U.S. patent number 3,929,376 [Application Number 05/502,496] was granted by the patent office on 1975-12-30 for metal chair.
Invention is credited to Richard Kates.
United States Patent |
3,929,376 |
Kates |
December 30, 1975 |
Metal chair
Abstract
An improved lightweight metal chair having a number of
structural enhancements is disclosed. The flexural rigidity of the
frame of the chair seat is enhanced by counters which develop
tensile forces to resist flexure incident to the loading of the
chair. The legs of the chair are connected to the frame of the seat
by gussets which supportingly embrace and grip one or more members
of the frame of the seat. The structural interface between the
frames of the seat and back of the chair include telescopic
connections in which the male member depends from the frame of the
seat while the female member is associated with the frame of the
back. Rigid arms interconnect the frames of the seat and back. The
chair is easily disassembled for compact storage.
Inventors: |
Kates; Richard (New York,
NY) |
Family
ID: |
23998105 |
Appl.
No.: |
05/502,496 |
Filed: |
September 3, 1974 |
Current U.S.
Class: |
297/445.1;
248/188; D6/376 |
Current CPC
Class: |
A47C
5/04 (20130101) |
Current International
Class: |
A47C
5/04 (20060101); A47C 5/00 (20060101); A47C
001/12 () |
Field of
Search: |
;297/445,440,443,450,460,421,411,449 ;5/292,301,304,310
;108/156,155,154,153 ;126/34R ;248/188 ;D6/50,52,79 ;211/181,177
;182/178,185 ;52/693,695 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McCall; James T.
Attorney, Agent or Firm: Burns, Doane, Swecker &
Mathis
Claims
What is claimed is:
1. A metal chair comrising:
a seat frame forming a seat portion of the chair, said seat frame
including
a front portion,
a back portion, and
side portions interconnecting said front and back portions,
a plurality of support legs depending from said frame, and
countering means connected directly to one of said frame portions
for resisting flexture of said frame in response to the application
of a load thereupon, said countering means including
a tensile rod whose ends terminate short of said support legs,
and
plural spacer portions for connecting said tensile rod directly to
said one frame portion exclusive of connection to said support legs
to space said tensile rod below said one frame portion in the
region of maximum bending thereof, so that downward flexure of said
front frame portion develops tensile forces in said tensile rod
which resist such downward flexure.
2. A chair according to claim 1 wherein said one seat frame portion
comprises said front frame portion; said tensile rod extending
parallel to said seat front frame portion.
3. A chair according to claim 2 wherein said spacer portions are
formed by integral curved extensions of said tensile rod.
4. A chair according to claim 3 wherein each of said integral
curved extensions comprises:
a first section that curves upwardly from an end of said tensile
rod into welded connection with said front frame portion;
a second section which extends downwardly toward said tensile rod,
and
a third section which curves upwardly into welded connection with
said front frame portion.
5. A chair according to claim 4 wherein said third sections of said
spacer portions are welded to one another.
6. A chair according to claim 1 wherein said front, back, and side
frame portions are formed from angle members having leg sections
forming a generally right angle in cross section, one leg section
being directed horizontally inward toward the interior of said seat
frame and the other leg section being directed vertically downward;
said angle members being arranged to form a rectangle having four
corners; a plurality of gusseting means disposed at each corner for
connecting each support leg to a pair of intersecting ones of said
frame portions; said gusseting means comprising:
a pair of generally vertical gusset plate portions extending
transversely to one another and intersecting to form a vertical
interior angle,
a pair of horizontal top flanges mounted at upper ends of said
vertical plate portions and extending across segments of said
horizontal leg sections of said pair of intersecting frame
portions,
a pair of bottom flanges connected to said vertical plate portions;
said bottom flanges including:
generally horizontal support portions disposed below said
horizontal flanges in supporting engagement with the vertical leg
sections of said pair of frame portions, and
generally vertical support portions extending downwardly from said
horizontal support portion and being spaced from one another to
receive a support leg therebetween and to support said support leg
with said support leg being rigidly coupled to said gusset means
and nestingly seated within said vertical interior angle defined by
said vertical plate portions.
7. A metal chair comprising:
a rectangular first frame having front, side, and back frame
portions formed from angle members each having leg sections forming
a generally right angle in cross section, one leg section being
directed vertically downward;
said angle members being arranged to form a rectangle having four
corners;
a plurality of support legs extending downwardly from and
supporting said first frame at the corners thereof; and
a plurality of gusseting means disposed at each corner for
connecting each support leg to a pair of intersecting ones of said
frame portions, said gusseting means comprising:
a pair of generally vertical gusset plate portions extending
transversely to one another and intersecting to form a vertical
interior angle,
a pair of horizontal top flanges mounted at upper ends of said
vertical plate portions and extending across segments of said
horizontal leg sections of said pair of intersecting frame
portions;
a pair of bottom flanges connected to said vertical plate portions,
said bottom flanges including:
generally horizontal support portions disposed below said
horizontal flanges in supporting engagement with the vertical leg
sections of said pair of frame portions, and
generally vertical support portions extending downwardly from said
horizontal support portions and being spaced from one another to
receive a support leg therebetween and to support said support leg
with said support leg being rigidly coupled to said gusset means
and nestingly seated within said vertical interior angle defined by
said vertical plate portions.
