Leggett & Platt v. Simmons Bedding et al.
`Ex. 1003 / Page 1 of 15
`
`

`
`US 7,168,117 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`2,398,237 A
`2,918,271 A
`3,985,097 A
`4,025,681 A
`4,260,143 A
`4,473,217 A
`4,753,423 A
`4,811,439 A
`4,821,390 A
`4,869,471 A
`4,889,327 A
`4,983,144 A
`4,991,827 A
`5,098,493 A
`5,137,013 A
`5,210,890 A
`5,310,167 A
`55481898 A
`5a755a022 A
`5,868,383 A
`6,220,586 B1
`6,295,891 B1
`
`4/1946 Marsack
`12/1959 Crites
`10/1976 Sitton
`......... .. 428/116
`5/1977 Donnelly etal.
`
`4/1981 Kliger ............ ..
`267/148
`9/1984 Hashimoto
`6/1988 Ukaietal.
`3/1989 Siegel
`4/1989 Seyler
`9/1989 Schwarz etal.
`12/1989 Seyler
`1/1991 OJ-ima
`2/1991 Taylor
`3/1992 Taylor
`8/1992 Chiba et a1.
`5/1993 Hagglund
`5/1994 N011, Jr.
`8/1995 N011a JP
`5/1998 S1ege1
`2/1999 Codos
`4/2001 Pavlin et al.
`10/2001 Velte et a1.
`
`6,944,899 132*
`7,047,581 132*
`2004/0158929 A1*
`2004/0158930 A1*
`2005/0005354 A1*
`
`9/2005 Gladney ...................... .. 5/716
`5/2006
`5/716
`
`8/2004 Gladney ...................... .. 5/716
`8/2004 Gladney ...................... .. 5/716
`1/2005 Gladney etal.
`............. .. 5/256
`
`FOREIGN PATENT DOCUMENTS
`
`DE
`DE
`DE
`DE
`GE
`JP
`JP
`JP
`JP
`
`300804
`815 907
`002620149 B1
`3900473
`000020583
`357069125 A
`357059125 A
`357909133 A
`58091940
`
`11/1910
`10/1951
`11/1977
`7/ 1990
`5/1911
`4/1982
`4/1982
`4/1983
`0/1983
`
`OTHER PUBLICATIONS
`The Deactivated Gun Co11ector’s Association (SIG-Sauer P225);
`Pistol P225 disclosed on http://www.remtek.com/arms/before or on
`Aug. 15, 2()()().###
`
`* cited by examiner
`
`Ex.1003/Page 2 0f15
`
`Ex. 1003 / Page 2 of 15
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`

`
`U.S. Patent
`
`Jan. 30, 2007
`
`Sheet 1 of 6
`
`US 7,168,117 B2
`
`MEAN DlA.,
`
`FREE LENGTH, Lo
`
`Figure 1, Conventional
`Compression Spring
`
`Figure 2, Stranded Wire Coil
`
`Ex.1003/Page 3 0f15
`
`Ex. 1003 / Page 3 of 15
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`

`
`U.S. Patent
`
`Jan. 30, 2007
`
`Sheet 2 of 6
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`US 7,168,117 B2
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`
`
`
`
` 35/".
`
`:15 '
`
`L L
`
`F.
