Apparatus for making corrugated plastic tubing

Claim 1

APPARATUS FOR FORMING CORRUGATED PLASTIC TUBING COMPRISING IN COMBINATION, EXTRUDING MEANS FOR CONTINUOUSLY FORMING PLASTIC TUBING OF ANNULAR CROSS SECTION, MOLDING MEANS IMMEDIATELY ADJACENT SAID EXTRUDING MEANS FOR RECEIVING THE EXTRUDED PLASTIC TUBING AT AN ELEVATED TEMPERATURE AND TRANSVERSELY CORRUGATING THE WALL THEREOF, SAID MOLDING MEANS COMPRISING A PAIR OF ENDLESS CHAIN ASSEMBLIES RESPECTIVELY INCLUDING ENDLESS CHAIN MEANS, SAID CHAIN MEANS BEING ARRANGED WITH RESPECTIVE RUNS THEREOF EXTENDING LONGITUDINALLY AND IN OPPOSED RELATION TO EACH OTHER, A PLURALITY OF DIE MEMBERS SECURED TO EACH OF SAID CHAIN MEANS IN LONGITUDINALLY ADJACENT RELATION TO EACH OTHER FOR MOVEMENT THEREWITH, MEANS FOR GUIDING THE MOVEMENT OF THE OPPOSED RUNS OF SAID CHAIN MEANS TO SUCCESSIVELY BRING RESPECTIVELY OPPOSED DIE MEMBERS THEREOF INTO TIGHT ENGAGEMENT WITH EACH OTHER AND TO DIRECT THE LONGITUDINAL MOVEMENT OF THE ENGAGED DIE MEMBERS, EACH DIE MEMBER HAVING A MOLD CAVITY OF SEMICIRCULAR SECTION FORMED WITH A LONGITUDINALLY EXTENDING UNDULATING MOLD SURFACE WHEREBY THE PAIRED, OPPOSED DIE MEMBERS FORM A MOLD CAVITY OF CIRCULAR SECTION HAVING A TRANSVERSELY CORRUGATED MOLD SURFACE, SAID EXTRUDI G MEANS INCLUDING ORIFICE MEANS FOR DIRECTING THE WALL PORTIONS OF THE LEADING END OF THE EXTRUDED PLASTIC TUBING RADIALLY OUTWARD TOWARD THE MOLD SURFACE OF SAID DIE MEMBERS, SAID ORIFICE MEANS INCLUDING MEANS FOR INTRODUCING AIR UNDER PRESSURE AXIALLY OF SAID PLASTIC TUBING AS SAID TUBING IS ENGAGED BY SAID PAIRS OF DIE MEMBERS WHEREBY THE WALL OF SAID TUBING IS URGED INTO CONFORMATION WITH THE MOLD SURFACE OF SAID DIE MEMBERS TO THEREBY CONTINUOUSLY CORRUGATE THE TUBING AS IT MOVES LONGITUDINALLY WITH THE SUCCESSIVE PAIRS O OPPOSED DIE MEMBERS, AND MEANS FOR RAPIDLY COOLING THE FRESHLY CORRUGATED PLASTIC TUBING DURING ITS ENGAGEMENT WITH SAID PAIRS OF DIE MEMBERS.