A New Method Of Controling Welding Hot Cracking By Welding Based On Electromagnetic Forces

Basing on the fundamental principle of electromagnetic induction and the analysis of flat plate welding structures'behavior of hot cracking, a new method of controlling welding hot cracking by welding based on electromagnetic forces is put forward. The effects of various circuit parameters and geometric parameters on magnetic forces acting on the workpiece are analyzed using finite element method. And the results of the analysis are expected to providing a theoretical guide for the improvement of the experimental facility and the optimum design of the electromagnetic coil.The numerical results indicate that the peak values of magnetic forces increase with the increase of the charging voltage, and the same tendency for the increases of the capacitance. When the workpiece is larger than the electro-magnetic coil, the magnitudes and distributions of the magnetic forces almost have no changes with the radius of the workpiece increasing. The magnitudes of the axial magnetic forces increase strikingly with the reducing of the space between the coil and the workpiece, but the radial forces change little, and the range of action tends to diminish and concentrate. A wider width of the conducting wire leads to a sharp increase in peak values of axial and radial forces, while the distributions of them have no change. With the increases of the inner diameter of the coil, the range of action shrinks, and when the outer diameter increases, an adverse change is obtained.Moreover, the effects of temperature on characteristics of magnetic forces are also studied in this dissertation. The numerical results are presented as follows: A constant and uniform temperature of the workpiece has no effects on the distribution of magnetic forces, however, it can change the magnitudes of them. When the temperature distribution on the workpiece is non-uniform, the eddy current induced by the workpiece flows along low temperature areas, and causes a non-uniform distribution of magnetic forces. The general tendency is that the range of action of magnetic forces moves to low temperature areas.Based on the FEM results, the mechanism of Welding with Electro-magnetic Forces is initially presented as follows: Magnetic forces exert compression strain...