, in particular gypsum board.

The invention also relates a device for cutting of board, in particular in connection with the said method.

Prior art

In connection with the cutting of board, in particular gypsum board, two saw blades are generally used for each board in so-called coarse cutting. In order to meet a satisfactory output rate in the production of a length of board it is necessary that coarse cutting as stated is done at high speed, which entails the disadvantage that the noise level will become fairly high. Furthermore coarse cutting as stated will also entail that the cut edges will need subsequently to be cut fine in order that it may be possible to guarantee a 90° cut and sufficiently smooth edges in the board elements when ready cut.

The objectives of the invention

It is the aim of the present invention to provide a method and a device for cutting board, in particular gypsum board, in which the cutting can take place at a lower speed, where the cut made is approximately 90° to the lengthwise direction, while at the same time the cut obtains a sufficiently fine finishing to make further processing unnecessary.

It is a further objective of the present invention to provide a new technique in which the noise level during cutting may be reduced substantially, while at the same

time the new technique leaves less waste in that the need for subsequent fine cutting is obviated.

It is a further objective of the present invention to provide a technique which can be applied to a long board which will only to a very small extent be subjected to any torsion during the cutting process.

It is a further objective of the invention to provide a technique which can be readily adapted to a suitable exhaust system which will also contribute to a more environmentally friendly workplace.

Summary of the invention

The above mentioned objectives are achieved in a method of the nature described initially and characterised by the attached patent claims 1 - 9. A device according to the invention is characterised by the attached patent claims 10 - 18.

Additional features and advantages of the present invention will be evident from the description below as seen in conjunction with the attached drawings, and also from the attached patent claims.

Brief discussion of the drawings

Figure 1 is a sideways sketch showing the major components of a cutting installation in which the method and the device according to the invention may be realised.

Figure 2 is a sideways sketch on a larger scale of a section of the installation as shown in Figure l, comprising additional elements.

Figure 3 is an end-on sketch of the installation as shown in Figure 1.

Figure 4 is a sketch looking in the direction of the arrows IV-IV in Figure 1.

In connection with the present invention and device for cutting board, in particular gypsum board, there will be provided a raw length which is cut into large lengths of board subsequently to be cut into at least two or more standard finished lengths. Shown in Figure 1 and Figure 2 is one part of such a raw length 1, which is here cut into a larger length of board 2, the said length of board 2 having been placed on a base 3 comprising a plurality of platens or belts 4 which are appropriately communicating with a driving means 5 at one end of the base 3.

it should be understood that the said length of board 2 which has been cut from a raw length, may have been dried in advance to a consistency which will allow cutting to be done, and it shall furthermore be understood that the length of board 2 may be brought onto the base 3 either in the lengthwise or the sideways direction.

The length of board 2 of suitable dryness will then according to the present invention be multi-cut across by means of an initial set of pre-adjusted cutting means 6n set at selectable intervals to each other of Ll, L2

Lm corresponding to an initial set of finished lengths. The said initial set of cutting means 6n, as is shown clearly in Figure 4, is part of a device 7 comprising at least one additional set of pre-adjustable cutting means 8n, see Figure 4, which acts as a back-up set or will come into effect when other sets of finished lengths Ll ... Lm are to be cut.

From Figure 1 and Figure 2 it will be seen that the said device 7 which supports the first set of pre-adjusted cutting means 6n, and the additional set of pre-adjustable cutting means 8n, may comprise a rotatable, elongated supporting means 9, e.g. designed as a hollow pipe, or such

like, extending along the whole length of what is relevant to the larger lengths of board 2. At its ends, see especially Figure 3, the pipe shaped supporting means 9 is provided with e.g. a hydraulically driven rotating means 10 which serves to rotate the actual device 7, e.g. 90°, so that either the initial set of cutting means 6n, or the additional set of cutting means 8n, may come to have an effect in the area of the said length of board 2.

In the embodiment shown in Figures 1-4, see especially

Figure 4 , the initial set of cutting means 6n is arranged on a first line along or in parallel with a common rotation axis 11 of the said device 7 , while at the same time the at least one additional set of cutting means 8n is arranged on a second line or in parallel with the said rotation axis 11 of the device, yet at a rotation angle distance α chosen here to be 45°, which, however, may naturally be varied within a wide range, e.g. between 30° and 60°.

In other words the device 7 is arranged so that according to the invention it may comprise a plurality of sets of cutting means, preferably arranged each on its own line along and at intervals around a rotation axis.

In the embodiment shown in Figure 4, the pipe shaped rotatable supporting means 9 is provided with sets of means I2n, lengthwise adjustable, supporting cutting blades, the said means being glidingly adjustable along the said supporting means in order that they may be adjusted lengthwise at the said intervals Ll, L2 ... Lm between the respective cutting blades 6n and 8n, corresponding to the standard lengths to be cut, e.g. 2.40 m or 2.50 ra, or other suitable "standard" lengths.

In Figures 2 and 4 it is shown that the pipe shaped supporting means 9 is connected to a means 13a for exhaust of cutting dust during cutting. Appropriately one further means 13b for exhaust as stated may be connected to a

carriage 14 for movable exhaus , as well as to suitable locking means 15.

In the embodiment shown the device comprises the following main features:

The cutting unit consisting of a pipe supported at either end, and surrounding the pipe there is an enforcement frame.

The pipe being supported, can rotate. - The saws are mounted at an angle of 90°.

The saws being mounted on the pipe may be moved individually in the lengthwise direction of the pipe.

The move may be done manually or automatically.

The saw pipe is also used as a shared exhaust from the saws.

Below the sawing table there is exhaust which follows the saws when the board width is selected.

Appropriately each of the cutting blades may be implemented as substantially circular main saw blades, and even more appropriately each saw blade may on each side be implemented with an additional blade which will, when the respective length of board is intersected by the main saw blade, chamfer off the cutting edges simultaneously with the said intersection.

It was mentioned earlier that the larger length of board 2 may be guided sideways towards the cutting table or the base 3, and the said sideways guiding may appropriately be done by means of transverse belts comprising at least two separate drives, preferably one master drive driving an initial number of drive belts, and a slave drive driving the remaining belts.

A slave drive as stated may appropriately communicate with means sensing an inclined position so that when the means sense an inclined position of the guiding edge of the board relative to references given, the slave drive will over or

under synchronise its drive relative to the master drive, to correct the said inclined position, i.e. perform a 90° check, respectively a diagonal check for precise cutting with the correct result.

.After either the initial set of cutting means 6n or the additional set of cutting means 8n has performed the pre- adjusted cutting, it is appropriate that the cutting means communicate with adjoining collecting table(s) for cut boards of standard length, the collecting table (s) com ^¬ prising subdivided belt sections with individually rever ^¬ sible drives, for transporting the cut boards in either one or two directions. The two directions may then suitably depend on sections given a suitable standard length for subsequent stacking of identical lengths.

These are the benefits achieved in the embodiment shown: Short conversion times between different series of products. Conversion times are reduced because the operator can adjust the saws not in use for the next production line during operation. For the next size in production, the saw pipe is rotated so the the new saws with adjusted lengths turn downwards. - When large series are run, the extra saws may be used as replacement / back-up. Large capacity for cutting boards.

Maintenance may be carried out on the saws not in use, a preventive maintenance which reduces the number of times operations are interrupted.

Few rejects because of the length of the boards which may be run through the saw (fewer fine cut operations of boards) .