US3845986A - Stackable seating units - Google Patents

Stackable seating units Download PDF

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US3845986A
US3845986A US39526673A US3845986A US 3845986 A US3845986 A US 3845986A US 39526673 A US39526673 A US 39526673A US 3845986 A US3845986 A US 3845986A
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wires
seat
chair
assembly
arc
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D Rowland
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    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47C—CHAIRS; SOFAS; BEDS
    • A47C7/00—Parts, details, or accessories of chairs or stools
    • A47C7/02—Seat parts
    • A47C7/28—Seat parts with tensioned springs, e.g. of flat type
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47C—CHAIRS; SOFAS; BEDS
    • A47C3/00—Chairs characterised by structural features; Chairs or stools with rotatable or vertically-adjustable seats
    • A47C3/04—Stackable chairs; Nesting chairs
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47C—CHAIRS; SOFAS; BEDS
    • A47C5/00—Chairs of special materials
    • A47C5/04—Metal chairs, e.g. tubular
    • A47C5/06—Special adaptation of seat upholstery or fabric for attachment to tubular chairs

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  • ABSTRACT Inventor: David L. Rowland, 8 E. 62nd St., A compactly stacking chair with a spring-resilient seat. New York, N.Y. 10021 The chair has a frame constructed to enable compact [22] Filed: Sept. 7, 1973 itlacking.
  • the non-resilient stacking chairs may be compactly stackable, with seats and backs thinner than the frame, but they lack the comfort-giving feature of spring resilience.
  • a hard seat can, at best, only approximate a comfortable shape, since human posteriors vary greatly. While seats theoretically might be tailor-made for each individual, this would be costly and would require carrying seats to wherever they would be used. A seat which automatically tends to shape itself to each users posterior is a better solution to the problem. A seat with proper resilience in the right places is thus an object of this invention.
  • An ideal seat therefore, has:
  • An object of this invention is to provide a seat for stacking chairs more nearly approaching the ideal than has been achieved in the past.
  • the seat and back structure may be considered as an improvement over my earlier U.S. Pat. No. 2,803,293.
  • each of the sinuous springs had a hook on each end which partially encircled a rigid frame member. This hooking did not positively prevent movement of the wires relative to the frame, nor did it hold them in proper position relative to each other prior to their being coated with plastic. Partly because there was only line contact at best between the wire and the frame (and unless the chair frame size was exactly matched with the size of the hook, there would be contact at only two points), the hook tended to rotate when subjected to force, as when someone sat on the chair.
  • the seat is too stiff and lacks the proper two-way stretch quality desired.
  • Proper choice of durometer according to the principles of this invention enables the plastic to serve as a shock absorber and provides a snubbing action against bounce.
  • bounce-dampening can be achieved in this invention by employing in the assembly some wires that differ from the other wires in gauge, shape, or spring tension or temper, so that their harmonic vibration periods are different.
  • the amount of the seating area occupied by the metal thickness, and the thickness of the plastic coating are also important features to be considered, and little, if any, thought on these features is evident from the prior art.
  • the metal occupies only about 14 percent of the silhouette of the area
  • l have now found that for proper results the spring steel should occupy a minimum of 17 percent of the silhouette of the area and, preferably, but less important, a maximum of about percent, with the range of about 17 percent to about 25 percent generally preferable.
  • the coating should generally be about one-half as thick as the wire, in order to give bridging, proper heat dissipation, and proper stretchability, but a range from about one-fifth of the wire thickness to about equal to the wire thickness can be used. Also, the size of the void areas between the coated wires should be no greater than about 75 percent of the seat area used to accommodate one adult sitter and should not be less than about 2 percent, with about 60 to 75 percent being preferable.
  • the present invention comprises a compactly stackable chair having a thin, spring-resilient seat and back.
  • each seat or back is a cylindrical segment, later flattened somewhat upon installation, placing the springs in tension.
  • it has a rim, which usually has straight ends, typically parallel, joined by parallel sides which are made as circular arcs, sometimes there is no rim.
  • each of the two extreme spring wires is tangent at each cycle to one of the rim sides, and each wire touches or closely approaches its adjacent sinuous spring wires at least once per cycle.
  • a first mounting means secures the seat assembly to the rigid side frame portions across a space that flattens its arc to a flatter arc and places the seat assembly in tension along the flatter cylindrical are, which is convex upwardly.
  • Second mounting means secures the back assembly to the rigid back frame portions across a space that flattens its arc to a flatter are which is convex rearwardly.
  • a thin sleevelike plastic coating surrounds both the rim wires (if they are present) and the sinous spring wires, following the sinuous shape of the spring wires and bridging between and joining them at points where they are tangent to each other or touch each other, and also joining and bridging between the rim and some positions of the wires.
  • This thin plastic coating while leaving most of the area of the seat open in between the wires, does link the wires and the rim together into a unitary assembly, shaped as a cylindrical arc. When the unitary assembly is installed on a frame as either a seat or a back, it is flattened out somewhat but not fully.
  • FIG. 2 is a view in perspective on an enlarged scale of a seat or back unit or sub-assembly embodying the principles of the invention, shown before being installed on the chair frame of FIG. 1.
  • FIG. 4 is a view in perspective of the fastener used in FIGS. 1 and 3 to secure the sub-assembly of FIG. 2 to the chair frame in FIG. 1.
  • FIG. 5 is a diagrammatic view in end elevation showing the difference in radii of the cylindrical assembly of FIG. 2 and the installed seat of FIG. 1, which has been somewhat flattened out, thereby placing the spring wires under tension.
  • FIG. 8 is a view in section taken along the line 8--8 in FIGS. 6 and 7.
  • FIG. 9 is a view in section taken along the line 9-9 in FIG. 7.
  • FIG. 12 is a view in side elevation of two chairs of FIG. 1 stacked. The seat of the upper chair and the back of the lower chair are broken away to show how the other seat and back nest.
  • FIG. 15 is an enlarged top plan diagrammatic view in two halves illustrating the two-way stretch effect of the wires and plastic assembly.
  • FIG. 16 is a fragmentary view in perspective of a portion of a modified form of seat assembly of the invention installedon a stacking chair as the seat thereof and showing a portion near a rear corner of the seat. Parts are broken away and shown in section. This view illustrates the adaptability of the invention to double curvature in the seat, as occasioned by curvature of the supporting frame.
  • a stacking chair 60 is shown in FIG. 1 for the purpose of giving one example of a type of seating unit that can embody the principles of the invention.
  • This example is not to be construed as representing all types of seating units or even all types of the chairs, which can vary greatly in frame structure, appearance, and so on.
  • the basic part of this invention is concerned with the seating and back unit and the stacking relationship mrffre than with the specific framework of the chair itse Compactly stackable chairs such as those shown in my US. Pat. No. Re. 26,071 may be used in conjunction with the present invention to provide a more resilient seat than the hard seat heretofore used with those chairs.
  • the chair frame may have curved lines, as discussed in connection with FIG.
  • the seats and backs are easily made so that they nest within each other when the chair frames are stacked, so long as the chairs themselves are of stackable structure.
  • Any type of stackable structure may be used with these seats and backs, and since they are quite thin, a compactly stackable structure becomes feasible with the stacking height of a set of chairs being determined basically by the thickness of the chair frames.
  • These chair frames if desired, may be made quite thin.
  • FIGS. 13 and 14 show how the seats and backs stack one within the other. It will be seen that the chord across the arc of the one chair intercepts the arc of the next adjacent chair. The same basic configuration also applies to the seats.
  • the chair 60 has front legs 61, 62 and rear legs 63 and 64 which are wider apart than the front legs 61, 62
  • bracing members are not significant in the present invention, though a rear bracing member 69 that is continuous with the members 67 and 68 and a front bracing member 69a are shown in the drawing, and there must be some rigid means for holding the frame members 67 and 68 apart and for holding the frame members 65 and 66 apart.
  • the back frame members 65 and 66 are rigidly held parallel to each other and the side frame members 67 and 68 are rigidly held parallel to each other.
  • This parallelism need not always be present, but it is preferred, as is one way of assuring stackability in the structure shown. In any event, the chairs should be stackable as compactly as the frame members themselves will permit.
  • a seat unit 70 is supported by the side frame members 67 and 68 and a back unit 70A is supported by the frame members 65 and 66.
  • the seat unit 70 and the back unit 70A are very similar to each other; they may in some instances be identical, but usually the back unit 70A is somewhat smaller than the seat unit 70 and is usually made from a smaller gauge of wire.
  • the structure of the units 70 and 70A is highly important in this invention. So is the attachment of the units 70 and 70A to a chair frame.
  • the Seat Unit 70 (FIG. 2)
  • FIG. 2 shows the seat unit 70 before it is incorporated into the chair; the view also represents basically what the unit 70A looks like, although the unit 70A may be different in size or even in structure or appearance, where desired.
  • the unit 70 comprises a rim 7! having spaced-apart straight ends 72 and 73 joined by parallel side members 74 and 75, which are shaped as circular arcs.
