轴向压缩式管件磁脉冲胀形电磁结构耦合机理及材料成形性能研究

Electromagnetic forming, which can significantly improve the metal formability, plays an important role in solving the difficulty in aluminum alloy processing. However, the main object of electromagnetic tube expansion is usually aiming at increasing the coupling efficiency between the driving coil and the workpiece. As a result, the workpiece is mainly expanded and the wall thickness reduces seriously. To improve the material formability, the electromagnetic tube expansion with axial compression is proposed in this project. The basic idea of this method is to optimize the structure of the driving coil so as to obtain the axial and radial electromagnetic force. Because of the axial compression, the wall thickness thinning reduces and the material formability improves. The coupled electromagnetic-structural mechanism, distribution of electromagnetic force, and material formability of electromagnetic tube expansion with axial compression will be studied in this project. Based on four different finite element models, the interaction among the spatiotemporal distribution of electromagnetic field, the magnitude and direction of the electromagnetic force, the motional electromotive force, the workpiece displacement, and the forming behavior will be elucidated. Moreover, the wall thickness and fatigue performance of the deformed tubes under different electromagnetic force will be analyzed. It is expected to reveal the coupled electromagnetic-structural mechanism in the electromagnetic tube expansion process and clarify the effect of loading mode on the material formability. With these researches, we hope this project will provide relevant theoretical and experimental basis for electromagnetic forming.

电磁成形是一种高速率脉冲成形技术，是突破目前轻质合金加工制造瓶颈的重要途径。然而现有管件磁脉冲胀形，通常仅采用径向电磁力单向加载，导致工件壁厚减薄、强度降低，无法满足现代工业对高强度及高性能零件的需求。为此，本项目采用径向电磁力与轴向电磁力同时加载的施力方式，创新地提出轴向压缩式管件磁脉冲胀形方法; 轴向压缩可使工件材料及时补充到胀形减薄区，能有效减小工件壁厚的减薄量，提高工件成形性能。项目将开展轴向压缩式管件磁脉冲胀形电磁结构耦合机理、电磁力分布规律及材料成形性能等三个方面的研究；拟采用四组模型分离电磁成形中的强耦合参数，重点阐明轴向压缩式管件磁脉冲胀形过程中电磁场时空分布、电磁力大小和方向、运动电动势与工件应力应变、变形行为之间的内在关联；进一步揭示轴向压缩式管件磁脉冲胀形时不同加载形式下的轴向电磁力与径向电磁力分布对材料成形性能的作用机理，为深入研究电磁成形提供相关理论和实验依据。

电磁成形是一种高速率脉冲成形技术，是突破目前轻质合金加工制造瓶颈的重要途径。然而现有管件磁脉冲胀形，通常仅采用径向电磁力单向加载，导致工件壁厚减薄、强度降低，无法满足现代工业对高强度及高性能零件的需求。为此，本项目采用径向电磁力与轴向电磁力同时加载的施力方式，创新地提出轴向压缩式管件磁脉冲胀形方法；轴向压缩可使工件材料及时补充到胀形减薄区，能有效减小工件壁厚的减薄量，提高工件成形性能。项目开展了轴向压缩式管件磁脉冲胀形电磁结构耦合机理、电磁力分布规律及材料成形性能等三个方面的研究；阐明了待成形工件的电磁力分布要求与驱动线圈结构的关联性，明确了轴向电磁力与径向电磁力双向加载方案，完善了轴向压缩式管件磁脉冲胀形方法；建立了合理的松散耦合模型、形变耦合模型、速度耦合模型及物理耦合模型等四组对比模型，阐明电磁参量与结构参量之间的内在关联，揭示了管件磁脉冲胀形过程中电磁结构耦合机理；揭示了轴向电磁力与径向电磁力分布对铝合金管件成形性能的作用规律。通过进一步深入研究，延伸出以下研究成果：提出轴向压缩式管件磁脉冲胀形方法解决管件加工存在的问题；提出电磁成形过程的电磁-结构耦合改进算法提升计算效率与精度；提出凹型电磁力加载解决管件电磁胀形轴向变形非均匀问题；提出耦合冷却式柔性电磁成形解决电磁力柔性加载及驱动线圈温升问题；提出轴向-径向电磁力分时加载实现电磁圆孔翻边。本项目的开展，推动了电磁成形工业化应用进程，支撑我国前沿制造产业向智能、高效和清洁的方向变革。