US3751789A - Method for hinging a foldable tablet arm to a stackable chair - Google Patents

Abstract

A Method For Applying Torque To Support Members For A Foldable Tablet Mounted On An Arm Of A Stackable Chair.

Description

Fink Aug. 14, 1973 METHOD FOR HINGING A FOLDABLE 211/150; 29/234. 246

TABLET ARM TO A STACKABLE CHAIR 75 Inventor: Roy w. Fink, Portage, Mich. 1 References Cited [73] Assignee: The Vecta Group, Inc., Kalamazoo, UNITED STATES PATENTS Mich r 2,646,106 7/1953 Terry 16/140 3,156,498 11/1964 BlOdee 297/162 [22] F1166: Sept. 15, 1972 3,174,795 3/1965 Chapman 6: a1 297/160 3,362,669 l/1968 Legge 248/293 [21] APPL 289,427 3,467,432 9/1969 Sullivan 297/162 Related US. Application Data [62] Division of Ser. No. 108,511, Jan. 21, 1971, Pat. NO. Examiner-Paul Gilliam 3,712,668. Attorney--Raymond H. Blanchard [52] US. Cl 29/434, 29/446, 16/140, 57 01 A Method For Applying Torque To Support Members [51] Int. Cl.. B23p 11/00, 323p 11/02, A47b 39/00 52 Field 61 Search 297/417, 239, 161, A mdable Tablet Mwmed of A Stackable Chair.

2 Claims, 12 Drawing Figures PAIENIEU Am: 1 4mm sum 2 0; 3

METHOD FOR IIINGING A FOLDABLE TABLET ARM TO A STACKABLE CHAIR This is a division, of application Ser. No. 108 511 filed Jan. 21, 1971 now U.S. Pat. No. 3,7l2,668

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 po sition 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. I 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-Vl in FIG. 3.

FIG. 7 is a sectional view taken along the line Vll- --VII in FIG. 6.

FIG. 3 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. II is a sectional view taken along the line XI-XI in FIG. 10.

FIG. I2 is a sectional view substantially as taken along the line XIIXII 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 memher, which in turn is rigidly secured to the legs of the chair. The tablet supportmember 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 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 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 36and 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 comers 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 I is also preferably provided with ganging means for interlocking a plurality of said chairs in sideby-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 M, 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 fonn a horizontal elongated rectangle. Portions 50 of the member 51 are offset inwardly at the points of engagement between the member SI 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. and 6) is fixedly connected to the left pair of legs 16 and 17. The female member 52 is also fabricated from metallic rodlike 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 comers 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 IM- PROVED GANGING AND STACKING CHAIR," which application is assigned to the Assignee of this application. I

' While the ganging membersSl and 52 may be secured to the legs 13, 14 and l6, 17, respectively, in any convenient manner, projection welding is preferred, becauseit-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 am. 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 am 23 will tend to remain in any position where it is placed between and including those shown in FIGS. I 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. ll, 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 l0 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 I0 is engaged by the female ganging member 52A provided on the chair MIA 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 SI, after which chair 10A is lowered sothat 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 tabletarm 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 43 of the tablet amt.

With the tablet arms in the storage position, the chairs can be stacked one on top of another substantially as illustrated in FIGS. l0 and Ill. 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. llll. 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 2% and 29. Thus, when the tablet arm 23 is in the storage position the tablet support 223 of the chair WB, directly above chair 110, can pass vertically downwardly between the pair of stationary hinge plates 33 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 228 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 lefthanded 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.

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.

Claims (2)

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.

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