The Static And Thermal Properties Finite Element Analyses And Experimental Study Of Aerostatic Spindle Used On Dicing

Dicing is the special NC equipment in SIP of semiconductor products, and aerostatic spindle is one of its key components. With the development of high-speed, ultra-precision technology, the stiffness and stability of the aerostatic spindle have a higher demand. As with the compressibility of air, gas film stiffness is smaller, and the inherent heat of spindle may cause deformation of the spindle and affect the precision, so rigidity and thermal characteristics determine the quality of the product processing. Therefore, it is very important to make a research on the stiffness and thermal deformation of the aerostatic spindle to improve its functional performance.Firstly, this article analyzed the principle of aerostatic bearing, established the mathematical model in accordance with the basic equations of fluid dynamics, and proposed the necessity and feasibility of finite element simulation. Those provided the theoretical basis for the subsequent works.Selected the aerostatic spindle of dicing machine as the research object, by studying the structure of one single aerostatic bearing, built its three-dimensional finite element model according to the parameters, got fluid analysis results, and learned the pressure distribution of gas film by observing the cloud. The complete parameter three-dimensional entity model of aerostatic spindle is built up, the simulation analysis is implemented using fluid-solid coupling method, the deformation of the spindle under different loads are obtained,and thus the static stiffness of spindle is calculated.Aiming at the problem that the processing error come from the thermal deformation of aerostatic spindle on dicing saw, the source and transfer of heat of aerostatic spindle were analyzed according to its actual conditions, and the corresponding heat rate and heat transfer coefficient were determined. Simulation model of aerostatic spindle was developed using ANSYS, the temperature field distribution and thermal deformation of aerostatic spindle were simulated by coupling analysis. The results indicate that, axial thermal deformation of spindle due to the rotor end, motor cooling water cools down the rotor through stator indirectly, and it is the best way to reduce thermal deformation of spindle. Then, according to working properties of spindle, measures for reducing thermal deformation were proposed from the standpoint of reducing heat generation and enhancing cooling.Finally, to verify the correctness of theoretical research, this paper established the experimental research system about static and thermal characteristics of aerostatic spindle. The experimental results show that the analysis method took above is feasible within the allowable error range, also provide a strong reference for future theoretical studies.