Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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MODULAR FRAMEWORK FOR A CURVED OR GRAND STAIRCASE
This application claims the benefit of US Provisional Application
62/114,664 filed February 11,2015.
FIELD OF THE INVENTION
The present invention relates generally to a modular framework for a
staircase, and more particularly the present invention relatives to a modular
framework for a curved staircase that comprises a plurality of plates cut from
sheet
metal.
BACKGROUND
The unique designs, especially the curvature, of curved staircases and
grand staircases makes them aesthetically pleasing. While curved staircase
comprise
inner and outer stringers which have constant curvature generally in one
direction,
grand staircases may comprise at least one stringer which is curved more than
once
in two different directions (i.e., the stringer has a convex portion and a
concave
portion to its shape in plan view). As such, a curved or grand staircase may
add
considerable value to a building. However, knowledge and craftsmanship
required to
build this type of staircase means that a cost of the curved or grand
staircase is
significant compared to rectilinear staircases which are simpler in design. In
fact,
building curved and grand staircases is often regarded as an art form because
of the
complexity in fabricating and assembling pieces of the staircase. As such, it
is likely
that building owners may be dissuaded from installing more aesthetically
pleasing
staircase designs such as those of the curved or grand staircase type based on
the
sheer cost often associated with these staircases.
Fabrication and assembly of staircases in sections, especially of a
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framework of the staircases, has been known in the art of staircase building
for some
time. It serves as one way of reducing the costs associated with installing
staircases
by fabricating parts of a modularized framework and assembling the parts
thereof on-
site. For example, U.S. Patent No. 4,422,270 to Lapointe teaches a modular,
self-
supporting staircase. The staircase is made up of sections. Each section
includes two
vertical side plates and a tread supported across the side plates. The side
plates have
vertical flanges which overlap a portion of an adjacent side plate that is
part of an
adjacent step of the staircase. The vertical side plates also have an upper
flange
which is L-shaped in plan view that supports the tread thereon. While the
patent to
Lapointe may solve the problem of providing inexpensive metal framework in
sections, one potential shortcoming of the patent to Lapointe may be
difficulty to adapt
to the curved staircase.
Another example of modularized staircase design is German Patent
Application 102011015492 to Uhlenbusch. The patent to Uhlenbusch describes
stringer sections which are made from sheet metal. Each stringer section has
vertical
flanges that are perpendicular to a main portion of the plate that is
substantially
planar. The vertical flanges of pairs of adjacent plates overlap for coupling
the
sections together. One of the potential shortcomings of the patent to
Uhlenbusch may
be difficulty to adapt to the curved or grand staircase.
The Applicant provides a unique solution for curved or grand staircases
that may be less expensive to manufacture; easier to assemble on-site at the
building;
and which may make curved staircases and grand staircases more accessible to
those individuals who may not be able to afford installation of traditional
curved or
grand staircases.
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SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a modular
staircase framework for assembly in sections comprising:
a plurality of steps, each step comprising:
a first stringer plate;
a second stringer plate laterally opposite the first stringer plate;
the first and second stringer plates being oriented substantially
upright and substantially parallel to one another;
the first and second stringer plates having opposing first and
second upright edges; and
a tread plate spanning between the first and second stringer
plates in a horizontal orientation;
the first stringer plates of the steps collectively defining a first stringer
and the second stringer plates of the steps collectively defining a second
stringer;
within each pair of adjacent steps, the stringer plates of each respective
stringer being aligned so that the first upright edge of the stringer plate of
one step is
adjacent the second upright edge of the stringer plate of another step;
within at least one pair of adjacent steps:
at least one of the first or second stringer plates of a first step
comprising a receiving element at or adjacent the first upright edge thereof;
and
at least one of the first or second stringer plates of a second step
comprising a coupling element at or adjacent the second upright edge thereof
for
coupling to the receiving element of an adjacent one of the stringer plates of
the first
step;
wherein the first and second stringer plates and the tread plate are
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fabricated from sheet metal using a cutting method controlled by a computer.
