U.S. patent number 3,751,789 [Application Number 05/289,427] was granted by the patent office on 1973-08-14 for method for hinging a foldable tablet arm to a stackable chair.
This patent grant is currently assigned to The Vecta Group, Inc.. Invention is credited to Roy W. Fink.
United States Patent |
3,751,789 |
Fink |
August 14, 1973 |
METHOD FOR HINGING A FOLDABLE TABLET ARM TO A STACKABLE CHAIR
Abstract
A Method For Applying Torque To Support Members For A Foldable
Tablet Mounted On An Arm Of A Stackable Chair.
Inventors: |
Fink; Roy W. (Portage, MI) |
Assignee: |
The Vecta Group, Inc.
(Kalamazoo, MI)
|
Family
ID: |
26805972 |
Appl.
No.: |
05/289,427 |
Filed: |
September 15, 1972 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
108511 |
Jan 21, 1971 |
3712668 |
|
|
|
Current U.S.
Class: |
29/434; 29/446;
297/239; 16/374; 297/162 |
Current CPC
Class: |
A47C
3/04 (20130101); A47C 7/70 (20130101); Y10T
29/4984 (20150115); Y10T 16/551 (20150115); Y10T
29/49863 (20150115) |
Current International
Class: |
A47C
3/04 (20060101); A47C 7/70 (20060101); A47C
7/62 (20060101); A47C 3/00 (20060101); B23p
011/00 (); B23p 011/02 (); A47b 039/00 () |
Field of
Search: |
;297/417,239,161,160,162,248 ;16/128A,140,141,142,160,161,162
;312/313 ;248/293,291,284 ;211/150 ;29/234,246 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gilliam; Paul R.
Parent Case Text
This is a division, of application Ser. No. 108 511 , filed Jan.
21, 1971 now U.S. Pat. No. 3,712,668
Claims
What is claimed is:
1. A method for applying a predetermined amount of frictional
resistance to the pivotal movement of a tablet arm rest pivotally
mounted by hinge means upon a pair of spaced and substantially
upright support elements, comprising the steps of:
applying a torque to at least one of said elements;
attaching both of said elements by means of their hinge means to
said arm rest while maintaining the application of said torque,
whereby the restoring force in said one element applies a stress
upon the hinge means attached thereto so that said hinge means
resists pivotal movement of the arm rest.
2. A method according to claim 1 wherein a torque is applied to the
other element before attachment thereof by its said hinge means to
said arm rest.
Description
FIELD OF THE INVENTION
This invention relates in general to a nestable and gangable tablet
arm chair and, more particularly, to a type thereof having a hinged
tablet arm which is movable from a substantially horizontal
operational position into a downwardly and outwardly sloping
storage position which permits stacking of said chair with another
similar chair.
BACKGROUND OF THE INVENTION
Persons familiar with the use and manufacture of gangable and
stackable chairs, and especially chairs used in schools,
auditoriums and the like, where it is desirable to have a tablet
arm, are aware that much work and effort have been directed to the
development of a completely acceptable chair capable of meeting
these requirements. However, chairs produced for this purpose to
date have not fulfilled the need due to one or more reasons. That
is, either the chair could not be both stacked and ganged if it had
a foldable tablet or, if stackable and gangable, the tablet
remained in an awkward position when in its storage or stacking
position. Moreover, it was found that stackable tablet arm chairs
having movable tablet arms had sacrificed strength to the extent
that they could not be used without risk of early break-down in
situations where reasonable, but rough, treatment could be
expected.
For example, most of the previous stackable chairs for general
purpose use have had metal legs which have often been tubular.
Where a tablet arm was included, the arm supported bracket was
either welded or bolted to other parts of the chair, such as the
legs. Use of bolts necessitates openings which obviously weaken
both parts at the point of connection. However, the typical weld is
no better. That is, the welding creates an annealed zone with a
reduced yield strength, an abrupt and material change in
cross-sectional area which concentrates stress, and a stiffened
section which effectively resists distribution of a bending moment
beyond the change in cross-sectional area. Thus, it comes as no
surprise that failures under stress are most likely to occur at, or
even be induced by, a typical weld between the legs and arm support
bracket.
Accordingly, a primary object of this invention is the provision of
a stackable and gangable chair having a tablet arm capable of
hinged movement between an operative position and a storage
position, said storage position being such that obstruction to
stacking and storage is minimized.
