An experimental and theoretical approach for stiffness of machine tool spindle with fluid bearings

Spindle nose stiffness is a leading technical indicator of machine tool spindle. However, the stiffness of machine tool spindle supported by fluid bearings has not been studied thoroughly, by far; there is not an ideal approach to obtain the spindle nose stiffness due to the nonlinear fluid bearings. This paper proposes a new methodology for the spindle nose stiffness including definition of the spindle nose stiffness with the fluid bearings, experimental and theoretical approach to obtain the spindle nose stiffness. A motorized spindle with hydrodynamic water-lubricated spiral groove bearings developed in our laboratory is selected as an object; a theoretical and experimental investigation on the spindle nose stiffness is conducted. The result shows that the proposed methodology is applicable for obtaining the spindle nose stiffness with the fluid bearings; the experimental device has the advantages of simple structure, low cost, and convenient operation. Meanwhile, the spindle nose stiffness can be calculated by simultaneously solving the dynamic model of rotor-bearing system. We expect an improvement for the experimental device by introducing another load device to apply a perturbed load with an any angle to the external load on the spindle nose.

Automated summary

This paper focuses on the stiffness of machine tool spindle supported by fluid bearings and proposes a new methodology to obtain the spindle nose stiffness. The proposed methodology is validated through experimental and theoretical investigation on a motorized spindle with hydrodynamic water-lubricated spiral groove bearings. The results show that the methodology is applicable and the experimental device has advantages of simplicity, low cost, and convenience. Additionally, improvement is expected by introducing another load device to apply perturbed load to the spindle nose.