The Mechanical Characteristics Analysis And Multi-objective Optimization Of Cnc Planer Type Milling Machine

CNC planer type milling machine is a machine tool for mechanical processing, which is the important equipment in military industry, transportation industry and electric power industry etc. With the improvement of precision requirement on products, CNC planer type milling machine requests better comprehensive performance to meet machining precision of parts. The traditional designed CNC milling machine has heavy mass and don’t give full play to the advantages of the structure, requiring the modern design to optimize the design of its structure. The thesis, taking a domestic company’s CNC planer type milling machine as study object, studies the static and dynamic characteristics of its structure, optimizes its structure. The main contents are as following:Firstly, the 3D model and finite element mode for CNC planer type milling machine are established. According to the original design drawing, it adopts solidworks to establish the 3D model. Analyzing its limit processing condition and adopting the principle of simplified finite element establish its finite element simulation model.Secondly, the mechanical characteristics for key components and the complete equipment of CNC planer type milling machine are studied. The analysis on static and dynamic characteristics of beam, column and the complete unit finds out the distribution of deformation and stress under limit condition; acquires 6 extended modal shape and natural frequency; gets the weak link, and provide support for subsequent structural improvement and optimization.Thirdly, the mechanical characteristics for the complete equipment of CNC planer type milling machine are improved. Find the weak link from the static and dynamic characteristics of the whole machine and improve whole structure of the machine.Fourthly, the mechanical characteristics for key components of CNC planer type milling machine are optimized. According to the result of the static and dynamic characteristics for the beam and column, multi-objective optimization of the six dimensional parameters is solved by combining orthogonal experiment, the response surface model and genetic algorithm. The optimization is multi-objective that includes minimum deformation, maximum first natural frequency and minimum mass. The maximum deformation is almost invariable, the first natural frequency is increased by 5.52% and the mass is deduced by 11.68% after the beam optimum design. The first natural frequency is almost invariable, the maximum deformation is decreased by 4.39% and the mass is reduced by 10.45% after the column optimum design.Finally, the effect of the whole machine performance after optimization of the keyparts is verified. Reset up the whole machine model with optimized beam and column model and analysis the static and dynamic characteristics of the optimized whole machine. Compared with the original whole machine, the optimized whole machine could avoid the resonance. The stiffness in orientation x, y and z is increased by 12.47%, 10.16% and 26.37%. The first 4 natural frequencies are increased by 28.72%, 7.03%, 18.02% and 2.60%. The mass is reduced by 1480 kg, the proportion of the original machine is 5.24%. The static and dynamic performance of the whole machine is improved and the mass is reduced and reach the optimization purpose.