A further object of this invention is the provision of a stackable
chair which has a hinged tablet arm capable of withstanding abusive
use, which is easy to maintain and is relatively simple in
construction.
A further object of this invention is the provision of a device for
connecting a metallic tablet arm support to metallic legs of a
chair whereby the annealing effects of welding are minimized, an
abrupt and material change in cross-sectional area is avoided and a
substantially stiff section is eliminated.
Other objects and purposes of this invention will become apparent
to persons familiar with chair structures of this type upon reading
the following descriptive material and examining the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a chair embodying the invention,
same being illustrated in the operative or use position.
FIG. 2 is a perspective view of said chair in the storage or
stacking position.
FIG. 3 is a front view of a pair of said chairs ganged together,
one in the storage position and one in the operative position.
FIG. 4 is a sectional view taken along line IV--IV in FIG. 3.
FIG. 5 is a fragmentary sectional view taken along the line V--V in
FIG. 3.
FIG. 6 is a sectional view taken along the line VI--VI in FIG.
3.
FIG. 7 is a sectional view taken along the line VII--VII in FIG.
6.
FIG. 8 is a sectional view taken along the line VIII--VIII in FIG.
2.
FIG. 9 is a broken fragment of FIG. 6.
FIG. 10 is a front elevational view of the pair of chairs in the
stacked position.
FIG. 11 is a sectional view taken along the line XI--XI in FIG.
10.
FIG. 12 is a sectional view substantially as taken along the line
XII--XII in FIG. 8.
For convenience in description, the terms "upper," "lower,"
"front," "rear" and words of similar import will have reference to
the chair embodying the invention as appearing in FIG. 3 which
illustrates front views of the chair.
The words "right" and "left" will have reference to those sides of
said chair adjacent the right and left sides, respectively, of a
person occupying said chair in a normal manner.
SUMMARY OF THE INVENTION
The objects and purposes of the invention, including those set
forth above, have been met by providing a stackable and gangable
chair having a folding tablet arm movable between a substantially
horizontal operative position and a downwardly and outwardly
sloping storage or stacking position. The tablet arm is hingedly
mounted upon the upper end of a tablet support member, which in
turn is rigidly secured to the legs of the chair. The tablet
support member has upwardly diverging arms, and the front chair
legs diverge downwardly with respect to the rear chair legs to
permit stacking. Mating ganging members are mounted upon the legs
on the opposite sides of the chair, which ganging members are
disposed outwardly of the chair seat whereby stacking is
accomplished when the tablet arms are in their storage
positions.
DETAILED DESCRIPTION
FIGS. 1 and 2 illustrate a chair 10 constructed according to the
present invention. The chair 10 includes a back 11 and a seat 12
which, in a preferred embodiment of the invention, are constructed
in one piece. The chair 10 includes right front and rear legs 13
and 14 and additionally includes left front and rear legs 16 and
17. The pair of right legs 13 and 14 diverge downwardly away from
the seat, as do the left legs 16 and 17, in order to permit
stacking of two such chairs 10. The pair of legs 13 and 14 define a
substantially vertical plane and they are disposed slightly
outwardly of the right edge of the seat 12. The pair of legs 16 and
17 define a substantially vertical plane and they are disposed
slightly outwardly of the left edge of the seat. The front legs 13
and 16 preferably define a plane which slopes downwardly and
forwardly relative to the seat 12, and the rear legs 14 and 17
preferably define a plane which slopes downwardly and rearwardly
relative to the seat.
The front legs 13 and 16 are rigidly connected, here integrally, to
a center support portion 18 which extends primarily in the
horizontal direction and which is disposed adjacent to and under
the chair seat 12. The rear legs 14 and 17 are also rigidly, here
integrally, connected by a center support portion 19 which is
disposed adjacent to and under the seat, but rearwardly of the
front center support portion 18. Suitable mounting means 21 is
rigidly secured to and extends between the center support portions
18 and 19, and said mounting means 21 is rigidly connected to the
chair seat 12.
The chair construction described above may be substantially
conventional. Further, the downwardly diverging front and rear legs
of the chair may be formed with their respective center support
portions from two pieces of tubing so that they appear as a pair of
U-shaped members before connection to the mounting means 21.
