| 摘要 |
A hollow drill is provided to raise the sintering temperature of the hollow drill from 840°C to 920°C or above by using a press mold made of graphite. A hollow drill comprises a support member and at least one cutting element. The cutting element has a cutting edge(20) protruding in a forward direction of the cutting element. The cutting element is disposed at an end of the support member or inserted into the supporting member. Grinding surfaces(21) are formed adjacent to both sides of the cutting edge. Each grinding surface includes a first region(24) having an inclination angle of 90 degrees or above relative to the forward direction of the cutting element and a second region(25) having an inclination angle smaller than the inclination angle of the first region.
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