Performance Analysis And Optimization Design Research On Upper Hook Mechanism Of Knot Netting Machine

The upper hook swing mechanism is an important part of the knot netting machine,its performance will directly affect the performance of the machine and the meshes quality.The upper hook swing mechanism is taken as the research object,analyzing the mechanism performance to explore the factors that cause poor motion stability of the upper hook swing mechanism,and the optimal design is carried out based on the results.In order to optimize the cam profile of upper hook swing mechanism,the principle of fuzzy comprehensive evaluation is applied to determine the upper hook swing mechanism cam curve,and optimized it with the principle of amplitude modulation.Meanwhile,in order to improve the mechanical performance and transmission performance of the upper hook swinging mechanism,the NSGA-? genetic algorithm is applied to the multi-objective optimization of the upper hook swinging mechanism.The main work and conclusions are as follows:Firstly,analyzing the principles of knot netting machine and the upper hook swing mechanism.Using Creo to perform three-dimensional model of the upper hook swing mechanism.Analyzing the upper hook swinging mechanism in ADAMS to find out the main reason which cause the poor motion stability is the upper hook swing cam profile curve is not smooth.Secondly,using fuzzy comprehensive evaluation principle to determine the modified sinusoidal curve as the optimal curve of the upper hook swing mechanism cam.In order to further improve the motion performance of the mechanism,the maximum uninhibited rigid velocity,acceleration and leaping of the modified sinusoidal curve are optimized using the principle of amplitude modulation.Using ADAMS to design the profile curve of the upper hook swing cam.The optimized cam is assembled into the upper hook swing mechanism and kinematics simulation analysis is performed.Simulation results show that the optimization of the upper hook swing mechanical cam is rationality and effectiveness.Thirdly,to improving the mechanical performance and transmission performance of the upper hook swing mechanism,taken the maximum normal force between camand roller,the minimum transmission angle of the linkage and the maximum pressure angle of the cam as the optimization goals,established a multi-objective optimization mathematical model for the upper hook swing mechanism.Using NSGA-? genetic algorithm to solve the mathematical model of multi-objective optimization,obtained a Pareto optimal solution set,and then determine a set of optimal parameters.Analyzing the results of fore-optimization and post-optimization in MATLAB to verify the feasibility of this optimization method.Finally,using ANSYS Workbench to analyze the performance of the major transmission parts-spindle and big gear of the upper hook swing mechanism to verify that they meet requirements,and performances are stable during the movement.Physical prototype to verify the optimized upper hook swing mechanism.The results show that optimized upper hook swing mechanism meets working requirements,compared with the structure of fore-optimization,the motion stability of the mechanism was improved.In summary,in this paper,analyzing the upper hook swing mechanism of knot netting machine,optimized from both the upper hook swing cam and the upper hook swing mechanism.Mechanism motion smoothness,the mechanical performance and transmission performance were improved.