Note: Descriptions are shown in the official language in which they were submitted.
CA 02400873 2002-08-29
Attorney Docket No. 034913-48-6001
RESILIENT PEDESTAL HEAD FOR
A RAISED ACCESS FLOOR SYSTEM
Field of the Invention
This invention is directed generally to raised access floors having a
plurality of
individual floor panels supported by pedestals and, more particularly, to a
resilient
pedestal head fox supporting the floor panels.
Description Of Related Art
Raised access floors are widely used in commercial and industrial buildings
where communication lines, air ducts, and other utilities are frequently
altered or
supplemented. These floors are a convenient way to hide utilities while
offering easy
access as needed. Raised access floors typically include a plurality of floor
panels
supported by a series of pedestals, which are typically arranged in a grid or
matrix
arrangement. The base of the pedestal attaches or rests on a subfloor. The
floor panels
are readily removable from the installed access floor and can be
interchangeable with
1S other floor panels. The pedestals can be adjustable to vary the finished
floor height, and
each pedestal usually includes a pedestal head. The floor panels are secured
to or simply
rest on the pedestal heads.
It is important that raised access floors be level and the individual panels
aligned.
Unlevel access floors and misaligned panels can result in difficulties in
moving
~ equipment over the raised floor due to differences in height between
adjacent panels or
gaps between panels. AdditionaIly,'deflection of a floor panel subject to a
heavy load
may cause the floor to be uneven, further complicating the movement of
equipment over
or storage of equipment on the floor. Furthermore, misaligned panels can
result in
inefficiencies in under-floor heating, ventilation, and air conditioning
(HVAG) systems,
and, of course, are not aesthetically pleasing in appearance. .~
By their very nature - being modular and individually removable - individual
panels can become displaced out of the level plane of the floor, that is,
panel edges can
become misaligned creating gaps or variations across the floor. This can be a
problem
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both during installation and use. As discussed above, floor panels can be
secured to
pedestal heads or can simply rest on the pedestal heads. Panels that can be
secured
typically include a hole in each corner that penetrates the entire floor
panel. One type of
conventional pedestal head includes a square, flat plate that generally
includes four holes
to receive fastening elements, such as bolts, to secure the corners of four
floor panels to
the pedestal head. Installing such floor systems requires manually aligning
the holes in
floor panels with holes in the flat plate pedestal head. However, when
securing the floor
panel to the conventional flat-plate pedestal head, differences in dimensions
due to
typical manufacturing tolerances often cause the bolts to be disposed in an
oblique
position with respect to an axis perpendicular to the subfloor. Because these
conventional flat-plate pedestal heads are rigid, the differences in
dimensions produced
by manufacturing tolerances often results in gaps and misalignment of the
edges of
adjacent floor panels, which can produce an uneven floor surface. In general,
installers
utilize tools, such as hammers to apply external forces to attempt to bend,
i.e., plastically
deform, the pedestal head and/or the fastening elements until adjacent floor
panels are
level and aligned. However, the rigidity of the pedestal heads themselves
hinders
attempts to align misaligned floor panels.
Another conventional pedestal head - the dual-level pedestal head - attempts
to
address the problem of imprecisions inherent in aligning floor panels that are
secured to
flat-plate pedestal heads. The conventional dual-level pedestal head generally
includes
. an elevated bracket attached to the top surface of a square flat plate, thus
dividing the
square plate into four separate quadrants. This design permits an installer to
slide or
place the' comers of the floor panels against the elevated bracket, which is
an attempt to
minimize the amount of manual alignment required bjr the installer. A further
refinement to this conventional design includes raised elements on the lower,
or flat- .
plate, portion of the dual-level pedestal head adapted to engage a
corresponding recess or
mating surface on the lower surface of the floor panels. Such refinements are
often
described as positive positioning or locking devices. While these types of
features may
help reduce the imprecisions inherent in manually aligning holes in the floor
panels with
holes in the pedestal head, such conventional pedestal heads still do not
overcome all of
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the problems of misaligned floor panels due to imprecisions in manufacturing
the floor
panels and the holes therein, and the like. Moreover, it is believed that the
elevated
brackets attached to the top surface of the flat plate in the dual-level
pedestal head design
increase the rigidity of an already rigid flat plate. Thus, it is believed
that this additional
rigidity further compounds misalignment caused by manufacturing imprecisions
as well
as frustrates attempts by installers to manually manipulate the floor panels
into alignment
by deforming the pedestal head and/or the fastening elements.
A related problem with conventional, rigid pedestal heads of both flat and
dual
level designs is their propensity to plastically deform under certain loading
conditions,
which give rise to misalignment of the attached panels during use.
