Dynamic Optimization Design Of Horizontal NC Lathe Structure Based On FEA

With the increasing requirements on machining products quality, the dynamic performance of the machine tool structure need higher and higher requirements. It’s necessary to analysis on the static stiffness and dynamic performance of the important bearing parts; establish and optimize the finite element models of whole machine to improve its performance on the process of design of machine tool. In that case, the paper using the method of the finite element to analyze NC machine tools and optimize the structure of the bed. Using variation analysis method to analyze parameters and sensitivity of the lathe. According to the results of multi-target size optimization and topological optimization identify the optimization scheme. Performance is optimized by establishing the model of the whole machine concerning joint surfaces. Relevant theories are verified in practical experiment on CKL630D.The paper firstly expounds the related basic theory. Recommend the finite element ideology classify the finite element method, procedure of applying finite element are given and the concept and algorithm of optimization design is illustrated.Operating condition of NC Machine are analyzed, including maximum torque calculation, cutting force confirming and resistance analysis. To establish the simplified mechanical model, to solve the mechanical model by theoretical calculation.The lathe bed plays a very important role which is the main bearing member of NC machine tools. Static and dynamic characters of the lathe bed directly influence processing precision of the machine.3-D model of the machine framework is built by using3-D CAD software. The finite element method is exploited to carry out static analysis and modal analysis by using ANSYS. Strength and stiffness of the machine framework is calculated in static analysis, the inherent frequencies and relative vibration modes of the first6ranks of modals of the machine framework is obtained using modal analysis. Variation analysis is applied for size and topological optimization in order to optimize the structure of the lathe bed. The rib size is set by multiple parameters. Multi-target optimization is based on parameter and sensitivity analysis. Topological optimization is achieved using constraints of minimum compliance. New lathe bed structure based on the topology optimization results in its internal rib arrangement. Final design of bed structure is decided by comparing these two optimization results. Considering the influences of joint surface on dynamic modeling and analysis. Equivalent kinematic models of the guide and the bolt joint surfaces are established. Damping-spring unit was adopted to simulate joint surface. Parameters of each joint surface are calculated based on Hertz law and integration method.Dynamic performance of the whole machine tool concerning influences of joint surfaces is obtained through finite element analysis. Dynamic performance is optimized by changing the number and the diameter of bolts. Due to the optimization, weight of the whole machine tools is reduced by8.6%with the same stiffness and the inherent frequency is increased.