FIELD OF THE INVENTION

The invention relates to spring components for cushioning devices, cushioning devices comprising such spring components, and methods of manufacturing both the spring components and the cushioning devices comprising them.

BACKGROUND

Firm, unyielding furniture is discomforting to sit or lie upon for extended periods of time. A time-honoured solution to this problem has been to provide mattresses, cushions, or similar cushioning devices comprising springs, so that beds, chairs, sofas and the like can offer a surface which supports the body whilst yielding more than solid, inelastic bodies.

Mattress springs are usually traditional coil springs, often made of metal or other hard materials. There are numerous problems that arise from this. Metal prices have increased substantially, metal springs can make unappealing creaking sounds, if a mattress is damaged or becomes worn then protruding springs may pose a danger, and so on. In addition, metal springs are not suitable for other applications such as in pillows.

In recent years foam materials have become prominent alternatives to the use of metal springs; such foams are soft, cost-effective, and can be used in applications ranging from head pillows to bed mattresses. It is possible to produce a cushioning device simply by providing a block of foam, but this is often not ideal; the resulting component will usually have similar support properties across its entire area, which may not be what is desired, and customers used to mattresses having defined springs may feel put off by a mattress which is simply a solid mass.

One solution to this problem is to provide individual foam springs which can be used in the assembly of foam-based mattresses and other cushioning devices. This has the advantage of both familiarity and customisability; different springs with different properties can be used to provide a varying level of support across a mattress or other cushioning device, making the resultant cushioning device more yielding or more firm in different areas as desired. However, this approach has its own problems, since the individual foam springs must be individually fixed in place; this makes manufacture of cushioning devices substantially more complex, and therefore more costly and time-consuming. There is therefore a long-felt need for a means of providing foam springs for cushioning devices which reduces the complexity, time requirement, and cost of manufacturing cushioning devices comprising such springs. It would be preferable if springs could be provided both for standard non-customised cushioning devices in which the springs all have broadly the same cushioning properties, as well as in customised cushioning devices, in which springs with differing cushioning properties are placed in different zones of the cushioning device in order to tailor the level of cushioning performance across the device.

PRIOR ART

Document WO2007128113 [RANCOURT] discloses a grid of individual foam blocks each provided with an internal cavity and maintained together by transverse web elements equal in breadth to and interconnecting adjacent foam blocks. Individual blocks and their cavities may be formed from a single large foam block using machine techniques, starting with a single large foam block.

Document US6637053 [DINAPOLI] discloses a grid of parallel foam members separated by tranvserse bonded foam blocks the foam members being joined by elongate slats which are bonded into transverse block slots and held in place on each foam member by elongate webs which are bonded to the surface of each foam member. The document is silent as to the method of manufacture of the foam members. Document DE19521910 [WOESTE] discloses a centre layer having a grid of upwardly and downwardly projecting conical foam protusions 2 each having a blind axial bore 4; thorugh air ventilation channels 3 are provided between the protrusions with lip valves 5 in the channels 3. The document is silent as to the method of manufacture of the protrusions.

Document CN101375761 [A RONG] discloses a latex bed mattress with adjustable local hardness comprises an elastic mesh and a plurality of latex column units, wherein the latex column units are respectively arranged in each grid of the mesh; the column units are shown individual with grooves to cooperste with a mesh and to have axial apertures. The English abstract is silent as to the method of manufacture of the protrusions.

Document GB476659 [US RUBBER] discloses circular sponge rubber tubular elements preferably joined together at their contacting surfaces by cement or in other desired manner so as to form a unit assembly; which assembly is shown to have a grid-like structure wherein the tubular elements are joined together at their meeting surfaces.. The document is silent as to the method of manufacture of the tubular elements.

Document US4603445 [SPANN] discloses a foam pad for use as a mattress cover and the like, having a plurality of upstanding projections or promontories formed integrally from a flat synthetic foam blank The projections are disposed in patterns such as aligned rows and a void, preferrably slightly larger than the projections, is provided on each side of the projections forming valleys and the free standing projecting portions. Connecting foam portions integrally join corners of the projections to corners of adjacent blocks in a next row. The connecting foam portions extend upwardly from the base and terminate short of said planar apex surfaces permitting independent movement of the projections as well as free movement of air. The blocks are formed by a punch and die or a convoluter.

