Patent GB-490427-A (GB)
Title: Improvements in or relating to machine tools, particularly lathes or the like
IPC: B23Q5/14
Filed: 1937-02-12
Abstract: 490,427. Control of motors. SUNDSTRAND MACHINE TOOL CO. Feb. 12, 1937, No. 4264. Convention date, Feb. 29, 1936. [Class 38 (iii)] [Also in Groups XXII and XXIV] A machine tool has a carriage reciprocable at feed and traverse rates connected through gearing to two electric motors, the second of which is reversible, and so arranged that with the first motor energized the carriage is driven at a feed speed and when both motors are energized, the carriage is driven at a traverse speed for a rapid approach movement, and when the reversible motor only is energized for reverse running the carriage is given a rapid return movement, switch means being provided to obtain a cycle of movement including rapid approach, feed, and rapid return movements. The machine spindle 31 is driven from an electric motor 32, Fig. 4, through belts and gearing. A spindle brake 66 is provided which is controlled electrically through a solenoid and stops the spindle during the rapid return movement of the carriage 39. A further gear and belt drive drives a toothed wheel 96 carrying planetary pinions side which engage sun-wheels on separate shafts 130, 191. The shaft 130 is driven through belts 137 from the reversible electric motor 43, an automatically operated brake and governor-controlled pawl-and-ratchet device being provided on the shaft for stopping it and holding it positively against further turning until released. When shaft 130 is held stationary, the small difference in the number of teeth of the two sun-wheels produces slow rotation of the shaft 191 for a feed movement of the carriage, but rotation of the shaft 130 upon energization of the motor 43 gives a high speed traverse movement to the carriage, again stoppage of the wheel 96 and reverse rotation of the motor 43 gives a high speed return movement to the carriage. The switch means for controlling the machine comprises a three-position drum switch 290, Fig. 13, with contact shoes 292-294, which may be rocked by a hand lever or automatically by adjustable dogs on a disc 330 rotated from the carriage feed gearing of the machine. Starting and stopping of the machine is effected from a push-button station 48, Fig. 1, mounted on the machine headstock and electrical connections, Fig. 20, including line wires L<1>, L<2>, L3 connected to the terminals of a solenoidoperated switch So and also to a manuallyoperated switch M. Switch 377 for the coolant motor 286 is first closed and switch 371, controlled by a knob on the push-button control station of the machine, moved into its closed or " run position. The operator then closes the manual switch M, Fig. 20, and rocks the drum switch 290 (shown developed) to its rapid approach position. This completes the circuit through contacts Dl, D3 and D2, D<4> to the rapid traverse motor 43 and to the brake solenoid 143 to release the brake on the sun-wheel shaft 130, Fig. 4. Simultaneously, the spindle motor 32 is set rotating by solenoid 358 being energized through the drum switch connections and the switch So being thereby closed to complete the circuit to the spindle motor and spindle brake solenoid 69 to release the spindle brake. The rapid traverse of the carriage continues until a dog on the control disc 330 rocks the drum switch to its intermediate feed position. The current to the motor 43 and solenoid 143 is cut off and this motor is thereby brought to rest and held against rotation. The switch So remains closed and the spindle continues to rotate as the carriage is driven at a feed rate. After the carriage has completed the forward movement required, a third dog on the control disc rocks the switch to its rapid return position, breaking the holding circuit to the solenoid 358, stopping the spindle motor 32 and the coolant motor 286. At the same time contacts D3 and D4 are connected, thus connecting terminal T<1> to the line L<2> and causing the motor 43 to rotate in reverse direction ; the control disc is now also rotated in reverse direction and the intermediate dog ultimately rocks the drum switch to neutral position to stop the machine or by using a differently shaped dog the switch may again be moved to rapid approach position and a fresh cycle started, the operation continuing until a stop button is depressed. The spindle motor may be driven independently of the rapid traverse motor by depressing button 363 which completes a circuit from L<2> through manual switch M to line wire L<3>. Now if switch 372 is moved to its " jog position, the spindle will only rotate while button 363 is depressed. Specifications 490,434 and 492,153 are referred to.