A strategy of investigation on the thermal behaviour of motorised spindles under high-speed machining. (27th September 2006) - Prabhu Raja, V.
Motorised spindles used for high-speed machining are notorious for their sudden catastrophic failures at high speeds mainly due to bearing thermal problems. Loss of machining accuracy is another major problem due to thermal deformation of the spindle, which transmits motion to the cutting tool or to the workpiece. In this paper, a mathematical model to estimate the frictional losses in high-speed angular contact ball bearings and a heat dissipation model are developed. The steady state temperature distribution and thermal deformation of spindle are determined by finite element analysis considering both bearing and motor heat generation. The simulated temperature results are compared with experimental values reported elsewhere in the literature for validation. The influence of external cooling on the thermal behaviour of spindle bearings and spindle nose deformation is then investigated. An empirical equation is developed to accurately predict the bearing temperature rise.