| 摘要 |
Apparatus for cold-forming a thermoplastic sheet to provide a circular container part such as a lid or dish comprising opposing concentric die members for engaging a sheet of thermoplastic material, the sheet being drawn around the circular edge of one of the die members to provide a concentric central portion and a concentric annular depending skirt having a proximal edge adjacent the central portion, an intermediate portion, and a distal free edge, providing an annular void in the die members adjacent the skirt. Apparatus is provided for moving the free edge toward the proximal edge while holding the proximal edge to buckle the intermediate portion into the void. The void has a tapered surface inclining radially outwardly and axially toward the proximal edge to hold the free edge radially inwardly, thereby to permit the intermediate portion to buckle outwardly into the void.
|
