Patent ID: 8579624

Claim:
A system for manufacturing multi-wall corrugated polymer pipe, the system comprising: an extruder configured to co-extrude concentric annular tubes; a corrugator configured to form the concentric annular tubes into a dual-wall pipe having a smooth wall and a corrugated wall, the corrugated wall including bell and spigot portions; a cross-head die configured to extrude an outer wall of pipe onto the corrugated wall of the dual-wall pipe; a vacuum punch configured to penetrate the outer wall of pipe and draw a vacuum between the corrugated wall and the outer wall, such that the outer wall of pipe deforms inward toward the corrugated wall of pipe between the bell and spigot portions of the corrugated wall; a press roller configured to press the outer wall against the corrugated wall, wherein the press roller is positioned downstream the vacuum punch; and a cutter configured to cut the pipe into sections where the vacuum punch deformed the outer wall between the bell and spigot portions of the corrugated wall.