Conventional
pedestal heads generally support a small portion - typically the corners of
the floor
panels - of the lower surface of the floor panels. Loads that are applied to
the corner of
the floor panels act in direction substantially along the axial length of the
pedestal, and
are thus, resisted by the pedestal itself. However, Ioads that are applied
away from the
corners of the floor panels, e.g., near the middle of the floor panel, create
large moments
about the pedestal. These loads are resisted by the ability of the pedestal
head to resist
moments. It is believed that heavy loads applied away from the pedestal can
cause the
pedestal head to deform permanently. Thus, even conventional access floors
that have
been properly aligned when installed, may become misaligned following
application of a
heavy load to the floor panels. Because conventional pedestal heads are rigid
and
permanently deform under such loads, the pedestal heads and attached floor do
riot
realign if the load is removed.
Floor panels that have carpeting or laminate applied to their outer surface
lack a
hole in each corner. Instead of being secured to the pedestal head, such floor
panels
merely rest on the pedestal head. These floor panels usually do not experience
the
misalignment duiing installation as do floor panels that are secured to the
pedestal heads.
During use, however, unsecured floor panels can be susceptible to
misalignment, just as
the secured floors described above. But as unsecured floor panels are less
rigid than
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secured floor panels, unsecured floor panels can become misaligned at loads
lower than
those required to deform and misalign secured floor panels.
The foregoing demonstrates that known raised access floors suffer from a
number
of disadvantages including pedestal heads that do not compensate for
manufacturing
tolerances of floor panels and/or permanently deform after a load is applied
to the floor
panel, such that there is a resulting mismatch of.the edges and/or top
surfaces of adj scent
floor panels.
Summary Of The Invention
The invention solves the problems and avoids the disadvantages of the prior
art
by providing a pedestal head that is sufficiently resilient to allow for
alignment of the
floor panels during installation of the floor panels and to allow individual
access floor
panels to maintain their originally-aligned position after having been
subjected to a
heavy load during use. In particular, the invention accomplishes this by
providing a
resilient pedestal head for use in supporting floor panels of an elevated
flooring system.
The resilient pedestal head includes a base and an arm extending from and
supported by
the base for cantilevered movement relative thereto. The base has a first
surface,
disposed in a first plane, configured to support a first portion of a corner
of a floor panel.
The arm has a second surface configured to support a second portion of the
corner of the
floor panel. The second surface is disposed in a second plane generally
parallel to the
' first plane in a first configuration of the pedestal head. The arm is
deflectable by the
weight of a panel mounted thereon to define a second configuration in which
the second
surface is nonparallel to the first plane. The base may also include
additional arms for
supporting additional floor panels. Each arm extends from and is supported by
the base
for cantilevered movement relative thereto. Each arm also has a surface
disposed in the
second plane for supporting another floor panel. In a preferred embodiment,
four arms
are provided, two on each side of the base, to support the corners of four
panels. The
arms on each side of the base may define, with the base, a generally u-shaped
cross-
section for supporting the panels mounted on the rear in a substantially
level, aligned
position regardless of the differences in dimensions caused by variations in
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manufacturing tolerances. Each arm may have an L-shaped cross sectional shape
defined as a downwardly extending projection and a flange, generally
perpendicular
thereto.' The distance between adjacent projections ofthe arms on each side of
the base
may vary to bias the arms into a position capable of providing restoring
moments tending
to offset deflections of the panels mounted on the arms due to manufacturing
tolerances.
According to another aspect of the invention, an elevated floor system is
provided
for supporting access floor panels, which includes first and second panels
each having a
comer and a pedestal having a head for supporting first and second panels. The
pedestal
includes a base having a first mounting surface supporting first portions of
the corners of
the first and second floor panels. The base also has first and second
cantilevers
extending therefrom. Each cantilever has a second mounting surface vertically
spaced
from the first surface and supporting a second portion of the corner of one of
the first and
second floor panels. The first and second mounting surfaces are disposed in
substantially parallel planes prior to mounting the panels thereon. The first
and second
cantilevers are deflectable relative to the base under the weight of the first
and second
panels mounted thereon to define a second configuration in which the first and
second
surfaces are nonparallel. The second mounting surface of each cantilever may
include a
first hole and the first and second floor panels each may include a second
hole. The first
and second holes may be aligned to receive a fastener when one of the floor
panels is.
2Q ' mounted to one of the arms such, that connection of the panels to the
arms by fasteners
. force the arms to deflect into the second configuration due to dimensional
variations
between the panels and the head caused by manufacturing tolerances.
In yet another aspect of the invention, a method of installing an elevated
floor
system composed of floor panels supported on a subfloor by pedestals having a
pedestal
head for supporting upper and lower portions of each floor panel on first and
second
vertically spaced mounting surfaces of the pedestal head is provided. The
method
includes the steps of a) disposing the upper portion of a first panel on the
first mounting
surface of a pedestal head and the lower portion of the first panel on a
portion of the
second mounting surface of the pedestal head; b) connecting the first floor
panel to the
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second mounting surface of the pedestal head; c) disposing the upper portion
of a second
panel on the first mounting surface of the pedestal head and the lower portion
of the
second panel on another portion of the second surface of the pedestal head;
and d)
connecting the second floor panel to the second mounting surface of the
pedestal head
S , such that the panels create moments deforming the pedestal head to a
position in which
the first and second panels are non-parallel to each other. In addition the
pedestal head
may be plastically deformed to align the first and second panels ~in a level
plane by
applying a force in a region of the connected floor panels proximate the
pedestal head, or
applying a force to at least one of the first and second panels at a location
spaced from
the pedestal head. The connecting steps may include the steps of aligning a
hole in the
first floor panel with a first hole in the second surface of the pedestal
head, and aligning
a hole in the second floor panel with a second hole in the second surface of
the pedestal
head.
