Electromagnetic Levitation System for Thin Steel Plate Using Electromagnets and Permanent Magnets (Fundamental Consideration on Optimal Placement to Suppress the Deflection of Steel Plate)

In thin steel plate production lines widely used for various industrial products, thin steel plates are contact-conveyed by rollers in the conveying process. Owing to this conveying method, the quality of the surface deteriorates, resulting in degradation such as scratches or peeling of the plating layer of the thin steel plate. As a solution to these problems, we studied a noncontact magnetic levitation system for a rectangular thin steel plate using electromagnets and permanent magnets. We determined the optimal placement of permanent magnets using a genetic algorithm (GA), which searches for placements using an evaluation function. However, although the evaluation function was defined by the GA, since only a basic examination was conducted, the weight coefficient used in the evaluation was insufficient. In this paper, we changed the weight coefficient of the evaluation function and compared and analyzed the results of the permanent magnet arrangement determined by the GA. It is possible to obtain an optimum permanent magnet arrangement in which the levitation stability is improved by experimentally verifying the effects of the maximum deflection and average deflection on levitation performance. The levitation experiment is carried out using each weight coefficient for permanent magnet arrangement. Then, the levitation stability is evaluated.