Note: Descriptions are shown in the official language in which they were submitted.
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GROUND COVER MATS WITH CROSS BEAM STRAPS
FIELD OF THE INVENTION
The present invention relates to improved ground cover mats.
BACKGROUND OF THE INVENTION
In the oil and gas industry, it is sometimes necessary to provide ground cover
mats with
sufficient strength to support heavy equipment and transport trucks over wet
or disturbed ground.
Several prior art ground cover mats exist; however, they sometimes lack
sufficient reinforcement
to withstand the pressure of heavy equipment and transport trucks, and are
expensive to produce.
What is needed is an improved ground cover mat which is simple and relatively
inexpensive and
has sufficient strength and durability to support heavy equipment.
Further, ground cover mats tend to be extremely heavy and lengthy, making the
mats difficult to =
store, lift, transport, assemble or disassemble. Since a series of mats are
generally required to
construct a temporary road, an improved ground cover mat which is easy to
handle is desirable.
There have been attempts in the prior art to solve such problems. For example,
United States
Patent No. 4,462,712 issued July 31, 1984 to Penland, Sr. describes an
interlocking mat assembly
comprising assemblies of two-ply laminated mats which interlock and are
secured together by
nailing a top layer of planks over the interlocked mats. However, this mat
assembly is
particularly labor intensive.
Canadian Patent No. 1,285,166 issued June 25, 1991 to Pouyer describes a
temporary road which
includes a plurality of sets, each defined by upper and lower matrices with
the upper matrices
comprising boards and the lower matrices comprising cross-support members for
supporting the
boards. The road is constructed by interlocking series of sets in a
superimposed assembly,
necessitating significant redundancy of effort in assembly and disassembly.
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United States Patent No. 6,695,527 issued February 24, 2004 to Seaux et al.
describes
interlocking mats constructed of two mirror half pieces which are joined
together to form a
complete single mat containing an internal cellular structure. Traction
promoting elements in the
form of raised strips extending outward from the planar surfaces of the mats
and aligned with the
internal cell forming walls are provided to improve traction and to absorb
heavy loading from
vehicles and equipment. However, Seaux et al. indicates that when a large
number of the raised
strips are not specifically positioned in such a manner, the relatively thin
outer skin defining the
roughly planar surfaces of the mats can become easily deformed by such direct
loading.
United States Patent Nos. 4,600,336 and 5,087,149 issued July 15, 1986 and
February 11, 1992
respectively, to Waller describe mat systems having individual mats with
alternating offset
extensions and recesses along the edges. These systems are disadvantageous in
that the offset
extensions are comprised of individual planks which may be subject to warping
or splintering
when exposed to heavy loads. Further, the offset extensions need to be nailed
in place to be
secured within the recess of an adjacent mat. An extra plank is secured over
the exposed nailed
joints of adjacent mats to interlock the mat assemblies together as a roadway,
which significantly
increases material and labor requirements.
Canadian Patent No. 2,348,328 issued October 22, 2002 to Stasiewich et al
describes a road mat
including, at both of its ends, couplings having retaining lips which engage
complimentary
retaining lips of adjacent mats to prevent separation when weight applied by a
vehicle to one
road mat is transferred to an adjacent road mat, Canadian Patent No. 2,364,968
issued June 22,
2004 to Stasiewich et al describes a road mat having end and side interlocks
to secure adjacent
mats. However, there is no provision in either patent of details regarding
attachment of the
retaining lips to the mat ends, or the use of any reinforcing structural
support.
The present invention addresses the above shortcomings of the prior art,
meeting the need for an
improved ground cover mat which has sufficient strength to support heavy
equipment, provides
easy handling, and is simple and relatively inexpensive.
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SUMMARY OF THE INVENTION
The present invention is directed to ground cover mats. In one aspect of the
invention, the
invention comprises a ground cover mat comprising:
(a) a quadrilateral frame comprised of:
(i) two substantially parallel opposing end members; and
(ii) two substantially parallel outside longitudinal members,
each having an
inner channel;
(b) two opposing major surfaces formed from a plurality of elongate boards
retained
within the frame, wherein at least one major surface defines a transverse
groove
substantially parallel to the end members; and
(c) at least one cross beam strap disposed within the transverse groove,
wherein each
end of the strap is disposed within a longitudinal member inner channel, and
wherein the strap is substantially flush with a major surface of the mat.
In one embodiment, the mat comprises a third longitudinal member comprising an
I-beam mid
rail which is parallel to the two outside longitudinal members and attaches to
the end members,
substantially bisecting the mat. Where a mid rail is used, the cross beam
straps attach to the
outside longitudinal member and the mid rail.
