PURPOSE: To obtain an electromagnet which can restrain an increase in a magnetic resistance and whose magnetic efficiency is good by a method wherein a yoke and an iron core are formed by bending a magnetic material as one sheet and the iron core is formed by a cold- forging operation in such a way that it is cut and erected forcibly nearly in the center in the axial direction of the yoke.
CONSTITUTION: A yoke 2 and a magnetic core 3 are shaped collectively by a cold-forging operation after a metal sheet (m), as one sheet, composed of a magnetic material has been bent and shaped. That is to say, the metal sheet (m) as one sheet is cut to be nearly L-shaped; an intrusive groove 6 which is parallel to a part to be used as the iron core 3 is formed; the groove 6 is formed in such a way that a magnetic-path width B which is about two-thirds of the total width A of the yoke 2 is left as a base piece 2a for the yoke 2. The part of an armature support piece 2b and the part of the iron core 3 are bent respectively perpendicularly in the same direction (upward) from positions of dotted lines l1, 12 in such a way that they are formed to be at right angles to each other. In addition, a base part 3a at the iron core 3 is cut and erected forcibly by a cold-forging operation and worked and formed so that the iron core 3 is situated in the center in the direction of the total width A of the yoke. Thereby, the minimum apparent cross-sectional area of a magnetic path at the base piece far the yoke is made large, an increase in a magnetic resistance is suppressed and a magnetic efficiency can be improved.
ICHIYA MITSUO
KAJI NORIKIMI
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