`
`
`
`FIG. 3
`
`Ex.1003/Page 4 0f15
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`Ex. 1003 / Page 4 of 15
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`

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`U.S. Patent
`
`Jan. 30, 2007
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`Sheet 3 of 6
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`US 7,168,117 B2
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`FIG. 4
`
`Ex.1003/Page 5 0f15
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`Ex. 1003 / Page 5 of 15
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`

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`U.S. Patent
`
`Jan. 30, 2007
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`Sheet 4 of 6
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`US 7,168,117 B2
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`FIG. 5
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`Ex.1003/Page 6 0f15
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`Ex. 1003 / Page 6 of 15
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`

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`U.S. Patent
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`Jan. 30 2007
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`Sheet 5 of 6
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`Ex. 1003 / Page 7 of 15
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`

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`U.S. Patent
`
`Jan. 30, 2007
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`Sheet 6 of 6
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`US 7,168,117 B2
`
`Figure 8A, Uncompressed
`Stranded Wire Coil
`
`
`
`Figure 8B, Compressed Stranded
`Wire Coil
`
`Ex.1003/Page 8 0f15
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`Ex. 1003 / Page 8 of 15
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`

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`US 7,168,117 B2
`
`1
`MULTI-STRANDED COIL SPRING
`
`CROSS-REFERENCE TO RELATED PATENT
`APPLICATIONS
`
`This application is a continuation-in-part of and claims
`priority to U.S. Ser. No. 10/688,852, filed Oct. 15, 2003 now
`U.S. Pat. No. 6,944,899, which is a continuation-in-part of
`U.S. Ser. No. 10/371,177, filed Feb. 19, 2003 now U.S. Pat.
`No. 7,047,581; and also claims priority to U.S. Prov. App.
`Ser. No. 60/512,115 Oct. 17, 2003. All of the above are
`incorporated herein by reference in there entirety.
`
`FIELD OF THE INVENTION
`
`The invention relates generally to spring construction, and
`more particularly, in one embodiment, to multi stranded coil
`springs.
`
`BACKGROUND OF THE INVENTION
`
`A standard bed construction that has been popular for
`some time includes a frame for supporting a box spring. The
`box spring,
`in turn,
`is designed to support a mattress.
`Mattresses are available in a variety of sizes and are also
`constructed in various ways. One such construction that has
`proved to be highly desirable includes the use of an inner-
`spring having a plurality of discrete coil springs, which can
`be encapsulated in individual fabric pockets joined together
`in a string. An assembly of this type is commonly known as
`a Marshall construction. Once the strings of coils are
`formed, they may be arranged, for example, in a chevron or
`other pattern to provide an innerspring assembly in which
`the individual springs have longitudinal axes oriented par-
`allel one to another and the springs are closely packed
`together in an array having a generally rectangular shape in
`plan with the ends of the springs lying in a common plane.
`A suitable quilted foam pad may then be used to cover the
`innerspring and provide a generally planar surface on which
`a person can sleep. Preferably, the innerspring is covered on
`both sides and has fabric edging connecting the opposed
`surface covers, thereby defining a unitary mattress assembly.
`Conventionally, each spring is manufactured from a
`single, solid, coiled steel wire. The spring characteristic is
`defined, for example, by the wire size and spring dimensions
`(pitch, coil length, coil diameter, etc.), which can be selected
`according to the desired properties of the seating or resting
`surface of the article of fumiture or mattress in a manner
`known in the art.
`
`One disadvantage in the above described conventional
`solid wire spring construction is that steel that is suitable for
`this type of spring can be costly. Another disadvantage is
`that if one or more of the springs malfunction (e.g., break),
`the seating and/or sleeping comfort of the seating or resting
`surface is impaired. Therefore,
`it would be desirable to
`provide a spring construction that
`is less expensive to
`manufacture than a solid wire spring, and that retains or
`improves upon the performance characteristics of the solid
`wire spring.
`
`SUMMARY OF THE INVENTION
`
`The invention addresses the deficiencies in the prior art
`by, in one aspect, providing a coil spring assembly includ-
`ing, a plurality of strands configured as a multi-strand cord,
`the multi-strand cord coiled into a first helical spring having
`four or more active coils, at least one inactive coil forming
`
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`2
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`a closed end, and a free height of at least about four inches.
`Although the coil of the invention has many potential
`applications, according to one feature, it is uniquely sized
`for providing support in a resting surface, such as in a
`mattress or other article of furniture. In some constructions,
`the strands of the cord are twisted together, while in other
`constructions the strands are braided together. According to
`some embodiments, two, three or more strands are twisted
`together into the multi-strand cord. In other embodiments,
`three or more strands are braided together into the multi-
`strand cord.