The embodiment of the invention as described in more detail hereinafter
provides a modular staircase framework which can be assembled in sections and
which can be inexpensively manufactured (in mass quantities) by cutting
components
of the framework out of sheet metal. The components, typically which are
substantially flat, may be more easily packaged and shipped across large
distances
including international shipping. Using the computer-controlled cutting method
affords
feasible fabrication of parts for curved staircases in which a majority of the
parts may
have unique dimensions. In a situation where a plurality of parts have
dimensions
which are unique to a few of the parts, fabricating the plurality of parts by
casting or
using molds is not as practical as using a computerized cutting tool which is
configured to accommodate differences from part to part. Furthermore, a
staircase
design can be easily adjusted to fit a height between levels by adjusting
corresponding plate dimensions. Also, a plurality of shapes may be
accommodated by
the computerized cutting tool. In addition, the computer controlled aspect of
the
cutting method affords precision in meeting building codes for staircases.
Design work
for the modular staircase framework, which may be done in computer programs
including AutoCAD, allows the design to be exported into programs like
SolidWorks
for load testing simulations and other simulated structural assessments. In
general,
the embodiment of the invention affords centuries of staircase building
knowledge to
be incorporated and preserved using modern technology including the computer
and
software programs such as AutoCAD.
In one instance, the cutting method comprises laser cutting. In another
instance, the cutting method comprises plasma cutting.
Preferably, the coupling element is overlapping the receiving element
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along a planar surface of the at least one of the first or second stringer
plates of the
first step.
Preferably, the receiving element comprises at least one hole. When the
receiving element comprises the at least one hole, it is preferred that said
at least one
5 hole comprises a plurality of holes along the first upright edge.
Preferably, the coupling element comprises at least one tab projecting
from the second upright edge of said at least one of the first or second
stringer plates
of the second step, said at least one tab being arranged for overlapping the
receiving
element. When the coupling element comprises the at least one tab, it is
preferred
that said at least one tab comprises a plurality of tabs along the second
upright edge.
Preferably, the coupling element is bent at an angle from a planar
surface of said at least one of the first or second stringer plates of the
second step for
introducing a curve in the staircase.
Preferably, the coupling element is integral with said at least one of the
first or second stringer plates of the second step.
Preferably, each one of the first and second stringer plates comprises a
top edge spanning between the first and second upright edges thereof, and at
least
one of the first or second stringer plates includes a tread mounting element
at or
adjacent the top edge thereof. In one instance, the tread mounting element
comprises
at least one flange along the top edge that is arranged for coupling the tread
plate
thereto. When the tread mounting element comprises the at least one flange,
the at
least one flange is optionally a plurality of flanges along the top edge. In
another
instance, the tread mounting element comprises at least one projecting element
projecting from the top edge that is arranged for riveting the tread plate.
When the
tread mounting element comprises the at least one projecting element, it is
preferable
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that the at least one projecting element comprises a plurality of projecting
elements
along the top edge.
Preferably, the first stringer plate has a first plate width measured
between the first and second upright edges thereof and the second stringer
plate has
a second plate width measured between the first and second upright edges
thereof,
and when the first and second stringers are curved for creating a curved
staircase, the
first plate width of at least one of the first stringer plates is different
from the first plate
width of at least another one of the first stringer plates and the second
plate width of
at least one of the second stringer plates is different from the second plate
width of at
least another one of the second stringer plates.
Preferably, at least one of the steps further comprises a riser plate
spanning between the first and second stringer plates thereof, the riser plate
being
arranged in an upright orientation between the first and second stringer
plates. Each
tread plate comprises opposing inner and outer edges spanning between
laterally
opposing side edges of the tread plate, the inner edge being arranged closer
to the
second upright edges of the first and second stringer plates of each step than
to the
first upright edges thereof and the outer edge being arranged closer to the
first upright
edges of the first and second stringer plates of each step than to the second
upright
edges thereof. The riser plate comprises opposing top and bottom edges
spanning
between laterally opposing upright side edges, the top and bottom edges and
the
upright side edges collectively defining an outer periphery of the riser
plate.
Preferably, the riser plate further comprises a plurality of projecting
elements along
the outer periphery that are arranged for riveting to at least one of the
tread plates or
to the first and second stringer plates of said at least one of the steps. It
is preferred
that the projecting elements along the outer periphery comprises projecting
elements
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along the top edge of the riser plate for riveting to said at least one of the
tread plates,
and said at least one of the tread plates further comprises a plurality of
holes along
the outer edge arranged to receive the projecting elements of the riser plate
therein. It
is also preferred that at least one of the tread plates further comprises a
plurality of
projecting elements along the inner or outer edge that are arranged for
riveting to the
riser plate. Preferably, the projecting elements along the inner or outer edge
of the
tread plate comprise projecting elements along the inner edge thereof.
