GB946240A - Improvements in speed frames and like textile machines - Google Patents

Abstract

946,240. Automatic tension control. T.M.M. (RESEARCH) Ltd. May 26, 1961 [June 1, 1960], No. 19467/60. Heading G3R. [Also in Division D1] A roving is delivered by drafting rollers to a flyer for winding the roving on to a bobbin, the roving passing a photo-electric cell detector consisting of two triangular plates, the light directed on to the plates being partly cut off by the roving which passes between the plates and a light source. With the roving at the required degree of sag an equal amount of light falls on each plate, the plates being connected in a bridge circuit which is unbalanced to produce an output signal indicating the change in the sag from the required amount. Three such photo-electric cell detectors with associated bridge circuits are provided on a speed frame, the output signals from the circuits being fed to a mixer amplifier producing an output representing the average signal. This signal is transmitted to a power amplifier providing a push-pull output to a magnetic clutch 23 comprising a driving component 27 coupled to constant-speed motor 32, and a braking component 35. The motor 32 drives a roller drafting system 37, flyer spindles 38 and tachometer generator 25, and is coupled to differential gear 39, the other input of which is driven from the output shaft of the clutch 23. The output of the differential is applied to drive the bobbins 40. The output of the clutch is coupled to drive a lifter rail mechanism 41 as well as a tachometer generator 24. A stabilizing feed-back loop between the output of the clutch 23 and the mixer amplifier comprises the generator 24 which produces a signal proportional to the rate of change of speed through a differentiating circuit and is connected to oppose rapid speed changes. The effect of the tachometer generator 24 is opposed to that of the tachometer generator 25, which is also in the feed-back circuit, during stopping and starting operations of the speed frame, but, when the roller drafting system and flyer spindles attain normal running speed, the generator 25 becomes ineffective and generator 24 functions to prevent hunting.