| 摘要 |
908,174. Automatic speed control systems. BUDNICK, G. A. A. Feb. 19, 1959 [Feb. 24, 1958], No. 5757/59. Drawings to Specification. Class 38 (4). In a machine tool, the shaft driving a cutter and the shaft driving a workpiece are each provided with graduated discs associated with photo-electric or other scanning devices delivering trains of pulses through two separate channels. The pulses in one channel are passed through a frequency divider, the other pulses being passed through a multiplier, so as to afford an order of relationship between the pulse trains suitable for comparison. The modified pulses are applied to a frequencycomparator which provides an error voltage for controlling the speed of one of the shafts. In a hobbing machine, compensation for speed deviations between the shafts is effected by an electric motor which is supplied with the error voltage and which is coupled through differential gearing to a variable gear transmission for the hobbing shaft. The electric motor may be replaced by electro-mechanical or hydraulic drives. In another arrangement, the correction is effected by the use of a dynamo-electric machine whose rotor is positioned in accordance with the error voltage. Alternatively, the machine may have two concentric tables coupled across an annular gap by rods of magnetostrictive or piezo-electric material, each rod being surrounded by a coil energized by a control voltage. Variations in the lengths of the rods cause the relative positions of the tables to be adjusted, Fig. 3 (not shown). Instead of adjusting the table, a cutter may be shifted in an axial direction by means of a magnetostrictive or piezo-electric element. A number of pulses may be added to or subtracted from the train of pulses associated with the cutter shaft, these further pulses being derived from a frequency divider which is adjusted in accordance with the angle of slope and the cutter feed. Rotational adjustment may be effected alternatively by shifting the scanning point of the disc on the cutter shaft, Fig. 4 (not shown). In an arrangement for measuring toothed wheels, a gauge wheel is engaged with a wheel to be tested, the gauge wheel being driven and the other wheel being braked to simulate known operating conditions. Graduated discs and scanning devices are associated with each wheel, and frequency dividers for the two pulse trains are adjusted in accordance with the number of teeth of the appropriate wheel. A comparator provides an error voltage which indicates the hobbing deviation, Fig. 5 (not shown). A frequency multiplier which is set to the number of teeth of the gauge wheel, and a frequency divider which is adjusted to the number of teeth of the wheel under test may be connected in one of the pulse channels, Fig. 6 (not shown). |
