平板集磁器结构对涡流分布与集磁效果的影响规律

Influence of the Structure Parameters of the Flat Field Shaper on the Eddy Current Distribution and Magnetic Concentration Effect

电磁脉冲焊接技术在异种金属连接领域展现出广阔的应用前景,集磁器是电磁脉冲焊接系统中的重要组件,可以增强焊接区域局部磁场,改善电磁力分布,提高电磁能量利用率。该文以与多匝线圈配合使用的平板集磁器为研究对象,探究平板集磁器结构与集磁效果的对应关系,分析集磁器缝隙面夹角α对涡流分布的影响规律,提出漏电流和有效电流,并基于电路-磁场耦合的仿真模型计算集磁器的电流幅值及其有效电流比例,采用不同结构特征(锐角、直角和钝角)的集磁器开展铜板与铝板的电磁脉冲焊接实验。结果表明:集磁器缝隙面涡流流向存在分叉现象,根据电流作用于焊接与否,可将其分为有效电流和漏电流两部分,集磁器的上孔直径通过影响有效电流比例改变集磁效果。随着上孔直径增大,集磁器感应产生的总电流降低,但集磁器缝隙面夹角α同时也下降,有效电流比例会提高,所以集磁效果先升后降;当α为锐角时,有利于提高集磁效果,且当α为45°时,集磁效果最佳。相同电压下,采用锐角集磁器所获得的焊接样品抗拉强度最高,直角集磁器次之,钝角集磁器最低。该文可为电磁脉冲焊接系统中集磁器的设计提供实验依据和科学支撑。

Electromagnetic pulse welding(EMPW)technology has broad application prospects in the field of dissimilar metal connecting.Field shaper is an important part in the EMPW system.However,there are few researches on the influence of the structure of flat plate field shaper on its wording efficiency by changing the distribution of eddy currents.Therefore,the relationship among the structural parameters,eddy current distribution and wording efficiency of field shaper was explored from the basic principle of field shaper.The flat field shaper used with multi-turn coil was taken as the research object.The circuit-magnetic field coupling model of EMPW plates was established by COMSOL Multiphysics.Reflected the wording efficiency of the field shaper by calculating the maximum instantaneous magnetic flux density on the surface of the plate to be welded.The structural parameters that affected the effectiveness of the field shaper include height,upper and lower surface diameter,upper and lower hole diameter and gap angleα,The angleαwere jointly determined by the upper and lower hole diameters.When the coil and sample to be welded were confirmed,the diameter of the upper and lower surfaces and the diameter of the lower hole were determined accordingly,which were 200 mm,20 mm and 10 mm respectively according to the application scenarios of EMPW.When the diameter of the upper hole was 10 mm.The simulation result showed that as the height of the field shaper increased,the cancellation effect of the magnetic flux density generated by the induced eddy currents on the upper and lower surfaces of the field shaper gradually weakened,but the eddy current loss increased.So the working efficiency of field shaper first increased and then decreased with the increased of height,and it was the best at a height of 10 mm.There was bifurcation phenomenon of eddy current in the field shaper gaps,it could be divided into two parts:effective current and leakage current,and the effective current can be used for welding.The angleαhad an important impact on the selection of the current path on the side of the gaps,which decided the proportion of effective current.The proportion of effective current continuously increased with the decrease of the angleα.When the height and lower hole diameter were both 10 mm,as the upper hole diameter increased,the total current decreased and the proportion of effective current continuously increased.So the efficiency of field shaper showed a trend of increasing first and then decreasing.When the upper hole diameter was better than that of lower hole,the angleαwas an acute angle,the overall magnetic collection effect was better.And whenα=45°,the efficiency of field shaper was the best.To verified the simulation results,the EMPW platform suitable for copper plate and aluminum plate was established,and different structural field shaper(acute angle,right angle and obtuse angle)were made.Welding experiments,tensile test and peeling experiments were carried out.The results showed that the tensile strength of the sample increased with the increased of voltage.The copper-aluminum sample welded with a sharp angle field shaper got the highest tensile strength,the largest effective welding area and the best welding effect.The welding effect of the right angle field shaper was middle,and the obtuse angle field shaper was the worst.The following conclusions can be drawn from the simulation and experiments:(1)As the height of the field shaper increases,the working efficiency fist increasing and then decreasing,and there is an optimal parameter for the height of the field shaper.(2)There was bifurcation phenomenon of eddy current in the field shaper gaps,and it’s divided into leakage current and effective current,the angle of field shaper gaps influence the current path selection and the ratio of effective current a lot.(3)As the upper hole diameter of field shaper increases,the total current decreases and the proportion of effective current continuously increases.Therefore,the field shaper effect shows a trend of increasing first and then decreasing.