Additional features, advantages, and embodiments of the invention may be set
forth or apparent from consideration of the following detailed description,
drawings, and
claims. It is to be understood that the foregoing summary of the invention and
the
following detailed description are exemplary and intended to provide further
explanation
without limiting the scope of the invention as claimed.
Brief Descriptions Of The Drawings
' The accompanying drawings, which are incorporated herein and constihzte part
of
this specification, illustrate preferred embodiments of the invention, and,
together with
the detailed description below, serve to explain the principles of the
invention.
In the Drawings:
Figure 1 is a perspective view of a raised access floor structure with one
panel
removed to partially expose several resilient pedestal heads constructed
according to the
principles of the invention.
Figure 2 is a perspective view of a pedestal that may be used to support. the
resilient pedestal head of the invention.
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Figure 3 is an enlarged perspective view of one of the resilient pedestal
heads of
the invention shown in Figure 1.
Figures 4A and 4B are plan and partial cross sectional views, respectively,
o'f the
pedestal head shown in Figure 3, with Figure 4B being taken along lines B-B of
Figure
S 4A. Figure S is a plan view of a template for forming the pedestal head
shown in Figure
3.
Figure 6 is a partial perspective view of a floor panel that may be used with
the
pedestal of the invention.
Figure 7 is a perspective view of a pedestal, pedestal head and partially-
installed
access floor constructed according to the invention.
Figures 8A - 8C are cross sectional views of the resilient pedestal head of
the
invention with attached floor panels showing three different positions the
assembly may
take based upon variations in dimensions produced during manufacture.
Figure 9 is a perspective view of second embodiment of a resilient pedestal
head
1 S constructed according to the principles of the invention.
Figures 10A and 10B are plan and partial cross sectional views, respectively,
of
the pedestal head shown in Figure 9, with Figure lOB being taken along lines B-
B of
Figure 10A.
Figure 11 is a plan view of a template for forming the pedestal head shown in
Figure 9.
Detailed Description Of The Preferred Embodiments
4 Reference will now be made in detail to preferred embodiments of the
invention,
examples of which are illustrated in the accompanying drawings. Figure 1 shows
a
perspective view of part of a raised access floor system 10 constructed in
accordance
2S with a preferred embodiment of the invention. As shown in Figure 1, the
raised access
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floor system 10 is installed on a subfloor 20 and generally includes floor
supports such as
pedestals 30 having resilient pedestal heads 40 used to support floor panels
S0.
Typically the pedestals 30 are arranged in a grid-like pattern with
pedesta1s,30
spaced substantially equidistant from one another. The height of pedestals 30
may be
S adjustable as is known in the art. The pedestals 30 support the corners of
the floor panels
50, thus forming the raised floor system 10. Each one of the pedestals 30 that
is located .
in middle portions of the raised floor system 10 supports corners of four of
the floor
panels 50. Each one of the pedestals 30 that is located along edge portions of
the raised
floor system 10 supports corners of two of the floor panels 50, while each one
of the
IO pedestals 30 located at an end portion of the raised floor system 10
supports a corner of
one of the floor panels S0. The panels 50 may rest on or be attached to
pedestal heads
40, and each one of the floor panels 50 is individually removable to provide
access to the
subfloor 20 located beneath the raised flooring.
Pedestal 30 is preferably an adjustable pedestal of the type, for example,
shown
1 S in Figure 2. However, any conventional type of pedestal may be used in
accordance with
the principles of the invention. The pedestal 30 in Figure 2 generally
includes a base 32,
a post 34, a rod 36, and an adjusting device 38. The base 32 is shown as being
generally
square-shaped but can be a variety of other geometric shapes, including
circular or
rectangular, and the corners of the base 32 may be rounded as shown in Figure
2. The
20 ~~ base 32 may be a substantially flat plate. Alternatively, the base 32
can include raised or
web-like portions, which are believed to impart greater structural strength
and rigidity
than a substantially flat plate. The base 32 can rest on or be secured to the
subfloor 20,
as is known in the art. If the base 32 is to be secured to the subfloor 20, a
plurality of
anchor holes 33 may be disposed in the base 32. The anchor holes 33 may be
adapted to
25 accept conventional anchor devices, including concrete expansion anchors.
Alternatively, the base 32 may be secured to the subfloor 20 by an adhesive or
any other
method or means known in the art.
