Systems and methods for deforming an outer wall of pipe

1. A method of deforming an outer wall of polymer pipe, the method comprising:

forming dual-wall pipe having a smooth wall and a corrugated wall;

extruding an outer wall of pipe onto the corrugated wall of the dual-wall pipe;

puncturing the outer wall of pipe with a vacuum punch; and

drawing a vacuum between the corrugated wall and the outer wall via the vacuum punch;

wherein the vacuum between the corrugated wall and the outer wall causes the outer wall to deform in a direction towards the corrugated wall.

2. The method of claim 1 , wherein forming dual-wall pipe comprises co-extruding the smooth wall and corrugated wall into translating molds of a corrugator.

3. The method of claim 1 , wherein extruding the outer wall of pipe comprises extruding the outer wall of pipe from a cross-head die disposed downstream from a corrugator.

4. The method of claim 1 , wherein the step of puncturing the outer wall of pipe is performed while the outer wall is hot enough to deform when hot air is evacuated from between the corrugated wall and the outer wall.

5. The method of claim 1 , wherein the step of drawing a vacuum is performed until the outer wall has contacted the corrugated wall in an area surrounding around the hollow needle.

6. The method of claim 1 , wherein the dual-wall pipe comprises an in-line coupling preform made from the smooth wall and the corrugated wall, and

wherein puncturing the outer wall of pipe comprises inserting a hollow needle into a closed cavity defined between the outer wall and the corrugated wall of the in-line coupling preform.

7. The method of claim 6 , wherein the in-line coupling preform comprises an in-line bell and an in-line spigot, and

wherein the closed cavity is further defined by a portion of the corrugated wall extending between the in-line bell and the in-line spigot.

8. The method of claim 1 , wherein the dual-wall pipe comprises an in-line coupling preform comprising an in-line bell and an in-line spigot,

wherein the in-line coupling preform further comprises a channel extending from the in-line bell to the in-line spigot; and

wherein puncturing the outer wall of pipe comprises using the vacuum punch to puncture an end of the channel proximate to the in-line bell.

9. The method of claim 8 , wherein the channel protrudes radially-inward into the corrugated wall and extends axially from the in-line bell to the in-line spigot; and wherein the in-line bell is disposed radially-outward from the in-line spigot, such that a tip of the vacuum punch is disposed radially-outward from the in-line spigot when the vacuum punch is positioned at the end of the channel proximate to the in-line bell.

10. A method of deforming an outer wall of polymer pipe, the method comprising:

forming dual-wall pipe having a smooth wall and a corrugated wall;

extruding an outer wall of pipe onto the corrugated wall of the dual-wall pipe;

puncturing the outer wall of pipe with a vacuum punch; and

drawing a vacuum between the corrugated wall and the outer wall via the vacuum punch, continuously until the outer wall has contacted the corrugated wall in an area surrounding the hollow needle;

wherein the vacuum between the corrugated wall and the outer wall causes the outer wall to deform in a direction towards the corrugated wall.

11. The method of claim 10 , wherein forming dual-wall pipe comprises co-extruding the smooth wall and corrugated wall into translating molds of a corrugator.

12. The method of claim 10 , wherein extruding the outer wall of pipe comprises extruding the outer wall of pipe from a cross-head die disposed downstream from a corrugator.

13. The method of claim 10 , wherein the step of puncturing the outer wall of pipe is performed while the outer wall is hot enough to deform when hot air is evacuated from between the corrugated wall and the outer wall.

14. The method of claim 10 , wherein the dual-wall pipe comprises an in-line coupling preform made from the smooth wall and the corrugated wall, and

wherein puncturing the outer wall of pipe comprises inserting a hollow needle into a closed cavity defined between the outer wall and the corrugated wall of the in-line coupling preform.

15. The method of claim 14 , wherein the in-line coupling preform comprises an in-line bell and an in-line spigot, and

wherein the closed cavity is further defined by a portion of the corrugated wall extending between the in-line bell and the in-line spigot.

16. The method of claim 10 , wherein the dual-wall pipe comprises an in-line coupling preform comprising an in-line bell and an in-line spigot, the in-line bell and in-line spigot each being made from the smooth wall and the corrugated wall;

wherein the in-line coupling preform further comprises a channel formed in the corrugated wall, the channel extending from the in-line bell to the in-line spigot; and

wherein puncturing the outer wall of pipe comprises using the vacuum punch to puncture an end of the channel proximate to the in-line bell.

17. The method of claim 16 , wherein the channel protrudes radially-inward into the corrugated wall and extends axially from the in-line bell to the in-line spigot; and wherein the in-line bell is disposed radially-outward from the in-line spigot, such that a tip of the vacuum punch is disposed radially-outward from the in-line spigot when the vacuum punch is positioned at the end of the channel proximate to the in-line bell.

18. A method of deforming an outer wall of polymer pipe, the method comprising:

forming dual-wall pipe having a smooth wall and a corrugated wall, including an in-line coupling preform comprising an in-line bell and an in-line spigot, the in-line bell and in-line spigot each being made from the smooth wall and the corrugated wall, the in-line coupling comprising a channel formed in the corrugated wall, the channel extending from the in-line bell to the in-line spigot;

extruding an outer wall of pipe onto the corrugated wall of the dual-wall pipe;

puncturing the outer wall of pipe with a vacuum punch at an end of the channel proximate to the in-line bell; and

drawing a vacuum between the corrugated wall and the outer wall via the vacuum punch;

wherein the vacuum between the corrugated wall and the outer wall causes the outer wall to deform in a direction towards the corrugated wall.

19. The method of claim 18 , wherein forming dual-wall pipe comprises co-extruding the smooth wall and corrugated wall into translating molds of a corrugator.

20. The method of claim 18 , wherein extruding the outer wall of pipe comprises extruding the outer wall of pipe from a cross-head die disposed downstream from a corrugator.

21. The method of claim 18 , wherein the step of puncturing the outer wall of pipe is performed while the outer wall is hot enough to deform when hot air is evacuated from between the corrugated wall and the outer wall.

22. The method of claim 18 , wherein the step of drawing a vacuum is performed continuously until the outer wall has contacted the corrugated wall in an area surrounding the hollow needle.

23. The method of claim 18 , wherein the dual-wall pipe comprises an in-line coupling preform made from the smooth wall and the corrugated wall, and

wherein puncturing the outer wall of pipe comprises inserting a hollow needle into a closed cavity defined between the outer wall and the corrugated wall of the in-line coupling preform.

24. The method of claim 23 , wherein the in-line coupling preform comprises an in-line bell and an in-line spigot, and

wherein the closed cavity is further defined by a portion of the corrugated wall extending between the in-line bell and the in-line spigot.