  • the member 74 which is to extend across the front edge of the seat, may be of thinner gauge than the wires 76, etc., in the remainder of the seat.
  • the straight end members 72 and 73 are secured to the side frame members 67 and 68 of the chair, and thus extend from front to rear at each side of the chair 60, while the side members 74 and 75 become the front and back edges of the seat in the assembled chair 60.
  • the members 72 and 73 are the ends and the side members 74 and 75 are arcuate or circular sides. As shown in FIG. 16, there need be no rim 7] or members 72 or 73.
  • These springs 76, 760, etc. may have many shapes, some of which are shown in the parent application. They may be of the type often called non-sagging springs and sometimes sold under the trademark No-Sag.
  • Typical wires 76, etc., of this type are of spring steel, having 0.60 to 0.75 percent carbon and 0.90 to 1.20 percent manganese.
  • Tensile strength typically runs about 215,000 to 265,000 p.s.i., and their Rockwell hardness is about 39-41 RC range.
  • the diameter of the wires 76, etc. preferably lies in the range of 0.05 inch to 0.l5 inch. Too thick a wire tends to concentrate the stiffness too much and the seat is too firm, while too thin a wire makes the seat too soft. Some of the wires 76, etc., may be thinner than others, especially toward the front of the seat. Some of the wires may have different vibration frequencies than others, some may be thicker to snub vibration. Some wires may be of different arc-cycle length than others, or some may be of different temper from others, to accomplish this purpose of snubbing vibrations.
  • each end 77, 78 of each spring (See FIGS. 6-10) is firmly anchored to and secured to one of the end members 72, 73 of the rim 7].
  • Various means are employed to achieve this firm anchorage, and some of these are described below in following sections. They include friction grips and welding, among the many types of mechanical connections.
  • the spring members 76, 76a, 76b, 76n are placed tangent to each other, each of the two extreme spring wires 76 and 76n being substantially tangent at each cycle to one of the side members 74 and 75.
  • Each wire 76 touches its adjacent wires at least once per cycle. The touching may be actual contact or it may be approximate touching or close approach, because, as will be seen, the assembly 70 is held together in a way that does not require actual physical contact of the metal at each tangent point, but it is always a very close relationship if not an actual touching.
  • a thin sleevelike plastic coating 79 surrounds the spring wires 76, follows their sinuous shape, and bridges the wires 76, 76a, etc., where they substantially touch each other.
  • the plastic coating 79 is about one-half of the wire thickness, or in the range of about one-fifth of the wire thickness to about equal to the wire thickness. At the junctures, the thickness may be mostly greater, though the wires themselves may touch each other.
  • This plastic coating 79 also surrounds the rim 71 and links the wires 76 and the end and side members of the rim 71 together into the unitary assembly 70.
  • the securing means may be an integral part of the unit 70, or may be an integral part of the chair frame or other frame to which the unit 70 is to be secured, or it may be an independent member not an integral part of either of these.
  • An example of the last-mentioned type is the securing member 80 shown in FIGS. 3 and 4. This may be a suitable metal or plastic member having a generally tubular rim-receiving portion 81, with an opening 82 therethrough that fits snugly around a rim member 72 or 73.
  • the member 80 has a pair of flanges 83, 84 having an opening 85 through them.
  • the chair frame member 67 may have a series of openings 86.
  • a suitable screw 87 may be inserted through a suitable opening 88 of the frame member 67 and secured by means of the openings 85 to the wings 83 and 84. As shown in FIG. 1, there may be several of these units 80 to secure the seat unit 70 and the back unit 70A to the chair 60.
  • the assembly 70 and the assembly 70A may be made as units by one manufacturer and sold to another manufacturer who makes the chair frames. So long as the dimensioning is correct, the two manufacturers need not know precisely what each other is doing, for the unit 70, if made in the correct dimensions, can be secured to a variety of different types of chair frames, or to other frames of seating members, for that matter, including benches, automobile frames, and so on.
  • the unit 70 enables the chair manufacturer to secure the seat or back in place in the most attractive and pleasing and most practical way.
  • FIG. 5 shows diagrammatically what happens when the unit 70 of FIG. 2 is put into the chair 60 of FIG. I.
  • the round cylindrical arc of FIG. 2 with radius R1 is flattened from the shape shown at the bottom of FIG. 5 to the shape shown at the top of FIG. 5, where it has a larger radius R2.
  • the unit 70 then has a broader span and its arc is somewhat flattened. so that it can be used as a seat. It has a crown height h, shown on the drawing, and it is still a cylindrical arc, though much flatter.
  • This flattening of a round assembly is an important feature of the invention.
  • the unit 70 By forming the unit 70 initially as a cylindrical arc, which is quite round and fairly well closed, and then flattening it considerably, a large amount of desirable tension is placed into the completed unit 70, so that the seat has a springy feel to it, acting substantially as though there was a large cushion instead of simply an assembly of thin springs.
  • the exact amount of crown height h or of curvature depends, of course, somewhat on taste, but generally there will be about a maximum of one-inch crown height h in a sixteen-inch wide seating unit 70, and the proportion is usually best considered as being. a crown height h of one-sixty-fourth to one-sixteenth of the span.
  • the amount of force required to flatten a seat of typical dining chair size is important as well.
  • a collection of springs in an assembly 70 requiring a force of between 340 pounds and 680 pounds to flatten it gives a seat of proper tension, (preferably around 500 pounds). This is the force exerted in pulling the two ends 72, 73 apart to be of an appropriate distance to fit onto the chair frame members 67, 68.
  • the plastic coating 79 may be chosen from various types of plastic, such as polyvinyl chloride, polyvinyl acetate mixtures thereof, other vinyl compounds, polyethylene, butadiene, acrylic elastomers, and so on.
  • the material may be transparent, where that is desired, or may be opaque and impart its own color to the unit. It may contain dye or pigment which imparts a desired color, completely preventing view of the wires 76 themselves and giving the appearance of constituting the actual seating material.
  • the plastic coating 79 may be semi-transparent and may give shade or tone to the overall color.
  • the plastic is confined to the unit or 70A and is not applied at all to the chair frame, so that the chair frame may have any surface or treatment that is desired without interference from the nature of the plastic coating.
  • the sinuous wires 76 are preferably not welded to each other at their points of tangency but are held together only by the plastic coating 79, with the wires 76 either touching each other or even slightly apart but closely approaching each other. The same is true of the connection between the wires 76 and the arcuate side members 74 and 75 of the rim 71.
  • the plastic coating 79 is that by choosing the proper range of durometer, a two-way stretch effect can be obtained, as illustrated in FIG. 15.
  • the springs 76 not only stretch in the well known manner of non-sagging springs, but also the plastic coating 79 between the adjacent springs 76 may be stretched, and this two-way stretch effect gives a wide range of resilience to the seat. If the plastic 79 is too hard, there can be substantially no such stretch, and if the plastic 79 is too soft, there will be too much stretch, the springs 76 themselves are not properly availed of, and
  • the unit 70 might even be torn apart after short use.
  • the effect is right, with sufficient rigidity so that the springs 76 are taken advantage of and so that they are held apart with sufficient resilience so that the whole is not simply encased in a rigid covering.
  • the durometer range necessary to achieve this critical action is from about 45 to about 90 Shore A-scale durometer, with a preferable value of about 75.
  • FIG. there are two portions.
  • the left portion illustrates part of a seat 70 before it is sat upon, with the springs 76 therefore in their normal configuration.
  • a typical area 280 is shown outlined, this area comprising one complete cycle of wires 76, so that it is representative of the total area of the seat 70 so far as the percentage of metal silhouette per total area is concerned.
  • This area can therefore be used for determining accurately the silhouette of the wire and its average occupation of the seat area.
  • the gauge or wire diameter as G
  • the length of the wire can be determined in terms of G by measuring the length of the center lines of all the wires 76 in the area 280 in terms of G, and the value is found to be 340.
  • the area 280 itself measures 14.60 by 10.70, which is 156.220
  • the silhouette area of the wire in the area 280 is 340 which is 21.76 percent of the area 280. This value lies within the required range of l7 to about 75 percent of the seat area, mentioned earlier, and also within the range of the preferred range of 17 to about 25 percent.
  • the empty spaces between the coated wires should be no greater than about 75 percent and no less than about 2 percent of the area of the seat surface, and the range of about 60 to about 75 percent is preferred. The minimum of about 2 percent barely provides sufficient air ventilation.
  • the wires 76 in the seat 70 lie closely adjacent each other and nearly touch at points of near-tangency, where the distance D] between them, as shown in FIG. 39, may be as low as zero, and where the overall distance from the outside to the outside is TI.
  • the plastic coating 79 forms a bridge fastening the wires 76 together at 281 and has a thickness t.
  • the right portion of FIG. 15 illustrates what happens when the seat 70 is stretched, as when it is sat upon.
  • the length L1 in the left portion extends to the longer length L2 in the right portion.