The post 34 is coupled rigidly to the base 32 and extends substantially
perpendicularly therefrom. The post 34 has a lower end 34a attached to
the.base 32 and
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an upper end 34b adapted to receive the rod 36. The cross-section of the post
34 can be a
variety of geometric shapes, including circular, rectangular, or square, but
as shown in
the figures, the cross-section of the post is square. The corners of post 34
may be square,
beveled or rounded. The post 34 and the base 32 may be .formed separately or
as a'
unitary whole. If the post 34 and the base 32 are formed separately, the lower
end 34a
of the post 34 may be fixedly connected to the base 32 by at least one weld
35.
Alternatively, the lower end 34a of the post 34 may be connected to the base
32 by'
providing the base 32 with a raised threaded portion (not shown) and the lower
end 34a
of the post 34 with a complementary surface (not shown) adapted to engage the
threaded
portion of the base 32. Again, any other means known in the art for making or
.
connecting the base and post together to form the pedestal may be employed.
If an adjustable height pedestal is employed, the rod 36 may be coupled to the
upper end 34b of the post 34 in any number of ways known in the art to provide
a
lockable, variable height between subfloor 20 and floor panels 50. For
example, in the
I5 ' illustrated embodiment, the rod 36 is slidably received within the upper
end 34b of the
post 34. The outer surface of the rod 36 may be threaded along the entire
axial length or
a sufficient portion of the axial length of the rod 36 to engage the inner
surface of an
adjusting device 38, such as nut 38 described below, which sits on top of post
34 and
receives the lower end of the rod 36. By virtue of the engagement between the
rod 36
and nut 38, rod 36 telescopes within the post. Thus, the height of the
pedestal 30 can be
adjusted by rotating nut 38, which varies the position of the rod 36 with
respect to the
post 34. Once a desired height of the pedestal 30 is obtained, the position of
the rod 36
with respect to the post 34 is fixedly secured in a predetermined position by
a locking
projection that extends from the threaded surface on the endv of the rod 36
and'prevents
~ rod 36 from rotating within post 34.
As shown in Figure 2, nut 38 may include one or more axial projections 38a.
The
axial projections 38a extend from the top and bottom opposing faces of nut 38
(only the
top face is shown in Fig. 2). Two axial projections 38a are provided to allow
either end
of the adjusting device 38 to be threaded onto the rod 36, but only one is
required to
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prevent rotation of nut 38. Nut 38 may be threaded onto bottom end of rod 36
if the top
end is already connected to the pedestal head 40 (as shown in Figure 3) into a
desired
position along the length of the threads. If rod 36 and pedestal head 40 are
not yet
connected, nut 38 may be threaded onto top end of rod 36. When the nut 38 is
seated on
the top surface of the upper end 34b of the post 34, the bottom projection 38a
of nut 38
prevents rotation of the nut relative to post 34. Furthermore, the weight of
the installed
floor panels 50 upon the pedestal head supported by the post 36 (Figure 3)
provides
additional compressive loads that act to fully seat the nut on the post 34;
thus preventing
rotation of nut 3 8 in use.
Any other adjustable or non-adjustable pedestal known in the art may be used
with the resilient pedestal head of the,invention. For example, the adjusting
device 38
can be a seating-Iock type, a spring stop-nut type, a prevailing torque type,
a wedge type,
or a quick-release type. In addition, the inner surface of post 34 may be
threaded to
engage directly the threads on rod 36 and a conventional set screw threadably
received
1 S in a side of post 34 may be used to lock the in position with respect to
post 34.
Referring to Figures 3, 4A, and 4B, a resilient pedestal head 40 made in
accordance with the principles of the invention is shown. As shown in Figure
3, the
pedestal head 40 is fixedly connected to the rod 36 of the pedestal 30 by any
means.
known in the art, such as welding or by providing the pedestal head 40 with a
v complementary surface (not shown) adapted to engage the threaded surface of
the rod 36.
Thus, as described above, the position or height of the pedestal head 40
relative to the
subfloor 20 changes when the height of rod 36 is adjusted within post 34 by
nut 38.
Pedestal head 40 generally includes a top plate 42 having four L-shaped arms
formed by
downwardly depending projections 46 and flanges 44 outwardly' extending
therefrom in
a cantilevered fashion for supporting floor panels 50. As the top plate 42
also is adapted
to support one or more floor panels 50 in a manner discussed herein, the top
(uppermost)
surface of the top plate 42 will typically be substantially flat as
illustrated: Thus, the top
surface of the top plate 42 lies in a plane substantially horizontal and
substantially
transverse to vertical axis A shown in Figure 4B. .Extending outwardly from
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of the top plate 42 are four extensions 42a, each of which preferably have
substantially
the same length and such that the top surface of plate 42 has a generally
cross-shape.
