| 摘要 |
906,963. Drilling and boring-machines; punching. DE VLIEG MACHINE CO. April 22, 1960 [April 24, 1959], No. 14175/60. Classes 83 (3) and 83 (4). [Also in Groups XXXVII and XXXVIII] A machine tool, e.g. a boring-mill, drill-press or punch-press, comprises a base 11, Fig. 2, a work-or tool-table 13 movable in opposite directions on the base by a motor to position the table in accordance with dimensions, from a datum, fed into a device 15 controlling energization of the motor. The device is mounted either on the table or the base and includes a sensing head 23 co-operating with magnetized pins 21 spaced, e.g. 1 inch apart, on a bar 19 mounted either on the base or the table, respectively. The machine is set up, when a workpiece is clamped on the table, to a datum, which may be a line on the drawing from which the dimensions are given, and counters 167, 169, 83, 85, 99 are set to zero by rotating knob 66 for counters 83, 85, 99, and knob 105 for counters 167, 169. Then block 57 is adjusted by screw 193 to centre head 23 on the nearest pin 21. Dimensions to the right of the datum are fed to counters 167, 83, 99. and to the left of the datum to counters 169, 85, 99, and set the position of a cam 139 controlling switches LS1, LS2. The cam is driven from a rack 137 on the table to be restored to a central position, when the table approaches the desired position, where it actuates a selected one of the switches. A lever 95 is moved to position a shutter over that one of the counters 83, 85 not used and simultaneously actuates a switch SW1, Fig. 5, to place either LS1 or LS2 in circuit. The sensing head 23, Fig. 4, is supplied with alternating current from a source 37 and until centred relatively to the appropriate pin 21 supplies a signal to an amplifier 43 which, via transformer 46, feeds a circuit including a relay AR with contacts ARa in a circuit including relays TS, TF controlling the motor speed via different windings, a solenoid 22 controlling a change-speed gear, and relays TR, TL controlling the direction of rotation of the motor. A positioning movement is then started by momentarily closing switch SW2 and can be stopped at any time by opening a switch SW4. Closing switch SW2 energizes relay CR1 and the table moves at a slow speed and after a delay the speed is increased until cam 139 actuates selected switch LS1 and LS2, and de-energizes relay CR1 and energizes further relays causing reversal of the motor and a reduction in speed due to overrun. When the sensing element overruns the selected pin on the reverse direction and to a less extent, contacts ARa close to energize relay CR100 to reverse rotation and reduce speed and this is repeated until the table approaches the position at its slowest speed.
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