| 摘要 |
PROBLEM TO BE SOLVED: To improve dischargeability of chips generated by a bottom blade adjacent to a long bottom blade on its rear side in a rotating direction of an end mill.SOLUTION: Bottom blades 9 are formed on crossing ridge line parts of gashes 7 and tip flank surfaces 8 of tips of a plurality of chip discharge grooves 4 formed on an end mill body 1, and at least one blade among the bottom blades 9 is a long bottom blade 9A extending longer to an inner peripheral side than other bottom blades 9B and 9C. In the end mill body 1, each of coolant holes 10 is formed between the chip discharge grooves 4, and an interval in a tip view in an axis O direction between the long bottom blade 9A and an aperture part of a first coolant hole 10A thereof open to a rear side in a rotating direction T of an end mill is configured to be larger than an interval in a tip view in the axis O direction between the second bottom blade 9B adjacent to the long bottom blade 9A on its rear side in the rotating direction T of the end mill and an aperture part of a second coolant hole 10B thereof open to the rear side in the rotating direction T of the end mill. |