The extensions 42a form corner regions 42b on the top surface to receive a
corner of a
panel 50. Only two of the four extensions 42a include the projections 46 and
panel
supporting flanges 44. The other two of the extensions 42a include downwardly
depending skirts 42c to strengthen top plate 42. The top plate 42 may include
a number
of holes 42d formed in extensions 42a for manipulating and aligning the
pedestal head
40 during manufacture, e.g. during the stamping and forming process described
below.
The projections 46 depend downwardly from two opposed extensions 42a such that
the
flanges 44 of each L-shaped arm are spaced from and substantially parallel to
the surface
of the top plate 42. Flanges 44 may have substantially the same length and axe
adapted
to support a corner portion of the floor panels S0, as described in more
detail herein. As
shown, the lengths of,the flanges 44 may be similar to the lengths of the
extensions 42a.
Each of the flanges 44 may include at least one alignment hole 45, which may
be
threaded and include an upstanding projection 45a. The alignment hole 45 is
adapted to
receive a fastening element 60, which is shown in Figure 6. When the
'alignment hole 45
fully receives the fastening element 60, the floor panel 50 is attached to the
pedestal head
40. As shown best in Figure 4B, the projection 45a protrudes above the top
surface of
the flanges 44 and is received in a complementary countersunk hole (not shown)
in the
lower surface 56 of floor panels 50 to facilitate alignment and connection of
the floor
panels 50 to the pedestal head 40. The outer walls of the projection 45a may
be angled
with respect to a centerline C of the alignment hole 4S as shown in Figure 4B
to form a
complementary engaging surface with the countersunk hole (not shown).
Alternatively
the outer walls of the engaging projection 45a could be parallel to the
centerline C of the
alignment hole 45. . - .
Referring to Figure 4A, distances C1, C2, C3, and C4 each represent the
distance
between the centerline of an alignment hole 4S and the center of one of the
extensions
42a of the plate 42. Preferably, the distances C1, Cz, C3, and C4 are
substantially the
same. As shown, C34 represents the total distance between the centerlines of
the
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alignment hole 45 in the flanges 44 extending from projection 46 on the same
extension
42a.
The L-shaped arms 46, 44 of each extension 42a may be symmetrically disposed
in pairs about the axis A as shown in the side view of Figure 4B. Extension
42a and L-
shaped arms 46, 44 on each side of plate 42 have an inverted, generally U-
shape cross-
section as shown best in Figs. 3 and 4B. The distance Dt represents the
distance between
the inner walls of a pair of projections 46 at the bottom of the top plate 42,
while the
distance D2 represents the distance between the inner walls of the pair of
projections 46
at the junction between the proj ections and flanges 44. Because the L-shaped
arms 46,
44 are designed to deform under panel loading as described below, and in
certain
conditions may deform inwardly towards each other, the distance D2 may be
greater than
the distance Dt. In the preferred embodiments of the invention, DZ is greater
than Dt by
approximately five one hundredths of an inch, but this dimension will
obviously vary
depending upon the particular floor and application being designed. Each L-
shaped arm
1 S 46,44 is supported solely by a portion of a respective extension 42a, thus
forming a
cantilever, which is deformable by loads typically encountered during
installation of the
raised access floor system 10, described in more detail in Figures 8A-8C.
The top plate 42, extensions 42a, projections 46, and flanges 44 ofpedestal
head
40 can be formed integrally by any number of conventional forming techniques,
such as
stamping, casting, or the like. As shown in Figure 5, the pedestal head 40 may
be
stamped from a single piece of material. Figure 5 illustrates a template for
stamping the
plate 42 of the invention. The dashed lines on the template illustrated in
Figure S
indicate where the stamped template is .to be shaped to form the pedestal head
40 of the
invention. Alternatively, the pedestal head may be constructed from any number
of
separately formed pieces that are subsequently attached together. The material
of the
pedestal head 40 can include a variety of metals or composites as long as they
have
sufficient strength, durability, and resiliency to support access floor
panels, according to
the principles of the invention. Currently, the preferred material for the
pedestal head 40
is half hard, high density hot-dipped galvanized steel coil having a yield
strength of at
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least 50,000 pounds per square inch. Preferably, the thickness of the plate is
less than
one-eighth of an. inch, but may, of course vary depending upon the particular
application.
Pedestal head 40 can be used with conventional panels of the type, for
example,.
described herein as floor panels 50. Any type of panel known in the art may be
used in
accordance with the invention. Refernng to Figure 6, a section of a corner of
one of the
floor panels SO is shown. Each of floor panels 50 has an upper surface 52, an
intermediate portion 54, and a Iower surface 56. The upper surface 52 and the
lower
surface 56 are shown as substantially square in shape, but obviously can be
formed in a
variety of geometric shapes. Also, the floor panels 50 can be cut or formed to
adapt the
floor system 10 to a particular configuration. The upper surface 52 typically
is .
substantially parallel to the lower surface 56. The surface area of the upper
surface 52 is
shown as being greater than the surface area of the lower surface 56, thus
forming a lip
or an overhang 52a; which may be extended on the order of less than an inch
from the
side of intermediate portion 54. The intermediate portion 54 extends between
and
connects the upper surface 52 and the lower surface 56. The intermediate
portion 54
may be. hollow, may include a stiffening structure, or may be filled with
various
materials, including wood, metal, composites, or concrete or other materials
to achieve
different strength or aesthetic characteristics as known inthe art. Thus,
depending upon
the application, different types of floor panels may be used. .Although not
shown, a floor
panel lacking panel holes because laminate or carpeting will be applied to the
upper
surface of the floor panel may also be used.
