| 摘要 |
<p>A drill apparatus comprises a tool joint(l); at least one undercut(4), which is on the surface of the thicker and wider section of the tool joint(l), and the undercut's longitudinal axis is parallel to the axis of the tool joint(l), at least one insert(2), which can be inserted into and removed from the undercut(4), the insert(2) can be securely retained by the undercut(4). A method of making the tool joint of a drill apparatus comprises the following steps: at least one undercut(4) is cut on the surface of the thicker and wider section of the tool joint(l), and the undercut's longitudinal axis is parallel to the axis of the tool joint(l).</p> |
