| 摘要 |
PURPOSE:To make it possible to close a cover completely by a method wherein a ferromagnetic plate, having the hole communicating to another hole, is buried on the side of a magnetic pole surface, the diameter in one direction of the hole is long, and the diameter of a ferromagnetic protrusion in the direction orthogonally intersecting the above-mentioned direction is formed to be approximately equal to that of a ferromagnetic protrusion. CONSTITUTION:A permanent magnet 1 has an annular plate shape, a hole 1a is provided ranging from one magnetic pole surface (a) to the other magnetic pole surface (b), an annular plate-like ferromagnetic plate 4, having a hole 4a communicated to another hole 1a, is shallowly buried on the side of the magnetic pole surface (b) by performing an insert molding, the plastic magnet on the ferromagnetic plate 4 is thinned off, a protruding edge 1b is integrally provided in a line on the periphery of the magnetic pole surface (b), and the inside of the protruding edge 1b is formed into a recessed surface. Besides, a disc-shaped ferromagnetic plate 2 is insert-molded on the magnetic pole surface (a), it is stuck integrally formed with the permanent magnet 1 by adhesion and the like. On the ferromagnetic plate 2, a ferromagnetic protrusion 2a which is a magnetic interval the inner circumferential surface of the hole 1a is provided, said ferromagnetic protrusion 2a is attached by calking together with the washer-like leg member 5 on which a bent leg piece 5a is integrally provided on the opening surface of the ferromagnetic plate 2, and a female part fitting A is constituted. As a result, the cover is closed completely, and it is not opened carelessly and unintentionally.
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