U.S. patent application number 10/417947 was filed with the patent office on 2003-11-06 for novel modified dorn structures.
Invention is credited to DeMeyer, Willy.
Application Number | 20030206989 10/417947 |
Document ID | / |
Family ID | 25091108 |
Filed Date | 2003-11-06 |
United States Patent
Application |
20030206989 |
Kind Code |
A1 |
DeMeyer, Willy |
November 6, 2003 |
Novel modified dorn structures
Abstract
Novel thermoplastic pipes which can withstand extremely high
internally generated and/or applied pressures for utilization
within, primarily, high pressure underground liquid and gas
transport systems are provided. Such pipes are improvements over
standard metal (i.e., steel, lead, and the like) pipes due to
construction costs, shipping costs, implementation costs
(particularly underground), modulus strength allowances to
compensate for underground movements (i.e., earthquakes and
tremors), non-rusting characteristics, and ease in manufacture.
Such pipes are preferably reinforced with specific fabric articles
which permit a lower thickness of plastic to be utilized than is
generally required to withstand high pressure situations. A
simplified, potentially on-site production method for producing
more uniform, better-performing pipes as well as a specific molding
dorn for such a purpose are also contemplated within this
invention.
Inventors: |
DeMeyer, Willy; (Drongen,
BE) |
Correspondence
Address: |
Milliken & Company
P. O. Box 1927
Spartanburg
SC
29304
US
|
Family ID: |
25091108 |
Appl. No.: |
10/417947 |
Filed: |
April 17, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10417947 |
Apr 17, 2003 |
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09771222 |
Jan 26, 2001 |
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Current U.S.
Class: |
425/392 |
Current CPC
Class: |
F16L 55/1656 20130101;
F16L 9/12 20130101; F16L 53/38 20180101 |
Class at
Publication: |
425/392 |
International
Class: |
B29C 033/42 |
Claims
What is claimed is:
1. A molding dorn comprising a first end and a second end with
areas in between said first and said second end, wherein said dorn
exhibits the same diameter over its entire length and wherein said
dorn exhibits a reduction in surface area numerically from said
first end consecutively through all areas in between said first end
to second end and ultimately to said second end.
2. The molding dorn of claim 1 wherein said dorn is substantially
round at said second end.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of co-pending application
Ser. No. 09/771,222, filed on Jan. 26, 2001. This parent
application is herein entirely incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to novel
thermoplastic pipes which can withstand a varied range of
internally generated and/or applied pressures for utilization
within, primarily, underground liquid and gas transport systems.
Such pipes are improvements over standard metal (i.e., steel, lead,
and the like) pipes due to construction costs, shipping costs,
implementation costs (particularly underground), modulus strength
allowances to compensate for underground movements (i.e.,
earthquakes and tremors), non-rusting characteristics, and ease in
manufacture. Such pipes are preferably reinforced with specific
fabric articles that permit a lower thickness of plastic to be
utilized than is generally required to withstand high pressure
situations. A simplified, potentially on-site production method for
producing more uniform, better-performing pipes as well as a
specific molding dorn for such a purpose are also contemplated
within this invention.
BACKGROUND OF THE INVENTION
[0003] Underground transport of liquids and gases has been utilized
for many years. Such underground transport has proven to be the
most efficient and safest manner in which to transport potentially
explosive, flammable, and/or toxic liquids (such as crude oil, for
example) and gases (such as methane and propane, as examples) long
distances. The principle method followed to provide such long
distance underground transport has been through metal tubes and
pipes. In the past, the utilization of metals (such as steel,
copper, lead, and the like) was effective from cost and raw
material supply perspectives. However, with the population growing
throughout the world and the necessity for transporting liquids and
gases to more remote locations increases, the continued utilization
of such metal articles has become more and more difficult for a
number of reasons. Initially, the production of such metal tubes
and pipes must be undertaken through high-temperature production
methods at specific foundries which are normally located a
substantial distance from the desired installation site. Such
off-site production thus requires transport of cumbersome metal
articles to the installation location and then subsequent placement
into already-dug channels. These procedures are, again, difficult
to follow since metal articles are rather heavy and must be
connected together to form the desired pipeline. Additionally, in
order to reduce the number of connections between individual pipes,
longer metal pipes could be formed, which adds to the complexity
with an increase in required welded connections. Further problems
associated with metal pipes and tubes include, without limitation,
the potential for rusting (which may contaminate the transported
liquid or gas), the low threshold of earth-shifting which could
cause a break within the pipeline, and the difficulty in replacing
worn out metal pipes in sections, again due to the metal pipe
weight, metal pipe length, and connection welds. These break
problems have proven to be extremely troublesome in certain
geographic areas which are susceptible to earthquakes and tremors
on a regular basis. When such unexpected quakes have occurred in
the past, the metal gas and liquid pipelines have not proven to be
flexible enough to withstand the shear forces applied thereto and
explosions, leaks, or discontinued supplies to such areas have
resulted. These metal articles have remained in use because of
their ability to withstand high pressures. Furthermore, although
such metal pipes are designed to withstand such high pressures
(i.e., above 80 bars, for instance), once a crack develops within
the actual metal pipe structure, it has been found that such cracks
easily propagate and spread in size and possibly number upon the
application of continued high pressure to the same weakened area.
In such an instance, failure of the pipe is therefore imminent
unless closure is effectuated and repairs or replacements are
undertaken.
[0004] Although there is a need to produce new pipelines to remote
locations around the world, there is also a need to replace the
now-deteriorating pipelines already in use. Aging pipelines have
recently caused great concern as to the safety of utilizing such
old articles. Unexpected explosions have occurred with tragic
consequences. Thorough review and replacement of such old metal
pipes is thus necessary; however, due to the difficulties in
determining the exact sections of such pipelines which require
replacement, there is a desire to completely replace old pipelines
but following the same exact routes. Again, due to the difficulties
noted above, there is a perceived need to develop more reasonable,
safer, longer-lasting, easier-to-install, non-rusting, non-crack
propagating, and more flexible pipeline materials. To date, there
have been some new thermoset or thermoplastic articles which are
designed to withstand rather low pressure applications (i.e., 20
bars or below) and which include certain fiber-wound reinforcement
materials (including fiberglass, polyaramids, polyesters,
polyamides, carbon fibers, and the like). However, the resultant
articles do not include specific textile reinforcements (they are
fibers wound around specific layers of plastic material) and thus
are difficult and rather costly to produce. Furthermore, such
fiber-wound materials cannot be easily produced at the pipe
installation site again due to the complexity of creating
fiber-wound reinforcement articles subsequent to thermoplastic or
thermoset layer production. Additionally, with such off-site
production, transport and in-ground placement remain a difficult
problem. Thus, although some improvements have been provided in the
past in relation and in comparison to metal pipes and tubes, there
simply is no viable alternative presented to date within the
pertinent prior art which accords the underground liquid and gas
transport industry a manner of replacing such high pressure metal
articles.
