U.S. patent application number 11/626331 was filed with the patent office on 2007-08-23 for rebar support chair.
This patent application is currently assigned to DAYTON SUPERIOR CORPORATION. Invention is credited to Clifford D. Bennett, Kenneth Lee.
Application Number | 20070193189 11/626331 |
Document ID | / |
Family ID | 39643930 |
Filed Date | 2007-08-23 |
United States Patent
Application |
20070193189 |
Kind Code |
A1 |
Bennett; Clifford D. ; et
al. |
August 23, 2007 |
Rebar Support Chair
Abstract
A chair for supporting and spacing concrete reinforcement
members having an integrally formed body including an upper
receiving area and a lower base, where the receiving area includes
a vertical fin defining an open notch for receiving a concrete
reinforcement member. The receiving area may further include a
gusset projecting from the vertical fin and extending upward to
define a medial, lowest portion of the associated open notch. The
vertical fin and gusset are adaptable such that chairs having
different heights can be manufactured using a single molding
apparatus.
Inventors: |
Bennett; Clifford D.;
(Fontana, CA) ; Lee; Kenneth; (Anaheim,
CA) |
Correspondence
Address: |
THOMPSON HINE L.L.P.;Intellectual Property Group
P.O. BOX 8801
DAYTON
OH
45401-8801
US
|
Assignee: |
DAYTON SUPERIOR CORPORATION
7777 Washington Village Drive, Suite 130
Dayton
OH
45459
|
Family ID: |
39643930 |
Appl. No.: |
11/626331 |
Filed: |
January 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10606498 |
Jun 26, 2003 |
|
|
|
11626331 |
Jan 23, 2007 |
|
|
|
Current U.S.
Class: |
52/677 |
Current CPC
Class: |
E04C 5/20 20130101; E04C
5/168 20130101 |
Class at
Publication: |
052/677 |
International
Class: |
E04C 5/16 20060101
E04C005/16 |
Claims
1. A chair for supporting and spacing concrete reinforcement
members, comprising: an integrally formed body including an upper
receiving area and a lower base, the receiving area including a
vertical fin defining an open notch for receiving a concrete
reinforcement member, and the base adapted to rest on a planar
support surface.
2. The chair of claim 1, wherein the receiving area further
includes a gusset projecting from said vertical fin.
3. The chair of claim 2, wherein the gusset extends upward to
further define a medial, lowest portion of an associated open
notch.
4. The chair of claim 2, wherein the receiving area includes a pair
of opposing gussets projecting perpendicularly from the vertical
fin.
5. The chair of claim 4, wherein the base includes four supporting
legs, with two of the legs being projections extending from the
vertical fin.
6. The chair of claim 4, wherein the base includes four supporting
legs, with two of the legs being projections extending from the
opposing gussets.
7. The chair of claim 1, wherein the receiving area includes four
vertical fins defining two pairs of diametrically opposed open
notches, the medial, lowest portions of the first pair of opposed
open notches being located at a different height above the support
surface than the medial, lowest portions of the second pair of
opposed open notches.
8. The chair of claim 7, wherein the receiving area further
includes a gusset projecting inwardly from each vertical fin.
9. The chair of claim 8, wherein each gusset extends upward to
further define a medial, lowest portion of an associated open
notch.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 10/606,498, filed Jun. 26, 2003, the entirety
of which shall be incorporated herein by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] The present disclosure relates generally to chairs and
spacers that are used in construction activities for the support of
steel reinforcement members within concrete structures, and in
particular to a stackable chair that reliably retains reinforcement
bars, post-tension cables, rods, and the like.
[0004] 2. Description of the Related Art
[0005] Chairs or spacers are commonly used in the construction
industry for the support and positioning of steel reinforcement
members such as post-tension cables and/or reinforcement bars
("rebar") a proper distance above a surface. Rebar is usually
arranged in rows or grids within an area into which concrete is to
be poured, and held loosely in place while concrete is placed
around it. In normal use, a receiving area formed on the chair will
contact and support the rebar while the base of the chair rests on
a deck or on a grade.
[0006] Proper spacing and arrangement of steel reinforcement
members in concrete slabs according to known engineering and
architectural specifications impacts the structural strength and
integrity of the concrete structure. Such steel reinforcement
requires sufficient cover to avoid exposing the steel to the
effects of moisture-penetrating corrosion. Once the steel is
exposed to the effects of chemical-laden moisture, corrosion starts
taking effect.
