| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rock drill wherein when it is brought in contact with a reinforcing bar, the risk of damaging a head made totally of a hard material is reduced and its life is elongated. SOLUTION: In the rock drill for the hand tool equipped with the head made totally of the hard material (1) which has one main cutter (2) and at least one auxiliary cutter (3a, 3b) arranged exclusivly within an outside area in a radial direction, a subsidiary edge tip is arranged by being extended in an arcuated state.
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