The chair 10 is provided with a substantially V-shaped tablet arm
support 22 which is secured to the legs 13 and 14 and opens
upwardly. A tablet arm 23 is mounted upon the upper free ends of
the front and rear support elements 28 and 29, respectively, of
said tablet arm support 22. The tablet arm 23 is adapted to be
normally disposed in a substantially horizontal position of use, as
illustrated in FIG. 1. The tablet arm includes an enlarged front
portion 26 adapted to support an article or writing materials, for
example. An elongated arm rest 27 is connected to and extends
rearwardly from the front portion 26.
The V-shaped tablet arm support 22 (FIG. 3) is disposed
substantially within a vertical plane which is parallel with and
outwardly of the vertical plane defined by the right pair of legs
13 and 14. The front and rear support elements 28 and 29,
respectively, (FIG. 6) diverge upwardly and they and inclined
forwardly and rearwardly, respectively, to the vertical. The lower
ends of the elements 28 and 29 are rigidly, here integrally,
connected by a central portion 31, which extends substantially
horizontally and is disposed at an elevation approximately mid-way
between the upper and lower ends of the chair legs.
The arm support 22 (FIG. 6) is rigidly connected to the legs 13 and
14 by means of weld brackets 32 and 32A. Particularly, a first
X-shaped weld bracket 32 (FIGS. 6, 7 and 9) is disposed adjacent
the point of intersection of and between the front support elements
28 and the front legs 13. The bracket 32 includes a first crossbar
33 which is disposed adjacent to and extends along the front
support element 28. Said crossbar 33 has a concave outer surface,
transversely thereof, which snugly embraces the cylindrical support
element 28, but other cooperating surfaces could be provided. Said
crossbar 33 is connected near its opposite ends to the leg 13 by
welds 34.
The bracket 32 includes another elongated crossbar 35 which is
adjacent to and extends along front leg 13. The crossbar 35 is
similar to crossbar 33 and is secured near the opposite ends
thereof to the element 28 by welds 34.
An X-shaped bracket 32A (preferably a mirror image of bracket 32)
is provided at the intersection of and between the rear leg 14 and
the rear support element 29 for fixedly interconnecting same. The
angle of intersection between the support elements 28 and 29 and
the respective chair legs 13 and 14 are preferably identical so
that the brackets 32 and 32A can be mirror images of each other.
The crossbars 33, 35 and 33A, 35A of the X-shaped brackets are
preferably integral so that they provide a strong and durable but
flexible connector which can be easily fabricated and formed from
sheet metal.
The upper ends of the support elements 28 and 29 are connected to
and support hinge assemblies 36 and 37, which pivotally connect the
table arm 23 to the V-shaped arm support 22. The hinge axis of the
assemblies 36 and 37 are substantially disposed within the same
horizontal plane and are coaxial. The assemblies 36 and 37 are
preferably substantially identical to each other so that only the
hinge assembly 36 need be described in detail.
The front hinge assembly 36 (FIGS. 2 and 8) includes a stationary
hinge plate 38 rigidly secured, as by welding, to the upper end of
the front support element 28. The hinge plate 38 is normally
substantially horizontal and includes a flange 39 (FIG. 4)
extending downwardly along approximately three edges thereof. The
downwardly extending flange not only hides the weld seams between
the element 28 and plate 38, but also imparts additional strength
and rigidity to the hinge plate 38 and minimizes sharp edges or
corners where they could be injurious. The hinge plate 38 is also
provided with a conventional hinge knuckle 41 integral with an edge
thereof.
The hinge assembly 36 includes a movable hinge plate 42 fixedly
secured to the underside of the table arm 23 in a conventional
manner, such as by means of screws 43, along the straight inner
edge 48 thereof. The hinge plate 42 includes a pair of spaced and
conventional hinge knuckles 44 integrally connected to the outer
edge thereof. The hinge knuckles 44 are adapted to be axially
aligned with and disposed on opposite axial ends of the hinge
knuckle 41, so that a hinge pin 46 can be inserted through the
aligne knuckles in a conventional manner for hingedly connecting
the hinge plates 38 and 42.
The hinge assembly 36 is also provided with an elongated stop or
abutment 47 fixedly secured to, and projecting downwardly from, the
underside of the stationary hinge plate 38. The stop 47, which in
the illustrated embodiment comprises a short rod welded to the
hinge plate, is parallel with and laterally spaced inwardly from
the hinge pin 46. the stop 47 is positioned for engagement by the
longitudinal edge 48 of the tablet arm 23 to arrest the pivotal
movement thereof when it reaches the storage position substantially
as illustrated in FIGS. 8 and 10. The stop 47 thus prevents the
tablet arm from moving into suspended, substantially vertical
position, but instead maintains the tablet arm in an inclined
stacking or storage position wherein the tablet extends both
downwardly and outwardly from the hinge axis thereof.