According to a second aspect of the invention there is provided a
modular staircase framework kit for assembly in sections comprising:
a plurality of first stringer plates;
a plurality of second stringer plates arranged to be laterally opposite the
first stringer plates;
wherein the first and second stringer plates have opposing first and
second edges;
wherein the first and second stringer plates are arranged to be
substantially upright and substantially parallel to one another;
a plurality of tread plates arranged to span between the first and second
stringer plates in a horizontal orientation;
wherein the first stringer plates are arranged to collectively define a first
stringer and the second stringer plates of the steps are arranged to
collectively define
a second stringer;
at least one of the first or second stringer plates comprising holes along
the first edge thereof;
at least another one of the first or second stringer plates comprising tabs
projecting from the second upright edge thereof for coupling to the holes of
said at
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least one of the first or second stringer plates;
wherein the first and second stringer plates and the tread plates are
fabricated from sheet metal using a cutting method controlled by a computer.
Preferably, the first and second stringer plates and the tread plates are
arranged to accept and incorporate thereon finishing materials including wood,
cork,
marble, glass, granite, and laminate that can sized and shaped using the first
and
second stringer plates and the tread plates as templates therefor. The
finishing
material may be sized and shaped using a cutting method comprising one of
manual
cutting, e.g., using a hand tool like a router, and computer controlled
cutting.
Optionally, the first and second stringer plates comprise ornate designs
therein that
are cut out from the plates using the cutting method. The framework may be
used in
internal or external applications.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention will now be described in
conjunction with the accompanying drawings in which:
Figure 1 is a schematic illustration in top plan view of a grand staircase
assembled from the modular staircase framework.
Figure 2 is an exploded view of a three adjacent steps of the modular
staircase framework.
Figure 3 is an exploded view of a first two of the three adjacent steps in
Figure 2 showing two embodiments of the tread mounting element of the stringer
plates.
Figure 4A is a side elevation view of the stringer plates of two adjacent
steps having first edge lengths `X1' and second edge lengths 'Y'.
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Figure 4B is a side elevation view of the stringer plates of two adjacent
steps, as in Figure 4A, having first edge lengths `X2' and second edge lengths
'V'
where X2 > X1.
Figure 5 is a schematic illustration in top plan view of a series of
assembled steps of the staircase framework, including a topmost step, with
some
components omitted for clarity of illustration.
Figure 6 is a schematic illustration in front elevation view of a series of
assembled steps of the staircase framework, including the topmost step, with
some
components omitted for clarity of illustration.
Figure 7 is a schematic illustration in side elevation view of a series of
assembled steps with some components omitted for clarity of illustration.
Figure 8 is an exploded view of another two adjacent steps more clearly
illustrating coupling between tread plates and riser plates.
Figure 9 is a side elevation view of an embodiment of the modular
staircase framework having extension plates.
In the drawings like characters of reference indicate corresponding parts
in the different figures.
DETAILED DESCRIPTION
Referring to the accompanying figures, there is illustrated a modular
staircase framework generally indicated by reference numeral 10 that is
assembled in
sections, generally one step of the staircase framework at a time. The modular
staircase framework is especially suited for curved staircases or grand
staircases.
Curved staircases generally comprise stringers which have constant curvature;
that is,
for a generally longitudinal staircase which curves, a first stringer thereof
is concave
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while an opposing second stringer is convex so that both stringers comprise
curvature
in one lateral direction. In contrast, grand staircases comprise at least one
stringer,
generally an outer one of the stringers, which comprises curvature in more
than one
lateral direction so that the outer one of the stringers has convex and
concave
5 portions (more clearly seen in FIG. 1). Note that the modular staircase
framework 10
may also be used for rectilinear staircases.
The modular staircase framework spans between an upper level U and
a lower level L. A vertical height between upper and lower levels may vary.
The
modular staircase framework has an upper end at a topmost step 12 of the
staircase
10 framework and a lower end at a bottommost step 14 of the staircase
framework.