8. A metal chair according to claim 7 wherein said gusset means is
secured to said pair of intersecting frame portions by a pair of
threaded fasteners extending through said vertical plate portions
and said vertical leg sections of said frame portions; said support
leg being rectangular in cross section and including a corner being
conformably configured to said vertical interior angle in which it
is nestingly seated.
9. A metal chair according to claim 7 wherein said bottom flanges
each comprise generally arcuate shaped members, with the upper ends
of said arcuate members curving generally horizontally to define
said horizontal support portions, and with the lower ends of said
arcuate members curving generally vertically to define said
vertical support portions.
10. A chair as defined in claim 1 wherein:
said first spacing means interconnect said tensile rod and said
front portion of said seat frame to form a rigid, essentially
triangular lattice therebetween, said lattice being symmetrical
about a generally vertical axis passing through the midpoint of
said front portion of said seat frame.
11. A chair as defined in claim 1 wherein:
said first spacing means interconnect said tensile rod and said
front portion of said seat frame to form a rigid, essentially
rectilinear lattice therebetween, said lattice being symmetrical
about a generally vertical axis passing through the midpoint of
said front portion of said seat frame.
12. A chair as defined in claim 1 further comprising:
a second frame forming a back of said chair against which an
occupant may recline while seated on said seat frame, said second
frame including generally upright members connected to said back
portion of said seat frame and interconnected at the upper ends
thereof by an elongated, top member; and
a plurality of suspending means interconnecting said upright
members, said elongated top members, and said back portion of said
seat frame for suspending said back portion of said seat frame and
transferring at least a portion of the loads exerted on said back
portion of said seat frame, incident to said loading of said chair,
into those of said legs connected to said back portion of said seat
frame, said suspending means comprising:
a first hanger bar interconnected between one of said upright
members and said back portion of said seat frame;
a second hanger bar interconnected between another of said upright
members and said back portion of said seat frame;
a third hanger bar interconnected between said one upright member
and said top member, and
a fourth hanger bar interconnected between said other upright
member and said top member.
13. A chair as defined in claim 12 wherein:
said plurality of suspending bars interconnect said upright
members, said elongated top member, and said back portion of said
seat frame to form a triangular lattice symmetrical about a
generally vertical axis passing through the midpoint of said second
frame.
14. A chair as defined in claim 13 wherein said upright members
include:
terminal upright members each comprising a lateral end of said
second frame and operable to flexurally resist loads imposed on
said second frame; and
intermediate upright members each located between said terminal
uprights and operable to at least partially suspend said back
portion of said first frame when subject to said loading.
15. A chair as defined in claim 13 further comprising:
at least a pair of rigid arms each extending generally upwardly
from a side portion of said first frame to a point intermediate the
ends of a terminal upright member of said second frame.
16. A chair as defined in claim 4 further comprising:
a slot in said top flange of each of said gusseting means
supporting the intersection of back and side frame portions of said
seat frame, said slot extending diagonally into the angle formed
thereby;
a solid, cylindrical pin rigidly connected to the interior of the
intersection of said vertical leg sections of each pair of said
intersecting side and back portions of said seat frame and
extending upwardly through said slot of each of said gusseting
means; and
a rectangular, second frame forming a back of said chair against
which an occupant may recline while seated on said seat frame, said
second frame including a generally upright members each having a
lower portion telescopable over one of said cylindrical pins to
connect said seat and second frames.
17. A chair as defined in claim 7 wherein:
each support leg supporting said first frame is bent about diagonal
axes to diagonally splay said support leg relative to said
gusseting means and said first frame.
18. A chair as defined in claim 7 further comprising:
a slot in said top flange of each of said gusseting means
supporting the intersection of back and side frame portions of said
first frame, said, slot extending diagonally into said right angle
formed thereby;
a solid, cylindrical pin rigidly connected to the interior of the
intersection of said vertical leg sections of each pair of said
intersecting side and back frame portions of said first frame and
extending upwardly through said slot of each of said gusseting
means; and
a rectangular, second frame forming a back of said chair against
which an occupant may recline while seated on said first frame,
said second frame including generally upright members each having a
lower portion telescopable over one of said cylindrical pins to
connect said first and second frames.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to a metal chair which may be used
in and around the home. More particularly, the invention relates to
a metal chair which is sturdy, compact, lightweight, and which can
be readily assembled and disassembled, but which nonetheless can be
efficiently and inexpensively manufactured.
In recent years, the public has devoted increased attention and
time to the out-of-doors (e.g., patio) living. The increased
exposure of the general population to the out-of-doors has
developed a considerable demand for outdoor furniture of various
types including chairs for both single and plural occupants. In
order to avoid problems caused by mildew, decay, and exposure to
the elements, this furniture is usually fabricated entirely or
principally of metal. Metal construction and the character of the
use of the furniture often present a number of problems.
