Determining a prediction equation for thermal deformation of a CNC lathe using the experimental design

Abstract

This study presents a method suppressing thermal deformation of a computer numerical control (CNC) lathe. Although the thermal deformation of machine tools often reduces their accuracy, it cannot necessarily be prevented by ensuring their rigidities, etc. Therefore, we have been trying to compensate for the thermal deformation by predicting their variations and adjusting the position of the tool according to predicted values. The previously proposed method determined a prediction equation of the thermal deformation in the CNC lathe by measuring the temperature variations at a few specific points of the body. However, the equation needs to exchange the coefficients of the prediction equation depending on whether cutting fluid is used or not. Thus, this study tries to propose a method to determine the coefficients that can be used for machining with and without cutting fluid. Furthermore, the determined coefficients need to be ensured for a wide range of machining conditions such as temperature variations. In order to obtain such coefficients with a few experiments, the present study determines actual cutting conditions to obtain the coefficients with the experimental design and confirms the prediction equations with the determined coefficients to be applicable under wide machining conditions involving temperatures and cutting fluid.

Keywords

• machine tool
• thermal deformation
• compensation
• expermntal design
• temperature measurement