US20100089074A1

US20100089074A1 - Apparatus and Method for Cooling an Outer Wall of Pipe

Info

Publication number: US20100089074A1
Application number: US12/250,960
Authority: US
Inventors: Gerald S. Sutton; David J. Kelley
Original assignee: Individual
Current assignee: Advanced Drainage Systems Inc
Priority date: 2008-10-14
Filing date: 2008-10-14
Publication date: 2010-04-15
Also published as: CA2681901A1; CA2681901C

Abstract

A method of cooling an outer wall of polymer pipe is provided. The method includes extruding a layer of polymer onto a pipe to form an outer wall of pipe; conveying the pipe including the outer wall of pipe through an inner aperture of an annular air-cooler having an annular air manifold; and blowing pressurized air, at a temperature lower than a temperature of the outer wall of pipe, through the annular air manifold such that it contacts the outer wall of pipe and cools the outer wall of pipe at a rate that is a function of a pressure of the pressurized air and a difference between the temperature of the pressurized air and the temperature of the outer wall of pipe. An apparatus for cooling an outer wall of polymer pipe is also provided.

Description

TECHNICAL FIELD

The present disclosure relates to manufacturing three-wall corrugated pipe walls, and more particularly, to an apparatus and method for cooling an outer wall of pipe after an outer layer of polymer is extruded onto a dual-wall corrugated pipe to form the outer wall of the three-wall pipe.

BACKGROUND

Drainage pipe has long been used for transporting water in various agricultural, residential, civil engineering, and other construction applications. For example, drainage pipe has been used to create storm sewer systems configured to collect and dispose of water “run-off”. Traditionally, drainage pipe was made from clay or concrete, which caused the pipe to be heavy, expensive, and brittle. In order to improve the ease-of-installation, cost-effectiveness, and durability of drainage pipes, they are now sometimes manufactured from alternative materials, including various polymers and polymer blends.
One method of manufacturing polymer pipe involves forming a polymer pipe and then extruding an outer layer of polymer onto the outside of the polymer pipe. As a result, the outer layer of polymer may now constitute an outer pipe wall, which is fused to the exterior surface of the polymer pipe. This outer layer of polymer is generally extruded at a temperature sufficiently high to allow it to properly bond with the exterior surface of the polymer pipe. Specifically, the extruded outer layer of polymer is extruded at a temperature hot enough to at least partially melt the exterior surface of the polymer pipe, such that polymer chains of the exterior surface and the extruded outer wall intersperse and then cool together. This results in the exterior surface and the extruded outer wall being integrally fused or bonded together wherever they contact each other.
Because the outer layer of polymer is extruded at a high temperature, it can sometimes exhibit behavior that is detrimental to forming an outer wall with particular aesthetic and/or structural characteristics. For example, the hot outer layer of polymer may droop between adjacent portions of the exterior surface of the polymer pipe. Furthermore, the hot outer layer may be undesirably deformed by processes performed downstream from its extrusion. The hot outer layer may also contribute to hot gas being trapped in spaces formed between the extruded outer layer and the exterior surface of the polymer pipe.
Accordingly, there is a need for an apparatus and method for cooling an outer wall of pipe.

SUMMARY

It is an object of the present invention to provide such an apparatus and method for cooling an outer wall of pipe.
One exemplary embodiment of the present disclosure provides a method of cooling an outer wall of polymer pipe. The method includes extruding a layer of polymer onto a pipe to form an outer wall of pipe; conveying the pipe including the outer wall of pipe through an inner aperture of an annular air-cooler having an annular air manifold; and blowing pressurized air, at a temperature lower than a temperature of the outer wall of pipe, through the annular air manifold such that it contacts the outer wall of pipe and cools the outer wall of pipe at a rate that is a function of a pressure of the pressurized air and a difference between the temperature of the pressurized air and the temperature of the outer wall of pipe.
Another exemplary embodiment of the present disclosure provides a method of cooling an outer wall of polymer pipe. The method includes forming dual-wall pipe having a smooth wall and a corrugated wall, the corrugated wall having a plurality of alternating corrugation crests and corrugation valleys; extruding an outer wall of pipe onto the corrugated wall of the dual-wall pipe so as to form three-wall pipe, the outer wall of pipe being fused to every corrugation crest of the corrugated wall, the outer wall of pipe further having a plurality of concave portions, each concave portion extending across a corrugation valley between two adjacent corrugation crests; and conveying the three-wall pipe through an annular air-cooler having an annular air passageway disposed at an inner diameter of the annular air-cooler; wherein the annular air-cooler is configured to eject pressurized cooling air from the annular air passageway against the outer wall of pipe so as to cool the outer wall of pipe and control an amount of concavity in each of the concave portions.
Yet another exemplary embodiment of the present disclosure provides an apparatus for cooling an outer wall of polymer pipe. The apparatus includes an annular air manifold having an outer diameter and an inner diameter, the inner diameter defining an inner aperture; an air inlet disposed in fluid communication with the annular air manifold; and an annular passageway disposed in fluid communication with the annular air manifold at the inner diameter; wherein the apparatus is configured to convey air, at a temperature lower than a temperature of the outer wall of pipe, through the air inlet, around the annular air manifold, and through the annular passageway, so as to cool an outer wall of polymer pipe when the polymer pipe is translated through the inner aperture.
In this respect, before explaining at least one embodiment of the disclosure in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
The accompanying drawings illustrate certain exemplary embodiments of the disclosure, and together with the description, serve to explain the principles of the invention.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the present invention. It is important, therefore, to recognize that the claims should be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary embodiment of a air-cooler for cooling an outer wall of pipe;

