GB300061A - Improvements in centreless grinding machines - Google Patents

Abstract

300,061. Hughes, V. A. B., (Cincinnati Grinders, Inc.). Feb. 24, 1928. Centreless grinding; guides and rests. - A centreless grinding machine is adapted for producing accurately concentric but differentlyshaped surfaces on work-pieces, such as the cylindrical body and tapered shank of a twist drill. The fluted body N, Fig. 3, of a twist drill is produced in a centreless grinding machine in the usual manner and is then gripped in a split collet 13 clamped by a hand-wheel 15 within a work-holder 10 having a cylindrical portion 11 concentric with the collet. The holder is rotatably mounted on the usual work-support M, Fig. 2, by means of a half-bearing 17 and a blade 18 having an upper inclined surface engaging the portion 11, a roller 22 being pivotally mounted on the support, and urged by a spring so as to force the portion 11 against the regulating wheel D. In operation, several work-holders are used in turn, and with a work-piece mounted therein being placed on the support M while the latter is raised by means of a hand operated pinion I engaging a rack on a controlling plunger G to which the support is secured, the roller 22 being moved to one side by a hand lever 28 to allow admission of the holder. On lowering the support the holder is rotated by contact with the regulating wheel D and a grinding wheel E, Fig. 3, which is staggered with regard to the wheel D, is fed in by its slide to cut the correct taper. The wheel E may be dressed to the required taper or alternatively its slide may be inclined. When a work-piece has been completed the holder is removed from the machine and replaced by another holder with a work-piece to be operated upon whilst the previous holder is having its work-piece renewed.