| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 99 === The steel industry thrives in recent years, and seamless steel tube manufacturing technology is getting mature. The most common method of producing seamless steel tubes is hot extrusion process. This study targets at the hole expansion process which is one of the hot extrusion process of seamless steel tubes. The principle is that the inner diameter of billet is expanded to a large hole. The finite element analysis is applied to simulate hole expansion process in the thesis. In order to obtain material properties, a cylindrical compression test and a ring compression experiments were planned. The stress-strain curve of 304L stainless steel can be obtained by the cylindrical compression, and the friction coefficient of the interface between the mold and material can be obtained by the ring compression. The end effect occurs in the cylindrical compression, and the stress-strain curves need to be calibrated according to the literature, and the result after calibration is shown. Importing the experimental data into finite element analysis allows more accurate model, and the reaming force value of simulation is verified with the actual data. In the simulation results, the relationship of initial billet temperature and reaming speed between reaming forces is investigated and discussed. The results showed the initial billet temperature has more significant effect to the reaming force. By fixing the length and the bottom diameter of reaming cone, the effects of changing the taper of the reaming cone are then studied. According to the simulation results in the changing of the reaming cone shape, the key parameter for the reaming force is the taper of the reaming cone.
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