| 摘要 |
PURPOSE:To obtain a throw-away type drill having an abrasion resistance, an agglutination resistance, and a sufficient toughness at a low cost by forming a blade part of a sintered body of alumina reinforced by silicon carbide whiskers, and jointing it mechanically with a shank part composed of steel. CONSTITUTION:A blade part 31 is composed of an alumina sintered body including silicone carbide whiskers of an aspect ratio of 3-200 by 3.0-40volume% for giving an abrasion resistance and an agglutination resistance, and a shank part 32 is composed of steel for giving a breakage resistance. For jointing the blade part 31 with the shank part 32, the blade part 31 is fixed to the shank part 32 by friction force generated by application of a side part of a held part 31a of the blade part 31 to inner end surfaces of holding parts 33a, 33b of the shank part 32, for example. Otherwise, they may be fixed by use of a tip threaded at an outer circumferential part and an inner circumferential part of a forward end of the shank part respectively, or they may be fixed by the blade part of a single blade type engaged with the shank part and fixed by a screw. |
