Patent GB-677972-A (GB)
Title: Improvements in or relating to a loading device for automatic screw making and similar machines
IPC: B23B13/02
Filed: 1951-02-16
Abstract: 677,972. Automatic lathes. BROWNE & SHARPE MFG., CO. Feb. 16, 1951 [March 15, 1950], No. 3811/51. Class 83 (iii). [Also in Group XXIII] An automatic screw machine comprises a magazine having a number of barrels 44 which receive stock bars and are indexed successively into alignment with the work spindle of the machine, a pusher 90 entering the aligned barrel to feed a bar therefrom into the work spindle, valve - controlled means operated by fluid pressure for indexing the barrels and advancing and retracting the pusher, and means acting automatically when a bar being worked in the machine has been used up to index the magazine and cause the pusher to feed a new bar into the work spindle. The magazine barrels 44, Figs. 1 and 3, may be of circular or U cross-section and extend through a number of spaced discs 42 mounted on a central shaft 40 and rotatably supported on rollers 30 carried by cradles 28 on a table 20. The magazine is indexed to bring each barrel in turn into alignment with the work spindle by a pawl 52 which co-operates with a ratchet-wheel 48 on the shaft 40 and is carried by a slide 54 operable against a spring 68 by a compressed air motor 62, 64. The magazine is held in indexed position by a spring-pressed pawl 70 and is braked by a flexibly-mounted band 78 passing over a drum surface 80 on the magazine. The push-rod 90 is actuated by the piston 98 of a compressed air motor, the cylinder 92 of which is itself slidable on the table 20 by the piston-rod 104 of a second compressed air motor 100 mounted beneath the table 20. Initially, the rod 90 is fed forward with the cylinder 92 by the motor 100, but during the latter part of the movement a clamp 114, operated by a compressed air motor 116, grips the piston-rod 104 and the rod is fed forwardly only by the motor 92. Four solenoid-operated valves 230, 232, 234, 236 control the motors 62, 92, 100, 116 and also three further motors 150, 180, 222 operating the main clutchlever of the machine and the stock stop. The control of the valves also includes (a) a switch 130 operated by a plunger 126 disposed between the magazine and work spindle for engagement with a bar fed from the magazine, and (b) a switch 133 operated by an arm 132 engaging the push-rod 90. In operation, the passage from under the plunger 126 of a bar being worked in the machine actuates the switch 130 so that the motor 62 indexes the magazine. An electric timer 236 is also energized so that, after a predetermined time, the motors 100, 150 are energized to cause respectively, (I) movement of the push-rod 90 into the aligned barrel 44 and (II) movement of a latch 154, Fig. 7, into the path of the cam-controlled feed lever 135 of the machine during its normal feed movement, whereby the lever 160 carrying the latch 154 is rocked so as to move the main clutch lever 146 of the machine to the " stop " position; the machine will then be stopped except for the rotation of the work spindle. When the leading end of the bar in the barrel is about to enter the work spindle, it actuates the switch 130 to energize the motors 116, 92, 222; advance of the push-rod is then continued by the motor 92, and the stock stop is moved by the motor 222 to permit ejection of the waste end of the stock. Actuation of the switch 133 by the arm 132 dropping into a notch 134 in the push-rod then energizes the motors 222, 92, 100, 180 so that the stock stop returns to operative position, the pusher-rod is retracted, and the main clutch lever is moved to " start " position. In the modification shown in Fig. 9, the pusher is a flexible cable 274 which is also used to impart the stepped feed movements to the bar stock against the usual stop. For this purpose, a feed tube 270 forms an integral part of the machine and has slight axial movement against a spring 272. The cable, housed in a tube 274, is operated from the piston 280 of a compressed air motor 278 and its forward end consists of a rotatable cap on a spring- pressed stem. A bar-positioning device between the feed tube 270 and magazine consists of two rollers 308, 314 on blocks which are slidable vertically by compressed air motors 344, 348. When a bar passes between the rollers, the rotation of the roller 314 acts through gearing to drive an endless band 326 passing over pulleys 322, 328. In operation and assuming that a bar has been fed into the machine and completely worked upon therein, the pusher head engages the restricted end 425 feed tube 270 and moves the latter axially to actuate a switch 426, whereupon the motor 278 retracts the pusher. At the end of the rearward movement of the latter, the piston 280 causes a pin 427 to actuate a switch 428 to effect (a) indexing of the magazine, (b) shifting of the stock stop to inoperative position, (c) movement of the main clutch lever to " stop " position, and (d) inward movement of the rollers 308, 314. The indexing action of the pawl 52 also operates a switch 423 to start the feed of the pusher. When the leading end of the bar reaches the rollers, the roller 314 causes the band 326 to move until, with the bar advanced to the desired extent into the machine, a dog 332 on the band actuates a switch 338 to move the main clutch lever of the screw machine to " start position; the rollers are also withdrawn from the bar and the stock stop is moved to operative position. The barrels 44 of the magazine are re-loaded automatically one at a time following the discharge of a bar into the machine by the device shown in Fig. 14. This device comprises two rollers 434 driven by a motor 436 and co-operating with rollers 432 for feeding a bar through a guide tube 430 into the aligned barrel 44; before passing to these rollers the bar is straightened by rollers 440, 442. A continuously-rotating saw 446 for cutting off the bar is disposed adjacent the guide tube 430 on a counter-balanced slide 450 which is movable upwardly and downwardly by a compressed air motor 464. The feed motor 436 is controlled by a switch 476 actuated by the indexing movement of the ratchet-wheel 48 and the movements of the saw by a switch 480 actuated by the leading end of a bar fed through - the barrel. Specification 300,619, [Class 83 (iii)], is referred to.