| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 103 === In this study the thermal deformation of a 3-axis machining center was analyzed experimentally and numerically. In the experiments, temperature variations of multiple (~40) points on the spindle head structure and the displacement of the cutting point with respect to time were measured. In the numerical analysis, a finite element method software (ANSYS) was utilized to simulate the transient thermal-fluidic-thermal elastic behavior of the spindle head structure. The numerical results are in reasonable agreement with the experimental results. Characteristics of the thermal behavior of the spindle head were discussed based on comparing the experimental and numerical results. It was found that the displacement of the cutting point was significantly titling. The key component that greatly affects this nonlinear thermal deformation (tilting) was revealed to be the ribs on the spindle head. This nonlinear thermal deformation cannot be reduced by using conventional thermal error compensation techniques. Therefore, to address this issue, a novel adaptive thermal balance (ATB) technology was proposed and tested in this study. Small rubber heaters and thermoelectric cooling (TEC) units were used to adjust the temperature distributions on the spindle head. Design parameters of the heaters and TECs were determined from optimization analyses based on the constructed simulation model aforementioned. Experimental results confirmed that by applying the ATB technique, a 77% reduction on the nonlinear thermal deformation can be achieved. In conclusion, the current study provides a comprehensive analysis of the thermal characteristics of the modeled machine tool. Furthermore, the developed thermal balance technology is proven to be able to adaptively and smartly adjust the temperature distribution, which in turn significantly improves the machining accuracy.
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