WO1998027848A1

WO1998027848A1 - Inner sprung articles and methods of formation

Info

Publication number: WO1998027848A1
Application number: PCT/NZ1997/000170
Authority: WO
Inventors: Lyn Craig Turner
Original assignee: Sleepyhead Manufacturing Company Limited
Priority date: 1996-12-23
Filing date: 1997-12-23
Publication date: 1998-07-02
Also published as: AU5350998A

Abstract

An inner sprung article (1) and a spring (2) for use in the production of an inner sprung article (1), wherein the article contains a plurality of individual springs (2) and at least one cushioning layer (6). At least one end of the springs (2) is attached to at least one sheet of material (4) and the sheet of material (4) is engaged with the cushioning layer (6) to maintain the spring end in relative position with respect to the cushioning layer (6).

Description

INNER SPRUNG ARTICLES AND METHODS OF FORMATION

Technical Field

This invention relates to articles containing internal springs and to methods of formation of such articles. In particular, this invention is directed to inner sprung mattresses such as those incorporating coil springs within the mattress. The invention should not be seen to be limited to mattresses and the production of mattresses, however.

Background Art

A typical inner sprung article, such as a mattress, provides a central core of springs between a foam sandwich. This is then covered with suitable coverings to complete the mattress. When the article is intended for seating, such as a chair, the typical spring cushioning simply involves a base support for the springs which are then covered by cushioning and other suitable coverings.

In the past a number of attempts have been made to provide methods for keeping the springs in a substantially constant relative position with respect to the foam. Such methods have included the use of fabric pockets such as described in international patent application PCT/NZ96/00042 or the use of coils with the end set into the foam sandwich as disclosed in international patent application PCT/NZ95/001 37.

SUBSTITUE SHEET (Rule 26) Other prior art methods and devices include that disclosed in US patent No. 3,070,814 to A J Withoff entitled Spring-Cushion Structures. This US patent is generally directed to a spring base for upholstery cushioning material. The coiled springs of use are tied together, as can clearly be seen in Figure 7. The individual springs are not and cannot operate independent of one another. As a result independent spring response cannot be achieved to any extent. The face of the springs may be dipped into a bath of latex adhesive and then applied directly to a fibrous upholstery cushion which may be adhesively lined with a fabric such as cottonet. Such direct interaction of the spring face with the cottonet and/or fibrous upholstery has the disadvantage that the spring face can readily detach on consistent use. This disadvantage is somewhat allayed by the provision of the tied springs which form a drum head over which the cushioning is placed. The need to tie the springs also causes decreased production efficiency of the articles.

A similar structure is disclosed in US patent No. 3,325,833 also to A J Withoff. This US patent is a continuation in part of US patent No. 3,070,814 referred to above. USP 3,325,833 discloses inner sprung mattresses which contain a vast amount of centrally located springs which are directly adhered to the cushioning material, or insulator sheet on the cushioning material, by a thick viscous adhesive. The outer border of the springs are tied to a border wire located adjacent the periphery of the mattress. It is clear from the disclosure of this US patent that the requirement of tying the springs together as disclosed in US patent 3,070,814 referred to above, is eliminated by locating the springs in a closer relationship. This can be achieved by arranging the springs in

SUBSTITUE SHEET (Rule 26) parallel rows in staggered relation. In fact, it is stated that it is preferred to have the springs in one row in part fitting into the space between adjacent springs in an adjacent row. The method disclosed in this US patent therefore requires a vast number of springs with a consequent increase in production cost, and the direct contact of the springs to the cushioning material has the disadvantages discussed previously in relation to USP 3,070,814.

US patent No. 3,71 9,963 to C G Bullock Jr, discloses a mattress which comprises an outer foam pad and an underlying spring assembly. The process to produce the mattress involves producing a foamable material in an open top mould and then positioning an open mesh fabric and an overlying spring assembly in floating relation on the foaming material during the foaming process. This produces a product in which the mesh fabric is essentially embedded, and thereby secured, in the upper crust of the foamed material and the terminal portions of the spring assembly rest upon and adhere to this upper crust without significantly penetrating. Thus, the terminal ends of the spring base are integral with the foamed material. The process requires the springs to be positioned during the foaming process in a position so they can become incorporated into the foam and mesh materials.

US patent No. 2,626,408 to Arthur Wesley discloses the manufacture of an inner spring and foam rubber mattress. The method involves the incorporation of the ends of the spring coils into the cushioning slab of the foam rubber of the mattress. As a result, the spring ends can tend to pierce the foam rubber slab. In addition, there is

SUBSTITUE SHEET (Rule 26) considerable foam rubber wastage in the manufacturing process. This disclosure is similar to that of PCT/NZ95/001 37 discussed previously.