The hinge assembly 37 (FIGS. 2 and 4) has a fixed plate 38A with an
integral knuckle 41A and a movable plate 42A with spaced integral
knuckles 44A. A stop 47A is secured to the lower surface of plate
38 which has an integral flange 39A.
The chair 10 is also preferably provided with ganging means for
interlocking a plurality of said chairs in side-by-side
relationship and in a row. The ganging means includes male and
female ganging members, one being fixedly secured to one side of
the chair and the other being secured to the opposite side thereof.
In the illustrated embodiment, the male ganging member 51 (FIG. 1)
is disposed near the right pair of legs 13 and 14, and it is
rigidly connected, as by welding, to the V-shaped tablet arm
support 22 near the lower end thereof. The male member 51 is
fabricated from metallic rod-like material arranged to form a
horizontal elongated rectangle. Portions 50 of the member 51 are
offset inwardly at the points of engagement between the member 51
and the elements 28 and 29 of the tablet arm support 22. This
provision spaces the remainder of the member 51 away from the
tablet arm support so that the female ganging member 52 can move
downwardly past the elements 28 and 29 during a stacking operation.
The opposite substantially rectangular end portions 53 and 54 of
the member 51 extend frontwardly and rearwardly beyond the legs 13
and 14, respectively.
The female ganging member 52 (FIGS. 5 and 6) is fixedly connected
to the left pair of legs 16 and 17. The female member 52 is also
fabricated from metallic rod-like material arranged in a
horizontally elongated loop, said member 52 has opposite end
portions 56 and 57 which extend frontwardly and rearwardly beyond
the respective legs 16 and 17.
The end portions 56 and 57 on the female ganging member 52 are both
bent outwardly and are substantially perpendicular to the central
portion of the member 52. These portions 56 and 57 converge
upwardly so that they can overlap the upper corners of the planar
end portions 53 and 54 of a male ganging member mounted upon a
similar, adjacent chair, whereby the to chairs are releasably held
in side-by-side relationship.
The exact structural details of the ganging members 51 and 52, and
the manner in which they coact, are explained in greater detail in
copending application Ser. No. 79,732, filed Oct. 12, 1970, and
entitled "IMPROVED GANGING AND STACKING CHAIR," which application
is assigned to the Assignee of this application.
While the ganging members 51 and 52 may be secured to the legs 13,
14 and 16, 17, respectively, in any convenient manner, projection
welding is preferred, because it minimizes the heat required and/or
generated to effect the weld.
As shown in FIG. 12, the hinge axes 61 and 62 of the hinge
assemblies 36 and 37, respectively, are preferably at slight angles
to the pivotal axis 63 of the arm 23 before said assemblies are
attached to the arm. The amount of the angles may be relatively
small, such as about 3 degrees. Thus, just before the hinge plates
42 and 42A are secured to the arm 23, the support elements 28 and
29 are twisted around their length-wise axes (28 counterclockwise
and 29 clockwise) until the axis 61 and 62 are coincident with the
axis 63. As a result, the torque applied to the elements 28 and 29
will react to prestress the hinge assemblies 36 and 37 whereby
friction opposing pivotal movement of the arm 23 is increased to
the point that the arm 23 will tend to remain in any position where
it is placed between and including those shown in FIGS. 1 and 2.
This arrangement improves the safety of the chair in that it avoids
the accidental falling of the arm from a vertical, upright
position, as shown in 23C in FIG. 3, into either of the positions
at 23 and 23A.
OPERATION
The normal position of use for the chair 10, built according to the
present invention, is illustrated in FIG. 1, wherein the tablet arm
is horizontally disposed above one edge portion of, and extending
partially over, the seat so that the table arm is usable as a
support surface. Further, if desired, a plurality of identical
chairs, such as the identical chairs 10 and 10A illustrated in FIG.
