| 摘要 |
A method of producing a corrugated annulus is disclosed which has substantially radial folds therein, the method consisting essentially of forming in one continuous straight piece of metal a curved or arcuate head for a reel or the like which method consists in forming a number of radial folds extending from one edge of the strip to the other, the radial folds being of variable depth decreasing from the inner to the outer periphery of the formed annulus.
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