| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 98 === The ballscrew has good performance namely high efficiency and speed, low friction and wear, precision positioning and so on. It has widely been applied to accuracy machines that need high precision. Nevertheless, the temperature increment during operation will affect the precision of ballscrew. Therefore, it is given pre-tension as compensation while ballscrew assembly. This study is aimed to investigate how the ballscrew pre-tension will affect by the pre-tension force changes and temperature increment.
In this study, it mainly investigate into component of a double-nut ballscrew, then the numerical analysis of pre-tension force and temperature increment on mechanics of materials is implemented. The next stage is to design the experiments. The three main experimental parameters are pre-tension, rpm and duration of running. Through the measurement by Washer-Type Load Cell, Strain Indicator and Recorder, and Infrared Thermometer to observe the changes of axial pre-tension force and temperature increment of screw under the parameters setting. The experimental results reveal that pre-tension force decrease and temperature increase progressively by increase with time and rpm. According to the experimental results, the average error of pre-tension force between measurement and theoretical value is 16%~24%. While the rpm increase, the average error will decrease. By the curve fitting from this study, it is summarized an empirical formula for ballscrew pre-tension changes and temperature increment, then arrange the relationship among pre-tension changes, temperature increment and rpm. It could be a reference to adjust the pre-tension for ballscrew assembly.
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