`
`In one construction, the strands are formed from solid
`steel wire. However, in other constructions, the strands may
`be formed, for example, from bronze, aluminum, plastic,
`copper, titanium, rubber or any other suitable material.
`According to one configuration, the strands of the cord are
`all made from the same material. However,
`in alternate
`constructions, at least one strand is made from a different
`material than at least one other of the strands. Additionally,
`in some embodiments, the strands all have about the same
`cross-sectional diameter (i.e., gauge). However,
`in other
`embodiments, at least one of the strands has a gauge that is
`different from at
`least one other of the strands. In one
`
`preferred constructions, all of the strands of the cord have
`substantially the same cross-sectional shape. However, in
`alternate constructions, at least one of the strands has a
`cross-sectional shape different from at least one other of the
`strands.
`
`According to one preferred embodiment, the multi-strand
`cord is formed as a continuous, single segment cord. How-
`ever, in alternate embodiments, the cord includes a plurality
`of longitudinal segments, axially connected end-to-end to
`form a single cord. According to some such constructions, at
`least one of the cord segments includes one or more strands
`formed from a different material than at least one of the
`
`strands in another of the cord segments. According to other
`such constructions, at least one of the segments includes
`multiple strands and at least one of the segments is single
`stranded. In a variation of this embodiment, at least one of
`the strands of the multi-strand cord includes multiple seg-
`ments, and at least one of the strands of the multi-strand cord
`is formed as a continuous signal segment strand. In one such
`constructions, at least one of the strand segments is formed
`from a different material than at least one other of the strand
`
`segments. According to one feature, through such segment
`configurations providing differing elastic properties,
`the
`advantages of the invention can be employed to form a
`spring assembly having a variable spring rate.
`To lessen the adverse effects caused by rubbing of the
`strands against each other and wear, according to one
`configuration, one or more of the strands are coated, sealed
`or otherwise surface treated prior to being formed into the
`multi-strand cord. By way of example, the strands may be
`coated with a plastic, epoxy or PTFE (Teflon). The strands
`may also be protected by a metallurgical process, such as by
`galvanizing or anodizing. Alternatively or in combination,
`the multi-strand cord may itself be coated, sealed or other-
`wise treated, for example, with an epoxy or plastic. Accord-
`ing to one embodiment, the multi-strand cord is sleeved in,
`for example flexible plastic or rubber. In some embodiments,
`the first helical spring is substantially encased in a foam-like
`or rubber-like material subsequent to assembly.
`The strands of the multi-strand cord, in one construction,
`are joined together, for example, at one or both terminal
`ends. Additionally, or alternatively,
`the strands may be
`joined together at
`locations along its length. Fastening
`
`Ex.1003/Page 9 0f15
`
`Ex. 1003 / Page 9 of 15
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`

`
`US 7,168,117 B2
`
`3
`mechanisms, include welding, brazing, crimping, bushings
`or any other suitable joining mechanism and/or technique.
`According to one preferred embodiment, all of the coils of
`the first helical spring have substantially the same outside
`diameter. However, in other embodiments, the coil diam-
`eters may decrease in progression from one terminal end of
`the end of the spring to the other. In another embodiment, the
`coil diameters are varied to form any desired pattern, such
`as for example, decreasing in progression from a first
`terminal end of the helical spring toward a mid point in the
`spring and then increasing in diameter progressing from the
`mid point to a second terminal end of the spring.
`In a preferred embodiment, each of the active coils of the
`first helical spring have substantially the same pitch. How-
`ever, in some configurations, the pitch between first and
`second coils is different from the pitch between second and
`third coils.
`
`According to another aspect of the invention the spring
`assembly includes a second helical spring positioned con-
`centrically inside the first helical spring. According to one
`feature,
`the second helical coil can include any of the
`features of the first helical spring, including being formed
`from a multi-stranded cord. The first an second coils may be
`attached at one or both terminal ends and/or at locations
`
`along their lengths.
