| Summary: | 碩士 === 國立勤益科技大學 === 冷凍空調系 === 105 === The thermal error is the most important error source of ultraprecision machine tools, and the thermal deformation resulted from temperature rise during cutting processing sometimes degrades the machining precision and quality. The thermal deformation results in 40% to 70% of the errors in the machining of machine tools. As it is difficult to avoid heat production in the operation of machine tools or in the cutting processing, how to predict the temperature change of machine tool to design effective thermal management measures is an important task for developing ultraprecision machine tools.
In this study, the thermal deformation is analyzed for the main cast iron and carbon steel materials of machine tools, and the embedded cooling runner is used for heat exchange cooling of the heat generated in the dynamic feeding process of machine tool, so as to suppress the thermal error. The optimum cooling runner and cooling conditions are simulated by using finite volume method, combined with cooling machine to suppress the heat for the linear motor feed system, so as to increase the positioning accuracy of feed system. According to the simulation results, the lower the cooling oil temperature in the embedded cooling runner is, the more heating value of slide rail is taken away, and the average temperature of slide rail is reduced, so that the thermal deformation decreases. The experiment shows based on the thermal suppression of embedded cooling runner, when the hydrostatic slide rail cooling is turned off for dynamic feed, the positioning accuracy of feed system is improved by about 25.5%. When the hydrostatic slide rail cooling is turned on for dynamic feed, the positioning accuracy is improved by at most 36.4%. However, the optimum positioning accuracy does not occur at the minimum cooling oil temperature. This phenomenon means higher cooling capacity does not lead to better positioning accuracy. In terms of simulation, the lower the temperature is, the less the thermal deformation is, but if the cooling capacity approaches to the heat flux of machine in actual machining, there will be steadier performance in the positioning accuracy of machine tool.
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