| 摘要 |
PURPOSE:To provide a technique of manufacturing a covered magnet wherein a permanent magnet is correctly set at a required position. CONSTITUTION:A first process wherein polytetrafluoroethylene powder 6 is filled into a mold 5 and compressed by a prescribed pressure into a solid circular cylinder 10, a primary burning process wherein the solid molded body 10 is burned by heating it along a certain temperature curve, and a boring process wherein a magnet inserting hole 13 is bored in the burned body 10 are provided. Furthermore, a process wherein a permanent magnet 2 is inserted into the inserting hole 13, a hole plugging process where the magnet inserting hole 13 is stopped up with a previously formed plug 15 of polytetrafluoroethylene, and a secondary burning process where the molded body 10 equipped with the permanent magnet 2 is burned again by heating it along a certain temperature curve are provided. By this setup, a permanent magnet can be correctly held at a prescribed position, and a polytetrafluoroethylene layer can be formed uniform in thickness. Therefore, when a covered magnet formed through this method is used as the stirrer of a magnetic stirring machine, a regular stirring operation can be carried out and the stirrer can be elongated in service life. |