Many of the prior art methods seek to provide support for the cushioning by linking the inner springs together with the result that the individual behaviour of the individual spring coils are affected by the movement of other coils to which they are attached. In other cases, the prior art methods seek to retain the ability of the individual springs to move independently of each other while maintaining their position in relation to the cushioning used. However, the known methods lead to substantial disadvantages in processing techniques, the amount of components, such as springs or foam, used, and in relation to the durability of the mattresses or other cushioning produced.

Object of the Invention

It is an object of the present invention to provide an inner sprung article which overcomes at least some of the disadvantages of the prior art articles and to provide a method by which such articles can be produced which goes at least some way to meet processing requirements.

Summary of the Invention

The invention, in a first aspect, is an inner sprung article including a plurality of individual springs and at least one cushioning layer; wherein

SUBSTITUE SHEET (Rule 26) at least one end of the springs is attached to at least one sheet of material; and wherein the sheet of material is engaged with the cushioning layer such that the spring end is maintained in a relative position with respect to the cushioning layer.

Preferably the sheet of material is sufficiently resilient to maintain a substantially planar form when attached to the spring.

Preferably the sheet of material has a periphery which extends beyond the periphery of the spring when viewed along its compression axis.

Preferably the sheet of material is formed of a reinforced web material, spun polyester material or of a plastics material.

Preferably the spring ends are attached to the sheet of material using a flexible adhesive.

Preferably the flexible adhesive is a PVC based adhesive.

Preferably both ends of the springs are attached to a sheet of material.

Preferably the inner sprung article further includes a spring insulation layer which is attached to the cushioning layer, and the sheets of material are engaged with the insulation layer.

SUBSTITUE SHEET (Rule 26) Preferably the insulation layer is a coconut fibre material.

Preferably the coconut fibre material is coir.

Preferably the individual sheet of material is in the form of an elongated strip of material adapted to attach to an end of a plurality of aligned springs.

The invention, in a second aspect, comprises a method of forming an inner sprung article which includes the steps of:

providing a plurality of individual springs; providing a cushioning layer; providing individual sheets of material; attaching an end of the springs to a sheet of material; and connecting the sheet of material to the cushioning layer to position the end of the spring relative to said cushioning layer.

Preferably the springs are attached to the individual sheets of material with a flexible adhesive.

Preferably the flexible adhesive is PVC based adhesive.

Preferably the method further includes the step of attaching an insulation layer to the cushioning layer such that the sheets of material are attached to the cushioning layer via the insulation layer.

SUBSTITUE SHEET (Rule 26) Preferably the individual sheets of material are elongated strips of material adapted to attach to an end of a series of aligned springs.

In a third aspect the invention comprises a spring for use in a cushioned article, wherein the spring is a coil spring having a cap at at least one terminal end of the spring, the face of the cap distal to the spring being substantially planar and lying in a plane substantially normal to the compression axis of the spring, the dimensions of the cap being such that the periphery of the cap extends beyond the periphery of the coil spring when viewed along the compression axis of the spring, and wherein the cap is formed of a flexible material having sufficient rigidity to maintain the substantially planar face.

Brief Description of Drawings

The invention will now be described with reference to the following drawings in which:

Figure 1 : Shows a cross-sectional elevation view through a spring mattress in accordance with one embodiment of the invention;

Figure 2: Shows a plan view of a portion of the mattress of Figure 1 ;

SUBSTITUE SHEET (Rule 26) Figure 3: Shows a cross-sectional view through the portion of the mattress indicated at A-A as shown in Figure 2;

Figure 4: Shows a plan view of an alternative embodiment of the invention.

Detailed Description of the Invention

The invention is generally directed to the provision of an inner sprung article, such as a mattress, seating or the like. The invention is, however, particularly directed to the provision of inner sprung mattresses.

In the particular field of mattress production it is advantageous to be able to provide a mattress which allows for posture adaptation. This is sometimes referred to as "posturisation" and involves the provision of firm support and flexible support in particular areas of the mattress. In this way effects such as "roll together" can be avoided on two-person mattresses and also lumbar, hip and shoulder support can be provided to the user. This is usually provided by using springs of varying compression ability in specific areas of the mattress.

The ability to provide such posturisation is limited by linking together of springs as the ability of individual springs to react to pressure will be hindered by flow-on effects from other springs. In addition, too many springs within the mattress reduces the ability of springs to act individually as well as increasing the cost of mattress production. It is

SUBSTITUE SHEET (Rule 26) also desirable that the springs be held in substantially constant position relative to the cushioning of the article in order to maintain the spring response in particular areas.

