Abstract: A system is disclosed for manufacturing multi-wall corrugated polymer pipe. The system includes 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; 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 bell and spigot portions of the corrugated wall; 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. A method of manufacturing multi-wall corrugated polymer pipe is also disclosed.

Abstract: A mold is provided for forming a continuously-extruded parison into a corrugated pipe. The mold includes a mold housing having a plurality of bores, a mold cavity having a plurality of annular corrugations, and a plurality of punches. Each punch is disposed in one of the bores and aligned with one of the annular corrugations of the mold cavity. Each punch is also configured to form an aperture in a corrugation of a corrugated pipe in the mold. A continuous extrusion blow molding system and a method are also provided for forming a hollow plastic product and punching a continuously-extruded, blow molded product before it is released from a mold.

Abstract: An extrusion die configured to have an interior chamber sealed from the atmosphere is disclosed. The extrusion die includes an extrusion die head disposed at a downstream end of the interior chamber; and a vacuum seal disposed at an upstream end of the interior chamber; wherein the vacuum seal is configured to selectively form a seal between the extrusion die and a product disposed in the interior chamber. The vacuum seal includes an annular sealing surface disposed at an inner diameter of the vacuum seal; a hollow, interior chamber; and a plurality of bellows disposed between the annular sealing surface and the extrusion die; wherein the vacuum seal is configured to selectively form a seal between the extrusion die and a product disposed in the interior chamber. A method of selectively sealing an end of an extrusion die is also disclosed.

Abstract: A pipe extrusion die may be provided having an inner flow passageway having a first cross-sectional area, and an outer flow passageway having a second cross-sectional area, both being in communication with an inlet flow passageway. A ratio adjusting tube may be movably disposed in blocking engagement between the inlet flow passageway and the inner flow passageway. The ratio adjusting tube and the outer flow passageway both may be substantially concentric with the inner flow passageway. Material may be distributed from the inlet flow passageway to the inner and outer flow passageways. The method and apparatus may allow for the manual and automatic control of the proportion of material distributed between the inner and outer flow passageways by adjusting the position of the ratio adjusting tube in relation to a passageway between the inlet flow passageway and the inner flow passageway, based on various operating parameters.

Abstract: An in-line coupling pipe is provided having a plurality of first corrugations with a male portion at one end of the pipe and a female portion at the other end. The diameter at the crest of the first corrugation being a first distance. The male portion having a second corrugation with the diameter at the crest of the second corrugation being a second distance. The male portion of having a third corrugation intermediate the first corrugation and the second corrugation, with the diameter at the crest of the third corrugation being a third distance. The male portion having a fourth corrugation intermediate the first corrugation and the third corrugation, with the diameter at the crest of the fourth corrugation being a fourth distance, with the first distance being greater than the second or third or fourth distances, the second distance being greater than the third distance, and the fourth distance being greater than second or third distances. The second corrugation has a recess formed therein.

Abstract: A system is disclosed for manufacturing multi-wall corrugated polymer pipe. The system includes 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; 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 bell and spigot portions of the corrugated wall; 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. A method of manufacturing multi-wall corrugated polymer pipe is also disclosed.

Abstract: A mold is provided for forming a continuously-extruded parison into a corrugated pipe. The mold includes a mold housing having a plurality of bores, a mold cavity having a plurality of annular corrugations, and a plurality of punches. Each punch is disposed in one of the bores and aligned with one of the annular corrugations of the mold cavity. Each punch is also configured to form an aperture in a corrugation of a corrugated pipe in the mold. A continuous extrusion blow molding system and a method are also provided for forming a hollow plastic product and punching a continuously-extruded, blow molded product before it is released from a mold.

Abstract: An extrusion die configured to have an interior chamber sealed from the atmosphere is disclosed. The extrusion die includes an extrusion die head disposed at a downstream end of the interior chamber; and a vacuum seal disposed at an upstream end of the interior chamber; wherein the vacuum seal is configured to selectively form a seal between the extrusion die and a product disposed in the interior chamber. The vacuum seal includes an annular sealing surface disposed at an inner diameter of the vacuum seal; a hollow, interior chamber; and a plurality of bellows disposed between the annular sealing surface and the extrusion die; wherein the vacuum seal is configured to selectively form a seal between the extrusion die and a product disposed in the interior chamber. A method of selectively sealing an end of an extrusion die is also disclosed.

Abstract: A pipe extrusion die may be provided having an inner flow passageway having a first cross-sectional area, and an outer flow passageway having a second cross-sectional area, both being in communication with an inlet flow passageway. A ratio adjusting tube may be movably disposed in blocking engagement between the inlet flow passageway and the inner flow passageway. The ratio adjusting tube and the outer flow passageway both may be substantially concentric with the inner flow passageway. Material may be distributed from the inlet flow passageway to the inner and outer flow passageways. The method and apparatus may allow for the manual and automatic control of the proportion of material distributed between the inner and outer flow passageways by adjusting the position of the ratio adjusting tube in relation to a passageway between the inlet flow passageway and the inner flow passageway, based on various operating parameters.