Note: Descriptions are shown in the official language in which they were submitted.
CA 02681901 2009-10-08
APPARATUS AND METHOD FOR COOLING AN OUTER WALL OF PIPE
DESCRIPTION
Technical Field
[001] 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
[002] 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 pine 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.
[003] 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.
[004] 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
1
CA 02681901 2009-10-08
trapped in spaces formed between the extruded outer layer and the exterior
surface of the
polymer pipe.
[005] Accordingly, there is a need for an apparatus and method for cooling an
outer wall of pipe.
Summary
[006] It is an object of the present invention to provide such an apparatus
and
method for cooling an outer wall of pipe.
[007] 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.
[008] 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.
[009] 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
2
CA 02681901 2016-08-08
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.
[010] 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.
[011] The accompanying drawings illustrate certain exemplary
embodiments of the disclosure, and together with the description, serve to
explain
the principles of the invention.
[012] 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 scope of the present invention.
Brief Description of the Drawings
[013] Fig. 1 is a perspective view of an exemplary embodiment of a air-
cooler for cooling an outer wall of pipe;
[014] Fig. 2 is a partial, cross-sectional view of the exemplary air-
cooler
depicted in Fig. 1; and
[015] 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
[016] Reference will now be made in detail to the exemplary embodiments
described above and illustrated in the accompanying drawings.
3
CA 02681901 2016-08-08
[017] 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
3a
CA 02681901 2009-10-08
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.
[018] 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.
[019] 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.
[020] 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
4
CA 02681901 2009-10-08
. .
(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 1800
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.
[021] 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.
[022] 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.
[023] 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 "a," which is disposed at an angle
"0" from
central axis "y." In one embodiment, angle "0" may be between 50 and 40 . In
another
embodiment, angle "0" may be between 10 and 20 . In yet another embodiment,
angle
"0" may be approximately 15 . First ring 18 and second ring 20 may be provided
with any
CA 02681901 2009-10-08
suitable type of mechanism configured to selectively adjust angle "0".
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.
[024] 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.
[025] 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.
[026] 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.
6
CA 02681901 2009-10-08
[027] 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.
[028] 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.
[029] 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
7
CA 02681901 2009-10-08
. .
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.
[030] 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.
[031] Air-cooler 10 may be used to cool outer wall 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
8
CA 02681901 2016-08-08
=
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.
[032] 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
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.
9
