Analytical prediction of Joule heat losses in electromagnetic forming coils
Analytical prediction of Joule heat losses in electromagnetic forming coils
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DOI：
10.1016/j.jmatprotec.2017.03.008
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发表时间：
2017-08-01
影响因子：
6.3
通讯作者：
Tekkaya, A. Erman
中科院分区：
文献类型：
--
作者：
Gies, Soeren;Tekkaya, A. Erman
电磁成形操作中的线圈暴露于机械以及热负载。特别是在大批量生产的情况下，需要在线圈和工艺设计中考虑焦耳热损失引起的热负荷，以防止热应力过大。为此，本文提出了一种计算矩形截面单匝线圈焦耳热损失的解析方法。它考虑了线圈和工件的几何和物理特性以及放电电流的幅值、频率和阻尼特性。虽然简化的方法假设线圈的恒定电导率，但是增强的方法考虑电导率的温度依赖性过程。验证的分析模型是实现使用相结合的实验和数值研究。光纤测量线圈温度被用来验证模拟。每单位长度的焦耳热损失确定与验证的数值模型，然后用于评估的分析方法的预测质量。在本验证程序中分析了不同的导体材料（CuCrlZr、Cu-ETP和EN AW-1050A）、导体几何形状和放电能量。与数值焦耳热预测相比，简化和增强的分析模型的平均偏差分别为13.1%和9.0%。特别是在较高的放电能量的情况下，增强的模型显示出更高的精度，应优于简化的方法。综合考虑复杂性和精确性，该方法是电磁成形过程中加热线圈和工艺设计的有效工具。(C)2017爱思唯尔B.V.保留所有权利。
Coils in electromagnetic forming operations are exposed to mechanical as well as thermal loads. Especially in case of high volume production the thermal loading due to Joule heat losses needs to be considered in the coil and process design to prevent thermal overstressing. For this purpose an analytical approach to calculate the Joule heat losses in a one-turn coil with rectangular cross section is presented. It takes the geometrical and physical properties of coil and workpiece as well as the amplitude, frequency, and damping behavior of the discharge current into account. While a simplified approach assumes a constant electrical conductivity of the coil, the enhanced approach considers the temperature-dependent course of the electrical conductivity. Verification of the analytical model is realized using a combination of experimental and numerical investigations. Fiber-optical measurements of the coil temperature are used to verify the simulation. The Joule heat loss per unit length determined with the verified numerical model is then used to evaluate the prediction quality of the analytical approach. Different conductor materials (CuCrlZr, Cu-ETP, and EN AW-1050A), conductor geometries, and discharge energies are analyzed in this verification procedure. Compared to the numerical Joule heat prediction an average deviation of 13.1% and 9.0% is determined for the simplified and the enhanced analytical model, respectively. Especially in case of higher discharge energies the enhanced model shows an improved accuracy and should be preferred over the simplified approach. Considering complexity and accuracy, the analytical approach is a proper instrument for the thermal coil and process design in electromagnetic forming operations. (C) 2017 Elsevier B.V. All rights reserved.