Document US20110126356 [METZELER] discloses a cylindrical spring element consisting exclusively of an elastic open-cell flexible polyurethane foam and is produced by molded foaming. Provided in the middle of the spring element is a recess extending axially, produced by a corresponding configuration of the foaming mold. A preferred embodiment of a spring element unit comprising a total of four spring elements 10 arranged inline and materially positively connected in the region of their facing jointing face by means of an adhesively bonded connection.

Document US6347424 [STUMPF] discloses a connected series or string of jacketed cushion elements comprising individual plug-like cylindrical bodies of resiliently compressible material embraced along their curved surfaces by a pair of strips of sheet material joined together on diametrically opposite sides of the cylindrical bodies. The elements may be die- cut or trepanned from a slab of foam of the desired thickness, but are preferably either molded individually in cylindrical form and trimmed to desired height, or continuously extruded and cut to length.

STATEMENT OF THE INVENTION

A spring component for a cushioning device, a cushioning device, a method of manufacturing a spring component for a cushioning device, and method of manufacturing a mattress according to the present invention and embodiments thereof are defined by the appended claims. SUMMARY OF THE INVENTION

Accordingly, the present invention provides a spring component for a cushioning device comprising a chain of foam spring elements. The spring component is cut from a foam body and each spring element comprises a top surface and a base surface with at least one side surface there between; the spring elements are of uniform cross-section, without bores or the like apertures. Integral longitudinally and axially extending links connect the side surfaces of neighbouring spring elements and the links have a transverse dimension narrower than that of the spring elements. There are also provided links between neighbouring spring elements. These links may be regarded in some embodiments as pivots. Unlike the above-referred prior art documents, spring components in accordance with the present invention benefit from one of more of the following features: spring components cut from a foam body, spring elements connected by integral links, spring elements of uniform cross-section, without bores or the like apertures, the links having a transverse dimension narrower than that of the spring elements.

Shaping the spring components by cutting is a flexible inexpensive manufacturing process readily permitting changes in the design and shape of the spring elements.

The designed shape of the spring elements enables cushioning devices to perform at least as well as those of the above-referred prior art documents without their complex, inflexible and expensive manufacturing processes.

In some embodiments, the spring component is homogeneous with respect to its foam composition and properties. In other embodiments the spring component's foam composition and properties may vary.

In addition, the present invention provides examples of cushioning devices comprising at least one spring component as described above, methods of manufacturing spring components according to the present invention, and methods of manufacturing cushioning devices comprising said spring components.

BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is a perspective view of an integrally formed foam spring component in accordance with one embodiment of the present invention;

Fig. 2 depicts a similar view in accordance with another embodiment of the present invention; Fig. 3 depicts a perspective view of a mattress incorporating the spring component of Fig. 1; Fig. 4 depicts an end elevation of the mattress of Fig. 3; Fig. 5 depicts a side elevation of the mattress of Fig. 3; and

Fig. 6 depicts a pillow insert comprising a spring component according to the present invention. DETAILED DESCRIPTION

DEFINITIONS

The following terms are used in describing and claiming spring components in accordance with the present invention.

Height: the axial dimension between the top and base surfaces of a spring element and that of a link parallel to a spring component height.

Breadth: the transverse dimension across a spring element or a link and perpendicular to the axial dimension.

Length: the longitudinal dimension along a spring component and perpendicular to the axial and transverse dimensions. Fig. 1 depicts an integrally formed foam spring component 2 according to the present invention. The foam spring component 2 comprises a chain of foam spring elements 8 connected by integral links 10 between neighbouring spring elements. The spring elements 8 possess a top surface 4 and a base surface 6 and at least one side surface 7; in preferable embodiments the top surfaces 4 of the spring elements 8 in a spring component 2 are coplanar with each other, and likewise in preferable embodiments the base surfaces 6 of the spring elements 8 in a spring component 2 are coplanar with each other. It will be noted that the breadth (b) of the links 10 is narrower than that (B) of the spring component 2. Cushioning devices according to the present invention may comprise one or more foam spring components 2 comprising these features.

