| 摘要 |
<p>The element (1) has a cylindrical shape and a slightly conical inner surface provided with several axially positioned recesses (5). The recesses (5) are wider at the front, joined with edges (7) of a convex, concave, or corrugated shape and provided with lubricant transferred into a liquid state when heated above a threshold temperature. The rear segment (4.2) of the drill head is of a cylindrical shape (4) and joined to a carrying element with recesses complementary to the recesses (5) at the head (1) located at the insertion area.</p> |
