Analysis And Optimization Of Kinematic Characteristics Of High-speed Electronic Dobby Lifting Mechanism

The rotary electronic dobby machine is a key supporting device for high-speed rapier looms and air jet looms.It has an important influence on improving the working efficiency and fabric quality of the looms.This paper takes high-speed electronic multi-arm devices as the research object,from kinematics,The dynamics and opening process are used to study the modeling,simulation analysis and optimization methods of the comprehensive mechanism.The main research contents and conclusions are as follows:(1)Starting from the configuration of the rotary shifting mechanism,the inverse law,analysis and design model of the rotating motion mechanism of the fixed cam-link is established.The characteristics of the motion of the variable speed output are analyzed and the model of the uniform motion of the constant velocity is proposed.From the perspective of the opening process,the relationship between the rotary shifting mechanism and the lifting arm is analyzed.The design method of the rotating shifting mechanism is discussed by using the simple harmonic correction law and the mechanism evaluation.The angle parameters of the multi-arm input shaft corresponding to the best fitting are determined.For 60°,the lifting arm has a rest time of about 120° with respect to the main shaft of the loom.The conjugate cam profile and evaluation indexes meet the design requirements,and the mechanism has good force transmission performance.(2)Di(?)ing the dynamic characteristics of the multi-arm lifting mechanism from the perspective of dynamics,establish ing the dynamic model of the multi-arm lifting mechanism based on the Lagrange method,and analyzing the collision force between the conjugate cam and the roller of the rotating transmission mechanism when the shifting motion law is different.The influence of the dynamic response characteristics of the heald arms and the eccentric link on the opening process of the loom,the impact force of the cam mechanism designed to determine the simple harmonic and cycloidal correction constant velocity motion are concentrated in the constant velocity section,and the simple harmonic correction isotonic motion law The maximum collision force is smaller than the cycloidal correction constant velocity law,which is beneficial to reduce the warp yarn breakage rate.The dynamic response characteristics and theoretical values of the eccentric connecting rod and the lifting arm are basically the same,and the cycloid correcting the isokinetic motion law The static time is longer,and the eccentric link has smaller fluctuation error,which is beneficial to weft insertion and reduce vibration shock of the mechanism.(3)Studying the motion characteristics of the multi-arm lifting mechanism from the opening warp tension,establishing the warp tension and back beam compensation model of the double back beam system,analyzing the action mechanism of the shifting motion output difference on the warp tension,and discussing the mechanism characteristics and warp tension.The optimization method of simple harmonic and cycloidal correction for the variation of constant velocity motion parameters and the motion characteristics of the active rear beam compensation results show that the maximum pressure angle,maximum dimensionless velocity,rest time and warp yarn elongation are reduced with the constant velocity section.The compensation characteristics are increased,the mechanism transmission efficiency,the radius of curvature,the maximum dimensionless acceleration and the hop arc reduced.Under the same parameters,the harmonic characteristics of the constant velocity motion,the static time and the warp elongation and the pendulum The compens ation amount is smaller than the cycloid correction constant velocity law.(4)Starting from the process parameters such as weaving speed,fabric load and weft insertion time,it is proposed that the wide-width heavy fabric should be selected with the equal-speed segment of the cycloidal correction constant velocity motion law,and the narrow-width lightweight fabric should be selected with a larger constant velocity section.The simple harmonic correction of the constant velocity motion law,the medium speed medium load fabric should be combined with the process requirements to select the simple harmonic or cycloidal motion law of the constant velocity segment parameters.