Synthesization of thermally induced errors in coordinate measuring machines

Abstract

This work presents the equations for the components of the volumetric error of a Coordinate Measuring Machine (CMM) considering thermal influences. These equations were applied to a moving bridge CMM and combines homogeneous transformations, regression techniques and least squares algorithm. The magnitudes of both the geometric errors and its thermally induced variations were collected by means of a Laser interferometric system, a mechanical square and an electronic level. Simultaneously, temperature values were monitored using T-type Copper-Constantan thermocouples. From the proposed model, components of the volumetric errors were synthesized. Results are discussed and compared to the ones obtained from measurement sets of a ring gauge. It was verified that the model presented an excellent ability to predict volumetric error of the CMM. Errors of about 10µm in magnitude were reduced by at least 75%, while for errors greater than 10µm, the efficiency of the model was 90%