The skilled person will appreciate the fact that because the spring elements 8 and links 10 are integrally formed in a spring component 2, when pressure is exerted on one spring 8, the force exerted will be distributed across the spring component 2 via the links 10, so that neighbouring spring elements in the spring component 2 can help provide support even if weight is not exerted directly on them. (In embodiments where the link 10 comprises the entire height from the top surface 4 to the base surface 6, the load on any given spring 8 will be distributed by the links to neighbouring spring elements 8 as soon as any deformation of the given spring 8 occurs.) At the same time, a customer inspecting a cushioning device comprising such spring components 2, if they press down on it, will be able to feel the individual spring elements 8, thus giving the familiar tactile experience of traditional spring cushioning devices.

It should be noted that with respect to the number of spring elements 8, the spring component 2 depicted in Fig. 1 is simply an example of one embodiment, and the integrally formed foam spring components 2 could have more or less spring elements 8 as appropriate. Providing a number of spring elements 8 in an integrally formed spring component 2 for a spring component greatly simplifies the process of manufacturing cushioning devices, since the spring elements 8 do not have to be set in place on an individual spring-by- spring basis. In addition, by cutting the spring component 2 at one of the links 10, two shorter spring components 2 can be produced from a longer spring component 2.

In the spring component 2 depicted in Fig. 1 the foam spring elements 8 directly abut, and are integral with, their neighbouring spring elements, the links 10 comprising the meeting surfaces of the two. Longer links would provide more space between the spring elements 8. The spring component 2 depicted in Fig. 1 is essentially elongate, with the foam spring elements 8 forming a chain extending in lengthwise along the spring component, each spring 8 being linked to two neighbouring spring elements, save at the beginning and end of the spring component.

This is only a single example, however, and in fact spring components 2 do not necessarily have to extend in a single longitudinal direction. For instance, whilst in the depicted example the links 10 are at 180° from each other as measured from the centre of the spring elements 8, this does not have to be the case. If it were desired to produce a single spring component 2 which extended through a 90° corner, then providing a spring component 2 in which most of the spring elements 8 had links 10 arranged at 180° from each other, with one spring element 8 having a link 10 arranged at 90° from a neighbouring spring element, would provide such a solution. Likewise, spring components 2 could extend through other corners simply by selecting an appropriate angular separation of links 10 at the "corner- turning" spring element 8. Similarly, if it were desired that a single spring component 2 provide multiple rows of spring elements 8 then modifying the angular separations of the links 10 at the spring elements 8 at the end of the rows could allow the spring component 2 to "double back" on itself.

The spring components 8 have a uniform cross-section, without any bores or other apertures.. The embodiment depicted in Fig. 1, for instance, presents cylindrical spring elements 8 with an essentially circular cross-section having the one side surface 7. A range of different shapes for spring elements 8 could be used; for instance, the spring elements could be prismatic with triangular, or quadrilateral, or pentagonal, or hexagonal, or heptagonal, or octagonal, or be any the cross section shape that the manufacturing methods used are capable of producing (particularly regular polygons).

Fig. 2 depicts an example of a spring component 2 with spring elements 8 with a hexagonal cross-section; as in Fig. 1 the spring component 2 comprises spring elements 8 and links 10, and the spring elements define a top surface 4 and a base surface 6. Since the spring elements 8 have a polygonal cross-section, they have six side surfaces 7, defined defined by side 12 and flat faces 14. (Conversely, the spring elements 8 in Fig. 1 have ther one continuously curved side surface 7.

The links 10 in spring component 2 with spring elements 8 of a polygonal cross-section are located between meeting edges of faces 12 and 14 of neighbouring spring elements, as in Fig. 2; polygons for which such side-to-side links 10 would be convenient include quadrilaterals, hexagons, octagons and so on. Alternately, the links 10 in spring components 2 with spring elements 8 of a polygonal cross-section could be formed between opposed meeting faces 14 of neighbouring springs meet each other; polygons for which such face-to-face links 10 would be convenient include hexagons, octagons and so on. Alternately, the links 10 in spring components 2 with spring elements 8 of a polygonal cross-section could occur where the side 12 of one spring 8 meets the face 14 of a neighbouring spring 8; polygons for which such side-to-face links 10 could prove convenient include triangles, pentagons, heptagons and so on.

