Contactless conveyance of conductive rod by rotating the radial electrodynamic wheel with a spiral structure

Abstract

When a spiral-shaped, radial electrodynamic wheel with an axial pitch is rotated around a conductive rod, the magnetic field produced by the wheel can travel in the axial direction as well as in the circumferential direction of the wheel. Therefore, the rotating spiral wheel produces three-axial magnetic forces: a torque in the circumferential direction, a thrust force in the axial direction, and a repulsive force in the radial direction of the rod. These forces can be used effectively in the contact-free conveyance of the conductive rod. In this paper, the magnetic forces produced by the spiral wheel are modeled theoretically, and the model is verified by FEM and experiment. And, desirable design specifications of the wheel are proposed by analyzing the influences of the pitch angle and the number of permanent magnets that govern the characteristics of the spiral wheel. However, the only parameter that influences the forces generated by the wheel is the rotation speed of the wheel. So, a control algorithm that varies only the rotating speed of the wheel to convey the conductive rod is proposed, and its feasibility is verified by application to a constructed set-up.