| 摘要 |
<p>S P E C I F I C A T I O N "improvements in or relating to rotary drill bits" The body of a rotary drill bit is formed from a matrix formed by a powder metallurgy process, and a plurality of cutting elements are mounted on the bit body, each cutting element being in the form of a disc of super hard material which is thermally stable at the temperature of formation of the matrix. The front surface of each cutting element is engaged by a holding structure on the bit body in front of the cutting element, the arrangement of the holding structure being such that the resistance provided by the holding structure to forward deflection of the portion of the cutting element opposite the cutting edge is less than the resistance to rearward deflection provided by the surface behind the cutting edge. Bending stresses imparted to the cutting element by rearward deflection thereof in the vicinity of the cutting edge are thereby reduced.</p> |
