發(fā)布時間：2018-04-02 00:17

  本文選題：拉延筋　切入點：成形質(zhì)量　出處：《合肥工業(yè)大學(xué)》2017年碩士論文

【摘要】：在汽車覆蓋件成形過程中,會出現(xiàn)起皺、拉裂、回彈等現(xiàn)象,工程師往往通過設(shè)置拉延筋來改善板料的成形缺陷。傳統(tǒng)拉延筋的形式較單一,使得板料成形質(zhì)量不夠理想。針對以上實際問題,該文以板料塑性成形理論為基礎(chǔ),通過設(shè)計五種不同組合形式拉延筋,運用有限元數(shù)值模擬方法,對HSLA350與AL6061兩種材料進行U形件拉延有限元分析,分別得出兩種材料六種模型的成形極限圖及減薄率。結(jié)果表明:外推40mm拉延筋確實能夠改變板料的應(yīng)力分布,改善板料的成形質(zhì)量。在六種模型中,外推拉延筋模型中流過拉延筋后板料主應(yīng)力最小,減薄率最小。在回彈數(shù)值模擬中,預(yù)測了所有U型件模型的回彈位移及側(cè)壁角度。結(jié)果表明:拉延筋能有效抑制側(cè)壁回彈,其中外推拉延筋的回彈位移與側(cè)壁角度最小。從理論上揭示U型件側(cè)壁角度與板料應(yīng)力梯度之間的關(guān)系,得出外推40mm拉延筋能夠改變材料應(yīng)力梯度,且梯度值最小。證明其強化后的材料不再流入模腔內(nèi)部,達到改善U形件側(cè)壁翹曲的目的。本文自主設(shè)計U型件沖壓實驗?zāi)＞?完成兩種材料六種模型的沖壓實驗。實驗結(jié)果表明,外推40mm拉延筋模型中的板料成形效果最好,無起皺、開裂等現(xiàn)象。在側(cè)壁減薄率結(jié)果中,HSLA350材料外推40mm拉延筋的板料減薄率最小;AL6061材料所有模型減薄率較為接近。在側(cè)壁翹曲程度結(jié)果中,兩種材料中外推40mm拉延筋模型中板料的側(cè)壁角度小于其他組別,驗證了模擬仿真結(jié)果的準確性。
[Abstract]:In the forming process of automobile panel, wrinkle, crack, springback and so on will appear. Engineers often use drawing bars to improve the forming defects of sheet metal.The traditional form of drawing bar is single, which makes the forming quality of sheet metal not ideal.In view of the above practical problems, based on the theory of sheet metal plastic forming, this paper designs five kinds of drawing bars with different combination forms, and applies the finite element numerical simulation method to the finite element analysis of HSLA350 and AL6061 for U-shaped drawing.The forming limit diagram and thinning rate of six models of two kinds of materials were obtained respectively.The results show that extrapolated 40mm drawbars can change the stress distribution of sheet metal and improve the forming quality of sheet metal.Among the six models, the main stress and the thinning rate of the sheet metal after flowing through the drawing bars are the minimum in the extrapolation drawing bar model.In the numerical simulation of springback, the springback displacement and lateral wall angle of all U-shaped models are predicted.The results show that the springback of the side wall can be effectively inhibited by the drawing bar, and the springback displacement and the lateral wall angle of the extrapolation drawbar are the least.The relationship between the lateral wall angle of U-shaped workpiece and the stress gradient of sheet metal is revealed theoretically. It is concluded that extrapolated 40mm drawbars can change the stress gradient of the material and the gradient value is the minimum.It is proved that the reinforced material will no longer flow into the cavity, which can improve the warpage of the U-shaped side wall.In this paper, U-shaped stamping test die is designed, and six models of two kinds of materials are completed.The experimental results show that the sheet metal forming effect is the best in the extrapolated 40mm drawing bar model without wrinkling and cracking.In the results of side wall thinning rate, the sheet metal thinning rate of HSLA350 material extrapolated with 40mm drawing bar is the lowest and the thinning rate of all models of AL6061 material is close to each other.In the results of side wall warping degree, the lateral wall angle of sheet metal in 40mm drawing bar model is smaller than that in other groups, which verifies the accuracy of simulation results.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG386

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本文編號：1697943