[0007] Known prior art chairs have desirable features which provide
the proper support of rebar or post-tension cables safely within a
concrete structure. Some chairs also have additional desirable
features. For example, U.S. Pat. No. 5,729,949 to Hartzheim
discloses a readily stackable chair with a hollow-conical body that
minimizes the amount of shipping and storage space required. These
chairs have support legs with apertures between them to allow
concrete to flow into the hollow interior of the chair. A worker
can carry many chairs at one time and place numerous chairs at a
construction site without repeated trips to a storage area.
[0008] U.S. Pat. No. 6,089,522 to Haslem et al. discloses a
stackable high chair having a lower base portion, an upper
connecting portion and an upper support surface. The upper support
surface includes bisecting cross members which join opposing
corners of the upper support surface. Inclined ramps extend
upwardly from the support surface and serve to position the rebar
along the upper surface. The upper support surface also includes a
plurality of holes which allow a head piece to be mounted to the
chair, thereby allowing the height of the chair to be readily
adjusted.
[0009] While the prior art chairs described above may be useful for
their respective, particular objectives, a need exists for a
stackable chair that is tall enough to support rebar a significant
distance above a surface, yet has a simple and strong construction.
A further need exists for an economical chair having a uniform base
portion and an integral but adaptable receiving area portion, such
that a plurality of chairs providing support at different heights
may be manufactured using a single molding apparatus.
BRIEF SUMMARY
[0010] Accordingly, one objective of the present invention is to
provide a chair with a simple yet strong design that is tall enough
to support rebar a significant distance above a surface. It is also
an objective to provide a tall chair that is light in weight yet
able to securely support rebar. Yet another objective is to provide
a tall rebar support chair with a wide base that allows the chair
to stand securely. It is a further objective to provide a rebar
support chair that can be stacked within another chair to provide a
more efficient method for packaging, storage, and shipment. It is
also a further objective to provide a rebar support chair including
an integral receiving area that is adaptable for supporting rebar
at different heights above support surface yet manufacturable using
a single molding apparatus. Yet another objective is to provide a
plastic chair made of durable, non-corroding materials that is easy
to manufacture and easy to use.
[0011] Briefly stated, these objectives are accomplished by a
generally funnel-shaped support chair having a hollow body with an
inner surface, an outer surface, a receiving area, and a base. The
base defines a lower opening and is adapted to rest on a planar
support surface. The receiving area is adapted to receive and
support the rebar. The lower opening of the chair is larger than
the receiving area, and the inner and outer surfaces are
substantially complementary to each other to allow a plurality of
chairs to be stacked within each other for storage and shipment.
Additionally, the stacking feature allows a worker to carry a stack
of chairs at the job site as he places them at desired
locations.
[0012] In one aspect of the disclosure, the receiving area includes
a first and a second pair of curved notches, with the second pair
being oriented ninety degrees from the first pair. The first pair
of notches has a first depth, and the second pair of notches has a
second depth. The first pair is deeper than the second pair, and
the chair is thus able to support rebar at different heights and in
perpendicular relationships to one another. The receiving area may
optionally include a plurality of bridges. A bridge is a band of
material that spans the distance within the body of the chair
between each of the pairs of notches. The bridges can assist to
further increase the supporting strength of the chair, and can
connect the medial, lowest portions, or troughs, of the
notches.
[0013] In another aspect of the disclosure, the base includes a
plurality of support legs which define a plurality of apertures,
and the apertures allow poured concrete to pass fluidly through the
chair. The apertures are preferably arch-shaped, and the support
legs preferably have a thickened band of material around the
apertures, such that the strength of the chair is reinforced by
these thickened areas to allow the support legs to be longer yet
retain their strength. In one particular aspect, the base has four
support legs, with two of the support legs further including foot
members extending horizontally outwardly therefrom, the other two
support legs lacking a foot member. In such an aspect, the foot
members extend from support legs which are diametrically opposed
from one another. In another particular aspect, the base has four
support legs, with adjacent support legs being joined by a
horizontal strut. In such an aspect, the horizontal struts
collectively form a closed, geometrically shaped hoop to prevent
buckling or spreading of the support legs.
