Patent GB-823583-A (GB)
Title: Method and apparatus to draw off a fold of welt fabric on a straight-bar knitting machine
IPC: D04B11/32
Filed: 1957-04-25
Abstract: 823,583. Knitting-machines. COBERT, A. J. April 25, 1957 [May 29, 1956], No. 13179/57. Class 74 (2). The fabric take-up mechanism described in Specifications 765,839 and 765,841 is modified whereby the welt wire 250 held between arms 160, 162 suspended from above the narrowing machine comprises a flexible nylon covered wire which prior to the turning of the welt is drawn so as to extend between the arms, and which after the welt and wire has passed between the nip rollers 56, 64, is withdrawn endwise from between the fold of the welt. The drive to the nip rollers is under the influence of a spring 86 the tension of which is varied as the fabric is narrowed so that the draw-off tension imposed by the nip rollers is varied in relation to the width of the fabric. The arms 160, 162 are suspended from the ends of substantially horizontal arms 166, 168 which are pivotally mounted at their rear ends on a shaft 174 and are raised to and lowered from an inoperative position through a magnetic clutch 194 by a drive from an electric motor on the machine. The arms 160, 162 are also pivoted about the end of the arms 166, 168 under the control of a magnetic clutch 228 through link 184 so that the welt wire moves towards and away from the needles. Prior to turning the welt the arms 166, 168 are in a raised inoperative position and the lower end of the arms 160, 162 are positioned inwardly towards the machine so that a button 254 on the end of the welt wire is engaged in a fork 312 of a traversing member 304. The member 304 is in its extreme right-hand position of Fig. 4 so as to engage the button on the welt wire which is in its withdrawn position having been so drawn by wire 260 connected to pulley 266 coupled to a magnetic clutch 278 when it was withdrawn endwise from the fold of the previous welt. The member 304 is then traversed by a chain 316 coupled through chain and sprocket and bevel gearing to a magnetic clutch 354, to draw the welt wire so that it extends from arm 162 to arm 160 in which latter it is held by a catch 286. Sufficient of the welt being knitted the arms 160, 162 are moved outwardly and then lowered by lowering the arms 166, 168. The lowering of. arms 166, 168 actuates a switch 218 controlling the tilting movement of the welt bar as described in the prior Specifications referred to above. The arms 160, 162 are then further moved outwardly to engage the welt and under the influence of spring 242 to continue to draw the fabric from the needles and thereby effect a doubling of the welt. Subsequently the nip rollers 56, 64 are drawn towards the needles by cable 124 under the control of magnetic clutch 134 so that the rollers 56, 64, held apart by solenoid 370, pass above and beneath the welt and welt wire. Release of solenoid 370 causes the rollers to grip the fabric and under control of pawl and ratchet mechanism 72, 70 to commence take up of the fabric. The welt wire 250 is then released by catch 286 and withdrawn endwise from the fold of the welt fabric by wire 260 being wound on pulley 266, and the arms 160, 162, 166, 168 are raised to their inoperative position. The member 304 is also returned to its extreme right-hand position in which it can reengage the end of the wire to reposition it ready for the next welt. The take up of the fabric by the nip rollers is controlled by the spring 86 which engages one end of a permanently reciprocating lever 74. The spring 86 is coupled through lever 88 and cable 94 to a collar 96 on a shaft 92. The position of shaft 92 is adjusted in relation to the width of the fabric by cam mechanism 98, 106 controlled through a rack and pinion 114, 112 coupled to the carrier stop block 120. Consequently adjustment of the carrier traverse by the block 120 increases or decreases the tension in the spring 86 and thereby the pull exerted on the fabric by the nip rollers 56, 64.