[0005] Additionally, prior attempts at producing reinforced
resinous pipes have uncovered other problems with such final
products, most notably non-uniformity in both the thickness of the
pipe walls as well as the shape of the pipe itself. With such
non-uniformity, limitations as to pressure resistance may occur,
particularly due to the weakening of discrete areas of the pipe to
a greater degree than the other areas of the same article. In such
a situation, even with reinforcements present to provide greater
elongation at break for the entire article, there still exists a
potential problem with greater stress being placed on the weakest
portion of the pipe upon exposure to higher pressures. Thus, a
procedure to produce a more uniform thermoplastic, preferably
reinforced, pipe article is necessary to provide greater security
and more reliable pipes over the lifetime of use of such an
article. Since such thermoplastic or thermoset articles do not
return to their original shape and/or thickness after pressure
stresses have thinned the walls through expansion, again, there is
a great need to produce a more uniform article to defend against
uneven thinning.
[0006] Furthermore, upon utilization of reinforcements, such as
without limitation, fiber-wound tapes (such as polyaramids, and the
like), textile layers (including, scrim, non-woven, woven, and the
like fabrics) in-laid or surrounding at least one layer of resinous
material, and the like, it is imperative that effective adhesion be
effectuated between the resinous layer and the reinforcement
material. In the past, wrapping of fiber-wound material around the
target resin has been practiced with the possible inclusion of an
adhesion promoter formulation to aid in adhesive effects. Also,
since such wrapping must be performed on molten resin to achieve
sufficient adhesive characteristics, the cooled resin thus adheres
more readily to the already-in-place reinforcement material.
However, even with such a procedure, there is no specific guarantee
that appreciable amounts of molten resin will effectively enter the
interstices of the particular wrapped tape material. Thus, a more
reliable method is necessary to provide better adhesion between
resin and reinforcement material. Any method of providing this
benefit as well as the aforementioned greater uniformity in shape
and wall thickness is thus of great importance to the resin pipe
article industry. Unfortunately, to date, no such method has been
provided, taught, or even mentioned within the pertinent prior art
or anywhere within the industry.
OBJECTS OF THE INVENTION
[0007] It is thus an object of this invention to provide such a
viable alternative method for replacing or overcoming the
shortcomings and difficulties of high pressure (i.e., from about 20
to about 100 bars) underground metal pipes and tubes. Another
object of this invention is to provide a suitable fabric
reinforcement system which permits a relatively low amount of
thermoplastic or thermoset composition to be utilized in order to
produce a pressure-resistant thermoplastic pipe article. Yet
another object of this invention is to provide an interlocking
mechanism to best ensure the textile reinforcement layer remains in
place during and after introduction of the outer thermoplastic or
thermoset layer. Still another object of this invention is to
provide a suitable simplified method of producing a resinous pipe
article of substantial uniformity in wall thickness and shape as
well as, if such article includes a reinforcement material, greater
degrees of adhesion between the resin component and reinforcement
component of such pipes. Also, another object is to provide a novel
dorn article for the purpose of initially applying reinforcement
material to resin component which then cools as the combined
materials move along the dorn to form the aforementioned uniform
and greatly adhered together article. Alternatively, the dorn may
be utilized on a resin component alone to provide a uniform shape
and/or wall thickness for the resultant pipe, if desired.
SUMMARY AND BRIEF DESCRIPTION OF THE INVENTION
[0008] Accordingly, this invention encompasses a method of
producing a resinous pipe comprising at least one layer of
thermally manipulated polymeric material, wherein said polymeric
material is first heated and applied around a first end of a
molding dorn having a first end and a second end as well as areas
in between, and subsequently moved along the length of said dorn to
said second end of said dorn and eventually cooled, wherein said
dorn exhibits the shape diameter throughout its entire structure,
but exhibits a greater surface area at said first end than at said
second end. Preferably, said dorn also exhibits a reduction in
surface area numerically from said first end through all areas in
between said first end to second end and ultimately to said second
end. Preferably, said second end is perfectly round in shape.
Clearly, if the first end of the dorn must have a greater surface
area (with the same diameter as the second end), then it must
exhibit a roughened surface or, at least, indentations throughout.
The term "diameter" in such an instance is intended, for the first
end, to indicate the greatest distance from the greatest extension
of the surface (at its greatest measure from the middle of the
dorn) to the surface exactly opposite. In order to provide the
desired uniformity of shape and wall thickness, such diameter must
be the same as that of the second end (which should be
substantially round, as noted above). Without such a specific
diameter, such uniformity would not be possible, as the walls would
not remain at the same thickness at all points on the dorm. More
importantly, however, once the resin is applied around the dorn
itself, if the overall diameter of the dorn is altered, the
resultant molded pipe will exhibit the aforementioned problems of
non-uniform wall thickness or uneven shape. The pipe made therefrom
said method and therewith said dorn comprises at least one layer of
textile reinforcement material, adhered to at least one thermally
manipulated polymeric material or, preferably such textile
reinforcement material is sandwiched between at least two distinct
layers of such thermally manipulated polymeric material, wherein
the elongation at break exhibited by such a pipe is limited solely
to the elongation at break exhibited by said textile reinforcement
material, and wherein said textile reinforcement material exhibits
an elongation at break of at most 50%, preferably at most 30%, more
preferably at most 20%, still more preferably at most about 15%,
even more preferably at most about 10%, and most preferably at most
6%. Preferably said pipe is constructed to withstand at least 100
bars of internal pressure before exceeding the elongation at break
limit. An alternative yet also preferred embodiment is a pipe which
exhibits at most 20 bars of pressure of internal pressure before
exceeding the elongation at break limit and a wall thickness of
said polymeric material of at most {fraction (1/15)}th of the
diameter of said pipe, preferably at most about {fraction
(1/25)}.sup.th, more preferably at most about {fraction (1/50)},
and most preferably at most about {fraction (1/100)}th. Such pipes
thus exhibit wall thicknesses of from about 0.5 millimeter to about
20 millimeters (and potentially thicker, if desired). Also
contemplated within this invention is the pipe as noted above
wherein the textile reinforcement material introduced within said
pipe is a flat structure having a first side and a second side
which is formed into a tubular structure around the inner polymeric
layer upon overlapping contact of said first and second sides and
which possesses means to adhere or interlock said overlapped first
and second sides.
