Pressure distribution of gas film and dynamic analysis for gas spindle

The machining precision is greatly influenced by the dynamic characteristics of the gas spindle. Therefore it is necessary to analyze and calculate the pressure distribution of the gas film to deduce the dynamic characteristics. The dimensionless Reynolds lubricating equation was processed with the finite element methods to acquire the pressure distribution of gas film at different poses in the spindle, thereby the counterforce and countertorque in the three axial directions corresponding to the spindle pose was acquired.Then the approximations of the rigidity and the angular rigidity of the gas spindle were discussed. With the rigidity parameter, the dynamic equation of six-freedom was established to obtain the barycenter orbit. Euler equation was introduced to analyze the deflexion of the spindle axes and to discuss the stability of the spindle axes with different geometry parameters. The method to promote the accuracy of machine tools was proposed: to increase the ratio of the radial inertia tensor to the axial inertia tensor of spindles (the pan model spindle with higher diameter-thickness ratio). It provides theoretical basis for the structure design of spindle and calculating method to solve the tool movement orbit.