Heat generation modeling of ball bearing based on internal load distribution

In the operation of a machine tool (MT), the frictions in ball bearings entail sudden and violent heating of the balls which dominants its thermal deformation, and subsequently results in degradation of its accuracy and performance. Modeling of the heat generation in a bearing is a quite difficult job because of the constantly changing characteristics. In this paper, an analytical approach was proposed to calculate the heat generation rate of supporting bearing in a ball-screw system of the MT, with consideration of the operating conditions, such as rotation speed and external loads of the machine tool. The influences of operating conditions to internal load distribution, contact angles and heat generation rate of ball bearings were analyzed. The friction torque due to the applied load and the sliding torque within the contact area were discussed in detail. Experiments were carried out in a highspeed ball-screw system to verify the validity of the presented analytical method. The work described in this paper can be seen as a foundation for the accuracy thermal modeling and thermal dynamic analysis of the ball-screw system in the machine tools. (C) 2011 Elsevier Ltd. All rights reserved.