Outdoor furniture may be subject to heavy use and as a consequence,
may often be vulnerable to failure. A chair seat frame, for
instance, must be sufficiently flexurally rigid to sustain the
weight of the occupants. This problem is considerably exacerbated
in the case of a chair for plural occupants since the portion of
the frame which undergoes the principal loading by the seated
occupants is considerably longer in a chair for plural occupants
than in the case of a chair for a single occupant. For this reason,
this portion of the frame of the seat is subject to bending moments
of greater magnitude. The magnitude of the bending moments, if
sufficiently large, can cause undue deflection and/or yielding of
what is optimally a rather slender structural member. Undue
deflection and/or yielding of the frame of the seat can be avoided
by either increasing the size of the structural member or by adding
a leg intermediate the ends thereof to provide support. Both
approaches clearly increase the cost, weight, bulk, ad complexity
of such an article of furniture.
Another approach to problems connected with the flexural
capabilities of the frame of the seat has been to employ a
compression member to support the seat of the chair from below.
These compression members are themselves vulnerable to buckling. To
render such a member structurally adequate, it may be necessary to
increase the size thereof. This remedy is undesirable for the
reasons suggested earlier.
A further approach to the problem of the flexural rigidity of the
frame of the seat of a chair which has been proposed employs an
arcuate member to suspend the frame of the seat from the back of
the chair to thereby transfer load exerted on the seat into the
legs of the chair. An arcuate member, of course, is quite subject
to flexure and associated stress concentrations and for this reason
is inefficient as a structural member. To be effective, such a
member must of necessity be unduly heavy. An arcuate member also
may be costly to manufacture.
In summary, it would be desirable, if the chair seat frame
undergoing the principal loading could be stiffened against flexure
without adding significantly to the materials or labor required to
fabricate the frame.
Not only should the chair seat frame be sufficiently flexurally
rigid to sustain the usual loads, but the structural interface
between the seat of the chair and the back thereof must be capable
of resisting forces exerted as an occupant leans back or reclines
against the back of the chair. This problem may be aggravated by
the fact that the back of a chair is often inclined relative to the
frame of the seat in a manner which results in a relatively complex
connection. Clearly, the strengthening of such a connection is
potentially costly in terms of materials and labor and may have an
adverse effect on the desirable chair weight, bulk, and
complexity.
Several devices of the prior art employ telescopic connections to
form the structural interface between frames forming the seat and
back of the chair. These telescopic connections generally employ
female members rigidly connected to the frame of the seat and solid
cylindrical male members rigidly connected to and extending from
the frame of the back of the chair. Arrangements of this type are
commonly heavily reinforced and cumbersome since the connection
must be capable of resisting the tendency of the male member to
buckle and the tendency of the female member to tear or collapse.
Such a configuration is thus not only vulnerable to failure but is
also inefficient in terms of labor and materials. Indeed, the solid
cylindrical character of the male member is frequently extended to
the frame of the back as a whole and may for this reason also
increase the weight of the chair.
Ah additional structural requirement resides in the need for the
legs of the chair to form a stable base securely connected with the
frame of the chair. It has been proposed in this connection to
enlarge the base of the chair. This can be done in various ways.
For example, it has been proposed to enlarge the frame of the seat
from which the legs depend. This approach, however, adds to the
amount of materials required to fabricate the frame of the seat and
may simply add useless capacity to the chair. The base may also be
enlarged by splaying the legs of the chair. Splaying may render the
connection of the legs to the chair vulnerable to failure and may
therefore require that the connection be strengthened.
In some instances, chairs appearing in the prior art may employ
flanges connected to each leg and the frame of the chair to enhance
the strength of the connection therebetween. In most cases, the
flanges of these arrangements are simply bolted in place and are
not otherwise secured to the frame of the chair. For this reason,
connections of this type may not afford sufficient structural
contact to ensure solid connections between a chair and the
associated legs. In those cases in which it is desirable to enlarge
the base of the chair by splaying the legs, the flanges may be
highly vulnerable to flexural failure and thus may be quite
unsuitable. These arrangements may also be troublesome to
manufacture since the leg may not be amenable to quick and accurate
orientation.
It can be appreciated from the preceding discussion that outdoor
furniture of the prior art which is formed of components which are
sturdy may as a result be bulky and heavy in weight. The bulk and
weight of this furniture often detracts from its more widespread
use since most modern homes and apartments and the recreational
areas associated therewith tend to be rather small. As a
consequence, furniture used in and around such dwellings must not
only be sturdy, but should be compact and light as well.
It is also desirable for outdoor metal furniture to be readily
assembled and disassembled. Outdoor furniture is commonly shipped
in disassembled form for assembly by the ultimate purchaser.
Storage of these articles is also enhanced if the articles are
easily disassembled into compact individual components. Since many
people lack the requisite mechanical skill to assemble any but the
most simple structure, it is particularly desirable that an article
of outdoor furniture should be fabricated such that it can be
readily assembled and disassembled by a person who is mechanically
unskilled.
The problems suggested in the preceding, while not exhaustive, are
among many which may tend to reduce the effectiveness and
desirability of various structural features of metal furniture,
particularly metal chairs. Other noteworthy problems may also
exist; however, those presented in the discussion above should be
sufficient to demonstrate that metal chairs appearing in the prior
art have not been entirely satisfactory, particularly with regard
to structural adequacy, compactness, weight, ease of assembly and
disassembly, and cost.