[0009] The term "thermally manipulated polymeric material" is
intended to encompass the well known polymeric compositions of a)
thermoplastics and b) thermosets. Such terms are well known and
describe a) any synthetic polymeric material that exhibits a
modification in physical state from solid to liquid upon exposure
to sufficiently high temperatures and b) any synthetic polymeric
material that exhibits orientation in a preselected configuration
upon exposure to sufficiently high temperatures. Most notable of
the preferred thermoplastic types of materials are polyolefins
(i.e., polypropylene, polyethylene, and the like), polyester (i.e.,
polyethylene terephthalate, and the like), polyamides (i.e.,
nylon-1,1, nylon-1,2, nylon-6 or nylon-6,6), and polyvinyl halides
(i.e., polyvinyl chloride and polyvinvyl difluoride, as merely
examples). Preferred within this invention are polyolefins, and
most preferred is polypropylene. Such materials are generally
petroleum byproducts and are readily available worldwide. These
materials are produced through the polymerization of similar or
different monomers followed by the melt extrusion of the
polymerized materials in pellet form into the desired shape or
configuration. Upon solidification through cooling, such materials
exhibit extremely high pressure resistance, particularly upon
introduction of nucleating agents, such as substituted or
unsubstituted dibenzylidene sorbitols, available from Milliken
& Company under the tradename Millad.RTM., and/or certain
sodium organic salts, available form Asahi Denka under the
tradename NA-i 1M. Such nucleating agents are either mixed and
provided within the pelletized polymers, or admixed within the
melted polymer composition prior to extrusion. These compounds
provide strength enhancements and accelerate thermoplastic
production by producing crystalline networks within the final
thermoplastic product upon cooling at relatively high temperatures.
Theoretically, at least, with a stronger initial thermoplastic
product, the more durable and potentially longer functional
lifetime provided by such a product. Preferred thermoset materials
include materials such as polyurethane, polycarbonate, or the
like.
[0010] Since pipe diameters utilized for largescale underground
transport applications are generally measured in feet rather than
inches or millimeters, the wall thicknesses required to provide the
desired high pressure characteristics are extremely high for
thermoplastics or thermosets alone. Although such thermoplastic
and/or thermoset materials provide certain pressure resistances, in
general the wall thickness required to withstand pressures of about
80 bars requires a standard diameter to wall thickness ratio of at
most 11:1 (for polyethylene for example). Thus, in order to provide
such high pressure characteristics without exceeding the elongation
at break limits of the polymeric materials present in pipe form
(i.e, substantially cylindrical), with pipe diameter of, for
example, about 232 millimeters (about 9 inches), the wall thickness
of the pipe must be at least about 21 millimeters, or about 0.85
inches) to withstand such high pressures. Even with such thick
walls, the polymeric materials would not provide any resistance to
crack propagation should a weakened area of the pipe produce such a
burst point. There is a strong desire to increase the pressure
resistance (and thus consequently, the elongation at break
characterstics) of the target polymeric pipe material in order
either to provide much thinner wall thicknesses without a loss in
pressure resistance as compared with the standard polymeric
materials alone, or to provide greater pressure resistant
thick-walled pipes which are more reliable upon exposure to very
high pressure situations. Such desirable benefits have been
unavailable through practice of a relatively simple manufacturing
method with actual textile reinforcement materials providing the
basis of pressure resistance for the entire pipe article.
[0011] Apparently, upon application of internal pressure within
such non-reinforced thermoplastic and/or thermoset piping
materials, the materials expand in the direction dictated by the
pressure therefore thinning the wall thickness either to the point
of breaking (i.e., to the elongation at break limit) or until the
pressure is discontinued. After discontinuing the pressure,
however, the pipe walls do not return to their original
thicknesses. Also, if the pressure is applied unevenly, or if there
is a discrete area within the thermoplastic or thermoset pipe wall
which is already thinner than the other areas, then the pipe will
more easily burst in relation to the pressure buildup or in
relation to the thinner wall portion. In order to alleviate such
detrimental expansion and burst possibilities within thermoplastic
piping materials, reinforcing materials have been developed to
compensate for such problems. However, in the past, such piping
materials have been limited primarily to hoses and short tubes
(i.e., automobile tubing) which did not require the ability to
withstand extremely high pressures.
[0012] It has now been found that the incorporation of certain
textile reinforcement materials permit reduction of the diameter to
wall thickness ratio for standard thermoplastic and/or thermoset
materials by at least a factor of 1.5 (a ratio for any
thermoplastic of at the most 1:17 in order to withstand a pressure
of at least 80 bars). Preferably, then, the thickness of the
inventive pipe walls should be no greater than about {fraction
(1/17)}.sup.th of the pipe diameter; more preferably no more than
about {fraction (1/20)}.sup.th, and most preferably no greater than
about {fraction (1/25)}.sup.th of the pipe diameter. The term
"withstand pressure" is intended to encompass the ability to
prevent elongation of the entire pipe material to a point of
breaking or weakening in discrete areas (i.e., thinning of certain
areas to permit leakage). Such ability to withstand pressure is
imperative since the utilization of high pressures internally
provides a consistent and continuous force seeking equilibrium with
the external pressures. Any excess thinning of the pipe material
would therefore most likely result in bursting of the pipe due to
physical requirements of equaling pressures. Such textile
reinforcement materials thus aid in the reduction of elongation of
the thermoplastic or thermoset pipe components upon application of
high pressures therein. As noted previously, it has been determined
that the elongation at break of such textile reinforcements
provides the overall elongation at break exhibited by the target
pipe article, particularly upon the presence of such reinforcement
materials between at least two distinct layers of thermoplastic or
thermoset materials. In such a manner, the entire article relies
primarily upon at least one textile reinforcement layer to provide
the desired high elongation at break limit and the low crack
propagation exhibited by the reinforced thermoplastic or thermoset
material. Furthermore, such a reinforcement material also aids in
providing an increased tear resistance to the overall pipe article
which aids in reducing the chances of a breach in structural
integrity as a result of external shear force application (i.e.,
earth tremors, and the like). Since there is strict reliance upon
such properties exhibited and provided by the textile reinforcement
layer, the amount of thermoplastic or thermoset materials can be
substantially reduced with no reduction in reliability under
pressurized situations. Also, if so desired, the user may still
utilize a substantial amount of thermoplastic or thermoset material
in combination with the sandwiched textile reinforcement layer or
layers with confidence that, again, the inventive pipe article will
exhibit improved and reliable pressure resistance, crack
propagation resistance, and tear resistance.
