Patent GB-720329-A (GB)
Title: Improvements in or relating to machine tools and more particularly to automatic toolfeeding apparatus for lathes and other machine tools
Inventor: BUELL TIMOTHY BURR
IPC: B23Q15/00
Filed: 1952-06-10
Abstract: 720,329. Automatic lathes. SUNDSTRAND MACHINE TOOL CO. June 10, 1952, No. 14600/52. Class 83 (3). An automatic lathe, &c., has means for actuating a carriage and a tool-carrying crossslide through a cycle, wherein the tool is moved in one direction with respect to the spindle axis and adjusting means are operable after a machining operation to move the cross-slide relative to the spindle to take a deeper cut during a second cycle of operation, said adjusting means being all mounted on the cross-slide and comprising a member slidable relative to said cross-slide transversely of the spindle axis, a motor connected to said member for moving it relatively to the cross-slide, and a number of control members operable upon relative movement of said member and cross-slide to control actuation of said motor. The lathe bed 20, Figs. 1 and 2, supports a front carriage 23, carrying a cross-slide 24 with longitudinal turning tools 25, and also a rear carriage 26 adjustable along the bed for working in different positions, carrying a rear cross-slide 27 with facing tools 28. The lathe spindle 21, Fig. 3, is driven by a belt 31 from a motor 30 having a conventional brake operated by a solenoid release coil BR2. Pick-off gears 33 are provided in the drive to the spindle. The drives for carriages and cross-slides operate at feed and rapid traverse rates and the feed drive comprises a gear 40 on the spindle, further gear trains 41, 42, pick-off gears 44, gearing 46 and a planetary gear device 47. The latter includes a sun wheel 49 on a shaft 50 which, through further gearing, drives a feed screw 53 engaging a nut 55 for the longitudinal motion of the front carriage. For rapid traverse the left-hand side of the planetary gearing is connected through sun wheel 56 and belt 59 to a reversible rapid-traverse motor 62 fitted with a solenoid brake release BR1. When the motor 62 operates, its drive is superimposed on the shaft 50 to give high-speed forward or reverse motion to the front carriage. The shaft 50 also drives through gearing 69 a shaft 72 carrying a splined worm 74 which meshes with a worm wheel 75 on a shaft which carries a cam drum 77 for operating the rear cross-slide for facing. Depth of cut feeds.-The front cross-slide is formed with a bore 84, Fig. 2, extending transversely and a cylindrical member 85 is slidably mounted in the bore and carries a cam follower roller 86 engaging a cam slot 87 in a cam bar 88. The latter is secured to the lathe bed by a bracket. The cam slot is provided with a portion 87a, Fig. 1, parallel to the lathe spindle axis, a diagonal portion 87b and a further portion 87c parallel to the spindle axis. During the longitudinal motion of the front carriage the cam bar moves the cross-slide and tools from a withdrawn position diagonally towards the cutting-start position and thereafter at the point of further advance during the turning operation. Upon reversal of the carriage, reverse movement of the tools takes place until they are withdrawn clear of the work. The follower 86, Fig. 2, is maintained against the cam slot by a spring 89 and for adjustment of the cut the cylindrical member 85 is adjustable in the bore 84, the former having a central bore 90 and a nut 91 secured therein. A feed screw 92 engages the nut 91 and also carries a worm wheel 93 which meshes with a worm 94 carried on a shaft 95 of a reversible electric motor 96. A bevel gear 97 on shaft 95 meshes with another bevel gear 98 which is squared at its outer end 100 for manual adjustment of the cut. Two or more successive cuts may be made automatically, the adjustments being made by the motor 96 as follows. Limit switches 1LS, 2LS, 3LS, Fig. 1, are arranged on the cross-slide 24 and are actuated by members 105 extending radially from a disc 105a on the upper end of a shaft 106. The latter is rotatably supported in the cross-slide and carries at its lower end a pinion 108 which meshes with rack teeth 109 on the adjacent side of the cylindrical member 85. The rear slide is similarly controlled by limit switches 4LS, 5LS, but is not provided with a cam bar since it is not arranged for automatic longitudinal motion. Electric control. The arrangements shown are for three turning operations and two facing operations and the electrical connections are shown in part in Fig. 4. A three-phase supply is designated at L1, L2, L3, the motor 62 as shown being provided with rapid-approach switch RA and rapid-return switch RR. The motors 96 and 118 for putting on cut are provided with spring-applied brakes and plugging arrangements FSB, RSB respectively, for accurate control. The contacts RA, &c., are electromagnetically operated and associated with relays, the operating coils of which are in the control portion of the circuit. The spindle motor 30 is, preferably, provided with a reduced voltage starting device comprising a transformer T5 connected in parallel with switch contacts MR through contacts MS on the line side and contacts MS1 on the motor side. The spindle motor drives through a magnetic clutch, the operating coil for which, SC, is energized from a rectifier R3 which, in conjunction with a resistor 206, reduces the current through the operating coil when the clutch is first engaged to give a smooth pick-up. In the event of an overload on any one of the motors, one of the thermal overload switches 211, 212 opens and stops the spindle motor. Timing of the switching devices is effected by a control drum 68, Figs. 3 and 6, which is driven from the shaft 50 by worm gearing 65, 66, and which operates a drum switch 330 through the medium of an actuating arm 338. Dogs 334, 335, 336, Fig. 6, are provided on the control disc 68 which may be graduated to facilitate setting, and these act upon a pin 337 projecting from an arm 338 which is fixed to the shaft of the drum switch. Connected between the dog 334 and the dog 335 is an arcuate bar 340 which overlies the pin 337 and prevents rocking of the switch either manually or automatically from feed to rapid-approach position while the front carriage 23 is within the limits of feed movement as defined by the spacing of dogs 334, 335. Specification 490,427 is referred to as having similar control gear.