Self-threading ribbon conveyor

Abstract

A continuous ribbon of moldable material is fed from a plasticizing mill through a stamping section of a molding machine and is returned to the mill as mill stock. The ribbon of moldable material is carried through the stamping section by an endless chain conveyor having prongs spaced therealong. The prongs are pressed into the ribbon as it is drawn from the plasticizing mill. Then, the ribbon is supported by trays as it is drawn along a feed path through the stamping section. The prongs are pulled from the ribbon once the ribbon has been directed by the conveyor back toward the plasticizing mill. At the stamping section, bites are taken from the edge of the ribbon by a die to provide blanks of molding stock to the molding machine. The ribbon is guided by edge guides along a transversely movable supporting tray. The chain conveyor rides in a trough adjacent the tray. By moving the tray and trough away from the stamping die, the mill may be operated continuously even with the mold shut down. As the tray is moved, either to remove the ribbon from the stamping die or to adjust the amount of bite taken from the ribbon, a floating sprocket follows the chain. A variable speed drive to the conveyor chain tracks the mill speed and corrects for ribbon shrinkage and expansion.