[0013] Of enormous importance in this instance is the flexibility
exhibited by the inventive pipes when subjected to external shear
forces, for example earth tremors, and the like. Such flexibility
permits the pipes to exhibit some movement in relation to the shear
forces generated by such external occurrences. In the past, as
noted above, metal pipes suffered from the lack of flexibility in
that the application of such external shear forces would result in
the burst of certain pipes due to such external forces exceeding
the shear force threshold possessed by the metal materials. Such
flexibility is most suitably measured in terms of tear resistance
to the overall pipe article. In general, metal pipes exhibit at
most a tear resistance of about 6% (copper exhibits the highest
such tear resistance), which is extremely low when the potential
for very strong shear forces underground are significant
(particularly in certain parts of the world prone to earth tremors,
earthquakes, and the like). The thermoplastics and/or thermosets
provide initial tear resistance measurements in excess of at least
20%, with a potential high measurement of more than about 100%,
particularly upon incorporation of the sandwiched textile
reinforcement material as discussed above. Thus, the inventive
pipes should be able to withstand enormous shear forces, at least
better than metal pipes, due to their exhibited tear resistance and
thus flexibility characteristics.
[0014] As noted above, preferably at least two layers of such
thermoplastic and/or thermoset materials are present within the
inventive thermoplastic and/or thermoset pipes. These layers are
separated, at least in part, by a textile reinforcement material.
The total wall thickness of the inventive pipe, as noted above, is
dependent upon the discretion of the producer and in relation to
the properties provided by the textile reinforcement layer itself.
If a thin-walled, low pressure pipe is desired, then the typical
wall thickness may be anywhere from about 4 to about 15
millimeters. A higher elongation at break characteristic exhibited
by the textile reinforcement permits lower thicknesses to be
utilized. Such elongation at break characteristics are generally
measured by the amount of force such textile reinforcements may
withstand. Thus, a textile exhibiting at least an elongation at
break of about 2-3% (i.e., similar to that exhibited by steel but
greater than for most thermoplastic and/or thermoset compositions)
is desired. Of course, textile materials exhibiting far in excess
of this elongation at break minimum are more preferred, with no
real maximum level, only that which may deleteriously affect the
overall stiffness of the product, thereby potentially providing
tear resistance problems. The elongation at break level for
preferred textile reinforcements is determined by a number of
factors, including the tenacity of the constiruent fibers within
the textile (a higher dtex provides a stronger textile overall),
the angle of contactin relation to the direction of the pipe
(angles of form 40 to 70.degree. are preferred, while specific
angles of between 45 and 65.degree. and 50 and 55.degree. are more
preferred, respectively. An angle of specifically 54.degree.44' has
been found to provide the greatest overall strength to the target
pipe article. Thicker layers of textile reinforcement material also
appear to provide stronger overall products, as do scrim and
in-laid textiles.
[0015] The term "textile reinforcement material" or "textile
reinforcement" or "textile reinforcement layer" simply requires a
combination of individual yarns or fibers in a configuration which
is an integrated two-dimensional article prior to incorporation
between the at least two layers of thermally manipulated polymeric
materials. Thus, wound strips incorporated over a completed inner
layer is not encompassed within such a definition. Nor are
fiber-containing tape articles which are also wound around a formed
polymeric pipe article. The specific textile reinforcement
materials may be of any particular configuration, shape, and
composition. The inventive textile reinforcements are present as at
least a single layer of material with a total aggregate thickness
of at least about 500 microns, preferably at least about 400
microns, more preferably at least about 300, and most preferably up
to about 300 microns. Such textiles preferably exhibit a mesh
structure between the two layers of thermoplastic and/or thermoset
materials. In general, it is highly desired that synthetic fibers,
either alone, or in conjunction with metal threads, be utilized
within the reinforcement materials. Such synthetics are less likely
to be susceptible to deterioration over time due to potential
presence of bacteria, moisture, salts, and the like, within and
around the pipes as they would be positioned underground. However,
with the proper precautions of proper coating, finishing, and the
like, natural fibers may serve this purpose as well. The preferred
textile reinforcements may be knit, scrim, woven, non-woven,
in-laid, and the like, in form, with scrim and in-laid textiles
most preferred. Such forms are most easily produced and maneuvered
during the actual pipe production procedure. With in-laid textiles,
at least two layers are desired to have one layer oriented at one
angle and the other its complement in relation to the direction of
the target thermoplastic pipe. Thus, one layer would be placed with
all yams and/or fibers oriented at an angle of about 54.degree.44'
to the pipe direction, the other oriented at an angle of about
-54.degree. 44'. In order to more easily hold such in-laid fabric
layers in place, a thermoplastic film may be applied either between
or on top of one or both layers. Such a film is preferably
extremely thin (i.e., less than about 200 microns, preferably less
than 100 microns, and most preferably less than about 50 microns)
and, being a thermoplastic, will easily react with the outer layer
of thermoplastic upon heating and molding around the inner
layer/fabric reinforcement composite. Alternatively, sewn threads
may be utilized to hold such multiple layers in place prior to,
during, and after pipe production. Although it is preferred that
such textile reinforcement material is utilized within the
inventive method, as noted previously, such material may be omitted
if very low pressures are desired of the end pipe product. Also,
fiber-wound wrapping (i.e., tapes) may also be utilized for such
purpose within the inventive method (as well as any other
reinforcement means which adheres easily and sufficiently to the
resin components of the target pipe article).
[0016] The yams within the specific textile reinforcement materials
may be either of multifilament or monofilament and preferably
possess a relatively high dtex, again, to provide the desired
tenacity and strength to the overall pipe article. A range of
decitex of from about 200 to about 24,000 is therefore acceptable.
Mixtures of such individual fibers may be utilized as well as long
as the elongation at break of the complete textile reinforcement
material dictates the elongation at break for the complete
thermoplastic and/or thermoset article. Multifilament fibers are
preferred since they provides better adhesive properties and
greater overall strength to the textile. The individual fibers may
be of polyester, polyamide, polyaramid, polyimide, carbon,
fiberglass (silicon-based, for example), boron-derivative, and
possibly, polyolefin, in nature. Again, natural fibers, such as
cotton, wool, hemp, and the like, may be utilized but are not as
trustworthy as the synthetitic types listed above. Due to high
processing temperatures associated with polymeric pipe extruding,
it is highly desirable to avoid the sole utilization of low
melting-point polyolefin yams. However, a plurality of individual
fibers of such polyolefins (i.e., polypropylene, polyethylene, and
the like) may be utilized in combination with the other synthetic
fibers in order to improve adhesion upon melting of such yams upon
exposure to the higher temperatures present during the contacting
of the textile reinforcement to the thermoplastic and/or thermoset
inner and outer layers. Fiberglass and boron-derivatives are
preferred due to their strength characteristics and their alkaline
resistance. The remaining fibers are also acceptable, including,
most prominently, polyaramids, polyimides, carbon fibers, and
polyesters. Polyesters are desirable from a cost standpoint while
the remaining fibers are excellent with regards to strength.
