U.S. patent application number 13/463696 was filed with the patent office on 2013-10-03 for grade seal system and method of manufacturing same.
The applicant listed for this patent is Richard W. Roberts. Invention is credited to Richard W. Roberts.
Application Number | 20130259567 13/463696 |
Document ID | / |
Family ID | 49235231 |
Filed Date | 2013-10-03 |
United States Patent
Application |
20130259567 |
Kind Code |
A1 |
Roberts; Richard W. |
October 3, 2013 |
GRADE SEAL SYSTEM AND METHOD OF MANUFACTURING SAME
Abstract
In at least one embodiment, a grade ring system includes an
annular shell formed of a plastic composition and defining an
annular cavity. An in-situ formed core situated in the annular
cavity comprises a plurality of polymer beads expandable by heating
medium which, when expanded, substantially fill the annular cavity.
A method for forming a grade ring is also disclosed.
Inventors: |
Roberts; Richard W.;
(Tecumseh, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Roberts; Richard W. |
Tecumseh |
MI |
US |
|
|
Family ID: |
49235231 |
Appl. No.: |
13/463696 |
Filed: |
May 3, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61616810 |
Mar 28, 2012 |
|
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|
Current U.S.
Class: |
404/17 ;
156/244.11; 264/210.1 |
Current CPC
Class: |
E02D 29/16 20130101;
E02D 29/1409 20130101 |
Class at
Publication: |
404/17 ;
264/210.1; 156/244.11 |
International
Class: |
E02D 29/16 20060101
E02D029/16 |
Claims
1. A grade ring system comprising: an annular shell formed of a
plastic composition and defining an annular cavity; an in-situ
formed core situated in the annular cavity comprising a plurality
of polymer particles expandable by a heating medium which, when
expanded, substantially fill the annular cavity.
2. The grade ring system of claim 1 wherein the plastic composition
is a thermoplastic polymer composition.
3. The grade ring system of claim 1 wherein the plastic polymer
composition comprises a polypropylene composition.
4. The grade ring system of claim 1 wherein the expandable polymer
particles comprise a polyolefin particles.
5. The grade ring system of claim 1 wherein the expandable polymer
particles comprise expanded polypropylene particles.
6. The grade ring system of claim 1 wherein the expandable polymer
particles comprise homopolymer beads.
7. The grade ring system of claim 1 wherein the expandable polymer
particle comprises a steam-expandable polymer bead.
8. The grade ring system of claim 1 wherein the heating medium
comprises super-heated steam.
9. The grade ring system of claim 1 wherein the elongated annular
shell ranges in height from 0.75 inches to 6 inches.
10. The grade ring system of claim 1 wherein the diameter of the
annular shell ranges from 1 inch to 10 inches.
11. The grade ring system of claim 1 wherein the annular ring has
opposed, spaced-apart first and second surfaces, the first surface
includes a protrusion and the second surface includes a recessed
embossment.
12. The grade ring system of claim 1 wherein the annular ring has
opposed, spaced-apart first and second surfaces, the first and
second surfaces are substantially parallel and situated at an angle
relative to the outer wall of the elongated annular ring.
13. The grade ring system of claim 1, wherein the annular ring has
a varying height to define wedge shape in side view.
14. The grade ring system of claim 13 wherein the wedge-shaped
annular ring has opposed, spaced-apart first and second surfaces,
the first and second surfaces being situated relative to each other
at an angle ranging from 0.5 degrees to 10 degrees to allow
alignment with angles of a street surface.
15. A grade ring system comprising: a first annular ring comprising
a first annular tubular shell formed of a first plastic composition
and defining a first cavity, the first annular tubular shell
including a first surface having a protrusion and a second surface
being opposed to and spaced apart from the first surface, the
second surface having an embossment, the first cavity being
substantially filled with an in-situ expanded polymer bead core;
and a second annular ring comprising a second annular tubular shell
formed of a second plastic composition and defining a second
cavity, the second annular tubular shell including a first surface
having a protrusion and a second surface being opposed to and
spaced apart from the first surface, the second surface having an
embossment, the second cavity being substantially filled with an
in-situ expanded polymer bead core, wherein the protrusion of the
second annular ring being capable of engaging the embossment of the
first annular ring when the first annular ring is vertically
stacked up on the second annular ring.
