Design And Characteristics Research Of Gas Lubricated Bearing High-speed Motorized Spindle

Aerostatic bearing electric spindle has a huge application prospect in modern high precision-high speed CNC machining center due to its high precision processing, high rotation speed, high efficiency and pollution-free.Oil bearing and antifriction bearing of electric spindle are still the main support method in milling process. This support form has the advantage of great bearing capacity and high stiffness, but the rotation speed is approximately10000r/min, and it still can not meet the demand of high precision, high rotation, thus the design and research on gas bearing high speed electric spindle is become significant.The purpose of this project is to design an electric spindle which can be used in vertical high speed milling process, the support form is aerostatic bearing, Dn value of electric spindle has to be more than two million, mainly used in ultra-precision milling. An in-depth research on general structure design scheme, stress distribution of electric spindle analysis, the structure design of main parts, as well as the design and characteristics of orifice restriction aerostatic bearings is be studied in order to reach desired design goal. The research contents concern:Firstly, based on the design goal and demands, preliminary determined overall design scheme of electric spindle, then based on the the overall structure obtain key parameters of later structure design from overall force analysis of end-plane milling tool in vertical milling processing.Then, upon overall structure analysis and force analysis, firstly, the decision of induction motor is determined, the required fit interference value, which is the torque output needed during the interference fit process of internal motor and electric spindle, is calculated according to force analysis. Secondly, the cooling systems of electric spindle is designed, the designed single-screw cooling systems are able to meet the selected interference motor’s normal operating demands. Thirdly, according to the structure of facing cutter designed the shaft ends of electric spindle to meet the facing cutter’s assembly requirements.Finally, relative structure of required orifices throttling aerostatic bearing is designed by adopting empirical formula method.To test and verify the reliability of designed aerostatic bearing, the analysis of aerostatic bearing is simulated based on FLUENT. First establish its3D model, then optimize its solid mesh dividing, at last, bearing capacity and the characteristic of stiffness of both transverse aerostatic bearing and thrust aerostatic bearing are studied respectively.The research results above provide a practical design approach for electric spindle’s milling progress, the support form of which is aerostatic bearing, and be able to design, and further improve this kind of electric spindle and aerostatic bearing.