本文選題：板料成形　切入點：回彈　出處：《湖南大學》2016年碩士論文

【摘要】：回彈是沖壓成形工藝的主要缺陷之一,也是影響沖壓件尺寸精度的主要因素。隨著高強度鋼板等新沖壓板材的廣泛應用以及沖壓件形狀的日益復雜,回彈問題變得越來越突出。傳統(tǒng)的解決方法主要基于經(jīng)驗積累,花費了大量的時間和人力,隨著板料成形數(shù)值模擬技術的出現(xiàn)和發(fā)展,利用有限元數(shù)值模擬技術解決回彈問題已經(jīng)成為研究的主流。因此本文基于有限元數(shù)值模擬技術對回彈問題進行了研究,本文主要工作如下:1.針對差厚拼焊板相對單一板料的不同之處,分析成形數(shù)值模擬對回彈預測的影響,并提出差厚拼焊板的有限元精確建模方法。該方法在差厚拼焊板的板料建模過程中準確設置不同厚度板料的中性層位置,然后對模具網(wǎng)格設置模具階梯,并依靠焊縫線的位置和沖壓成形過程中焊縫線漂移距離確定模具階梯曲線的位置,從而得到精確的有限元仿真模型用于差厚拼焊板的沖壓成形數(shù)值模擬計算。通過一算例證明精確建模方法能夠提高成形及回彈的預測精度,可以用于差厚拼焊板的有限元數(shù)值模擬計算。2.對汽車覆蓋件的迭代回彈補償過程進行了研究,考慮到回彈補償每次迭代都需要利用上一次板料的補償結果構建新的模具網(wǎng)格,本文提出一種新的模具網(wǎng)格重構方法用于回彈補償?shù)牡嬎�。該方法基于有限元的沖壓數(shù)值模擬方法,利用板料網(wǎng)格與模具網(wǎng)格的對應關系將板料網(wǎng)格的補償量賦予模具網(wǎng)格,實現(xiàn)模具網(wǎng)格的補償。具體方法是:通過數(shù)值模擬軟件模擬回彈工序得到零件的回彈計算結果,利用節(jié)點反向映射的方法補償零件的回彈誤差,將修邊工序修剪掉的工藝補充網(wǎng)格做出調整,然后分別拼接到修邊后和補償后的零件網(wǎng)格上得到相應的拼接網(wǎng)格,將模具網(wǎng)格節(jié)點映射到成形的拼接網(wǎng)格,再在補償?shù)钠唇泳W(wǎng)格上生成補償?shù)挠成潼c,反向映射補償?shù)挠成潼c即可得到補償?shù)哪＞呔W(wǎng)格節(jié)點,從而得到補償模具網(wǎng)格。3.以某轎車前艙內橫梁模型為例,對其進行沖壓數(shù)值模擬仿真,利用節(jié)點反向映射的補償方法迭代補償回彈,并利用本文提出的回彈迭代計算中完整工具網(wǎng)格構建的方法構建工具網(wǎng)格,分析驗證該方法的可行性。
[Abstract]:Springback is one of the main defects in stamping process, and it is also the main factor that affects the dimensional accuracy of stamping parts. With the wide application of new stamping plates such as high strength steel plates and the increasing complexity of stamping parts' shape, The springback problem becomes more and more prominent. The traditional solution is mainly based on the accumulation of experience, and it takes a lot of time and manpower. With the emergence and development of numerical simulation technology of sheet metal forming, Using finite element numerical simulation technology to solve springback problem has become the mainstream of research. Therefore, based on finite element numerical simulation technology, the springback problem is studied in this paper. The main work of this paper is as follows: 1. In view of the difference between differential thickness TWW plate and single sheet metal, the effect of numerical simulation on springback prediction is analyzed. The finite element precise modeling method of differential thickness TWW plate is proposed, which sets the neutral layer position of different thickness TWW plate accurately in the course of the plate modeling process, and then sets the mould ladder to the die mesh. The position of step curve of die is determined by the position of weld line and the drift distance of weld line during stamping forming. Thus the accurate finite element simulation model is obtained for the numerical simulation of the stamping forming of the differential thickness TWW plate. An example is given to prove that the accurate modeling method can improve the prediction accuracy of the forming and springback. This paper studies the iterative springback compensation process of automobile panels, considering that each iteration of springback compensation needs to use the compensation results of the last sheet metal to construct a new die mesh. In this paper, a new mesh reconstruction method is proposed for the iterative calculation of springback compensation, which is based on the finite element method of stamping numerical simulation. The compensation amount of sheet metal mesh is given to die mesh by using the corresponding relation between sheet metal mesh and die mesh, and the compensation of die mesh is realized. The concrete method is: the springback calculation result of parts is obtained by simulating springback process by numerical simulation software. Using the method of node reverse mapping to compensate the springback error of the parts, the trimming process trimmed process supplementary mesh is adjusted, and then spliced to the trimmed and compensated parts mesh respectively to obtain the corresponding splicing mesh. The die mesh node is mapped to the formed splicing mesh, and then the compensated mapping point is generated on the compensated splicing grid, and the compensated die mesh node can be obtained by reverse mapping the compensated mapping point. Thus, the compensation die mesh. 3. Taking the model of the cross beam in the front cabin of a car as an example, the stamping numerical simulation is carried out, and the compensation method of node reverse mapping is used to compensate the springback iteratively. The method proposed in this paper is used to construct the tool grid, and the feasibility of the method is analyzed.
【學位授予單位】：湖南大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：U466;TG386

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