Dynamic Characteristics And Reliability Analysis Of A Four-bar Weft Insertion Mechanism With Clearance Space

As one of the main types of weaving equipment,rapier loom has an irreplaceable position in shuttleless looms due to their widely used and good overall mechanical properties.The weft insertion mechanism is one of the key components of the rapier loom.The dynamic characteristics of the weft insertion mechanism affect the production efficiency and product quality of the rapier loom.There is a big gap between domestic rapier looms and foreign rapier looms in working accuracy and reliability.In this paper,the spatial linkages weft insertion mechanism is taken as the research object.The motion characteristics of the weft insertion mechanism,the influence of error factors on the motion accuracy of the mechanism,and the kinematic reliability and dynamic reliability are systematically studied.The main works are as follows:Firstly,the kinematics model of the weft insertion mechanism is established by the dual quaternion,and the linear relationship between the included angle of the mechanism and the output swing angle is derived based on the kinematics results.According to the technical requirements of the weft insertion mechanism,the influence curve of the mechanism angle on the kinematics index is simulated by MATLAB.On this basis,the characteristic included angles are selected and the influence of mechanism parameters on kinematic characteristics is analyzed.Then,the kinematic model of the angles' parameters is transformed into the kinematic model of the rod lengths' parameters by numerical transformation.Combined with the integrated rod length error model,gap model and probability theory,the kinematics reliability model of the weft insertion mechanism which is conducive to computer programming is established.After selecting the allowable error size,the mechanism's displacement reliability,speed reliability,acceleration reliability and the influence of the gear transmission system on reliability are analyzed.Finally,based on Lagrange equation,the dynamic model of spatial four-bar weft insertion mechanism is established,and the variation regularity of the driving torque in one cycle is analyzed.The dynamic error model is deduced by using the established integrated error model and the dynamic model.The dynamic reliability model is esta-blished by a second-order moment method,and the variation regularity of the driving torque reliability with the spindle rotation angle is analyzed.Those results provide a theoretical basis for the reliability optimization design of the weft mechanism.