Two-piece concentric collet

A collet adapted to be slidably mounted on a tapered outer surface of a nosepiece for being elastically outwardly expanded into clamping engagement with a wall of a hole in which said collet is disposed;

• said collet comprising a rear displacement part and a separate elastically yieldable front clamping part connected to said displacement part;
• said clamping and displacement parts together forming a contact interface extending substantially 360 degrees about a longitudinal center axis of said clamping part for transmitting rearward forces from said displacement part to said clamping part.

A collet adapted to be slidably mounted on a tapered outer surface of a nosepiece for being elastically outwardly expanded into clamping engagement with a wall of a hole in which said collet is disposed;

• said collet comprising a rear displacement part and a separate elastically yieldable front clamping part connected to said displacement part;
• said clamping and displacement parts together forming contact interfaces for transmitting a rearward and forward forces, respectively, from said displacement part to said clamping part, there being provided longitudinal play between said clamping and displacement parts, enabling said displacement part to move longitudinally forwardly relative to said clamping part and apply a radially inward force to said clamping part during initial forward movement of said displacement part.

A clamping unit adapted to be mounted on a drilling device for clamping the drilling device within a hole of a fixture;

• said clamping unit comprising a hollow nosepiece having a tapered outer surface, a hollow collet mounted on said outer surface and including a front elastic clamping portion and a rear displacement portion;
• and a displacement mechanism connected to the displacement portion for displacing the collet rearwardly along the nosepiece such that the clamping portion is elastically expanded outwardly into clamping contact with said wall of said fixture hole, and forwardly along the nosepiece to enable the clamping portion to spring back to a rest state;
• the improvement wherein said displacement portion and clamping portion constitute separate parts interconnected to one another and together forming a contact interface extending substantially 360 degrees about a longitudinal center axis of said clamping part for transmitting rearward forces from said displacement part to said clamping part.