US2834403A

US2834403A - Strip spring construction

Info

Publication number: US2834403A
Application number: US637456A
Authority: US
Inventors: Pitts Kennard; Elmer A Herider
Original assignee: Rockwell Spring and Axle Co
Current assignee: Rockwell Spring and Axle Co
Priority date: 1957-01-31
Filing date: 1957-01-31
Publication date: 1958-05-13
Anticipated expiration: 1975-05-13

Description

May 13, 1958 Filed Jan. 31, 1957 K. PITTS ET AL.

STRIP SPRING CONSTRUCTION 2 Sheets-Sheet 1 8 4 F/ I l r,- 56 38 in i 42 I I I I ,PM -40 I i 38 I b oisgji: i a I I I ll ltl I l I JIM l 5s I l i f m HIM M E i: I o i: "-38 i l 5 p a: H I

Fig.2

INVENTORS.

Ken/lard Pitts Elmer A. Her o'er THE IR A TTORNE Y5 y 1958 K. PlTTS ET AL 2,834,403

STRIP SPRING CONSTRUCTION Filed Jan. 31, 1957 2 Sheets-Sheet 2 so 10 T4 bill!!!" INVENTORS. K'ehnard Pitts Elmer A. Herider HE /R ATTORNE Y5 United States Patent 9 STRIP SPRING CONSTRUCTION Kennard Pitts, Detroit, and Elmer A. Herider, Dearborn Township, Wayne County, Mich., assignors to Rockwell Spring and Axle C0., Coraopolis, Pa., :1 corporation of Pennsylvania Application January 31, 1957, Serial No. 637,456

6 Claims. (Cl. 155-179) This invention relates to strip spring constructions and cushion assemblies made therefrom, and more particularly, to a one-piece spring'element formed from a length of steel strip spring stock and being directly securable to a frame.

The strip spring stock is cut to length according to one embodiment of the spring element hereof and is bent at acute angles at two points to provide a supported straight center section for engaging the load and a pair of supporting sections at the opposite ends thereof for supporting the loaded. center section. The noted embodiment is primarily adapted for back rest cushions whereas another embodiment herein disclosed constitutes a seat cushion element which is bent at three points and rebent at one of those points to provide a load engaging center portion supported at one end by a portion forming an oval with that end of the center portion and an offset attaching terminal extending from an opposite side of the center portion at the opposite end thereof. In both embodiments the attachment of the supporting portions of the spring to a spring cushion frame is such that each portionnmay be quickly caught on a locator pin or grommet and effectively secured at this one point only, to the frameand' in a novel manner thereafter preventing a loose joint or dislodgement at that joint. In each embodiment the attaching points are closely spaced in a comparative sense to the available spring span, requiring the spring to be foreshortened between the ends thereby arching the center portion outwardly under prestress to provide a desired contour with its resulting comfort. The actual pin or grommet connection provides convenient locators for the spring and the supporting portions of the latter are pierced with openings which readily catch upon the pin iocators when they come into registry there: with.

Further features, objects and advantages willeither be specifically pointed out or become apparent when for a better understanding of the invention reference is made to the following description taken in conjunction with the accompanying drawings which show a preferred em bodiment hereof and in which:

Figure 1 is a broken elevational view of a seat assembly arranged with seat and back rest cushions embodying the present invention;

Figure 2 is a broken plan view of the seat cushion of Figure 1;

Figure 3 is a perspective View of the seat cushion strip element after being bent to form;

Figure 4 is a perspectiveview of the element illustrated in Figure 3 after one end is turned under and attached to the load engaging spring element; and- Figures 5 and 6 are sequential views in enlarged cross section showing the attachment portion of one of the spring elements being secured to a frame member.

