Study Of Static&Dynamic Characteristics And Optimization Of High-speed Vertical Machining Center Worktable System

Worktable system is one of basic components of high-speed machiningcenter, including worktable, guideway, screw and screw-mother, and itwithstands the static load from the processing center as well as cutting load inprocessing. Therefore, it must have sufficient stiffness. In another hand,machining center worktable system’s strength and stiffness properties determinethe processing quality and service life of the machining center, so it is necessaryto analyze the static and dynamic characteristics of worktable system.The research’s target is to design a worktable system with higher static anddynamic performance.Firstly, according to the available worktable structure models on themarket and practical experience, four kinds of worktables with differentreinforcement layout were designed. The3D models of them were established,and then assembled with guideways, sliders, screws into worktable systems inSolidWorks; Combination with the finite element analysis theory, some structuralfeatures of the models are simplyed appropriately so as to establish finiteelement models for worktable systems in ANSYS WorkBench.Secondly, the four worktable systems were carried out static analysis tocalculate the static stiffness of them on each direction. After compration, aworktable system, strength general reinforcement worktable system, was pickedup, which was with better static mechanical properties. On the basis of staticanalysis, the strength general reinforcement worktable system was taken asresearch target to do dynamic analysis. The first-15natural frequencies and modeshapes were obtained to find the system’s dynamic characteristics, it was foundthat its reinforce and screw with weaker stiffness.At last, combination with static&dynamic analysis results, the highernatural frequencies was set as optimization goal to optimize the worktable system structure. On one hand, taking increasing the system’s natural frequencyas objective function and VOLUME as constraints, topology optimization wascarried out for strengthen general worktable system in ANSYS, a new materialsdistribution model was achieved. According to the new model, the thickness ofworktable shell and reinforce need thickening, which would affect the wholestructure of the worktable system, therefore, it was decided to retain the originalstructure of strength general reinforcement worktable system. On the other hand,because topological optimization’s result was not ideal, taking increasing naturalfrequency of the system as the goal again, a new idea was proposed as theresearch object, it was center of gravity-driven worktable system which tookduble-screw trassimision instead of tradition sigal screw trassimition. The twoscrew’s distance in the horizontal was taken as optimization parameter toestablish the worktable’s parametrical model for optimization. Modal analysiswas proceeding to double-screw transmission worktable system with differentparameters, and the one with best dynamic performance was picked up, in whichtwo screws’ distance was310mm, and laid inside guideways. HarmonicResponse was carried out for the optimized model to draw the chart offrequency-amplitude. The chart showed Harmonic Response’s result coincidedwith mode shape.