Kinematics Analysis And Cam Redesign Of Comprehensive Selection System Of Dobby

As the main shedding device in the weaving process,the dobby has been used more and more widely in modern looms.As the core component of the dobby,the heald selection system directly affects the stability,reliability and weaving quality of the loom’s operation process.This paper takes the heald selection system of the rotary dobby as the research object,and studies and analyzes the heddle selection system of important components that affect the work of the dobby.Based on the principle of high pair and low generation,the movement of the conjugate cam and the swing arm is simplified to the movement of the crank and rocker,and the movement of the iron-absorbing pendulum and the signal pendulum is simplified to the movement of the crank slider.In order to improve the reliability of the mechanical movement of the rotary electronic dobby,the kinematics analysis of the selection system is carried out.The operation mechanism of the selection system is studied in detail.Based on the overall analysis method and the complex vector method,the key components are replaced with high pair and low pair.The kinematics model of the dobby selection system is established and kinematics analysis is performed.Using VB.NET for programming,the law of angular displacement,angular velocity,and angular acceleration of each component with the rotation of the active cam is obtained,and the numerical solution of the law of motion of the iron-absorbing pendulum is realized.The Solid Works software is used to establish a threedimensional model of the selection system,and the motion simulation of the motion law of the iron-absorbing pendulum rod is carried out through Solid Works Motion,and the simulation results of the motion law of the iron-absorbing pendulum rod are obtained.Compare the numerical solution results of the motion law of the ironabsorbing pendulum with the simulation results to verify the correctness and reliability of the mathematical model and the motion law.The kinematics of the iron-absorbing pendulum bar is not ideal due to the cam contour line obtained by surveying and mapping,especially the sudden change of speed and acceleration and obvious fluctuation.For this reason,a redesign method of cam contour is proposed.In order to redesign the contour line of the selected heddle cam,the 7th degree polynomial and the cycloidal motion curve are selected as the motion law of the motion section of the iron-absorbing pendulum rod,and a cam that meets the working requirements is designed.The correctness of the design method is verified.From the perspective of mechanism dynamics,explore the intrinsic characteristics of the dobby mechanical selection system.A nonlinear dynamic model is derived for the hedging selection system considering the flexible effect,and the corresponding solution method is studied using the second-order Runge-Kutta method,and the specific analysis steps and calculation process are given;the cam profile pairing hedging system is explored The dynamic behavior of the iron-absorbing pendulum is affected,and the dynamic behavior of the iron-absorbing pendulum is obtained.Combining the principle of the cooperation between the dobby and the loom,a performance test bench for the dobby selection system was designed and developed.The dynamic behavior of the iron-absorbing pendulum rod driven by the heddle selection cam of the dobby is studied experimentally,and the qualitative description method of the vibration response form of the dobby hedging system is obtained by using the experimental method.The experiment collects the vibration response signal of the dobby,verifies the theoretical analysis results,and provides the experimental basis for correcting the built model and verifying the correctness of the theoretical calculation.