OBJECTS AND SUMMARY OF THE PREFERRED FORMS OF THE INVENTION
In light of the foregoing, it is therefore a general object of the
invention to provide a novel chair intended to obviate or minimize
problems of the type noted in the preceding.
It is a particular object of the invention to provide a chair,
having a frame forming the seat thereof which is sufficiently
flexurally rigid, without significantly adding to the materials or
labor required to fabricate the chair and without increasing the
weight or cost or reducing the compactness thereof.
It is another object of the invention to provide a chair having a
secure connection between each leg and the frame of the chair
capable of sustaining bending moments and shear forces due to the
loading of the chair.
It is still another object of the invention to provide a novel
chair wherein each leg can be splayed and the connection between
the leg and the frame are configured so that the splay of the leg
can be quickly and accurately oriented during construction relative
to the frame of the chair.
It is yet still another object of the invention to provide a novel
chair wherein the structural interface between the frames forming
the seat and back of the chair is simple and structurally capable
of sustaining loads imposed as an occupant rests or reclines
against the back of the chair.
It is a further object of the invention to provide a chair which is
sturdy, and yet sufficiently light in weight that it can be readily
carried from place to place and sufficiently compact that it can be
used in and around a modern home.
It is still a further object of the invention to provide a chair
which can be disassembled to the degree that the components can be
packaged or stored in a relatively small, flat area and yet readily
assembled and subsequently disassembled by a person who is
mechanically unskilled.
It is yet still a further object of the invention to provide a
chair which can be manufactured in a manner that makes efficient
use of the materials and labor required for construction.
A novel metal chair according to one aspect of the invention
includes a frame forming the seat thereof. The frame of the seat
has front, side, and back portions and legs depending therefrom. A
counter vertically spaced below the front portion of the frame
develops tensile forces and thereby assists in resisting flexure of
the front portion of the frame incident to the loading of the chair
by one or more occupants.
According to another aspect of the invention, another frame forms
the back of the chair and includes generally upright members
connected to the back of the seat frame. The upright members are
interconnected at the upper ends by an elongated top member. A
plurality of suspending counters interconnect the upright members,
the elongated top members, and the back portion of the frame
forming the seat of the chair. These suspending counters suspend
the back portion of the frame of the seat and transfer loads
exerted thereon into those of the legs connected to the back
portion of the frame forming the seat.
According to a further aspect of the invention, the frame forming
the seat of the chair is constructed of members each forming a
generally right angle in cross-section. A plurality of legs are
employed to support this frame. Gussets configured to supportingly
embrace and grip one or more members forming the frame of the seat
connect the legs to the chair.
According to still another aspect of the invention, a slot is
formed in the gussets connecting the legs to the intersection of
members forming the back and side portions of the frame forming the
seat of the chair. A solid cylindrical pin ridigly connected to the
frame forming the seat of the chair extends upwardly through this
slot and receives thereover in telescoping relation the lower ends
of upright members forming the frame of the back of the chair.
THE DRAWINGS
Other objects and advantages of the present invention will become
apparent with reference to the detailed description to follow of a
preferred embodiment thereof wherein like reference numerals have
been applied to like elements and in which:
FIG. 1 illustrates a perspective view of an embodiment of the
invention intended to support a single occupant;
FIG. 2 illustrates a perspective view of an alternative embodiment
of the invention intended to support plural occupants;
FIG. 3 illustrates a fragmentary view in side elevation of the
invention showing a portion of the structural interface between the
frames forming the back and seat of the chair as well as the
connection of a leg and an arm to the chair;
FIG. 4 illustrates a fragmentary, sectional view taken along lines
4--4 of FIG. 3;
FIG. 5 illustrates a fragmentary, sectional view taken along lines
5--5 of FIG. 3;
FIG. 6 illustrates a sectional view taken along the lines 6--6 of
FIG. 5; and
FIG. 7 illustrates a perspective view of a rear corner of the frame
forming the seat of the chair, a rear leg in disassembled relation
therewith, and a portion of the connection between the frames
forming the seat and back of the chair.
DETAILED DESCRIPTION
Referring now to FIGS. 1 and 2 of the drawings, two different
embodiments of the invention can be seen. The most apparent
distinction between these embodiments at this point is that the
chair illustrated in FIG. 1 is intended to accommodate a single
occupant while that illustrated in FIG. 2 is intended to
accommodate plural occupants. Both embodiments have a number of
structural features in common and these features will be pointed
out in the next few paragraphs with the objective of familiarizing
the reader with the general structure of the invention and certain
basic terms. At the outset it should be mentioned that normally the
chairs of both embodiments include cushions which cover most of the
framing. These cushions have been deleted in the drawings so that
the various structural characteristics of the invention can be
clearly illustrated.
Both embodiments employ a first frame 6 which forms the seat of the
chair. The frame of the seat includes front, side, and back
portions 8, 10, and 12, respectively, which are preferably formed
of intersecting leg members each forming a generally right angle in
cross-section, one leg member being vertically oriented while the
other leg member is horizontally oriented and directed inwardly
toward the interior of the frame. It should be evident from the
illustrations that the span between points of vertical support of
the members forming the front and back portions 8 and 12,
respectively, may vary considerably in length.
