GB725439A - Improvements in or relating to lathe centres - Google Patents

Abstract

725,439. Lathe drivers and centres; chucks. GAUCH, E. Feb. 18, 1953, No. 4688/53. Class 83 (3). Lathe drivers and centres.-The pressure of the work on a centre 4 forces the driver 19 or drivers 5 into engagement with the end face of the work through a common pressure-equalizing medium 11, such as rubber, a synthetic plastic, a liquid such as oil or, as shown, a number of small hardened steel balls. A cylindrical member 3, Fig. 10, carrying the centre 4 is slidable, against return springs 12 and within the limits imposed by a pin 13 and slot 14, within a sleeve 1 having either a taper shank 2 or forming part of the lathe spindle, and three drivers 5 having roughened work-engaging faces 6 are slidable in slots in the member 3. At their rear ends, the drivers are widened to provide part-annular feet 9 which almost abut each other and encircle a reduced extension 10 of the centre member 3. Since the surface area of the feet 9 is greater than the area of the end face of the extension 10, an increased force is transmitted through the balls from the centre to the drivers. The sleeve may drive the drivers through ribs on the drivers engaging slots on the sleeves or a transverse rib 15 may prevent rotation of the balls so that all the parts are locked together. A single driver 19, Fig. 13, having teeth 6 acts upon pressure pins 17 passing through the centre member 3 to bear on annular disc 28 behind which are the balls 11. A pressure face 34 is provided in an extension 31 of the centre member 3 by one or more grooves 35 and the balls wedge in those grooves to prevent the extension 31 from sliding completely into a bore 33 in which is a return spring 32. The driver 19 and disc 28 are formed so that they may tilt to allow the driver to accommodate itself to the face of the work, the driver being secured against rubber or other springing means 25 on the sleeve by a pair of bayonet-type fastenings 22, 23 and a slight amount of lost motion being allowed between the pins 17 and the driver. Chucks.-The drivers may be in the form of clamping jaws moved radially to clamp, for example, hollow work.