Patent GB-920745-A (GB)
Title: Automatic cycle control mechanism for a machine tool
IPC: G05B19/04
Filed: 1959-11-27
Abstract: 920,745. Copy-milling. CINCINNATI MILLING MACHINE CO. Nov. 27, 1959 [Dec. 19, 1958], Mo. 40365/59. Class 83(3). [Also in Group XXIV] A machine tool with an automatic cycle control mechanism comprises a support for one or more driven elements, a source of potential selectively connected by a stepping switch and a plurality of selector switches to circuits for controlling the elements, and a trip dog on one element operating a switch to disconnect one of said circuits and to energize the stepping switch in preparation for the selection of the next event in the cycle. In a spiral milling-machine, a table 102 is traversed by a motor 103 rotating a screw 104 on a saddle 100 which is angularly adjustable on the machine bed 101. A head 105, carrying a spindle 108 driven by a motor 109, is adjustable vertically by an hydraulic piston 107. Cutters 111 and a flywheel 115 are mounted on an arbor held by supports 113 and attached to the spindle 108 by a draw-spindle 112. Three workpieces are carried on the table 102 between tailstocks and a headstock 121 having three spindles in longitudinally adjustable quills which permit the workpieces to be staggered when the saddle is set at an angle. The work-spindles are rotated by an hydraulic motor 124 driving through worm gearing 125. To determine the lead angle of the work, an angularly adjustable bar 132 on the table 102 co-operates with a follower 131, moved upwardly by a weight 331, in a slide 127 supported by the saddle. A similar bar 138 and follower 137 determine the feed depth when the work is tapered. The two followers control the motor 124 and the piston 107 through servo-mechanisms. The work is indexed through a disc 183, Fig. 7, having 24 notches 179, each indexing step consisting of any factor of 24 according to the setting of a pin 185 in a stop-plate 187. The stop-plate is urged clockwise against a pin 213 by a spring 209. A disc 191 carrying a block 204 and a masking plate can be moved counter-clockwise by an hydraulically operated rack 182 engaging a pinion 194 on a shaft 196 carrying the disc. When the disc is moved clockwise, a pawl 205 thereon urges the indexing disc 183 clockwise so that it is precisely positioned by a pawl 215 pivoted on the pin 213 and engaging a machined face of a notch 179. A second pawl 214 on the pin 213 prevents counter-clockwise movement of the disc 183. To set the initial angular position of the headstock spindles, a clutch knob 229 is rotated relatively to the disc 183. In operation, the piston 182 moves the disc 191 counterclockwise : when the block 204 engages the stop 185, the stop plate 187 is carried round until a shoulder thereon engages a pin 210. A notch in the plate 187 then actuates a switch 6LS to return the plunger, the disc 183 being carried round by an amount determined by the previous setting of the stop 185. The indexing mechanism is mounted on a column 241 and is accessible by a door 242. Fluid for the motor 103 is supplied by a pump 250 and that for the piston 107, the motor 124 and a depth tracer motor 257 by a pump 251. The motor 103 is controlled by a reversing valve 290, a valve 280 directing the fluid to low- or high-speed lines, a valve 277 controlling the rate of flow, and a valve 293 for by-passing the valve 277 for rapid traverse. The piston 107 is controlled by a valve 300 which is regulated by the current in a coil 303 surrounded by a magnet 304, and by a feedrate valve 313 which is brought into circuit by a valve 307 operated by a dog 310 on the head 105 as it approached the work. The valve 313 is by-passed during upward movement of the head 105. A second coil 342 controls a valve 340 to control the motor 124. The current in the coils 303, 342 is determined by the positions of the followers 137, 131 which through ball-nuts and screws 368, 375 position coarse and fine synchros CX-1 to CX-4. The initial position of the spindle head is controlled by a hand wheel 370 for adjusting the synchro mechanism. In a cycle of operation, the table 102 is moved rapidly to the left until a dog 389 operates a switch 2LS to initiate feed-speed. When a dog 391 operates a switch 4LS, the table is stopped and the head is moved rapidly down until the dog 310 operates the feed valve 307. A dog 393 then operates a switch 1LS and the head stops when the follower 137 contacts the cam 138. The table moves to the right at feed-speed until a dog 387 operates the switch 2LS. The table stops and the head is raised at rapid speed. A dog 386 operates a switch 3LS and the work is indexed. To set up a cycle, switch arms 81-87, Fig. 13A, are set to select any one of seven contacts set in seven banks. The switch arms are connected to contact 78 which are selected in turn by one arm 76 of a double rotary stepping switch. When the stepping switch selects an index position, it is automatically returned to its " home " position. The second arm of the selector switch causes lamps to be illuminated to denote which contact bank is operative. A manual switch enables the circuit to be set for push-button control. Reference has been directed by the Comptroller to Specificatjon 889,148.