Static And Dynamic Characteristics Analysis And Structural Optimization Of Horizontal CNC Lath

With the modern manufacturing industry on the production efficiency and precision requirements continue to improve,prompting CNC machine tools to the direction of high speed,high precision and high efficiency.The structural characteristics of CNC machine tools determine the impact of the machine tool’s static and dynamic characteristics on machining efficiency and accuracy.Relying on the designer’s experience or analogous development can no longer meet the requirements of modern design,so the use of modern design methods combined with optimization design theory to analyze and improve the structure of machine tools in order to improve the overall static and dynamic performance of machine tools to meet the needs of modern manufacturing industry has become an urgent problem for universities and enterprises to solve.In this paper,a horizontal CNC lathe is taken as the research object,based on the finite element method,the static and dynamic characteristics of the whole machine and key components are analysed,the weak points of the machine are identified according to the results of the static and dynamic characteristics analysis,and on this basis,the structure of the bed,bed saddle and spindle box is optimised and designed.The main research elements of this paper are as follows.(1)The three-dimensional solid model of the whole machine and key components of the horizontal CNC lathe is established,and the model is reasonably simplified according to the St.Venant principle.The finite element program ANSYS workbench imports the three-dimensional solid model,and the finite element pre-processing of the whole machine and key components is carried out according to the actual working conditions,including mesh division,contact surface setting,load loading,and boundary constraints,etc.The magnitude of the cutting force of the lathe is determined according to the empirical formula calculation method.(2)Using the finite element analysis approach,the static and dynamic properties of the horizontal CNC lathe and its essential parts are examined.Research the static stiffness and displacement of important components and the entire machine,as well as their static stiffness and displacement.Get the deformation and stress distribution of the key components and the entire machine under static load.To determine the corresponding first six natural frequencies and vibration mode characteristics,as well as to pinpoint the machine tool’s weak points,the dynamic properties of the entire machine and its essential components are examined.The bed,bed saddle,and spindle box are ultimately chosen as the parts that need to be improved once the findings of the static and dynamic characteristics study have been integrated.(3)Based on the optimization design theory,the structure of the bed and the bed saddle are optimized.An optimization method combining sensitivity analysis and response surface modeling is developed in response to the findings of the static and dynamic features investigation of the bed.The four essential dimensions of the bed wall thickness and rib size are determined using the sensitivity analysis method as optimization parameters.The response surface model of the machine bed is built using the best-filled space design method(OSF)and Kriging function method.A multi-objective genetic algorithm solves the response surface model(NSGA-II).The variable density topology optimization method is used to optimize the design of the bed saddle,and the model is reconstructed based on the bed saddle structure obtained after topology optimization.At the same time,the rib plate layout is designed to ensure that the static and dynamic performance of the bed saddle meets the design requirements,to ensure that the dynamic performance of the optimized bed saddle is improved while achieving the goal of lightweight.(4)Aiming at the problem that it is difficult to obtain the explicit functional relationship between design variables and performance objectives in the design optimization of the spindle box,a joint optimization platform of Solid Works and ANSYS workbench is built based on the Insight software.The optimal Latin hypercube experimental design method(Opt LHD)is used for experimental design.According to the experimental verification point,the RBF neural network model of the main axle box is constructed and its accuracy is verified.The combination optimization strategy of the multi island genetic algorithm(MIGA)and sequential quadratic programming(NLPQL)is used to optimize the RBF neural network model.The results show that the mass of the optimized headstock is reduced by 12.89% on the premise of ensuring the mechanical properties of the headstock,and the expected effect of the optimization is achieved.