| 摘要 |
<p>PROBLEM TO BE SOLVED: To further strengthen joints, by firmly joining highly conductive secondary conductor metal with grooves in a shaft of magnetic material by such means as hot hydrostatic pressure and detonation bonding, and thereby joining a secondary conductor in a groove with adjacent secondary conductor metal in the circumferential direction. SOLUTION: Groove portions 22 where highly conductive secondary conductor metal 23 such as copper is placed on the larger-diameter portion 21a of a magnetic material shaft 21 at equal intervals in the lengthwise direction by hot hydrostatic pressure processing HIP, explosive welding or the like, a portion 23a firmly joined with the end 21b of the larger- diameter portion 21a and having a flush surface, and a short circuit portion 23b are formed on the magnetic material shaft 21 of a rotor. The outer surface of the larger-diameter portion 21a between a groove portion 22 and an adjacent groove portion 22 are completely covered with secondary conductor metal 23, not more than 1 mm in thickness, and the secondary conductor metal 23 is continuously joined in the circumferential direction. Strength against centrifugal force due to high-speed rotation is further enhanced because of this constitution. Since the thickness of the secondary conductor metal 23 covering the short circuit portion 23b is as small as not more than 1 mm, degradation in magnetic characteristic due to the secondary conductor metal 23 can be prevented by the presence of the short circuit portion 23b.</p> |