[0014] In another aspect of the disclosure, the base includes upper
and lower support legs. The lower support legs are the primary set
of legs and are larger than the upper support legs. The receiving
area is supported by both the upper and lower support legs, with
the upper legs extending downwardly from the receiving area, and
the lower support legs extending downwardly from the upper support
legs. In one particular aspect, the upper legs can include upwardly
extending ribs on their outer surface. These ribs extend along each
of the upper support legs between the junction of the lower and
upper legs. In such an aspect, the chair can be made to be
significantly taller than other chairs of the prior art, and also
be light in weight yet strong enough to support rebar securely, and
without collapsing under the weight of the rebar. Preferably the
chair is advantageously manufactured as a single piece of material,
such that the chair can have the height and strength of a chair
having a head piece seated on top of a base chair, yet be a single,
tall chair with two sets of support legs.
[0015] In accordance with another aspect of the disclosure, the
body of the chair has multiple substantially straight sides and a
substantially square cross-section having rounded corners, with an
inner surface that is complementary to the outer surface to allow a
plurality of chairs to be stacked together, one inside the other,
for storage and shipment. The chair may also have an elliptical,
oval or hybrid cross-section. The chair preferably has a wide base
which is adapted to rest on a flat support surface. The lower
opening is defined by the base and is preferably larger than the
upper receiving area, and the inner and outer surfaces are
preferably substantially complementary to each other.
[0016] In accordance with another aspect of the disclosure, a chair
includes an adaptable receiving area having a vertical fin defining
an open notch. The receiving area of the chair also preferably
includes a gusset projecting perpendicularly from the vertical fin
and extending upward to further define the medial, lowest portion
of the notch. In one particular aspect, the receiving area of the
chair includes four vertical fins defining a first and a second
pair of opposed open notches, with first and second pairs of
notches being oriented at ninety degrees from each other. The
medial, lowest portion of the first pair of notches is located at a
lower height than the corresponding portion of the second pair of
notches, and the chair is thus able to support rebar at different
heights and in perpendicular relationships to one another.
Preferably, the receiving area also includes a gusset projecting
perpendicularly inward from each vertical fin and extending upward
to the medial, lowest portion of each notch to further increase the
supporting strength of the vertical fins. In another particular
aspect, the receiving area of the chair includes one vertical fin
defining an open notch, and a pair of gussets projecting
perpendicularly outward from the vertical fin and extending upward
to the medial, lowest portion of the notch to both increase the
supporting strength of the vertical fin and provide a resistance to
tipping.
[0017] In accordance with another aspect of the disclosure, the
receiving area and the base are integrally formed together from a
durable, non-corroding polymeric material. The chairs are easy to
manufacture in this fashion, and packaging and storage of the
chairs can be done quickly and easily because the chairs are also
stackable. These and other aspects of the disclosure will be more
fully appreciated with respect to the following drawings and
detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a perspective view of one aspect of a chair;
[0019] FIG. 2 is a perspective view of the chair of FIG. 1 in which
rebar has been placed in the receiving area;
[0020] FIG. 3 is a perspective view of another aspect of a chair
having two sets of support legs;
[0021] FIG. 4 is a perspective view of a plurality of chairs of
FIG. 1 stacked within one another in accordance with one aspect of
the disclosure;
[0022] FIG. 5 is a perspective view of a plurality of chairs of
FIG. 3 arranged in a stack;
[0023] FIG. 6 is a perspective view of one aspect of a chair having
an adaptable receiving area including vertical fins;
[0024] FIG. 7 is a perspective view of another aspect of a chair
having vertical fins, illustrating the adaptability of the
receiving area;
[0025] FIG. 8 is a perspective view of another aspect of a
stackable chair having vertical fins and horizontal struts;
[0026] FIG. 9 is an elevational cut-away view of a mold for
manufacturing a chair having an adaptable receiving area including
vertical fins.
DETAILED DESCRIPTION
[0027] Referring now to FIG. 1, a perspective view is shown of one
aspect of a chair 8 having a hollow body 10 including a base 12, a
receiving area 14, an inner surface 16, an outer surface 18, and
ribs 20 formed on the outer surface for a purpose described below.
The base 12 defines a lower opening 22 and is adapted to rest on a
planar support surface. The receiving area 14 has a plurality of
generally rounded notches 24, with elevated notch junctions 26
between adjacent notches. The lower base 12 has a plurality of
separate support legs 32 extending downwardly from the receiving
area 14. Foot members 34 extend radially outward from two opposing
support legs 32. Adjacent support legs 32 define holes or apertures
36, which allow poured concrete to fluidly pass through the chair
8. The legs 32 have a thickened band of material 40 around each
aperture 36.
