| 摘要 |
A preform cutting element 10, for a rotary drill bit, includes a layer 12 of polycrystalline diamond material having a front cutting face 15, a rear face 16 and a peripheral surface 17, a cutting edge 18 being provided by at least part of the junction between the front cutting face and the peripheral surface. The diamond layer is formed around its periphery, adjacent the cutting edge, with a row of spaced apertures. Each aperture is in the form of a bore 19, formed for example by a laser, which is inclined at 45.degree.to the cutting face 15 and extends completely through the diamond layer from the cutting face 15 to the peripheral surface 17 thereof. The apertures serve to inhibit the propagation of spalling across the cutting face from the cutting edge. |