16. The system of claim 15, further comprising a base grade ring
having a base annular tubular shell formed of a third plastic and
defining a base grade ring cavity, the base annular tubular shell
including a base surface having a protrusion, the base cavity being
substantially filled with an in-situ expanded polymer bead core,
wherein the base grade ring is capable of engaging the embossment
of the second annular ring when the second annular ring and the
base annular ring are vertically stacked adjacent to one
another.
17. The system of claim 15, further comprising a cap ring having a
cap annular tubular shell formed of a one or more layers of plastic
and defining a cap ring cavity, the cap annular tubular shell
including a cap surface having a embossment, the cap ring cavity
being substantially filled with an in-situ expanded polymer bead
core, wherein the cap ring is capable of engaging the protrusion of
the first annular ring when the first annular ring and cap annular
ring are vertically stacked adjacent to one another.
18. The system of claim 15, wherein the first surface of either the
first or second annular ring is disposed at an angle relative to
the second surface of the same annular ring, the angle ranging from
0.5 degrees to 10 degrees.
19. The system of claim 15 further comprising a seal disposed
between the embossment of the first annular ring and the protrusion
of the second annular ring.
20. The system of claim 15, wherein a radius of the first annular
ring equals or exceeds the radius of the second annular ring, when
the first annular ring is disposed above the second annular
ring.
21. The system of claim 15, wherein at least one annular ring has a
thickness ranging from 0.75 inches to 6 inches.
22. A method for manufacturing a grade ring system component
comprising the steps of: (a) extruding a plastic preform in a mold
cavity in the shape of an elongated member to form a tubular
plastic shell having a longitudinal axis; (b) forming the tubular
plastic shell to form at least one annular ring shell in a closed
mold having a closing axis substantially transverse to the
longitudinal axis, the annular ring shell having a wall defining a
cavity; (c) forming at least one fill port and a plurality of
heating ports in the wall of the annular ring shell; (d) filling
the cavity through the fill port with expandable polymer particles;
(e) injecting a hot, at least partially vaporized, heating medium
into the heating ports to expand the expandable polymer particles
so as to substantially fill the cavity of the annular ring shell to
form the component; (f) constraining the annular ring shell in the
closed mold to limit expansion caused by the heated, expanding
polymer particles until the component has cooled sufficiently to
limit further expansion; and (g) releasing the component from the
mold cavity.
22. The method of claim 21, further comprising the steps of: (h)
forming at least two components; and (i) stacking at least two
components to form the grade ring system.
23. The method of claim 22, further comprising the steps of: (j)
forming at least one wedge-shaped component wherein the component
has a first surface disposed at an angle relative to an opposed
second surface, the angle ranging from 0.5 degrees to 10 degrees;
(k) situating the first wedge-shaped component on or within the
grade ring system; and (l) adjusting the grade ring system height
or angle relative to a street surface when rotating the first
wedge-shaped component such that the angle of the wedge-shaped
component cooperates with an angle of the street surface to form a
substantially smooth transition between the grade ring systems and
the street.
24. The method of claim 23, further comprising: (m) situating a
second wedge-shaped component in an inverted position on the first
wedge-shaped component; (n) rotating the second wedge-shaped
component relative to the first wedge-shaped component to achieve
the grade angle or height of the street surface.
25. The method of claim 21, wherein the heating ports include steam
injection needles are spaced apart having a spacing ranging from D1
to D2, where D 1 = 1 ( ABD .times. 0.56 ) - 0.5 D 2 = 1 ( ABD
.times. 5 ) + 3 ##EQU00002## and ABD is the average apparent bulk
density of the expandable polymer particles.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/616,810 filed Mar. 28, 2012, the disclosure of
which is incorporated in its entirety by reference herein.
TECHNICAL FIELD
[0002] The disclosed embodiments relate to a grade seal system and
a method of manufacturing same.
BACKGROUND
[0003] Often in the construction of a manhole along a street
construction firms find it necessary to apply adjustment courses in
the immediate area of the manhole cover in order to provide a
smooth transition between the manhole cover and the street. Because
of frequently heavy use and varying stresses on these adjustment
courses, the adjustment courses are prone to rapid deterioration.
Substitution of plastic compositions for the materials in previous
adjustment courses have not alleviated the deterioration of the
adjustment courses as they remain susceptible to ultraviolet light
degradation and freeze-thaw forces.
SUMMARY
[0004] At least one embodiment, a grade ring system includes an
annular shell formed of a plastic composition and defining an
annular cavity. An in-situ formed core is formed of a plurality of
polymer particles expandable by a heating medium which, when
expanded, substantially fill the annular cavity.
