| 摘要 |
Apparatus for molding plastic articles having an undercut, rib, thread, or the like deformation comprises a core divided longitudinally into sections having molding ends that are radially shiftable to and from an expanded article-molding position and a contracted article-release position. A center pin holds the sections expanded. The core may be shifted axially resulting in the center pin being withdrawn from support of the molding ends of the sections. This causes a cam ring that encircles the sections to urge the sections radially inwardly by the engagement of cam-follower lugs on the sections to collapse positively the sections without interference from the pin. |