[0017] Of particular preference within this invention are yams of
core-sheath types, as taught within U.S. Pat. No. 5,691,030 to
DeMeyer, herein entirely incorporated by reference. Such specific
yams permit breakage of the sheath components without affecting the
strength of the core filaments therein. Such core filaments may be
monofilament synthetic fibers (such as polyester, polyamides,
polyaramids, polyolefins, and the like), although, in one
potentially preferred embodiment, at least a portion of such core
filaments are metallic in nature (such as, preferably, copper,
silver, gold, and the like) in order to permit conduction of
electrical current and/or heat over the entire pipeline. Such metal
threads, fibers, yams, etc., are not limited to being core
filaments and thus may be present as distinct in-laid, woven, knit,
no-woven, placed, scrim, components. Such metallic components
provide great strength as needed within the fabric reinforcement
materials; however, they also may serve to provide other highly
desirable benefits for both the inventive pipes and the overall
pipeline comprising such pipes. For example, such conductive
components may permit the introduction of a low electrical current
over the entire pipeline (through a continuous connection of metal
components) or through certain segments thereof. In such a manner,
a detection system may be implemented to determine where and at
what time a pipe has burst or a leak is present. Upon interruption
of the desired electrical signal (i.e., the specific amps of
current), a valve may be operated to close off a certain portion of
the pipeline until repairs are made. Such a system merely requires
the connection of an ampmeter to the pipeline and integration of a
valve in relation to the measured amperage flowing through the
pipeline itself. Furthemore, with such a detection system, the
ability to detect such problems from above-ground would be provided
as well as a signal in relation to a low amperage count can be
produced thereby signifying the specific location of the problem.
Such a method thus facilitates detection and replacement of such
thermoplastic pipes.
[0018] Additionally, in certain locations freezing temperatures may
provide difficulty in transporting certain gases and liquids
underground without the ability to provide heated pipes. The
presence of metal yams, etc., facilitates the generation of heat,
potentially, within the desired pipes with, again, the introduction
of certain selected amounts of current and/or heat over the metal
components. The heat generated thereby may be utilized to
effectively keep the desired pipes from freezing thereby permitting
continuous transport therethrough.
[0019] Even upon utilization of a fabric reinforcement material
configured at the preferred angles noted above in relation to the
pipe direction (i.e., 40 to 70.degree., most preferably 55.degree.
), the addition of a cross-yam within each repeating design,
stitch, pattern, etc., configured at an angle of 0.degree. in
relation to the pipe direction is highly desired. Such a cross-yam
permits melting of the entire pipe structure at discrete places in
order to allow for curvatures to be introduced within the pipeline
without deleteriously affecting the strength of the remaining
fabric reinforcement material or compromising the shear strength of
the entire pipe composite, particularly at the specific bent place.
Such an improvement again shows the benefits of thermoplastic highi
pressure pipes since such curvatures may be produced at any angle
and on-site on an as needed basis. Historically utilized metal
pipes required formation of necessary curvatures at the foundry; if
the angle of curvature was incorrect, new parts had to be produced
to compensate for such a mistake. The inventive pipes permit
on-site corrections if necessary.
[0020] It is desirable that the fabric reinforcement materials are
in mesh form and thus exhibit open spaces between the constituent
fibers and/or yarns therein. Such open space should be large enough
to permit a portion of the heated liquid outer thermoplastic layer
to adhere to the already formed inner thermoplastic layer
therethrough and after cooling of the outer layer. In such a
manner, not only is the three layer pipe stronger, the
reinforcement materials are better held in place. Although larger
open spaces between constituent fibers and/or yams are preferred,
the only requirement is that at least a portion of the outer layer
exhibit some ability to adhere with the surface of the inner layer
in contact with the fabric reinforcement materials. Thus, a range
of preferred open space between individual constituent yams of an
area as low as 0.001 square millimeters and as high as about 1
square centimeter is desired.
[0021] The separate polymeric material layers and textile
reinforcement layer may comprise any number of additives for
standard purposes, such as antimicrobial agents, colorants,
antistatic compounds, and the like. Such antimicrobial agents would
potentially protect the inner lining from colonization of unwanted
and potentially dangerous bacteria (which could potentially create
greater pressure within the pipes if a proper nutrition source is
present). Preferably, such an antimicrobial agent would be
inorganic in nature and relatively easy to introduce within the
thermoplastic compositions within the pipe. Thus, silver-based
ion-exchange compounds (such as ALPHASAN.RTM., available from
Milliken & Company, and other types, such as silver zeolites,
and the like) are preferred for this purpose. Colorants may be
utilized to easily distinguish the thermoplastic layers for
identification purposes. Any pigment, polymeric colorant, dye, or
dyestuff which is normally utilized for such a purpose may be
utilized in this respect for this invention. Antistatic compounds,
such as quaternary ammonium compounds, and the like, permit static
charge dissipation within the desired thermoplastic materials in
order to reduce the chances of instantaneous spark production which
could theoretically ignite certain transported gases and/or
liquids. Although the chances of such spark ignition are extremely
low, such an additive may be necessary to aid in this respect.
[0022] Such fabric reinforcement materials provide the
aforementioned resistance to expansion, swelling, and/or burst due
to the application of extremely high internal pressures within the
target thermoplastic pipe material. Preferably, the fabric
reinforcement material is configured at an angle of about
55.degree. (54.degree. 44') in relation to the direction of the
target pipe itself. In such a manner, the fabric provides the best
overall strength and thus resistance to internal pressures due to
its resistance to shear forces generated by the internal pressure
within the pipe. Depending on the amount of fabric utilized,
however, the angle of contact may be as low as 0.degree. and as
high as 90.degree.. With an angle configured in the same direction
as the pipe itself, there is a higher risk of pipe burst due to the
low shear force threshold provided by the fabric. Thicker fabrics
may compensate for such shear force problems; however, the actual
angle of contact should be from about 40 to about 70.degree., with
the particular 54.degree. 44' angle most preferred. Furthermore,
the number of fabric layers utilized may be plural to provide
greater reinforcement strength. In such an instance, it is highly
desirable that contacting layers of fabrics be configured at
opposite angles of contact in relation to the pipe direction to
accord, again, the strongest reinforcement possible. The
utilization of a supplemental textile reinforcement layer oriented
at an angle of contact with the pipe direction of either 0 or
90.degree. imparts certain desirable properties to the overall pipe
article. Most notably, crush resistance is provided to ready-made
pipes which are necessarily wound on a creel for transport to an
installation site. A 0.degree. reinforcement angle provides the
best stiffness to compensate for the weight generated by rolled
pipes. Also, should an initial production of the inner layer be
desired in roll form, the incorporation of such a 0.degree. textile
reinforcement component may alleviate crushing problems associated
with such storage and transport. A 90.degree. orientation improves
upon the tear resistance of the final product.
