Research On Tube Magnetic Pulse Welding With Bidirectional Loading Based On Electromagnetic Forming Technology

Electromagnetic forming technology is a processing method for rapid forming of metal workpiece with pulsed electromagnetic force generated by electromagnetic coil.As a high energy forming technology,its development and application in aluminum alloy material forming can effectively realize lightweight,which is significance for promoting energy conservation and emission reduction.Magnetic pulse welding(MPW)is a kind of new solid phase welding technology based on electromagnetic forming.It can realize effective welding between metal materials at room temperature.Meanwhile,it also has the advantages of high speed,high strength and no pollution.Among them,tube MPW has obvious advantages because of the using of solenoid coil with symmetry.However,in traditional tube MPW,a single coil is used to apply radial electromagnetic force to the outer pipe to make it shrink and collide with the inner pipe surface at high speed to achieve welding.This leads to the electromagnetic force applied in a single way and the welding quality is not high enough.Therefore,this paper presents an innovative method of bidirectional loading to realize the welding of inner tube and outer tube by using radial bulged electromagnetic force and radial compressed electromagnetic force.This method can make inner tube and outer tube deform at the same time and collide with each other at high speed to realize welding.In order to achieve the above objectives,the basic principle analysis of tube MPW and simulation will be carried out in order to optimize the electromagnetic force application mode,and realize bidirectional loading pipe MPW to improve the welding quality.The main research process of this article is as follows:Firstly,in order to clarify the driving mode of pipe fitting in tube MPW,the coupling mechanism between transient magnetic field,induced eddy current and radial electromagnetic force received by pipe fitting in traditional tube MPW will be researched.Then,the realization conditions of metal in MPW is analyzed.And combined with the problem of single electromagnetic force application in traditional tube MPW,a specific method of bidirectional loading tube MPW is put forward by introducing a inner coil in inner tube.Secondly,the coupling problem between electromagnetic field and structure field in MPW is briefly introduced.After that,this paper minutely researched the discharge circuit model,electromagnetic field model,and structural field model in bidirectional loading tube MPW.Meanwhile,the modeling and parameter setting of loosely coupled physical model about bidirectional loading tube MPW are described in detail.Finally,the bidirectional loading tube MPW of AA1060 aluminum alloy pipe is studied based on the simulation model.This article mainly analyzed the effects of discharge voltage,capacitance,coil position,and pipe spacing on axial magnetic induction strength,induced current,and radial electromagnetic force on pipe.Furthermore,the influence of the above parameters on the welding effect is analyzed,based on the judgment of speed of outer pipe relative to inner pipe before the collision.The result shows that the higher the discharge voltage and the smaller the capacitance,the more beneficial it is to realize bidirectional loading tube MPW.Moreover,if the coils move too far to the end of the pipe fitting along the axial direction,the collision speed of the middle position of welding zone will be reduced,which is unfavorable to the realization of welding.When the pipe fitting spacing is 2.5mm,the relative speed of collision can meet the welding requirements.At this moment,the rates of relative velocity growth will diminish gradually if the pipe fitting spacing continues to increase.In addition,by comparing the traditional tube MPW and the new method in this paper,the effectively increase of the relative velocity between inner tube and outer tube before collision can be found in the innovative approach.And the distribution of relative velocity along the axis is more uniform than traditional way,which is helpful to improve the quality of tube MPW.Therefore,the innovative method in this paper is a potential optimization scheme,which can contribute to the large-scale industrial application of tube MPW.