Foam layer and foam strip for forming a foam spring and a method for manufacturing a foam spring

ES 2 397 520 T3

DESCRIPTION

Improved foam spring for pillows, cushions, mattresses or the like and method of manufacturing said foam spring

Field of the invention

[0001] The present invention relates to an improved foam spring, in particular to an improved foam spring with an elastic tubular body made of foam with holes extending inward from the outside and which can be applied to the inside of pillows, mattresses, chair cushions or the like.

[0002] The invention also relates to a method for the manufacture of such an improved foam spring.

Background of the invention

[0003] Foam springs are known for example from the European patent publication EP 0 001 469, which shows an elastic spring element and a method for producing the same, characterized in that it mainly consists of a tubular body , made of synthetic or similar porous material, whereby the body wall shows several holes in stepped symmetry, whose cross-sectional surface varies from practically zero on the inner wall of the body to a maximum value on the outer wall, no load being applied.

[0004] To establish the desired resilience of the spring, it is shown that at least one core of flexible elastic material is mounted on the aforementioned tubular body, whereby the diameter of the former mainly corresponds to the internal diameter of the tubular body.

[0005] It is also known from the European patent publication EP 0 624 332 a flexible elastic element comprising a tubular foam body having holes extending inward from the outside, characterized in that it comprises a wire spring which is surrounded by the body.

[0006] Unlike a flexible elastic material consisting only of foam, it is claimed that no loss of hardness occurs with a fatigue test when normal and therefore cheaper types of foam are used for the construction of the tubular body. .

[0007] A method for manufacturing an elastic tubular body for pillows, mattresses and the like is also known in the art of published US patent application 2005/0172468, said method consisting of providing grooves in a foam layer , in the cutting of a band of this foam layer; in the folding of these two opposite ends of the band against each other; and in fixing these two opposite extremities to form the elastic tubular body, whereby the foam layer is made of what is called a viscoelastic foam, and whereby at least a part of the cells present in the foam are broken open.

[0008] The tubular body formed in this way receives here preferably has an external biconical or almost biconical shape.

[0009] It is claimed that, unlike common elastic flexible foam bodies made of foam with a low relative density, such as the elastic tubular body does not lose its resilience in a short period of time of actual use, as a result of which is capable of maintaining its functionality for a longer period of time when applied to pillows or the like.

[0010] Also known in the art, as disclosed in the European patent publication EP 0 872 198, foam springs comprising a tubular body of foam that is provided on its walls with cavities that are directed inwards from the outside, characterized by the fact that the body is widening-narrowing from one end to the other, resulting in a barrel-shaped outer shape, that is, in case the body has a round configuration to begin with.

[0011] As a main advantage of these springs it is claimed that, unlike common embodiments, they fatigue less easily and do not lose their initial height and shape after a short useful life time.

Foam springs are also known from published PCT international application WO 2009/036524 for use in pillows, mattresses or the like, having an elastic tubular body made of foam, with holes extending inwards from the outer surface towards an inner surface, wherein the tubular body comprises at least one tubular foam layer and at least one reinforcing layer applied to said foam layer over at least a part of the axial length of the spring.

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[0013] It is claimed that the elastic behavior of said spring can be easily adapted by means of a reinforcing layer with a different extension resistance.

[0014] Although such known foam springs are highly valued by users of pillows, mattresses or the like, they have the disadvantage that the exterior of the spring must be given a particular shape, thus making packaging of the springs more difficult. a dose and dense of the springs next to each other, or that additional components such as wire springs or reinforcing cores or special reinforcements or reinforcing layers must be provided, which makes the manufacture of such springs more complicated, more expensive, more energy consuming and more polluting for the environment.

[0015] They also have the disadvantage that they are easily damaged, for example during manufacturing, packaging, storage, transportation, installation etc. or when assembling pillows, mattresses or the like, due to the high extension forces applied to the springs.

Therefore, the handling of said springs needs to be carried out with some caution, which implies special care, often resulting in a slower production process and higher production costs.

[0017] Another drawback of the known springs is that, when compressed in the axial direction, they tend to show protrusions in the lateral direction, thus influencing the behavior of the adjacent springs.

[0018] Therefore the elastic behavior of the individual springs of a pillow, mattress or the like is sometimes difficult to predict so accommodating a pillow, mattress or similar to the needs or body shape of the user is not an easy task. .

[0019] A foam spring is also known from WO 25/2761 A1.

Summary of the invention

[0020] An object of the present invention is to provide a foam spring with improved properties for use in pillows, cushions, mattresses or the like, which does not have any of the aforementioned or other disadvantages.

To this end, the invention relates to a foam spring for use in pillows, cushions, mattresses or the like, the foam spring with an elastic tubular body made of foam and forming an external wall, with holes extending towards the interior from an exterior surface towards an interior surface, said holes being arranged in a staggered symmetry and mainly in the shape of a rhombus, characterized in that the tubular body shows said holes only on a limited part of its surface, and that this limited part is uniformly alternated with a limited part of the surface that does not have said holes and that forms ribs of longitudinal reinforcements in the wall of the tubular body of the spring.