[0005] In another embodiment, a grade ring system includes a first
annular ring comprising a first annular tubular shell formed of a
first plastic composition and defining a first cavity. The first
annular tubular shell includes a first surface having a protrusion
and a second surface being opposed to and spaced apart from the
first surface having an embossment. The first cavity is
substantially filled with an in-situ expanded polymer bead core.
The grade ring system also includes a second annular ring
comprising a second annular tubular shell formed of a second
plastic composition and defining a second cavity. The second
annular tubular shell includes a first surface having a protrusion
and a second surface being opposed to and spaced apart from the
first surface. The second surface has an embossment. The second
cavity is substantially filled with an in-situ expanded polymer
bead core. The protrusion of the second annular ring is capable of
engaging the embossment of the first annular ring when the first
annular ring is vertically stacked upon the second annular
ring.
[0006] In yet another embodiment, a method for manufacturing a
grade ring system component includes the steps of blowmolding a
plastic preform in a mold cavity in the shape of an elongated
member to form an elongated tubular plastic shell having a
longitudinal axis. The elongated member is draw-formed to form at
least one annular ring shell in a closed mold. The closed mold has
a closing axis that is substantially transverse to the longitudinal
axis of the elongated member. The annular ring shell defines a
cavity. The annular ring shell receives at least one fill port and
a plurality of heating ports in the wall of the annular ring shell.
The cavity is filled with expandable polymer particles through the
fill port. The expandable polymer particles are expanded to
substantially fill the cavity of annular ring shell by injecting a
hot, at least partially vaporized, heating medium into the heating
ports. The annular ring shell is constrained in the closed mold to
limit expansion caused by the heated, expanding polymer particles
until the component has cooled sufficiently to limit further
expansion. The component is released from the mold.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 schematically illustrates an exploded isometric view
of a manhole including a grade ring system according to at least
one embodiment;
[0008] FIG. 2 schematically illustrates a cross-sectional view of a
grade ring along axis 2-2 of FIG. 1;
[0009] FIG. 3 schematically illustrates a cross-sectional view of a
grade ring according to at least one alternative embodiment;
[0010] FIGS. 4a-4c schematically illustrate varying height using a
plurality of rings having a wedge shape in side view according to
at least one embodiment;
[0011] FIG. 5 schematically illustrates a plan view of a grade ring
according to at least one other embodiment;
[0012] FIG. 6 schematically illustrates a plan view of a grade ring
according to at least another embodiment;
[0013] FIG. 7 schematically illustrates a cross-sectional view
along axis 6-6 of FIG. 5; and
[0014] FIGS. 8a-8e schematically illustrate a process of
manufacture of a grade ring system according to at least one
embodiment.
DETAILED DESCRIPTION
[0015] As required, detailed embodiments of the present invention
are disclosed herein; however, it is to be understood that the
disclosed embodiments are merely exemplary of the invention that
may be embodied in various and alternative forms. The figures are
not necessarily to scale; some features may be exaggerated or
minimized to show details of particular components. Therefore,
specific structural and functional details disclosed herein are not
to be interpreted as limiting, but merely as a representative basis
for teaching one skilled in the art to variously employ the present
invention.
[0016] Except where expressly indicated, all numerical quantities
in the description and claims, indicated amounts of material or
conditions of reaction and/or use are to be understood as modified
by the word "about" in describing the broadest scope of the present
invention. Practice within the numerical limits stated should be
desired and independently embodied. Ranges of numerical limits may
be independently selected from data provided in the tables and
description. The description of the group or class of materials as
suitable for the purpose in connection with the present invention
implies that the mixtures of any two or more of the members of the
group or classes are suitable. The description of constituents in
chemical terms refers to the constituents at the time of addition
to any combination specified in the description and does not
necessarily preclude chemical interaction among constituents of the
mixture once mixed. The first definition of an acronym or other
abbreviation applies to all subsequent uses herein of the same
abbreviation and applies mutatis mutandis to normal grammatical
variations of the initially defined abbreviation. Unless expressly
stated to the contrary, measurement of a property is determined by
the same techniques previously or later referenced for the same
property. Also, unless expressly stated to the contrary,
percentage, "parts of," and ratio values are by weight, and the
term "polymer" includes "oligomer," "co-polymer," "terpolymer,"
"pre-polymer," and the like.
