A CUTTING TOOL, PARTICULARLY FOR STONE MATERIALS AND

THE LIKE

Technical field

The present invention relates to a cutting tool for stone materials, porcellaneous stoneware, glass and other materials, having the characteristics listed in the preamble of the main Claim 1. Technological background

The invention is particularly applicable to the field of cutting where use is made of tools such as rotating discs provided with abrasive segments, typically formed from diamond powders mixed with binders such as powdered metals or the like.

The invention is particularly intended for use with cutting discs, although the essential inventive concepts of the invention can also be applied to cutting tools of the blade type. In this field, there are known technical solutions which provide cutting edges of tools having a plurality of abrasive segments spaced at angular intervals, with a transverse thickness greater than the thickness of the support, to enable the segment to penetrate into the material to be cut, without any interference with the support to which the segments are attached.

There are also known solutions which provide repeated sequences of abrasive segments projecting along the cutting edge, in which the segments in the sequence have different heights and/or widths, which may for example increase or decrease in the direction in which the tool cuts, this configuration providing a greater penetrating capacity and a greater ease

of expulsion and discharge of the dust of abraded material formed in the cutting operation.

In this field, in the case of certain materials such as glazed porcellaneous stoneware tiles, it has been found necessary to achieve a suitable quality of surface finish during the cutting operation itself, especially on the surfaces abraded by the tool during cutting and along the edges adjacent to the cut. Disclosure of the invention

A principal object of the invention is to provide a cutting tool capable of meeting the aforesaid requirements while overcoming the limitations of the known solutions.

This object and others which are described more fully below are achieved by the invention by means of a cutting tool made in accordance with the claims below.

Brief description of the drawings Other features and advantages of the invention will become clear from the following detailed description of a preferred example of embodiment thereof, illustrated, for the purpose of illustration and in a non-limiting way, in the attached drawings, in which :

Figure 1 is a perspective view of a cutting tool made according to the invention;

Figure 2 is a partial view on an enlarged scale of a detail of the tool of the preceding figures;

Figure 3 is a view corresponding to that of Figure 2, in a variant embodiment of the invention; - Figures 4 and 5 are views corresponding to that of Figure 2, of

corresponding additional variant embodiments of the invention. Preferred embodiment of the invention

With reference to Figure 1 initially, the number 1 indicates the whole of a cutting tool made according to the present invention. The tool 1 is shaped in the form of a cutting disc and comprises an axially symmetrical disc-shaped support 2, having a principal axis indicated by X in the drawings, and carrying a circumferential edge 3, to which abrasive cutting segments are attached. The number 4 indicates the transverse thickness of the disc at the edge 3, measured parallel to the axis X.

The support 2 is designed with a central hole 6 for attachment to a drive shaft (not shown) intended to cause the disc to rotate in cutting operations, the direction of cutting being positioned tangentially to the circumferential edge 3. The tool 1 also comprises a first and a second plurality of abrasive segments, the segments of each plurality being indicated by 8 and 9 respectively, these segments being attached to the support at the edge 3 and projecting radially from the support, in a predetermined configuration providing a repetition of sequences in which segments 8 alternate with segments 9.

In a preferred configuration (Fig. 2), the sequence repeated along the edge 3 comprises a pair of segments 8, adjacent to a pair of segments 9, all the segments being aligned circumferentially along the edge 3. It is also specified that the aforesaid sequence is repeated with a constant angular interval along the edge, as is clearly shown in Figure 2.

Alternatively, it is possible to provide a sequence comprising a segment 8 adjacent to a segment 9, the said segments being aligned circumferentially along the edge (Fig. 3), or, as a further alternative, it is possible to provide a sequence in which a pair of segments 8 or 9 is placed adjacent to a single segment 9 or 8 (Figures 4 and 5). Figures 2 to 5 show the sequences described above, although it is to be understood that other configurations of sequences of segments 8 and 9 are possible, according to the specific requirements encountered in the cutting of certain materials. Returning to the configuration of Figure 2, according to a principal characteristic of the invention, it is specified that the thickness of the segments 8, indicated by 8a, is greater than the thickness 9a of the segments 9, both of these values being measured parallel to the principal axis X. It is also specified that the material selected for making the segments 8 of the first plurality has a smaller particle size than that of the material from which the segments 9 of the second plurality are formed. In this case, it is specified that the abrasive material of each segment is formed from a mixture of an abrasive material and a binder, the aforementioned particle size relating to the abrasive material only (in most cases, the abrasive material used is industrial diamond). A preferable option is to make the thickness 8a of the segments 8 a few tenths of a millimetre (for example, about 0.1 mm) greater than the thickness 9a of the segments 9.

Each abrasive segment 8, 9 is preferably made by a sintering process and is fixed to the support 2 by welding, particularly by braze welding or laser welding.

Because of the aforementioned features, the segments 9 are primarily required to carry out the actual cutting function, and are therefore conveniently formed from materials having a larger particle size, for greater cutting efficiency, while the segments 8, having a greater thickness and smaller particle size, are primarily required to carry out the surface finishing function during the cutting operation. Consequently the two functions are integrated and carried out during the operation of cutting the material, thus efficiently providing the aforementioned dual action. It has been found that this effect of improved surface finishing obtained simultaneously with the cutting operation is particularly desirable in the cutting of stone materials or glazed porcellaneous stoneware, where it is important to avoid invasive fractures of the glaze while still limiting the processing time, which in turn requires the use of very large diamond particle sizes (the particle size of the diamond used in the segments is increased in order to increase the cutting power of the tool).

Thus the invention achieves the proposed objects while yielding the aforementioned advantages by comparison with the known solutions.