[0022] A main advantage is that, together with their uniform spacing in the tubular body of the spring, the reinforcing ribs allow a greatly improved distribution of the compression forces when the spring is under load, no longer requiring the incorporation of a spring metallic or additional reinforcements or the use of foam layers of different density, or the like, as taught in the prior art.

[0023] Additionally, the reinforcing ribs formed in accordance with the invention prevent the foam from forming further bulges out of the lateral pathways when compressed under load, even when a lower density foam is used to form the body.

[0024] The use of a foam of lower density, without loss of the main static and dynamic properties of the spring, not only reduces the cost of raw materials and energy consumption while providing important gains in production time, but which also gives a better feeling of comfort and adaptability of the foam to the shape of the body when used in mattresses, pillows, cushions or the like, which is often highly appreciated and valued by the end user.

[0025] A comparable or even better static, dynamic and long-term spring behavior can be achieved in a much simpler and less expensive way than with springs according to the prior art.

[0026] A main advantage is that the reinforcing ribs form an integral part of the tubular body and are produced in one and the same production step, not creating problems of adhesion, lamination, assembly, storage and obtaining of individual components, etc.

[0027] Another advantage is that, as a result of this, the springs are less prone to damage from rough handling during the manufacture and assembly of a pillow, mattress or the like.

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Therefore less care must be taken not to damage the springs during production, assembly, handling, storage, installation, etc., which invariably results in higher production speeds and a reduction in rates. total rejection.

The longitudinal reinforcing ribs created according to the invention will in turn prevent the elastic properties of the springs from being less affected by adjacent compressed springs, making the elastic behavior of each individual spring more predictable when used in a pillow, mattress or similar.

Due to this more predictable behavior of the springs, it is easier to tailor a pillow, mattress or the like with respect to a particular preference of the user or his body shape and weight to give the user a great feeling of comfort.

Another advantage of the springs according to the invention is that, due to the creation of evenly spaced reinforcing ribs and the absence of other constructive elements, such as wire springs, in the tubular wall, the springs are more resistant against rough handling damage during the manufacture and assembly of the pillow, mattress or similar, and considerably reduce its weight and complexity.

Another advantage is that the elastic behavior of the spring according to the invention can be easily adjusted not only by a judicious choice of raw materials and the foam made from them, but also by the relative proportion of the parts that are provided with holes. and of those that are not and because of their geometric arrangement and relative distribution along the body of the spring.

These foam springs according to the invention can, of course, be combined with other types of springs to create different comfort zones with different softness in a pillow, mattress or the like.

According to a preferred embodiment, the part of the body that is not provided with holes and therefore forms a plurality of reinforcing ribs extends from the lower part to the upper part of the tubular body.

According to another preferred embodiment, the width of the part provided with holes is essentially equal to the width of the part not provided with said holes, determined in the unextended foam.

According to another preferred embodiment the holes are not only staggered with respect to each other, but also with respect to the holes formed in any adjacent part that is separated from these parts by a part that is not provided with said holes.

According to another preferred embodiment, the outer surface of the part that is not provided with holes shows a sinus shape over a part or over the total axial length of the spring.

According to another preferred embodiment, the non-perforated parts form a plurality of reinforcing ribs uniformly spaced along the periphery of the tubular body and along its longitudinal axis.

According to another preferred embodiment, the number of parts that are not provided with holes and form reinforcing ribs is between 4 and 12, preferably between 6 and 10, more preferably equal to 8.

According to another preferred embodiment the spring comprises a band with at least one layer of foam and a series of grooves extending in one direction and surrounded by corresponding areas that do not contain grooves, and two opposite ends extending in the direction of the grooves. grooves, the opposite ends of the band being curved to approximate each other and glued together to form said hollow tubular body and to form said diamond-shaped holes by stretching the grooves in the transverse direction due to the folding of the band, and to convert the areas not grooved in regularly spaced reinforcing ribs along the periphery of the tubular body and aligned along its longitudinal axis.

According to another preferred embodiment the grooves of the band extend along a plurality of interrupted parallel lines.

[0042] According to another preferred embodiment the web grooves are positioned in a staggered pattern, where the grooves along adjacent lines are offset in their longitudinal direction.

[0043] According to a preferred embodiment the grooves of the strip between two adjacent areas that are separated by a grooved area, are positioned according to a staggered pattern, where the grooves along adjacent lines are displaced in their longitudinal direction.

The invention also relates to a method for manufacturing a foam spring with an elastic tubular body for use in pillows, mattresses or the like, this method comprises providing interrupted grooves along lines extending in the longitudinal direction of at least a part of a foam layer and alternating said grooves in a regular pattern with an adjacent part of the foam layer not provided with said 4

ES 2 397 520 T3 grooves, cut a transverse band of this foam, fold two opposite ends of the band towards each other;

and fixing the two opposite ends in a tubular shape to form the elastic tubular body, wherein on the outside and along the longitudinal axis of the tubular body, the slotted parts and the adjacent non-slotted parts are regularly alternating, and in which the latter form solid longitudinal reinforcing ribs in the tubular body of the spring.

