The Research Of Tube Electromagnetic Attractive Forming Behavior Based On A Dual-coil System

Electromagnetic forming(EMF)is a special forming method with high energy and high speed for metal material by using pulsed electromagnetic force,which has been applied to sheet and tube forming in aerospace,automobile manufacturing and other fields.At present,the theory and method of taking electromagnetic repulsion force as forming force have been widely studied,while the forming method based on electromagnetic attraction is less studied.In practical application,the electromagnetic forming technology based on repulsive force is difficult to be applied in dent repair,disassembly of press-fit joints and bulging of small tube due to the limitation of operating space.The electromagnetic forming technology based on attractive force can make up for these shortcomings,and provides an effective way to further expand the application of electromagnetic forming technology.To solve the problems of low forming ability and poor controllability in existing attraction forming methods,this paper presents a new attraction forming method based on a dual-coil system for tube(AA6061-0)forming.On this basis,the numerical analysis,device design and experimental study of tube attraction bulging are systematically carried out.The relevant research results can provide theoretical and practical value for promoting the development and application of electromagnetic attraction forming technology.Firstly,the basic principle and realization method of tube attraction forming based on a dual-coil system are introduced in detail,and the control mechanism of inner and outer coils on the distribution of eddy current and magnetic field in tube forming process is clarified.On this basis,considering the existing conditions of pulsed power supply in the laboratory,an experimental system for tube attraction forming of a dual-coil system with controllable time sequence was designed.Secondly,the mathematical models of circuit,electromagnetic field and structure field in tube electromagnetic bulging system are described.Based on the finite element simulation software COMSOL Multiphysics,the multi-physical field modeling and coupling solution of tube forming process under double coils are realized.On this basis,the variation rules of parameters such as magnetic field,eddy current,electromagnetic force and tube deformation during the forming process are explored.The mechanism of attraction generation and control under double coils is further clarified,and the validity and feasibility of the scheme is demonstrated.Finally,taking 6061-O aluminium alloy with a diameter of 35 mm and a thickness of 1mm as the experimental object,an experimental platform for tube electromagnetic bulging was established.The electromagnetic attraction forming experiments under different discharge parameters were systematically carried out.The effects including discharge voltage,discharge timing and crowbar circuit on tube forming were investigated,and the numerical analysis result was verified.On this basis,the validity of further improving the forming ability of tube based on multiple discharge mode is proposed and demonstrated.