JPS56111205A - Method for multipole magnetization on resin magnet - Google Patents

Abstract

PURPOSE:To make it possible to make magnetic field orientation and magnetization alternately in a die, by making use of the gap between magnetic paths and the extent of intensity of the generated magnetic field. CONSTITUTION:Inside a cavity 8 a core 9 of magnetic material is mounted, while outside of it a nonmagnetic plate 10 is mounted. On the outer circuit of the plate, concave parts and convex parts are formed corresponding to the number of poles to be magnetized. Further on the outside of the plate 10, a magnetic plate 11 is mounted which has convex parts and concave parts to mate with the concave parts and convex parts of the plate 10. While an electric current is being sent to form a necessary magnetic field orientation in the cavity, melted resin magnet is injected to fill the cavity, cooled and hardened. Temporarily the strong magnetic field is switched off, then a reverse current is sent to form a feeble magnetic field. At this time, where the gap is narrow higher counter magnetomotive force than the coercive force is applied to magnetize to obtain a polarity reverse to the stage of the orientation, and the magnetization is performed contrary to the initial disposition, and where the gap is sufficient, the counter magnetmotive force is less than the coercive force, so the same polarity as in the stage of orientation is retained. Thereafter the electric current is switched off to take out the molded material. Thus a magnet magnetized on the outer circuit as desired can be obtained.