The framework comprises a plurality of steps 16. The number of steps
depends on two primary factors: (i) the vertical height between upper and
lower
levels; and (ii) a predetermined range for vertical spacing between treads of
adjacent
steps that is allowed by building code.
Each step has a pair of stringer plates 18. The pair of stringer plates
comprises a first stringer plate 18A and a second stringer plate 18B which is
laterally
opposite the first stringer plate and spaced therefrom. The stringer plates of
each step
are oriented substantially upright and are substantially parallel to one
another. When
coupled together, the stringer plates collectively define respective
stringers. More
specifically, the first stringer plates of the steps collectively define a
first stringer 20A
which for purposes of this description defines an inner radius of the curved
staircase.
Similarly, the second stringer plates of the steps collectively define a
second stringer
20B, and for the purposes of this description the second stringer defines an
outer
radius of the curved staircase. Aside from placement within the framework,
general
shape of the first and second stringer plates is substantially similar and
consequently
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discussed simultaneously below by reference to each stringer plate.
Generally speaking, each stringer plate 18 is substantially planar. Each
stringer plate has opposing first 22 and second 24 edges. A top edge 26 of
each
stringer plate spans between the first and second edges at top ends thereof.
The top
edge meets each one of the first and second edges at right angles such that
the first
and second edges are substantially parallel to one another. A bottom edge 28
is
opposite the top edge. The bottom edge spans between bottom ends of the first
and
second edges and is curved as an aesthetic feature of the stringer plates. The
first
edge is longer than the second edge such that the bottom edge extends
generally
downwardly and forwardly from the second edge to the first edge when the
stringer
plates are oriented substantially upright. Furthermore, within each pair of
adjacent
steps, the stringer plates of each respective stringer are aligned so that the
first edge
of the stringer plate of a first step is adjacent the second edge of the
stringer plate of
an adjacent step which is generally lower than the first step. As such, the
first edge is
longer than the second edge in order to accommodate coupling of the stringer
plate of
the first step to the stringer plate of the adjacent step. Also, lengths of
all first edges of
the stringer plates are substantially the same and lengths of all second edges
of the
stringer plates are substantially the same so as to maintain consistent
vertical spacing
between the treads of adjacent steps. When the stringer plates are coupled in
the
respective stringers, the bottom edges of adjacent stringer plates are
substantially
flush so as to comprise a smooth, continuous, wavy contour along a bottom edge
of
the stringer.
Each stringer plate also has a plate width 'W' measured between the
first and second edges, more clearly shown in FIG. 2. Depending on location of
the
particular stringer plate within the framework, the plate width of each
stringer plate
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may be different in order to properly form the curve of the staircase.
However,
generally when considering each respective stringer the plate width of at
least one
stringer plate is different from the plate width of at least another one of
the stringer
plates in the framework for the curved staircase. For example, as more clearly
shown
in FIG. 5, the stringer plates of adjacent steps may have different widths W1
and W2
where W2 > W1 in order to achieve the proper curvature of the staircase.
Within each pair of adjacent steps, each stringer plate of the first step
comprises a plurality of holes 30 spaced along the first edge thereof. The
holes
collectively define a receiving element of the stringer plate.
Further to the receiving elements of the first step, each stringer plate of
a second step, which defines the adjacent step of the pair of adjacent steps,
comprises a plurality of tabs 32 projecting from the second edge of each
stringer
plate. The tabs collectively define a coupling element of the stringer plate.
Furthermore, the tabs are integral with the stringer plate. Each one of the
tabs has an
outer periphery which is convex. Each one of the tabs has a hole therein that
is
aligned with a corresponding one of the holes in the stringer plate of the
first step in
an overlapping configuration. More specifically, the tabs of the stringer
plate of the
second step overlap a part of an outer planar surface of the stringer plate of
the first
step. Since the stringer plate of the first step may be angled away from the
stringer
plate of the second step, the tabs may be bent relative to the stringer plate
of the
second step at an angle away from a plane of the stringer plate for properly
forming
the curve when coupling adjacent stringer plates, as more clearly shown in
FIG. 5
where the coupling element 32 is parallel to the plane of the immediately
previous
step at its receiving element 30 (which is typically coplanar with a main
portion of the
stringer plate). As such, each stringer plate is substantially rigid so that
it can bear
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weight of a load thereon; furthermore, each stringer plate which has tabs is
substantially flexible at the tabs so that the tabs may be bent as described.