`the invention provides a
`According to another aspect,
`resting surface assembly, such as a mattress assembly,
`including a plurality of coil springs arranged to define a core
`structure, wherein at least a subset of the coil springs are
`multi-strand coil springs fabricated from a multi strand cord.
`In one configuration, the multi-strand coil springs are posi-
`tioned in substantially parallel alignment to each of the coil
`springs that are not part of the subset. The multi-strand coil
`springs and the coil springs that are not part of the subset are
`placed side-by-side. According to another aspect, the inven-
`tion provides, a rest surface assembly, such as a mattress
`assembly, including a plurality of coil springs arranged to
`define a core structure, wherein at least a subset of the coil
`springs includes a composite coil spring, with a first section
`of the composite coil spring being fabricated from a plurality
`of strands and a second section of the composite coil spring
`adjoining the first section in a longitudinal spring direction
`being fabricated of a single strand. Adjoining end portions of
`the first and second section are rigidly connected with each
`other.
`
`Additional embodiments may include one or more of the
`following features. The coil springs forming the core can be
`single strand coil springs or multi-strand coil springs, and
`the coil springs may have different spring rates. The coil
`springs may also have a variable, such as a non-linear and/or
`progressive, spring rate. To add support and simplify manu-
`facturing, at
`least a portion of the coil springs and the
`multi-strand coil springs can be surrounded by a foam or
`rubber-like material. Alternatively, the entire core can be
`encased in the foam or rubber-like material. The multi-
`
`strand coil springs can also be implemented as pocketed
`springs.
`Further features and advantages of the invention will be
`apparent
`from the following description of preferred
`embodiments and from the claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The following figures depict certain illustrative embodi-
`ments of the invention in which like reference numerals
`
`5
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`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`60
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`65
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`4
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`refer to like elements. In these figures, like reference des-
`ignations refer to like parts, and the various parts may not be
`drawn to scale.
`
`FIG. 1 shows schematically a conventional closed end
`coil spring.
`FIG. 2 shows schematically a multi-strand coil spring
`according to an illustrative embodiment of the invention.
`FIG. 3 shows a cross sectional view of a mattress with
`
`coils of the type depicted in FIG. 2 having ends embedded
`in a foam/rubber-like material according to an illustrative
`embodiment of the invention.
`
`FIG. 4 depicts a fragmentary perspective view of springs
`of the type depicted in FIG. 2 inserted in a slotted foan1/
`rubber support.
`FIG. 5 shows an exploded fragmentary perspective view
`of the springs and slotted foan1/rubber support of FIG. 4.
`FIG. 6 shows an exemplary composite spring made from
`two spring segments according to an illustrative embodi-
`ment of the invention.
`
`FIG. 7 depicts a coil-in-coil spring assembly made from
`multi-strand coil springs of the type depicted in FIG. 2.
`FIGS. 8A and 8B depict a multi-strand coil spring of the
`type shown in FIG. 2 flexing under force.
`
`DESCRIPTION OF ILLUSTRATIVE
`EMBODIMENTS
`
`The multi-strand coil springs described herein can be
`used, for example, to construct a wide variety of coiled
`spring applications, including seating and resting surfaces of
`articles of furniture.
`In particular,
`the multi-strand coil
`construction can be a more versatile replacement for single
`strand or solid coils in mattresses, providing enhanced utility
`and performance. For purpose of illustration,
`the coils
`described herein will be described with reference to pock-
`eted coil mattresses. However,
`the invention is not so
`limited, and may be employed with other coil spring appli-
`cations including, but not limited to, seating, flooring, weap-
`onry, writing instruments, spring hinge designs, spring lock-
`ing mechanisms, spring wound motors, specialized medical
`applications, industrial tools, spring brake devices, resilient
`shock absorption applications and the like.