The present invention achieves these desirable features by the provision of individual sheets of material being attached to at least one terminal end of the springs used in the article. In the case of an inner sprung mattress, the individual sheets of material will preferably be attached to both terminal ends of the springs used in the mattress and then attached to the opposed layers of cushioning material. In this way, reversibility of the mattress is allowed for. These individual sheets of material which are attached to the terminal ends of a spring are fixed to the cushioning of the article via the attached sheets of material allowing the spring to be held in position relative to the cushioning and also allowing the provision of a layer of material between the cushioning and the spring. If an insulation layer of material (e.g. cottonet or coir) is added to the cushioning, the sheets of material add a further layer between the spring ends and the cushioning. The sheet of material presents a broad face to the cushioning layer thus ensuring firm and secure attachment of the spring to the cushioning layer.

The use of individual sheets of material attached to the individual springs also allows significant advantages in the manufacture of such inner sprung mattresses. The sheet of material can be attached to the spring and then the cushioning is attached to the individual sheet of material. As a result, it is possible for a conveyor belt-type system to be

SUBSTITUE SHEET (Rule 26) utilised in the manufacture of inner sprung mattresses having posture adaptation as will be described further below.

With reference to Figure 4, it is also possible for the individual sheets of material 4 to take an elongated form (e.g. a strip of material) which preferably has width sufficient to encompass one spring 2 when viewed along the spring's compression axis. This will limit the spring response in one direction only while maintaining the desirable attributes of secure positioning and enhanced processing capability. The width of the material strip can incorporate 2 or 3 springs, but this is less preferred.

With reference to the attached Figures, Figure 1 shows an inner sprung mattress 1 in which a plurality of individual springs 2 are positioned to provide a spring core to the mattress 1 . In the mattress 1 , the springs 2 are shown as coil springs however, as will be known to a person skilled in this particular art, a variety of spring types (e.g. Z springs) could be used as desired.

The springs 2 are shown having terminal ends 3, 7 which are attached to individual sheets of material 4. The terminal ends 3, 7 of the springs 2 may be attached to the individual sheets of material 4 by any suitable means as already known in the art. Attachments such as providing a sleeve within the individual sheet of material 4 into which the terminal ends 3 of the springs 2 may fit may also be used for example. It is particularly preferred that the terminal ends 3, 7 be adhered to the sheets of material 4 using a flexible adhesive. Non-flexible adhesives, such as glues generally, may be used, however flexibility in the adhesive

SUBSTITUE SHEET (Rule 26) is preferred as this gives greater durability and allows the springs to move slightly in a lateral direction (i.e. along the plane of the cushioning 6) without affecting the security of the attachment. The preferred adhesives are generally PVC based as will be known in the art. Latex, or polyurethane adhesives and the like may also be used.

The individual sheets of material 4 are attached to the cushioning 6 of the mattress 1 . The material 4 may be connected to the cushioning 6 by any means as will be known in the art however, again, the use of suitable adhesives are preferred. The sheets of material may, however, be attached via sewing, stapling, pop rivets or the like to the cushioning material 6.

The individual sheets of material 4 are preferably formed from a webbing-type material suitable for use with the particular adhesive selected. The material is preferably formed from a material having sufficient rigidity to maintain a substantially planar aspect when positioned on a spring as generally shown in the Figures. Material such as a reinforced webbing material, spun polyester or a plastics material would generally be considered suitable. Other materials as will be known in the art may also be used. If, in a less preferred option, a sheet of material having little rigidity is used, then the material would need to be attached via staples, sewing or the like. This is less preferred as increased processing difficulties are incurred.

The cushioning material 6, 8 is preferably a foam material as will again be known in the art. Alternative forms of cushioning may also be

SUBSTITUE SHEET (Rule 26) used, such as flexible rubber pads and the like, however a foam rubber type material is preferred.

By utilising the intermediate layer of material 4 between the terminal ends 3, 7 of the springs 2 and the cushioning layers 6, 8, improved adhesion of the springs to the cushioning layer 6 is provided. The relatively small contact area provided by the terminal end 3, 7 of the springs 2 may be insufficient for direct adhesion to cushioning material. This is particularly so when utilising foam rubber-type materials which are inherently relatively weak. Repetitive use of the mattress will produce forces on the terminal ends 3, 7 of the spring 2 which will tend to tear the spring from the cushioning material 6, 8, or drive the end through the foam layer. By utilising the layer of material 4 over a broader area of the cushioning material 6, 8 the broader face of the material allows a greater degree of contact over a broader face of the cushioning material 6, 8 which allows stronger adhesion via greater contact area. With the preferred combination of flexible adhesive plus a suitably resilient material used for the sheet of material 4, the springs 2 are firmly linked to the cushioning material 6 and the resilience of the total structure is maximised.