  • the width Wl in the left portion extends also to become the width W2 in the right portion.
  • the distance D1 in the left portion has stretched to become the distance D2 in the right portion, and the distance T1 has stretched to become the distance T2.
  • the empty spaces constitute at least 2 percent of the seat area, in order to give sufficient air ventilation, and preferably occupy much more of the seat area, up to about 75 percent.
  • the wire 76 is not exposed bare metal, which would be highly heat conductive and therefore unpleasant and uncomfortable.
  • the wire 76 is adequately coated with plastic 79 which is low in heat conductivity; so it is pleasant and comfortable to sit upon.
  • the coating 79 lies within the range of Shore A durometers (45-90) where it is neither too hard nor too soft; in fact it tends in itself to provide some cushioning effect, and its action at the bridges 281 adds to the comfort. Without this, the seat could be too hard or too soft.
  • the two-way stretch discussed above provides automatic contouring, offering minimal resistance to the human posterior. Without this two-way stretch, the seat 70 might become increasingly uncomfortable.
  • Friction Fastening of the Wires to the Rim While many means of fastening the spring 76 to the rim 71 may be employed, some are naturally preferred above others. The preference depends on many factors, such as manufacturers capabilities and preferments, specifications given by customers, and various features of cost and capital equipment required.
  • the rim 71 has end members 72 and 73 that are generally tubular; they may be made as a solid tube, but, preferably, as shown in the drawings, each member 72 or 73 is an open tube that may be made by curling a narrow strip of metal in a generally circular shape. As shown, the member 72 or 73 has a flat bottom portion 90 which is punched through at intervals to provide openings 91 and wings 92 and 93, extending at an angle such as about 30. Machines for making these on either a batch basis or on a substantially continuous basis are readily devised, so that the members 72 and 73 may be made as long strips cut into desired lengths.
  • the member 73 may be considered as being the same as the member 72, so that they are reversible; in other words, the same piece may be used in either direction and at either end of the rim.
  • bending in one direction in reversal is a possibility, but no such reversal or sense of direction is required when the wings 92 and 93 are made as shown.
  • a series of side openings or slots 94 provide an entryway for the wire end 77 or 78.
  • the wire end 77 or 78 is inserted in the opening 94 and then moved lengthwise of the member 72 or 73 until it is stopped by engaging one of the wings 92 or 93.
  • the wire 76 depresses the wing 92 (or 93) under pressure, but when it engages the end of the far wing 93 (or 92), it can progress no farther.
  • accurate positioning is assured, and this can be made to provide automatically the desired tangencies of the wires 76 with each other and with the side members 74 and 75 of the rim 71.
  • the wire end 77 or 78 cannot be retracted, because on retraction, the depressed wing 92 (or 93) digs into the wire 76 and prevents outward movement.
  • the intention is to prevent any relative movement between the wire end 77 or 78 and the member 72 or 73 after assembly.
  • the wire 76 can move across a depressed wing 92 in the direction toward a stop wing 93 but cannot move back against the wing 92, once it has been moved in. As shown in FIGS. 7 and 10, the movement can be in either direction with the same effect exactly; it may be, of course, in opposite directions at opposite ends of the rim 71.
  • the plastic coating 79 is applied after this assembly is completed.
  • a frame member 100 is provided with a securing member 101 which is a cylindrical segment, as seen in cross section, and has a main body portion 102 that may be welded to the frame member 100, a similar one being welded to the opposite frame member, not shown here.
  • a series of projecting tongues 103 are provided, which may be initially made in a bent-up'position and then bent down into place as shown in FIG. 16, after the wire ends 77 or 78 have been approximately positioned so as to lock the wire ends 77 or 78 into place firmly by the members 103, clamping them between the members 103 and the frame 100. As shown in FIG. 16, this may extend along a curve, or it may extend along a straight line.
  • a stacking chair including in combination:
  • a frame having at least two spaced-apart rigid side frame portions, two front legs, two rear legs, and two spacedapart rigid back frame portions, said front legs and said rear legs being spaced apart at different distances and being operatively connected with their respective frame portions to enable compact stacking,
  • a seat assembly and a back assembly each having a series of arcuate, continuous, sinuous wires, each having two ends, each said wire closely approaching each of its immediately adjacent said wires at frequent intervals, and a thin sleevelike stretchable plastic coating surrounding said wires, following the sinuosity of said wires and joining said wires together where they closely approach each other, said approaches being close enough for effective bridging between them by said coating, whereby said wires and plastic coating comprise a unitary assembly defining a cylindrical are,
  • first mounting means for securing said seat assembly to said rigid side frame portions across a space that flattens said arc to a flatter arc and places said seat assembly in tension along the flatter cylindrical arc, which is convex upwardly, and
  • each said seat assembly when a plurality of said chairs are stacked, nesting over said seat assembly of the chair below, with part of the lower surface of each lower seat assembly lying within the chord across the seat assembly of said chair im mediately above, the back assemblies being similarly nested.
  • each said assembly includes:
  • a rim defining a closed area of a cylindrical surface arched in one direction and straight in another direction normal to said arched direction, and having springy flexing action along said arched direction,
  • said series of sinuous wires each being positively anchored at opposite ends to said rim and extending across said rim in a generally circular are parallel to the arching of said rim, the longitudinal axes of said wires being parallel to each other,
  • said thin sleevelike plastic coating surrounding said rim linking said wires to said rim in a unitary assembly shaped as a cylindrical arc having a curvature of less radius than that desired in said seat or back.
  • the stacking chair of claim 2 having means for mounting said rim on said frame members, and for flattening said wires somewhat to place the wires in tension along said flatter cylindrical are.
  • each said assembly having mounting means for securing, separate from said coating, each said assembly to its said rigid frame portions, thereby preventing relative sliding movement of said wires therealong, said frame portions being so spaced apart that installation flattens said are to a flatter arc and places the assembly in tension.
  • said mounting means comprises means for anchoring each of said wires adjacent their ends, the tension under which the wires are placed helping to retain them in place.
  • each said mounting'means engages the actual wire ends to prevent movement of the two ends of each said wire toward each other.
  • said mounting means comprises a member having transversely outwardly extending tongues to which said wire ends are engaged, said tongues being bent down over said wires.

Abstract

A compactly stacking chair with a spring-resilient seat. The chair has a frame constructed to enable compact stacking. It also has a seat assembly and a back assembly, each having a series of arcuate, continuous, sinuous wires, each wire closely approaching each of its immediately adjacent wires at frequent intervals, and a thin sleevelike plastic coating surrounding the wires, following their sinuosity and joining the wires together where they closely approach each other. The approaches are close enough for effective bridging between them by the coating, and the wires and plastic coating comprise a unitary assembly defining a cylindrical arc. The seat and back assemblies are each secured to rigid frame portions across a space that flattens their arcs to flatter arcs and places these assemblies in tension along their flatter cylindrical arcs, the seat arc being convex upwardly, and the back arc being convex rearwardly. When a plurality of these chairs is stacked, each seat nests over the seat of the chair below, and the backs nest too with part of the lower surface of each seat lying within the chord across the seat of the chair above and part of the forward surface of each back lying within the chord across the back of the chair below.

Description

iinited States Patent 11 1 Rowland Nov. 5, 1974 STACKABLE SEATING UNITS [57] ABSTRACT [76] Inventor: David L. Rowland, 8 E. 62nd St., A compactly stacking chair with a spring-resilient seat. New York, N.Y. 10021 The chair has a frame constructed to enable compact [22] Filed: Sept. 7, 1973 itlacking. It also has a seat assembly and a back assemy, each havmg a series of arcuate, contmuous, sinuppl- -I 395,266 ous wires, each wire closely approaching each of its Related US Application Data immediately adjacent wires at frequent intervals, and a thm sleevehke plastic coatmg surrounding the wires, [60] F' W FF 268'8701 July 31 following their sinuosity and joining the wires together of 9 3 March where they closely approach each other. The apat. No. 3,720,568, Contmuatron-m-part of Ser. No. 268,907, July 3, 1972, which is a division of Proaches are close 9 for 'l brdgmg Ser 126,563, March 22 1971 tween them by the coatmg, and the wires and plastic coating comprise a unitary assembly defining a cylin- U-S. Cl. d ica] arc The seat and back assemblies are each se- [5 Int. Cl. ufgd to frame portions across a space that flat. Field of Search 297/239, 445, 450, 452, tens their arcs to flatter arcs and places these assem- 297/454 458; 160/403 404; 5/ 354; blies in tension along their flatter cylindrical arcs, the 2 a. c... 9 17/ 21511 112, 2 seat are being convex upwardly, and the back are 267/107-51 being convex rearwardly. When a plurality of these chairs is stacked, each seat nests over the seat of the References Cited chair below, and the backs nest too with part of the UNITED STATES PATENTS lower surface of each seat lying within the chord 2,731,076 1/1956 Rowland 297/452 x across the Seat of the chair above and P of the 2,s03,293 8/1957 Rowland 297/445 x a d rface f each back lying within the chord 3,404,916 10/1968 Rowland 297/239 across the back of the chair below. 3,708,202 1/1973 V V V V Primary ExaminerBobby R. Gay
Assistant Examiner-William E. Lyddane Attorney, Agent, or FirmOwen, Wickersham & Erickson Barecki et al 297/335 X 15 Claims, 16 Drawing Figures 'PATENTEUNOY 519M 3.845386 sum 2w 4 II/II/Il/II III/I/lll/I/II/II 1/11 I 0,, llllli m (Ill l-;qllllllllllll 1114 I- i'lllllllllli VIII; a!!! FEM STACKABLE SEATING UNITS CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of application Ser. No. 268,870, filed July 3, i972, which was a division of application Ser. No. l26,808, filed Mar. 22, l97l, now U.S. Pat. No. 3,720,568.
