Impact of Metal Thickness and Field Shaper on the Time-varying Processes during Impulse Electromagnetic Forming in Tubular Geometries
Impact of Metal Thickness and Field Shaper on the Time-varying Processes during Impulse Electromagnetic Forming in Tubular Geometries
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DOI：
10.3938/jkps.59.3560
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发表时间：
2011-12-01
影响因子：
0.6
通讯作者：
Niayesh, Kaveh
中科院分区：
文献类型：
--
作者：
Gharghabi, Pedram;Dordizadeh B, Peyman;Niayesh, Kaveh
脉冲电磁成形是一种有效的成形技术，广泛应用于金属板料和管材的成形和连接。该技术可用于不同的目的;然而，该技术的所有应用中的主要原理是相同的。在过去的几十年中，工程师，特别是汽车行业的工程师，一直被吸引到形成轻质和低延展性的板材或管状金属。在该方法中，工作线圈位于管状工件的内部或外部。当脉冲电容器通过快速开关放电时，强电流通过线圈，并且由于高度时变的磁场，在工件中感应出电流;因此，对金属管施加过大的力。取决于线圈的位置，在管状工件的内部或外部，合力可能导致工件膨胀或收缩。系统的整体性能受工件的厚度和材料特性以及场整形器的几何参数的显著影响。本文采用基于有限元的数值模拟方法对脉冲电磁成形过程进行了研究。通过改变系统的几何结构和配置，不同的影响参数，如工件的厚度和场整形器的几何形状对整个系统的性能的影响进行了研究。它必须;应当注意，由于工件的变形，系统的电参数如互感是时间相关的。如果要考虑这些随时间变化的影响，则必须计算每个时间步长在工作线圈的不同位置处施加的力引起的应力和应变率以及工件的合成变形。使用磁场测量的实验装置，我们验证了模拟结果，并建立了简单的指导方针，设计脉冲电动势系统的管状几何形状。
Impulse electromagnetic forming is an effective and powerful technique widely used for reshaping or joining metallic sheets and tubes. This technique can be employed for different purposes; however, the main principle in all of the applications of this technique is the same. During the last decades, engineers, especially those in the automotive industry, have been attracted to forming lightweight and low-ductility sheet or tubular metals. In this method, a work coil is located inside or outside of the tubular workpiece. When a pulsed capacitor is discharged through a fast acting switch, an intense current passes through the coil and due to the highly time-varying magnetic field, a current is induced in the workpiece; consequently, an excessive force is applied to the metallic tube. Depending on the location of the coil, inside or outside of the tubular workpiece, the resultant force could cause the workpiece to expand or contract. The overall performance of the system is considerably influenced by the thickness and the material properties of the workpiece and by the geometrical parameters of the field shaper. In this paper, simulations based on the finite element method (FEM) are used to study the impulse electromagnetic forming (EMF) process. By changing the geometry and the configuration of the system, the impact of the different influential parameters, like the thickness of the workpiece and the field shaper's geometry on the performance of the whole system have been studied. It must; be noted that because of the deformation of the workpiece, the electrical parameters of the system like the mutual inductance, are time dependent. If these time-variant effects are to be taken into account, the stress and the strain rates caused by the exerted force at different positions of the work coil and the resultant deformation of the workpiece must be calculated for each time step. Using magnetic field measurements on an experimental set-up, we verified the simulation results and established simple guidelines for designing impulse EMF systems for tubular geometries.