Production manner of magnetic encoder, magnetic field injection molding device for multipolar magnet, and die for multipolar magnet

摘要

PPROBLEM TO BE SOLVED: To provide a magnetic encoder capable of appropriately detecting magnetic forces. PSOLUTION: The magnetic encoder 16 includes both a ring-like multi-pole magnet 23 in which magnetic poles are alternately arranged in its circumferential direction and a slinger 24 for housing the multi-pole magnet 23. The multi-pole magnet 23 includes both magnetic powder and a resin. The multi-pole magnet 23 is produced, while generating magnetic fields in axial directions at the time of injection molding, by a magnetic field injection molding machine for multipole magnets provided with a metal mold part; an injection part; and a coil. In the metal mold part, metal molds to be arranged inside the inner diameter of a cavity, which forms an external shape, among metal molds constituting the cavity are constituted of a nonmagnetic material, and metal molds to be arranged in axial directions of the cavity are constituted of a magnetic material. The injection part injects a magnet material into the cavity. The coil generates magnetic fields in axial directions in the metal mold part when the injection part injects the magnet material into the cavity. PCOPYRIGHT: (C)2008,JPO&INPIT