It is important to note that a majority of the stringer plates (i.e., both the
first and second stringer plates) comprise both the receiving element and the
coupling
element because the majority of the stringer plates belong to two pairs of
adjacent
steps. In contrast, the stringer plates which form part of the topmost step 12
may only
have the receiving elements for coupling to the adjacent step; in place of the
coupling
elements along the second edge 24, the stringer plates forming the topmost
step may
have another coupling element at or adjacent the second edges of the stringer
plates
for coupling to a structural member, such as a joist J, of the upper level U.
In the
illustrated embodiment, the another coupling element of the topmost step
comprises a
joist coupling element 34 which is a planar flange with the tabs, like those
which
define the coupling element of remaining ones of the stringer plates,
projecting
therefrom in the plane of the flange. The flange is an extension of the second
edge of
the stringer plates of the topmost step and consequently spans a full length
of the
second edge. The joist coupling element is bent relative to the stringer
plate, as the
tabs of the remaining ones of the stringer plates, though at an angle away
from the
plane of the stringer plate that is generally greater than the angle between
the tabs
and the plane of one of the remaining stringer plates. Similarly to the
topmost step,
the stringer plates forming part of the bottommost step 14 may only have the
coupling
elements for coupling to the step adjacent the bottommost step; in place of
the
receiving elements, the stringer plates forming the bottommost step may have a
fastening element at or adjacent the first edges of the stringer plates for
coupling to
the lower level.
Further to the stringer plates, each step of the modular staircase
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framework also comprises a tread plate 36. The tread plate spans between
opposing
stringer plates of each step. The tread plate is oriented substantially
horizontally. The
tread plate is positioned on top of the stringer plates so as to lie flush
along the top
edges 26 thereof. Side edges 38 of the tread plate extend outwardly beyond the
stringer plates in the illustrated embodiment.
Each tread plate is substantially planar. Each tread plate has an inner
edge 40 which spans between the side edges of the tread plate. The inner edge
is
generally over the second edges 24 of the stringer plates of a respective
step. An
outer edge 42 of the tread plate is opposite the inner edge thereof so as to
be
generally over the first edges 22 of the stringer plates of the respective
step. The
inner edge may be arced inwardly, in a direction generally towards the outer
edge so
as to be concave relative to the side edges of the tread plate, and the outer
edges
may be arced outwardly, in a direction generally away from the inner edge so
as to be
convex relative to the side edges. In the illustrated embodiment, the outer
edge of the
tread plate extends outwardly beyond the first edges of the stringer plates so
as to be
over the tread plate of the adjacent step. Additionally, the side edges of
each tread
plate may have different lengths as the inner and outer radii of the curved
staircase
are different.
Turning back now to the stringer plates, each stringer plate has a tread
mounting element at the top edge for mounting the tread plate thereto. In the
illustrated embodiment, the tread mounting element comprises a plurality of
rivets 44
projecting from the top edge at spaced locations along the top edge. The
rivets define
a projecting element. As the stringer plates may have different plate widths,
spacing
between the rivets of each stringer plate may vary from plate to plate;
however,
spacing of each one of the rivets inwardly from an end of the top edge is
substantially
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equal for the stringer plates. Further to the rivets on the stringer plates,
the tread
plates have holes 46 spaced inwardly from the side edges thereof which are
aligned
with the rivets of the stringer plates for accepting the rivets therethough.
To accommodate the vertical spacing between tread plates of adjacent
5 steps that may vary between implementations of the modular staircase
framework,
generally a first edge length 'X' of the first edge 22 of each stringer plate
is adjusted.
The first edge length is measured along the first edge between the top 26 and
bottom
edges 28. As more clearly shown in FIG. 4, the first edge length is increased
from 'X,'
to `X2' (Le., X2 > X1) when the vertical spacing is larger, and conversely the
first edge
10 length is decreased when the vertical spacing is smaller. Since a second
edge length
'Y', which is measured along the second edge 24 generally between the top 26
and
bottom 28 edges, is maintained constant as the first edge length is changed to
accommodate the vertical spacing, spacing of each one of the holes 30 of the
stringer
plate measured from the bottom edge 28 in a direction along the first edge 22
is
15 maintained constant between implementations of the modular staircase
framework.
