| 摘要 |
A drill blade for a drill bit intended to be used to bore holes in the roofs of mines is made of hardened tungsten carbide. The blade has two end sections, one on each side of a central section, and the end sections have a higher degree of hardness than the hardness of the central section. Also, the central portion of the blade is made thicker than the distance between the planar surfaces of the end portions thereof such that the blade has a central protrusion and will be self centered on a slot in the bit body having a recess adapted to receive the central protrusion.
|