In both embodiments, a plurality of legs 14 depend from the frame
of the seat 6. These legs may be diagonally splayed relative to the
frame of the seat, that is, the legs are spread diagonally outward
from each corner of the frame of the seat to which they are
connected. The actual connection between each leg 14 and the frame
of the seat 6 is formed by a gusset 16 (described in more detail
hereinbelow) which is rigidly connected to an associated leg and
removably connected to the frame of the seat.
The chairs accommodating both single and plural occupants employ a
second frame 18 which forms a back against which an occupant or
occupants may recline while seated on the frame of the seat 6. The
frame of the back 18 includes upright members 22 which are
connected at their lower ends to the frame of the seat and also
includes an elongated top member 20 which interconnects the upright
members adjacent the upper ends thereof. In each embodiment certain
of the upright members constitute terminal upright members 22 and
each of these members comprise a lateral end of the frame of the
back 18. Each of the terminal upright members 22 preferably forms a
generally right angle in cross-section as may the elongated top
member 20. In the case of the plural occupant embodiment
illustrated in FIG. 2, the frame of the back 18 also includes
intermediate upright members 24 which are disposed between the
terminal upright members 22. These intermediate upright members
interconnect the back portion 12 of the frame of the seat 6 and the
elongated top member 20.
At least a pair of rigid arms 26 are provided in both of the
embodiments illustrated in FIGS. 1 and 2. Each of these arms
extends from connection with a side portion 10 of the frame of the
seat 6 to connection with a terminal upright member 22 of the frame
of the back 18. The connection between a terminal upright member 22
and an arm 26 occurs at a point intermediate the ends of the
terminal upright member.
The front, side, and back portions 8, 10, and 12, respectively, of
the frame of the seat 6 are resiliently interconnected by a web of
strips 28 through coil springs 30. The web formed by the strips and
springs 28 and 30, respectively, serves to transfer loads imposed
on either of the chairs into the frame of the seat 6. Each chair
will, of course, be most commonly loaded by one or more seated
occupants.
The particular distribution of this loading is somewhat uncertain
but should be essentially symmetrical above either of two
intersecting axes of symmetry of the frame of the seat 6 which
coincide with the plane thereof. The distribution of loading due to
seated occupants is probably best approximated by a triangular
distribution, the apex of which occurs at the center of the area in
which the occupant is seated. In other words, the greatest loads
applied by a seated occupant probably are exerted in the center of
the area in which the occupant is seated and the magnitude of the
forces imposed probably decreases in an essentially linear manner
away from this central area. Although, as indicated earlier, this
type of loading is symmetrical, it gives rise to fairly complex
shear and bending moment distributions through the frame of the
seat of a chair. An examination of the shear diagram which results
from a triangular distribution of forces suggests that an
essentially uniform distribution of loads along the frame of the
seat for the embodiments of both FIGS. 1 and 2 results.
If it is assumed, for instance, that each occupant of a chair
weighs 2P and that the chair illustrated in FIG. 1 can accommodate
one such occupant while the chair illustrated in FIG. 2 can
accommodate three such occupants, then each front and back portion
of the frame of the seat having a length L will receive a total
load of P in the case of the embodiment of FIG. 1 and 3P in the
case of the embodiment of FIG. 2. Across the entire length of the
front and back portions of the seat frame, the total load is 2P,
i.e., the weight of a single occupant. Similarly, across the entire
length of these members of the chair illustrated in FIG. 2 the
total load applied is 6P, i.e., the total weight of three occupants
each weighing 2P. In both embodiments, approximately one-half the
distributed load is probably exerted on the front portion of the
frame of the seat while the remaining load is exerted on the back
portion of the frame of the seat.
As a result of the loads applied as described in the preceding
paragraph, bending moments are developed in the front and back
portions of the frame of the seat in both embodiments. In both
embodiments, the maximum bending moment occurs at the midpoint of
the span of the front and back portions of the frame of the seat
between the legs 14. It will be understood that the bending moment
increases rather rapidly in the first one-third of the span and
then changes relatively little over the middle one-third of the
span. It can therefore be appreciated that the bending moment
developed in the front or back portion of the frame of the seat is
at or relatively near a maximum throughout the middle one-third of
the span.
The members forming the frame of the seat and subject to the
bending moments just described, including the front and rear
portions thereof, are preferably as slender as possible to minimize
the weight and cost of the chair.
The front portion of the frame of the seat is suitably provided
with a construction which enhances the flexural rigidity of the
frame. Preferably the frame is provided with a system of flexural
counters and associated spacers. A variety of different
arrangements of the counters and associated spacers could be used
but two preferred approaches are illustrated, one in FIG. 1 and the
other in FIG. 2.
