GB782015A - Improvements in or relating to tension control - Google Patents

Abstract

782,015. Automatic tension control systems. BRITISH CELANESE, Ltd. Jan. 20, 1955 [Jan. 22, 1954], No. 1966/54. Class 38 (4). [Also in Group XXXVIII] A tensiometer for controlling tension in a running yarn comprises a member movable about a mean position and subjected to the tension, an electromagnet for opposing the action of the tension on the member and means for supplying energizing current to the electromagnet and for effecting a continual increase or decrease in said current so long as the member is on one side or other respectively of the mean position. Tension in a yarn 3 being stretched in a steam chamber by rollers 7, 4 running at different speeds acts through pulley 19 on the adjustably counterbalanced member 21 which bears armature 26 acted on by electromagnet 41, the current through which is controlled to keep the member substantially balanced. The balancing arrangement comprises a pair of contacts 29, 30 closed spaced on opposite sides of the member and connected to positive and negative potentials, whereby when the lower one is contacted capacitor 37 is charged, thereby raising the anode current of valve 39 which flows through the electromagnet winding until it lifts the member off the stop while if it touches the upper contact the reverse happens. Consequently, a current is maintained in the winding which maintains the member in a null position. In practice, even with a steady tension the member oscillates between the contacts, the current changing between narrow limits as it does so but the mean current is a measure of tension. The position of and distance between contacts 29, 30 can be adjusted. The voltage across winding 41 is compared with that across resistor 45 fed by valve 48 which has a bias which may be varied to determine the standard tension value. The resultant voltage is amplified at 53 and fed to windings 54, 55 of a split field motor which runs at a speed proportional to field current to alter the value of pressure which the automatic pneumatic controller 10 is set to maintain in the steam chamber, whereby to restore the tension to the standard values. Should the yarn break the member stays in contact with 29, thus cutting off the current to relay 61, thereby isolating the motor armature to stop further adjustment of steam pressure and light warning lamp 64. Specification 540,108, [Group IV], is referred to.