Analysis Of Thermal Characteristics Of The Ultra-precision Diamond Lathe

Ultra-precision manufacture equipment is prerequisite for the development of Ultra-precision manufacture technology. Domestic and foreign scholars have done a lot of research on the static characteristics, dynamic characteristics and thermal characteristics on the ultra-precision machine tools. The results of the study show that 40%-70% of the machine tools'error is caused by is the thermal deformation of machine tools, so it has a great sense to analyse the thermal characteristics of the machine tools. In this paper, thermal characteristics of an ultra-precision diamond lathe are studied.The spindle adopting aerostatic bearing is the most important component of the ultra-precision diamond lathe.Thermal conductivity model of the gas film in the aerostatic bearing is established, and the temperature rise under different revolution is calculated in this paper. The heat convection coefficient in the air-gap of aerostatic bearing and on the other outside surfaces of the spindle are calculated. Finally the steady-state temperature field and thermal deformation under different revolution of spindle are analyzed by ANSYS, and temperature curve and thermal deformation curve under different spindle revolution are plot. The result shows that the stuck of spindle won't happen when the revolution reaches the highest design revolution.To reduce the influence of thermal deformation of hydrostatic guide to the lathe, the finite model of moving guide of hydrostatic guide is established in this paper, then the thermal characteristics of moving guide under different working conditions are analyzed by using ANSYS. Simulation results show that the thermal deformation of moving guide is big when it is doing high-speed variational acceleration motion. Finally the methods of reducing thermal deformation of hydrostatic guide are proposed.This paper also analyzes the thermal characteristics of the ultra-precision diamond lathe under all internal heat source. The lathe's steady-state temperature field is plot and the heat conduction paths from spindle motor are pointed out. Then the thermal characteristics of the whole structure of lathe is evaluated. A water cooling system of spindle system is designed. And the effect of water cooling system is simulated by ANSYS. How the environment temperature change affects the machining accuracy is also analyzed. Finally the influence of the spindle front-end extension to the microstructure surface processing is discussed, and an thermal error compensation scheme is proposed.