FIG. 2 is a partial, cross-sectional view of the exemplary air-cooler depicted in FIG. 1; and

FIG. 3 is a cross-sectional view of a system and method for cooling an outer layer of pipe using the exemplary air-cooler illustrated in FIGS. 1 and 2.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Reference will now be made in detail to the exemplary embodiments described above and illustrated in the accompanying drawings.
During the manufacture of multi-wall polymer pipe, concentric tubes of polymer may be continuously extruded from one or more extrusion dies. A corrugator may be used to form corrugations into one or more of the layers of polymer as they continuously translate away from the extrusion dies. In one embodiment, a corrugator may be used to form dual-wall pipe having a smooth inner wall and a corrugated wall. The corrugated wall may have a plurality of alternating corrugation crests and corrugation valleys, with the corrugation valleys being fused to the smooth inner wall. In order to improve the performance of such a pipe, it may be desirable to extrude an additional layer of polymer onto the pipe. For example, a cross-head die may be used to extrude an outer layer of polymer onto the exterior surface of the corrugated wall, thereby forming three-wall, corrugated polymer pipe. The outer layer of polymer may be extruded at a temperature high enough to bond or fuse the outer layer of polymer to corrugation crests of the corrugated wall. In some cases, it may be desirable to cool an outer layer of polymer pipe after the outer layer is extruded onto the exterior surface of a dual-wall corrugated polymer pipe.
FIG. 1 illustrates an exemplary air-cooler 10 for cooling an outer layer of pipe. In one embodiment, air-cooler 10 may be used for cooling an outer layer of pipe after the outer layer is extruded onto the pipe but before the pipe enters a spray tank and/or perforator. For instance, air-cooler 10 may be mounted downstream from a pipe corrugator, a cross-head die, a vacuum punch, or any other multi-wall pipe manufacturing apparatus. Air-cooler 10 may be mounted upstream from a press-roller, a spray tank, a perforator, or any other pipe post-processing apparatus. In one embodiment, air-cooler 10 may be used without a spray tank in the event that air-cooler 10 is sufficient for desirably cooling the outer layer of pipe. Air-cooler 10 may include a plurality of brackets by which it may either support, or be mounted to, an adjacent pipe manufacturing apparatus. For example, air-cooler 10 may include a plurality of bearings 13, which may support an adjacent apparatus (not shown) configured to press an outer layer of pipe against an inner layer of pipe.
Air-cooler 10 may include an annular air manifold 12, which has an outer diameter 14 and an inner diameter 16. Air-cooler 10 may have an interior aperture 15 defined by inner diameter 16, through which a multi-layer pipe may be conveyed. Specifically, as shown in FIG. 1, a multi-wall pipe may be configured to continuously translate in a direction “D” through interior aperture 15 of air-cooler 10.
As illustrated in FIG. 1, air-cooler 10 may include one or more air inlets 17 disposed in fluid communication with air manifold 12. As shown in the embodiment of FIG. 1, air inlets 17 may be in fluid communication with air manifold 12 at outer diameter 14. Air inlets 17 may also be disposed in fluid communication with a pressurized air supply (not shown). For example, air inlets 17 may connect an interior of air manifold 12 with a hose or duct connected to an air pump (not shown). Thus, air inlets 17 may be configured to convey pressurized air into a hollow interior of air manifold 12. The embodiment of FIG. 1 depicts air-cooler 10 having two air inlets 17, each being disposed 180° from the other around air manifold 12. However, it will be appreciated that air-cooler 10 may include any number of air inlets 17, it being understood that additional air inlets may reduce turbulence in air manifold 12 and reduce the distance that air must travel around air manifold 12 before exiting towards interior aperture 15.
In order to release pressurized air from air manifold 12 into interior aperture 15, air-cooler 10 may further include a first ring 18 and a second ring 20. First ring 18 and second ring 20 may be disposed along inner diameter 16 of air manifold 12. Moreover, first ring 18 and second ring 20 may be formed substantially adjacent to each other and configured to form an annular opening between air manifold 12 and interior aperture 15. Thus, first ring 18 and second ring 20 may form an annular passageway through which pressurized air may exit air-cooler 10 around its entire inner diameter 16.
