Analysis and modeling for the dynamics of the nipper mechanism considering jaw’s impacts

Abstract

The comber is very important in the spinning for high quality yarns, in which the nipper mechanism (NM) determines the quality of the yarn it combs. This paper is to connect topology and multi-body dynamics to reveal the principle of impact motion of the nipper mechanism. Firstly, the working process of the NM is analyzed and corresponding kinematic models of work sub-phases are derived. Subsequently, the transition from the work phase of the jaw closed to the opened is studied. The research results show that during the transformation process, the mechanism presented another work phase with multiple impacts, which is the main reason why the NM could not stably clamp the cotton clump and thus affect the quality of the yarn combed by the comber. According to the relative coordinate method, the dynamic model of the NM is set up. Combining the classical collision theory and the restitution coefficient equation, the acquisition of the impact impulse generated at the jaw and the subsequent motion of the mechanism are decided. Finally, the NM in the E62 comber is taken as an example to verify the correctness of the established dynamic model, and the influences of different input speeds, restitution coefficients, and stiffness coefficients of spring on the jaw’s impact are studied. This has certain theoretical value for improving the speed and efficiency of the comber.