| 摘要 |
PURPOSE:To suppress the concentration of surface magnetic flux densities to the end sections of a permanent magnet by forming a ferromagnetic coating film on the principal surface of the magnet body in such a way that the film at the end sections is made thicker than at the central part. CONSTITUTION:In order to rectify the uneven surface magnetic flux density of a magnet blank, the film thickness of a ferromagnetic coating film 2 formed on a permanent magnet body 1 at the end sections 3 on the principal surface of the body is, preferably, made 1.5 to 10 times as thick as that at the central part 4. When the film thickness of the film 2 at the end sections 3 is 1.5-10 times thicker than that at the central part 4, the rise of the permanent magnet at the end sections 3 can be suppressed to a height (y), since the surface magnetic flux density of the permanent magnet body 1 becomes smaller as the film thickness of the film 2 becomes thinner. When the film thickness of the film 2 is controlled in such way, the (x-y)/x becomes about 5-30% and the concentration of magnetic fluxes to the end sections can be suppressed by 5-30%. As a result, the area of the principal surface having a uniform magnetic flux density is also increased. |