This application is also a continuation-in-part of application Ser. No. 268,907, filed July 3, 1972, which was a division of application Ser. No. 126,563, filed Mar. 22, 1971.
BACKGROUND OF THE lNVENTlON pactness in stacking. The non-resilient stacking chairs may be compactly stackable, with seats and backs thinner than the frame, but they lack the comfort-giving feature of spring resilience.
Thus, the present invention is characterized by spring-resilient seats and backs that are truly thin-- -thinner than the frame.
The term, spring resilience, is here used to distinguish the present seat from canvas sling seats and backs and the like.
A hard seat can, at best, only approximate a comfortable shape, since human posteriors vary greatly. While seats theoretically might be tailor-made for each individual, this would be costly and would require carrying seats to wherever they would be used. A seat which automatically tends to shape itself to each users posterior is a better solution to the problem. A seat with proper resilience in the right places is thus an object of this invention.
The seated human body rests mainly on the ischial tuberosities, the two lower points of the pelvis. Additionally, it rests on the meaty and fatty flesh in a l to 2 inch radius therefrom. The reason why a flat, hard surface becomes uncomfortable quickly is that the load is concentrated on the small area of the ischial tuberosities', and the flesh immediately covering them is compressed with great force. Spreading this load over a larger area makes a more comfortable condition as the unit area compressive force is substantially reduced. Automatically shaping the seat surface to generally conform to the sitter helps to accomplish this. On the other hand, spreading this area over too wide a surface, such as is the case when a seat is too soft, results in engulfing the sitter too deeply and also often results in a lack of security, which comes from feeling insuffi ciently supported. One often sees automobiles in which the owner has gone to the trouble of installing wooden slat accessory pads to make the seat firmer.
Dr. Bengt Akerblom. eminent Swedish authority on human posture, says in his book Standing And Sitting Posture, published by A. B. Nordiska Bokhandeln, 1948, Naturally a rather soft seat would distribute the pressure over the tuberosities better than a hollowed rigid one. They are, however, so small that there would be very little sense in having a very soft and resilient seat. On the contrary, such a seat might be expected to transfer a not inconsiderable proportion of the weight on to tissues which are not adapted for bearing it. The best consistency for the seat would therefore be such that although it gave under pressure, it only gave slightly."
Proper resilience alone is not enough, either. lndependent freedom of movement of such as that found in a two-way stretchable material more appropriately confomis to the human posterior shape, which itself has compound curvature.
While certain spring and padding combinations can afford proper yieldability and firmness, practically all padding materials have the fault of being good heat insulators. In a cold room, this might be acceptable temporarily, but people usually wear clothes appropriate for temperature conditions anyway, and to sit for any length of time on a heat-insulative material becomes uncomfortable because of inhibition of dispersion of body heat in the human posterior area. To get to a cooler spot, the person squirms. Also, anyone who, while wearing a swim suit, has tried to sit down on the seat of a convertible car that has been out in the hot sun, knows that such heat conditions of the seat can be unbearable.
Some prior art seats have been made of spaced-apart wires, but in them the spacing has been such that too much load has been concentrated on too few wires, and this textural discomfort has made the use of upholstery pads requisite for such seats.
An ideal seat, therefore, has:
1. Proper shape (including proper compound curvature).
2. Proper resilience and firmness (resilience provides shape adaptability to each sitter).
3. Proper heat dispersion.
4. Proper surface contact area.
An object of this invention is to provide a seat for stacking chairs more nearly approaching the ideal than has been achieved in the past.
Each seat or back of this invention comprises a series of sinuous spring wires, partially held together by a thin sleevelike plastic coating around each of the wires, bridging the wires where they touch.
The seat and back structure may be considered as an improvement over my earlier U.S. Pat. No. 2,803,293. In that patent each of the sinuous springs had a hook on each end which partially encircled a rigid frame member. This hooking did not positively prevent movement of the wires relative to the frame, nor did it hold them in proper position relative to each other prior to their being coated with plastic. Partly because there was only line contact at best between the wire and the frame (and unless the chair frame size was exactly matched with the size of the hook, there would be contact at only two points), the hook tended to rotate when subjected to force, as when someone sat on the chair. Even after the chair had been coated with plastic, this instability was such that when the chair was being sat upon, the wire hooks tended to walk along the chair frame as the sitter shifted his position, thereby distorting the seat area, with the result of making the seat uncomfortable. Moreover, the chair of that patent was expensive to manufacture because the springs had to be put on individually, carefully positioned, and then either the entire chair had to be dipped, or at least the upper portion of the chair, from the seat up, had to be dipped. Such dipping meant that all parts of the chair that were dipped would be coated with plastic unless something could be put on some parts of the chair to repel the plastic. Either alternative added substantially to the cost. Also, the coating dulled the appearance of chrome metal furniture, and wood furniture was given a rather unpleasing appearance. Each chair had to be made individually, and the springs themselves had to be put on to a full chair frame individually, so that easy handling required by mass production was not possible. Also, great care had to be taken that the springs themselves were not distorted by the spring manufacturer during his manufacture; otherwise, the springs could not be properly bridged across by the plastic.
These difficulties are overcome in the present invention, which makes mass production quite feasible. Only the seat unit or back unit is dipped, and assembly is relatively inexpensive, and its manufacture is capable of automation and other mechanical aids.
Another disadvantage of my prior chair was that the chair seat and back were substantially planar, and, even if they did have a slight bowing, they were installed in a generally flat at-rest shape of the spring, so that there was little spring tension or cushioning action. In the present invention, it becomes possible to obtain much more tension, cushioning, and resilient support from the springs by virtue of making the unit as a cylindrical segment that is somewhat flattened when it is put on a chair frame, rather than making chairs from a series of substantially flat springs. The tension of the wires pulling inwardly is one of the main forces retaining the assembly in place.
Another important feature of the invention is the provision of a two-way stretch, which is obtained by using plastic coatings lying within a prescribed range of Shore durometers. The springs can continue their flexing in the usual manner without being overly limited by the coating, and also the spring assembly can flex and stretch the plastic when it bridges the wires.
Even two-way stretchability and proper wire gauge alone have been found to be insufficient. Resistance to bounciness is an important property when considering the resilience necessary for a comfortable seat and is especially necessary in transportation seating, where up-and-down motion tends to result in harmonic vibration, for harmonic vibrations subject the sitter to vertical oscillations for some time after a bump has been traversed. Bounce dampening is thus requisite, and is partly accomplished in the present invention by proper choice of durometer of the plastic coating. if the durometer is too low a value, the springs are too free and are too ready to bounce. If the durometer is too high,
. the seat is too stiff and lacks the proper two-way stretch quality desired. Proper choice of durometer according to the principles of this invention, enables the plastic to serve as a shock absorber and provides a snubbing action against bounce.
Additionally, bounce-dampening can be achieved in this invention by employing in the assembly some wires that differ from the other wires in gauge, shape, or spring tension or temper, so that their harmonic vibration periods are different.
The amount of the seating area occupied by the metal thickness, and the thickness of the plastic coating are also important features to be considered, and little, if any, thought on these features is evident from the prior art. For example, in the drawings for U.S. Pat. No. 2,803,293, it can be shown that the metal occupies only about 14 percent of the silhouette of the area, whereas l have now found that for proper results the spring steel should occupy a minimum of 17 percent of the silhouette of the area and, preferably, but less important, a maximum of about percent, with the range of about 17 percent to about 25 percent generally preferable. The coating should generally be about one-half as thick as the wire, in order to give bridging, proper heat dissipation, and proper stretchability, but a range from about one-fifth of the wire thickness to about equal to the wire thickness can be used. Also, the size of the void areas between the coated wires should be no greater than about 75 percent of the seat area used to accommodate one adult sitter and should not be less than about 2 percent, with about 60 to 75 percent being preferable.
