An Investigation On The Multi-objective Optimization And Stream Line Field Of The Hydrostatic Guideways

With the increasly requirement of the ultra-precision machine tools in the field of civil, national defense, space science and so on, the demand of machining precision and working performance of the ultra-precision machine tools is becoming more and more rigorous. Though there are factors that will affect the property of ultra-precision machine tools, it mainly depends on the performance of its key components. The guide pairs are the key parts, which will directly guarantee the machine precision of the relative position and relative motion between many moved components. The hydrostatic guide way will usually solve the common problem of friction and vibration, therefore, the hydrostatic guide way will undoubtedly be one of the best solutions of the ultra-precision machine tools’guide way system that should be chosen. In order to satisfy the requirement of high speed, high efficiency, high precision of the hydrostatic guide way, the hydrostatic guide way should have good carrying capacity and stiffness of oil film. The thesis will use the constant pressure, closed, hydrostatic guide way positioning platform as the research object, it contains the following aspects:(1) To begin with, comparing the performance of constant pressure, constant flow and closed, open hydrostatic guide way, we finally chose the constant pressure and closed hydrostatic guide way. We emphatically analyze the static properties of the symmetric and asymmetric structure form in the closed hydrostatic guide way. Then we get the deflection’s influence law of L to guide way workbench, in which L stands for the working arm span of the left and right side of two groups of oil cavity.(2) According to the technology index of the ultra-precision machine tools studied of the background, we have make structure design and calculation to the constant pressure closed hydrostatic guide way. What’s more, we design the three-dimensional structure model by using of the software called solidworks. It has a powerful function of three dimensional modelling.(3) Using the guide way’s overall structure model as the research object and comparing with the orthogonal experiment design method, mathematics comprehensive evaluation method and the finite element method, we comprehensively analyze its static property. Then we can identify the key factors and the non-critical factors that will influence the guide rail positioning platform’s overall deformation. Eventually we multi-objective optimize the constraint which is based on quality, structural stiffness and strength. Our purpose is to improve the performance of the bearing, stiffness and stability performance of the hydrostatic guide way platform.(4) By adopting fluid dynamics finite element analysis method to build an all-parameter three-dimensional entity model of the oil film between the guide rails, this thesis discovers the distribution of the static pressure of the oil film and the law of flow distribution and velocity of the hydraulic oil. Besides, this paper also distinguishes how the load-bearing performance and stiffness of oil film between the guide rails are influenced by the differences in the depth of oil cavities and oil grooves, the thickness of oil films and the input pressure parameter of oil intake hole.(5) The static pressure of oil film is first obtained based on fluid simulation calculation method. Then, according to the fluid-structure interaction calculation method, the author calculates the elastic deformation amount of the guide rail board under the static pressure of the oil film. After the quantitative analysis of the deflation amount of the board, this paper finally obtains the regular of how the board deflation caused by the static pressure of the oil film influence the straightness of the guide rail.