Mathematical modeling of weft yarn tension in pirn winding

Abstract

Pirn winding is an operation of winding yarn from supply yarn package onto pirns which are used for shuttle weft insertion. Firm and coherent winding tension is required to maintain in the pirn winding process to withstand the high forces produced by the deceleration of the shuttle at the end of each pick and to avoid permanent strains in yarns which will appears as fabric defects in weaving. The package size and its diameter vary due to subsequent winding of pirns. Hence the balloon effect varies and caused to change the thread tension at the winding point of the pirn. The thread tension variation is considerably significant from the first pirn wound from a package to the last pirn wound from the same if no tension controlling mechanism is devised. Placing dead weights on the disc tension controller which adds a tension to take off tension may help to compensate the yarn tension variation to some extent to combat with this problem. However, this is a stepwise manual compensation technique which needs the correct timing of compensation to avoid significant tension variations in pirn windings. The author attempted to theoretically analyze the tension variation in the yarn path of the pirn winding machine and theoretically model the tension variation with and without deadweight placement on the tensioners. Author also verified the accuracy and the validity of the model developed through the experimental results obtained at different locations along the yarn path.