Method and apparatus for manufacturing foldable conduit

Abstract

A sleeve of plastic material from an extruder is molded by a blow molding apparatus into a tubular structure which includes two top walls longitudinally connected at base ends and apex ends. A splitting apparatus splits the longitudinally connected base ends apart to form two top walls. The top walls are oriented with their base ends upward. An extruder extrudes a flow of softened plastic which is divided by a manifold into four flows. Four applicators connected with the manifold apply beads of softened plastic along each top wall base end. A ribbed roller presses flexible strips against the plastic beads on each of the top walls. The flexible strips are fed from rolls of finite length mounted on a stand. The stand holds operating rolls and back up rolls. A splicing apparatus splices the trailing end of each operating roll with a leading end of the corresponding back up roll. An accumulator accumulates a reserve of the flexible strip between splices and feeds out the reserve during a splice such that the flexible strip is fed continuously to the ribbed roller. A perforator apparatus perforates the flexible strip and a vent trimmer perforates the top wall. A puller clamps the conduit in a folded configuration to pull it through the splitter, and ribbed roller. The folded conduit is cut to length and wound on reels.