[0023] Although only two specific layers of thermoplastic and/or
thermoset materials are required, it is to be understood that more
than two such layers are acceptable within this invention. Such
additional layers may be of any type (and not necessarily
thermoplastic and/or thermoset), including, without limitaition,
metal, ceramic, glass-filled plastic, rubber, and the like. Other
alternatives to this inventive article will be apparent upon review
of the preferred embodiments within the drawings as discussed
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] These and other features, aspects, and advantages of the
present invention will become better understood with regard to the
following description, appended claims, and accompanying drawings,
where:
[0025] FIG. 1 shows an embodiment of the present invention
illustrated as the pipe 10;
[0026] FIG. 2 shows a cross-section of the pipe 10 from FIG. 1;
[0027] FIG. 3 shows a partial cross-sectional view of an apparatus
for forming the pipe from FIG. 1;
[0028] FIGS. 4A-H illustrate cross-sectional views of the apparatus
and pipe from FIG. 3, illustrating the method of joining a
reinforcing fabric with an inner wall;
[0029] FIG. 5 illustrates a partial view of a textile for use in
forming the pipe from FIG. 1 with the apparatus in FIG. 3;
[0030] FIG. 6 illustrates a textile for use as the reinforcing
fabric for forming the pipe from FIG. 1 with the apparatus in FIG.
3; and
[0031] FIG. 7 illustrates an apparatus for the in situ formation
and placement of the pipe from FIG. 1.
[0032] FIG. 8 illustrates a cross-sectional view of another
preferred embodiment of a pipe showing the utilization of multiple
textile reinforcement components connected by tapered ends and
placed around the circumference of the resin material.
[0033] FIG. 9 illustrates the inventive molding dorn in
cross-section at its first end (of high surface area) utilized
within the inventive method of producing resin pipes.
[0034] FIG. 10 illustrates the inventive molding dorn in
cross-section at its second end (of low, smooth surface area)
utilized within the inventive method of producing resin pipes.
[0035] FIG. 11 illustrates a side view of the inventive molding
dorn.
[0036] FIG. 12 illustrates the inventive molding in cross-section
at its first end with the resin and textile reinforcement thereto
applied at its initial stage of molding.
[0037] FIG. 13 illustrates the inventive molding in cross-section
at its second end with the resin and textile reinforcement thereto
applied and adhered together at its final stage of molding.
DETAILED DESCRIPTION OF THE DRAWINGS
[0038] Reference will now be made in detail to potentially
preferred embodiments of the invention, examples of which have been
illustrated in the accompanying drawings. It is to be understood
that these are in no way intended to limit the invention to such
illustrated and described embodiments. On the contrary, it is
intended to cover all alternatives, modifications and equivalents
as may be included within the true spirit and scope of the
invention as defined by the appended claims and equivalents
thereto.
[0039] Referring now to the figures, and in particular to FIGS. 1
and 2, there is shown a pipe 10 illustrating one embodiment of the
present invention. The pipe 10 generally includes an inner wall
110, a reinforcing textile 120, and an outer wall 130. The inner
wall 110 is preferably formed of a thermoplastic material, and has
an inner passage surface 111 and an inner wall textile interface
zone 113. The inner passage surface 111 defines the interior of the
pipe 10. The outer wall 130 is preferably formed of a thermoplastic
material, and has an outer surface 133 and an outer wall textile
interface zone 131. The reinforcing textile 120 wraps around the
inner wall 110 and engages the inner wall textile interface surface
133. The reinforcing textile 120 has a sufficient width to surround
the inner wall 110, and have textile overlap sections 121 where the
edges of the reinforcing material overlap around the inner wall
110. A textile locking system 123 is employed between the textile
overlap sections 121 to prevent the ends of the reinforcing
material 120 from separating. The outer wall textile interface
surface 131 engages the reinforcing textile 120 and the outer wall
surrounds the reinforcing textile 120. Such a textile locking
system 123 may alternatively comprise an adhesive composition (such
as, as merely example, heat-activated or pressure-activated
adhesives) which permits a secure, long-term connection between the
overlap sections 121 and thus prevents separation of the two
sections upon pipe production and potential elongation caused by
high internal pressures.
[0040] Referring now to FIG. 3, there is shown a cross section of
an apparatus 200 for forming the pipe 10 in FIGS. 1 and 2. The
apparatus 200 generally includes an inner wall die 210, a mandrel
220, a reinforcing textile guide 230, and an outer wall die 240.
The inner wall die 210 has an inner wall die aperture 211. The
mandrel 220 extends through the inner wall die aperture 211 and
includes an outer surface 221 for forming the inner passage 111 of
the pipe 10 and providing support to the inner wall 110 during the
formation of the pipe 10.
[0041] Still referring to FIG. 3, the reinforcing textile guide 230
is positioned around the mandrel 220 after the inner wall die 210.
The reinforcing textile guide 230 includes an inside textile guide
231 and an outside textile guide 232 for guiding the edges of the
reinforcing textile 120 to position the reinforcing textile 120
around the inner wall 110. In one embodiment of the apparatus 200,
the reinforcing textile guide 230 includes a joint material
injector 235 that is located to insert a material between the
overlap textile sections 121. In yet another preferred embodiment,
the reinforcing textile guide 230 includes a closing roller 237
that presses the overlapping portions of the reinforcing textile
120 together.
[0042] Referring still to FIG. 3, the outer wall die 240 is located
around the mandrel 220 and includes an inside die wall 241 and an
outside die wall 245. The inside die wall 241 of the outer wall die
240 includes an inside die wall aperture 242 to receive the inner
wall 110 and reinforcing textile 120 combination. The inside die
wall aperture 242 has an inside die wall aperture taper 243 for
assisting the inner wall 110 and reinforcing textile 120
combination to transition into the outer wall die 240. The outer
wall die 240 also has an outside die wall 245 with an outside wall
die aperture 246. A passage 223 in the mandrel 220 provides air
pressure to the inside of the pipe 10 at a point after the outer
wall die 240 forms the outer wall 130 on the pipe 10. A connecting
chain 225 secures a plug 224 inside the pipe 10 seals to the
mandrel 220 in order to maintain the pressure from the mandrel 220
within the pipe 10.
[0043] Referring now to FIGS. 1, 2, and 3, in operation, a
thermoplastic material is extruded through the inner wall die
aperture 211 onto the outer surface 221 of the mandrel 220 to form
the inner wall 110 of the pipe 10. The outer surface of the mandrel
220 provides support to the inner wall 110 of the pipe 10 during
the processes of applying the reinforcing textile 120 and the outer
wall 130. After the inner wall 110 has been extruded onto the
mandrel 220, the reinforcing textile guide 230 positions the
reinforcing textile 120 onto the inner wall textile interface zone
113.
[0044] Referring now referring to FIGS. 3 and 4A-H, the inside
textile guide 231 and the outside textile guide 232 guide opposing
ends of the reinforcing textile 120 as the reinforcing textile 120
is positioned onto the inner wall textile interface zone 113. FIGS.
