Abstract:

In order to investigate the influence of yarn guide bar on unwinding tension of roving as a function of its installation so as to reduce the unexpected drafting on roving while unwinding and spinning, the roving unwinding tensions were tested when varying the guide bar installation parameters such as the height of installation position, the gap between guide bar and roving, guide bar diameter, types of rotation of the bar, etc. The results demonstrated that the parameters have remarkable influence on unwinding tensions of roving. The optimum guide bar installation parameters were obtained as follows: the height of installation position should be at 1/3 above the bottom of roving bobbin or flush with the bottom, the gap between guide bar and roving as large as possible, the guide bar diameter as fine as possible provided that it can bear the unwinding tension of roving, and transforming the guide bar from fixed type into rotating type makes the fraction between roving and guide bar change from curved surface friction to rolling friction.