Device for Cutting Sheet Material

a. Field of the Invention:

This invention relates to a device for cutting sheet material, such as foils and layers of textile material, by means of a thermal cutting beam, the device having support means for supporting the sheet material to be cut.

B. Prior Art:

It is known to employ a laser beam for cutting material, the action of the laser beam being substantially a torch-cutting effect. The laser beam must, for this purpose, be focussed on the cutting location. As this is done, the laser beam generates a considerable amount of heat not only directly at the level of the cutting location but also in the zones located therebelow. If the material to be cut is a material which is not rigid, for example, a textile material, then it is necessary to lay it on a table. Consequently, the table is subjected to a considerable degree of heating and thermal stress due to the laser beam.

The present invention provides a device for cutting sheet material by means of a thermal cutting beam, including plate-like supporting means having holes therethrough and arranged to support said sheet material.

In order that the invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

FIG. 1 is a perspective view of a device for cutting textile material by means of a laser beam;

FIG. 2 is a sectional view of a perforated table top of the device and one of a plurality of supports on which the table top bears; and

FIG. 3 is a view similar to that of FIG. 2 with certain parts removed.

The device shown in FIG. 1 comprises a table 1 on which a first carriage 2 is arranged to be displaced on rails 3 secured to the table 1. Mounted on the first carriage 2 is a second carriage 4 which is displaceable transversely of the direction of displacement of the first carriage 2. The first carriage 2 is provided for this purpose, with travel rails 5. The first carriage 2 is driven by means of a motor 6. The second carriage 4 is driven by means of a further drive (not shown).

The table 1 includes a plurality of bearer strips 14 from which there is supported (in a manner to be discussed later) a perforated table-top 7 providing plate-like supporting means. The table-top 7 is made from a material which is a good thermal conductor, for example from copper or brass.

A laser beam 10 is generated by means of a laser gun 8 and is radiated, by means of an optical system 9, to a first mirror assembly 11. The first mirror assembly 11 is disposed on the first carriage 2 and reflects the laser beam 10 to a second mirror assembly 12 on the second carriage 4. The second mirror assembly 12 reflects the laser beam 10 into a focussing device 13 which focusses the laser beam 10 at a point located a short distance above the surface of the perforated table-top 7.

Because it is perforated, the table-top 7 is not adversely affected by the heat generated by the laser beam 10, the heat imparted to the webs between the perforations being readily discharged or dissipated to the surroundings.

FIG. 2 shows the manner in which the perforated table-top 7 is supported on the bearer strips 14. For this purpose, there are employed a plurality of supports 15 each being vertically adjustable relative to the associated bearer strip 14 by means of a screw-threaded shank 16 of the support. Disposed on each support 15, which includes an upper part of conical shape, is a cowl 17 having the shape of a hollow cone. The hollow cone-shaped cowl 17 has a projection 18 at its upper end fitted into a perforation of the table-top 7. The cowl 17 and the upper part of each support 15 are also made from a material which is a good thermal conductor, preferably from copper or brass, so as to discharge the heat with which the laser beam 10 heats the table-top 7. By vertical adjustment of the supports 15, it is ensured that the focus of laser beam 10 is always properly disposed with respect to the material to be cut.

Referring to FIG. 3, herein the perforated table-top 7 has been removed, as have been the cowls 17. In this case, it is required to cut a timber panel 18 having sufficient natural rigidity so that the latter can be directly supported on the apices of the conically-shaped upper parts of the supports 15.

The fumes produced by the cutting process are sucked-away downwardly either through the perforated table-top 7 or, in the case of FIG. 3, directly downwardly, by a suction means (not shown) disposed below the table-top 7.