Patent ID: 6077591
Filing Date: 2000-06-20
Classification: B23B,E21B,Y10T

Abstract:
A preform element incuding a facing table of superhard material having a front face, a peripheral surface, and a rear surface bonded to a front surface of a substrate which is less hard than the superhard material, the front surface of the substrate being formed around its periphery with an annular peripheral stepped rebate comprising an inner wall disposed at an angle to the front surface of the substrate and a bottom wall disposed at an angle to the inner wall, the front surface of the substrate being further formed with a plurality of recesses located inwardly adjacent the inner wall of the peripheral rebate and being spaced apart around said inner wall, the rear surface of the superhard facing table being formed with a peripheral rim which extends into the peripheral rebate in the substrate, and a plurality of spaced projections, located inwardly adjacent the peripherial rim, which extend into said recesses in the substate, said recesses in the substrate being curvilinear as they extend inwardly away from the inner wall of the peripheral rebate.