As will be readily appreciated by a person skilled in this art, the embodiment of the invention as shown in Figure 1 , which shows parallel layers of cushioning 6, 8, should not be seen to be limiting. It is within the scope of the invention that the lower layer of cushioning 8 may be dispensed with and the terminal end 7 of the springs 2 suitably attached to a base layer of metal, wood or plastics material or the like when the

SUBSTITUE SHEET (Rule 26) invention is used for the production of seating for example. The terminal end 7 of the spring 2 would be attached to the base layer by any suitable means such as brackets, staples, ties or the like as will be known in the art.

With reference to Figures 2 and 3, a single piece of material 4 may be utilised adjacent the terminal end 3 of the spring 2. The individual sheet of material 4 is, in the preferred embodiment, adhered using a suitable adhesive 5 at the terminal end 3 of the spring 2 at a substantially central position within the material 4.

The springs of use in the cushioned article are preferably coil springs on which the sheet of material (as indicated at 4 in Figure 1 ) effectively forms a cap to the spring. As will be readily apparent to a person skilled in this particular art the sheet of material will need to be formed of a material sufficiently resilient to maintain an essentially planar form in order for the cushioning layer to be placed on the sheet of material and be effectively engaged to it. It is a particularly preferred feature that the sheet of material forms a cap which has, and can maintain, a substantially planar face for engagement with the cushioning material. This planar face will be the face distal to the spring body as can readily be seen in the Figures. In a particularly preferred embodiment therefore, there is provided a coiled spring having a sheet of material adhered to at least one terminal end of the coiled spring such that the sheet of material forms a cap to the spring. The cap may be attached to the spring by a variety of methods, and may take any shape (e.g. square, circle, diamond

SUBSTITUE SHEET (Rule 26) etc.) as may be desired. The cap may, for example, contain a recess into which the spring end can be inserted for example.

As a result of the presence of the spring cap, the engagement face of the spring is enlarged thus ensuring adequate attachment of the individual spring to the cushioning layer. As can be seen clearly in Figure 1 , the cap is the sheet of material indicated generally at 4 which may be adhered to the terminal end 3, 7 of the spring 2.

The cap is preferably formed of a spun polyester type material, however a variety of flexible yet resilient plastics materials or alternative materials as will be known in the art may also be used.

A further preferred feature is the optional inclusion of a layer of a natural fibre, such as coconut fibre material (e.g. coir). This material is attached via known means to the cushioning material and the sheet of material then attaches to the material fibre. Cottonet, or similar materials, may also be used. The intention is to provide a layer with tension or sheer strength in the plane of the cushioning material and with good flexibility in the compression direction.

With reference to Figures 1 to 3 generally, the process for producing inner sprung mattresses according to the invention allows the production of inner sprung mattresses, which will preferably have posturisation features, with improved efficiency over prior art methods.

SUBSTITUE SHEET (Rule 26) The preferred process for producing the mattresses includes the steps of dipping at least one of the terminal ends 3, 7 of the springs 2 in a flexible adhesive and then applying to those terminal ends 3, 7 the individual sheets of material 4. As will be readily apparent, the action of dipping the terminal ends 3, 7 into a suitable adhesive is not a limiting step, as the adhesive may be applied by a variety of means such as brushing or spraying as will be known in the art. As a result of this step the "cap" to the spring is formed as referred to previously.

Once the individual sheets of material 4 are attached to the terminal end or ends 3, 7 of the springs 2, the individual sheets of material 4 are attached to the cushioning layer 6, 8. The connection of the sheet of material 4 to the cushioning layer 6, 8 will necessary depend on the type of cushioning layer used, however it is envisaged that the use of a suitable adhesive will be preferred as has been described previously. Adhesive may be applied to either the material 4 or to the layer 6, 8 with application to the layer 6, 8 preferred. Any suitable application technique may be used. Alternative attachment techniques such as sewing, stapling and the like may also be utilised if desired. This is particularly so if the material 4 lacks the rigidity needed to maintain the planar aspect. Such materials are not preferred as discussed previously, but could be used if desired.

In a less preferred alternative, the individual sheets of material 4 may be pre-attached to the cushioning material 6, 8 and the terminal end or ends 3, 7 (which would then include applied adhesive) then adhered to the sheets of material 4. This is, however, not a preferred option as it

SUBSTITUE SHEET (Rule 26) will inherently incur difficulties in positioning the springs in relation to the sheets of material 4.

