Research On Structural Topology Optimization And Bionics Design Of Milling-lathing CNC Vertical Column

As the rapid development of equipment manufacturing technology, the advanced manufacturing technology characterized by digitization and precision, it is developing towards the high efficiency, high accuracy and recombination. The core-competitiveness of advanced manufacturing technology depends on the technical level of CNC. In many different research fields of the high-grade digitally controlled machine tools and key manufacturing, the advantage of turning transforms as milling makes synthesis movement of turning's shaft and milling's shaft to combine a synthetical movement. Moreover, milling-lathing CNC accomplishes the aim of high-speed and combined machining with completing all manufacturing procedures when complex part are champed.Milling-lathing CNC vertical column, as the basic component of structural system, its stiffness and inherent frequency has great influences on the part of the surface qualities and noise of manufacturing process.Therefore, in this paper, using computer modeling and FEA technology, aimed at the high-mechanical capability request of mill-turning CNC column, an integrally optimum design method was proposed for vertical column structures based on topological optimization and biological structure design. During the research process, this paper studied some fields of vertical column as following: working loads, static and dynamic characteristics, multi-objective topological optimization, structure biological design.The results obtained by these work on vertical column can provide an idea for optimum structural design. The research contents are as follows:(1) According to the actual working situation of conpound machining center,firstly, the analysis was premised on the basis of milling HT300 material to calculate the conpound machining center two kinds of working condition that were the maximum-working load position and typical machining position. Then the finite element model of vertical column was modeled to simulate its static and dynamic characteristics under max-working load position condition. According to the static and modal simulation analysis, vertical column's max-deformation took place in top position of the left column, total max-deformation was 24.82 um, and the direction Y was most affected on max-deformation. Besides, the sixth-order inherent frequency and vibration modes were calculated, and on the basis of harmonic response analyse to forecast the displacement of vertical column would be happened obviously when the excited frequency was 80 Hz.(2) Firstly, based on the variable density method, the mathematical model of multi-objective topological optimization of vertical column was established.Afterwards, using the HyperWork software to built the finite element model of primary iteration that would be calculated with topological optimization of vertical column. By applying two kinds of static state sub-objectives to the design domain,and a dynamic low-order-frequency response was restricted. Finally under multi-objective topology optimization, the load transfer path of the column structure was obtained. Based on topology optimization results, This chapter proposed the suggestion that keeping the column shape unchanged to redesign the internal structure by structure biological design.(3) According to the optimization suggestion of the design direction, the vertical column internal structure was designed from the structural similarity of the vertical column and hollow-stem plant, and to analyse the structure features of the ideal modal of the plantain petiole, and calculating its hexagonal grid element that was largely responsible for the plantain petiole structure. Then three kinds of deriving structure of the plantain petiole was drawn, and three models of bionic structure bulkhead were designed and confirmed. Based on the topology optimization result,The vertical column internal structure was designed by distinguishing the density and gradient with solar stiffened plate and cross stiffened plate.(4) According to the static and modal simulation analysis of the bionic column and the finite element analysis, under the same loads and constraints, the SME(Specific stiffness structural efficiency ) of three bionic column structures improved respectively 85.94% ?82.53%?89.60% compared with prototype design, and the over-all mechanical properties of three bionic columns are improved obviously.Furthermore, compared with prototype design of vertical column, the total max-deformation of bionic design C was reduced by 48.35%, and the deformation of error sensitive direction Y was reduced by 70.41%, and the static and dynamic characteristics of bionic design C was most excellent in all of the three bionic columns, and the average increment in sixth-order inherent frequency of vertical column was 17.50%, and the max-deformation in in sixth-order inherent frequency of vertical column was smaller. Therefore,the Bionic design of the column improved the material utilization,and the SME is increased markedly, the first order frequency is increased and the dynamic and static characteristics are also improved.