Modeling And Parameter Optimization Of Key Components In Small Precision Machining Center

Precision,miniaturization and lightweight is one of the development orientations of high-grade equipment manufacturing industry.Due to the high precision requirements and complex structure of small precision optical lenses or electronic components,it is difficult to guarantee the machining quality if they are processed on a general machine tool.Therefore,there is an urgent need to develop a special small precision machining center for achieving the finish machining of sophisticated parts.The guideway and the rotary table are two key parts of small precision machining center,and the core part of them is the precision aerostatic bearing.The parameters of the aerostatic bearing were optimized Based on the theory of gas lubrication.On this basis,this p aper conducted the structural design of the guideway and the rotary table,explored their static performances,and Finally the structural strength of them were checked.The specific research work is as follows:In view of the throttling types used in aerostatic bearing,two throttl ing modes of aerostatic bearing were proposed in this paper,that is,the orifice type and the porous type.Based on the theory of gas lubrication,the mathematical models of aerostatic bearings based on two kinds of restrictors were established and the governing equations of the static performance were obtained.On this basis,the finite element software was used to optimize the parameters of restrictors of the orifice type and the porous type respectively.The effects of the size of orifice,the size of gas chamber,the guide angle of orifice,the layout of pressure-equalizing groove,the size and the permeability of the porous restrictor on the performance of aerostatic bearings were revealed,which laid a foundation for the design of the guideway and rotary table.Based on the parameter optimization of restrictors,the performance of the orifice-type and the porous-type aerostatic guideways was compared,and the superiority in the performance of the porous-type aerostatic guideway was demonstrated.An analysis module of the fluid-solid coupling was built in the Workbench software.The structure and parameters of the aerostatic guide way were determined by optimizing the slider material and the initial gas-film thickness,which ensured the static performance of the aerostatic guide.The static performances of the multi-restrictor aerostatic thrust bearing were analyzed taking the plane-radial combined thrust aerostatic rotary table as analytical model.The influence law of the number of restrictor s on the performance of aerostatic bearings was revealed by numerical simulation.Through comparative analysis,the superiority of the annular porous-type aerostatic thrust bearing was demonstrated,which la id a foundation for the design of rotary table.Based on the optimization of the number of restrictors,the structure of conical thrust aerostatic rotary table was proposed.The static characteristic curves of the conical thrust aerostatic rotary table were obtained by the ANSYS software and they were compared with the static performances of the plane-radial combined thrust aerostatic rotary table.Finally,the optimal initial gas-film thickness of the tapered thrust aerostatic rotary table was recommended.Through the theoretical analysis of structural statics,the mathematic al equation of finite element calculation was introduced.According to the finite element simulation,the deformation and stress of the structural parts of guideway and rotary table in the process of micro-hole machining were obtained taking high-speed drilling as the research object.The rationality of the structure had been verified.