A comprehensive electromagnetic forming approach for large sheet metal forming

Lai, Zhipeng; Cao, Quanliang; Han, Xiaotao; Liu, Ning; Li, Xiaoxiang; Huang, Yujie; Chen, Meng; Cai, Hong; Wang, Guangda; Liu, Liangyun; Guo, Wenzhang; Chen, Qi; Li, Liang

doi:10.1016/j.proeng.2017.10.737

Cited by 26 publications

(8 citation statements)

References 12 publications

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“…Bt bh (15) where B, b, h and t means the effective width of the web, the width of the rib, the height of the rib and the height of the web, respectively. For a given panel, parameters b, h and t are constant, but the effective width of the web B changes with deformation progress.…”

Section: Evolution Of Stressmentioning

confidence: 99%

“…From Equation (15), it can be concluded that the top of the rib locates in the inner side (subjected to compressive stress) during the bend and the bottom of the web locates in the outer side (subjected to tensile stress). However, the direction of the Y-direction stress component of the rib near the rib-root depends on the bend radius and the width B.…”

Section: Evolution Of Stressmentioning

confidence: 99%

See 1 more Smart Citation

Electromagnetic Forming Rules of a Stiffened Panel with Grid Ribs

Tan

Zhan

Gao

et al. 2017

Metals

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Electromagnetic forming (EMF), a technology with advantages of contact-free force and high energy density, generally aims at forming parts by using a fixed coil and one-time discharge. In this study, multi-stage EMF is introduced to form a panel with stiffened grid ribs. The forming rules of the stiffened panel is revealed via analyzing the distribution and evolution of the simulated stress and strain in the ribs and web, where the grid-rib panels were decomposed as the flat panel and two panels with uni-directional ribs (ribs only in X direction or Y direction). It is shown that the forming depth is mainly attributed to the forces on the web, although electromagnetic force is applied on both the ribs and the web, especially, large force on the ribs. The ribs are subjected to uniaxial stress parallel to their directions, and the web is subjected to plane stress in the deformation region. Furthermore, the change of the uniaxial stress characteristic in the X-direction ribs is influenced by the electromagnetic force, reverse bend and inertial effect. The plastic deformation mainly occurs in the Y-direction ribs of the deformation region under a three-direction strain state.

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Section: Evolution Of Stressmentioning

confidence: 99%

Section: Evolution Of Stressmentioning

confidence: 99%

Electromagnetic Forming Rules of a Stiffened Panel with Grid Ribs

Tan

Zhan

Gao

et al. 2017

Metals

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“…Therefore, research has been conducted on high-speed forming methods such as electromagnetic forming (EMF) [13,14] and explosive forming (EF) to improve the formability and strength of products [15,16]. The inertia effect and void reduction of sheets with high strain rates can be seen in strain-stress diagrams [17,18].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Formability in Electrohydraulic Forming with and without Bridging Wire

Jang,

Kim,

Kim

2024

Preprint

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Electrohydraulic forming (EHF) can overcome the shortcomings of deep drawing and electromagnetic forming, demonstrating a reduced bouncing effect, formation in narrow areas, and no effect on the electrical conductivity of the blank. In existing EHF experiments, wires are fastened to provide a forming force at variable positions. Therefore, production of uniform products is difficult, and the experimentation is time-consuming and difficult to apply in industrial processes. In this study, wireless and wire-cross EHF were presented to reduce the time required for EHF experiments and produce a uniform forming force. The maximum forming height and formability were evaluated using a 0.5 t SUS430 specimen and free-bulging die. The required experimentation time was measured by comparing each EHF with a conventional EHF. The wireless EHF experiments required the least time and produced a constant forming force. A wire-cross EHF was proposed to compensate for the time required to connect the fully connected wires in a conventional EHF. However, this did not substantially reduce the experiment time. Although wire-cross EHF has a higher energy efficiency than wireless EHF because wires are incorporated, it cannot completely overcome the fundamental problems of EHF. In wireless EHF, two consecutive experiments were performed to produce the same height under an applied voltage of 6 kV. When conducting consecutive experiments, if the experiment is ready for the first time, only the capacitor must be repeatedly charged and discharged while maintaining a constant electrode spacing, so the experiment can be completed faster.

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“…Lai designed and fabricated EMF system for flanging a large-scale aluminum alloy sheet with bore, whose outer diameter, bore diameter, and sheet thickness are 640 mm, 180 mm, and 5 mm [14]. Lai used a large flat spiral coil with an outer diameter of 830 mm to form a Ф1378 workpiece into a partial semi-ellipsoidal shape, and the maximum deviation was no more than 4 mm [15]. Long A demonstrates forming procedure of a large size AA2524-T3 sheet specimen with one-dimensional curvature, which expands application of electromagnetic force and intends to explore a new forming technology for aircraft skin manufacturing [16].…”

Section: Introductionmentioning

confidence: 99%

Enhancing the electromagnetic forming performance of thin-walled sheet metal via a thicker driver: Forming behavior and experimental validation

Xu,

Lai,

Gong

et al. 2023

Preprint

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This paper proposes an innovative electromagnetic forming approach for die-forming of sheet metal parts with a low thickness-to-diameter ratio (0.25%), in which an additional driver sheet was used to improve the forming behavior. Numerical simulations reveal that the conventional EMF method fails to prevent wrinkling defects in thin-walled sheet metal forming, with the severity of wrinkles increasing as the voltage rises. These wrinkles reach a maximum height of 11.3mm and result in inadequate workpiece adherence to the die. To address these challenges, a novel technique is introduced that effectively suppresses wrinkling by enhancing the interaction between the driver sheet and the workpiece. Through a comprehensive evaluation of forming efficiency and wrinkle suppression, an optimal driver sheet thickness of 3mm is determined, minimizing wrinkling to 0.67mm. Compared to the conventional EMF method, the proposed approach yields a fuller and more accurate forming results, closely conforming to the die contour. The process window is defined by analyzing two fundamental process parameters: blank holder force (FBHF) and discharge voltage (Vd). The deformation history of the driver sheet EMF is examined for a high forming quality case with Vd = 12kV and FBHF = 8 kN, resulting in 1.41mm die-fitting gaps. A comparative experimental study demonstrates the effectiveness of the driver sheet EMF technique in producing deep-cavity workpieces with superior forming accuracy. The results include a maximum die-fitting gap of 1.41mm and a maximum wrinkle height of 0.67mm. The proposed driver sheet EMF method exhibits enhanced flexibility and efficiency compared to the conventional EMF, particularly in manufacturing extremely thin-walled sheet metal parts.

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A comprehensive electromagnetic forming approach for large sheet metal forming

Cited by 26 publications

References 12 publications

Electromagnetic Forming Rules of a Stiffened Panel with Grid Ribs

Electromagnetic Forming Rules of a Stiffened Panel with Grid Ribs

Experimental Study on Formability in Electrohydraulic Forming with and without Bridging Wire

Enhancing the electromagnetic forming performance of thin-walled sheet metal via a thicker driver: Forming behavior and experimental validation

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