GB887266A - Improvements in and relating to electrical control means for drafting apparatus - Google Patents

Abstract

887,266. Automatic control systems. INDUSTRIAL NUCLEONICS CORPORATION. Dec. 31, 1957 [Feb. 20, 1957], No. 40489/57. Class 38 (4). [Also in Groups IX and XL (b)] Apparatus for drafting textile fibres comprises automatically controlled means whereby the weight per unit length of the output sliver is maintainedsubstantially constant. As shown, a plurality of raw slivers 10 are fed into a gill box comprising feed rolls 11, 12, a faller section 13, and delivery rolls 14, 15, a number of faller bars 16 being each equipped with protruding pins to process the fibres which form the slivers 10. Rotation of screws 19, 20 carry the fallers engaging the slivers to the right until they reach the output end of the section 13, whereupon they are disengaged and returned to the feed end by means of screws 18, 21. A motor 30 drives the section 13 and rolls 11, 12 at substantially constant speed, whereas the rolls 14, 15, calendar rolls 37, 38, and coiler 40 are driven through transmission 42 so that the speeds of the latter machine elements may be adjusted continuously by control shaft 44. A density-sensing element utilizes a radioactive source 50 and a detector 52 which develops a signal current for indicating the density of the fibres passing between the source and detector. The signal voltage applied to resistor 60 is compared with a fixed voltage from network 68, the output of amplifier 62 being coupled back so as to tend to maintain the amplifier-input at substantially zero potential. An indicator 72, responsive to the output voltage of the amplifier 62, is calibrated by potentiometer 74 so that its zero centre position corresponds to a selected density of fibre. Potentiometer 76 allows adjustment of the span of deviations from the centre-position. A network 84 provides a voltage representing the desired density of the sliver, this voltage being continuously subtracted from the voltage signal indicating the measured density, whereby the error voltage is applied to amplifier 102 which energizes servomotor 104 for driving the control shaft 44 of the transmission 42. The servomotor also drives a tachometer generator 108, and a portion of the tachometer voltage is fed back to the input of the amplifier 102 in opposition to the error signal voltage. Thus, the speed of the servomotor is maintained instantaneously proportional to the magnitude and direction of the error in the measured density of the sliver and, over a given period of time, the total amount of correction applied to the control shaft 44 is proportional to the time integral of the error signal over the same period. Specifications 873,629 and 887,267 are referred to.