| 摘要 |
A tone wheel constituting a rotation detection magnetic encoder in combination with a magnetic sensor fixed onto a stationary side member, the tone wheel comprising a metal reinforcing ring fitted in a rotary side member and a circular multipolar magnet fixed to the metal reinforcing ring. the circular multipolar magnet is made of a plastic magnet of a circular resin molded product which contains a magnetic powder therein and is magnetized with a number of S and N poles alternatively provided along its circumference. The metal reinforcing ring has a mating portion with which a part of the circular resin molded product mates. The circular resin molded product is a molded product integrally combined with the metal reinforcing ring in which a part of the circular resin molded product mates with the mating portion of the metal reinforcing ring, and is made by charging a melt resin material into a forming die in which the metal reinforcing ring is disposed and hardening the melt resin material. The metal reinforcing ring has at its edge a bent portion which is enwrapped with a part of the circular resin molded product, and the mating portion is provided at the bent portion.
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