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This is a continuation-in-part of PCT/CA92/00509, filed Nov. 16, 1992.
FIELD OF INVENTION
The present invention relates to a novel structure which functions as a
transition collar for catch basins and manholes.
BACKGROUND TO THE INVENTION
At the present time, asphalt paving material generally surrounds manholes
and catch basins. However, optimum compaction of the asphalt adjacent the
periphery of the manhole or catch basin leads to deterioration of the
asphalt in use. Expansion and contraction of the pavement occurs with
varying temperature and leads to asphalt break-up, cracking and separation
between pavement and manhole. Repairs typically are required at least
every two to three years.
A search of the prior art conducted in the U.S. Patent and Trademark Office
has located the following U.S. patents as the most relevant prior art:
______________________________________
3,263,580 4,808,025
4,927,290 5,030,030
4,759,656 4,925,336
4,969,771 FR2303122
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With respect to the prior art, U.S. Pat. Nos. 5,030,030 and 4,925,336
contain the same disclosure. These references describe a pad which
supports a utility access conduit in a roadway. The support pad comprises
a rectangular block of rubber or similar compressibly resilient
elastomeric material which has an opening through it to snugly engage the
access conduit.
U.S. Pat. No. 3,263,580 discloses a safety cover for a manhole which
overlies the manhole cover, sits flush with a roadway and is fastened to
the manhole cover by bolts. The cover also surrounds the upper portion of
the manhole structure at the periphery.
French Patent No. 2,030,122 describes a procedure for fixing the frame of a
manhole cover in place. A ring-shaped rebate is formed surrounding the
frame and a sealant comprising a hardenable resin material is passed into
the rebate and hardened to provide the final structure.
It will be apparent from the discussion below that none of this prior art
discloses or suggests the structures which are described herein.
SUMMARY OF INVENTION
In accordance with the present invention, there is provided a novel
structure which is intended to overcome these prior art problems. The
present invention provides a resilient annular collar for the manhole or
catch basin, which acts as a flexible transition between the rigid
structure or frame of the manhole and the semi-rigid structure of the
asphalt paving. The present invention also provides an improved mold
structure for the provision of such collars.
Accordingly, in one aspect, the present invention provides a roadway
structure comprising a subterranean access opening in said roadway, a
self-supporting rigid frame structure surrounding said opening, a roadway
pavement structure having a depression therein surrounding said
subterranean opening and wherein is located said self-supporting rigid
frame structure, and a resilient transition collar structure received in
said depression and surrounding said rigid frame structure and spacing the
distance from said rigid frame structure to said roadway pavement
structure, said roadway depression being dimensioned and said resilient
collar structure being arranged such that the upper surface of the
transition collar structure lies in substantially planar alignment with
the upper surface of said roadway pavement structure.
In another aspect of the present invention, there is provided for use in a
roadway construction, the combination of (a) an annular
resiliently-flexible transition collar having a central opening formed
therethrough for receiving a self-supporting rigid frame structure of a
roadway subterranean access opening therein, and (b) a set of riser rings
for adjusting the height and/or orientation of said transition collar in a
roadway depression adjacent the subterranean access. The present invention
also includes riser rings for this purpose.
A further aspect of the invention provides an injection mold for molding a
resilient transition collar from rubber scrap from automobile tires,
comprising a mold cavity corresponding in shape to that of the collar into
which rubber scrap is introduced to effect such molding, and defined by
upper and lower mold-forming elements, one of said upper and lower
mold-forming elements having heat-transfer studs protruding therefrom into
the mold cavity.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a plan view of a road structure incorporating a novel resilient
collar constructed in accordance with one embodiment of the invention;
FIG. 2 is a side elevational sectional view of the road structure of FIG.
1;
FIG. 3 is a sectional view of a mold structure employed to form transition
collars according to one embodiment of the invention;
FIG. 4 is a plan view of the mold structure of FIG. 3;
FIG. 5 is an exploded perspective view of the road structure shown in FIGS.
1 and 2 illustrating the relationship of the frame, transition collar and
riser elements;
FIG. 6 is an exploded perspective view of an alternative form of roadway
access device incorporating the present invention;
FIGS. 7, 8 and 9 are sectional views of three different riser elements used
in conjunction with the resilient annular collar.
GENERAL DESCRIPTION OF INVENTION
The resilient transition collar provided herein absorbs any movement of the
pavement during expansion and contraction and this absorption avoids the
prior art problems of break-up, cracking and separation between manhole
and pavement. The resilient transition collar also absorbs shock and
traffic vibration damage to the road surface and to the maintenance
opening (manhole) and catch basin substructure as well as minimizing
damage due to earth tremors or soil movements.
The resilient collar, which usually is formed of rubber material or other
resilient material, which may be cured recycled scrap from automobile
tires, has a relatively long life expectancy, such as twenty years or
more, so that, once installed, the resilient collar avoids the necessity
for the frequent repairs currently required.
The resilient collar permits better compaction of the asphalt adjacent the
manhole or catch basin during paving operation as well as a simplified
paving operation. Poor compaction of asphalt is often the reason for
deterioration of the asphalt in the region of the manhole or catch basin.
In addition, repair or replacement of the resilient collar is quicker and
less labour intensive than the prior art.
The rigid frame of the manhole or catch basin, which generally supports a
closure or cover, generally is round but may take other geometric shapes,
such as square. The resilient collar has a central opening which is shaped
to correspond to the shape of the cover, so as to snugly fit against the
periphery of the frame structure. Generally, the collar has a thickness
corresponding to the depth of the cover.
