| 摘要 |
PURPOSE:To improve production efficiency by using a mold for injection molding having a plurality of molding spaces, in which magnets for generating magnetomotive force are provided on outside of yokes, and permanent magnets for forming repulsion magnetic circuit are provided between the yokes. CONSTITUTION:A mold has a plurality of cavities 51-54 inside of a base 7 made of soft magnetic material, the cavities being provided with magnetic cores 61-64, respectively, inside thereof. Permanent magnets 11 and 12 for generating magnetomotive force and yokes 31, 32 are placed at the positions corresponding to the magnetic poles on the periphery of the cavity 5. Between the yokes, permanent magnets 21 and 22 are placed for forming repulsion magnetic circuit. Further, non-magnetic spacers 41 and 42 are placed outside of the magnets 21 and 22. The cavities 52-54 are also surrounded by a similar structure to that of the cavity 51. Mixture mainly consisting of ferromagnetic powder and thermoplastic resin is injection molded in the mold. The peripheral surface of the molded body thus obtained is magnetized in the same direction with the orientation by the magnetic field. Thus, the production efficiency can be improved. |
