Pinching collet chuck

INTRODUCTION
This document describes the functionality of the collet chuck, and the basic dimensions.  Useful data (unit conversion), materials and complete manufacturing drawings also included in appendix.

MAIN SECTION
These are used mainly for clamping cold-rolled bar or for re-chucking workpieces on a previously machined surface. In design, distinction is made between collet chucks with retractable collets, advancing collets and stationary collets. Collets may perform feeding or clamping functions. A feeding collet is a hardened steel sleeve having slits cut partway along its length and forming flexible jaws whose ends are brought close to each other. The form and size of the hole in a feeding collet must correspond to the work bar profile. A feeding collet is screwed onto the feeding tube, which is advanced, by a cam-type or an air-mechanic actuator, thereby feeding the bar placed inside it. When loaded on the machine, the bar is pushed through the jaws of the feeding collet. The jaws are pressed by elastic force against the bar surface. As the feeding tube is advanced, the jaws of the feeding collet close under the action of friction forces, and clamp the bar.