| 摘要 |
PROBLEM TO BE SOLVED: To provide a drill head for drilling a deep hole including three, outer, inner and medium cutting blades, achieving high machining accuracy without hindrance even if the end face of work material to be drilled is non-flat due to a center hole, and hardly causing chipping of the blade edge to lengthen the life of the whole head. SOLUTION: The front end 10a of a head body 10 is fitted with inner and outer cutting blades 2A, 2B and an intermediate cutting blade 2C, and a guide pad 3A is fitted to an applied region of cutting reaction force by the inner and outer cutting blades 2A, 2B on the outer periphery of the head body 10. The respective cutting blades 2A to 2C are so arranged that firstly the outer cutting blade 2A, subsequently the inner cutting blade 2B, and lastly the intermediate cutting blade 2C start cutting against a flat work surface. COPYRIGHT: (C)2007,JPO&INPIT
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