`FIG. 1 illustrates the basic geometric parameters defining
`a helical compression spring. The primary spring geometric
`design parameters are: Free Length (Lo) representing the
`length of the unloaded spring; Diameter (d) representing the
`diameter of the wire or other material that is wound into the
`
`helical spring; Coil Diameter (D) representing the mean
`diameter of the helical spring,
`i.e., (Dom,+Di,me,)/2; and
`Total Number of Coils (N,) representing the number of turns
`in the helical spring. Other useful design parameters are:
`Active Coils (Na) representing the number of coils which
`deform when the spring is loaded, as opposed to the inactive
`turns at each end which are in contact with the spring seat
`or base, but do not substantially deform; Solid Length (LS)
`representing the minimum length of the spring, when the
`load is sufficiently large to close all the gaps between the
`coils; and Pitch (p) representing the distance from center to
`center of the wire in adjacent active coils. Springs in seating
`and resting surfaces of articles of furniture typically employ
`closed end springs of the type illustrated in FIG. 1. Closed
`end springs typically have at most one inactive coil at each
`end of the spring.
`The selection of the spring material is usually the first step
`in parametric spring design. Material selection may be based
`on a number of factors, including temperature range, tensile
`strength, elastic modulus, fatigue life, corrosion resistance,
`
`Ex. 1003/Page 10 0f15
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`Ex. 1003 / Page 10 of 15
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`US 7,168,117 B2
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`5
`cost, etc. High-carbon spring steels are the most commonly
`used of all springs materials. They are relatively inexpen-
`sive, readily available, and easily worked. Examples include
`Music (ASTM A228) wire and Hard Drawn (ASTM A227)
`wire, which are suitable for springs used, for example, in
`mattresses. Spring wires can be surface-treated, such as by
`being galvanized or coated with a plastic or epoxy.
`Spring wire used in mattress coil spring construction
`typically has a diameter of between about 0.06" (16 gauge)
`and about 0.09" (13 gauge), with each coil spring made of
`a single strand of spring wire. The exact design parameters
`for mattress coil springs depend, for example, on the desired
`fimmess, which is in addition determined by the number of
`springs per unit surface area of the mattress. Both single
`strand and, according to the invention, multi-strand coils can
`be designed to have a variable spring rate, meaning that the
`spring excursion varies non-linearly with the applied load.
`FIG. 2 shows schematically a multi-strand coil spring 20
`according to an illustrative embodiment of the invention.
`The coil spring 20 employs a multi-strand cord 22, which is
`bent to form the coil spring 20. Preferably, at least two
`strands are twisted to form the multi-strand cord 22. How-
`
`ever, the number of strands employed varies according to the
`application and the type of material used to form the strands.
`In some constructions, the cord 22 is formed from braiding
`three or more strands. In one preferred construction, the
`multi-strand cord 22 includes from three to about fifty
`braided strands. As described below, testing by applicants
`has shown that coil springs formed from multi-strand cords,
`braided or twisted, have improved performance character-
`istics over conventional single strand spring.
`The illustrative coil spring 20 is closed ended and formed
`from three strands. It has an outside diameter 22 of about 2"
`
`and an N,:6 coils, with one coil 24 being an inactive coil, as
`defined above. An exemplary free length L0 26 is between
`about 5" and about 6". The spring 20 can be made, for
`example, of carbon steel, such as ASTM A227/A228, with
`each strand having an outside diameter of about 0.514" (1.3
`mm), which is equivalent to a about 171/2 gauge. With these
`parameters, the spring rate is about 1.4 1b., which gives the
`following characteristic:
`
`Approximate Working
`Deflection (inches)
`0.75
`1.0
`2.5
`3.0
`
`Approximate Working Load
`(lbf)
`1.07
`1.43
`3.57
`4.28
`
`The fatigue performance of the illustrated multi-strand
`spring design is estimated to be between about 100,000 and
`about 1,000,000 operation cycles at about 2.75" deflection,
`which corresponds to a useful life of about 15 years. The
`efficiency and performance of the spring is understood to
`increase with the number of strands. However, the cost also
`tends to increase with the number of strands. Applicants
`estimate that the spring will suffer no more than about 5%
`relaxation over 15 years when deflected by about 2.75".
