A New Method for Determining the Thermal Contact Resistance at Machine Tool Joints

Abstract

Summary A method of measurement of thermal contact resistance in condition of contact pressure exhibiting a distribution, is presented. This is the case which occurs at the machine tool joints, as the theory of their nonlinear thermoelastic behaviour developed by the authors, indicates. The new method is based on the concept of generating various distributions of contact pressure, which makes use of the finding that the relative dimensions of contacting specimens, expressing their relative stiffness, affect the contact pressure distribution. Thus, it is a basic departure from existing methods, in which thermal contact resistance is measured for a single, average value of contact pressure, not representing realistically conditions of neat transfer across the machine tool joints. The new concept has been verified experimentally by applying the photoelasticity technique and through the finite element analysis. Two dimensional heat transfer and plane strain conditions has been assured in the experiment, which provides the data of thermal contact resistance distribution correlated to the distribution of the contact pressure. The test rig constructed to satisfy the requirements of the new method is described along with the measurement techniques and data processing. Preliminary results indicate satisfactory performance of the experimental setup. Data which will be obtained using the new method, will be applied to calculate the thermal deformation of the machine tool structure with the effect of joints accounted for, following the methodology developed by the authors.