| 摘要 |
PURPOSE:To prevent the occurrence of an exit burr at the passing through edge of a hole, improve the life of a cutting edge and make regrinding possible by forming the drill by specifying a point angle formed by the two cutting edges and brazing a superhigh pressure sintered body on the flank of the cutting edge. CONSTITUTION:A point angle formed by two cutting edges 35 at the tip of a tool body 33 is formed in an angle from 35 deg. to 40 deg., and a drill flank is formed of a superhigh pressure sintered body made of diamond from a chisel part at a tool tip to an end on the outer peripheral side of the tool and to the depth of about 0.7mm from a flank surface, and the above-mentioned superhigh pressure sintered body is fixed on the tool body 33 by brazing. Thus, in this drill 31, the point angle restricted as mentioned above can prevent the occurrence of an exit burr at the passing through edge of hole, and the superhigh pressure sintered body formed on the flank surface can improve the life of the cutting edge 35, and moreover its formation extending over the whole flank surface and having the above-prescribed depth can simplify drill regrinding work, and apply the cutting edge again to a machining process.
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