Study On Tube Electromagnetic Bulging With Combination Coil

Electromagnetic forming is a kind of high-energy-rate forming technologies, using the Lorenz forces produced during pulse discharge to form metal workpieces. Electromagnetic forming can be applied in the fields of aviation, space, automobile manufacture and so on. Because forming process is coupled by many fields. Electromagnetic forming theory and technics research are not very perfect. At present, the electromagnetic forming technology is mainly applied in tube forming. In this thesis, the dynamic characteristic and technics parameters of electromagnetic tube bulging with combination coil are systematically studied by numerical simulation and experiments.The basic theory is provided for the finite element numerical simulation of the tube's deformation, by analyzing the finite element method of electromagnetic tube bulging firstly. By finite element simulation of electromagnetic tube bulging with combination coil with ANSYS software, the time space distribution of magnetic pressure is gotten. The uneven distribution coefficient of radial displacement(S) is defined as the ratio of top radial displacement and center radial displacement which is relative to the single coil, which is used to evaluate the extent of uneven distribution of radial displacement. When the coil turns of a single coil are 15, the requirement of uniform forming and the critical relative length are presented. When the tube's relative length L<0.91, top deformation of tube is larger than center deformation of tube which is relative to the single coil; When L>0.91,top deformation of tube is smaller than center deformation of tube which is relative to the single coil; When L=0.91,top deformation of tube is equal to center deformation of tube which is relative to the single coil approximately.The law of Electromagnetic tube bulging with combination coil is investigated by numerical simulation and experiments, and the regularity of magnetic pressure distribution and deformation is studied. The effect law of structural parameters(coil distance and coil turns) and discharge parameters of deforming system on electromagnetic bulging with combination coil are analyzed. The results show that: interrelationship of two coils is weaken with the coil distance is increasing, radial magnetic pressure of tube center and symmetrical point is equal approximately, maximum radial displacement is almost a constant. With the increasing of coil turns, final deformation is decrease, deformed region is increase. Radial displacement is linear increasing with the increase of discharge voltage, increase firstly and decrease lately with the increase of discharge frequency. There is an optimum discharge frequency for the radial deformation(which is about 9.82 kHz in this thesis).The numerical simulation results of tube deformation agree well with the experiment results, so the former can instruct and partially replace the later.