Analysis and reduction of coil temperature rise in electromagnetic forming

This study proposes an electromagnetic-assisted stamping (EMAS) method with magnetic-force loading at the sheet end in order to control the springback phenomenon. The new method does not change the structure of the mold and does not generate a magnetic force at the sheet corner compared to traditional EMAS. Thus, the new approach could greatly extend the mold lifespan and could be readily adopted in commercial production environments. The effects of technological parameters, such as the distance between the blank holder and die, discharge voltage, and sheet thickness on the springback phenomenon were analyzed. Our results suggest that tangential stress and elastic strain energy both decrease with the increase of discharge voltage. The simulation method accurately predicted the deformation of the sheet during the quasi-static stamping and dynamic magnetic forming processes. The simulation and experimental results both show that as the discharge voltage increases, the bent angle after springback decreases.

Section: Electromagnetic Forming Processmentioning

confidence: 99%

Springback Reduction of L-Shaped Part Using Magnetic Pulse Forming

Cui

Xiao

et al. 2020

“…Typically, the entire process includes three models, the electric circuit model, the electromagnetic field and the mechanical field. The electric circuit model has been studied by Cao et al [28] in detail. For the electromagnetic filed, according to El-Azab et al [12], the spatial form of Maxwell's equations with moving conductor are presented in Equations (1)-(4),…”

Section: Electromagnetic Forcesmentioning

confidence: 99%

Electromagnetic Forming Rules of a Stiffened Panel with Grid Ribs

Tan

Zhan

Gao

et al. 2017

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.

“…The electromagnetic circuit model is based on the EMF system in Cao et al [28], where an additional crowbar circuit is used to effectively reduce the temperature rise of the coil.…”

Section: Establishment Of the Fe Modelmentioning

confidence: 99%

“…Finally, the holder is removed, and the workpiece springback due to unloading can be simulated using the springback model. The electromagnetic circuit model is based on the EMF system in Cao et al [28], where an additional crowbar circuit is used to effectively reduce the temperature rise of the coil.…”

Section: Establishment Of the Fe Modelmentioning

confidence: 99%

“…The measured coil current is shown in Figure 15, and the detailed description of the current characteristic is presented by Cao et al [28]. In order to improve the calculation efficiency of the model, especially the EM model, the current-time curve in the simulation is also idealized, according to the research of Oliveira et al [22].…”

Section: Determination Of the Discharge Time And Deformation Timementioning

confidence: 99%

See 1 more Smart Citation

Guideline for Forming Stiffened Panels by Using the Electromagnetic Forces

Tan

Zhan

Liu

2016

Electromagnetic forming (EMF), as a high-speed forming technology by applying the electromagnetic forces to manufacture sheet or tube metal parts, has many potential advantages, such as contact-free and resistance to buckling and springback. In this study, EMF is applied to form several panels with stiffened ribs. The distributions and variations of the electromagnetic force, the velocity and the forming height during the EMF process of the bi-directional panel with gird ribs are obtained by numerical simulations, and are analyzed via the comparison to those with the flat panel (non-stiffened) and two uni-directional panels (only with X-direction or Y-direction ribs). It is found that the electromagnetic body force loads simultaneously in the ribs and the webs, and the deformation of the panels is mainly driven by the force in the ribs. The distribution of force in the grid-rib panel can be found as the superposition of the two uni-directional stiffened panels. The velocity distribution for the grid-rib panel is primarily affected by the X-directional ribs, then the Y-directional ribs, and the variation of the velocity are influenced by the force distribution primarily and secondly the inertial effect. Mutual influence of deformation exists between the region undergoing deformation and the deformed or underformed free ends. It is useful to improve forming uniformity via a second discharge at the same position. Comparison between EMF and the brake forming with a stiffened panel shows that the former has more advantages in reducing the defects of springback and buckling.