Patent GB-612380-A (GB)
Title: Chuck release mechanism
IPC: B23B31/12
Filed: 1946-05-23
Abstract: 612,380. Chucks. NEWTON, E. P. (Jacobs Manufacturing Co.). May 23, 1946, No. 15686. [Class 83 (iii)] In a chuck having means for moving a gripping member into engagement with a tool and in which resistance to the rotation of the tool actuates the means to tighten the gripping member, a release mechanism is provided comprising a rotatable shock sleeve spring biassed in the driving direction and means for limiting the rotation of the sleeve in one direction so arranged that the sleeve may be rotated against the action of the spring and the spring may return the sleeve and impart a hammer blow between inter-engaging parts of the chuck and sleeve. Two embodiments of the invention are described. In the first, a hollow sleeve 10, Fig. 1, is threaded internally at 11 for attachment to a machine tool spindle and externally at 16 to engage the body 20. Within the sleeve is a hardened steel ball 12 seated on an inclined annular shoulder 13. A bore 14 receives a boss 37 on an abutment disc 35 whose front surface 36 abuts the rear edges of collet gripping members 41 interconnected by a body 42 of resilient material tending to open the collet. The collet is mounted in a member 30 in threaded engagement with the body and provided with flat surfaces 32 to receive a wrench. On a cylindrical part 22 of the body is mounted the shock sleeve 50 having a recess 53 to correspond with a recess 23 in the body forming a pocket 54 housing a spring 60 having one end anchored in the body and the other in the shock sleeve and tending to rotate the latter counterclockwise viewed from the collet end of the chuck. Rotation of the shock sleeve relative to the body is limited by a plug 51 slidable in a groove 25. Wrench holes 56 are provided to facilitate assembly of the chuck. When the sleeve 10 is driven in a counter-clockwise direction the resistance imposed by the work on the rotation of the tool produces clockwise rotation of the body 20 relative to the sleeve 10, thereby driving the member 30 rearwardly relative to the abutment disc and increasing the pressure of the collet on the tool. To release the tool from the collet the shock sleeve 50 is retarded until the plug 51 reaches the end 27 of the groove 25. The sleeve is then released and the spring 60 causes the plug to deliver a hammer blow on the end 26 of the groove driving the body 20 counter-clockwise relatively to the sleeve 10 to loosen the collet. Another tool may be initially gripped in the collet by retarding the shock sleeve, the retardation being insufficient to separate the plug from the end 26 of the groove. In the second embodiment the body is made in two parts 20A and 20B, Fig. 7, with balls 18 carried in a ball race interposed therebetween. The shock sleeve 50A retained on the body by a split ring 57 has a plug 51A extending into a groove 25A in the body part 20B which has splines 38 fitting between splines 71 on the abutment disc 70 in threaded engagement with the body part 20A. When relative rotation occurs between the parts 20A and 20B the abutment disc 70 rotated by the part 20B is displaced longitudinally to effect opening or closing of the collet. The method of operating the release mechanism is the same as that for the first embodiment.