Analysis And Elastic Dynamics Simulation Of Spatial Four-bar Linkage Weft Insertion Mechanism With Clearance

Weft insertion mechanism is one of the most important parts of the weft insertion mechanism which is generally placed in high-speed location of the rapier loom. Kinematic accuracy of weft insertion mechanism directly influences the effect of weft insertion rapier loom. At present, there is still a large gap between domestic high-grade loom and advanced loom in foreign because of the defects in the aspects of weft insertion mechanism. So the research on the performance of weft insertion mechanism to improve the processing quality of domestic textile machinery and international competitiveness is particularly urgent.In this paper, based on the backward status of the whole performance of domestic high-grade loom, kinematics analysis and dynamics simulation of four-bar linkage weft insertion mechanism with clearance are carried on through theoretical analysis and virtual prototype test in the condition of considering rigidity and the elasticity. The main work and results are summarized as follows:1) The kinematics model of spatial four-bar weft insertion mechanism is established. Kinematics simulation is carried on with the programming and the kinetic characteristic curves of the sword belt are generated in MATLAB. Based on the continuous-contacting model and the theory of equivalent rod length, considering the the influence of clearance on the motion, the kinetic characteristic curves of spatial four-bar linkage weft insertion mechanism with clearance are obtained and the motion curves of the sword belt under various conditions are compared and analyzed in this paper.2) Three-dimensional model of the mechanism in research is established by UG. In combination with ADAMS, adding kinematic pairs to the mechanism, dynamics simulation of the rigid body is conducted and the kinetic characteristic curves of the mechanism without clearance and mechanism with clearance are obtained in the ADAMS simulation environment. The impact of clearance on the kinetic characteristics is analyzed and compared with the kinematic characteristics curves in MATLAB.3) Based on the improved Hertz theory and considering flexibility of the component, the rigid-flexible coupling model of the mechanism is established and the dynamics simulation is completed by the combined use of ANSYS and ADAMS. Then the influence of the clearance between the connecting rod and the sector gear joint and the flexibility of the forked frame and the connecting rod on the output characteristics of the sword belt is analyzed. The material of forked frame is set in ANSYS, with simulation and analysis in ADMAS, the influence of the material properties of components on the kinematic characteristics and the dynamic characteristics of mechanism with clearance in the condition of considering the flexibility are obtained.4) Dynamic impact model is established by analyzing the common dynamics analysis model, the impact force curve and the contact surface deformation curve of the impact model are analyzed. In the planar four-bar linkage mechanism, two state analysis model is introduced and the dynamic analysis of mechanism hinge link is carried out by the rigid model and MLSD model in the continuous contact model, and the characteristic and difference between the two are obtained.