GB1084530A - Grinding machine - Google Patents

Abstract

1,084,530. Grinding. HEALD MACHINE CO. Dec. 31, 1964 [Jan. 17, 1964], No. 52999/64. Heading B3D. A grinding machine for finishing a surface of revolution of an annular workpiece 49, Fig. 3, comprises an abrasive wheel 53, a cup 55 adapted to extend around an external surface of revolution 51 of the workpiece with a very small clearance, a non-rotating backing plate 58 adapted to engage a radial surface of the workpiece, means for supplying a viscous fluid to the clearance between the cup and workpiece, and means for rotating the cup. The cup 55 forms part of a work-supporting means 13 and is mounted on the end of a hollow shaft 64 which is connected by splines 66, 67 to a pulley 46 driven by belts 45 from an electric motor. The shaft is formed with a flange 68 which serves as a piston slidable in a cylindrical portion 69 of the bore for the shaft, the opposite ends of the portion being connected by passages 76, 77 to a valve 75 whereby the shaft, while rotating, can be axially moved from the operative position shown, in which the cup encompasses the workpiece, which may be the outer race of a ball-bearing, to a retracted position wherein the mouth of the cup is adjacent a lip on the backing plate 58 to effect ejection of the workpiece from the cup. The plate 58 is carried by a stationary shaft 62 which is disposed within the shaft 64 and is formed with a passage 79 at one end connected by a conduit 78 to a source of viscous oil under pressure, and at the other end connected by passages 81 ... 87 to orifices opening to the inner surface of the cup. The clearance between the cup and workpiece is between 0À001 inch to 0À003 inch and the arrangement is such that as the cup rotates, the oil supplied to the clearance acts as a hydrostatic and hydrodynamic bearing for the workpiece which lags behind the rotational speed of the cup by 20 to 40 r.p.m. The shaft 64 is supported in the housing 11 by a bearing 71 at one end and the bore 65 for receiving the shaft in the housing is formed with a plurality of pockets 72 supplied with oil through passages 73, 74 to form a hydrostatic bearing for the shaft. An unloading and loading apparatus 14, Fig. 1, is associated with the work-supportnig means 13 and consists of a disc 17 which, is mounted on a hollow shaft 18 in the housing 11 and is formed with three work-holding stations 19, 21 and 22. Each station comprises a partcircular cut-out having an annular plate 23 around its edge and has a pair of resilient fingers 24, 25 extending towards the surface of the housing. An inlet shoot 15 is associated with the station 19 and a pod 28 carried by an arm 27 on a shaft 26 is provided for moving a workpiece into the station. A similar pad 37 on an arm 36 carried by a shaft 35 disposed within shaft 18 is provided for ejecting a workpiece into an outlet shoot 16. At the working station 21, a pressure device 32 having fingers 33, 34 is mounted on a shaft 31 rotatable in a bearing 29 to press a workpiece at that station against the backing plate 58. The disc 17 is indexed from station to station by a piston- and-cylinder device 123, the rod of which has a pawl co-acting with a ratchet-wheel having three notches to move the disc in 120-degree steps.