The embodiments of the invention shown in Fig. 1 and 2 show the links 10 extending the full height between the top surface 4 and base surface 6 planes of the spring elements 8. Alternate embodiments include non-full height extension (e.g. 25% to 75%of the notional full height) links 10 between adjacent spring elements 8; such partial, and/or intermediately positioned links 10 facilitate spring element separation, if so desired during the assembly of a cushioning device.

Utilising spring elements with different cross-sections can be a means of modifying the properties of a cushioning device comprising the spring components 2 because it will change the extent to which they can be tessellated during assembly and will change the size and geometry of the gaps between spring elements 8, both within a spring component 2 and between spring components 2.

Air flow can be promoted by the axial intercial vents 9 provided by the spaces between adjacent spring components.. Air flow can also be promoted by forming the spring component 2 from an air-permeable foam.

As mentioned, the present invention also provides cushioning devices 16, comprising at least one spring component 2 as described above. When spring components according to the present invention are used in a cushioning device, typically the integral foam spring components 2 are arranged such that when the cushioning device is installed in furniture and sat upon, laid upon or leaned against, the primary component of force is directed along the axis from the top surface 4 to the base surface 6. In examples where cushioning devices comprise multiple spring components, the spring components may have different properties. For example, if it is desirable to provide different levels of support in different regions of the cushioning device, this may be accomplished by utilising firmer foam for some the spring component(s) 2 or and less firm foam for others. For instance, in a cushioning device individual foam spring components 2 can be selected to provide additional support in regions of the cushioning device where it is required.

A range of different properties and tests are used to describe the properties different varieties of foam utilised in cushioning devices, including:

• Density, weight per unit volume. Indentation Force Deflection (IFD) or Indentation Load Deflection (ILD), a means of measuring load bearing capacity (firmness or stiffness). This is measured by placing an indenter of known area being driven into a section of a foam sample of a specified size, and until it reaches a deflection of a set percentage of the original thickness of the sample (so, for instance, if the set percentage is 25% and the foam sample is 8 centimetres thick, an indentation 2 centimetres deep is desired). The force in pounds required to hold the foam at this indentation after one minute is recorded. The IFD value is typically reported as force per area at a given percent deflection of the foam. (So, for instance, the IFD of a foam at 25% deflection is referred to as the 25%R IFD.)

Compression Load Deflection (CLD) is another means of measuring firmness, like IFD. The difference is that whilst IFD is tested by compressing a section of a sample beneath an indenter, CLD is measured by compressing an entire foam sample beneath an indenter.

Sag Factor/Modulus is the ration of the 65%R IFD and the 25%R IFD, and gives an indication of cushioning quality.

Recovery Ratio is the ratio of 25%R IFD released to 25%R IFD initial when measuring IFD values first at 25% deflection, then at 65% deflection, and then released back to 25% deflection.

Guide Factor is the ratio of 25%R IFD to density and is expressed in whole numbers. It is considered useful for the purpose of comparing the relative firmness of foams with different densities.

% Compression Set is a measure of the permanent deformation of a foam after it has been compressed between two metal plates for a controlled time period and temperature condition. (The standard conditions are 22 hours at 70°C).

Tensile Strength is a measure of the amount of force required to break a standard- sized area of foam as it is pulled apart.

Elongation is a measure of the extent to which foam can be stretched before it breaks and is expressed as a percentage of its original length. Standard tests for elongation often involve measuring it at the same time as tensile strength is measured.

Permeability is a measure of the volume of air per minute that can be pulled through a standard-sized sample of foam. A Frazier permeability device is often used to assess permeability. • Impact resilience or "ball rebound" is a measure of the elasticity, bounce, or springiness of foam, and is expressed as a % of return or % of resilience. Standard procedures for measuring this involve dropping a steel ball of standard size and weight on a standard-sized foam sample.

· Clickability is the rating of a foam's ability to recover from a die-cutting operation. Its inverse property is weldability.

• Bond strength is a measure of the force needed to separate two foam substrates that are laminated together.

• Fatigue is a measurement of the loss in load bearing capability of a foam. This may be assessed via static fatigue testing, in which a foam is deflected for an extended period of time and then retested, or through roller shear fatigue, in which a stainless steal roller is used to dynamically fatigue a sample of foam for thousands of cycles, or constant force pounding fatigue in which a flat horizontal indenter foot is used to fatigue a foam sample for thousands of cycles, or any other suitable fatigue testing method.

