GB1248844A - Method and apparatus for handling yarn - Google Patents

Abstract

1,248,844. Crimping yarn. DEERING MILLIKEN RESEARCH CORP. 9 July, 1969 [10 July, 1968], No. 34675/69. Headings DID and D1F. A method of uniformly crimping a running strand of thermoplastic yarn comprises the steps of a) continuously withdrawing a yarn strand 21 from a supply source, b) positively feeding the strand into a heating zone 14 to maintain the strand under relatively low tension in the heating zone to facilitate its contraction during heating, c) heating the strand to between its first and second order transition points, and d) pulling the heated strand about a surface 16 of frictional engagement to continuously bend the strand along its length and impose latent stresses therein, while controlling the rate of withdrawal of the strand from the surface 16 to maintain a uniform tension in the strand leaving the surface 16. In operation, yarn 21 is withdrawn from a pirn 24 and positively fed by driven nip rolls 22, 23 to a plate heater 26. On leaving the heater 26, the yarn 21 is bent round a blade member 28 to impose latent stresses in the yarn. The yarn is withdrawn from the blade 28 by a pair of driven tapered nip rolls 32, 34, and is finally wound on a ring and traveller spinning device 30. Situated between the blade 28 and the tapered nip rolls 32, 34 is a tension sensing device comprising a pivoted lever 50 with an eyelet at one end and a weighted spring 54 at the other.- The pivoted lever is biassed for rotation in a first direction and any change in the tension of the yarn causes the lever to pivot and the yarn is correspondingly shifted along the surface of the tapered nip rolls to thereby increase or decrease the rate of withdrawal of the yarn from the blade 28. The nip rolls 22 and 32 and the ring spindle are driven by means of pulleys and belts 36, 38, 40 from a common drive motor 42, the speed of rotation of each being set by selection of the size of pulley. A pneumatic piston-type damping device 58 may be provided to prevent over-correction of the tension by the lever 50.