3, can be ganged in side-by-side relationship to form a row of
interconnected chairs. Particularly, the male ganging member 51
provided on the chair 10 is engaged by the female ganging member
52A provided on the chair 10A for interconnecting the chairs. The
engagement of these ganging members is accomplished (FIGS. 6 and 7)
by raising the chair 10A so that the female ganging member 52A is
disposed directly above the male ganging member 51, after which
chair 10A is lowered so that planar end portions of the male
ganging member 51 extend into the sloped end portions formed on the
female ganging member 52A. This interlocked relationship of the
ganging members is accomplished when both chairs are resting on the
same planar surface.
Further, with the chairs in the ganged relationship illustrated in
FIG. 3, each tablet arm 23 can be individually swung around its
hinge axis from its use position of FIG. 1 into its storage
position of FIG. 2 to facilitate movement of a person into or out
of the chair.
When it is desired to stack the chairs one upon another, the tablet
arm 23 of each chair is first moved into the storage position
illustrated in FIG. 2, wherein the tablet arm extends downwardly
and outwardly from its hinge axis. The hinged movement of the
tablet arm is limited by engagement between the hinge stop 47 and
the longitudinal edge 48 of the tablet arm.
With the tablet arms in the storage position, the chairs can be
stacked one on top of another substantially as illustrated in FIGS.
10 and 11. The downward divergence of the front and rear legs,
whereby the legs of an upper chair are disposed above and ride on
the legs of a lower chair, prevents said legs from interfering with
the vertical stacking. The laterally offset location and the
V-shaped configuration of the tablet arm supports 22 prevents their
interference with the stacking operation. The storage position of
the tablet arms is such that they are disposed one above another in
the stacked positions, as illustrated in FIG. 10. The vertical
nesting of the V-shaped tablet supports is made possible by the
fact that the hinge pin 46 is laterally and outwardly offset from
the support elements 28 and 29. Thus, when the tablet arm 23 is in
the storage position the tablet support 22B of the chair 10B,
directly above chair 10, can pass vertically downwardly between the
pair of stationary hinge plates 38 and 38A on the lower chair
10.
When the chairs are in the stacked position, the weight of an upper
chair is preferably transferred to the next lower chair due to
bearing engagement between the legs of the two stacked chairs.
However, the tablet arm support 22 may also be engaged by the
support 22B when the chairs are in stacked positions.
While the chairs illustrated in the drawings are all provided with
a pivotally movable tablet arm mounted on the side of the chair
suitable for right-handed persons, it will be readily apparent that
the present invention is also adaptable for so-called left-handed
chairs, that is, chairs having the swingable tablet mounted on the
opposite side of the chair.
The bracket 32 (FIGS. 7 and 9) is constructed, and the bars 33 and
35 thereof are attached to the element 28 and leg 13, respectively,
so that adverse effects from welds under stress at least minimized.
That is, for example, the bar 33 is welded to the element 28 at two
points substantially spaced, such as three or four inches, and each
weld can be relatively small, by comparison with a conventional
weld which would be required directly between the leg 13 and
element 28, if the bracket 32 were not used. The small welds are
completely adequate because both the bar 33 and the portion of the
element 28 between welds can flex under stress, and this greatly
reduces the likelihood of a break at the weld when a stress is
applied to the element 28 or leg 13.
Since the welds are small and produced by a fast acting electrical
process, annealing is minimized and restricted to the immediate
location of the weld. Thus, there is no extensive, heat affected
zone which has a lower yield strength and, hence, a lower
resistance to failure under stress.
The bracket 32 obviously strengthens the adjacent portions of the
leg 13 and element 28, but it does not create stress concentrations
due to abrupt, large changes in cross-sectional area. A stress
applied to the leg 13, for example, is distributed along almost the
full length of the bar 35 in a manner very nearly corresponding to
such distribution if the leg was unattached to the bracket 32 or
the element 28.
The brackets 32 and 32A also serve as accurate spacers between the
legs and arm support 22 to facilitate stacking or nesting of plural
chairs 10.
The method of pre-stressing the hinges 36 and 37 (FIG. 12) is
accomplished by applying a torque or torsional deflection to the
elements 28 and 29 prior to attachment of their hinges to the arm
rest 23. The restoring forces within the elements 28 and 29 impose
a distortion upon their hinges whereby frictional resistance to the
movement of the arm rest can be substantially increased in a
predetermined manner.
Although a particular preferred embodiment of the invention has
been disclosed in detail for illustrative purposes, it will be
recognized that variations or modifications of the disclosed
apparatus, including the rearrangement of parts, lie within the
scope of the present invention.
* * * * *