In one embodiment, cross strap beams are provided on each opposing major
surface. The cross
strap beams may be aligned with each other and a pin used to attach the two
straps to each other.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described by way of an exemplary embodiment with
reference
to the accompanying simplified, diagrammatic, not-to-scale drawings.
Figure 1 is a diagrammatic representation of a mat of one embodiment of the
present
invention.
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Figure 2 is a cross-sectional view of a mat, along line II-II in Figure 1.
Figures 3A and 3B are detailed views of portions of Figure 2.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides for reinforced ground cover mats. When
describing the present
invention, all terms not defined herein have their common art-recognized
meanings. To the
extent that the following description is of a specific embodiment or a
particular use of the
invention, it is intended to be illustrative only, and not limiting of the
claimed invention. The
following description is intended to cover all alternatives, modifications and
equivalents that are
included in the spirit and scope of the invention, as defined in the appended
claims.
The invention will now be described having regard to the accompanying Figures.
The mat (10)
is comprised of a quadrilateral frame (12), and planar surfaces formed from a
plurality of
elongate boards (14), A suitable mat is described in Applicant's co-owned US
Patent No.
7,934,885, the entire contents of which are incorporated herein by reference,
where permitted,
The quadrilateral frame (12) comprises two substantially parallel opposing end
members (18)
and two substantially parallel outside longitudinal members (20). Each end
member (18) has an
inner slot (24) facing the opposing end member (18). Each longitudinal member
(20) has a slot
(not shown) facing the opposing longitudinal member (20).
The elongate boards (14) are retained within the frame (12). The mat (14)
forms two opposing
major surfaces (28). The mat boards (14) insert into, and are retained by the
inner slots (24) of
the end members (18).
In one embodiment, each board (14) has a substantially rectangular cross-
section and is disposed
such that the vertical dimension of the board (14) is larger than the
horizontal dimension, thus
increasing the bending strength of the mat (10). The boards may be glued
together and staggered
to increase the strength of the mat. The boards (14) may be single 2x4 or 2x6
boards or may be
constructed using wood layers bonded to composite material layers.
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In one embodiment, the board comprises at least one wood layer bonded to at
least one
composite material layer. As used herein, the term "composite" refers to any
engineered material
made from two or more constituent materials with significantly different
physical or chemical
properties and which remain separate and distinct on a macroscopic level
within the finished
structure. In one embodiment, the composite material layers may comprise
fiberglass; however,
such other materials as are commonly used in the art may also be employed for
the boards (14).
The frame (12) is constructed from any suitable material such as steel. In one
embodiment, the
frame (12) may comprises a third longitudinal member comprising a mid rail
(32) which is
connected at each end to the midpoint of each end member (18) in an
orientation that is
substantially parallel to each longitudinal member (20). In one embodiment,
the mid rail (32) is
an I-beam, thereby having slots (34) facing the longitudinal members (20). The
boards (14)
insert into, and are retained by the slots (34) on the mid rail (32).
A plurality of cross beam straps (36) are arranged in an orientation that is
substantially parallel to
the opposing end members (18). Each cross-beam strap (36) comprises a flat
metal bar, and is
connected at one end to the mid rail (32) and at the other end to a
longitudinal member (20). In
the prior art, cross beam straps are used but are butt-welded to the
longitudinal members and the
mid rail, such that it is disposed on top of the boards (14) and flush with
the longitudinal
members and mid rail. In the present invention, the applicant has found that
by modifying the
installation of the cross beam strap, significantly better results may be
obtained.
As shown in Figure 2, a transverse groove is cut into the boards (14) having a
depth
approximately equal to the thickness of the cross beam strap (36). The strap
(36) is lengthened
slightly such that the ends overlap and slide under the longitudinal member
channel on one side,
and within the mid rail I-beam channel on the other side. The strap is then
lap welded into place,
as shown in Figures 3A and 3B. In an embodiment where no mid rail is in place,
the cross beam
strap will extend across the entire mat and be affixed to both longitudinal
members.
Accordingly, the strength of the weld attaching the cross beam strap is much
stronger, and even
if the weld breaks, the strap is still held in place within the transverse
groove, and by the ends
which are tucked under the longitudinal members and the mid rail.
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In one embodiment, cross beam straps (36) are aligned on either side of the
mat, and held
together by a pin (38) which is welded in place.
The number and spacing of the cross-beam straps may vary according to the size
and
construction of the mat. As shown in Figure 1, an exemplary mat that is about
40 feet long and
which is bisected by a mid rail, has 10 cross beam straps on each side, 20 in
total, spaced in an
equidistant manner between the two end members (18).
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