高溫管旋壓縮口分析研究

Abstract

旋壓技術是一種被廣泛運用於製造軸對稱產品之量產方法，本研究將旋壓技術應用於高溫下鋼管瓶口的縮口成型。有限元素分析已成功應用旋壓成型的研究，但目前研究皆在常溫下進行，並未考慮高溫對旋壓縮口的影響。因此，本研究使用有限元素法對於高溫旋壓縮口進行分析研究。 為建構一完整的鋼瓶高溫旋壓縮口之有限元素分析模型，本研究首先進行高溫單軸壓縮試驗，且由於材料在高溫下對於應變率相當敏感，因此在不同應變量 (0.05-0.8)、不同溫度 (873-1273 K)與不同應變率 (0.001-50 s-1) 下進行實驗，以獲得較大範圍的材料性質。接著進行鋼瓶高溫旋壓縮口實驗並以商用軟體Abaqus/Explicit針對相同的實驗參數進行有限元素分析，比較實驗與模擬結果在鋼瓶厚度與外形輪廓上的差異。實驗與模擬的誤差在厚度上為8.94%而在外形輪廓上的誤差為1.4%，有限元素模擬結果與實驗有相當的一致性。 最後運用驗證過的有限元素模型，研究製程參數對於高溫管旋壓縮口的影響。模擬結果顯示，提高輥輪單位時間的進給量會降低旋壓縮口後的鋼瓶真圓度，並且會增加旋壓縮口製程所需的力量。使用曲線路徑進行旋壓縮口的鋼瓶，其厚度分佈比原始設計的均勻。

The tube spinning process is a metal forming process used in the manufacture of axisymmetric products, and has been widely used in various applications. In this study, the neck-spinning process was applied to form the neck part of the tube end at elevated temperatures. Finite element analysis (FEA) has been successfully applied to the tube spinning processes, but no temperature effects have been considered on neck-spinning process. For this reason, the objective of this dissertation is to introduce finite element analysis into investigation of tube neck-spinning process at elevated temperatures. To construct a comprehensive finite element model for tube neck-spinning process at elevated temperatures, this study firstly performed isothermal hot compression tests over a wide range of strain (0.05-0.8), temperatures (873-1273 K), and strain rates (0.001-50 s-1), since the material is sensitive to strain rates at high temperatures. Tube neck-spinning experiments were then performed and the finite element analysis with the same process variables was also conducted by using commercial finite element software, Abaqus/Explicit. Comparisons between experimental and simulation results on thickness distribution and the outer contour of the spun tube were discussed. During the final steps, the average deviations between the simulation and experiment were 8.94% in thickness and 1.4% in outer contour. The simulation results corresponded well with those derived from the experiment. Finally, the verified finite element model for tube neck-spinning process at elevated temperatures was used to investigate the influences of two process parameters: the roller feeding pitch and the roller forming path. The roundness of the spun tube became worse and the roller reaction forces increased as the roller feeding pitch increased. For the roller forming path, the thickness distribution of the spun tube formed by curved paths was determined to be more uniform than that of the spun tube formed by straight paths.