Minor adjustments with respect to differences in depth and orientation of
the opening into which the transition collar is inserted and the pavement
surface may be effected to ensure a flush fit between the pavement surface
and the upper surface of the transition collar.
These adjustments may be effected by using risers or adjusting rings, also
formed of resilient elastomeric material, such as scrap rubber, positioned
below the transition collar in the roadway opening. The adjusting rings
are annular and may be of the same external dimensions as the transition
collar and have a central opening which does not interfere with sealing of
the frame in the roadway opening.
The risers or adjusting rings preferably comprise a set of three such
rings, two having a uniform thickness but which differs one from the
other, for example, three inches and two inches thickness. Sectional views
of a set of such riser rings are shown in FIGS. 7, 8 and 9. The third
riser has a wedge shape in side elevation view, varying uniformly from a
first thickness dimension at one side to a second thickness dimension at
the other, for example, 0.25 inch at one side and 0.5 inch at the other
side. Members of the set and multiples thereof may be employed to provide
for the correct height adjustment.
The uniform thickness risers permit adjustments to be made to compensate
for variations in depth of the roadway opening while the non-uniform
thickness risers permits adjustments to be made to compensate for a
sloping bottom surface of the roadway opening. The risers may be combined,
as necessary, in a particular manhole or catch basin situation.
The risers may be formed by compression molding of scrap rubber or other
elastomeric material so as to be resiliently flexible, as described below
to the desired combination of properties.
The resilient collar as well as the risers may have any convenient
peripheral outline. Preferably, the collar has a circular outline to
provide for an even distribution of forces applied to the transition
collar in use, but any other convenient shape may be employed, such as
square, particularly when employed with square or rectangular catch basin
openings.
The novel road structure provided herein, comprising a manhole or catch
basin, and resilient collar surrounding the manhole or catch basin and
spacing a gap to the asphalt pavement, constitutes a considerable
improvement over the prior art, having regard to the advantages thereof.
Considerable long term economies can be realized employing the resilient
collar arrangement of this invention.
The rigid frame of the manhole or catch basin may be permanently embedded
in the collar, such as by molding the collar about the rigid frame, which
often is formed of cast iron, before positioning the transition
collar-rigid frame unit in the roadway or other location of the
maintenance opening or catch basin, with or without riser rings. This
arrangement ensures a secure bond between the transition collar and the
rigid frame.
The manufacturing mold used for such molding operations may be designed to
accommodate a variety of different size and configuration of frames while
maintaining the same external dimension of transition collar.
The compression molding operation forming the transition collar preferably
effects compression molding of rubber from scrap automobile tires or other
scrap rubber material, together with the frame, to a desired density,
modulus of elasticity, thermal expansion and hardness for the molded
collar.
By employing scrap rubber material in the manufacture of the transition
collar and risers, recycle of such waste material into a useful product is
achieved. The transition collar and risers do not generate waste, since
damaged or discarded collars and risers can themselves be recycled and
fully used in the production of new collars and risers.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring first to FIGS. 1 and 2 of the drawings, a road structure 10
comprises a catch basin or manhole structure 12, a cast iron frame 13 and
cover or access hatch 14 for the catch basin or manhole structure 12 and
having a circular periphery, a resiliently flexible rubber transition
collar 16 surrounding the frame 13 and in engagement with the outer
periphery thereof, and an asphalt pavement 18 surrounding and in
engagement with the outer periphery of the collar 16.
The transition collar 16 sits flush with the asphalt pavement 18 in a
generally circular opening therein. To compensate for variations in the
depth and orientation of the subsurface on which the transition collar 16
sits, risers of the type described above may be employed (see FIGS. 5 and
6).
As seen in FIG. 5, one or more riser rings 20 may be positioned on the
roadway depression and support the cast iron frame 13, providing such
height adjustment as may be required to provide the transition collar
flush with the asphalt pavement 18.
FIG. 6 shows an alternative form of transition collar 16', in this
embodiment, in square outline for use with a rectangular catch basin cover
or access hatch 14'. The collar 16' surrounds the rectangular frame 13'
and is provided in engagement with the outer periphery thereof. The riser
rings 20' are provided in rectangular shape to coincide with the shape of
the frame 13'.
Referring now to FIGS. 3 and 4, there is illustrated therein a mold
structure 50 which is useful for forming the transition collars 16 by
compression molding. As may be seen therein, the mold structure 50
comprises an upper mold element 52 and a lower mold element 54, which
cooperate to define a mold cavity 56 in which the collars are molded. The
mold cavity 56 is provided with an inlet 58 for feeding the granular
rubber crumb from which the transition collar is molded.
The transition collar 16 is molded to the manhole frame structure 60
positioned in the mold 50 and providing the inner wall of the mold, so
that an integral unit is provided for positioning in the roadway
depression. The upper mold element 52 is provided with a series of studs
62 which project downwardly into the mold cavity 56. The studs 62 are
arranged in a uniform array, as seen in FIG. 4. However, the number and
size of such studs 62 is dependent on the mold and product design.
The studs 62 provide improved heat transfer to the transition collar 16
during the curing cycle, than in the absence of such studs, resulting in
decreased curing time and an increased production rate of the collars.
SUMMARY OF DISCLOSURE
In summary of this disclosure, the present invention provides a novel
resilient collar structure useful for providing an improved road
structure, as described in detail above, as well as an improved mold
structure to produce such collars. Modifications are possible within the
scope of this invention.
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