4A-H illustrate the sequence of how the reinforcing textile guide
230 apply the reinforcing textile 120 onto the inner wall textile
interface zone 113 of the inner wall 110 in a sequential manner.
The inside textile guide 231 first applies one edge of the
reinforcing textile 120 to the inner wall 110 of the pipe 10. As
the inner wall 110 of the pipe 10 progresses along the extruding
apparatus 20, the outside textile guide 232 continues to wrap the
reinforcing textile 120 around the textile interface zone 113 of
the inner wall 110. In this manner, the reinforcing textile 120
surrounds the inner pipe 110 in a way that reduces the possibility
of wrinkles in the reinforcing textile 120 or air pockets between
the inner wall 110 and the reinforcing textile 120.
[0045] Still referring to FIGS. 3 and 4A-H, in one embodiment a
textile locking system 123, in the form of a joint material 123a,
is employed between the textile overlap sections 121 of the
reinforcing textile 120 to assist the reinforcing textile 120 to
remain locked in an overlap position when the finished pipe 10 is
subjected to internal pressures. The joint material 123a is
injected between the textile overlap sections 121 by the joint
material injector 235 just prior to the position that the outside
textile guide 232 joins together the textile overlap sections 121.
The joint material 123a can be the same type of material that is
used to form the inner wall 110, the outer wall 130, or a different
material selected to help secure the textile overlap sections 121
from separating. In another embodiment, the joint material 123a is
a tape, ribbon, strand, or the like that is placed into position
between the textile overlap sections 121 prior to the textile guide
230 joining together the textile overlap sections 121.
[0046] In an alternative yet preferred embodiment, the textile
locking system 123 is a mechanical locking system utilizing
mechanical devices such as hooks, piles, or other mechanical
mechanisms. In a version of the textile locking system
incorporating hook devices, a plurality of hook devices extending
up from the lower textile overlap section 121 into the upper
textile overlap section 121, down from the upper textile overlap
section 121 into the lower textile overlap system, or both. The
textile locking system 123 using hook devices can use hook devices
similar to the hook devices in a hook and pile closure system. In a
version of the textile locking system 123 that employs a pile type
element, the pile type element can extend from the lower textile
overlap section 121 into the upper textile overlap section 121,
from the upper textile overlap section 121 into the lower textile
overlap section 121, or both. The textile locking system 123 using
a pile type element can have a pile type element formed from the
same fibers or yams of the reinforcing material, and can also have
the pile elements canted to angle back towards the center of the
reinforcing textile 120. In another embodiment, the textile locking
system 123 employing a mechanical device can incorporate the
mechanical device onto a ribbon, strip, strand, or the like that is
placed into position between the textile overlap sections 121 prior
to the textile guide 230 joining together the textile overlap
sections 121. The textile locking system 123 employing a mechanical
device in the form of a ribbon, strip, strand, or the like, the
locking system 123 can also be positioned below the lower textile
overlap section 121 and extend up into both textile overlap
sections 121, or above the upper textile overlap section 121 and
extend down into both textile overlap sections 121. Additionally
the textile locking system can employ both the joint material 123a
and the mechanical systems described above.
[0047] Referring back now to FIG. 3, once the textile locking
system 123 is located in place, the closing roller 237 presses the
textile overlap sections 121 together in preparation for applying
the outer wall 130. The outer wall 130 is formed around the inner
wall 110 and reinforcing textile 120 combination by the outer wall
die 240. The inner wall 110 and reinforcing textile 120 combination
enters the outer wall die 240 through the inside wall aperture 242
of the outer wall die 240. The inside wall aperture taper 243
assists the inner wall 110 and reinforcing textile 120 combination
transition into the outer wall die 240. A thermoplastic material is
extruded into the outer wall die 240 and surrounds the inner wall
110 and reinforcing textile 120 combination. The inner wall 110,
reinforcing textile 120, and outer wall 130 exit the outer wall die
240 through the outside die wall aperture 246 in the outside die
wall 245. The outside wall die 240 is illustrated in FIG. 3 as
being perpendicular to the pipe 10; however, it is contemplated
that the outside wall die 240 can be at an angle such that the
inside wall a inside die wall 241 and the outside die wall 245 form
an acute angle to the inner wall 110 and reinforcing textile 120
combination entering the outer wall die 240. This acute angle
facilitates the forming of the outer wall 130 on the pipe 10 and
helps reduce the tendency of the thermoplastic material to leak out
of the inside die wall aperture 242.
[0048] Still referring to FIG. 3, air pressure applied to the
passage 223 in the mandrel 220 exits into the interior of the pipe
10 after the outer wall 130 has been formed. The plug 225 inside
the pipe 10 helps retain the pressure inside the pipe 10. A
connecting chain 227 holds the plug 225 adjacent to the mandrel
220. The pressure applied within the pipe 10 prevents collapse of
the entire structure as the three layer pipe 10 hardens into its
final shape. After hardening, the plug 225 is removed and the
resulting pipe structure 10 is ready for utilization in tandem with
other such pipes (not illustrated) as an entire high pressure
pipeline (not illustrated).
[0049] Referring now to FIG. 5, there is shown a partial view of a
textile 300 for use as the reinforcing textile 110 illustrated in
FIGS. 1 and 2. The textile 300 includes electrode elements 311 and
312, and resistive elements 320. As illustrated in FIG. 5, the
electrode elements 311 and 312 are conductive materials that run
parallel along the length of the textile 300 as the selvage yams.
The resistive elements 320 are woven around the electrode elements
311 and 312, and interlaced to form a fabric. As an example, the
resistive elements 320 can be a yam formed of a flexible core
having a fine resistance wire or tape wound spirally thereon, or
having a layer of carbon particles bonded thereon by a
thermoplastic or resin binder. The electrode elements 311 and 312,
and the resistive elements 320 are flexible to form a fabric that
can be placed around the inner wall 110 as the reinforcing fabric
120 illustrated in FIGS. 1 and 2.
[0050] Referring now to FIGS. 1-2 and 5, by using the textile 300
in FIG. 5 as the reinforcing fabric 120 in FIGS. 1 and 2, an
electrical current can be applied to the electrode elements 311 and
312 of the fabric 300 when in place within the pipe 10. The
electrical current supplied to the electrode elements 311 and 312
passes through the resistive elements 320 and generates heat. In
this manner, the pipe 10 can be used to apply heat to the contents
of the pipe 10, or to compensate for the loss of thermal energy
from the contents of the pipe 10 to the exterior of the pipe.
