Numerical optimization of variable blank holder force trajectory and blank shape for twist springback reduction using sequential approximate optimization

Kitayama, Satoshi; Ishizuki, Ryoto; Yokoyaka, Masaki; Kawamoto, Kiichiro; Natsume, Shinji; Adachi, Kazuaki; Noguchi, Takahiro; Ohtani, Toshio

doi:10.1007/s00170-019-03521-8

Cited by 13 publications

(6 citation statements)

References 33 publications

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“…(10) can also affect the twist springback, the smaller , the smaller twist springback angle. It has also been reported that the twist springback can effectively be reduced by optimizing the initial blank shape, this indicates that improving the flow uniformity of the material is crucial to improve these defects (Kitayama et al, 2019).…”

Section: Analysis Of Split-cut Springbackmentioning

confidence: 96%

On the earing in cup-drawing with non-uniform die clearance: analytical, numerical and experimental approaches

Wang

Dong

Lin

et al. 2021

JAMDSM

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To minimize the earing incurred by the planar anisotropic properties of sheets, a non-uniform die clearance model was proposed for the cup drawing process. The theoretical earing profile height model with non-uniform die clearance was developed based on the combination of radial strain and thickness strain. The Hill 1948 yield criteria was applied to predict geometric earing profile and the anisotropic parameters were calibrated by optimization. It is observed that the predictions of the theoretical model are in agreement with the results of the cup drawing experiments, and the earing profile height is increasingly decreased by the non-uniform die clearance model. Further to this, a numerical model of the deep drawing process was also carried out using the commercial finite element software Abaqus. The results show that the cup drawing with non-uniform die clearance can not only minimize the earing profile height but also reduce the opening springback and twist springback in the split-ring process.

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Section: Analysis Of Split-cut Springbackmentioning

confidence: 96%

On the earing in cup-drawing with non-uniform die clearance: analytical, numerical and experimental approaches

Wang

Dong

Lin

et al. 2021

JAMDSM

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“…Similar to the literature cited in [35], the S-VBHF trajectory was used to represent the design variables for the punch force distribution and the stroke of S-VBHF. Based on the FEA model and experimental results from [33][34][35][36][37][38][39], the total stroke S was divided into three strokes with a constant BHF magnitude in each trajectory. Furthermore, the distribution of segmented BHF of the cylindrical cup was recommended from the result of [33], where the DBRF was constant, and only the BHF changed across the S-VBHF trajectory.…”

Section: Simulation Modelmentioning

confidence: 99%

Numerical multi-objective optimization of segmented and variable blank holder force trajectories in deep drawing based on DNN-GA-MCS strategy

Guo¹,

Jeong²,

Park³

et al. 2023

Preprint

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This research introduces a novel methodology for mitigating defects in sheet metal forming processes. The proposed approach employs a segmented and variable blank holder force (S-VBHF) trajectory, adjusting the blank holder force (BHF) during the forming cycle, enhancing formability, and reducing failure, wrinkling and springback defects. Optimal process parameters, including the S-VBHF, friction coefficient and drawbead restraining force (DBRF), were determined through a systematic methodology integrating deep neural network, genetic algorithm and Monte Carlo simulation (DNN-GA-MCS) techniques. The design constraint, defined as sheet failure during the forming process, was quantitatively evaluated using the forming limit diagram (FLD) to ensure rigorous assessment. The proposed methodology was validated through numerical simulations using a cylindrical cup provided by NUMISHEET 2011 (BM1) as test samples. The simulation results demonstrated a significant improvement in the formed sheet quality, characterized by reductions of 8.33%, 10.81% and 5.88% in failure, wrinkling and springback defects, respectively. These findings underscore the potential of the proposed approach in enhancing the quality of sheet metal forming processes and mitigating defects.

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“…Historically, a constant blank holder force (CBHF) was used in stamping processes, but this method usually results in material flow issues, causing wrinkling at low BHF and failures at high BHF, while increased tension and reduced bending moments might also worsen problems like springback [ 7 , 8 ]. The VBHF technique addresses these issues by allowing for the spatially and temporally variable forces on the blank holder, thus enhancing the control of the material flow [ 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

Numerical Optimization of Variable Blank Holder Force Trajectories in Stamping Process for Multi-Defect Reduction

Guo,

Jeong,

Park

et al. 2024

Materials

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An intelligent optimization technology was proposed to mitigate prevalent multi-defects, particularly failure, wrinkling, and springback in sheet metal forming. This method combined deep neural networks (DNNs), genetic algorithms (GAs), and Monte Carlo simulation (MCS), collectively as DNN-GA-MCS. Our primary aim was to determine intricate process parameters while elucidating the intricate relationship between processing methodologies and material properties. To achieve this goal, variable blank holder force (VBHF) trajectories were implemented into five sub-stroke steps, facilitating adjustments to the blank holder force via numerical simulations with an oil pan model. The Forming Limit Diagram (FLD) predicted by machine learning algorithms based on the Generalized Incremental Stress State Dependent Damage (GISSMO) model provided a robust framework for evaluating sheet failure dynamics during the stamping process. Numerical results confirmed significant improvements in formed quality: compared with the average value of training sets, the improvements of 18.89%, 13.59%, and 14.26% are achieved in failure, wrinkling, and springback; in the purposed two-segmented mode VBHF case application, the average value of three defects is improved by 12.62%, and the total summation of VBHF is reduced by 14.07%. Statistical methodologies grounded in material flow analysis were applied, accompanied by the proposal of distinctive optimization strategies for the die structure aimed at enhancing material flow efficiency. In conclusion, our advanced methodology exhibits considerable potential to improve sheet metal forming processes, highlighting its significant effect on defect reduction.

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Numerical optimization of variable blank holder force trajectory and blank shape for twist springback reduction using sequential approximate optimization

Cited by 13 publications

References 33 publications

On the earing in cup-drawing with non-uniform die clearance: analytical, numerical and experimental approaches

On the earing in cup-drawing with non-uniform die clearance: analytical, numerical and experimental approaches

Numerical multi-objective optimization of segmented and variable blank holder force trajectories in deep drawing based on DNN-GA-MCS strategy

Numerical Optimization of Variable Blank Holder Force Trajectories in Stamping Process for Multi-Defect Reduction

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