| 摘要 |
A preform element, for example for use as a cutting element on a rotary drag-type drill bit, includes a facing table (28) of superhard material having a front face and a rear face bonded to the front face of a substrate (29) which is less hard than the superhard material. The rear face of the facing table comprises a surface formed with a plurality of spaced protuberances (31) and a plurality of spaced sockets (32), and the front face of the substrate comprises a surface which is bonded to the surface of the facing table and is formed with a plurality of spaced protuberances (34) which are bonded within said sockets (32) in the facing table, and a plurality of spaced sockets (35) within which are bonded said protuberances (31)on the facing table. <IMAGE> |