`A significant advantage of the invention is that multi-
`strand springs are essentially fault tolerant
`in that
`they
`remain functional even when one or more of the strands
`
`break. The strands may be twisted, woven, clipped or
`bonded together, and any suitable method for forming the
`multi-strand coil spring may be employed without departing
`from the scope of the invention. The strands may be formed,
`
`6
`for example, from steel, aluminum, plastic, copper, titanium,
`rubber or any other suitable material, with the type of
`material selected depending on the application at hand.
`Morever, the strands may have an ovular, circular, hexago-
`nal, square, flattened version of any of the preceding or any
`other suitable cross-sectional geometry, and may be formed
`into any number of coils. Additionally, the strand gauge may
`vary according to the application, and in one embodiment is
`about 710 gauge, although other gauges may be used. Also,
`the coils themselves may be formed as active or inactive
`coils, and may all have substantially equal Coil Diameters
`(D). Alternatively, the Coil Diameter (D) may vary from coil
`to coil, and may be arranged, for example to have sequen-
`tially increasing Coil Diameters (D), Sequentially decreas-
`ing Coil Diameters, or some combination of both, to form
`any suitable coil diameter pattern, for example, for forming
`a coil spring having a variable spring rate. Other ways to
`form coils having a variable spring rate are discussed below
`with respect to FIG. 6.
`Additionally, although the coils are depicted as being
`substantially circular in geometry, they may be oval, hex-
`agonal, rectangular, square or any other suitable geometry.
`Further, although the Pitch (P) is depicted in FIG. 2 as being
`substantially constant from active coil to active coil, this
`need not be the case and the pitch may vary from active coil
`to active coil.
`
`The exemplary multi-strand coil spring 20 can be fabri-
`cated by initially providing the individual strands with a
`helical twist prior to the cording operation. The helix of the
`multi-strand spring preferably opposes the helix of the
`individual strands to counteract a tendency of the strands to
`loosen when the spring is operated, i.e., compressed. Addi-
`tionally, as with conventional springs, a torque is applied to
`the cord during coiling.
`In one practice, coiling may be achieved by passing a
`braided cord through a coiler, such as the type of coiler
`employed for forming steel mattress coils, wherein a heavy-
`gauge steel wire is compressed into a barrel-shaped coil such
`that no turns touch for eliminating noise and vibration. The
`coils may then be passed to a pocketing machine or station
`to pocket the springs into individual sleeves of a non-woven,
`non-allergenic fabric such as Duon. Each sleeve is ultra-
`sonically sealed by a process where the fibers are melted
`together to form solid plastic seams, which are secure and
`tear-resistant. The coils are then fusion bonded to produce a
`strong, stable construction. The number of coils in each unit
`may vary, and the types of coils and the number of strands
`and gauge of strands can vary from pocket to pocket, and
`multi-strand coils may be employed in combination with
`single strand coils.
`The individual strands are connected to each other at least
`
`at the ends of the coil. Since the strands can rub against each
`other over the length of the coil, which can cause fretting and
`premature wear,
`the strands may be coated and/or pre-
`galvanized or otherwise treated. Moreover, the multi-strand
`coil may also be sealed/coated with a sealant, such as an
`epoxy.
`the various strands of the
`According to one feature,
`multi-strand coil spring 20 may be made of differing mate-
`rials, for example, different types of metals, such as bronze,
`titanium and the like, as well as various types of spring steels
`having different elastic properties. In this way, the elasticity
`of the spring, or the spring rate, can be tailored to specific
`applications, without the need to acquire or stock a large
`quantity of conventional dissimilar coil wires. Other elastic
`materials having spring-like properties, for example suitable
`plastics, may also be used.
