A Method for Calculating Electromagnetic Field of a Spiral Type Induction System for Magnetopulse Processing of Non-Magnetic Metal Strips With a Ferromagnetic Shield

Abstract

Pulsed currents and magnetic forces of an induction system with a spiral winding and a ferromagnetic shield for processing non-magnetic thin-sheet metal strips in order to create magnetoplastic, electroplastic effects due to eddy currents are studied. Under the strip there is the ferromagnetic shield, and above it – spiral winding. The aim of the work is to develop an analytical method for calculating transients of pulsed currents in an electric circuit with the induction system and a capacitor charged to certain voltage taking into account influence of the ferromagnetic shield to perform investigation of time-varying magnetic field. Electromagnetic parameters of the inductor are determined by computer simulation using the finite element method in the mode of harmonic currents. Current transients in the electric circuit are calculated using known in theoretical electrical engineering mathematical dependences and distribution of current density and magnetic forces in the strip is calculated by the finite element method in the mode of transients. Influence of the ferromagnetic shield on electromagnetic processes in the induction system for the set ranges of strip’s thickness, its electrical conductivity and current frequency is established. Electromagnetic force between the spiral winding and the strip, the current density in the strip, as well as the moments of time at which the current and force have maximum values are studied. References 14, figures 6, tables 2.

Analytical determination of a quasi-stationary electromagnetic field created by magnetic moments and eddy currents in conducting half-space

“… m e r r m e H (15) It follows from this that the critical points of the field in the plane y = 0 are located at the points 2 h x   of the axis parallel to the direction of the magnetic moments. These are critical points of the hyperbolic type (saddle) S, through which the separatrixs pass -the field lines (shown by bold lines), which separate areas with different character of field formation.…”

“…In this case, at  = 0.3, for example, for brass products ( = 1,  = 1.2510 7  -1 m -1 ) at h = 0.03 m calculations can be performed for frequencies f = /2  125 Hz. In equipment for exposure to a strong field to improve the mechanical properties of metal products [15,16], the distance is h = 0.01-0.02 m. In this case, at h = 0.01 m for aluminum ( = 1,  = 3.7110 7  -1 m -1 ) permissible frequencies are f  380 Hz. It should be noted that the devices for the technological processes indicated here are examples of objects in the development of which the calculation methods under investigation can be used.…”