Both of the embodiments of the invention illustrated in FIGS. 1 and
2 include a suitable countering means such as a tensile rod 32
operably associated with but vertically spaced below the front
portion 8 of the frame of the seat 6. This rod is referred to as a
tensile rod because, by virtue of the geometrical properties of the
structural section formed by the front portion 8 of the frame of
the seat and the tensile rod 32, the rod will only undergo tensile
stresses as the frame of the seat 6 undergoes flexure. The tensile
stresses developed in the tensile rod result in tensile forces
which assist in resisting flexure of the front portion 8 of the
frame of the seat 6. By considering the relation of the bending
moment discussed above to the front portion of the frame of the
seat, it can be appreciated that the tensile rod 32 extends along
the front portion of the frame of the seat directly below the point
at which the maximum moment is developed. In the embodiment
illustrated in FIG. 2, the tensile rod extends along slightly more
than the middle one-third of the span of the front portion 8 of the
frame of the seat 6.
The tensile rods 32 of both embodiments are rigidly connected to
the front portion of the frame of the seat by suitable first
spacing means such as primary spacing loops 34. The tensile rod 32
and the primary spacing loops 34 are preferably welded rigidly
together at each point of mutual contact shown. The primary spacing
loops 34 serve in whole or in part to maintain the tensile rod a
fixed vertical distance below the front portion 8 of the frame of
the seat 6. The magnitude of the vertical distance should be
sufficient to preclude the development of stresses in the tensile
rod greater than the yield stress of the particular material
composing the rod. Preferably, the primary spacing loops 34 are
integral with the tensile rod so that the tensile rod and the
primary spacing loops can be formed during manufacture from a
single length of material.
In the case of the embodiment illustrated in FIG. 2, secondary
spacing means or loops 36 which are not integral with the tensile
rod are employed to further ensure the proper positioning of the
tensile rod relative to the front portion of the frame of the seat.
In other words, in the embodiment illustrated in FIG. 2, primary
spacing loops 34 which are integral with the tensile rod 32 are
employed to maintain the tensile rod in position but additional,
secondary spacing loops 36 may also be employed between the primary
spacing loops to interconnect and maintain the relative positions
of the tensile rod and the front portion of the frame of the
seat.
The result of the two different arrangements of the tensile rod and
spacing loops described in the preceding paragraphs is that in the
embodiment illustrated in FIG. 1, the primary spacing loops 34
interconnect the tensile rod 32 and the front portion 8 of the
frame of the seat 6 to form a rigid, essentially triangular
lattice. The lattice is symmetrical about a generally vertical axis
of symmetry passing through the midpoint of the front portion of
the frame of the seat. This triangular configuration can be perhaps
best appreciated by examining the dashed lines appearing in FIG. 1.
The dashed lines represent the directions along which forces
developed in the spacing loops act in maintaining the position of
the tensile rod 32 during flexure. In contrast, in the embodiment
illustrated in FIG. 2, the primary and secondary spacing loops 34
and 36 interconnect the tensile rod 32 and the front portion 8 of
the frame of the seat 6 to form a rigid, essentially rectilinear
lattice. The lattice shown in FIG. 2 is also symmetrical about a
generally vertical axis of symmetry passing through the midpoint of
the front portion of the frame of the seat. The rectilinear
character of this lattice can be appreciated upon examination of
the dashed lines appearing in FIG. 2 which are used in the same
manner as the dashed lines of FIG. 1.
In protecting the back portion 12 of the frame of the seat 6 from
undue flexure, a somewhat different approach is taken.
As noted above, the frame of the back 18 includes upright members
connected to the back portion 12 of the frame of the seat 6 and
interconnected at the upper ends thereof by an elongated, top
member 20. In the case of the embodiment illustrated in FIG. 2,
intermediate upright members 24 are provided between the terminal
upright members 22. As will be better appreciated in the course of
subsequent discussion, these intermediate upright members 24
function as counters to at least partially suspend the back portion
12 of the frame of the seat 6.
As illustrated in FIGS. 1 and 2, each embodiment of the invention
employs a plurality of suitable suspending, countering means in the
form of hangers 42 to interconnect the upright members, the
elongated top member, and the back portion of the frame of the
seat. This is not to say that each hanger connects all three, but
rather, as is illustrated in either FIGURE, each hanger
interconnects at least two of the three structures mentioned, and
there is a sufficient plurality of hangers to interconnect all
three structures. The hangers 42 are preferably thin, elongated
strips each essentially rectangular in cross-section and
insufficiently rigid to sustain compressive loads of any
significance directed along the longitudinal axis thereof. The
hangers 42 serve to suspend the back portion 12 of the frame of the
seat 6 from the upright members and the elongated top member. The
hangers thus transfer at least a portion of the loads exerted on
the back portion of the frame of the seat into those of the legs
connected to that portion of the frame of the seat. The suspension
of the back portion of the frame of the seat serves to reduce the
bending moments that develop therein by providing support for the
back portion of the frame of the seat from above.
In order to optimize the effectiveness of the suspension of the
back portion of the frame of the seat, the hangers 42 are arranged
to form a triangular lattice with the upright members, elongated
top members, and the back portion of the frame of the seat. The
triangular lattice formed thereby is symmetrical about an axis
passing through the midpoint of the frame of the back of the chair.
This symmetrical, triangular form requires a minimal number of
hangers and also provides some reinforcement against skewing of the
frame from the rectangular configurations illustrated.
