| 摘要 |
PURPOSE:To facilitate the formation of lug portion without causing any trouble in the formation of V-groove by preliminarily forming a lug portion projecting radially outwards at both end edges of the circumferential wall of a cup-shaped element before the formation of corrugated shape. CONSTITUTION:A cup-shaped element 1 is molded of a sheet metal by press machining. The cup-shaped element 1 has a shape in which a large-diameter circumferential wall 4 is connected through a stepped portion 3 to a small-diameter cup portion 2. Lug portions 6' and 7' are preliminarily formed at both end edges of the circumferential wall of the cup-shaped element 1, and the element is treated by a corrugating roller 20 in such a way that a corrugated form having alternately shaped plural peaks 8 and troughs 9 is formed on the outside of the circumferential wall 4. Then, the corrugated circumferential wall 4 is compressed toward axially, and lastly the cup-shaped element is subjected to finishing molding. |
