GB1171571A - Machine Tools - Google Patents

Abstract

1,171,571. Machine tool details; hollow spindle lathe. S-P. MFG. CORP. 6 Feb., 1968, No. 5829/68. Headings B3B and B3T. [Also in Division F2] Apparatus for actuating the draw-bar of a lathe chuck comprises a piston 16 which is connected to the rotatable draw-bar and which is movable in a rotating cylinder 18 which has an extension 18a of relatively smaller diameter around which is placed a stationary distributer 12 through which hydraulic pressure fluid is supplied via passageways 25 and 28 to cylinder chamber 19. The piston 16 and cylinder 18 are held against relative rotation by pins 78. The distributer 12 has ports 48, 49 leading into grooves 45, 46 that are aligned with openings into the passageways 25, 28 to supply and exhaust the chamber 19. The distributer is separated from the surface of the extension 18a of the cylinder by a fluid bearing in which pressure fluid is supplied, via conduits in the distributer body, to circumferentially spaced cavities arranged in two groups 34a-34d and 35a-35d, the pressure fluid flowing axially from the cavities to collector grooves 52, 54, 60 and 61 which drain into a drain conduit 56. Any fluid passing axially past the grooves 60 or 61 is picked up by grooves 66 or 67 and flung centrifugally into further collector grooves 64, 65. Restrictive portions 39a-39d and 43a- 43d in the supply conduits control the pressure and flow to the bearing surfaces. Separate pressure fluid supplies are used for operating the piston 16 and supplying the fluid bearing. In an alternative embodiment (Figs. 4-6, not shown) a single pressure fluid supply is used for operating both the piston and the fluid bearing, some of the cavities of the fluid bearing being connected with the fluid supply passageway serving one end of the cylinder chamber and the rest of the cavities being connected with the passageways serving the other end of the cylinder chamber.