As will be readily apparent, the process of producing inner sprung mattresses in particular may be automated via the use of this production technique. The individual springs 2 together with the adhered sheets of material 4 may be positioned in sequence and an extended layer of cushioning material may be brought into contact with the sheets of material 4. Opposed layers of cushioning 6, 8 may be applied to opposed ends of the springs plus the "cap" material 4 in a sandwiching technique for example. Advantageously, pressure will be applied to the cushioning layer to firmly attach the layer or layers to the individual sheets of material 4, and thus the springs 2, for a suitable time to ensure adequate attachment.

Suitable times and pressures may be readily determined by a skilled person and will vary dependent on the materials used. Following this, lengths of the preformed mattress may be cut as desired. It will be readily apparent that springs of varying resilience may be positioned in sequence as required by the manufacturer in order to gain a posturisation effect to the mattress. The mattresses would be cut from the continuous length of cushioning material and springs at predetermined intervals.

As a result of this procedure, the ability to obtain inner sprung mattresses having desired posturisation effects can be automated and prior difficulties with individual positioning of springs and attachment of these springs, at times by hand, are overcome.

SUBSTITUE SHEET (Rule 26) The final form of the mattress would be achieved by covering the cushioning layers with a suitable covering material as will be known in the art.

The forgoing describes the invention together with the preferred forms of thereof. Alterations or modifications as will be obvious to a person skilled in the art are intended to be included within the scope of the invention as is defined in the appended claims.

SUBSTITUE SHEET (Rule 26)

Claims

CLAIMS:

1 . An inner sprung article including a plurality of individual springs and at least one cushioning layer; wherein at least one end of the springs is attached to at least one sheet of material; and wherein the sheet of material is engaged with the cushioning layer such that the spring end is maintained in a relative position with respect to the cushioning layer.

2. The article of claim 1 wherein the sheet of material is sufficiently resilient to maintain a substantially planar form when attached to the spring.

3. The article according to claim 1 or claim 2 wherein the sheet of material has a periphery which extends beyond the periphery of the spring when viewed along its compression axis.

4. The article according to any one of the preceding claims wherein the sheet of material is formed of a reinforced web material, a spun polyester material, or a plastics material.

5. The article according to any one of the preceding claims wherein the spring ends are attached to the sheet of material with a flexible adhesive.

SUBSTITUE SHEET (Rule 26)

6. The article according to claim 5 wherein the flexible adhesive is a PVC based adhesive, a latex adhesive, or a polyurethane adhesive.

7. The article according to any one of the preceding claims where both ends of the springs are attached to a sheet of material.

8. The article according to any one of the preceding claims wherein the article further includes a spring insulation layer which is attached to the cushioning layer, and the sheets of material are engaged with the insulation layer.

9. The article according to claim 8 wherein the insulation layer is a coconut fibre material.

10. The article according to any one of the preceding claims wherein the sheet of material is an elongated strip of material adapted to attach to an end of a plurality of aligned springs.

1 1 . A method of forming an inner sprung article including the steps of: providing a plurality of individual springs; providing at least one cushioning layer; providing individual sheets of material; attaching an end of the springs to a sheet of material; and connecting the sheet of material to the cushioning layer to position the end of the spring relative to said cushioning layer.

SUBSTITUE SHEET (Rule 26)

1 2. The method according to claim 1 1 wherein the spring ends are attached to the sheets of material using a flexible adhesive.

1 3. The method according to claim 1 2 wherein the flexible adhesive is a PVC based adhesive, a latex adhesive, or a polyurethane adhesive.

14. The method according to any one of claims 1 1 to 1 3 wherein the method further includes the step of attaching an insulation layer to the cushioning layer such that the sheets of material are attached to the cushioning layer via the insulation layer.

1 5. The method according to any one of claims 1 1 to 1 4 wherein the sheets of material are elongated strips adapted to attach to an end of a series of aligned springs.

1 6. A spring for use in an inner sprung cushioned article, wherein the spring is a coil spring having a cap at at least one terminal end of the spring, the face of the cap distal to the spring being substantially planar and lying in a plane substantially normal to the compression axis of the spring, the dimensions of the cap being such that the periphery of the cap extends beyond the periphery of the coil spring when viewed along the compression axis of the spring, and wherein the cap is formed of a flexible material having sufficient rigidity to maintain the substantially planar face.

SUBSTITUE SHEET (Rule 26)

7. The spring according to claim 1 6 wherein the cap is formed of a flexible material selected from reinforced webbing material, a spun polyester material, or a plastics material.

8. An inner sprung article substantially as herein described with particular reference to any one of the attached figures and related disclosure.

SUBSTITUE SHEET (Rule 26)