GB612855A - Improvements in or relating to chucks - Google Patents

Abstract

612,855. Chucks. ULVSUNDA VERKSTADER AKTIEBOLAG. May 31, 1946, No. 16588. Convention date, June 8, 1945. [Class 83 (iii)] A chuck is provided with an external holding sleeve which is axially displaced to subject a series of balls to radial pressure so that they engage a rotatable and axially movable member to effect opening of the jaws. Secured in the body 2 is a sleeve 8 provided at its upper end with two diametrically opposed radial recesses which accommodate the ends of the rectangular head of a screw 5 having a helix angle sufficiently steep, for instance nine degrees, to prevent it from being self-arresting. The screw engages a member 3 slidably housing the jaws 13 which are provided with grooves 19 (Fig. 4) to engage balls 18 mounted in lugs on an annular jaw holder 15. A thrust bearing 25 is interposed between the latter and the sleeve 8. The jaw holder has two conical surfaces 23, 24 providing a race for a series of balls 21 arranged in bores 22 in the body. Under the action of centrifugal force the balls enter a space 29 in the holding sleeve 26 which is displaceable on the body and provided with an oblique rolling race 30. To open the jaws the holding sleeve is raised, causing the race 30 to bear on the balls 21 and place them in engagement with the jaw holder which is thus rotated together with the member 3 at a speed higher than that of the body and the screw so that the member 3 is downwardly displaced to open the jaws. A slow opening movement is obtained due to the fact that the contact points of the balls on the jaw holder are radially nearer to the centre of the balls than the contact points on the race 30. The jaws are closed by retarding the member 3. Since the jaws and the screw do not move axially, a constant depth of insertion is provided for the tool.