[0028] The chair of FIG. 1 is preferably generally square in
cross-section having rounded corners and is constructed of a single
piece of resilient polymeric material. However, alternative aspects
of the chair may have a polygonal, elliptical, oval or hybrid
cross-section. The receiving area 14 is adapted to receive and
support concrete reinforcement members, or rebar. The inner surface
16 is complementary to the outer surface 18, and the body 10 has
multiple straight sides and is generally tapered, with the lower
opening 22 being larger than the receiving area 14, thereby
allowing multiple chairs to be stacked within one another for
storage and shipment. The tapered shape of the chair also requires
that the upper portion of the body 10, including the receiving area
14, is generally relatively narrow as compared to the lower
portion, which includes the wider base 12. Ribs 20 function to
space stacked chairs and facilitate their separation.
[0029] The apertures 36 between the support legs 32 are preferably
arch-shaped and allow fluid concrete to pass through the body 10
beneath the level of the receiving area 14. The large openings
provided by the apertures 36 maximize the free flow of concrete
into and around chair 8. The support legs 32 preferably have a
thickened band of material 40 around the apertures 36, such that
the strength of the chair is reinforced by these thickened areas 40
to allow the support legs 32 to be longer yet retain their
strength. As shown, the base 12 has four support legs 32, with two
of the support legs further including foot members 34 extending
horizontally outwardly therefrom, the other two support legs
lacking a foot member. In FIG. 1, the foot members 34 extend from
support legs 32 which are diametrically opposed from one
another.
[0030] FIG. 2 shows reinforcement members 38 and 39 being supported
by the chair 8 of FIG. 1. Reinforcement members 38 and 39 intersect
with one another within the receiving area 14. The receiving area
14 includes a first and a second pair of curved notches, 24a and
24b, respectively, with the second pair 24b being oriented ninety
degrees from the first pair 24a. The notches 24a, 24b comprise
curved bearing surfaces extending inwardly from outer surface 18.
The first pair 24a are deep notches which receive rebar member 38,
and the second pair of notches 24b are shallow notches which
receive rebar member 39, such that rebar member 39 is situated
above and perpendicular to member 38 within the receiving area 14.
The chair 8 is thus able to support rebar members 38 and 39 both at
different heights and in perpendicular relationships to one
another.
[0031] As a non-limiting example of how the reinforcement members
38 and 39 are placed within the chair 8, reinforcement member 38 is
initially positioned over the receiving area 14 and then lowered
into the deep notches 24a. Reinforcement member 39 is then lowered
into the shallow pair of notches 24b. Notch pairs 24a are
preferably deep enough to allow reinforcement member 38 to sit
within the receiving area 14 while also allowing member 39 to sit
completely within the shallow notch pairs 24b without interference
from member 38.
[0032] FIG. 2 further illustrates the tapered shape of the chair 8.
The upper portion of body 10 is narrow at the receiving area 14.
The body 10 gradually widens from the notch junctions 26 down to
the ends of the support legs 32. The lower opening 22 is therefore
much larger in circumference than the receiving area 14. Also, each
support leg 32 proceeds downwardly in a straight line from a
junction 26. Preferably, two of the support legs 32 have a foot
member 34 extending horizontally outwardly therefrom, adding
further support to the base such that the base is well adapted to
support the weight of the chair 8 as well as the reinforcement
members 38, 39.
[0033] FIG. 3 illustrates another aspect of the chair 108 in which
the base 112 includes both lower 132 and upper 133 support legs.
The lower support legs 132 are the primary set of legs and are
larger and longer than the upper support legs 133. The receiving
area 114 is supported by both the upper and lower support legs 132,
133, with the upper legs 133 extending downwardly from the
receiving area 114 and defining upper apertures 137, and the lower
support legs 132 extending downwardly from the upper support legs
133 and defining lower apertures 136. A ledge 142 defines the
junction between the upper 133 and lower 132 legs, and can be seen
extending around the circumference of the body 110.
[0034] As shown in FIG. 3, the base 112 has four lower support legs
132, with two of the lower support legs 132 further including foot
members 134 extending horizontally outwardly therefrom, the other
two lower support legs lacking a foot member. The foot members 134
extend from diametrically opposed lower support legs 132. Upwardly
extending ribs 120 are disposed on outer surface 118 and act as
spacers to facilitate separation of stacked chairs, as described
above with respect to ribs 20 of FIGS. 1 and 2.
