GB976690A - Hydraulic motion control system, particularly for a machine tool - Google Patents

Abstract

976,690. Grinding. CINCINNATI MILLING MACHINE CO. May 29, 1963 [July 10, 1962], No. 21456/63. Heading B3D. [Also in Division G3] The wheel-head 11 of a grinding machine, adjustable on a screwed piston-rod 16 by a hand wheel 20, is advanced towards the workpiece 15, in response to movement of a hand lever 62 to a position determined by a ball detent 60a, until an abutment 16a on the pistonrod engages an adjustable abutment 47 whereafter the wheel head is caused to advance in correspondence with further movement of the hand lever. The piston-rod 16 carries a doubleacting piston 18, chambers 38, 40 on either side of which are always connected by conduits 37, 39 to annular grooves 35, 36 on a slidable sleeve 26 which is movable by pressure changes in a chamber 54 connected to a source of pressure 28 through an elongated port 56 and to sump through an elongated port 64 controlled by a pilot valve member 67. The chamber 54 is therefore maintained at an intermediate pressure which is opposed to the source pressure acting on a smaller area of the sleeve 26 in a chamber 53, and any reduction of area of the port 64 due to leftward movement of the pilot valve member raises the pressure in the chamber 54 causing leftward movement of the sleeve 26 until balance is restored by throttling of the port 56. With the parts in the positions shown, pressure from the source 28 entering an annular groove 31 on the sleeve 26 can pass to the groove 36 and chamber 40 to hold the wheel head retracted, but on leftward movement of the sleeve 26 the pressure and exhaust connections to the piston 18 are reversed, a valve member 27 remaining stationary, causing the wheel head to advance until the valve member 27 is brought to the lapped position by the abutments 16a, 47, whereafter the wheel head can only move in correspondence with the lever 62. In a modification, separate advancing and retracting pistons for the wheel head are provided and the hand lever, which operates the pilot valve through a cam, is movable about a second axis to operate a throttle valve in the conduit leading to the wheel head advancing piston.