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The Winding Process

  • Continual withdrawl of the yarn from the rotor is ensured by the withdrawl rolls  {a}. Winding up is effected under light tension by rotation of the package {s}, driven by friction from the winding roll, the yarn will in any case run through a thread guide {f} &may additionally pass  : a bow{b} ,a yarn storage device {r} &a waxing device [p]. Waxing devices are used mainly in the spinning of knitting yarns.
  •  The thread guide {f} is arranged to effect crosswise laying of the yarn in the package by means of its to & fro movement.
  • The bow{b} or the store device{r} is needed to even out path length variations, which arise because the length of yarn between the withdrawl rolls & the right or left hand edge of the package is greater than the length between those rolls  & the middle of the package is also constant {in the winding of cylindrical packages} , corresponding curvature of the bow { steep in centre , flatter towards the ends} ensures a constant path length for the yarn.
  • Path-length compensation by means of a bow is , however , adequate only for the winding of cylindrical packages {cheeses} and cones of up to 2 degrees taper.
  •  The bow is no longer enough with larger taper angles.
  • The circumferential velocity at the right hand end is therefore noticeably different from that at the left -hand end. In this case , a yarn store can be used .
  •  The rotation rate of the package is the same at all points of the package, but the package diameter varies significantly from one end to the other .
  • During winding on the smaller package diameter { lower circumferential velocity} ,the lever arm {r} is moved to the right & thereby forms a loop in excess  yarn length {thread reserve}.
  •  As one yarn moves from the smaller to the larger end of the package ( high circumferential velocity}, a greater yarn length is needed.
  • As the lever moves to the left , the loop decreases, i.e. The excess yarn length is released.
  • The yarn store can be eliminated if the speed of rotation of the winding roll can be continually varied to adopt it to the winding diameter of the package.

 

 



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