SUMMARY OF THE INVENTION The present invention comprises a compactly stackable chair having a thin, spring-resilient seat and back. Basically, each seat or back is a cylindrical segment, later flattened somewhat upon installation, placing the springs in tension. Sometimes it has a rim, which usually has straight ends, typically parallel, joined by parallel sides which are made as circular arcs, sometimes there is no rim. There is a series of sinuous spring wires, each of which is attached at its opposite ends to the rim, if there is one. The wires extend between their ends in a circular are which, when there is a rim, is parallel to the circular arc of the parallel sides of the rim. In most seats and backs each of the two extreme spring wires is tangent at each cycle to one of the rim sides, and each wire touches or closely approaches its adjacent sinuous spring wires at least once per cycle.
More specifically, a stacking chair of this invention includes a frame having at least two spaced-apart rigid side frame portions, two front legs, two rear legs, and two spaced-apart rigid back frame portions. The frame portions and the legs are arranged to enable compact stacking. The frame supports both a seat assembly and a back assembly, each of which has a series of arcuate, continuous, sinuous wires, each wire closely approaching each of its immediately adjacent wires at frequent intervals. A thin sleevelike plastic coating surrounds the wires, following their sinuosity and joining them together where they closely approach each other, the approaches being close enough for effective bridging between them by the coating. Thus, the wires and the plastic coating are combined in a unitary assembly defining a cylindrical are. A first mounting means secures the seat assembly to the rigid side frame portions across a space that flattens its arc to a flatter arc and places the seat assembly in tension along the flatter cylindrical are, which is convex upwardly. Second mounting means secures the back assembly to the rigid back frame portions across a space that flattens its arc to a flatter are which is convex rearwardly. When a plurality of these chairs are stacked, each seat nests over the seat of the chair below, part of the lower surface of each lower seat lying within the chord across the seat of the upper chair; similarly, each back nests within the back of the chair below, part of the forward surface of each back lying within the chord across the back of the chair below.
A thin sleevelike plastic coating surrounds both the rim wires (if they are present) and the sinous spring wires, following the sinuous shape of the spring wires and bridging between and joining them at points where they are tangent to each other or touch each other, and also joining and bridging between the rim and some positions of the wires. This thin plastic coating, while leaving most of the area of the seat open in between the wires, does link the wires and the rim together into a unitary assembly, shaped as a cylindrical arc. When the unitary assembly is installed on a frame as either a seat or a back, it is flattened out somewhat but not fully. When used as a seat, the rise between one end and the other after flattening is between a quarter of an inch and an inch, preferably. For the back, the curvature may be somewhat greater, preferably a radius of seven to twenty inches. The plastic preferably is in the range of Shore A durometers between 45 and 90, and seems to be best at about 75, so that the two-way stretch action previously referred to is attained.
In some forms of the invention other shapes of rims are used, and in still other forms, no rim as such is necessary, being replaced by a special welded subassembly.
Note that in this invention the wires cannot go straight across. They must undulate in order to be stretchable. Moreover, they must be connected to each other by stretchable means. This contrasts with my earlier patent which may allow flexible joints but does not require stretchable joints. A ISO-pound person sitting normally on a chair of the present invention will depress it by at least 1 inch (or at least one-eighteenth part of seat height) and, at most by about 3 inches (about one-sixth part of seat height). As stated, the junctures are stretchable and flexible, but they are also so tough that they cannot be pulled apart under usual human sitting conditions. Putty and kneaded erasers have a rubbery quality, but not the elasticity, stretchability, flexibility or resilience requisite. To get the best results in this invention, the area of the silhouette of the wires prior to coating should be at least l7 percent of the seat area, especially of a typical area. For sufficient bridging, heat dissipation, and surface cushioning, the coating should be at least percent of the wire diameter. If the seat were made from springs alone, the comfort would be insufficient, particularly when used in moving vehicles. It would be too bouncy. Proper durometer and proper thickness of the coating relative to the wire thickness help to prevent this bounciness. The reason is similar to the reason why a car'is not comfortable with metal springs alone; it also needs the rubber, air, and hydraulic fluid in the combination of rubberpneumatic tires and hydraulic shock absorbers, before it can be comfortable.
BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:
FIG. 1 is a view in perspective of a stacking chair embodying the principles of the invention.
FIG. 2 is a view in perspective on an enlarged scale of a seat or back unit or sub-assembly embodying the principles of the invention, shown before being installed on the chair frame of FIG. 1.
FIG. 3 is a view in section taken along the line 3-3 in FIG. 1.
FIG. 4 is a view in perspective of the fastener used in FIGS. 1 and 3 to secure the sub-assembly of FIG. 2 to the chair frame in FIG. 1.
FIG. 5 is a diagrammatic view in end elevation showing the difference in radii of the cylindrical assembly of FIG. 2 and the installed seat of FIG. 1, which has been somewhat flattened out, thereby placing the spring wires under tension.
FIG. 6 is a fragmentary enlarged view in perspective of a corner portion of the assembly of FIG. 2, somewhat flattened out. Some portions are broken away to show other portions that would otherwise be obscured.
FIG. 7 is a further enlarged view in section taken along the line 7-7 in FIG. 6.
FIG. 8 is a view in section taken along the line 8--8 in FIGS. 6 and 7.
FIG. 9 is a view in section taken along the line 9-9 in FIG. 7.
FIG. 10 is a view like FIG. 7 showing how the springs may be installed from the opposite direction in the same rim unit.
FIG. 11 is a view in front elevation of the chair of FIG. 1.
FIG. 12 is a view in side elevation of two chairs of FIG. 1 stacked. The seat of the upper chair and the back of the lower chair are broken away to show how the other seat and back nest.
FIG. 13 is a diagrammatic view in section taken along the line A-A in FIG. 12.
FIG. 14 is a diagrammatic view in section taken along the line 8-8 in FIG. 12.
FIG. 15 is an enlarged top plan diagrammatic view in two halves illustrating the two-way stretch effect of the wires and plastic assembly.
FIG. 16 is a fragmentary view in perspective of a portion of a modified form of seat assembly of the invention installedon a stacking chair as the seat thereof and showing a portion near a rear corner of the seat. Parts are broken away and shown in section. This view illustrates the adaptability of the invention to double curvature in the seat, as occasioned by curvature of the supporting frame.
DESCRIPTION OF SOME PREFERRED EMBODIMENTS An Example of a Stacking Chair Embodying the Invention (FIG. 1)
Many, many types of seating units may embody the principles of this invention, including chairs, sofas, and davenports.
A stacking chair 60 is shown in FIG. 1 for the purpose of giving one example of a type of seating unit that can embody the principles of the invention. This example is not to be construed as representing all types of seating units or even all types of the chairs, which can vary greatly in frame structure, appearance, and so on. The basic part of this invention is concerned with the seating and back unit and the stacking relationship mrffre than with the specific framework of the chair itse Compactly stackable chairs such as those shown in my US. Pat. No. Re. 26,071 may be used in conjunction with the present invention to provide a more resilient seat than the hard seat heretofore used with those chairs. The chair frame may have curved lines, as discussed in connection with FIG. 16 by virtue of this invention, and the seats and backs are easily made so that they nest within each other when the chair frames are stacked, so long as the chairs themselves are of stackable structure. Any type of stackable structure may be used with these seats and backs, and since they are quite thin, a compactly stackable structure becomes feasible with the stacking height of a set of chairs being determined basically by the thickness of the chair frames. These chair frames, if desired, may be made quite thin.
FIGS. 13 and 14 show how the seats and backs stack one within the other. it will be seen that the chord across the arc of the one chair intercepts the arc of the next adjacent chair. The same basic configuration also applies to the seats.
The chair 60 has front legs 61, 62 and rear legs 63 and 64 which are wider apart than the front legs 61, 62
and continue up, preferably at an angle, to form back frame portions or members 65 and 66. The number of pieces used in making the chair frame is immaterial to this invention, and whether the frame is continuous or pieces are welded or otherwise secured together does not matter, so far as the present invention is concerned. Horizontal side frame portions or members 67 and 68, the same distance apart as the front legs 61, and 62, join the front legs 61 and 62 to the inner edges of the rear legs 63, 64, preferably at the point where the rear legs 63, 64 meet the back frame members 65 and 66. The use of bracing members is not significant in the present invention, though a rear bracing member 69 that is continuous with the members 67 and 68 and a front bracing member 69a are shown in the drawing, and there must be some rigid means for holding the frame members 67 and 68 apart and for holding the frame members 65 and 66 apart. in this particular form of the invention the back frame members 65 and 66 are rigidly held parallel to each other and the side frame members 67 and 68 are rigidly held parallel to each other. This parallelism need not always be present, but it is preferred, as is one way of assuring stackability in the structure shown. In any event, the chairs should be stackable as compactly as the frame members themselves will permit.
A seat unit 70 is supported by the side frame members 67 and 68 and a back unit 70A is supported by the frame members 65 and 66. The seat unit 70 and the back unit 70A are very similar to each other; they may in some instances be identical, but usually the back unit 70A is somewhat smaller than the seat unit 70 and is usually made from a smaller gauge of wire.
The structure of the units 70 and 70A is highly important in this invention. So is the attachment of the units 70 and 70A to a chair frame.