FIG. 2 illustrates a cross-section of one portion of the exemplary air-cooler 10 of FIG. 1. As shown in FIG. 2, air manifold 12 may include a hollow interior duct 11. Interior duct 11 may be an annular shaped conduit that runs around the entire circumference of air manifold 12. FIG. 2 illustrates an air inlet 17 in communication with a portion of interior duct 11 spaced radially apart from that of the cross-section. Nevertheless, air inlet 17 may provide a supply of air around the entire circumference of interior duct 11. As described above, first ring 18 and second ring 20 may be provided in communication with interior duct 11 along inner diameter 16 of air manifold 12. Moreover, first ring 18 and second ring 20 may be cooperatively spaced apart so as to form an annular passageway 22 from interior duct 11 to interior aperture 15.
Thus, air may travel from a pressurized supply into interior duct 11 via air inlet 17. Moreover, air may travel from interior duct 11 into interior aperture 15 via annular passageway 22. As depicted in FIG. 2, first ring 18 and second ring 20 may be shaped so as to form annular passageway 22 as a slit angled relative to a central axis “y” of the air-cooler 10. Specifically, at each point around the circumference of air-cooler 10, annular passageway 22 may be oriented along an axis “α,” which is disposed at an angle “Θ” from central axis “y.” In one embodiment, angle “Θ” may be between 5° and 40°. In another embodiment, angle “Θ” may be between 10° and 20°. In yet another embodiment, angle “Θ” may be approximately 15°. First ring 18 and second ring 20 may be provided with any suitable type of mechanism configured to selectively adjust angle “Θ”. Moreover, first ring 18 and second ring 20 may be provided with any suitable type of mechanism configured to translate first ring 18 and second ring 20 relative to each other, so as to adjust a width of annular passageway 22.
Interior duct 11 may be provided with any type of interior liner (not shown) disposed in fluid communication with air inlet 17 and annular passageway 22. Moreover, interior duct 11 may be provided with any type of heating apparatus, cooling apparatus, chemical ejecting apparatus, liquid ejecting apparatus, vapor ejecting apparatus, and/or particle ejecting apparatus. Thus, interior duct 11 may be configured to convey any type of treated air, fluid, or other desired material from interior duct 11, through annular passageway 22, and into interior aperture 15, so as to selectively treat an exterior surface of a pipe conveyed through interior aperture 15.
As illustrated in FIG. 3, the exemplary air-cooler 10 may be disposed in a pipe manufacturing system downstream from a cross-head die 110. Specifically, in a multi-wall pipe manufacturing process, a cross-head die 110 may be used to extrude an outer layer of polymer 126 onto a dual-wall pipe 120. The dual-wall pipe 120 may include a smooth inner wall 122 defining an internal bore 121, and a corrugated wall 123. Such a dual-wall pipe 120 may have been formed by co-extruding two layers of molten polymer into a corrugator. As shown in FIG. 3, dual-wall pipe 120 may be conveyed into cross-head die 110, which may include an internal diameter 111 defining an internal chamber 113. In one embodiment, a vacuum pump 128 may be disposed in fluid communication with internal chamber 113. Thus, as the outer layer of polymer 126 is extruded from a first end 112 of cross-head die 110, a vacuum may be drawn on internal chamber 113, thereby forcing the outer layer of polymer 126 against corrugation crests of corrugated wall 123 of dual-wall pipe 120. This process may result in a three-wall pipe 125, having an outer wall 124 fused to corrugated wall 123 of dual-wall pipe 120.
In one embodiment, the outer layer of polymer 126 may be extruded at a temperature sufficiently high to allow the outer layer to properly bond with corrugation crests of corrugated wall 123. Specifically, the outer layer of polymer 126 may be hot enough to at least partially melt the corrugation crests of corrugated wall 123, such that polymer chains of corrugated wall 123 and outer wall 124 intersperse and then cool together. This may result in corrugated wall 123 and outer wall 124 being integrally fused or bonded together at each corrugation crest of corrugated wall 123.
Because the outer layer of polymer 126 may be extruded at a high temperature, it may exhibit behavior that is detrimental to forming an outer wall 124 with particular aesthetic and/or structural characteristics. For example, the hot outer layer of polymer may droop between adjacent corrugation crests of corrugated wall 123. Furthermore, the hot outer layer may be undesirably deformed by processes performed downstream from its extrusion. The hot outer layer may also contribute to hot gas being trapped in spaces formed between corrugated wall 123 and outer wall 124.