In particular reference to Figure 1 of the drawings, a seat cushion frame 10 of generally rectangular construction is illustrated which is principally intended for vehicle seating assemblies, primarily the front seat of the .JCC

vehicle. It will be understood that the relatively shallow cushion hereinafter described provided on this frame adapts it adequately for use as the seat cushion in a rear seat and with minor modification for use as a seat back rest. A standard 12 rigid at the bottom with the rear of the seat frame 10 carries a back rest mounting racket 14 at its upper end. A folding type back rest frame includes upper and lower cross members rigid with a vertical pair of spaced frame members 20 and 22 which at their lower ends pivot on a hinge pin 24 carried by the mounting bracket 14 to fold the back rest downa wardly in conventional way. The pair of vertical frame members 20 and 22 carries a back rest cushion 26 forming one of the split halves of a split type back rest which is only partially shown. The cushion 26 typifies each half of the back rest, however, and in one physically constructed embodiment of the invention, incorporate-d seven bands forming the row of strip

spring cushion elements

28, 30, etc., and each being generally 2" in width and made from 0.025" thick blue temperedsteel strip spring stock. The element 28 which is typical of the elements in that row includes a supported portion 32. covered with the usual foam rubber padding and upholstery cloth to support the load of a seat occupants back and having a pair of bends 34 formed at its opposite ends to provide supporting portions 36 which are punched and secured by rivet connections 38 at their terminals to the respective upper and lower cross mem:

bers

16 and 18 in the back rest frame. While in manufacture the strip element 28 may be arched to a desirable degree, the spring herein illustrated is retained in flat strip form and is thereafter bent only at the two bends 34 providing a straight center section which forms the supported portion 32 and the opposite end sections around the bends being substantially straight and disposed in acute angular relationship to thestraight center section. When the end sections are drawn together into a fore, shortened position to be secured to the-rivet connections 38, they arch the supported portion 32 of each element outwardly and stress all portions into a continuous arouate shape.

In Figures 1 and 2, the seat cushion frame 10 includes front and

rear cross members

40,42; which are joined together at their midportions if desired, but which in any case rest at their outer ends upon and are securely joined to a pair of spaced side rail members 44 in the frame, The

cross members

40 and 42 mutually carry a row46 of seat cushion spring elements which in one physically constructed embodiment. of the invention were fifteen in number constituted by one-piece bands which were gen erally 2" in width and made from 0.025 thick blue tent; pered steel strip spring stock. Each of the spring ele; ments in the row 46 includesa supported portion 48 adapted to be covered with the usual foam rubber and upholstery cloth to form a full width seat-cushion 50 and having first and second

main bends

52 and 54 lengthwise thereof at one end enabling the band to loop on itselfand carry a rivet 56 at theupper portion to form a closed oval 58. The upper structure of the closed oval. 58, therefore, constitutes a supporting portion at the inter mediate location of the rivet 56 between the ends, of the supported portion 48 and at-a lower. point the oval has rivet connections 38 of the character already noted which with similar connections is disposed in a row for securing the cushion elements at spaced'points to the front cross member 40. A single rivet connection38, is usually suflicient for securing one spring element to the member 40 although two connections 38 may be provided according to Figure 2 for each of the elements. seen at the end ofthe row 46. l

At the opposite end of the spring element, the supported portion 48 is crimped to form an upwardly offset attachment terminal 60 which lies fiat against the sloping upper wall of the cross member 42 and is secured thereto by means of another of the rivet connections 38 already noted. The rivet connections on the rear cross member 42 are disposed in a row at spaced points therealong and one such connection is sufiicient for each element in the row of strips 46 although two may be provided for the end elements as indicated in Figure 2.

The construction of the seat cushion elements from a one-piece band of spring strip stock is illustrated in Figures 3 and 4. While the band during manufacture may be arched to a desirable degree, the seat cushion spring element herein illustrated is retained in fiat form and is thereafter bent to form in a general P-shape by being crimped adjacent the straight section at one end forming the attachment terminal 60 and by being bent at the opposite end so that adjacent the first main bend 52 it has a straight section extending at an acute angle and from which a straight extremity section 62 extends at a slightly oblique angle around the second main bend 54. The extending section has a fastener opening 64 punched therein midway of the

bends

52, 54 and its straight extremity section 62 is punched with a fastener opening 66 adjacent the terminal. The straight center section of the element which forms the supported portion 48 is punched with another fastener opening 68 substantially transversely aligned with the fastener opening 64 therebelow and the attaching terminal 60 is formed with another fastener opening 70, all of which openings are preferably made by a punching operation prior to the bending and crimping operations. The crimping operation results in an S-shaped construction adjacent the attachment terminal 60 providing a deep bend 72 with a relatively long angular are which is sufficient to give the required upward offset to the attachment terminal 60 and further providing a rebend 74 immediately contiguous to the deep bend for directing the terminal 60 to lie flat against the sloping wall of the associated transversely extending cross member 42.