The Seat Unit 70 (FIG. 2)
FIG. 2 shows the seat unit 70 before it is incorporated into the chair; the view also represents basically what the unit 70A looks like, although the unit 70A may be different in size or even in structure or appearance, where desired.
in this example the unit 70 comprises a rim 7! having spaced-apart straight ends 72 and 73 joined by parallel side members 74 and 75, which are shaped as circular arcs. The member 74, which is to extend across the front edge of the seat, may be of thinner gauge than the wires 76, etc., in the remainder of the seat. Lest there be some confusion in the mind of the reader, it is pointed out that the straight end members 72 and 73 are secured to the side frame members 67 and 68 of the chair, and thus extend from front to rear at each side of the chair 60, while the side members 74 and 75 become the front and back edges of the seat in the assembled chair 60. However, so far as the seat unit 70 itself is concerned, the members 72 and 73 are the ends and the side members 74 and 75 are arcuate or circular sides. As shown in FIG. 16, there need be no rim 7] or members 72 or 73.
Extending from end to end across the two end members 72 and 73 is a plurality of sinuous spring wires 76, 76a, 76b 76n, which are naturally arched into a circular arc of the same size and shape as that of the side members 74 and 75. These springs 76, 760, etc., may have many shapes, some of which are shown in the parent application. They may be of the type often called non-sagging springs and sometimes sold under the trademark No-Sag. Typical wires 76, etc., of this type are of spring steel, having 0.60 to 0.75 percent carbon and 0.90 to 1.20 percent manganese. Tensile strength typically runs about 215,000 to 265,000 p.s.i., and their Rockwell hardness is about 39-41 RC range. The diameter of the wires 76, etc., preferably lies in the range of 0.05 inch to 0.l5 inch. Too thick a wire tends to concentrate the stiffness too much and the seat is too firm, while too thin a wire makes the seat too soft. Some of the wires 76, etc., may be thinner than others, especially toward the front of the seat. Some of the wires may have different vibration frequencies than others, some may be thicker to snub vibration. Some wires may be of different arc-cycle length than others, or some may be of different temper from others, to accomplish this purpose of snubbing vibrations.
Each end 77, 78 of each spring (See FIGS. 6-10) is firmly anchored to and secured to one of the end members 72, 73 of the rim 7]. Various means are employed to achieve this firm anchorage, and some of these are described below in following sections. They include friction grips and welding, among the many types of mechanical connections.
The spring members 76, 76a, 76b, 76n are placed tangent to each other, each of the two extreme spring wires 76 and 76n being substantially tangent at each cycle to one of the side members 74 and 75. Each wire 76 touches its adjacent wires at least once per cycle. The touching may be actual contact or it may be approximate touching or close approach, because, as will be seen, the assembly 70 is held together in a way that does not require actual physical contact of the metal at each tangent point, but it is always a very close relationship if not an actual touching.
A thin sleevelike plastic coating 79 surrounds the spring wires 76, follows their sinuous shape, and bridges the wires 76, 76a, etc., where they substantially touch each other. Preferably, the plastic coating 79 is about one-half of the wire thickness, or in the range of about one-fifth of the wire thickness to about equal to the wire thickness. At the junctures, the thickness may be mostly greater, though the wires themselves may touch each other. This plastic coating 79 also surrounds the rim 71 and links the wires 76 and the end and side members of the rim 71 together into the unitary assembly 70. The plastic coating 79 holds the wires 76 to each other as they span between the rim ends 72 and 73, and it holds the side wires 74 and 75 to the extreme springs 76 and 76n at each point of tangency. The result is the arcuate or cylindrical arc shape, typically like that shown in FIG. 2, although the arc may be somewhat flatter or somewhat rounder Thus, the complete assembly 70 is a unit which can be sold or shipped as a unit and can be assembled to the chair 60 of FIG. 1 or to many other kinds of chairs, so long as the proper size and shape is accommodated for in one way or another, that is, either by the chair itself being shaped to go with the seat unit 70 or the seat unit 70 itself made so that it will go with a chair frame or other type of seating unit frame. The unit 70 by itself is capable of mass production, and is easily assembled into a chair or other seating unit by securing the two end members 72 and 73 to a suitable rigid frame.
An Independent Type of Securing Means (FIGS. 3 and Various securing means may be used, as described in the parent applications. Basically, the securing means may be an integral part of the unit 70, or may be an integral part of the chair frame or other frame to which the unit 70 is to be secured, or it may be an independent member not an integral part of either of these. An example of the last-mentioned type is the securing member 80 shown in FIGS. 3 and 4. This may be a suitable metal or plastic member having a generally tubular rim-receiving portion 81, with an opening 82 therethrough that fits snugly around a rim member 72 or 73. The member 80 has a pair of flanges 83, 84 having an opening 85 through them. As shown in FIG. 3, the chair frame member 67 may have a series of openings 86.
adapted to receive the two wings 83 and 84, after the member 80 has been fastened around the rim member 72 or 73. Then a suitable screw 87 may be inserted through a suitable opening 88 of the frame member 67 and secured by means of the openings 85 to the wings 83 and 84. As shown in FIG. 1, there may be several of these units 80 to secure the seat unit 70 and the back unit 70A to the chair 60.
From this it will be apparent that the assembly 70 and the assembly 70A may be made as units by one manufacturer and sold to another manufacturer who makes the chair frames. So long as the dimensioning is correct, the two manufacturers need not know precisely what each other is doing, for the unit 70, if made in the correct dimensions, can be secured to a variety of different types of chair frames, or to other frames of seating members, for that matter, including benches, automobile frames, and so on. The unit 70 enables the chair manufacturer to secure the seat or back in place in the most attractive and pleasing and most practical way.
As will be seen from later portions of the specification, there are many, many ways in which the fastening of the member 70 to the chair 60 can be done, and this is just one example. The Significance of Flattening the Cylindrical Arc (FIG. 5)
FIG. 5 shows diagrammatically what happens when the unit 70 of FIG. 2 is put into the chair 60 of FIG. I. The round cylindrical arc of FIG. 2 with radius R1 is flattened from the shape shown at the bottom of FIG. 5 to the shape shown at the top of FIG. 5, where it has a larger radius R2. The unit 70 then has a broader span and its arc is somewhat flattened. so that it can be used as a seat. It has a crown height h, shown on the drawing, and it is still a cylindrical arc, though much flatter.
This flattening of a round assembly is an important feature of the invention. By forming the unit 70 initially as a cylindrical arc, which is quite round and fairly well closed, and then flattening it considerably, a large amount of desirable tension is placed into the completed unit 70, so that the seat has a springy feel to it, acting substantially as though there was a large cushion instead of simply an assembly of thin springs. The exact amount of crown height h or of curvature depends, of course, somewhat on taste, but generally there will be about a maximum of one-inch crown height h in a sixteen-inch wide seating unit 70, and the proportion is usually best considered as being. a crown height h of one-sixty-fourth to one-sixteenth of the span.
The amount of force required to flatten a seat of typical dining chair size is important as well. For purposes of the present invention it has been found that a collection of springs in an assembly 70, requiring a force of between 340 pounds and 680 pounds to flatten it gives a seat of proper tension, (preferably around 500 pounds). This is the force exerted in pulling the two ends 72, 73 apart to be of an appropriate distance to fit onto the chair frame members 67, 68.
For the chair back, somewhat different rules apply and it will be noticed that in the chair of FIG. 1, as in most such chairs, the arc of the back extends rearwardly and is not something that the sitter tends to flatten; rather, he tends to increase the arc curvature, reducing its radius.
In both the seat and the back, the tension of the wires pulling inwardly, which results from flattening, is also one of the main forces retaining the wires in place. Significance of the Plastic Coating 79 (FIG. 15)
The plastic coating 79 may be chosen from various types of plastic, such as polyvinyl chloride, polyvinyl acetate mixtures thereof, other vinyl compounds, polyethylene, butadiene, acrylic elastomers, and so on. The material may be transparent, where that is desired, or may be opaque and impart its own color to the unit. It may contain dye or pigment which imparts a desired color, completely preventing view of the wires 76 themselves and giving the appearance of constituting the actual seating material. The plastic coating 79 may be semi-transparent and may give shade or tone to the overall color.
It will be noticed that in this invention the plastic is confined to the unit or 70A and is not applied at all to the chair frame, so that the chair frame may have any surface or treatment that is desired without interference from the nature of the plastic coating.
The sinuous wires 76 are preferably not welded to each other at their points of tangency but are held together only by the plastic coating 79, with the wires 76 either touching each other or even slightly apart but closely approaching each other. The same is true of the connection between the wires 76 and the arcuate side members 74 and 75 of the rim 71.
