| 摘要 |
There is disclosed a planar sheet having at least one longitudinal corrugation for substantially the entire width of the panel. On at least one end portion of the sheet the corrugation terminates into a plurality of smaller gathered corrugations resulting in closed ends. Apparatus is also disclosed for producing the aforementioned smaller gathered corrugations including an anvil having appropriate cavities therein and a punch system for upsetting a corrugated panel to produce said mini-corrugation. |