[0035] The lower and upper apertures 136, 137 between the lower and
upper support legs 132, 133, respectively, are preferably
arch-shaped and allow fluid concrete to pass through the body 110
beneath the level of the receiving area 114. The large openings
provided by the apertures 136, 137 maximize the free flow of
concrete into and around chair 108. The lower support legs 132
preferably have a thickened band of material 140 around the lower
apertures 136, such that the strength of the chair is reinforced by
these thickened areas 140 to allow the lower support legs 132 to be
longer yet retain their strength.
[0036] The receiving area 114 shown in FIG. 3, similar to the
receiving area 14 in FIGS. 1 and 2, is adapted to receive and
support concrete reinforcement members, or rebar. The inner surface
116 of the base 112 and receiving area 114 is complementary to the
outer surface 118, and the body 110 has multiple straight sides and
is generally tapered, with the lower opening 122 being larger than
the receiving area 114, thereby allowing multiple chairs to be
stacked within one another for storage and shipment.
Advantageously, the stackable chairs 108 facilitate handling on a
job site, whereby workers may carry a stack of chairs 108 in one
hand while placing individual chairs from the stack at desired
locations at the job site.
[0037] The receiving area 114 of FIG. 3 further includes a
plurality of bridges 128. A bridge junction 130 is formed where two
bridges 128 meet in the center of the receiving area 114. The
bridges 128, which are shown here but are an optional element of
the chair 108, connect the medial, lowest portions, or troughs, of
the notches 124, and span the distance within the body 110 of the
chair between the notches 124. The bridges 128 assist to further
increase the supporting strength of the chair 8. The bridges 128,
which are optional, serve to support the rebar members 138 and 139
as they traverse the body 110 of the chair, and add strength and
support to the structure.
[0038] Apertures are shown in FIGS. 1 through 3 as being generally
arch-shaped, curved at the apex. One of skill in the art will
recognize, however, that a variety of shapes, sizes, and numbers of
apertures can be used. Support legs are generally of sufficient
width and strength to support a substantial load, such as the force
of the reinforcement members as well as the force applied by
construction workers who may step or walk on the reinforcement
members during the construction process. The thickened band of
material around the apertures also adds strength to the structure,
so that the chair does not collapse under such weight. Each foot
member allows the base to rest on a flat, planar support surface,
including loose or pliant surfaces such as dirt, sand, or the
like.
[0039] As illustrated in FIG. 4, a plurality of chairs 8a and 8b
can be stacked together, one inside the other, for packaging,
storage and shipment. The combination of the tapered, generally
funnel-like shape of chairs 8a and 8b, along with the complementary
surfaces, allows the upper receiving area of chair 8a to be
inserted within the lower opening 22 of chair 8b, such that the
outer surface 18a of the first chair slidably engages the inner
surface of the second chair. The distance that a first chair is
able to fit inside a second chair is dependant upon the degree of
slope assumed by the surfaces 16 and 18 as the body 10 progresses
from the receiving area 14 to the lower opening 22. That is, the
smaller the receiving area is relative to the lower opening 22, the
greater the slope will be of the surfaces 16 and 18. Preferably,
this slope is sufficient to allow a substantial portion of the
first chair to fit within the second chair, such that a great
number of chairs can be stacked in a minimal amount of space
without the stack becoming too tall or burdensome. As noted above,
ribs 20 space stacked chairs and facilitate their separation.
[0040] As shown in FIG. 5, the chairs shown in FIG. 3 can be
similarly stacked with the foot members of one chair on opposite
support legs as the foot members of the preceding chair, or
alternatively the foot members can be on the same corresponding
support leg, such that a user can recognize a specific corner of
the chair. It will be apparent that the stacking capability allows
a workman to carry a stack of chairs with one hand as he places
chairs at the job site.