An important feature of the plastic coating 79 is that by choosing the proper range of durometer, a two-way stretch effect can be obtained, as illustrated in FIG. 15. The springs 76 not only stretch in the well known manner of non-sagging springs, but also the plastic coating 79 between the adjacent springs 76 may be stretched, and this two-way stretch effect gives a wide range of resilience to the seat. If the plastic 79 is too hard, there can be substantially no such stretch, and if the plastic 79 is too soft, there will be too much stretch, the springs 76 themselves are not properly availed of, and
the unit 70 might even be torn apart after short use. By
holding the Shore durometer of the plastic coating within critical values, the effect is right, with sufficient rigidity so that the springs 76 are taken advantage of and so that they are held apart with sufficient resilience so that the whole is not simply encased in a rigid covering. I have found that the durometer range necessary to achieve this critical action is from about 45 to about 90 Shore A-scale durometer, with a preferable value of about 75.
In FIG. there are two portions. The left portion illustrates part of a seat 70 before it is sat upon, with the springs 76 therefore in their normal configuration. A typical area 280 is shown outlined, this area comprising one complete cycle of wires 76, so that it is representative of the total area of the seat 70 so far as the percentage of metal silhouette per total area is concerned. This area can therefore be used for determining accurately the silhouette of the wire and its average occupation of the seat area. Taking the gauge or wire diameter as G, the length of the wire can be determined in terms of G by measuring the length of the center lines of all the wires 76 in the area 280 in terms of G, and the value is found to be 340. The area 280 itself measures 14.60 by 10.70, which is 156.220 The silhouette area of the wire in the area 280 is 340 which is 21.76 percent of the area 280. This value lies within the required range of l7 to about 75 percent of the seat area, mentioned earlier, and also within the range of the preferred range of 17 to about 25 percent.
Also, the empty spaces between the coated wires should be no greater than about 75 percent and no less than about 2 percent of the area of the seat surface, and the range of about 60 to about 75 percent is preferred. The minimum of about 2 percent barely provides sufficient air ventilation.
The wires 76 in the seat 70 lie closely adjacent each other and nearly touch at points of near-tangency, where the distance D] between them, as shown in FIG. 39, may be as low as zero, and where the overall distance from the outside to the outside is TI. The plastic coating 79 forms a bridge fastening the wires 76 together at 281 and has a thickness t.
The right portion of FIG. 15 illustrates what happens when the seat 70 is stretched, as when it is sat upon. The length L1 in the left portion extends to the longer length L2 in the right portion. The width Wl in the left portion extends also to become the width W2 in the right portion. The distance D1 in the left portion has stretched to become the distance D2 in the right portion, and the distance T1 has stretched to become the distance T2. Thus is seen the importance of the bridge or juncture 281 and of the stretchability of the plastic 79 at this bridge or juncture 281. This, of course, is related also to the thickness t of the plastic coating 79.
A glance at the seat 70 might lead one to conclude that the surface configuration would be texturally uncomfortable. However, this conclusion would be mistaken, for the seat 70 acts differently than one might at first conclude, for the following reasons:
1. The average occupation by the wire of the typical area (Le, 17 to 75 percent) is so great that the human posterior is supported without concentrating the load too much. In contrast, if the wire occupies less than about 17 percent of the area (e.g., the 14.4 percent occupation of the FIG. 2 area in US. Pat. No. 2,803,293), the seat would be texturally uncomfortable.
2. The empty spaces constitute at least 2 percent of the seat area, in order to give sufficient air ventilation, and preferably occupy much more of the seat area, up to about 75 percent.
3. The wire 76 is not exposed bare metal, which would be highly heat conductive and therefore unpleasant and uncomfortable. The wire 76 is adequately coated with plastic 79 which is low in heat conductivity; so it is pleasant and comfortable to sit upon.
4. The coating 79 lies within the range of Shore A durometers (45-90) where it is neither too hard nor too soft; in fact it tends in itself to provide some cushioning effect, and its action at the bridges 281 adds to the comfort. Without this, the seat could be too hard or too soft.
5. The two-way stretch discussed above provides automatic contouring, offering minimal resistance to the human posterior. Without this two-way stretch, the seat 70 might become increasingly uncomfortable.
Friction Fastening of the Wires to the Rim (FIGS. 6-10) While many means of fastening the spring 76 to the rim 71 may be employed, some are naturally preferred above others. The preference depends on many factors, such as manufacturers capabilities and preferments, specifications given by customers, and various features of cost and capital equipment required.
One desirable type of fastening employs afriction lock principle, shown in FIGS. 6-10. In this form, the rim 71 has end members 72 and 73 that are generally tubular; they may be made as a solid tube, but, preferably, as shown in the drawings, each member 72 or 73 is an open tube that may be made by curling a narrow strip of metal in a generally circular shape. As shown, the member 72 or 73 has a flat bottom portion 90 which is punched through at intervals to provide openings 91 and wings 92 and 93, extending at an angle such as about 30. Machines for making these on either a batch basis or on a substantially continuous basis are readily devised, so that the members 72 and 73 may be made as long strips cut into desired lengths.
As will be seen by comparing FIGS. 7 and 10, the member 73 may be considered as being the same as the member 72, so that they are reversible; in other words, the same piece may be used in either direction and at either end of the rim. Of course, bending in one direction in reversal is a possibility, but no such reversal or sense of direction is required when the wings 92 and 93 are made as shown.
A series of side openings or slots 94 provide an entryway for the wire end 77 or 78. The wire end 77 or 78 is inserted in the opening 94 and then moved lengthwise of the member 72 or 73 until it is stopped by engaging one of the wings 92 or 93. When inserted, the wire 76 depresses the wing 92 (or 93) under pressure, but when it engages the end of the far wing 93 (or 92), it can progress no farther. Thus, accurate positioning is assured, and this can be made to provide automatically the desired tangencies of the wires 76 with each other and with the side members 74 and 75 of the rim 71. Once inserted, the wire end 77 or 78 cannot be retracted, because on retraction, the depressed wing 92 (or 93) digs into the wire 76 and prevents outward movement. The intention is to prevent any relative movement between the wire end 77 or 78 and the member 72 or 73 after assembly. The wire 76 can move across a depressed wing 92 in the direction toward a stop wing 93 but cannot move back against the wing 92, once it has been moved in. As shown in FIGS. 7 and 10, the movement can be in either direction with the same effect exactly; it may be, of course, in opposite directions at opposite ends of the rim 71. Thus, the wires 76 are locked into the complete assembly by friction in this form of the invention. The plastic coating 79 is applied after this assembly is completed.
Friction Fastening of the Wires to the Rim (FIG. 16)
Many means of fastening the spring ends 77 and 78 to a frame member may be employed. Some of them are illustrated in the drawings in order to give some idea of the wide variations that are possible under this invention, but of course there are many others that could not be shown without the specification becoming too long.
In FIG. 16, a frame member 100 is provided with a securing member 101 which is a cylindrical segment, as seen in cross section, and has a main body portion 102 that may be welded to the frame member 100, a similar one being welded to the opposite frame member, not shown here. A series of projecting tongues 103 are provided, which may be initially made in a bent-up'position and then bent down into place as shown in FIG. 16, after the wire ends 77 or 78 have been approximately positioned so as to lock the wire ends 77 or 78 into place firmly by the members 103, clamping them between the members 103 and the frame 100. As shown in FIG. 16, this may extend along a curve, or it may extend along a straight line. Both are equally possible in the present invention, and this is a very important and unique effect of the present invention. It will be seen that with the members 101 welded on the frame members 100, installation is a relatively simple matter, involving principally flattening out and stretching the arc of the subassembly 70, anchoring one end of it first and then anchoring the other end. The plastic 79 may cover the ends 77 and 78 or may not, but installation is the same in this instance in both forms. Preferably, a plastic bearing block lies below each tongue 103. This bearing block is preferably made from plastic that is stiffer in consistency than the coating 79, and it serves as a cushion preventing the tongues 103 from abrading or cutting through the coating 79.
To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.
I claim:
1. A stacking chair, including in combination:
a. a frame having at least two spaced-apart rigid side frame portions, two front legs, two rear legs, and two spacedapart rigid back frame portions, said front legs and said rear legs being spaced apart at different distances and being operatively connected with their respective frame portions to enable compact stacking,
b. a seat assembly and a back assembly, each having a series of arcuate, continuous, sinuous wires, each having two ends, each said wire closely approaching each of its immediately adjacent said wires at frequent intervals, and a thin sleevelike stretchable plastic coating surrounding said wires, following the sinuosity of said wires and joining said wires together where they closely approach each other, said approaches being close enough for effective bridging between them by said coating, whereby said wires and plastic coating comprise a unitary assembly defining a cylindrical are,
c. first mounting means for securing said seat assembly to said rigid side frame portions across a space that flattens said arc to a flatter arc and places said seat assembly in tension along the flatter cylindrical arc, which is convex upwardly, and
d. second mounting means for securing said back assembly to said rigid back frame portions across a space that flattens said arc to a flatter arc which is convex rearwardly, each said seat assembly, when a plurality of said chairs are stacked, nesting over said seat assembly of the chair below, with part of the lower surface of each lower seat assembly lying within the chord across the seat assembly of said chair im mediately above, the back assemblies being similarly nested.
