| 摘要 |
A rotatable tool for breaking hard material includes an elongated tool body and a cutting cap mounted on the tool body. The cutting cap includes a generally conical front tip having a maximum first diameter (d), and a rear base portion having an outer peripheral surface defining a maximum second diameter (D). An intermediate portion extends from the tip to the base, and at least a part of the intermediate portion has a concave outer peripheral surface. A longitudinal extent (H) of the cap extends from a front end of the tip to a rear end of the outer peripheral surface of the base. A ratio of d to D is equal to or greater than 0.7. A ratio of H to D is equal to or greater than 1.0.
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