An Experimental and Theoretical Approach for Stiffness of Machine Tool Spindle with Fluid Bearings

Abstract

Machine tool spindle stiffness is a leading technical indicatoraffecting cutting ability. However, the stiffness of the machine tool spindle with fluid bearings has not been studied thoroughly. This paper proposes a new methodology for the spindle stiffness with fluid bearing including definition of the spindle nose stiffness, experimental method and calculation method for this 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 experimental method can be utilized to measure the nose stiffness of spindle with the fluid bearings, meanwhile, the spindle stiffness can be obtained by simultaneously solving the rotor dynamic model and the fluid bearing dynamic model. The fluid bearing spindle stiffness depends strongly on the rotary speed and the external load. We expect an improvement for the experimental device by introducing another load device to apply a perturbation load with an any angle to the external load on the spindle nose.

Study on thermal behavior of an improved motorized spindle with water-lubricated hydrodynamic spiral groove bearings

“…In our previous study [21], the structures of HGJB and SGTB were illustrated, and the equivalent Reynold equations applicable to HGJB and SGTB were derived. To save space and to avoid repetition, the details of modeling for the two bearings are not given herein.…”

“…The cutting force should impact the thermal behavior of the motorized spindle. In this study, a non-contact electromagnetic loading system developed by our laboratory is utilized to apply a load on the front end of spindle, so as to simulate the cutting force, the detail about the loading system was reported in our previous work [21].…”