The terminal of the extremity section 62 is turned under in the manner of a spiral from its backwardly extending relaxed condition of Figure 3 and forced into tangentially overlapping relationship with the supported portion 48 whereupon the rivet 56 is fastened in the registering

fastener openings

66 and 68. The forward part of the supported portion 48 thus arches outwardly stressing the closed oval 58 into a continuously arcuate shape.

In Figures 5 and 6, the present rivet connections 38 are so made to avoid the need for providing actual separate rivet elements. The specific connection between the attachment terminal 60 of the strip element and the frame member 42 is illustrated as typical of the connections 38 used for attaching the various cushion element portions to their associated cushion frame members. The

frame members

40 and 42 are metal, preferably steel, and a hollow grommet 76 is pierced and extruded outwardly of the frame member for a short length. This length is preferably suflicient to produce an upstanding guide pin effect for piloting the fastener opening 70 as it is brought into a confronting position where it catches over and settles downwardly upon the grommet 76. These grommets 76 in one design of the invention were in rows on the

various frame members

16, 18, 40, and 42 and spaced approximately 3 /2 on center. The ends of the supported portion 48 of the seat cushion element must be slightly foreshortened in order for the opening 76 to catch onto the grommet 76 and accordingly the supported portion 48 assumes the dotted line arched position shown by the dotted lines 48a in Figure 5. Thereafter a spinning tool, not shown, is brought up to the mouth of the hollow grommet 76 at its outer end and is rotated under power in a conventional way thereby expanding the mouth of the opening and securely spinning down the metal of the grommet 76 about the mouth of the fastener opening 70. Inasmuch as there are no fasteners to handle or to sepa- 4 rately support in the fastener openings, the assembler finds it an easy matter with one hand to steady the spring element on the grommet which thus provides a solid locator therefor and he then has the other hand free to handle and operate the spinning tool, not shown.

The foregoing

strip spring elements

28, 30, etc., in one row in the back rest and the seat cushion elements in the other row 46 provide a desired contour for the cushions 26 and S0. The back rest springs 28 and 30 lend themselves to various adjustments for changing the contour and for changing the support which they apply to a load by changes of the preformed angularity in the bends 34. By changing the gauge of the steel strip stock thickness, the degree of hardness or softness of these elements may be further controlled. The seat cushion elements in the row 46 lend themselves to various adjustments for changing the contour and the rate of deflection by changing the radii of the S-shaped bends and rebends 72 and 74 which are crimped together and also by changing their depth. Through changing the angular relationships of the bends and their radii at 52 and 54 in Figure 3, further changes in contour and rate of deflection are obtained. It is highly important that the

cross members

16 and 18 and the

cross members

40 and 42, respectively, be sufiiciently closely spaced that the transverse supporting surfaces which they present fall short of the attachment portions of the extended lengths of the spring elements. Thus the supported portions of the spring elements must be efiectively shortened to locate them on the grommets for securing them to the cross members thereby arching the supported portion outwardly to the desired contour.

Variations within the spirit and scope of the invention described are equally comprehended by the foregoing description.

We claim:

1. In combination, a spring element made from a onepiece spring metal band having a supported portion and a pair of portions at the ends projecting outwardly from opposite sides, one of which projecting portions extends at an acute angle from the supported portion and from which a section is bent and overlapped in a joint to the supported portion between its ends thereby arching a section of said supported portion and stressing said extending portion into complementary arched shape, the other projecting portion of said pair having a substantially straight terminal joined to said supported portion by a main bend to produce an upward offset between the two portions and further joined by a rebend for directing the terminal of the projecting portion for lying flat against a transverse supporting surface, and spaced transverse frame members presenting integral spring securing means on which to pin respectively said upwardly offset terminal and said extending portion at a point in the lower arch thereof opposite to the overlapped joint.