[0017] It is also to be understood that the invention is not
limited to specific embodiments and methods described below, as
specific composite components and/or conditions to make, of course,
vary. Furthermore, the terminology used herein is used only for the
purpose of describing particular embodiments of the present
invention and is not intended to be limiting in any way.
[0018] It must also be noted that, as used in the specification and
the pending claims, the singular form "a," "an," and "the,"
comprise plural reference unless the context clearly indicates
otherwise. For example, the reference to a component in the
singular is intended to comprise a plurality of components.
[0019] Throughout this application, where publications are
referenced, the disclosure of these publications in their entirety
are hereby incorporated by reference into this application to more
fully describe the state-of-art to which the invention
pertains.
[0020] As required, detailed embodiments of the present invention
are disclosed herein; however, it is to be understood that the
disclosed embodiments are merely exemplary of the invention that
may be embodied in various and alternative forms. The figures are
not necessarily to scale; some features may be exaggerated or
minimized to show details of particular components. Therefore,
specific structural and functional details disclosed herein are not
to be interpreted as limiting, but merely as a representative basis
for teaching one skilled in the art to variously employ the present
invention.
[0021] Regarding FIG. 1, a manhole system is illustrated having a
manhole 12 on which is seated a base grade ring 14. Situated on
base grade ring 14 are one or more intermediate grade rings 16.
Situated on top of intermediate grade rings 16 is a cap grade ring
18. Base grade ring 14, intermediate grade rings 16 and cap ring 18
comprise a grade ring system 20. In at least one embodiment, the
grade ring system may comprise one or more of any of the base grade
ring 14, grade ring 16, and/or cap ring 18, such as base grade ring
14 and cap ring 18 or a system embodiment comprising one or more
intermediate grade rings 16, which may be in an annular
configuration.
[0022] In at least one embodiment, intermediate grade rings 16 may
include an optional protrusion 22 situated on at least one surface.
Intermediate grade rings 16 may also include an optional embossment
24 on a surface. It is preferable that protrusion 22 interlocks
with embossment 24 on another ring to assist in positioning
intermediate grade rings 16 and/or other rings. A center opening 26
defined by the annular configuration of the grade rings aligns
substantially concentrically when one or more intermediate grade
rings, such as intermediate grade rings 16, base grade ring 14,
and/or cap ring 18, when the rings are stacked vertically upon each
other to form the grade ring system 20. It is understood that
embossment 24 is illustrated as a recessed embossment, embossments
having a raised portion and/or a mixture of raised portions and
recessed portions are contemplated in certain embodiments.
[0023] It is further preferable that exterior periphery 28 of each
grade ring, such as the base grade ring 14, intermediate grade ring
16, and cap grade ring 18, aligns substantially vertically over the
exterior periphery 28 of other intermediate grade rings when
vertically stacking the rings to form the system 20. Having no
substantial steps may be desirable, particularly in situations
where the exterior periphery 28 of a first grade ring extends
radially a longer distance than the exterior periphery of another
grade ring situated below the first grade ring. Having a step may
allow freeze-thaw forces to move portions of grade ring system 20
allowing water to enter the manhole and/or contribute to
deterioration of the adjustment course (not shown).
[0024] Cap grade ring 18 may be adapted to receive a frame 30
and/or a cover 32.
[0025] In at least one embodiment, cap ring 18 may have a width
ranging from 3 inches to 48 inches. In another embodiment, cap ring
18 may have a width ranging from 4 inches to 10 inches. It is
understood that the width dimension of cap ring 18 is illustrative
of other grade ring embodiments within the scope and spirit of this
invention.
[0026] Turning now to FIG. 2, a cross-sectional view of at least
one embodiment of intermediate ring 16 is illustrated. Intermediate
ring 16 comprises a thermoplastic shell 40 that defines a cavity
42. Cavity 42 is substantially filled with a core 44 filled with
expanded polyolefin beads 46. It should be understood that such a
cross-sectional view may also be illustrative of other grade rings,
such as base grade ring 14 or cap grade ring 18.
[0027] Intermediate ring 16 further includes a first surface 48
that is opposed to and separated from a second surface 50. Exterior
periphery surface 28 is opposed to and spaced apart from interior
periphery surface 52.
[0028] The cross-section of FIG. 2 when revolved around a central
axis exterior to the cross-section forms a circular annular ring.
