| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To smoothly discharge cutting chips generated by a long bottom blade extending near the axial line of an end mill body tip without jamming of the chips. <P>SOLUTION: In this ball end mill, a plurality of bottom blades 7 having a semi-spherical rotary trajectory around an axial line O are formed at a tip of an end mill body 1 rotating around the axial line O, and a plurality of outer peripheral blades 7 communicated to an outer end of the bottom blade 5 are formed on an outer periphery of the end mill body 1. Some of the bottom blades 7A are long bottom blades 7A extending near the axial line O at the tip of the end mill body 1. A narrow angleθformed by two straight lines C, D connecting the axial line O to two outer peripheral blades 5A, 5B communicated to the long bottom blades 7A and bottom blades 7B positioned in an end mill rotary direction T on a cross section orthogonal to the axial line O is made larger than a narrow angleθformed by a tangent A at an inner end 7a of the long bottom blade 7A seen from the tip in the direction of the axial line O and a tangent B at an inner end 7b of the bottom blade 7B positioned in the end mill rotary direction T of the long bottom blade 7A. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
