Patent GB-749374-A (GB)
Title: Improvements in and relating to the adjustment and maintenance of constant peripheral speed of rotary machines such as lathes, winding machines and the like
IPC: B23Q15/10
Filed: 1953-04-29
Abstract: 749,374. Electric control systems. PATENTVERWERTUNG W. REIMERS GES. April 29, 1953 [April 29, 1952; April 17, 1953], No. 11872/53. Class 40(1) In rotating machinery such as lathes and slicing and winding machines in which the working diameter varies, the peripheral speed is maintained constant by a continuously variable gear which, is adjusted according to the difference between a voltage or frequency determined by the peripheral speed required and a voltage or frequency determined by the working diameter and the setting of the variable gear. As shown in Fig. 2, a lathe is driven through a continuously variable gear 15 which is adjusted by a motor 13 and controls the setting of a potentiometer Pn. The potentiometer output constitutes the input of a further potentiometer Pd which has its slider position controlled by the movement of the cross slide 1. The output of the latter potentiometer is applied through the winding of a polarised relay R in opposition to the potential at the slider of a potentiometer Pv which is preset according to the peripheral speed required. When the peripheral speed varies, an out of balance current pulls up the relay and the motor is started by switch 12 in such a direction as to restore balance by adjustment of Pn. In the arrangement, fine adjustment of speed is provided by a potentiometer 9. In a modification, Fig. 3, (not shown), a non-linear adjustable resistor of logarithmic or exponential characteristic may be connected directly between the sliders of Pv and Pn and be adjuster simultaneously with the latter potentiometer so that the sensitiveness of the speed regulation varies with the diameter of the work. A resistance may also be switched in across the tapped portion of Pd so that the peripheral speed varies according to the position of the cross-slide. In a further modification, Fig. 4 (not shown), the potentiometer Pd may have its polarity changed with respect to Pn by means of a changeover switch, for use in machining operations in which the movement of the crossslide is reversed. In an alternative arrangement, Fig. 5, variable transformers Tv, Td, Tn are used instead of D.C. potentiometers, a differential relay R being operated when one or more of the rotors 31, 32, 33 is displaced. Variable condensers may alternatively be used as shown in Figs. 6 and 7. In Fig. 6 a differential relay R is controlled by the push-pull output of valves 36, 37 provided with variable condensers Kd, Kn and Kv in their respective grid circuits. Frequency comparison is used in the embodiment shown in Fig. 7. A frequency which is determined by adjustment of a variable condenser Sv is produced at a valve 38 and is mixed in avalve 39 which oscillates at a frequency determined by variable condenser Sd. The resultant frequency is applied to relay R over oscillatory circuits 40, 41 and an amplifier 42. The two oscillatory circuits are off tuned and their respective resonant frequencies are determined by a variable condenser Sn. Balance is obtained when the resultant frequency falls midway between the resonant frequencies of the two oscillatory circuits. The arrangement may be used with turret lathes, Fig. 8, in which a drum 101 selectively connects different preset potentiometers Pv according to the peripheral speed required for a particular operation. In certain positions of the drum, constant angular speed of the work is obtained by disconnection of Pd at contacts 105. Instead of potentiometer Pn, use may be made of a generator Gn, Fig. 9, which is driven from the output side of the variable gear or from the work spindle and is connected directly across Pd.