Thus, air-cooler 10 may be positioned in a downstream direction “D” from cross-head die 110, such that air-cooler 10 is configured to cool outer wall 124 after it is extruded from cross-head die 110. In one embodiment, air-cooler 10 may be disposed downstream from a corrugator (not shown), downstream from a cross-head die 110, and downstream from a vacuum punch apparatus (not shown), but upstream from a press-rolling apparatus (not shown), upstream from a spray tank apparatus (not shown), and upstream from an outer wall perforator (not shown). Thus, a vacuum punch apparatus may be used to punch a plurality of apertures into certain portions of outer wall 124, as desired, before three-wall pipe 125 is conveyed through air-cooler 10. Moreover, the press-rolling apparatus may be used to press outer wall 124 against corrugated wall 123, and the outer wall perforator may be used to perforate outer wall 124, after three-wall pipe 125 is conveyed through air-cooler 10. As shown in FIG. 3, air-cooler 10 may be disposed in communication with an air pump 130, for supplying pressurized air to air manifold 12 of air-cooler 10. Air-cooler 10 may be oriented relative to cross-head die 110 such that the angled slit formed by annular passageway 22 directs air in the axially-downstream direction “D” and radially-inward towards a pipe translating through air-cooler 10. In another embodiment, the pressure surrounding a pipe, having an outer layer extruded thereon, translating through cross-head die 110 is maintained substantially constant as the pipe is translated from cross-head die 110 through air-cooler 10. In particular, the pressure surrounding the pipe may be less than atmospheric pressure when the pipe exits cross-head die 110 and enters air-cooler 10.
Air-cooler 10 may be configured to cool an outer surface of outer wall 124 but not a middle or an inner surface of outer wall 124. In one embodiment, the outer surface of outer wall 124 may be cooled just enough to create a thin layer of solidified material on its outer surface. Thus, an outer wall perforating apparatus positioned downstream from air-cooler 10 may be able to create clean perforations in outer wall 124 without causing undesirable deformation of outer wall 124. Moreover, because air-cooler 10 may cool an outer surface of outer wall 124, a spray tank apparatus positioned downstream from air-cooler 10 may be mitigated from causing undesirable deformation and texturing of the outer surface of outer wall 124. By avoiding spray tank texturing, outer wall 124 may be more aesthetically pleasing and it may provide more tensile strength than an outer wall impacted by water in a spray tank before a air-cooling process. However, as described above, air-cooler 10 may be used without a spray tank in the event that air-cooler 10 is sufficient for desirably cooling the outer layer of pipe, in which case outer layer deformation and texturing may be avoided altogether. Air-cooler 10 may also be configured to avoid cooling outer wall 124 so much that air trapped between corrugated wall 123 and outer wall 124 will cool down, reduce in volume, and create a deformation-inducing vacuum in spaces between corrugation crests of corrugated wall 123 and outer wall 124.
In one embodiment, cross-head die 110 may extrude the outer layer of polymer 126 such that it creates slightly concave portions in outer wall 124 between adjacent corrugation crests of corrugated wall 123. Specifically, outer wall 124 may have a concave portion extending across each corrugation valley and between adjacent corrugation crests of corrugated wall 123. Air-cooler 10 may be used to cool outer wall 124 at a rate that facilitates the formation of a desirable amount of concavity in concave portions in outer wall 124. For example, air-cooler 10 may cool outer wall 124 quickly enough to mitigate the effect that gravity would otherwise have on the still molten outer wall 124 after it is extruded from cross-head die 110. This may be performed to prevent gravity from making concave portions on the top of the pipe more concave, and making concave portions on the bottom of the pipe less concave. Thus, air-cooler 10 may cool outer wall 124 at a rate that promotes uniformity of the profile of outer wall 124 around its entire circumference and along its length.
Air-cooler 10 may be used to cool outerwall 124 at a rate that is a function of the temperature and pressure of air conveyed through air-cooler 10. The rate of cooling may also be a function of the difference between the temperature of air conveyed through the air-cooler and the temperature of the outer wall 124. In one embodiment, the pressurized air is at the temperature of ambient air. However, it will be appreciated that the pressurized air may be heated or cooled to any temperature. The air may be pressurized such that air in air manifold 12 has a pressure between approximately 0.5 PSI and 30.0 PSI. Moreover, the air may be pressurized so as to provide a pressure against the pipe of approximately 3 cfm/inch to 8 cfm/inch on the pipe surface. Of course, it will be appreciated that any desired air flow rate is contemplated for use in cooling or otherwise treating the pipe. Moreover, both the temperature and flow rate of the air may be readily adjusted manually, or automatically in real-time, as desired.
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Claims

