Design And Knotting Experiment Research On Cordlock-winding Mechanism Of Knotter

Aiming at the problems that the rope is wrapped around the knotter hook and the hook clamp has deformed in the process of D-knotter knot-tying,the non-uniform cubic B-spline curve modeling method and the reliability design method based on the cumulative damage theory are used to improve the design of the k cordlock-winding mechanism of knotter.The motion simulation of rigid-flexible contact interaction between the rope and the actuators of D-knotter is used under the environment of ADAMS,in order to verify the rationality of reliability design of cordlock-winding mechanism of knotter.Knot-tying orthogonal test with three levels and four factors is conducted on the test bench for knotting tying continuously.The main works of the paper can be summarized as follows:(1)The surface design of knotter hook: The longitudinal cross section profile of the knotter hook is characterized by nonuniform cubic B-spline curve modeling method.The curve of the longitudinal cross-section profile of the knotter hook is compared with that of the three-dimensional knotting model.The difference in the rate of change of radian is 0.05,which indicates that this method is feasible.The non-uniform cubic B-spline surface function of the surface of the knotter hook is established,and the non-uniform cubic B-spline surface of knotter hook is displayed under tne environment of C++ OPENGL.The requirement of the rope can not wrapped around the boss of knotter hook is got through the analysis of the force when knotter hook knotting,and the non-uniform cubic B-spline curve modeling method is used to improve the design of the knotter hook surface.(2)The reliability design of hook clamp based on the cumulative damage theory: The stress analysis of hook clamp is created according to change of rope tension in the process of forming knots.The static force analysis model of the hook clamp is established by ANSYS finite element software,and the dangerous position of the hook clamp is got by loading and solving.Fatigue analysis of dangerous section of hook clamp is established using fatigue analysis module in ANSYS after determining the dangerous cross section.The fatigue analysis results show that the fatigue loss coefficient of hook clamp is 1.87476 after 100,000 cycles of loading.The minimum cross-sectional area of the hook clamp is taken as the optimized objective function to establish the reliability model of hook clamp based on the strength-stress interference theory.The optimal solution is as follows: the length and width of rectangular cross section are 6 × 6,and the material is 20 CrMnTi,and ANSYS fatigue analysis results show that the load loss coefficient of hook clamp is 0.79256 after 100,000 cycles of loading,the hook clamp does not fatigue failure.(3)Dynamics simulation of cordlock-winding mechanism of knotter driven by double discs: The dynamic model of the rigid-flexible contact between the cordlock-winding mechanism of knotter driven by double discs and the rope is established to analysis the process of knotting tying.which shows that the improved winding mechanism is more reliable.The 16000 knot-tying test is carried out through the the performance test and the reliability test bench of the knotting device,the test results indicates that knotting tying action of the improved cordlock-winding mechanism is reliable.The rope does not slide upward along the surface of the knotter hook。(4)The orthogonal fatigue test of cordlock-winding mechanism: The Knotting orthogonal fatigue test of improved cordlock-winding mechanism is conducted,and the spindle speed of knotter,the rope diameter and the pulling force of the rope are respectively taken as test factors.The installation section distance between the hook clamp and the knotter hook is measured to analyze whether the hook clamp is deformed.The results show that the installation section distance is 0.52 mm after the 16000 knot-tying orthogonal test and is consistent with the fatigue analysis of ANSYS.