金屬板材方杯深引伸成形極限之動顯函有限元素分析

The Explicit Dynamic Finite Element Analysis of Forming Limit in the Square-Cup Deep Drawing Process of Sheet Metal

鄧維明(Wei-Ming Teng)

指導教授 ： 李經倫

淡江大學/工學院/機械與機電工程學系碩士班/碩士(2006年)

https://doi.org/10.6846/TKU.2006.00949

摘要

本文係利用動顯函有限元素分析程式，結合Hill的異向性降伏準則，來進行金屬板材方杯引伸成形製程之成形極限分析，並探討方杯引伸成形之沖頭負荷與衝程關係、應變分佈、變形歷程、工件厚度變化及成形極限等，並設計一組方形模具加以實驗，以驗證此有限元素分析程式的可信度。
本文藉由設計不同參數之方形模具進行方杯引伸成形分析，探討模具參數對工件成形性之影響，經由比較數值分析之結果得知，方杯引伸成形後，其最小厚度值集中於工件與沖頭角隅接觸的部位，最大沖頭負荷隨沖模及沖頭平行邊寬入模圓弧角之增加而減少。於相同初始料片直徑設定下，較大的沖模及沖頭平行邊寬入模圓弧角引伸成形後有較大的工件最小厚度值，且由方形沖頭平行邊寬與料片之最大直徑所定義之極限引伸比(LDR)得知，當沖模平行邊寬入模圓弧角由R4.0mm增加到R12.0mm，則LDR會由2.514提昇到2.632；當沖頭平行邊寬入模圓弧角由R4.0mm增加到R12.0mm時，則LDR會由2.548提昇到2.608；在五種不同模具間隙設定，其LDR之模具間隙大小依序為C=1.25t、C=2.19t、C=1.56t、C=1.1t、C=1.08t。數值分析之結果皆可合理的模擬實驗結果，故本動顯函有限元素分析程式可合理的預測方杯引伸成形極限。

關鍵字

動顯函有限元素 ； 方杯引伸 ； 極限引伸比

並列摘要

The objective of this study was to analyze the forming limit of the square cup drawing process by using the dynamic-explicit finite element program based on the Hill’s anisotropic yield criterion. Simulation results included the relationship between punch load and punch stroke, the distribution of the strain, the deformation history, the variation of the workpiece thickness, and the forming limit. A set of tools was designed for experiment to verify the reliability of the program.
The present study discussed the square cup drawing process by changing the geometric size of tools. According to the simulation and the experiments results, the minimum thickness was concentrated on the contact regions between workpiece and punch corners. The maximum punch load decreased as the die arc radius and punch radius became larger. With the same of initial blank diameter, larger die arc radius and punch radius would get larger minimum thickness value after deep drawing. According the definition of limit drawing ratio (LDR), when the die arc radius increased from R4.0mm to R12.0mm, LDR would increase from 2.514 to 2.632. When the punch radius increased from R4.0mm to R12.0mm, LDR would increase from 2.548 to 2.608. In the five sets of different tool clearance, the sequence of LDR was C=1.25t, C=2.19t, C=1.56t, C=1.1t and C=1.08t. And the simulation result also showed good agreement with the experiments and therefore the dynamic-explicit finite element program can estimate the forming limit of the square cup drawing process reasonably.

並列關鍵字

Dynamic-explicit finite element ； Square cup drawing ； Limit drawing ration ； Forming limit

參考文獻

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