1-9. (canceled)

10. An apparatus for cooling an outer wall of polymer pipe, the apparatus comprising:

an annular air manifold having an outer diameter and an inner diameter, the inner diameter defining an inner aperture and a lane of the apparatus, a centerpoint of the inner aperture intersecting a pipe-conveying direction;

an air inlet disposed in fluid communication with the annular air manifold; and

an annular passageway defined by a first ring and a second ring, and disposed in fluid communication with the annular air manifold at the inner diameter;

wherein the first ring has a first frusto-conical face, the second ring has a second frusto-conical face, and the first and second frusto-conical faces are parallel to each other and disposed at an angle towards the pipe-conveying direction; and

wherein the apparatus is configured to convey air, at a temperature lower than a temperature of the outer wall of pipe, through the air inlet, around the annular air manifold, and through the annular passageway, so as to cool an outer wall of polymer pipe when the polymer pipe is translated through the inner aperture in the pipe conveying direction.

11. The apparatus of claim 10, wherein the air inlet is disposed in fluid communication with the annular air manifold at the outer diameter.

12. The apparatus of claim 10, wherein the air inlet is further disposed in fluid communication with an air supply.

13. The apparatus of claim 12, wherein the air supply is a pump.

14-15. (canceled)

16. The apparatus of claim 10, wherein the annular passageway is disposed at an angle between 5 and 40 degrees from the plane of the apparatus.

17. The apparatus of claim 10, wherein the annular passageway is disposed at an angle of approximately 15 degrees from the plane of the apparatus.

18. The apparatus of claim 10, wherein the apparatus is oriented relative to an outer pipe wall manufacturing apparatus such that the annular passageway is configured to direct air in a downstream direction of a pipe translated through the inner aperture.

19. The apparatus of claim 10, wherein the apparatus comprises a plurality of bearings, each bearing being configured to support a cooperating apparatus for pressing the outer wall of pipe against an inner wall of pipe.

20. The apparatus of claim 10, wherein the apparatus is disposed downstream from a cross-head die configured to extrude the outer wall of pipe onto an inner wall of pipe.

21. An apparatus for forming and cooling an outer wall of polymer onto a corrugated pipe, the apparatus comprising:

a cross-head die configured to extrude an outer wall of polymer onto an inner wall of corrugated polymer pipe;

an annular air manifold positioned downstream from the cross-head die and having an outer diameter and an inner diameter, the inner diameter defining an inner aperture and a plane of the apparatus, a centerpoint of the inner aperture intersecting a pipe-conveying direction;

an air inlet disposed in fluid communication with the annular air manifold; and

22. The apparatus of claim 21, wherein the air inlet is disposed in fluid communication with the annular air manifold at the outer diameter.

23. The apparatus of claim 21, wherein the air inlet is further disposed in fluid communication with an air supply.

24. The apparatus of claim 23, wherein the air supply is a pump.

25. The apparatus of claim 21, wherein the annular passageway is disposed at an angle between 5 and 40 degrees from the plane of the apparatus.

26. The apparatus of claim 21, wherein the annular passageway is disposed at an angle of approximately 15 degrees from the plane of the apparatus.

27. The apparatus of claim 21, wherein the annular passageway is configured to direct air in a downstream direction of a pipe translated through the inner aperture.

28. The apparatus of claim 21, wherein the apparatus comprises a plurality of bearings, each bearing being configured to support a cooperating apparatus for pressing the outer wall of pipe against an inner wall of pipe.