Patent GB-874605-A (GB)
Title: An automatically controlled machine tool
IPC: B23Q15/00
Filed: 1959-10-19
Abstract: 874,605. Electric copying-machines. KEARNEY & TRECKER CORPORATION. Oct. 19, 1959 [Nov. 28, 1958], No. 35271/59. Class 38 (6). [Also in Group XXII]  A machine tool comprises power-driven work- and tool-supports 53, 34, means for moving a workpiece to, and removing another from, the work-support, and switch means actuated by the work-moving means for selecting one of a pair of programme control systems. In a drilling or face milling machine, the tool spindle 34 is rotated by a reversible motor 35, Fig. 11, in a head 29 moved by a reversible variable-speed motor 47 on a saddle 26 adjustable vertically by a similar motor 46 on a column 21 which can be traversed by another motor 45 along a bed 18. Tape readers 51, 52 selected by switches 426L, 426U control the positioning and machining movements, one reader 51 controlling the operations on the workpiece on a pallet 54 and the other reader 52 controlling those on a workpiece on a pallet 55. If two machining operations are carried out at one position, a signal confirms the position between the operations. The two pallets 54, 55 are alternately moved from an unloading station to the indexible work-table 53 to which a pallet is clamped. When full clamping pressure is reached, a switch is actuated to energize the required programme reader. The machine may be modified to produce sequentially more than two different workpieces by providing more than two programme readers. To move the pallet 55 to operative position and to remove the pallet 54 from the table, a bar 88 is advanced through rack gearing driven by an hydraulic motor 120. A similar bar 72 and motor 122 return the pallets when an operation has been performed, the bars each having two spring- pressed pushers 96, 97 which are pushed down by fixed lugs when the bars are in withdrawn positions. A pallet engages ribs on a member 66 Fig. 2, at the operative position and is clamped against locating bosses 202, 203 on the table 53 by a rod 214 operated hydraulically within a member 160. The pallet is initially clamped lightly against the bosses 202, 203 to allow for correct alignment. The member 160 forms part of a cylinder which can be raised and lowered to disengage the table 53 from wedge-shaped clutch teeth 156 on the machine bed. When raised, the table can be indexed by a motor 151 driving through gearing 153, 154. Each reader 51, 52 has switch plungers entering holes in a tape. The information is converted and then stored in alternately used registers to control positioning and velocity of the slides. Information is also stored to determine the spindle speed and the position of the table 53. A reading head 287X on the column 21 and a scale 288X on the bed 18 supply positional feedback information to the converter 277. Similarly, a tachometer 290X supplies velocity feedback information. Other reading heads 287Y, 287Z, 287T and tachometers 290Y, 290Z, 290S provide feedback information on the other slides and the spindle. In operation, the machine is set up initially with the pallets both withdrawn. A push-button advances a pallet to the operative station and a further button starts the cycle. Thereafter push-buttons are depressed successively to feed one pallet while removing another and to restart the cycle. Whenever a cycle is complete, a lamp is illuminated to indicate that the pallets may be moved. The electric driving motors may be replaced by valve-controlled hydraulic motors. In a modification, the head 29M, Fig. 12, carries a turret-holder 502 having a series of pivoted holders 503 carrying tools T54, T55 for machining workpieces carried by the pallets 54 and 55 respectively. The tapes then contain additional information and the turret carries a reading head to provide feedback. To change a tool, an arm 504 and a tool T54A are first swung to the positions shown. The arm 504 is then moved to pick up, by means of spring-pressed detents in recesses 506, 507 the tool T54A and the tool T54B previously in use and to interchange them. Referring to Fig. 13, the turret 502 is indexed by a reversible motor 513 driving through gearing 509, 510 and a tapered locking plunger 515. A tool holder 503 is pivoted outwardly by a piston 547 acting through rack gearing 550 which also acts through a shaft 552, gearing 553, 554 and an arm 556 to swing a tool-change mechanism support 560 to operative position. A piston 589 is then operated to move a rack 596 and swing the arm 504 to engage the tools. A sequence control cam 599 is also rotated to unclamp the tool T54B by means of an hydraulically operated draw-bar 622 and to move the arm 504 by a piston 645 to withdraw both tools. The arm is then rotated by a further 180 degrees by actuation of a secondary piston 577 to interchange the tools. The arm is next moved by the piston 645 to position the tools in the sockets, that in the socket 503 being retained by a spring-pressed detent and that in the spindle by actuation of the draw-bar 622. The arm is finally rotated 270 degrees in the reverse direction, while being moved outwardly by the piston 645 to clear the tools, and the arm and socket 503 are returned to their initial positions. Specification 871,095 is referred to.