[0051] Referring now to FIG. 6, there is shown another embodiment
of a textile 400 for use as the reinforcing textile 120 of the pipe
10 in FIGS. 1 and 2. The fabric 400 generally comprises selvage
yams 430, electrode yams 411 and 412, and resistive yams 420. The
electrode yams 411 and 412 are woven around the selvage yams 430
such that a resistive yam 420 separates each electrode yam 411 and
412. At each intersection of the electrode yams 411 and 412, the
electrode yams 411 and 412 are insulated from making an electrical
connection to each other. At each intersection of the resistive yam
420 with one of the electrode yams 411 and 412, the resistive yam
420 is placed in electrical connection with the respective
electrode yam 411 or 412. In this manner, an electrical circuit is
formed having the electrodes 411 and 412 interconnected by a series
of segments from the resistive yam 420, thus forming a parallel
resistive circuit. The parallel resistive circuit can generate heat
in a similar manner to the textile 300 by applying an electrical
current between the electrode yams 411 and 412. Additionally, any
break in yam electrode 411 or 412, will create a change in the
electrical potential across the electrode yarns 411 and 412,
indicating a location of the break. Therefore, a break within the
pipe 10 causing a break of one of the electrodes 411 or 412, can be
located by measuring the electronic potential across the electrode
yams 411 and 412.
[0052] In addition to the textiles 300 and 400 illustrated in FIGS.
5 and 6, a traditional woven or knitted textile having thermal
generating elements can be incorporated as the reinforcing textile
120 illustrated in FIGS. 1 and 2. For example, a traditional woven
fabric having selvage yams, pick yams, and filling yams, can
incorporate the thermal heating aspects of the textiles 300 and
400. The picks of a traditional woven fabric can be the resistive
elements, and the selvage yards and/or fill yams can be a
conductive material. Alternatively, the fill yams can be formed of
a resistive material, and the pick yarns can be conductive yams
which are electrically supplied by conductive selvage yams and/or
conductive fill yams. In yet another embodiment, the resistive yams
can be a combination of pick and fill yams.
[0053] Referring now to FIG. 7, there is shown an apparatus 500 for
the in situ formation and placement of an embodiment of the pipe
from the present invention. The apparatus 500 includes a
transportation device 510 such as a truck, a trench or ditch
digging device 520 located on the transport device 510, and an
apparatus for formation of the pipe 530 such as the pipe forming
apparatus 20 in FIG. 3. A supply of reinforcing textile 540 (such
as a roll of the reinforcing textile 120 in FIG. 1) is positioned
with the transportation device 510 to supply the pipe forming
device 530 with the necessary reinforcing material 120 to form the
pipe 10. Additionally, an extruding device 550 with a plastic
supply 551 is positioned with the transportation device 510 for
supplying melted material to the inner wall dye 210 of the pipe
forming apparatus 200 for forming the inner wall 110 of the pipe
10. A second extruding device 560 with a material supply 561
extrudes material and supplies the material to the outer wall die
240 of the pipe forming apparatus 530 for forming the outer wall
130 of the pipe 10. Although the two extruding devices 550 and 560
have been illustrated as a separate supply, it is contemplated that
the two extruding devices could be a single extruding device.
[0054] Still referring to FIG. 7, the ditch or trench digging
device 510 removes material from the ground for placement of the
pipe 10. The extruding apparatus 520 receives extruded material
from the extrusion device 550, reinforcing material 20 from the
supply, and extruded material from the extrusion device 560 for
forming the inner wall 110, reinforcing textile 120, and outer wall
130, respectively, of the pipe 10. The pipe 10 is positioned within
the trench or ditch formed by the trench or ditch digging device
520 and earth is placed over the pipe 10 as necessary. The process
is continuous allowing the transportation device 510 to form and
place the pipe 10 in situ.
[0055] FIG. 8 thus shows four separate textile reinforcement
materials 610, 620, 630, 640, each with individually tapered ends
612, 614, 622, 624, 632, 634, 642, 644, that have been arranged
around the circumference of the target resin pipe 602. Upon
contacting of these materials 610, 620, 630, 640, as shown, the
tapered ends 612, 614, 622, 624, 632, 634, 642, 644, overlap with
each other and, upon introduction of molten resin which then cools,
the reinforcement materials 610, 620, 630, 640 thus adhere not only
together, but also with the resin materials 602, thereby providing
a reinforced pipe 602.
[0056] FIG. 9 shows one preferred embodiment of an inventive
molding dorn 700. The end shown 702 comprises a plurality of
similarly shaped indentations 704 which thus creates a very large
surface area thereon. FIG. 10 shows the other end 706 of the same
preferred inventive molding dorn 700 of FIG. 9. The diameter
thereof of the second end 706 is the same as that measured to the
greatest extension of the indentations 704 of the first end 702.
FIG. 11 thus shows the same preferred inventive molding dorn 700 of
FIGS. 9 and 10, depicting the modification of surface area (through
indentations 704) of the dorn 700. The number and amount of
indentations 704 is gradually and continually reduced as one views
the dorn from the first end 702 to the second end 706. In order to
keep the dorn 700 in place during pipe production, any method can
be employed including adhesion, magnetism, and the like. As shown
in FIGS. 12 and 13, it is thereby easier for the resin components
708 to adhere to one another, or alternatively, for such resin
components to become more thoroughly adhered thereto during molding
to the textile reinforcement materials 710 by permitting the
forcing through of the resin components 708 over the entire length
of the dorn 700 during the molding step. As the first end 702 is of
greater surface area than the other areas of the dorn 700, and
particularly the second end 706, which is round in shape to produce
the ultimately desired round shape of the pipe article. Pressure is
applied to the resin components 708 and textile reinforcement
materials 710 by a wider extrusion device (or mandrel 520 in FIG.
7). The pressure thus exerted presses the resin components 708 and
reinforcement materials 710 to the dorn 700 during extrusion. The
first end (702 of FIG. 9) is preferably heated to a temperature
permitting the resin components 708 to be in molten state
initially. After extrusion over the molding dorn 700, then, the
molded pipe article is permitted to cool into its molded shape.
[0057] The inventive molding dorn may also exhibit or possess
alternative or extra indentations or patterns for other benefits as
well. For example, small corrugated patterns transferred from the
molding dorn to the ultimate inner surface of the subject pipe can
aid in reducing friction within the pipe itself if such pipes are
utilized for the containment of cables (fiber optics, for example).
Since such cables must be pulled through or pushed through the
entire pipe system to effectuate such containment, and such
introduction is performed at high rates of speed, the need to
potentially reduce the friction on the introduced cables (to reduce
the chances of wearing of the cables themselves, for example) is
noticeable. The modification of the molding dorn to provide such a
corrugated pattern (or like alternative pattern for the same
effect) is thus contemplated as at least one alternative in this
invention.
[0058] Having described the invention in detail it is obvious that
one skilled in the art will be able to make variations and
modifications thereto without departing from the scope of the
present invention. Accordingly, the scope of the present invention
should be determined only by the claims appended hereto.
* * * * *