Patent GB-622209-A (GB)
Title: Improvements in and relating to lathes and other machine tools
IPC: B23B19/02
Filed: 1946-01-15
Abstract: 622,209. Lathes. WARNER & SWASEY CO. Jan. 15, 1946, No. 1396. Convention date, April 11, 1945. [Class 83 (iii)] [Also in Group XXXVII] A lathe or other machine tool having control means for stopping the spindle in a predetermined position, the control means being adapted to change the spindle speed from normal working speed to a pre-stopping speed prior to being stopped is characterised in that the spindle is driven by an electric motor and the control means includes a circuit having switches adapted to be actuated to change the spindle speed and includes co-operating means whereby the motor is rendered inoperative and braking means is applied to the spindle to effect stopping at a predetermined position. The main spindle 12, Figs. 2 and 4, of the lathe, driven from a self-contained electric motor in the base of the machine, is provided with an adjustable ring 19 which may be secured by a set-screw 20 in a predetermined position for stopping the spindles. The ring has a raised portion 21 on its periphery adapted to engage a roller 29 on a vertical stud 26 slidable in a bracket 24 within the machine headstock. A collar 30 is pinned to the lower end of the stud and a compression spring 31 tends to withdraw the stud and roller away from the cam ring 19. A stronger compression spring on the other side of the collar bears through a further sliding collar on to the short end of a cranked lever 36. The other end of this lever carries the armature portion of a solenoid PS. The lower end of the stud 26 carries a laterally extending arm 34 which operates a microswitch LS1. This arm and the roller 29 are out of contact with the switch and cam ring respectively when the solenoid is not energized. When, however, energization of the solenoid takes place, the roller is raised into a position where it may be operated by the cam portion 21 to depress the stud 26 and open switch LS1. The brake shoes 39, 40, Fig. 6, are normally maintained in the open position by a lever 49 operated by the energization of a solenoid B, when, however, the latter is de-energized the brake is applied through the spring 44. Control circuit. The control switches are mounted in a panel on the lathe headstock (not shown) and comprise start and stop buttons 51, 52, Fig. 7; a control 54 for "high" or " low " spindle speeds with an intermediate "off" position, a control 56 for " forward " or " reverse " spindle drive also with an intermediate " off " position and control 58 for switching in the automatic spindle stopping means. The wires 59, 60, 61 form part of a multi-phase circuit with a main switch 62 leading to " forward " and " reverse " contactors 55, 57, respectively controlled by the member 56. The wires are then led to " low " and " high " speed contactors 63, 64 respectively to the motor 17. These contactors are interlocked so that only one switch of each pair can be closed at a time. An auto-transformer AT is energized through wires 67, 68, 69 and wires 70, 71, 72 lead from this transformer to three contacts on one side of the normally open contactor CR1 which effects'the slow constant non-working speed of the motor 17 preparatory to terminating this motion and applying the brake to stop the spindle in the predetermined position. The wires 59 and 61 are connected to the primary coil of a transformer T by wires 73, 74 and brake solenoid B is connected across these wires by the connections 75, 76. The control circuits for the contactors above are operated at a reduced voltage from the secondary of the transformer T. A plugging switch 89 is employed for the motor which automatically reverses the current thereto to obtain a rapid slow down when changing from " high " to " low " speed running.