In the case of the embodiment illustrated in FIG. 2, it should be
noted that the intermediate upright members 24 are two in number
and are mutually interconnected by a portion of the triangular
lattice described in the preceding paragraph to form a median panel
44. The median panel 44 and thus the middle portion of the frame of
the seat is suspended as a unit by several hangers. These hangers
extend diagonally from each of the terminal upright members 22 and
the elongated top member 20 to one of the intermediate upright
members 24 and the back portion of the frame of the seat 6. Such an
arrangement is useful in suspending the middle portion of the back
portion 12 of the frame of the seat 6 undergoing bending moments of
the greatest magnitude.
As should be readily apparent from FIGS. 1 and 2 a plurality of
legs is connected to the frame of the seat 6 and each leg extends
downwardly from a corner thereof to support the frame of the seat.
As indicated earlier, each leg 14 is connected to the frame of the
seat through a suitable gusseting means such as the gusset 16. As
perhaps best illustrated in FIG. 5, each gusset is connected to the
frame of the seat in such a manner that it supportingly braces and
grips, about at least upper and lower portions, one or more members
forming the frame of the seat. The gusset in this way rigidly
connects a leg to the frame of the seat.
As perhaps best illustrated in FIGS. 4 and 7, each gusset 16
preferably forms a right angle and extends around a corner formed
by the intersection of the members forming front or back portions 8
or 12 and members forming side portions 10 of the frame of the
seat. As can be seen from FIG. 4 each gusset is thus symmetrically
arranged around a corner and therefore supportingly embraces and
grips equal segments of the intersecting members.
Each gusset supportingly embraces and grips members forming the
frame of the seat through top and bottom flanges interconnected by
a planar portion. As best illustrated in FIGS. 5 and 7, each gusset
includes at least one top flange 46 which covers a segment 48 of
the horizontal leg of one or more members forming the frame of the
seat. Each gusset also includes at least one bottom flange 50
having a horizontal segment 52 extending inwardly beneath a segment
54 of the lowermost edge of the vertical leg of the right angle
formed by members forming the frame of the seat. These two flanges,
that is, the top flange 46 and the bottom flange 50 are
interconnected by a planar portion 56 which covers a segment 58 of
a vertical leg of the right angle formed by members forming the
frame of the seat.
Suitable fasteners 60 extend through the planar portion 56 and
through the vertical leg of the member forming the frame of the
seat to connect the gusset to the frame of the seat as illustrated
in FIGS. 5 and 7. Once these fasteners are tightened as illustrated
in FIG. 5, the top and bottom flanges and the planar portion
therebetween supportingly embrace and grip one or more members
forming the frame of the seat. In this way, a solid connection is
formed between the leg and the chair and the stability of the
members forming the frame of the seat is considerably enhanced. As
will be more clearly appreciated from subsequent discussion, this
feature is also important in two further aspects, viz., in reducing
the unsupported span of the members forming the frame of the seat
and in ensuring a solid structural interface between the frames of
the seat and the back 6 and 18, respectively.
With respect to reducing the unsupported span of the members
forming the frame of the seat, it can be appreciated from an
examination of FIG. 5 that each gusset 16 preferably includes two
mutually orthogonal limbs 62 each of which carry top and bottom
flanges 46 and 50 and an interconnecting planar portion 56. The
limbs 62 extend toward the midpoints of the members intersecting to
form the frame of the seat and thus serve to reduce the unsupported
span of these members. FIGS. 3 and 4 clearly illustrate this
feature.
The fasteners 60 mentioned earlier each penetrate a limb 62 of a
gusset and one of the members intersecting to form the frame of the
seat to secure the gusset to the frame of the seat. The resulting
reduction of the unsupported span of the members forming the frame
of the seat is important because the bending moments developed
therein are a function of the unsupported span. Any reduction in
the unsupported span of a member serves to reduce the bending
moment developed therein so long as the loading of the member
remains unchanged.
Preferably the legs 14 employed to support the frame of the chair
are generally rectangular in cross-section although any other
cross-sectional configuration can be used. Optimally, each leg
supporting a corner of the frame of the seat has at least one
orthogonal corner 64 which is matingly receivable in the interior
66 of the generally right angle formed by each gusset. The most
preferable configuration is illustrated in FIG. 7 in which the
orthogonal surfaces of the leg forming the orthogonal corner 64
seat against the surfaces of the gusset which intersect to form the
right angle thereof. During manufacturing of the gusset, the
orthogonal corner 64 of each leg 14 can be inserted into the
interior angle of the gusset and in this way the leg can be quickly
and accurately oriented for securement in place.
The securement of the leg to the gusset is further enhanced by
vertical portions of the bottom flanges 50. As illustrated in FIG.
7 each bottom flange 50 extends arcuately downwardly from the
horizontal segment 52 thereof to form a vertical segment 68. The
vertical segments of the two bottom flanges 50 at least partially
enclose and grip the leg to which the gusset is connected. Thus,
with the leg seated inside the gusset and at least partially
enclosed by the vertical segments 68 of the bottom flanges 50, the
leg can be permanently and accurately connected to the gusset by
welding or otherwise.