Brief description of the drawings

[0045] To better explain the characteristics of the invention, the following preferred embodiment of a foam spring and of a method according to the invention for the manufacture of said foam spring is described only as an example, without being limiting of any way, with reference to the attached drawings, in which:

Figure 1 represents a schematic perspective view of a foam spring according to the invention;

[0047] Figure 2 represents a foam layer with evenly spaced areas containing slits, alternating with areas that do not contain any slits, used to manufacture a foam spring according to the invention.

Description of the preferred embodiment

[0048] The spring represented in figure 1 is a foam spring 1 for use in pillows, cushions, mattresses or the like and comprises an elastic tubular body 2 with holes 3 extending inwards from the outer surface 4 towards the inner surface 5 of dock 1.

The tubular body 2 further comprises a foam layer 6.

The holes 3 are here preferably arranged in a staggered and regular pattern with respect to each other.

This allows any deformation of the spring 1 under compression along the direction represented by the arrow P to be distributed evenly throughout the body of the spring 1, thus limiting any radial bulging out of the spring 1 and preventing the Compressive forces are concentrated only in a part of the spring 1 instead of being uniformly distributed throughout the body 2 of the spring 1.

The areas 16 (represented in figure 2) that contain said holes 3 alternate with areas 18 (represented in figure 2) that do not contain any holes 3, these forming reinforcing ribs 7 that are uniformly distributed along from the periphery of the tubular body 2.

[0053] In a preferred embodiment, the shape of the reinforcing ribs 7 is a sine wave or follows a continuous Z or S-shaped line in the longitudinal direction X-X ', as represented by the dotted line 14.

[0054] An advantage of a foam spring 1 as represented in figure 1 is that, when the spring is compressed in the axial direction XX 'as represented by the arrow P, the foam spring 1 does not have a tendency to bulge in a lateral or radial direction and that therefore the diameter of the tubular spring is essentially conserved.

[0055] Another advantage of this preferred embodiment is that the resilience, compression force, and the useful life of the spring 1 according to the invention are remarkably improved, even when lower density foam is used for its construction.

Figure 2 represents a foam layer 6 from which, according to the invention, the foam spring 1 is made.

[0057] The method for forming the foam spring 1 is relatively simple and comprises the following steps:

In a first phase a rectangular band 8 is cut from a suitable foam layer 6 with an axis of symmetry XX 'and with two pairs of parallel side walls 9-10 and 11-12 respectively.

In the band 8, areas 16 are provided with grooves 17, according to a direction parallel to the aforementioned axis of symmetry X-X ', and alternating, in a regular pattern, with areas 18 without grooves 17.

[0060] The grooves 17 of the band 8 are cut along a plurality of interrupted parallel lines 13 at an equal distance from each other.

The grooves 17 are advantageously located in a stepped pattern, whereby the grooves 17 along adjacent lines 13 move in their longitudinal direction X-X ', for example by a distance equal to half the length longitudinal grooves 17.

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[0062] To form the tubular body 2 of the foam spring 1, the band 8 is curved in the way that is schematically represented by means of the dotted lines 15.

In this way, the side walls 11 and 12 come together and are in a next step solidly fixed to each other, for example by gluing, thus forming the tubular body 2 of the foam spring 1.

As a result of the aforementioned folding the band 8 is extended and the slots 17 open to form the aforementioned holes 3, which extend radially through the body 2 and alternate with reinforcing ribs 7 created by the surrounding areas 18 which do not contain grooves, and therefore will not show holes 3 when the tubular body 2 is formed at a later stage.

[0065] In the case that several rows 13 of grooves 17 are arranged in the staggered configuration not only compared to each other, but also compared to the grooves 17 of the next area 16 separated by an area 18 containing no grooves 17 , the reinforcing ribs 7 thus formed at a later stage and represented in figure 1, obtain a wave or sine shape, represented by the dotted line 14 in figure 1.

This wave or sine shape of the reinforcing ribs 7 according to the invention is especially suitable for converting any deflection of the spring 1 under compression in the direction of the arrow represented by P, into a tangential deformation of the reinforcing ribs shaped like a sine 7, which prevents the spring 1 from bulging radially, with all the negative consequences that this entails, as explained above.

Although according to a preferred embodiment of the invention the reinforcing ribs 7 extend over the total axial length L of the spring 1, it is not excluded that the reinforcing ribs 7 only extend over a part of said length L axial.

The invention is not necessarily limited to cylindrical springs 1, it can also be applied to other forms of springs.

The present invention is in no way limited to the above-described embodiments and manufacturing method given as an example and represented in the accompanying drawings; on the contrary, the foam spring and the method for manufacturing said spring can be varied while remaining within the scope of the invention, according to the appended claims.