Investigation on Electromagnetic Welding (EMW)for Tubular Jobs using FEA

Abstract

Electromagnetic Welding (EMW)/Magnetic Pulse Welding (MPW) is an effective and successful welding technology for joining two dissimilar metals, wherein bonding is accomplished by penetration of material into each other. It is a non-contact, cold solid state welding process which is carried out under very high impulsive force. It provides efficient results to the manufacturer like leak proof joint between similar or dissimilar metals which are very difficult to achieve by other traditional joining technology. EMW uses magnetic field around the coil and tube/plate which generates the magnetic pressure on the flyer tube/plate to get welded with the base tube/plate.
In the present work, a 3D numerical simulation has been performed to predict the distribution of magnetic field and pressure in the desired region of the tubular jobs using coils with and without field shapers in electromagnetic welding (EMW). For finite element (FE) simulation, single-turn and multi-turn (disk type) coils are considered to analyze the effects of field shapers with varying material combinations in ANSYS MAXWELL environment. The change in magnetic field distribution on the outer peripheral region of the flyer tube along axial direction with and without field shaper is graphically shown and compared. Also, variation of magnetic pressure on the flyer tube with respect to increasing voltage and time is compared individually for various material combinations of ST/MT coil and field shaper.
Further, the study presents a three-dimensional (3D) coupled electromagnetic-structural simulation of MPW on tubular jobs. The obtained transient magnetic field and presure in electromagnetic model is sequentially coupled to the mechanical model to predict the deformations occurring on the mating members. Results in the form of changes in impact velocity, shear stress and effective plastic strain induced on the outer wall of the flyer tube with varying process parameters, via. input voltage and initial angle of taper of inner solid plug during welding simulation is graphically shown. Based on the results of the coupled FE simulation, a weldability window for effective welding of tubular jobs is proposed.
The presented results can be utilized to design an effective field shaper for single/multi -turn coils with improved efficiency in EMW of tubular jobs. The suggested weldability window emphasizes the range of process parameters which can decrease the time and cost in the industrialization process.