Each step may further include a riser plate 48. The riser plate generally
increases structural strength of the staircase framework. The riser plate
spans
between the first 18A and second 18B stringer plates in an upright
orientation. Each
riser plate has opposing top 50 and bottom 52 edges and opposing inner and
outer
= 20 surfaces 53A and 53B. In the illustrated embodiment, the riser
plate overlaps the first
edges 22 of the stringer plates so that the inner surface 53A of the riser
plate engages
the first edges, as more clearly shown in FIG. 6. Also, as more clearly shown
in FIG.
7, the top edge 50 of the riser plate is substantially flush with a bottom
surface 37A of
the tread plate 36 which is over the riser plate. Furthermore, the outer
surface 53B of
the riser plate at a location along the bottom edge 52 thereof engages the
inner edge
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40 of the tread plate of a lower step with the bottom edge 52 of the riser
plate
engaging the top edge 26 of the stringer plate thereunder.
Each riser plate defines a plane prior to being flexed across the stringer
plates so as to be arced therebetvveen. The riser plates are substantially
flexible so
that the riser plates can be arced across the steps. As more clearly shown in
FIG. 7,
each riser plate comprises a plurality of rivets 54 spaced along the top edge
50 of the
riser plate for fastening to the tread plate 36 above the riser plate. The
rivets project
from the top edge in the plane of the riser plate. Accordingly, each tread
plate has a
plurality of holes 56 spaced along the outer edge 42 of each tread plate which
are
arranged to receive the rivets of the riser plate therethrough. The holes
along the
outer edge of the tread plate are spaced inwardly away from the outer edge so
as to
lie along a contour where the riser plate meets the tread plate along the top
edge 50
of the riser plate.
Each riser plate joining tread plates of adjacent steps also has holes 58
spaced along the bottom edge 52 thereof. Accordingly, the tread plate of every
step
excluding the topmost step has a plurality of rivets 60 projecting from and
spaced
along the inner edge 40 of the tread plate. The holes 58 along the bottom edge
52 of
the riser plate are arranged to receive the rivets 60 of the tread plate
therethrough.
The stringer plates 18, tread plates 36, and riser plates 48 are fabricated
from flat sheet metal which is cut into appropriate shapes and to have all
necessary
components (e.g., the tabs, holes, and rivets) using a cutting method
controlled by a
computer. The cutting method comprises laser cutting in the illustrated
embodiment;
in other embodiments, the cutting method comprises plasma cutting. Generally,
implementation of the computer to control the cutting of the sheet metal makes
fabrication of all the plates more feasible as opposed to casting the plates,
especially
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when each stringer plate may have a different plate width W' and when the
first edge
length of the stringer plates may be adjusted in order to accommodate the
vertical
height between upper and lower levels of the particular implementation for
which the
dimensions of the modular staircase framework were designed. Ornate designs
may
also be cut into the plates. In order to meet maximum load criteria, thicker
(i.e., higher
gauge) sheet metal may be used or riser plates may be fabricated in order to
strengthen the framework. As such, the computer program manages the
fabrication all
of the components for the staircase. Each one of the plates is catalogued by
the
computer program and labelled during the cutting of the plates. An end result
of the
fabrication of the framework is generally a plurality of flat plates which can
be
packaged and shipped to the customer, where the staircase is then assembled
from
the plurality of plates on-site at an intended building location. Note that in
the
illustrated embodiment the tabs of the stringer plates are not bent as part of
the
fabrication/manufacturing process, i.e., during a time between cutting the
stringer
plates and assembly of the framework.
In order to assemble the staircase framework, an installer generally
begins with the topmost step 12. The stringer plates 18 are typically mounted
to a joist
of the upper level. Then, the tread plate 36 is mounted across the stringer
plates so
as to lie horizontally flush along the top edges 26 thereof as in the
illustrated
embodiment. Alignment of the tread mounting elements of the stringer plates
with the
holes 46 along the side edges 38 of the tread plate may necessitate bending of
the
stringer plates at the coupling elements thereof. As such, this alignment of
the tread
mounting elements of the stringer plates with the holes 46 along the side
edges of the
tread plate, for each step, generally dictates proper formation of the
curvature of the
stringers of the framework 10.
