Design And Development Of Conical Hydrostatic Bearing Rotary Table With High Stiffness And High Precision

With the development of manufacturing technology,ultra-precision machining has put forward higher and higher requirements for the static and dynamic characteristics of machine tool axes.As one of the key components of ultra-precision machine tools,hydrostatic rotary table needs to have the characteristics of high precision,high stiffness,good dynamic performance and other excellent characteristics.Therefore,this thesis designed a kind of ultra-precision hydrostatic rotary table with high stiffness conical bearing,and systematically studied its manufacturing process,electronic control system and performance test,which provided theoretical basis and technical guidance for the development of this type of hydrostatic shafting.In this thesis,the method of orifice restriction for conical hydrostatic bearing was firstly determined,and the theoretical calculation and structural design of conical hydrostatic bearing were carried out according to the technical requirements of hydrostatic rotary table.Based on the existing formulas for calculating the stiffness and bearing capacity of cylindrical hydrostatic bearing,a model for calculating the stiffness and capacity of conical hydrostatic bearing was established by using the approximate method.Then,the finite element simulation method was used to optimize the bearing structure parameters,and the simulation results were verified with the theoretical formula.According to the viscous fluid shear force formula,the internal friction moment of the oil film and the average temperature rise of the oil were calculated to ensure the stability of the bearing.In order to avoid the degradation caused by excessive shape variables in bearing operation,the fluid-structure interaction method was used to calculate the shape variables of bearing under three kinds of offset conditions.After completing the design of the bearing,in order to ensure the precision of control system,this paper determines the driving mode of the rotary table as the motor direct drive,and selected the motor,circular grating,driver and other components,and used 3D modeling software to complete the design of the overall structure of the rotary table.In order to ensure the high precision of rotating motion,the machining process was designed for the bearing parts and other parts of the table,and the high-precision machining,manufacturing,installation and adjustment of it were completed.This paper designed and studied the electronic control system of the rotary table,designed the overall circuit and divided circuit of the electronic control system,and builds the physical control system.In addition,based on C++ language,the control interface of the table was designed,and the S-curve control of the motor was also researched.Finally,the feedback structure of the double reading head was analyzed.After the development of the hydrostatic rotary table,the measurement experiments of bearing capacity,stiffness and rotary precision were designed and carried out.The bearing capacity and axial stiffness of the rotary table were measured by partial loading method and high precision inductance probe.After using the improved inversion method to complete the measurement experiment of the rotary precision,the rotary error of the rotary table was analyzed,and an attempt was made to improve the rotary precision.