GB544396A - Improvements in and relating to power transmissions for machine tools - Google Patents

Abstract

544,396. Hydraulic power transmission. VICKERS, Inc., and ESCH, R. E. July 23, 1941, No. 9286. [Class 69 (ii)] A hydraulic power transmission device for operating machine tools such as a milling cutter 10 in which the slide 22 carrying the tool is operated by a motor 26, 27 from a pump 28 is provided with a rotary hydraulic motor 24 for actuating the cutter and the slide 22 is first advanced at a rapid rate to bring the tool up to the work and is then slowed down to feed rate. The arrangement is such that the flow to the motor 24 is blocked during the rapid traverse of the slide. The device comprises a main selfcentring control valve 40 adapted to be operated by electromagnets 92, 94 controlled by relays 96, 98, and when the valve is in the centre position shown the discharge from the pump 28 is byepassed via pipe 42 to the tank 32. On operation of a starting switch 100 the relay 96 energizes magnet 92 and the valve 40 is moved to the right and the liquid flows from pipe 34, valve 40, pipe 44 to a pressure-responsive sequence valve 46, pipe 44 to a cylinder 18 with a piston 20 which operates a work clamp 16 to engage the work 12. Subsequently the pressure builds up in pipe 44 and valve 46 moves to the left to open up a pipe 50 from which the liquid passes through a pressure-responsive valve 52 to the left end of cylinder 26, and the piston 27 moves the slide 22 quickly to the right. The return circuit from the right end of the cylinder 26 includes two parallel pipes 78, 80 passing through a flowresistance valve 82 and a blocking valve 84 respectively. The quick traverse of the slide 22 is checked when an adjustable cam 88 thereon closes the valve 84 and the outlet is restricted causing pressure to build up in pipe 50 and consequent opening of valve 52 and operation of motor 24 which receives its supply of liquid via a flowregulating valve 60 and a reversing valve 58 connected by pipes 66, 68 to the motor and having a pipe 64 which may be connected to exhaust. The motion of the slide 22 is reversed when a cam 110 operates a limit switch 108 for energizing the relay 98 which reverses the valve 40. Pressure is then directed via pipe 70 and valve 72 to the upper end of cylinder 18 to release the clamp 16 and when the piston 20 is fully retracted pressure builds up and opens valve 72 to connect the pressure to the right end of cylinder 26 via pipes 78, 80 and valves 82, 84 which have free passage from right to left. Discharge from cylinder 26 is via pipe 50 and valves 46, 40, and in view of relief of pressure in pipe 50 valve 52 moves to the right and stops operation of motor 24. Finally cam 110 on the slide 22 operates a limit switch 114 to cause de-energization of relay 98 and magnet 94 and the valve 40 returns to its centre position and the pump 28 is byepassed to tank. Drainage conduits 90 are provided for oil which seeps past the various valves 40. The valve 60 may be of the kind described in Specification 399,609.