The influence of thermophysical parameters on the prediction accuracy of the spindle thermal error model

The model based on the velocity and acceleration of temperature variation (MBOTV) was established for spindle thermal growth error. However, the thermophysical parameters of MBOTV, such as the thermal expansion coefficient related to the velocity of temperature variation, Hv, the thermal expansion coefficient related to the acceleration of temperature variation, Ha, and the thermal inertia coefficient of the spindle, τ, may change during actual working. In order to analyze the influence of thermophysical parameters on the prediction accuracy of MBOTV, it is necessary to calculate the reliability of MBOTV. Actually, it is difficult to obtain the function of MBOTV. Although the improved response surface method can be used to calculate the reliability of the model with implicit function, the accuracy is not enough obviously when the implicit function is replaced by linear polynomials. Therefore, an improved response surface method based on quadratic polynomial approximation was proposed in this paper to calculate the reliability of MBOTV. In this method, the linear polynomial was replaced by a quadratic polynomial without cross product terms to replace the implicit function, which can improve the accuracy of reliability calculation. The predicted residual errors of MBOTV with single-parameter fluctuation and multi-parameter fluctuation were given in this paper. Studies reveal that MBOTV has strong robustness when the thermophysical parameters change.