| 摘要 |
PROBLEM TO BE SOLVED: To obtain an excellent working precision while securing a sufficient strength around the rotation center at the tip of the end mill body. SOLUTION: Three arcuate cutting blades 9 in a nearly hemispherical shape, whose rotation track has the center on the axial line O, are circumferentially formed at equal intervals to crossing ridge parts of three gashes 7 and flanks 8 at the tip part of the end mill body 1 rotated around the axial line O. A chisel part 12 is formed by arranging the inner peripheral ends 10, 11 of the gashes 7 and the arcuate cutting blades 9 apart from the rotation center C around the rotation center C on the axial line O at the tip of the end mill body 1. Chisel blades 13, which are continuous to the inner peripheral ends 11 of the arcuate cutting blades 9 and extended each to the rotation center C, are formed to the crossing ridge parts of the circumferentially adjacent flanks 8 each other in the chisel part 12 so as to be substantially along the hemisphere formed by the rotation track of the arcuate cutting blades 9. COPYRIGHT: (C)2005,JPO&NCIPI
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