| 摘要 |
PURPOSE:To enhance the effective shock withstandability, economy and the dimensional limitation of the sintered material by limiting the high hardness sintered material to the edge portion having the real working diameter and the front tiny portion while employing the super hard alloy or steel at the other portion. CONSTITUTION:The high hardness sintered material 1 is composed of a high hardness sintered material portion 1a and a super hard alloy portion 1b and brazed at the part 1b to the steel or super hard alloy portion 5. The portion of the high hardness sintered member 1 stretching to the biting portion 3 is limited to the small portion in front of the portion C transferring from the biting portion 3 to the portion having the real working diameter, and since all edges will contact with the prebored hole, the intermittent contact of the high hardness sintered member 1 is prevented while since the breaking withstandability is low, the breakdown of the edge is limited to the minimum. Since the substantial working is not required on the guide section 4, the steel or the super hard alloy is sufficiently endurable for the structure. |
