| 摘要 |
PROBLEM TO BE SOLVED: To provide a chuck of favorable tightening precision and torque transmitting performance. SOLUTION: A tightening device has a tightening sleeve 3 journalled in a tapered centering opening 14 in a casing body 2. For tightening and releasing the tightening sleeve 3, a chuck pinion 17a to which a rotary body 20 belongs is utilized. This has a center opening 23 provided with female threads or male threads, and this is directly engaged with the tightening sleeve 3. The rotary body 20 is supported by a corresponding shaft bearing surface to the casing body 2, preferably through a rolling bearing. The rotary body 20 is driven through a reduction drive such as a worm. High tightening force can thus be generated based on relation between a relatively small diameter of a tightening screw and a small taper angle. The small diameter of the tightening screw assures small screw friction. |
