Patent GB-1284128-A (GB)
Title: A device for controlling speed of rotation of a filament-winding spindle
IPC: D01H1/30
Filed: 1969-08-07
Abstract: 1284128 Spindle motors; building motion KOJIMA DENKI SEISAKUSHOKK and H KANAI 7 Aug 1969 [8 Aug 1968 14 Nov 1968 4 Dec 1968 5 July 1969 (2)] 39598/69 Heading DID [Also in Divisions G3 and H2] The speed of an electric motor driving the filament winding spindle of a ring spinning or twisting machine having a filament guiding ring rail which has reciprocating movement parallel to the axis of the spindle is controlled in response to a first voltage signal which causes the motor to start smoothly from rest and reach an initial working value, a second voltage signal causing the speed to vary according to a predetermined basic programme, a third voltage signal which is a measure of the actual, instantaneous, speed of the spindle, and a fourth voltage signal which rises and falls synchronously with the reciprocating movement of the ring rail. The object is to maintain a substantially constant tension on the filament, particularly at start and finish. The first voltage is produced by a thyrister bridge (Fig. 2, not shown) whose output is controlled by a unijunction transistor in response to a RC circuit 4. Thus a smoothly increasing voltage is produced over a time of about 10 seconds; it is limited by a zener diode. This is applied to a resistor network (Fig. 4, not shown) which includes a servomotor driven potentiometer producing the second signal. The servomotor is energised when a transistor circuit (Fig. 10, not shown) detects that the initial working voltage (the zener voltage) has been reached and its speed is set by a variable transformer. The output voltage of the potentiometer circuit is thus increased up to a maximum and constitutes a reference voltage with which the third signal (from a tachogenerator) is compared. The potentiometer remains at its maximum setting for a predetermined time or number of spindle revolutions, after which its servomotor is operated in the reverse direction to decrease the speed back to its initial working value. During the "steady" period the reference voltage is modulated by the fourth signal. This may be done simply by the periodic switching of a resistor in the reference voltage circuit, but preferably a smoothly varying effect is produced by a ring counter (Fig. 14, not shown) which switches graduated resistors in stages in response to pulses produced by a switch actuated by pins selectively placed on a disc driven by a shaft which also carries a cam for reciprocating the ring rail. (Fig. 15, not shown). As shown in Fig. 1 the resulting speed error signal (produced by comparison of the third signal with the combination of the first, second and fourth signals), derived from the devices 4 .. 9, is applied to a magnetic amplifier 10 connected to a pulse transformer 11 which triggers a thyrister 12 in the armature circuit of a d.c. spindle motor 3. The thyristor rectifies an a.c. supply Eo and its firing angle is varied according to the speed error signal. In an alternative embodiment, Fig. 23, the spindle motor is a three phase induction machine I.M. and its speed is controlled by the circuit shown, in which thyristors SCR1.. SCR3 are triggered in rotation by a ring counter (Fig. 24, not shown) at a frequency determined by the speed error voltage. The arrangement is such that the thyristors effectively interchange the coupling between supply phases UVW and the motor windings at a multiple of the supply frequency, thus varying the speed of the rotating field in the motor. The voltage applied to the motor is also varied by adjustment of the "on" time of each thyristor. The invention may be applied to control the speed of a number of spindle motors, using a common first signal device but respective devices for the other three control signals. However, the potentiometers producing the second signals are adjusted in unison by a common servomotor (Figs. 18-20, not shown).