以曲線模擠製圓管之研究

STUDIES ON TUBE EXTRUSION USING CURVED DIES

李榮顯(Rong-Shean Lee) ； 邵慧昌(Houy-Chang Shaw)

《鑛冶：中國鑛冶工程學會會刊》 30卷1期 (1986/03) Pp. 49-57

https://doi.org/10.30069/MM.198603_30(1).0004

摘要

金屬擠製時，其流動方式和本身材料之機械性質，模具之幾何形狀及模具與工件之摩擦介面情況存在著極複雜的關係。對於可擠伸性較差的材料，則必須藉著有效的模具輪廓設計，使金屬更均勻地流動，以獲得更高品質的產品。傳統工業界之圓管擠伸模具沿用平模或錐形模，本文提出具有物理意義之合理化模具輪廓曲線設計，應用於圓管擠製，包括有：沿軸向均勻應變增量比維持常數之曲線模，沿軸向平均應變率維持常數之曲線模及流線形（S形）模。本研究針對所提出之各種曲線模具及工業用之平模與錐形模在相同之擠伸比、應變率及潤滑條件下，使用商業用純鋁為模型材料，進行室溫圓管擠製。由擠伸實驗得到使用各種模具輪廓所需之擠伸負荷。又從工件縱剖面之巨觀腐蝕實驗而觀察到金屬在各種模具内之流動方式及塑性變形區。從實驗結果顯示平模擠伸所需之負荷均較各種曲線模為高，利用本文所提出之合理化設計準則可得到比錐形模負荷更低之曲線模具。由巨觀腐蝕實驗而得到不同之模具輪廓對塑性區之影響可用以驗證理論分析所假設速度場之真實性。

並列摘要

In metal extrusion, complex relationship exists between flow pattern and material properties, die geometry and frictional conditions. In order to obtain more homogenous flow, therefore, better quality of the product, an effective die profile design is required, especially for those difficult materials. Instead of flat die and conical die, being used by the conventional tube extrusion industry, three rational concepts of die profile design are presented in this paper, i. e. the curved die with constant ratios of homogeneous strain increments along the pass; the curved die with constant mean strain rate and the sigmoidal die. A series of tube extrusion tests were carried out using the proposed curved dies and conventional flat die and conical dies under the same extrusion ratio, strain rate and frictional condition, with commercially pure aluminium as a model material. The extrusion loads were measured for each test. The longitudinal sections of each specimen were macroetched, then the flow patterns and the boundaries of the plastic deformation zone were observed. The experimental results show that lower extrusion loads are required for the proposed curved dies than those for the conventional dies. The effects of die profiles on the plastic zone have been investigated and validity of the assumed velocity field for the upper bound analysis is discussed.