利用凹槽設計於圓柱鍛粗試驗之可行性探討

Feasibility Study on the Application of Notch Design on Cold Upsetting Test

李榮顯(Rong-Shean Lee) ； 陳彥儒(Yen-Ju Chen) ； 王水鐸(Shui-To Wang)

《鍛造》 13卷4期 (2004/11) Pp. 29-34

https://doi.org/10.29791/Forging.200411.0001

摘要

對於金屬材料而言，獲得其成形極限與觀測其破壞現象對於模具設計與製程設計相當重要。若利用圓柱鍛粗試驗欲得到其成形極限，必須透過增量實驗以觀察其破壞的情況。而針對目前精微成形產業常用之高延展性之金屬材料，由於其延展性優良，導致成形極限之建立與破壞發生之觀測更加困難。因此吾人希望針對高延展性材料的成形極限獲得尋找一可行的定義方法。利用具應力集中效果之凹槽設計，透過此種幾何缺陷加速試件之破壞，以利成形極限之獲得。透進文獻可以發現，凹槽設計有助於加速試件破壞的發生，而由模擬結果可證實，不同凹槽之設計，則有不同程度之應力集中效果。透過有限元素法，可獲得凹槽尖端與自由表面之應力、應變狀態，并以破壞應變能量之累積判斷材料在何時、何處發生破壞。本文利用套裝軟體DEFORM-3D，模擬數種具應用集中效應之圓柱鍛粗試驗，并以破壞準則進行分析。最後對於高延展性材料的成形極限試驗提出凹槽設計之方向。

關鍵字

圓柱鍛粗試驗、凹槽設計、成形極限

並列摘要

An important concern in die design and process design is to find the workability and the forming limit for the material. For the materials that have good ductility, it is hard to obtain the forming limit using simple upsetting test. In this paper, a new upsetting test method with notch on the surface was proposed to obtain the forming limit. A finite element analysis package DEFORM-3D was used to simulate the notched upsetting tests. Ductile fracture criterion was then applied to predict the initiation of surface fracture on the notch tip and the free surface. In the end, a design concept of notched specimen was proposed for the forming limit test of high ductility materials.

並列關鍵字

upsetting test ； notch design ； forming limit