Of course, many of these properties may vary with age, and consequently means have also been developed to test these. Steam autoclave aging is a means of characterising the aging properties of a foam via treatment in a steam autoclave, followed by re-testing of physical parameters. Dry heat aging is a similar means which involves subjecting a foam to dry heat in an air-circulating oven.

Thus, when it is desired to create a cushioning device providing greater support for some portions of the body than others, individual foam spring components 2 may be selected with the above values varying from spring component to spring component, and arranged as components of the cushioning device item accordingly. For example, the region of a cushioning device for a chair where the buttocks rest is usually supporting more body weight, and so individual foam spring components 2 arranged there may be firmer in order to provide more support. In particular, many manufacturers produce ranges of foams for cushioning device use which vary in parameters such as density, ILD and CLD.

A more complex example of a customised cushioning device comprising such foam spring components 2 would be a zoned mattress, in which different zones of the mattress have different ILD values. Foam spring components 2 according to the present invention could be incorporated into a mattress such that spring components 2 of differing ILD values are placed in different zones, so that the assembled mattress can accommodate the different force impositions generated by, for example, the heels, legs, buttocks, torso and head of a human body lying on the mattress.

Particularly useful types of foam which may be utilised include, but are not limited to, combustion modified high resilience foams, combustion modified ether foams, and visco- elastic foams. Examples of such foams include those marketed as Richguard™ Extra CM Polyether, Richguard™ Combustion Modified High Resilience and Celcius™ Combustion Modified Visco-Elastic foams. Such foams have densities ranging from 21 to 75 kgm ^" (tested via ISO 845), ILD values ranging from 40 to 240 Newtons (ILD 40%, assessed as per EN ISO 2439/B), and CLD values ranging from 1.0 to 6.0 kPa (CLD 40%, assessed as per ISO 3386/1). These ranges are not intended to describe the functional limits of the present invention but merely illustrate the range of properties available in a typical commercially- available series of foams. Other sources of foam include "rebond", materials produced by cutting up and gluing together foams from a waste product. One means by which a foam's properties may be modified is by the addition of filler materials known to the market such as Styrofoam or gel beads, or through the production of blends of foam and another material such as the foam/gel blends currently known on the market. It is possible to produce a spring component 2 whose spring elements 8 have varying properties by, for example, adding a filler material to an intermediate section of the spring component 2 but not to the end spring elements.

Examples of suitable cushioning devices which the spring components may be used include (but are not limited to) mattresses, mattress toppers, pillows, cushions and the like. Fig. 3 depicts a mattress 16 comprising foam spring components 2 according to an embodiment of the invention. As well as the spring components the mattress 16 comprises a mattress top 20 and a mattress base 18. The mattress top 20 is attached to the top surface 4 of the spring components 2, and the mattress base 18 is attached to the base surface 6 of the spring components 2, keeping the spring components in place. This means of attachment may be as simple as utilising adhesive to permanently affix the spring components 2 in place. Under usual circumstances the mattress top 20 faces upwards when the mattress 16 is installed on the bed and the mattress base 18 faces the bed base, but it will be appreciated by the skilled person that the mattress could equally be used the other way up. The top and base layers may be made of foam. In use the mattress 16 is usually provided with a protective cover 22. The resultant mattress can be any size desired, from standard single (90 x 190 cm) and below to standard super king-sized (180 x 198 cm) and above; producing a mattress 16 of a desired size is as simple as providing a top 20 and a base 18 of the appropriate size and utilising the appropriate number of individual foam spring components 2. In this particular example the spring elements 8 are shown as being cylindrical with a substantially circular cross-section but the skilled person will appreciate that this is not a requirement. Likewise, the skilled person will realise that instead of the spring components 2 being arranged in parallel ranks with one another, they could be arranged in a staggered conformation, which will result gaps between the spring elements 8 in neighbouring spring components 2 being of a different size and geometry. The mattress top 20 and mattress base 18 of the mattress could be flat, or profiled, or contoured cut with designs to give a softer feel and perforated to provide air flow to the mattress.