The floor panels 50 may be affixed to pedestal head 40 by fastening elements
60
such as bolts, screws, or pins, or may simply rest on the pedestal head 40. In
either case,
the floor panels 50 are removable for access to an area below the floor panels
50:' Tn the
preferred embodiments, several panel holes 58 are formed in the floor panels
50. Each
of the panel holes 58 is disposed in a corner region of the floor panels 50. .
The panel
holes 58 traverse the entire floor panel 50, i.e.; they extend through the
upper surface 52,
the intermediate portion 54, and the lower surface 56. The panel 50 is
generally aligned
on the pedestal head 40 when disposed in a'corner region 42b between two
extensions
42a. To more precisely align the hole.58 in the panel 50 with the alignment
hole 45 in
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Attorney Docket No. 034913-48-6001
pedestal head 40, the lower surface 56 of at least one corner of panel 50 has
countersunk
hole (not shown) adapted to receive the engaging projection 45a of the
alignment hole
45.
The installation and use of the raised access floor system 10 of the invention
will-
s now be described. Referring to Figures 7 and 8A, after the pedestals 30 are
placed upon
the subfloor 20, the desired number of floor panels 50 are placed upon the
pedestal heads
40 such that the upper surface 52 of the floor panels SO rests on the top
plate 42 and the
extensions 42a of the pedestal head 40, and the lower surface 56 of the floor
panel 50
rests on the flanges 44. As described above, as a corner of floor panel 50 is
manipulated
onto the pedestal head 40, receipt of the projection 45a of the alignment hole
45 into a
complementary engaging surface of the lower surface 56 of the floor panel 50
aligns the
hole 45 in the pedestal head 40 and the panel hole 58. To secure a floor panel
SO to a
pedestal head 40, fastening elements 60 are inserted into panel holes 58 and
alignment.
holes 45 and tightened to connect the panel 50 to pedestal head 40. The method
of
securing floor panels 50 to pedestal head 40 is the same regardless of the
number of floor
panels 40 to be secured. For example, as shown in Figure 8A, a first panel SO
is placed
on a corner 42b of pedestal head 40 such that projection 45a on pedestal head
40 is
received within the countersunk hole (not shown) in panel 50. Then, fastening
element
60 passes through panel hole 58 and is torqued down into alignment hole 45 to
secure
panel SO to pedestal head 40. The same is done with other panels 50. The steps
described herein can be performed in any order.
Refernng to Figures 8A - 8C, certain aspects of the installation of floor
panels 50
onto pedestal head 40 now will be described to illustrate one of the benefits
of the
resilient pedestal head of the invention. Figures 8A - 8C illustrate two floor
panels 50
secured to one of the pedestal heads 40. by two fastening elements 60 in three
different
configurations by virtue of dimensional variances caused by,
e.g.,.manufacturing
tolerances. Figure 8A shows the level configuration that occurs when the panel
holes 58
are perfectly aligned, while Figures 8B and 8C shove angled configurations
that can
occur when the panel holes are not aligned but within tolerance. Referring to
Figure 8A,
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Attorney Docket No. 034913-48-6001
the distance between the centerlines of the panel holes 58 in two adjacent
floor panels 50
is represented by Cp, and the distance between centerlines of corresponding
alignment
holes 45 is represented by C34 (see discussion of Figure 4A above). In Figure
8A, the
distance CP is substantially equal to the distance C34 and the top surfaces of
the panels 50
S are aligned and in the same level plane. When distance Cp is greater than
the distance
C34, by even very small amounts, significant benefits can be achieved to
overcome
misalignment of floor panels 50 during installation caused by dimensional
variations.
For example, it has been found that when distance Cp is slightly greater than
C34, for
example by a difference on the order of 0.010 inches, sufficient pre-bias is
produced in
I O the L-shaped arm 46,44 of the pedestal head 40 to exert forces Fl and F2
and restoring
moments Ml and MZ that tend to press the edges of adjacent floor panels 50
together
after fastening elements 60 are attached to the pedestal head 40. In a
preferred
embodiment of the invention, CP may be 2.000 inches and the distance C3a may
be 1.990
inches. Under these conditions, as the panel holes 58 are aligned with holes
45 in Figure
15 8A are perfectly aligned, when panels 50 are screwed in, the two floor
panels 50 will be
aligned with little or no manipulation required by the installer. Although
prebiasing the
head by designing Cp to be greater than C34 is preferred and is a feature
shown in Figures
8A and 8B, the invention may be practiced with Cp being equal to C34.
