Study on nonlinear thermal error of the measurement machine

The higher measuring accuracy and velocity of the coordinate measuring machines are required for shorter cycle time in modern manufacturing industry. The high velocity will make the motors and the nuts bring more heat. The measuring accuracy of CMM is limited by the nonlinear temperature distribution components which cause the complicated deformation errors. According to the structural characteristics of a special structure coordinate measuring machine, a thermal expansion body model is established in this paper based on the space transfer matrix. Furthermore, comply with the models of this CMM, the finite element simulation of the thermal expansion errors is carried out. The nonlinear temperature distribution and the deformation which are caused by the temperature gradient of the components can be identified clearly. Laser interferometer was used to measure the thermal deformation errors of CMM under the static condition. The experiment results show that the nonlinear deformation of the base and the column is the significant causes of the measuring error. According to this conclusion, we can provide more effective ways to prevent the nonlinear deformation error. Hence, it is useful to decreasing and restraining the thermal errors and to present a clearer and deeper knowledge of compensation for thermal errors.