Reliability optimization design for stochastic static deformation of computer numerical control lathe spindle

The number and the mean price of lathes manufactured in China are, respectively, large and low. However, the reliability of these lathes is comparatively lower to lathes manufactured in some countries. To overcome this major drawback, the reliability optimization design for the failure due to the overlarge static deformation of the computer numerical control lathe spindle is presented here. First, the static deformation of the spindle front end is formulated. This deformation results from the pre-tightening force acting on the front cylindrical roller bearing and the cutting force applied to the spindle front end. In the next step, the corresponding reliability is modeled and estimated. An expression for sensitivity calculation is determined. Subsequently, the reliability optimization method is proposed and is illustrated using a numerical example. The results show that the reliability corresponding to the stochastic static deformation of the computer numerical control lathe spindle was improved, and the reliability robustness increased significantly using the proposed method.