| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 104 === This study investigated the thermal displacement characteristics of a domestic three-axis vertical machining center. First, the machining center was operated at different rotational speeds to explore the temperature variation and the thermal deformation of the structure. Based on the experimental measurements, a multi-physics simulation model was constructed, modified and validated. This model was then used to predict the thermal deformation, as well as to evaluate the critical positions of temperature monitoring and control. Moreover, a cooling fan was used to enhance the convective heat transfer of the spindle head. This study further proposed an adaptive thermal balance technology to manage the temperature distribution of the spindle head structure, mitigating its thermal displacement, and thus improving the machining accuracy. Previous studies to the same three-axis vertical machining center that were carried out in our group clearly pointed out that the temperature distribution of the ribs on the spindle head have significant influence to the thermal displacement, especially thermal bending. The optimal locations on the ribs for heaters to adjust the temperature distribution were determined by using optimization software. Experiments were conducted to verify the effects of the heaters at a variety of spindle speed. In addition, a correlation analysis to the temperature and thermal displacement of the cutting point was carried out. With the proposed adaptive thermal balance technology it has been shown that the thermal error of the machine tool can be effectively reduced without changing the structural design of the machine.
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