Patent GB-930932-A (GB)
Title: Improvements in or relating to a mechanico-hydraulic drive unit
IPC: G05B19/46
Filed: 1961-04-12
Abstract: 930,932. Machine tool details. EARL A. THOMPSON MANUFACTURING CO. April 12, 1961 [April 18, 1960], No. 13229/61. Class 83 (3). [Also in Groups XXIV, XXVIII and XXIX] A power and control unit for an automatic machine, e.g. a rotary indexing table comprises a base projecting laterally from a centre portion, a transmission mounted above the base, a plurality of rotary cam-actuated pulse transmitting units supported on a member projecting upwardly from the centre portion, a gearbox interconnecting the transmission and the transmitting units, and a prime mover in the base for powering the transmission to drive the transmitting units in unison. The base BA, Figs. 1-3, projects from a centre portion M, and supports a two-speed transmission ST, connected to a pulse transmitting unit HC, and a gear-box GD which supports further transmitting units HC, to drive them synchronously. The transmitter units HC, Figs. 5, 13, each comprise a cam-shaft 10 carrying a number of cams 12, each of which actuate a single acting piston 16 through a follower 18. Each cylinder 14 has a spring-loaded relief valve 22, and a replenishing valve 24 which communicate with a pressurized reservoir 27, and a conduit 26 which supplies oil to a reciprocating or oscillating hydraulic motor for moving the machine parts, several of such motors being shown at 30, 36, 46, 48, 59 in Fig. 13. The motors are so arranged that the total displacements of each motor is less than the displacement of piston 16, to allow oil to be blown over relief valve 22 into reservoir 27 at the end of an advancing stroke, and pistons 16 are retracted by oil under pressure supplied from an accumulator RO through a manifold 60 to the end of each motor. The cam-shaft 10 is driven through two-speed transmission ST, Fig. 13, by an electric motor 132 which drives a shaft 62 by means of a belt 136. Hydraulic clutches 66, 78 are used to select the drive through pinions 64, 68, shaft 70, pinions 72, 74, worm and wheel 82, 88, and shaft 90 or directly through clutch 66 and the worm and wheel, and a hydraulically actuated brake 84 is provided. Two adjustable cams 92 actuate switches to control solenoidactuated hydraulic valves which control the clutches 66, 78. Gear-box GD, Fig. 4, comprises a shaft 104 coupled to shaft 90, at one end, and coupled to the cam-shaft 10 of a unit HC at the other end, and a further two shafts 118, connected to units HC which are driven from shaft 90 through spiral mitre gears 116. Base BA comprises a chamber 130, Figs. 5, 6, containing prime mover 132, a second L-shaped chamber 146 providing an oil reservoir, and a third chamber RO forming a high pressure accumulator to which the return oil manifold 60 is connected. Oil is normally pumped from and then back to reservoir 146 through a passage 152, Figs. 7, 8, in a cover 150, through an opening 154 through which a valve spool 156 extends, and then to a second passage 158 in the cover. However, when accumulator RO requires replenishing as indicated by a sight gauge 172, plunger 162 is depressed to close opening 154 and the oil flows into a pipe 170. A pump AO, Figs. 9-12, provides the flow of oil from reservoir 146 through valve FV, and back to reservoir 146, and also supplies air to the top of the oil in accumulator RO to maintain the oil under pressure. Input shaft 62 of transmission ST, drives a pinion 64, Fig. 13, which as well as driving shaft 70 also drives pump AO through a pinion 182, keyed to a shaft 186, Figs. 9 to 11. An eccentric 192 on shaft 186 reciprocates a spring-urged plunger 194 which actuates valves 200, 202, so that oil is drawn from reservoir 146 through valve 200, and is discharged through valve 202 into passage 152 leading to valve FV, a relief valve 206 being provided to return oil back to reservoir 146 through a conduit 208. Eccentric 192 also imparts harmonic reciprocation to a piston 212 in pump casing 190 having a passage 224, plugged at 226 to allow passage of air in one direction only. Cylinder 218 is similarly plugged at 226, 228, so that as piston 212 is moved downwardly by eccentric 192, air is forced through gasket 232 into a conduit 234 and thence to accumulator RO. Air is also drawn in through connection 230 and when piston 212 moves upwardly the air will be forced through passage 224 into the bottom of cylinder 218 to be compressed therein. The required oil level in the reservoirs of each unit HC is maintained by a valve 252, Fig. 13, in a line 254 connected to accumulator RO, and air is supplied to the top of reservoirs 27 through a conduit 258, having a pressure relief valve 260, pressure regulator 262 and pressure gauges 264, 266 fitted therein.