Simulation of Air Gap Thickness Variations on Air Spindle Vibrations in Ultra Precision Machine Tools

Air spindles are one of the main elements of precise machine tools. Vibration of these spindles is one of the vital issues necessary for investigation. Among parameters which influence air spindle vibrations are rotational speed, compression air method, input nozzle diameter, air gap pressure. In this study using ANSYS, the effects of air gap thickness on air spindle vibrations have been investigated. In this simulation the air gap is modelled by numbers of linear springs. Then the effect of air gap thickness on air spindle vibrations has been investigated. Rotor externally rotates around stator. Simulation results indicate that for static and transient analysis the values of radial displacements of rotor reduce by decreasing spring length (i.e. rotor and stator gap), and its minimum value are equal to 3.634 ?m and 15.6 nm, respectively. Because of constant spring stiffness, in modal and harmonic analysis, results for different spring length have no variation and are equal to 1.053 mm and 23.7 nm, respectively.