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`Ex. 1003 / Page 11 of 15
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`

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`US 7,168,117 B2
`
`7
`To lessen the risk of the strands fretting, the strands can
`be selectively welded at predetermined locations along the
`length of the multi-strand cord, either when the multi-strand
`cord is fabricated or when the coil is being formed. The coil
`can thereafter be coated or galvanized along the multi-strand
`cord, or the entire coil may be encased in a foam-like or
`rubber-like material, which can be poured or wrapped
`around the coil strands. Alternatively or in addition, a coil
`can be completely surrounded by a “block” of foam-like or
`rubber-like material, or the entire mattress core may be filled
`with foam. This can add lateral stability to the multi-strand
`coil springs and/or, if the foam is impervious to air, can
`protect the coil springs from environmental effects.
`FIG. 3 depicts a section of a mattress 20 constructed with
`multi-strand wire coils 26 whereby additional support is
`provided by encasing at least the end sections of the springs
`in the foam 22, 24. Other resilient materials, such as rubber
`and/or latex, can also be used. This arrangement obviates the
`need for connecting the ends of the springs individually to
`a frame or to each other and can furthermore provide a
`sleeping surface adapted for the comfort of a user. According
`to one feature, the illustrative construction advantageously
`provides additional lateral support for the multi-strand coils.
`Turning now to FIGS. 4 and 5, support for the multi-strand
`coil springs and the mattress construction in general may
`also be improved by placing foam 30 between or around the
`coil springs 34, for example, by slitting the foam 30 sub-
`stantially parallel (32a, 32b, 32c) to the spring turns (see
`FIG. 5) and pressing the foam into the sides of the coil
`spring. This approach makes it possible to reduce the
`number of springs in a mattress, thereby reducing also the
`weight and the manufacturing costs of the mattress. The
`resiliency of the mattress which is related to the desired
`sleeping comfort of a user, can be further tailored to the
`user’s needs by completely encasing the multi-strand coil
`springs in foam. A foam with sealed pores can furthermore
`protect the multi-strand coil spring from corrosion, which is
`even more important for multi-strand coil springs than for
`solid wire springs due to the larger surface-to-volume ratio
`of the multi-strand coil springs and potentially developing
`weak spot on the spring surface caused by fretting, as
`described above.
`
`Multi-strand coil springs that are enclosed/encased in
`foam need not be arranged in a regular pattern and springs
`with different spring rates can be easily incorporated. In this
`way, a mattress having a different softness in different areas
`of the sleeping surface can be easily constructed by placing
`springs with different spring rates in any desired pattern.
`Since the foarn-encased springs, preferably, do not need
`additional mechanical reinforcement
`(in addition to the
`foam) and do not have to be interconnected, for example, by
`hog rings or tie wires, the mattress design can be imple-
`mented easily, and quickly changed, without additional
`tooling, which also reduces manufacturing costs.
`As also seen in FIGS. 3 and 5, other types of spring
`elements 39, such as vertical springs, can also be fabricated
`from a multi-strand cord and additionally supported by or
`encased in foam 30. The orientation of the slits can be
`
`arranged so as to match the orientation of the individual
`sections 33, 35 of the spring elements. Moreover, adjacent
`springs 34 and/or spring elements 39 can be connected in an
`alternating arrangement, whereby a top section of a spring
`element 39 is connected to the top section of an adjacent
`spring element 39 by cross-wire 38, with the bottom section
`of a top-connected spring element 39 then connected to a
`bottom section of the next spring element 39 (not shown),
`and so on. In this way, a succession of springs can be
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`manufactured from a continuous wire (either solid or
`braided/stranded) without separating the individual springs.
`Moreover, FIG. 5 illustrates that the multi-strand springs
`34 may be arranged in a row that extends along at least a
`portion of the length of the mattress. In one practice, the
`multi-strand springs 34 are arranged as an edge support
`disposed at the peripheral edge of the mattress and capable
`of providing a more robust and firm edge for the mattress.
