GB874888A - Yarn handling and severing mechanism for circular knitting machines and methods - Google Patents

Abstract

874,888. Knitting. BURLINGTON INDUSTRIES Inc. Nov. 27, 1957 [Dec. 6, 1956; April 2, 1957], No. 37047/57. Class 74 (2). Yarn extending over the dial cap of a rotary cylinder machine having individually retractable interchangeable yarn fingers is manipulated whilst being tensioned by suction, the manipulation including the steps of inserting yarn into selected needles and severing yarn, active and/or inactive. When yarns are to be interchanged, compressed air is supplied, via a pipe 72, to a yarnhandling mechanism housed in a block 64. A piston is thereby forced upwardly in its cylinder, to rock a lever 94 against the action of a spring 100 and so release a yarn clamp 98; the blast of air through a jet 76 induces a yarn-handling flow of air into a passage 84; and a jet of air issues from a nozzle 120 to position yarns to be severed by a cutter 172, 174. Thus when, say, a yarn finger 36<SP>1</SP> drops to active position, to introduce a yarn 40, the end of yarn 40 is released by the clamp and sucked through the passage 84 into the exhaust conduit 80 of the yarn-handling mechanism. Immediately thereafter, the yarn finger 36<SP>11</SP>, feeding the outgoing yarn 42, is raised to inactive position. As the cylinder rotates, the ingoing yarn 40 is withdrawn by the needles from under a guide tongue 60, the remaining inactive yarns are held and tensioned by the suction and so are not pulled out with the yarn 40, and slack in the free end of yarn 40 is taken up in the conduit 80. Meanwhile, outgoing yarn 42 has been carried, by the last needle 44<SP>11</SP> to knit it, under the guide tongue 60. As the free length of yarn 40 approaches the cutter, it is yielded up under tension, as necessary, by the yarn handler and, entering the air blast from nozzle 120, is bellied out to extend radially from the needle 44<SP>1</SP>, so that it will be cut as closely as possible to the fabric. The outgoing yarn 42 is carried under the yarn handler and into contact with a guide post, a loop of the yarn is sucked up into the yarn handler, and then the blast from nozzle 120 bellies out that yarn also. The movable blade 174 of the cutter is now closed on the other blade, either gradually or in two steps, so that it cuts the two yarns. The cut end of yarn 40 is exhausted through conduit 80 into a receptacle 230. When, momentarily later, the outgoing yarn 42 is cut, the end extending from its finger 36<SP>11</SP> is sucked up into and remains in conduit 80. The same step of the pattern drum which operates the cutter also causes closing of a supply valve 132 in the air line; but a reservoir 134 maintains the air flow for the interval necessary for removal of the end of yarn 40 and engagement of the end of yarn 42 in the yarn handler. Ultimately, however, as the air supply falls off, the suction of the yarn handler ceases and the mechanical yarn clamp again becomes operative.