Rieter

Cop shape

Index

The cop, the typical package shape on the ring spinning machine, consists of three clearly distinguishable buildup sections (Fig. 44):

  • the lower, rounded base (A)
  • the middle, cylindrical section (Z) and
  • the conical nose (S).

The package holder is a tube made from paper, cardboard or plastic, of which some 10 mm at the top and bottom remain uncovered by yarn, and being slightly tapered fits exactly on the spindle. The specific shape of the cop is created by the tapered application of a large number of individual layers of yarn, one on top of the other (see  Technology of Short-staple Spinning). Each of these layers consists of a main winding and a cross winding. The main winding, which primarily has to take up the yarn, is usually formed as the ring rail slowly rises, the wide open cross winding during the rapid lowering of the ring rail. Since the cross windings are laid diagonally between the main windings, they isolate the latter from each other. This prevents entire layers from being pulled off during unwinding of the cop in downstream processing (Fig. 45). Compared with other types of winding, such as parallel winding ( roving frame), the disadvantage of cop winding is that it requires a more complicated mechanism and winds the yarn with continuously changing tension. However, it is ideal for unwinding on the winder, since it permits high unwinding speeds.

Fig. 44 – Cop shape

Fig. 45 – Main and cross windings