`To this end, the multi-strand springs may have a spring
`constant that is greater than the spring constant of other
`springs employed within the mattress. The firnmess of the
`multi-strand springs 34 may be selected for the intended
`purpose of providing greater support, and in particular,
`sufficient support to allow a person to sit comfortably on the
`edge of the mattress, without the mattress edge collapsing
`under the person’s weight. The edge support may be pro-
`vided to the lateral edges of the mattress or may be applied
`around the full periphery of the mattress.
`FIG. 6 illustrates an exemplary embodiment of a spring
`60, which can have a variable spring rate. The multi-strand
`wire coils of the invention can be employed in the design of
`such a spring. A spring 60 with a variable spring rate can
`provide a mattress
`sleeping surface that has a “soft”
`response if less pressure exerted by a user (i.e. if the weight
`of the user is relatively low), with the response becoming
`“harder” for heavier users. A first section 62 of the spring 60
`may be manufactured, for example, from a solid coil wire
`having a first, typically lower spring rate (stilfer spring). A
`second section 64 may be implemented, for example, as a
`multi-strand coil wire and attached to an end of the section
`
`62, for example, by crimping a sleeve 66 over the adjoining
`end portions of each section 62, 64. The sleeve 66 can be
`made of metal or a sturdy plastic that can withstand the
`applied torsion and other forces. Other means for connecting
`the sections 62 and 64, with or without a sleeve 66, may
`include, for example, welding or brazing.
`One desirable quality of multi-strand coil springs is that
`for the same cord diameter and same cord material, multi-
`strand coil springs have a greater spring rate than single
`strand coil springs. As a consequence, employing the multi-
`strand springs of the invention, the spring 60 can be con-
`figured such that the multi-strand section 64 compresses
`under a first load, giving the “soft” response, and the single
`strand section 62 thereafter compresses under an increased
`load relative to the first load to provide the “harder” response
`relative to the section 64. The response can be further
`adjusted, for example, by inserting foam (30; see FIGS. 4
`and 5), as described above.
`In another exemplary embodiment depicted in FIG. 7, a
`multi-strand coil 72 is inserted into and/or afi‘ixed inside
`
`another (multi-strand wire) coil spring 74 of a larger diam-
`eter to create a combined spring 70. By selecting the above
`described spring parameters of the inner 72 and outer 74
`springs, the combined spring 70 can be configured to have
`a desired constant or variable spring rate, thus providing
`similar advantages to the hybrid spring 60 of FIG. 6. Either
`or both coil springs 72 and 74 can be made from a multi-
`strand cord, braided cord or single strand, or can have the
`split coil configuration depicted in FIG. 6. According to one
`feature, a mattress core or other resting surface of an article
`of furniture may be manufactured by first arranging outer
`coil springs in a desired pattern and then selectively placing
`multi-strand wire coils inside the outer coil springs. The
`inner coils can be secured to the outer coils in a conventional
`
`manner, for example, with hog rings, wire, straps, etc. The
`manufacture may be particularly simplified by using the
`foam construction depicted in FIGS. 3—5, in which case the
`
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`Ex. 1003 / Page 12 of 15
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`US 7,168,117 B2
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`9
`inner coil springs may simply be placed inside the outer
`springs without additional mechanical attachment to the
`outer coil spring, before the foam is applied.
`FIGS. 8A and 8B show the exemplary multi-strand coil
`spring illustrated in FIG. 2 during flexing. Testing results
`demonstrate that a three cord multi-strand coil spring having
`strands of steel with an average gauge will withstand about
`4.4 million coil flexes from a height of about 9% inches
`(FIG. 8A) to a height of about 11/2 inches (FIG. 8B) without
`separation. The coil spring is formed utilizing a commercial
`coiler machine and the steel strands have no bands or
`
`coating. Multi-strand coil springs of the type utilized possess
`adequate performance characteristics for a wide variety of
`coiled spring applications and may be tailored to specifically
`perform even more applications. Such applications include
`furniture uses, particularly rest surfaces, such as matt