In the example shown in Fig. 3 it is seen that the spring components 2 are of the same length as the shorter sides 30 across the mattress 16. Alternately, shorter spring components could be used and arranged next to each other - for example, two spring components half the length of the shorter sides of the mattress 16 could be used. Alternately, longer spring components may be provided and cut down to the length along the mattress sides. Alternately, the spring components 2 could be arranged such that they extend parallel to the longer sides 32 of the mattress 16 instead of the shorter sides 30 of the mattress. (In mattresses where the sides 30, 32 are of equal length then this is of course arbitrary.) It is even conceivable that in some mattresses some spring components may be arranged lengthwise and some may be arranged crosswise.

Fig. 4 depicts the example mattress 16 in an end elevation. As can be seen, the spring components 2 extend in a direction parallel to the mattress side 30, so that each spring 8 is connected via a link 10 to its neighbouring springs in this direction. (In examples where multiple spring components 2 shorter than the length of the side 30 are arranged to extend along the length of the side 30 then there will of course be discontinuities between one spring component 2 and the next.)

Fig. 5 depicts the example mattress 16 in a side elevation. Since the spring components 2 extend in a direction perpendicular to the mattress side 32, each spring 8 is not connected to its transversely neighbouring spring elements in this direction (save through the intermediate connection via the mattress top 20 and mattress base 18 to which the spring elements are adhered). Assuming each individual spring component 2 has homogeneous foam properties, which need not be homogeneous from spring component to spring component' then the properties of this example mattress 16 will be consistent along a direction parallel to mattress side 30 whilst they may, at the option of the manufacturer, vary on a spring-by- spring basis along a direction parallel to mattress side 32.

The example of the mattress 16 illustrates how the present invention offers a hybrid system of producing a cushioning device utilising foam as the cushioning means. It is much faster and simpler process to assemble this mattress 16 than to go through the time consuming process of positioning individual spring elements in place, each of which must be individually secured somehow, and yet at the same time the system offered provides much more customisability when it comes to the properties of the end product than simply providing a single, unitary block of foam.

Fig. 6 depicts a pillow insert 24 according to the present invention, in which there is provided a number of linear foam spring components 2 confined in a webbing or bag 26 sized to confine them in place, which can be inserted into a pillowcase 28 to provide a pillow. This is an example of how the skilled person can apply spring components, which could be as simple as a single foam spring component 2 according to claim 1, to cushioning devices beyond mattresses.

A major advantage of spring components 2 according to the present invention is their ease of manufacture. The process of manufacturing is simply taking a foam body and cutting it into the shape of a spring component 2. In cases where a particular depth of the spring component 2 (as measured from the top surface 4 to the base surface 6 of the spring elements 8) is desired, the foam body may be cut to the desired thickness before the integral foam string(s) 2 is cut into shape; for example, a slitting machine could cut a block into several pieces of the desired thickness, and the resultant pieces could be arranged on a vertical cutting machine and cut to shape. Alternately, a thicker than desired foam spring component(s) 2 may be produced and then cut to the desired thickness; for example, the foam block could be placed on a contour cutting machine, the spring component(s) 2 could be cut to shape, and then the spring component(s) could be sliced to the desired thickness. These manufacturing methods advantageously allow multiple spring components to be produced from the same foam block, in the same process. Advantageously, the cutting machine utilised to produce the individual foam spring components 2 may be computer-controlled. For example, it may be a VCC cutting machine, a vertical continuous blade foam cutting machine operated via a computer programme. Examples of such programmes would include CAD/CAM (Computer Aided Design/Computer Aided Manufacture) operating systems, including but not limited to CNC (Computer Numerical Control) systems and those systems developed by F&K GmbH, may be utilised to produce the individual foam spring components 2.

The process of manufacturing a mattress 16 according to the present invention could be similarly simple. One example of a suitable manufacturing method would be to attach the spring components 2 in the desired configuration to the mattress base 18 via adhesive applied between the mattress base 18 and the base surfaces 6 of the spring elements 8, and then the mattress top 20 could be attached to the top surfaces 4 of the spring elements 8 via adhesive applied between the mattress top 20 and the top surfaces 4. Alternatively, the spring components 2 could be attached to the top first and the base second, or to both simultaneously. The skilled person will be aware that instead of utilising adhesive any other means of securing spring components in place between a mattress base and mattress top can be utilised. In a preferable embodiment, the mattress base 18 or the mattress top 20 may be made of a viscoelastic foam with punched holes for air flow.