2. The stacking chair of claim 1 wherein each said assembly includes:
a rim defining a closed area of a cylindrical surface arched in one direction and straight in another direction normal to said arched direction, and having springy flexing action along said arched direction,
said series of sinuous wires each being positively anchored at opposite ends to said rim and extending across said rim in a generally circular are parallel to the arching of said rim, the longitudinal axes of said wires being parallel to each other,
said thin sleevelike plastic coating surrounding said rim, linking said wires to said rim in a unitary assembly shaped as a cylindrical arc having a curvature of less radius than that desired in said seat or back.
3. The stacking chair of claim 2 having means for mounting said rim on said frame members, and for flattening said wires somewhat to place the wires in tension along said flatter cylindrical are.
4. The stacking chair of claim 1 having mounting means for securing, separate from said coating, each said assembly to its said rigid frame portions, thereby preventing relative sliding movement of said wires therealong, said frame portions being so spaced apart that installation flattens said are to a flatter arc and places the assembly in tension.
5. The stacking chair of claim 4 wherein said mounting means comprises means for anchoring each of said wires adjacent their ends, the tension under which the wires are placed helping to retain them in place.
6. The stacking chair of claim 5 wherein each said mounting'means engages the actual wire ends to prevent movement of the two ends of each said wire toward each other.
7. The stacking chair of claim 4 wherein said wire ends lie in the same are as the remainder of their wire.
8. The stacking chair of claim 7 wherein said mounting means comprises a member having transversely outwardly extending tongues to which said wire ends are engaged, said tongues being bent down over said wires.
9. The stacking chair of claim 8 wherein said mounting means is an integral portion of said frame, said tongues being bent out portions of said frame.
10. The stacking chair of claim 1 wherein said frame is curved and said assembly is attached to the frame curve and is imparted a compound curvature.
11. The stacking chair of claim 1 wherein the wires in the seat lying closest to the forward edge of the chair are of lighter gauge than the wires of the seat in the central portion thereof, thereby imparting increased comfort.
afford the bounce dampening.

Claims (15)

1. A stacking chair, including in combination: a. a frame having at least two spaced-apart rigid side frame portions, two front legs, two rear legs, and two spaced-apart rigid back frame portions, said front legs and said rear legs being spaced apart at different distances and being operatively connected with their respective frame portions to enable compact stacking, b. a seat assembly and a back assembly, each having a series of arcuate, continuous, sinuous wires, each having two ends, each said wire closely approaching each of its immediately adjacent said wires at frequent intervals, and a thin sleevelike stretchable plastic coating surrounding said wires, following the sinuosity of said wires and joining said wires together where they closely approach each other, said approaches being close enough for effective bridging between them by said coating, whereby said wires and plastic coating comprise a unitary assembly defining a cylindrical arc, c. first mounting means for securing said seat assembly to said rigid side frame portions across a space that flattens said arc to a flatter arc and places said seat assembly in tension along the flatter cylindrical arc, which is convex upwardly, and d. second mounting means for securing said back assembly to said rigid back frame portions across a space that flattens said arc to a flatter arc which is convex rearwardly, each said seat assembly, when a plurality of said chairs are stacked, nesting over said seat assembly of the chair below, with part of the lower surface of each lower seat assembly lying within the chord across the seat assembly of said chair immediately above, the back assemblieS being similarly nested.
2. The stacking chair of claim 1 wherein each said assembly includes: a rim defining a closed area of a cylindrical surface arched in one direction and straight in another direction normal to said arched direction, and having springy flexing action along said arched direction, said series of sinuous wires each being positively anchored at opposite ends to said rim and extending across said rim in a generally circular arc parallel to the arching of said rim, the longitudinal axes of said wires being parallel to each other, said thin sleevelike plastic coating surrounding said rim, linking said wires to said rim in a unitary assembly shaped as a cylindrical arc having a curvature of less radius than that desired in said seat or back.
3. The stacking chair of claim 2 having means for mounting said rim on said frame members, and for flattening said wires somewhat to place the wires in tension along said flatter cylindrical arc.
4. The stacking chair of claim 1 having mounting means for securing, separate from said coating, each said assembly to its said rigid frame portions, thereby preventing relative sliding movement of said wires therealong, said frame portions being so spaced apart that installation flattens said arc to a flatter arc and places the assembly in tension.
5. The stacking chair of claim 4 wherein said mounting means comprises means for anchoring each of said wires adjacent their ends, the tension under which the wires are placed helping to retain them in place.
6. The stacking chair of claim 5 wherein each said mounting means engages the actual wire ends to prevent movement of the two ends of each said wire toward each other.
7. The stacking chair of claim 4 wherein said wire ends lie in the same arc as the remainder of their wire.
8. The stacking chair of claim 7 wherein said mounting means comprises a member having transversely outwardly extending tongues to which said wire ends are engaged, said tongues being bent down over said wires.
9. The stacking chair of claim 8 wherein said mounting means is an integral portion of said frame, said tongues being bent out portions of said frame.
10. The stacking chair of claim 1 wherein said frame is curved and said assembly is attached to the frame curve and is imparted a compound curvature.
11. The stacking chair of claim 1 wherein the wires in the seat lying closest to the forward edge of the chair are of lighter gauge than the wires of the seat in the central portion thereof, thereby imparting increased comfort.
12. The stacking chair of claim 1 wherein some of said wires have a different vibration frequency from other wires, in order to dampen bounce.
13. The stacking chair of claim 12 wherein some of the wires are of different thickness than others, to afford the bounce dampening to said assembly.
14. The stacking chair of claim 12 wherein some of the wires are of different configuration and arc-cycle length than others, to afford the bounce dampening.
15. The stacking chair of claim 12 wherein some of the wires are of different spring temper from others, to afford the bounce dampening.
US39526673 1972-07-03 1973-09-07 Stackable seating units Expired - Lifetime US3845986A (en)

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US00268907A US3843477A (en) 1971-03-22 1972-07-03 Arcuate wire assembly coated with plastic
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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1980002790A1 (en) * 1979-06-08 1980-12-24 D Rowland Stackable chair
US4366980A (en) * 1979-06-08 1983-01-04 Rowland David L Stackable armchair
US5587241A (en) * 1995-06-01 1996-12-24 Vaughan; Gerald L. Mineral fibers and whiskers exhibiting reduced mammalian cell toxicity, and method for their preparation
US20100301644A1 (en) * 2009-06-01 2010-12-02 Adams William E Adirondack Chair
WO2012138322A1 (en) * 2011-04-04 2012-10-11 Peters Security International, Inc. Anti-ballistic chairs
USD733449S1 (en) 2014-07-17 2015-07-07 Adams Mfg. Corp. Adirondack chair
USD968115S1 (en) * 2021-06-18 2022-11-01 Sophia & William Brands Co. Ltd Chair
USD982341S1 (en) * 2020-11-30 2023-04-04 Zhejiang Linyaco., Ltd Chair

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2731076A (en) * 1952-02-25 1956-01-17 David L Rowland Furniture seating
US2803293A (en) * 1953-10-12 1957-08-20 David L Rowland Spring assembly
US3404916A (en) * 1965-02-19 1968-10-08 David L Rowland Compactly stackable chair
US3708202A (en) * 1971-01-22 1973-01-02 American Seating Co Independent seat rise stacking and row chair

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2731076A (en) * 1952-02-25 1956-01-17 David L Rowland Furniture seating
US2803293A (en) * 1953-10-12 1957-08-20 David L Rowland Spring assembly
US3404916A (en) * 1965-02-19 1968-10-08 David L Rowland Compactly stackable chair
US3708202A (en) * 1971-01-22 1973-01-02 American Seating Co Independent seat rise stacking and row chair

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1980002790A1 (en) * 1979-06-08 1980-12-24 D Rowland Stackable chair
US4304436A (en) * 1979-06-08 1981-12-08 Rowland David L Stackable chair
US4366980A (en) * 1979-06-08 1983-01-04 Rowland David L Stackable armchair
US5587241A (en) * 1995-06-01 1996-12-24 Vaughan; Gerald L. Mineral fibers and whiskers exhibiting reduced mammalian cell toxicity, and method for their preparation
US20100301644A1 (en) * 2009-06-01 2010-12-02 Adams William E Adirondack Chair
US8333430B2 (en) * 2009-06-01 2012-12-18 Adams Mfg. Corp. Adirondack chair
WO2012138322A1 (en) * 2011-04-04 2012-10-11 Peters Security International, Inc. Anti-ballistic chairs
USD733449S1 (en) 2014-07-17 2015-07-07 Adams Mfg. Corp. Adirondack chair
USD982341S1 (en) * 2020-11-30 2023-04-04 Zhejiang Linyaco., Ltd Chair
USD968115S1 (en) * 2021-06-18 2022-11-01 Sophia & William Brands Co. Ltd Chair

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