T&n Technology Limited

Derek J Dawson

A tool (14,15) for use in working a surface of a non-metallic material having a Vickers hardness value up to 5000 is made up of a layer of platelets (28). The platelets form a working surface (20,21) which is complementary to the required shape. The platelets (28) adjoin one another and present a substantially continuous surface. Each platelet is made of a composite material having a composition comprising silicon carbide, and a material selected from the group comprising gemstone powder, and synthetic diamond powder.

Tools for working non-metallic hard materials

In one method of cross-grinding in accordance with the present invention a non-planar surface on a workpiece, of a non-metallic material having a Vickers hardness value up to 5000, comprises, in each of two grinding steps, traversing the rotational axis of a grinding wheel along a predetermined axis, relative to the workpiece surface. In the first step the radially extending plane of the grinding wheel includes the predetermined axis, and the required workpiece surface is produced with inevitable ridges. For the second grinding step the working surface of the same, or different, grinding wheel is shaped by a tool capable of shaping in a normal manner the working surface suitable for the first grinding step. However, the working surface of the grinding wheel is altered by the radially extending plane of the wheel when presented to the tool being inclined in one sense at a selected angle, in the range 1.degree. to 20.degree., to the direction of this plane if presented to the tool to obtain the shape suitable for the first grinding step. In the second grinding step the ridges on the workpiece are reduced by the radially extending plane of the wheel with said altered working surface being inclined in said one sense at the selected angle to the orientation of the radially extending plane of the grinding wheel in the first grinding step.

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Bradford, United Kingdom

Derek J Dawson