| 摘要 |
A cylindrical cutting element comprises a substrate 2 provided with a face of ultra hard material 4 at one end. At the interface 3 between the substrate and the ultra hard material is a first concave depression 34 which extends radially outwards from near the centre of the element to the outer edge. A second depression 12, formed on the surface 5 of the ultra hard material 4, also extends radially from near the centre and may be aligned over the first depression 34. The first and second depressions may increase in width and depth as they extend radially outwards. Further depressions may be formed on the interface and the exposed surface of the ultra hard material. In addition, smaller, secondary depressions (38, figures 5 and 6) may be made around the first and second depressions 34 and 12. Transition layers (42, figure 7) may be placed between the substrate and the ultra hard material, having properties intermediate the two, and a circumferential groove (68, figure 9) may be formed in the outer surface of the substrate 2 and filled with additional ultra hard material. |