Figures 8B and 8C illustrate the alignment feature produced by the resilient
head
20 of the invention when Cp is greater than C34 by more than 0.010 inches or
Cp is less than
. C34. In Figure 8B, the distance Cp between the panel holes 58 of adjacent
panels SO is
greater than the distance C34 by more than 0.010 inches. It is believed that
such a .
discrepancy between the distance Cp and the distance C34 can result, for
example, from
tolerances in manufacturing the,floor panels 50. As the fastening elements 60
are
2S torqued down, the increased distance of Cp causes the fastening element 60
to enter _
aligning hole 4S at an angle transverse to axis A. Because the cantilevered
construction
imparts flexibility in L-shaped arm 46,44, the pedestal head 40 deforms such
that
distance DZ becomes gradually less than distance Dl as fastening element
continues to be
tightened. This deflection of the pedestal head 40 causes the interface
between adjacent
30 panels SO to bow in an upward direction relative to the subfloor 20 as
shown in Figure
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8B. The amount of deflection illustrated in Figure 8B is exaggerated for
illustration
purposes and typically may be on the order of hundredths of an inch. A$er the
fastening
elements 60 have been secured fully to the pedestal head 40, a load can be
applied by the
installer to the bowed floor panels SO in a region near the pedestal head 40
to
permanently deform the pedestal head 40 to the level configuration illustrated
in Figure
8A. Preferably, the load is applied substantially along the axis A in a
direction toward
the subfloor 20. Thus, in this manner, the floor panels 50 can then be aligned
in a level,
substantially horizontal position.
Figure 8C illustrates the condition when the distance CP is less than the
distance
C3a. As the fastening elements 60 are torqued down, the decreased distance of
CP causes
the fastening element to enter aligning hole 45 at an angle transverse to axis
A. Because
the cantilevered construction imparts resiliency in L-shaped arm 46,44, the
pedestal head
40 deforms such that distance DZ becomes greater than distance D1 as fastening
element
60 continues to be tightened. This deflection of the pedestal head 40 causes
the interface
between adjacent floor panels SO to bow in a downward direction relative to
the subfloor
20. Again, the amount of deflection illustrated in Figure 8C has been
exaggerated for
illustration purposes, but may be on the order of hundredths of an inch in
practice. After
the fastening elements 60 have been secured to the pedestal head 40, a load
can be
applied to the bowed floor panels 50 by the installer to permanently deform
the pedestal
head 40 to the level configuration illustrated in Figure 8A. Preferably, the
load is applied
in a direction toward_the subfloor 20 on an end of the panel 50 away from the
pedestal
head 40. Thus, in this manner, the floor panels SO can then be aligned in a
level,
substantially horizontal position. Once the raised access floor system 10 has
been
completely installed and leveled,, the system 10 is rigid by virtue of the
strength of the
individual pedestal heads 40 and by the overall constraint of the
interconnected
system 10. The system 10 of interconnected floor panels 50' and pedestal heads
40
provide greater rigidity than is to be found in an individual pedestal head 40
alone.
In accordance with the present invention, the flooi panels 50 do not have to
be
secured to the pedestal heads 40. For example, as described above, where
carpet or
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Attorney Docket No. 034913-48-6001
laminate is applied to the upper surface 52 of the floor panels 50, the panel
holes 58 are
covered, and thus, unable to accommodate the fastening elements 60. The panels
50
simply rest upon the pedestal head 40. As there are no fastening elements
producing
moments to deform the pedestal head 40, the adjacent panels are aligned
without the
need for manipulation. Of course, there may be some minor misalignment
resulting from
the weight of floor panels 50 alone. However, such misalignment should be
difficult to
detect and can easily be corrected by minor physical manipulation by the
installer. Figure
8A also represents the installed configuration where the floor panels 50
simply rest on
the pedestal heads 40. Figure 8B also is an exaggerated representation of the
unsecured
configuration when a heavy load is applied to the floor panels 50 away from
the pedestal
head. Again, the amount of actual deflection may be on the order of hundredths
of an
inch. After the load is removed from the pedestal heads 40, the cantilevered
construction
of L-shaped arm 46,44 provides sufficient resiliency to pedestal head 40 that
pedestal
head 40 returns to the level configuration illustrated in Figure 8A. Because
in~this
configuration the panels are not secured to the head by fastening elements,
the entire
system 10 is less rigid than the system 10 in which the panels are secured.
Thus, even
though this unsecured configuration may deflect at lower loads, the resiliency
of the
individual panel head 40 is sufficient to return to the level configuration
illustrated in
Figure 8A when the localized load is removed.
