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轴径双向加载式金属管件电磁—电液复合成形技术数值模拟与实验研究

Numerical Simulation and Experimental Study on Electromagnetic-Electrohydraulic Composite Forming Technology of Metal Tube under Axial-Radial Bidirectional Loading

【作者】 张毅

【导师】 李亮;

【作者基本信息】 华中科技大学 , 电气工程, 2022, 硕士

【摘要】 轻量化技术是航空航天、交通运输等领域提高运载器件性能、实现节能减排的重要途径,使用铝合金等轻质合金材料对于实现轻量化具有现实意义。目前,电液成形、电磁成形等高速成形技术是提升轻质合金材料成形性能的重要手段。然而前者面临胀形较大时减薄和撕裂等问题;后者存在电磁力随工件变形会迅速衰减而难以多次加载等问题。为此,本文以6061铝合金管件为研究对象,提出了一种轴径双向加载式金属管件电磁-电液复合成形新工艺,通过轴向电磁载荷与径向电液载荷的时空配合促进材料流动,提升了管件的胀形能力与贴模性能。通过实验与仿真相结合的手段,在管件变形行为与调控机理等方面开展了系统研究,相关研究成果对于突破轻质合金管件成形技术的局限性、拓展其工业应用具有重要的学术价值和现实意义。首先,阐释了电磁-电液复合成形技术的原理并建立了较完善的理论分析模型,进而建立了能够分析电磁推送力的COMSOL仿真模型和能够进行电液胀形流固耦合计算的LS-DYNA模型,并通过上述模型间的耦合实现了复合成形系统的建模,在保证精度的同时提高了运算效率,为管件动态变形行为研究提供了分析手段。其次,搭建了包含脉冲电源系统选型和电磁-电液装置搭建在内的复合成形系统实验平台,并验证其重复性。此外,通过仿真模型进行了矩形金属丝爆炸时,电液冲击载荷及其作用下管件变形过程的动态分析,为后续系统性研究奠定了基础。随后,为了研究新方法对管件胀形能力的提升效果与调控机制,本文采用实验与仿真分析相结合的方法对铝合金管件进行了变形特征与机理研究。并发现相较于单一电液胀形,新方法下管件胀形深度提升了27.6%;仿真在胀形深度、轴向流动、壁厚减薄和成形轮廓方面均与实验较好吻合、可靠性高,并根据电液载荷作用结束时间将成形过程分为两个阶段进行动态行为分析。最后,为了提升管件与模具倒角处的贴合程度,实现管件形貌的有效调控,本文进一步地对该方法如何改善管件贴模性能进行系统分析。探究了电磁-电液高速冲击载荷的时序配合、推送力脉宽两个因素对贴模性能的调控机理,实现了轴径载荷的高效配合,在改善贴模性能的同时能够大幅节省推送耗能;进而通过多步成形验证了其后续加工性能,并最终实现了18.28 mm大胀形深度下0.02 mm高贴模精度管件。

【Abstract】 Lightweight technology is an important way to improve the performance of vehicles and achieve energy saving and emission reduction in the fields of aerospace and transportation,and the use of aluminum alloy and other lightweight alloy materials is of practical significance to achieve this.At present,the high-speed forming technologies,such as electro-hydraulic forming and electromagnetic forming,are important means to improve the forming performance of lightweight alloy materials.However,the former faces problems such as thinning and tearing during larger expansion,while the latter is difficult to load for several times since the electromagnetic force decays rapidly with the deformation of the workpiece.To solve this,this paper takes 6061 aluminum alloy tube forming as the research object,and proposes a new composite forming process composed of electromagnetic and electrohydraulic forming processes for tube expansion.The space-time cooperation between radial electrohydraulic load and axial electromagnetic load at the tube end promotes the flow of material during the forming process,and enhances the expansion capacity and die-fitting performance of the tube.Through a combination of experiments and simulations,systematic research has been carried out on the tube deformation behaviour and regulation mechanism.The relevant research results have important academic value and practical significance for breaking through the limitations of aluminum alloy tube forming technology and expanding its industrial application.Firstly,the principle of electromagnetic-electrohydraulic composite forming technology is explained and a better theoretical analysis model is established.Then,the COMSOL simulation model,which can analyse the electromagnetic pushing force,and the LS-DYNA model,which can perform the electro-hydraulic expansion flow-solid calculation coupling,are established.The model of the composite forming system is realized through the coupling between the above two models,which can improve the computing efficiency while ensuring the accuracy,and provide the analysis method for the study of tube dynamic deformation behaviour.Secondly,the experimental platform of composite forming system including pulse power system selection and electromagnetic-electrohydraulic device construction is built and its repeatability is verified.In addition,the dynamic analysis of electro-hydraulic impact load and deformation process of the tube under the action of rectangular wire explosion is carried out by simulation model,which laid the foundation for the subsequent systematic research.Then,in order to study the effect and control mechanism of the new method on the expansion capacity of the tube,the deformation characteristics and mechanism of the aluminium alloy tube were investigated using a combination of experimental and simulation analysis.It is found that the new method increases the expansion depth of the tube by 27.6%compared to the single electro-hydraulic expansion.The simulation is compatible with the experiment in terms of expansion depth,axial flow,wall thickness reduction and forming profile,and is highly reliable.The forming process is divided into two stages according to the end time of the electro-hydraulic load for dynamic behaviour analysis.Finally,in order to improve the fitting of the tube to the chamfer of the mould and to achieve effective control of the tube shape,this paper further analyses how the method can improve the die-fitting performance of the tube.The time sequence of the electromagneticelectrohydraulic high-speed load and the pulse width of the pushing force have been explored to control the die-fitting performance,and the efficient fitting of the axial diameter load has been achieved,which improves the die-fitting performance and saves the pushing energy.The subsequent machining performance was verified by multi-step forming,and the result is a tube with a high die-fitting accuracy of 0.02 mm at a large bulging depth of18.28 mm.

  • 【分类号】V26;V46
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