To provide a heat-treating method with which a circumferential length difference between both edge parts of a metallic ring can be reduced.
The circumferential lengths of both edge parts 4a, 4b of the metallic ring 4 formed by rolling after cutting a drum 2 formed by welding a thin plate of maraging steel 1 into a prescribed width, are compared, and the ring is flatly laid at the edge part side 4a having shorter circumferential length. A cylindrical part 12 is inserted into the inner peripheral side of the ring 4 by using a metallic ring holding member 11 and flatly laid on a flange part 13 at the edge part side 4a, and also, a plurality of metallic ring holding members 11 are stacked through the cylindrical parts 12. When the ring 4 is flatly laid on the flange part 13 of the metallic ring holding member 11 at the edge part side 4a, a gap S between the edge part side 4b having longer circumferential length and the flange part 13 of the stacked other metallic holding member 11, is regulated in the range of 1-2 mm.
NAKAJIMA KATSUYUKI
TAKAHASHI TOMOJI
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