The width of cross-section, such as between surfaces 28 and 52, may
range from 1 inch to 4 inches in at least one embodiment. In
another embodiment, the width of ring 18 ranges from 2 inches to 3
inches.
[0029] In at least one embodiment, the height of cross-section
between surface 48 and surface 50 ranges from 0.75 inches to 6
inches. In another embodiment, the height of the cross-section
ranges from 1 inch to 5.5 inches.
[0030] A thickness of shell 40 may range from 0.03 inches to 0.5
inches in at least one embodiment. In another embodiment, the
thickness of shell 40 may range from 0.125 inches to 0.25
inches.
[0031] Core 44 may include steam-expandable polymer beads, which
when expanded in-situ within the shell 40, form expanded polymer
beads 46. In at least one embodiment, the expanded polymer beads
include expanded polyolefin beads. In another embodiment, the
expanded polyolefin beads includes expanded polypropylene polymer
beads (EPP) in core 44. In yet another embodiment, core 44 includes
expanded high molecular weight polypropylene polymer beads. In yet
another embodiment, homopolymer beads are included in the expanded
polyolefin beads in order to increase the stiffness of core 44. As
a non-limiting example, when the homopolymer polyolefin is a
homopolymer polypropylene, the stiffness increases such that a
100,000 lb load yields a strain less than 5.8% and a compression
set of less than 0.07 inches. It is understood that a portion of
core 44 may comprise polyolefin beads in an unexpanded
configuration or a partially expanded configuration without
exceeding the scope and spirit of the contemplated embodiments.
[0032] Shell 40 may be formed from a polymeric composition. The
polymeric composition may include a recyclable thermoplastic
composition. Non-limiting examples of the polymeric composition
suitable for shell 40 include polyolefins, such as polypropylene
and polyethylene.
[0033] In certain embodiments, especially when cold, shell 40
includes a blend of a non-polyolefin thermoplastic polymer and
polyolefin (NPTP/PO), such as a thermoplastic
polyolefin/polypropylene blend, a thermoplastic
elastomer/polypropylene blend, a thermoplastic polymer having a
glass transition temperature less than -80.degree. C. and
polyolefin blend, a thermoplastic polymer having a glass transition
temperature less than -20.degree. C. and polyolefin blend, a
thermoplastic vulcanizate/polyolefin blend, and a heterogeneous
polymer blend.
[0034] In certain embodiments, heterogeneous polymer blends have a
crystalline thermoplastic phase and a high molecular weight and/or
crosslinked elastomeric phase such as supplied by ExxonMobil or
Advanced Elastomer Systems.
[0035] In at least one embodiment, the heterogeneous polymer blend
includes the non-crystalline polyolefin thermoplastic polymer
ranges from 5 wt. % to 70 wt. % of the amount of blend. In another
embodiment of the heterogeneous polymer blend, the amount of the
non-crystalline thermoplastic polymer ranges from 10 wt. % to 40
wt. %.
[0036] In at least one embodiment, the ratio of non-polyolefin
thermoplastic polymer to polyolefin in the NPTP/PO blend ranges
from 0.1 to 10 in the heterogeneous polymer blend. In another
embodiment, the ratio of non-polyolefin thermoplastic polymer to
polyolefin in the NPTP/PO blend ranges from 0.2 to 5. In yet
another embodiment, the ratio of non-polyolefin thermoplastic
polymer to polyolefin ranges from 0.3 to 2.
[0037] The core 44, when comprised of EPP steam-bonded to the shell
40, has an ability to withstand greater than 80 lbf/in2 dynamic
load, such as an AASHTO H-20 wheel loading specification.
[0038] The core 44, when comprised of EPP steam-bonded to the shell
40, has the ability to withstand greater than 21,280 lbf static
load when tested according to the method in AASHTO HS-25 highway
bridge specification.
[0039] When the grade ring system is assembled with the base ring
14, the intermediate ring 16, the cap ring 18 and with sealant bead
34 between each ring, water penetration tests showed no leakages at
less than 3'' of hydrostatic head.
[0040] The intermediate grade ring 16 has a weight for a 32''
outside diameter ring with a 24'' inside diameter as follows in
Table 1.
