YOKE INTEGRATED MAGNET AND ITS MANUFACTURING METHOD

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PROBLEM TO BE SOLVED : To provide a yoke integrated magnet which does not require a complicated process to inject an adhesive, does not cause a vibration and a fluctuation during high-speed rotation, and does not have the possibility of atmosphere contamination. SOLUTION : A ring-shaped bonded magnet is obtained by injecting a rare earth alloy magnetic-powder together with a crystalline thermoplastic resin binder in a mold at a temperature lower than a temperature-drop crystallization temperature of the thermoplastic resin binder by 50°C to 100°C. After the bonded magnet is put into a ring-shaped back yoke, it is heated to a temperature higher than the temperature-drop crystallization temperature by 20°C to 40°C. Then, the bonded magnet is cooled to a temperature lower than the temperature-dropping crystallization temperature at a cooling rate over 20°C/min. COPYRIGHT : (C)2009, JPO&INPIT