Static And Dynamic Optimum Design Of Transmission And Executive Device Of Jacquard Machine

Jacquard machine is a kind of common textile equipment,which is mainly composed of symmetrical distribution of the center crank slider mechanism as the transmission device,lifting knife as the executive device.Optimizing the tolerance distribution of the transmission device and reducing the deflection of the actuator are of great significance for improving the transmission precision,the accuracy of the electronic needle selection device and the quality of jacquard fabric.In this paper,the implementation device is modeled by NURBS method and static structure optimization design is carried out by combining variable section beam theory and finite difference method.Secondly,the flexible body-clearance model is established,and the rigid-flexible coupling model considering the clearance of the moving pair is analyzed.Based on this,the multi-objective tolerance optimization design model is constructed and solved.The main research contents of this paper are as follows:(1)Related methods of NURBS modeling were studied.Based on the original broach model,cubic NURBS curves were used to improve the bottom end face and side shape of broach.The numerical representation of NURBS curve equation and inverse control point algorithm are included,and the correlation modeling method of side curve equation and cross section curve equation is described.(2)Build the mathematical model and optimization method of broach static structure optimization.Based on the NURBS method,a parameterized model was built,and the control points of side curves were selected as design variables.The bending moment function and moment of inertia function of broach model were deduced and solved by using the variable section beam theory and finite difference method,combined with the input design variable and control point inverse algorithm,and the nonlinear constraint function was constructed.Based on the requirement of minimum mass,the mathematical model of static structure optimization is established and solved.By equivalent the variable section beam to the constant section beam and finite element method,the accuracy of the method for solving the maximum broaching deformation in this paper is verified.(3)Build the dynamic tolerance analysis model of the transmission device under the flexible body-clearance model.The traditional rigid body model,the kinematic pair clearance model and the flexible body-clearance model were established respectively.The dynamics of the three models were analyzed,the dynamic characteristic curves of the three models were studied,and the contact collision force between the kinematic pair elements and the deformation of the flexible parts were analyzed.Through the vector ring model,the tolerance analysis model considering the size and geometric tolerance of parts,the clearance of moving pairs and the deformation of flexible parts was established.The Monte Carlo method was used for tolerance analysis.(4)Construct the multi-objective tolerance optimization model of transmission device.The application of manufacturing cost-tolerance model and quality loss cost-tolerance model to jacquard machine transmission was studied,and the objective function of tolerance optimization was established.Combined with the requirements of machining process and assembly,a mathematical model of multi-objective tolerance optimization was established.NSGA-II algorithm was used to optimize the tolerance design of a jacquard drive device,and the optimized tolerance distribution scheme was obtained.