| 摘要 |
PROBLEM TO BE SOLVED: To easily and inexpensively work through holes and to prevent the easy occurrence of chipping by setting a ratio between the diameter of the pierced through hole and the thickness of a sintered magnet body to be within a specified value range. SOLUTION: A permanent magnet 2 is the rare earth sintered magnet of Nd-Fe-B and a size is 56 mm×22 mm×9 mm. Through holes 5 whose diameters (d) are 6 mm are uniformly formed in right and left at an almost center part by piercing work. The ratio d/t of the thickness (t) of a sintered magnet body to the diameter (d) of the pierced through hole is about 0.7. Since the thickness of the arcuate sintered magnet body is limited on manufacture, it is about 2 to 25 mm. When the through holes are aimed to fasten/fix the magnets, fastening strength is sufficient for bolts inserted through the holes whose diameters are 3 to 10 mm. When the through hole is to be made in the rare earth sintered magnet by machining, d/t is set to be in the range of 0.1 to 5 from a factor in terms of a shape.
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