| 摘要 |
<p>A self-tightening drill chuck includes a drill chuck main body, three collet jaws, a pushing threaded rod and a pushing nut. A spiral groove having an arc-shaped cross-section is machined on the outer surface of the pushing threaded rod, and at least three through holes are machined along the radial direction on the pushing nut at a position opposite to the spiral groove on the outer surface of the pushing threaded rod. One steel ball and one lock-pin preventing the steel ball from falling off are positioned in each through hole. One part of the steel ball is set in said spiral groove, and another part of the steel ball is set in said through hole. The pushing nut is rotably jointed on the pushing threaded rod via said steel ball, thus the friction force between the pushing threaded rod and the pushing nut is decreased in order to prevent them from locking.</p> |
