| 摘要 |
PROBLEM TO BE SOLVED: To provide a core which has excellent magnetic characteristics, improved core precision and sufficient coupling strengths between steel plates. SOLUTION: Steel plates in which necessary holes are formed are piled in layers while they are turned successively in a certain turning direction, by a predetermined angle to form a hole 21 inclined by an angleδfrom an axial direction. The weldable parts which are parts of the steel plates shifted in step shapes are welded successively by spot welding with a laser beam, which is applied to the parts to be welded from the above with inclination from the layer-building direction of the core. Further, if the incident angle of the laser beam is denoted byθ, the thickness of the steel plate is denoted by (t) and the spot diameter of the laser beam is denoted by (d), the following relation is satisfied: d>(2t/cos<δ)×cosθ. Then, adjacent three or more steel plates are mutually welded.
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