| 摘要 |
PROBLEM TO BE SOLVED: To provide a core bit capable of forming a shape for easily drawing the bit from a material to be cut in the case that a reinforcing bar piece or gravel is bitten in a gap between the bit and a core at the time of using the bit and preventing an abrupt wear of a specific tip. SOLUTION: Notches are provided at two adjacent tips of tips 1 of the core bit. The notches are provided at parts adjacent to a gap of the two tips 1b, 1c so that the radial inner surfaces of the notches and inner surfaces of the tips are in plane. If a reinforcing bar piece or gravel is bitten in a gap between the bit and a core, the bit is manually rotated to bite an axially extended part of the bit with the notch of the tip 1, and the bitten tip is brought so that the bit can be easily drawn from a material to be cut.
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