Optimally these legs are splayed to broaden the base and thereby
enhance the stability of the chair. Most desirably the base of the
chair is broadened in both directions, i.e., both forwardly or
reawardly and laterally. This arrangement is most effectively
accomplished by bending each leg about diagonal axes to thus
diagonally splay the leg relative to its associated gusset and the
frame of the seat. A diagonal axis is an axis passing through the
corners of the rectangular leg across a corner of the frame of the
seat. Representative diagonal axes about which a leg may be bent
are represented by the dashed lines S--S shown in FIGS. 4 and
7.
To provide symmetry and optimal stability, each leg is bent about
axes passing through the same two corners at points near the lower
portion of the gusset and again near the lower end of the leg. The
bending near the lower end of the leg provides vertical contact
between the floor or other surface and the leg of the chair.
The embodiments illustrated in FIGS. 1 and 2 each include a pair of
rigid arms 26 which each extend generally upwardly from connection
with a side portion 10 of the frame of the seat to connection with
a terminal upright member 22 at a point intermediate the ends
thereof. The interconnection of each arm between the two frames
serves to reinforce the terminal upright members 22 in such a way
as to assist in the resistance of flexural loads.
Preferably, though not necessarily, the rigid arms 26 are formed of
a tubular material. The tubular quality of the arm affords a
significant advantage in effecting the connection between each arm
and the frames 6 and 18. It can readily be appreciated from an
examination of FIGS. 1-4 that each arm is flattened to relatively
thin, planar portions 38 at points of connection with each frame.
This flattening permits the effective use of a fastener such as the
threaded fastener 40 illustrated or a rivet which passes through
the relatively thin planar portions to connect the arm 26 to one of
the two frames.
As previously indicated, the frames forming the seat and back of
the chair are preferably rectangular and interconnected. Resistance
to loads applied to the frame of the back 18 is provided by the
terminal upright members 22, the intermediate upright members 24
serving principally as counters to suspend the back portion 12 of
the frame of the seat. Intermediate upright members can be
connected to the back portion of the frame of the seat in any
desired manner, for instance by simple threaded fasteners. The
connection between the terminal upright members and the frame of
the seat, however, must be sufficiently durable to sustain the
portion of the loading exerted on the frame of the back and not
restrained by the rigid arms 26.
The problem of providing an adequate structural interface between
the frames of the seat and the back 6 and 18, respectively, is
exacerbated by the fact that the frame of the back is commonly
inclined relative to the frame of the seat and little space is
available for any reinforcement.
The metal chairs of the present invention include a unique
telescoping joint which is structurally interrelated with the
gusseted connection of the rear legs of the chair to the frame of
the seat and which provides significant structural support
therefor. As illustrated in FIG. 7 a slot 70, preferably U-shaped,
is formed in the top flange 46 of each gusset supporting the
intersection of members forming the back and side portions of the
frame of the seat. The slot 70 extends diagonally into the right
angle formed by the gusset. A solid cylindrical pin 72 is rigily
connected to the interior 74 of each intersection of the vertical
legs of the members forming the side and back portions of the frame
of the seat as illustrated in FIGS. 4, 5, and 7. The cylindrical
pin 72 extends upwardly through the slot 70 of each gusset
connected to a rear corner of the frame of the seat.
Each terminal upright member 22 has a lower portion 76 which can be
telescoped over one of the cylindrical pins 72 to connect the
frames of the back and the seat. As illustrated in FIG. 6 the lower
portion 76 of each terminal upright member 22 is preferably
reconfigured during manufacture into a generally tubular portion
capable of sliding snugly over one of the cylindrical pins 72.
This particular arrangement with a solid cylindrical pin extending
from the frame of the seat avoids the enlargement of the joint
which would be required if the female portion of the joint extended
upwardly from the frame of the seat and the male portion depended
from the frame of the back. This arrangement also stabilizes the
gussets, rear legs and seat frame at the point of their
intersection.
SUMMARY OF MAJOR ADVANTAGES
It will be appreciated that in providing a metal chair according to
the present invention certain significant advantages are
obtained.
Of particular importance is the advantage that the frame of the
seat of the chair is made sufficiently flexurally rigid that loads
applied thereto can be sustained without adding significant amounts
of materials or employing much additional labor.
It is another advantage that the chair legs can be splayed in two
directions to form a stable base and yet are securely connected to
the frame of the chair in a manner such that bending moments and
shear forces introduced into the connection can be readily
sustained. Also, each leg is connected to the chair in such a way
that the leg can be quickly and accurately oriented relative to the
frame of the chair during fabrication thereof.
Still another significant advantage of the invention resides in the
fact that the structural interface between the frames forming the
seat and back of the chair is quite simple and yet structurally
capable of sustaining loads normally imposed on the frame of the
back.
The metal chair of the present invention is quite sturdy, light in
weight, and compact. The chair can be disassembled and the
components packaged or stored in a relatively small, flat area and
readily assembled by a person who is mechanically unskilled.
In describing the invention, reference has bee made to a preferred
embodiment. However, those skilled in the art and familiar with the
disclosure of the invention may recognize additions, deletions,
substitutions, or other modifications which would fall within the
purview of the invention as defined in the claims.
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