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After the tread plate of the topmost step is mounted, the riser plate 48 is
also installed, if present. During installation of the riser plate, the riser
plate is arced
across the stringer plates as the rivets 54 along the top edge 50 of the riser
plate are
aligned with and inserted into the holes 56 along the outer edge 42 of the
tread plate.
That is, the riser plate takes on its flexed shape primarily as a result of
fitting the rivets
54 of the riser plate into the holes 56 of the tread plate.
After installing the topmost step, the installer continues with the adjacent
step, installing each adjacent step one plate at a time and typically starting
installation
of the adjacent step with attachment of the stringer plates to the stringer
plates of an
upper step via bolts. Bolting of the stringer plates to those of the upper
step is
followed by fastening of the tread and riser plates. Installation of the tread
plate
involves inserting the rivets 60 along the inner edge 40 of the tread plate
into the
holes 58 of the riser plate of the upper step.
Once assembled, the modular staircase framework 10 of the illustrated
embodiment defines a frame of a freestanding staircase. The tread plates may
be
detached after assembly of the modular staircase framework for sizing and
shaping
finishing materials to be installed on the tread plates using the tread plates
as
templates therefor.
It will be appreciated that projection of the tread plate's outer edge 42
beyond the riser plate 48 thereunder may afford sufficient space for this
riser plate,
which meets the respective tread plate 36 at its bottom surface 37A, to
receive a
finishing material thereon of appropriate thickness without then protruding
beyond the
tread plate thereover.
It is important to recognize that since the fabrication process involves
cutting of the plates, free of any bending of any of the coupling elements of
the
CA 02920585 2016-02-11
19
stringer plates, it is possible to assemble a mirrored version of the
staircase
framework which curves in an opposite manner from the initial design by
interchanging positions of the first and second stringer plates of each step
and
mounting the tread plates and the riser plates reversely.
In one other embodiment of the present invention, the tread mounting
element is a pair of flanges 62 that are bent at substantially right angles to
the stringer
plate.
In another embodiment shown in FIG. 9, the framework also includes a
plurality of extension plates 64. Each step having stringer plates which are
raised from
the lower level has a pair of the extension plates. Each extension plate is
coupled to a
stringer plate 18 so as to extend downwardly therefrom to the lower level. As
such,
the extension plate spans vertically between a top edge 66 thereof, which is
curved to
match the bottom edge 28 of the stringer plate to which the extension plate is
attached, and a bottom edge 68 of the extension plate that is generally
substantially
flush with the lower level. Opposing side edges 70 of the extension plates are
parallel
to one another and typically span a majority of a vertical length of the
extension
plates. Also, ornate designs may be cut into the extension plates. In general,
the
extension plates provide support to the stringers and improve the structural
strength
of the entire staircase framework. Furthermore, the extension plates along
each one
of the stringers collectively define a wall.
In yet another embodiment shown, a pair of substantially identical
staircase frameworks are arranged one over top of another. A first one of the
pair of
staircase frameworks joins a first level and a second level adjacent thereto
and over
the first level. A second one of the pair of staircase frameworks joins the
second level
and a third level adjacent thereto and over the second level. A plurality of
elongate
CA 02920585 2016-02-11
structural members span vertically between the staircase frameworks along at
least
one of the stringers thereof. The elongate structural members, which may
comprise
studs, are coupled to the stringers along outer surfaces thereof along joints
of the
stringers which are defined by the coupling element of one stringer plate
overlapping
5 the receiving element of an adjacent stringer plate. The bolts for
coupling the adjacent
stringer plates may also be driven through the studs so that one set of bolts
couples
adjacent stringer plates and the stud to the stringer at the joint. The studs
collectively
define a wall framework upon which panels may be mounted for making a wall.
In yet further embodiments in which ornate designs are cut into the riser
10 plates, lighting may be added loran aesthetically pleasing effect.
Further alternative embodiments may include hand rail jigs which are
also designed and fabricated by the computer program like the steps of the
staircase.
Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same
made,
15 it is intended that all matter contained in the accompanying
specification shall be
interpreted as illustrative only and not in a limiting sense.
