Method for measuring thermal distortion in large machine tools by means of laser multilateration

Abstract

A new methodology to measure thermal distortion in large machine tools is proposed in this paper. The advantage of this method is that a single tracking interferometer can be used to measure thermal distortion of machines with large work volumes while maintaining low enough measurement cadence and uncertainty. A multilateration scheme is conducted using a single laser tracking device positioned on top of the machine table which is automated, and for each target point, all laser stations are reached prior to moving to the next target point; then, the whole measurement cycle is repeated during the test. For measuring angular thermal distortion, precision electronic levels are located in machine ram and column top; also, temperatures are registered in key points of the machine. Experimental measurements on a large column-type milling machine are done, and the effectiveness of the proposed methodology is verified.