GB1064760A - Improvements relating to steady rests for rotating workpieces - Google Patents

Abstract

1,064,760. Grinding. G. H. PORATH. Dec. 11, 1963 [Dec. 13, 1962], No. 48846/63. Heading B3D. A steady rest for a rotating workpiece, such as an engine cam-shaft which is to be ground, comprises circumferentially spaced orifices in its bearing surface for the supply of bearing fluid. A plurality of rests (11, Fig. 1) may be used to steady the cam-shaft (C) which is supported on centres (10a, 10b) during grinding of cam surfaces (S). Each steady rest has a base 13, for mounting on the bed of the grinding machine and a primary slide 22 is adjustable on the base by movement of triangular blocks 23 engaging opposite sides of an inclined wall 25 depending from the slide. The upper surface of the primary slide is inclined and supports a secondary slide 30 which is similarly adjustable on the primary slide by triangular blocks 33 co-operating with an inclined wall 34, the movements of the two slides horizontally and vertically adjusting the position of the bearing surfaces of the steady rest. The secondary slide 30 is formed with a lower part 40 having a lower bearing surface 49 which co-operates with an upper bearing surface 48 on an upper part 41 mounted on a pivot 42 on the lower part; the parts are also formed with mating surfaces 44, 45 and interengaging grooves 47 and teeth 46 for ensuring accurate alignment of the bearing surfaces 48, 49. The surfaces 48, 49 are arranged to have a small clearance, e.g. between 0À0001 inch and 0À002 inch, with the surface of the cam-shaft, and are formed with spaced pockets 51 connected by adjustable orifices, in the form of capillary tubes (53, Fig. 8A) and passages to conduits 59, 64 leading from an hydraulic source of predetermined pressure. The pressure at the pockets is sufficient to support the cam-shaft without mechanical contact with the steady rest. The passages in the parts are also connected to the groove 47 and surface 45 and shortly before the upper part 41 of the rest reaches its fully closed position during loading of the cam-shaft in the grinding machine, a cam (75, Fig. 1) operates a switch (74) to connect the fluid supply to the passages and wash dirt and the like from the groove and surface to ensure accurate closing of the rests, clamps 76 being provided to retain the rests in their closed position. When the pressure at the pockets 51 is sufficient to support the camshaft without mechanical contact with the rests, a pressure switch is operated to start the motor of the grinding machine. The fluid may be machine oil or the coolant used in the machine, such as water soluble oil or waxed based fluid in water. The hydraulic circuit includes a filter which may be of the endless fabric type and a micronic filter. In another embodiment, each steady rest comprises an upper part 101, Fig. 9, pivoted to a lower part 102, the parts carrying members 106 which are radially adjustable by bolts 108. Each member has a pressure pocket (112, Fig. 10) connected by an adjustable orifice (110) and a passage (109) to a conduit (113) leading from the pressure source. Each pocket (112) is also connected by a passage (114) to a pressure gauge (115) whereby the pressure at the pockets can be determined upon adjustment of the members (106) by the screws 108. In another arrangement, the camshaft is supported entirely by the steady rests, the centres 10a, 10b being replaced by stops which limit axial movement of the cam-shaft.