An improved thermal simulation model for the spindle of CNC machine tool

Abstract

The spindle is an important part of a CNC machine tool, and it is very significant to study how to simulate the deformation of the spindle accurately no matter in theoretical or practical way. Traditionally, the boundary coefficients for simulation have always been defined as some constants with the help of personal experience. This is the main reason for inaccuracy in the thermal model deducing. Referencing the theory on calculation of the heat transfer convection coefficient on a flat plate when air flows along it, this paper proposes a new calculating method on the boundary coefficients. The heat transfer convection coefficients of a rotating spindle are deduced theoretically along with the change over time, and they are the attenuation function against time. Moreover, the dynamical characteristics of the spindle have also been analyzed using the FEM (finite element method). The relationship between temperature of point on spindle and thermal error has been investigated and some satisfying results are achieved at last. Keywords-machine tool; finite element method; boundary coefficient; thermal errorI.