| 摘要 |
PROBLEM TO BE SOLVED: To provide a throwaway tip 1 for a drill of one tip type with two similar tips having an inner blade 11 cutting a center portion of a hole and an outer blade 12 cutting a circumferential edge of the hole which are arranged across the drilling hole at a tip in which the strength is higher and the durability is more excellent. SOLUTION: In the tip 1, the thickness T1 on an inner blade 11 side having a first face 13a and a first bearing surface 1b is set to be smaller than the thickness Te2 on an outer blade 12 side having a second face 14a and a second bearing surface 1c.
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