TABLE-US-00001 TABLE 1 Height Weight Prior Art Weight 3'' 10-20 lbs
92 lbs 6'' 20-40 lbs 183 lbs 12'' 40-160 lbs 366 lbs
[0041] A heating medium, such as steam, super-heated steam, or
partially vaporized steam, may be injected into unexpanded or
partially expanded polyolefin beads. Expanded polyolefin beads,
such as EPP, may have a density ranging from 1 lb per cubic foot to
20 lbs. per cubic foot. In yet another embodiment, steam-expanded
EPP may have a density ranging from 1.5 lbs per cubic foot to 10
lbs. per cubic foot. In yet another embodiment, steam-expanded EPP
may have a density ranging from 2 lbs. per cubic foot to 6 lbs. per
cubic foot. In another embodiment, steam-expanded EPP may have a
density ranging from 3 lbs. per cubic foot to 5 lbs. per cubic
foot.
[0042] The steps of expanding unexpanded or partially expanded
beads using a heating medium are illustrated by U.S. patent
application Ser. Nos. 13/358,181, 13/005,190, and 12/913,132, all
of which are hereby incorporated by reference
[0043] Turning now to FIG. 3, in at least one embodiment, a
wedge-shaped grade ring 60 is illustrated. In at least one
embodiment the wedge may have a angle, theta, ranging from
0.5.degree. to 10.degree.. In at least another embodiment, the
wedge-shaped ring 60 may have an angle ranging from 2.degree. to
7.degree.. Wedge-shaped ring 60 in at least one embodiment may have
a first wall 62 and a second wall 64 that define the annular ring
as well as cavity 42 into which core 44 is formed in-situ by using
a heating medium to expand unexpanded and/or partially expanded
polymer beads.
[0044] While embossment 24 is illustrated in at least one
embodiment, it should be understood that other means of inducing
cooperation and/or fastening wedge-shaped grade rings to one
another may be used without exceeding the scope or spirit of the
invention. Non-limiting examples of cooperative structures include
a retention structure, such as a cover having a diameter exceeding
the diameter of the cap ring 18 or intermediate grade ring 16,
protrusions cooperating with embossments on other rings, a
permanent alignment fixture, an adhesive, adhesively-applied
structures, alignment pins, and/or a removable alignment fixture.
For another example, FIG. 3 includes the optional sealant bead 34
positioned to engage a seal between embossment 24 and another
surface. It should be understood that sealant bead 34 may include
an adhesive composition and/or may be formed in any shape needed,
such as a strip, intermittent drops, tape or roll.
[0045] Turning now to FIGS. 4a to 4c, a first wedge-shaped grade
ring 60 is mounted on a second wedge-shaped grade ring 60. By
rotating the first wedge-shaped grade ring 60 relative the second
wedge-shaped grade ring 60 the angle .phi. of one exterior surface
relative to the other may be varied in a range from 0.degree. to
20.degree. in at least one embodiment. The maximum height of the
combined grade rings 60 may also be varied during rotation,
starting with a nominal height, ho. At approximately 90.degree. of
rotation, the overall maximum height is given by equation [3]
hmax=ho+h1 [3]
where h1 is the increased height relative to h0 as shown in FIG.
4b.
[0046] At approximately 180.degree. of rotation, the overall
maximum height is maximized and is given by equation [4]
hmax=h0+h2 [4]
where h2 is the increased height relative to h0 shown in FIG. 4c,
and representing the maximum height increase at 180.degree. of
rotation of the first grade ring 60 relative to the second grade
ring 60.
[0047] Regarding FIG. 5, a grade ring having an alignment flange 66
is schematically illustrated. Situated in alignment flange 66 is an
alignment aperture 68 suitable for use with guide pins (not shown).
The guide pins may be used, in at least one embodiment, to orient
the intermediate grade rings 16 when vertically stacked.
[0048] Turning now to FIG. 6, a retrofit grade ring 70 is
schematically illustrated. In at least one embodiment, retrofit
grade ring 70 may be suitable for a repair of a manhole or a pit.
Non-limiting examples of pits include a restaurant grease
interceptor or a jet fuel pumping pit or a temporary ramp ring used
in road resurfacing. In certain examples, it is desirable not to
have to remove a buried pit when replacing the original manhole
cover. In this exemplary situation, it is useful to place a new
manhole cover above the existing manhole cover in order to affect
better sealing of the pit. However, the replacement manhole cover
now is several inches above the grade of the tarmac. In order to
avoid chipping out cement around the manhole cover, the retrofit
grade ring 70, such as illustrated in FIG. 6, may be applied
directly to the tarmac and secured with fasteners or adhesive. As
illustrated, center opening 72 is defined by the relatively
rectangular annular shell. It is understood that central opening 72
may be of any geometry needed to mate with the manhole cover and is
not limited to having an enclosed annulus.
