| 摘要 |
A ring is formed by first inverting a washer comprising a substantially planar annular member with an outer circumference and a central opening defining an inner circumference, an inner lip extending from one side of the annular member at the inner circumference, an outer lip extending from the same side of the annular member at the outer circumference, and an intermediate section between the first and second lips that reduces in thickness from the inner lip to the outer lip, into a frusto-conical shape; then second inverting the frusto-conical shaped washer into a cylindrical element; and then cold working the cylindrical element by a cold rolling operation so that the annular member assumes an arcuate cross-sectional configuration of substantially constant thickness, whereby to increase a crushing strength of the ring due to the cold rolling and cold working of the cylindrical element and the lips.
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