The force acting on the yarn axis is called yarn tension. The yarn segment between the front roller and the guide hook is called the spinning segment. The strength of the yarn in the spinning segment is called the spinning strength, and the tension of the yarn in the spinning segment is called the spinning tension. In the spinning process, if the yarn strength at a certain section is less than the tension acting on it, the broken ends will occur, so the fundamental reason for the broken ends is the contradiction between strength and tension.
Because the average value of spinning tension is much smaller than the average value of spinning strength, there is little chance of breakage under normal production conditions. Although the spinning tension and strength fluctuate according to their own laws, breakage does not necessarily occur in most of the time. When the tension acting at a point on the yarn at a moment is greater than the strength at that point, the breakage occurs, which indicates that the breakage mainly occurs at the crossing point of the wave crest and trough in the fluctuation of tension and strength, rather than depending on their average value.
Because in actual production, the average tension is always smaller than the average strength, otherwise spinning can not be carried out. Because of the fluctuation of tension and strength, when the average yarn tension increases and the average tension decreases, and the values of both are close, the probability of peak and trough crossing, that is, the probability of breaking ends, increases. If the fluctuation range of tension and strength is small, especially when the peak value of wave with higher tension is reduced or the trough value of wave with lower strength is increased, even if the average value of both is close, the stability of breakage rate can be guaranteed, and even the breakage rate may be reduced.