Thermal Research And Fluid-Structure Interaction Analysis Of High-power And High-precision Hard Turning Hydrostatic Spindle

Turning is one of the most important and the most basic machining methods. Traditional cutting technology cannot achieve high hardness, high strength of material processing, which restricts the development of equipment manufacturing industry in our country. Hard turning technology is an advanced machining technology which can directly to realize the high hardness (55HRC-65HRC) and high strength materials turning, which is as finishing or end processing. Because the hard cutting technology has high turning efficiency, clean processing and high processing precision, hard turning technology are applied successfully which replaces the grinding technology and realizes high strength, high hardness materials processing in the western developed countries. There still exist a big gap between home and abroad about the hard turning technology.Machine tool spindle is a key component of the hard turning machine. Hydrostatic spindle has high rigidity, high rotary precision and high damping characteristics which meets the requirements of hard cutting technology. But the research on hydrostatic bearing load-bearing characteristics, temperature characteristics and rotation error measurement technology is still insufficient. Based on the hydrostatic spindle system as the research object, hydrostatic bearing pressure, temperature, flow field distribution and stiffness are studied respectively through the classic numerical calculation and finite element analysis method. In addition, the technology of the rotation error measurement is studied.According to classical design theory of hydrostatic bearing, the flow characteristics,stiffness and the average temperature rise of radial and thrust bearings are studied through numerical calculation.Based on ANSYS platform, using the finite element analysis method to realize parametric modeling of the radial bearing and thrust bearing oil film. By FLUENT software platform, the static and dynamic hydrostatic bearing oil film characteristics are analyzed, especially the distribution of pressure field, temperature field and flow field.Radial bearing and thrust bearing stiffness characteristics are studied under different eccentricity condition. Finally, the finite element method is compared with classical numerical calculation method.Based on static and dynamic characteristics study of hydrostatic oil film, the parametric3D entity modeling spindle system has come true.Through the data exchange among ANSYS, FLUENT and Workbench, the characteristic of the spindle unit is studied with the fluid-structure interaction method and analyses the influence of hydrostatic bearing oil film pressure field distribution on the oil film thickness, the hydrostatic bearing oil film internal friction and the temperature characteristic of the spindle system.The correctness of the finite element model is verified through the temperature rise experiment.With the self reference method which takes the online finishing test bar as the datum rather than the standard test bar, the rotation error of the hydrostatic motorized spindle is measured. Based on frequency domain three-point method,the rotation error and roundness error is separated from the one-way runout error. The spindle rotation error and roundness error are evaluated with the least square method.