[0041] Referring now to FIG. 6, a plurality of chairs 208 similar
to the chair shown in FIG. 3 may be manufactured by combining a
base 212 with an adaptable receiving area 214. The base 212 may be
generally identical to the base 112 described previously, with
similar reference numerals used to indicate similar structure,
e.g., lower 232 and upper 233 support legs. The base 212 may also
be generally identical to the base 12 described previously, the
relevant characteristic being that the base portion or body of the
chairs 208 is essentially uniform with regard to both size and
structural design. The adaptable receiving area 214 may include
four vertical fins 250 defining a first 224a and a second 224b pair
of opposed open notches. The term "vertical fin" as used herein
shall mean a vertically projecting structure having uniform lateral
extents, and include structures providing stepwise and/or
progressively expanding voids defined within such extents. The term
"open notch" as used herein shall mean that the space directly
above the entirety of the notch feature is free from obstructions
such as overhangs, latching projections, or other means for
impeding the vertical movement of rebar, post-tension cable, and
the like away from the notch. The inner surface 216 of the base 212
is generally complementary to the outer surface 218, with a lower
opening 222 being larger than the receiving area 214, thereby
allowing multiple chairs to be stacked primarily within one another
for storage and shipment. The vertical fins 250 will space stacked
chairs and facilitate their separation, such that ribs 20, 120 may
be omitted.
[0042] The first pair of notches 224a and the second pair of
notches 224b are oriented at ninety degrees from each other, with
the medial, lowest portion, of the first pair of notches 224a being
located at a lower height than the corresponding portion of the
second pair of notches 224b. Thus, a single chair 208 may support
rebar at different heights and in perpendicular relationships to
one another. For example, a chair 208 may support a single portion
of rebar at one of two heights above a support surface, e.g., at
5.25'' or at 5.5'' above grade, or support a rebar grid in an
overlapping, perpendicular relationship, e.g., at 5.25'' and 5.5''
above grade.
[0043] The receiving area 214 of a plurality of chairs 208 is
adaptable such that different chairs 208 may provide support at
different heights above a support surface yet be manufacturable
using a single molding apparatus. The receiving area 214 is adapted
by altering the length of the vertical fins 250 to vary the height
of the medial, lowest portion of the notches 224. For example, a
second chair 208 having longer vertical fins 250 but an essentially
identical base 212 may support a single portion of rebar at one of
two other heights above a support surface, e.g., at 5.75'' and
6.0'' above grade, such that two slightly varying chairs 208 may
manufactured which collectively offer support for rebar at four
differing heights above a support surface. Advantageously, altering
the manufactured length of the vertical fins 250 permits a supplier
to produce a line of such varying chairs using a single molding
apparatus, as described below.
[0044] In aspects such as the one described above, each vertical
fin 250 is preferably reinforced by a perpendicular gusset 252
projecting inwardly from the vertical fin 250 and extending upward
to further define the medial, lowest portion of the associated
notch 224. The gusset 252 increases the supporting strength of the
vertical fin, preventing both lateral deformation and localized
crushing of the fin by rebar, post-tension cable, and the like that
is received in the notch. The manufactured length of the gussets
252 may also be altered to permit production of varying chairs
using a single molding apparatus.
[0045] FIG. 7 illustrates another aspect of a chair 308 combining a
generally cruciform body 310 including four support legs 332 with
an adaptable receiving area 314. Two opposing support legs 332 may
configured as projections extending laterally and downward from a
vertical fin 350 defining an open notch 324. Two other opposing
support legs 332 may be configured as projections extending
laterally and downward from a pair of opposing gussets 352
projecting perpendicularly outward from the vertical fin 350. The
gussets 352 both extend upward to further define the medial, lowest
portion of the notch 324, and to increase the supporting strength
of the vertical fin. Such gussets 352 may also provide a resistance
to tipping by reducing the tendency of rebar to catch on the edges
of the open notch 324, and by repositioning a rebar's applied
weight toward that portion of the chair 308 having a tendency to
rotate upward in response to a longitudinal movement of the
rebar.
[0046] FIG. 8 illustrates yet another aspect of a chair 408
combining a body 410 with an adaptable receiving area 414. The body
410 has a plurality of support legs 432 extending downwardly from
the receiving area 414. Each leg 432 is joined to adjacent legs 432
by a horizontal strut 444, and the horizontal struts 444
collectively form a closed, geometrically shaped hoop 446 to
prevent buckling or spreading of the legs 432. Adjacent support
legs 432 define holes or apertures 436, which allow poured concrete
to fluidly pass through the chair 408. The legs 432 may also have a
thickened band of material around each aperture 436, such that the
legs 432 have a T-shaped or cruciform profile (not shown). The legs
432 and horizontal struts 444 jointly define a lower opening 422.
