A new method for measuring the rotational accuracy of rolling element bearings

The rotational accuracy of amachine tool spindle has critical influence upon the geometric shape and surface roughness of finished workpiece. The rotational performance of the rolling element bearings is a main factor which affects the spindle accuracy, especially in the ultra-precisionmachining. In this paper, a new method is developed tomeasure the rotational accuracy of rolling element bearings ofmachine tool spindles. Variable andmeasurable axial preload is applied to seat the rolling elements in the bearing races, which is used to simulate the operating conditions. A high-precision (radial error is less than 300 nm) and high-stiffness (radial stiffness is 600 N/μm)hydrostatic reference spindle is adopted to rotate the inner race of the test bearing. To prevent the outer race from rotating, a 2-degrees of freedom flexure hinge mechanism (2-DOF FHM) is designed. Correction factors by using stiffnessanalysis are adopted to eliminate the influences of 2-DOF FHM in the radial direction. Two capacitive displacementsensors with nano-resolution (the highest resolution is 9 nm) are used tomeasure the radial error motion of the rolling element bearing, without separating the profile error as the traditional rotational accuracy metrology of the spindle. Finally, experimentalmeasurements are performed at different spindle speeds (100-4000 rpm) and axial preloads (75-780 N). Synchronous and asynchronous error motion values are evaluated to demonstrate the feasibility and repeatabili...

Source: Review of Scientific Instruments - December 2, 2016 Category: Physics Authors: Ye Chen, Xiangsong Zhao, Weiguo Gao, Gaofeng Hu, Shizhen Zhang and Dawei Zhang Source Type: research