[0049] FIG. 7 is a cross-sectional view along axis 7-7 of FIG. 6.
FIG. 6 includes a core having more than one density of expanded
polymer bead. In a first density zone 74, the expandable polymer
beads may have a density that is at least one pound per cubic foot
less than the density of expanded polymer beads in the second
density zone 76. It is understood that there may also be a density
gradient exceeding 1 lb/ft3 across the cross-section without a
definitive segmentation into zones.
[0050] Turning now to FIGS. 8a-8e, a method is illustrated for
forming a component of a grade ring system such as a grade ring 16
and/or base grade ring 14. Using blowmolding tooling a paracen 80
is formed as shown in FIG. 8a. Parison 80 defines a cavity 82 and a
longitudinal axis 84 in step 86. Turning now to FIG. 8b, in at
least one embodiment, step 88 includes draw forming of at least one
annular ring shell in a closed mold 90 having at least two portions
92 and 94. During draw forming the mold 90 includes two mold
portions 96 and 98 capable of forming an annular ring.
[0051] Mold portion 92 and 94 are closed about an axis
substantially transverse to the longitudinal axis 84 of parison 80.
In at least another embodiment, mold 90 may include a plurality of
mold portions without exceeding the scope and spirit of the
invention. It is understood that while a annular ring is
illustrated, other geometric shapes may be produced by the same
process. Non-limiting examples of other geometric shapes include a
box frame and a cup having no center opening.
[0052] In step 100 of FIG. 8c, at least one fill port 102 is formed
through mold portion 92 to allow unexpanded polymer beads 104 from
a supply 106 to be fed into a cavity 108 formed by mold portions 96
and 98.
[0053] The heating mechanism, such as steam, is supplied in FIG.
8d, step 120, from steam manifold 122, in at least one embodiment.
The steam is directed to a plurality of steam ports, such as steam
port 124. Spacing between steam injection needles may vary with the
density of unexpanded beads because the steam migration is limited.
In at least one embodiment, the spacing between adjacent steam
injection needles ranges from 1 inch to 6 inches. In another
embodiment, the spacing between adjacent steam injection needles
ranges from 2 inches to 5 inches. In yet another embodiment, the
spacing between adjacent steam needles ranges between the distances
defined by equation [1] and [2].
D 1 = 1 ( ABD .times. 0.56 ) - 0.5 [ 1 ] D 2 = 1 ( ABD .times. 5 )
+ 3 [ 2 ] ##EQU00001##
wherein D1 is the minimum distance in inches between steam
injection needles and D2 is the maximum distance in inches between
steam injection, ABD is on average apparent bulk density of
unexpanded and/or partially expanded polymer particles suitable for
comprising core 44.
[0054] In at least one embodiment, the average apparent bulk
density of the unexpanded and partially polymer particles ranges
from 0.15 lbs/ft3 to 4 lbs/ft3. In another embodiment, the average
apparent bulk density of the unexpanded and partially expanded
polymer particles ranges from 0.2 lbs/ft3 to 2 lbs/ft3.
[0055] Unexpanded expandable beads 104 are expanded by the addition
of steam, such as super-heated steam. Expanded beads 126
substantially fill cavity 108. The annular ring remains constrained
in mold halves 92 and 94 until it is sufficiently cooled to limit
further expansion.
[0056] In at least one embodiment, as shown in step 130 and FIG.
8e, the mold portions 92 and 94 are opened to release the grade
ring component 132 (shown in cross-section). Grade ring component
132 comprises expanded polymer beads and the annular shell 40.
Grade ring component 132 comprises a component of grade ring system
20.
[0057] While exemplary embodiments are described above, it is not
intended that these embodiments describe all possible forms of the
invention. Rather, the words used in the specification are words of
description rather than limitation, and it is understood that
various changes may be made without departing from the spirit and
scope of the invention. Additionally, the features of various
implementing embodiments may be combined to form further
embodiments of the invention.
[0058] While exemplary embodiments are described above, it is not
intended that these embodiments describe all possible forms of the
invention. Rather, the words used in the specification are words of
description rather than limitation, and it is understood that
various changes may be made without departing from the spirit and
scope of the invention. Additionally, the features of various
implementing embodiments may be combined to form further
embodiments of the invention.
* * * * *