The body 410 is generally tapered, with the lower opening 422 being
larger than the receiving area 414, thereby allowing multiple
chairs to be stacked primarily within one another.
[0047] The receiving area 414 includes a vertical fin 450 defining
an open notch 424 and a pair of opposing gussets 452 projecting
perpendicularly outward from the vertical fin 450. The gussets 452
may each extend upward to further define the medial, lowest portion
of the notch 424. The gussets 452 increase the supporting strength
of the vertical fin, and may also provide a resistance to tipping
by reducing the tendency of rebar to catch on the edges of the open
notch 424, and by repositioning a rebar's applied weight toward
that portion of the chair 408 having a tendency to rotate upward in
response to a longitudinal movement of the rebar. With particular
reference to the structure shown in FIG. 8, two of the opposing
support legs 432 may be projections extending laterally and
downward from the vertical fin 450, and two of the other opposing
support legs 432 may be projections extending laterally and
downward from the opposing gussets 452.
[0048] In aspects such as the one described above, when multiple
chairs are stacked, interference between the legs 432 of one chair
408 and the hoop 446 of a second chair 408 will substantially
constrain horizontal movement of the bottom of the second chair
408. The efficiency of such stacking will vary depending upon the
length of the vertical fin 450, but still permit storage and
shipment within a reduced volume, and still permit a worker to
carry many chairs at one time at a construction site.
[0049] As discussed above, altering the manufactured length of the
vertical fins 250, 350, 450 permits a supplier to produce a line of
chairs providing support at different heights using a single
molding apparatus. Referring now to FIG. 9, a mold 500 may be
formed, shaped, or otherwise manufactured to provide a mold cavity
having the basic configuration of a chair, e.g., chair 208,
including the body 210, 310, 410 and receiving area 214, 314, 414
but excluding any vertical fins 250, 350, 450 otherwise included in
the receiving area. The mold may further include or subsequently be
modified to include a first channel 510 having a cross-section
corresponding to the cross-section of a first vertical fin 250, a
second channel 510 having a cross-section corresponding to the
cross-section of a second vertical fin (if present), etc.
[0050] The mold may also include a first adjustable blade 520
having a cross-section corresponding to the cross-section of the
first vertical fin 250, a second adjustable blade 520 having a
cross-section corresponding to the cross-section of the second
vertical fin (if present), etc. Each adjustable blade 520 may be
fully inserted into its corresponding channel 510 such that the
inserted end 525 of the blade 520 defines a top surface of the
notch in the receiving area of the chair. However, each adjustable
blade 520 may also be partially withdrawn into its corresponding
channel 510 such that material may enter the channel 510 to form a
vertical fin 250, with the inserted end 525 of the blade 520
defining a top surface of the notch 224 in the vertical fin 250. By
adjusting the insertion of each blade 520, a supplier may adjust
the length of the vertical fins 250, 350, 450 in a chair to produce
a plurality of chairs providing support at different heights above
a support surface using a single molding apparatus.
[0051] In aspects where gussets 252, 352, 452 are present, the mold
may include a channel 510 and blade 520 having cross-sections
corresponding to the cross-section of the vertical fin 250, 350,
450 and the associated gusset(s) 252, 352, 452. The inserted end
525 of the blade 525 will consequently further define the top
surface of the associated gusset(s) 252, 352, 452 and preferably
further define the structure associated with the medial, lowest
portion of the notch 224, 324, 424.
[0052] The chairs disclosed herein can be made significantly taller
than most chairs of the prior art, and are also light in weight yet
strong enough to support rebar securely, without collapsing under
the weight of the rebar. Preferably the chairs are advantageously
manufactured as a single piece of material, and constructed from a
resilient polymeric material and, more specifically, constructed of
a plastic or resin material. In this manner, the chairs can have
the height and strength of a chair with a head piece seated on top
of a base chair, yet be a single, tall chair. Further, the chairs
are most preferably made of polypropylene and are one-piece
injection molded. One of ordinary skill in the art will recognize
that other materials exhibiting similar characteristics of being
lightweight, strong and resilient can be used, such as
polyethylene, a combination of polypropylene and polyethylene, and
other known materials.
[0053] The present invention has been disclosed in detail in
connection with the preferred embodiments. While there are many
modifications that can be made without departing from the scope of
the present invention, the present invention is defined by the
claims that follow.
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