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The reduction of the thermal errors of a CNC machining Center isthe major work in this research. However, the purpose of producingthe accuracy products and increase the machine value are conducted at last. The evidence shows 40 to 70% of total error are caused by machine''''s thermal drift. It is important to develop a method to fill the thermal drift, which associated with a changing temperature distribution within the structural loop due to internal and external sources. The statistical regression analysis is used to establish the thermal drift model. With the feedback control algorithms, the mathematical model can be used as a compensation matter on-line to improve the thermal drift problem. In this research, an IC type with intelligence thermal sensor, AD590, is used. Thermal sensors with the ADVANTECH 812 A/D converter and the personal computer constructed as a data acquisition system. The displacements caused by the thermal drift are measured by using LTO2S displacement gauge, which is a product of RENISHAW for lathe. The mathematical models, which are function of temperature varying and thermal displacement, are established based on the multi-variable regression and nonlinear regression statistical methods. The advancing compensation methods that include hardware and software methods are conducted in this research. With the experiments, the results showed the research design with software compensation method can control the thermal drifts within 5mm.
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