2. For use in cushion constructions, a one-piece spring element made of a length of spring metal band having a supported portion and a pair of portions at the ends projecting outwardly from oposite sides, one of which projecting portions of said pair extends at an acute angle from the supported portion and from which a section is bent and overlapped in a joint to the supported portion between its ends thereby arching a section of said supported portion and stressing said extending portion into an arcuate shape, the other projecting portion of said pair having a substantially straight terminal joined to said supported portion by a main bend to produce an upward offset between the two portions and further joined by a rebend for directing the terminal of the projecting portion for lying flat against a transverse supporting surface, and openings for mounting-fasteners formed in said upwardly offset terminal and in said extending portion at a point in the lower arch opposite to the overlapped joint.

3. In combination, a strip spring element made from a one-piece spring steel band bent lengthwise at longitudinally spaced points into a generally P-shape in relaxed state, each of the sections of the spring element joined by the bends being substantially straight and containing a fastener opening punched;' through that straight section of the band, means lodged in the appropriate associated fastener openings to rivet an end section of the strip element to another section thereof in tangentially overlapped relationship to form a closed figure therewith stressed into an entirely arcuate, oval shape, a metal frame to support the spring element including a transverse supporting member below the opposite straight end section thereof, and spring securing means including an upset grommet portion extruded from the metal of said transverse frame member to project through the fastener opening in the last named straight end section and having the grommet metal spun over around the mouth of said opening.

4. In combination with a plurality of spring cushion elements, a transverse support member of metal, said cushion elements each having a supported portion and supporting portions therefor including one portion extending at an angle from one end thereof from which a section is bent and tangentially overlapped in a joint to the supported portion between its ends thereby stressing said extending portion into a continuously arcuate shape, said supportingportions having fastener openings therein, and spring securing means comprising a row of spaced grommets adapted for spinning and being extruded outwardly from the metal of said member to enter the fastener openings as locators when the supporting portions of said spring elements catch thereupon for support.

5. A spring cushion construction for seats including a spring element made from a one-piece spring metal band having a supported portion and a pair of portions at the ends projecting outwardly from opposite sides, one of which projecting portions extending straight from the supported portion in acute angular relationship thereto, the end of said straight extending portion being bent backward under the supported portion to form an angle with said straight extending portion, a rivet for securing the end of said last bent portion to the supported portion medially of its ends and arching the included end of the supported portion therewith into an oval shape, the other projecting portion of said pair having an attachment terminal joined to said supported portion by a main bend to produce an upward offset between the two portions and further joined by a rebend for directing the attachment terminal flatly against a transverse supporting surface, and spaced transverse frame members presenting integral spring securing means on which to pin said spring element at points respectively on said upwardly offset attachment terminal and on said extending portion.

6. A spring cushion construction for seats including a plurality of spring elements each made from a one-piece spring metal band and having a supported portion and a pair of portions at the ends projecting outwardly from the opposite sides, one of which projecting portions extending straight from the supported portion in acute angular relationship thereto, the end of said straight extending portion being bent backward under the supported portion to form an angle with said straight extending portion, a rivet for securing the end of said last bent portion to the supported portion medially of its ends and arching the included end of the supported portion therewith into an oval shape, the other projecting portion of said pair having an attachment terminal joined to said supported portion by a main bend to produce an upward offset between the two portions and further joined by a rebend for directing the attachment terminal flatly against a transverse supporting surface, and spaced transverse frame members presenting integral spring securing means extruded outwardly from the metal thereof and spun over within fastener openings respectively provided in said upwardly offset attachment terminals :and said extending portions of said spring elements.

References vCited in the file of this patent UNITED STATES PATENTS 132,350 Briggs Oct. 22, 1872 FOREIGN PATENTS 330,729 France -Q. July 7, 1903 667,407 France June 17, 1929