GB979832A - Improvements in or relating to yarn clearing devices - Google Patents

Abstract

979, 832. Yarn clearers; stop motions. JUTE INDUSTRIES Ltd. May 8, 1963 [Feb. 24, 1962], No. 7291/62. Headings DID and D1J. A yarn clearing device which is adapted to effect stoppage of the yarn feed upon detection of a fault but not upon detection of a properly completed knot comprises first and second sensing means spaced sufficiently to ensure that a properly completed knot does not cause simultaneous activation of the first and second sensing means but that faults of a certain minimum length cause the two sensing means to be activated simultaneously thereby effecting stoppage of the yarn feed. Yarn 36 is fed past first sensing means comprising a fixed roller 10 and a displaceable roller 11 mounted respectively on support members 12, 14 which lie adjacent the yarn path. The support member 12 is adjustable, a micrometer screw 49 being provided to set the gap between the rollers 10, 11 and the roller 11 is connected to operate a microswitch 20 when displaced by a thickened portion of the yarn. Second sensing means comprising rollers 15, 16 are similarly arranged to operate a microswitch 21. Microswitches 20, 21 are normally open but if closed simultaneously e.g. by a fault of a given minimum length complete a circuit through a relay or relays (Fig. 2 not shown) to energize an electromechanical device 33 operating a yarn cutter 32, the resulting loss of tension in the yarn being used to arrest the yarn feed by a stop motion device not shown. In addition a warning lamp is illuminated. Relay means are included in the electrical circuit to ensure operation of the cutter 32 even if the period of overlap of the sensing means is slight. A bimetallic element is also included to effect deenergization of the device 33 and thus to return the cutter to its normal position after a given period. The electrical circuit additionally includes relays which operate in the event of power supply failure in the circuit of the sensing means to trip out the main driving motor. This prevents continued operation of the yarn feed if the sensing means are inoperative. Slotted guide plates 46 and guide eyelets 45 (Fig. 3 not shown) are provided to guide the yarn into and to maintain it in proper alignment with the sensing rollers. To minimise abrasive wear the eyelets 45 and rollers 10, 11, 15, 16 may be of ceramic material. In an alternative arrangement, the sensing means are used to operate a stop motion directly without the intermediate step of cutting the yarn.