利用有限元素軟體進行漸進成形的回彈現象分析

Abstract

漸進成形加工乃利用成形工具沿著設定的路徑移動，逐步造成板材變形以製作出所需要的工件，無需製作和更換昂貴的模具，因此能有效地進行少量製造，從而實現產品的客製化。儘管漸進成形技術具有高度的自由度，其精度控制與預測仍未得到充分解決。本研究運用有限元素軟體Abaqus對AA1050-O板材單點、雙點漸進成形進行回彈分析，目的是研究兩種加工方法的異同。本研究主要分析單點、雙點漸進成形的回彈現象，量化回彈並討論漸進成形中回彈的成因。 從模擬的結果得知，雙點漸進成形和單點漸進成形相比，雙點漸進成形整體的回彈量較大，不過可以透過路徑補償提高加工精度，也因此使用雙點漸進成形可以更有效地控制變形，從而達更好的輪廓和精度。由於單點漸進成形與雙點漸進成形的加工路徑不同，造成單點漸進成形的局部回彈是向杯內回彈、雙點漸進成形則會是向杯外回彈。同時，因為包辛格效應會導致材料軟化，在同樣的加工條件與加工路徑下，其模擬結果的應變會比沒有考慮包辛格效應的模型來得大。而單點漸進成形和雙點漸進成形不管有沒有考慮包辛格效應的模型產生的輪廓與實驗的輪廓都差異不大，代表方杯的形狀在漸進成形中可忽略包辛格效應的影響。在同樣的加工路徑下，因AA6061-T6的降伏強度較高，模擬結果的殘留應力會比AA1050-O來得大，且AA6061-T6在側壁回彈量的部分會比AA1050-O多。未來可建立不同材質板材的模型(如高強度鋼)進行CAE分析，或使用全模具來代替部分模具，以提升漸進成形在加工產業的應用。

Incremental forming utilizes forming tools that move along a predetermined path, gradually deforming the sheet metal to create the desired workpiece. This process eliminates the need to create and replace expensive molds, making it efficient for small-scale manufacturing and enabling product customization. Despite the high degree of freedom offered by incremental forming technology, accuracy control and prediction remain unresolved issues. This study uses the finite element software Abaqus to analyze the springback in single-point and two-point incremental forming of AA1050-O sheets, aiming to investigate the differences between the two methods. The research mainly analyzes the springback phenomenon in single-point and double-point incremental forming, quantifies the springback, and discusses its causes in incremental forming. Simulation results indicate that two-point incremental forming exhibits greater overall springback compared to single-point incremental forming. However, precision can be improved through path compensation, making two-point incremental forming more effective in controlling deformation, thus achieving better contours and accuracy. Due to the different processing paths of single-point and two-point incremental forming, single-point incremental forming results in inward springback towards the cup, while two-point incremental forming results in outward springback away from the cup. Additionally, since the Bauschinger effect causes material softening, the strain in the simulation results under the same processing conditions and path is greater in models considering the Bauschinger effect compared to those that do not. The contours produced by single-point and two-point incremental forming models that do not consider the Bauschinger effect are closer to the experimental contours, indicating that the shape of the square cup in incremental forming can disregard the influence of the Bauschinger effect. Under the same processing path, the residual stress in the simulation results for AA6061-T6, which has higher yield strength, is greater than that for AA1050-O. In the future, models for sheets of different materials (such as high-strength steel) can be established for CAE analysis, or full molds can be used instead of partial molds to enhance the application of incremental forming in the manufacturing industry.