Applicants have performed tests to~ demonstrate the resiliency and strength of
the
invention. Applicants attached a single lVlaxcess Technologies, Inc. RWC 400
floor
panel to a pedestal head of the invention constructed according to the
embodiment shown
in Figure 3. The RWC 400 floor panel is a commercially available panel
marketed by
the assignee of the invention that is a resistance-welded, concrete-filled
steel panel
designed for heavy-duty applications. In performing the test, point loads were
applied to
the attached floor panel six inches in from both sides of the corner mounted
on the
pedestal head. Strain gauges were placed near the point of application of the
load on the
panel and at the corner bolt hole on the pedestal head to measure the
deflection of both
the panel and the pedestal head. At a load of 800 pounds, the pedestal head
deflected
0.020 inches and with no measurable permanent deflection. Thus, the head was
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elastically deformed under this loading. At this load, the panel deflected
0.040 inches.
At a load of 1,350 pounds, the pedestal head deflected 0.035 inches and with a
permanent deformation of 0.004 inches. At this load, the panel deflected 0.080
inches.
The ultimate load of the pedestal head before failure was determined to be
greater than
S 3,000 lbs. with a corresponding permanent deformation of O.I O inches.
Figures 9, 10A, l OB, and 11 illustrate another embodiment of a pedestal head
of
the invention. Like numbers will be used to describe like elements. As shown
in Figure
9, the pedestal head 140 is fixedly connected to the rod 136 by any means
known in the
art, such as welding or by providing the pedestal head 140 with a
complementary surface
(not shown) adapted to engage the threaded surface of the rod 136. As
described above,
the position or height of the pedestal head 140 relative to the subfloor 20
changes when
the height of rod 136 is adjusted within post 134 by nut 38. Pedestal head 140
generally
includes a top plate 142 having four L-shaped arms formed by downwardly
depending
projections 146 and flanges 144 outwardly extending therefrom in a
cantilevered fashion
for supporting floor panels 50. As the top plate 142 is adapted to support one
or more
floor panels 50 in a manner discussed herein, the top (uppermost) surface of
the top~plate
142 will typically be substantially flat as illustrated. Thus, the top surface
of the top
plate 142 lies in a plane substantially horizontal and substantially
transverse to vertical
axis A shown in Figure 10B. Extending outwardly from the center of the top
plate 142 -
are four extensions 142a, each of which preferably have substantially the same
length.
The top surface of extensions 142a form four comers 142b on the top surface
each of
which receives a corner of a panel 50. Top plate 142 includes skirt 142c to
strengthen
top plate 142. Unlike the embodiment shown in Figure 3, the L-shaped arms
146,144 in
this embodiment depend from each extension 142a, such that each extension has
a
strengthening skirt on one side and an arm 146,144 on the other. The top plate
142 may
include a number of holes 142d formed in extensions 142a for manipulating and
aligning
the pedestal head 40 during manufacture of the pedestal head 140, during the
stamping
and forming process described below. The projections 146 depend downwardly
from one
side of each extension 142a such that the flanges 144 are spaced from and
substantially
parallel to the surface of the tap plate 142. Flanges 144 each have
substantially the same
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length and are adapted to support a corner portion of the floor panels 50, as
described in
more detail herein. As shown, the lengths of the flanges 144 may be similar to
the
lengths of the extensions 142a. Each of the flanges 144 may include at least
one
alignment hole 145, which may be threaded and include an upstanding projection
145a,
and functions in the same manner as discussed above in connection with the
first
embodiment of pedestal head 40 to facilitate alignment and connection of the
panels 50
to head 140.
Referring to Figure 10A, distances C1, C2, C3, and C4 each represent the
distance
between the centerline of an alignment hole 145 and the center of one of the
extensions
142a of the plate 142. Preferably, the distances C1, C2, C3, and C4 are
substantially the:
same. As shown, C34 represents the total distance between the centerlines of
the
alignment hole 145 in the flanges 44 on one side of the plate.
The projections 146 of each extension 142a may be parallel to the vertical
axis A
as shown in Figure 10B. The top plate 142, extensions 142a, projections 146,
and
flanges 144 of pedestal head 140 can be formed integrally by any number of
conventional forming techniques, such as stamping, casting, or the like. As
shown in
Figure 11, the pedestal head 140 preferably is stamped from a single piece of
material.
Figure 11 illustrates a template for stamping the plate 142 of the invention.
The dashed
lines on the template illustrated in Figure 11 indicate where the stamped
template is to be
shaped to form the pedestal head 140 of the invention, Like the first
embodiment, the
pedestal head may also be constructed from any number of separately formed
pieces that
are subsequently attached together, and the material of the pedestal head 40
can include a
variety of metals or composites as long as they have sufficient strength,
durability, and
resiliency to support access floor panels according to the principles of the
invention. The
installation and use of the embodiment of the invention illustrated by Figures
9, 10A,
l OB, and 11 are substantially the same as that described above and in Figures
8A- 8C,
and thus, will not be repeated here.
Although the foregoing description is directed to the preferred embodiments of
the invention, it is noted that other variations and modifications will be
apparent to those
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Attorney Docket No. 034913-48-6001
skilled in the art, and may be made without departing from the spirit or scope
of the
invention.
1-WA1169 t 557.1
