| 摘要 |
PURPOSE:To obtain a cylindrical magnet of good orientation by enclosing a mixed powder in a space in a mold and applying a magnetic field over the specified value for magnetization after which pressure-molding is performed in a magnetic field under the specified value. CONSTITUTION:A space 6 surrounded by a bottom die 7 and a punch 4 is filled with a mixture of a rare earth magnet powder and a plastic resin binder and a lower core A2, the punch 4 and the bottom die 7 are raised to close up the space 6 tightly. Then, a magnetization power source connected to a magnetization coil 5 is operated to flow a current in a pulse state once or a few times in a short time of 1sec or less and a magnetic field of 15kOe or over is generated thereby performing magnetization. Next, while the space 6 is still close up, an upper cylinder 17 is lowered till the punch 4 reaches the same position as a table 12 and is topped. Then, while magnetic fields of 8kOe or under which are repulsive to each other are generated by magnetic field power sources connected to a lower coil 10 and an upper coil 15 so ast to expand a magnetic line of force radially in the space and to flow it in the punch 4 and the table 12, the upper cylinder 17 operated to perform pressure molding by a non-magnetic upper punch 3. |
