EP3925495A1

EP3925495A1 - Spring core with varied characteristic of corner springs

Info

Publication number: EP3925495A1
Application number: EP20180181.8A
Authority: EP
Inventors: Morten JØRGENSEN; Safet ZIZAK
Original assignee: L&P Swiss Holding GmbH
Current assignee: L&P Swiss Holding GmbH
Priority date: 2020-06-16
Filing date: 2020-06-16
Publication date: 2021-12-22
Anticipated expiration: 2040-06-16
Also published as: EP3925495C0; EP3925495B1

Abstract

A spring core (10) comprises a plurality of springs (21, 22) which are arranged in columns and rows. The plurality of springs comprises at least one corner spring (22). The corner spring (22) forms an end of one of the rows and an end of one of the columns. The at least one corner (22) spring differs with respect to at least one characteristic from a first adjacent group of the other springs (21) in the same row and a second adjacent group of the other springs (21) in the same column.

Description

FIELD OF THE INVENTION

The invention relates to a spring core, a box spring assembly, and a furniture product with a box spring assembly.

BACKGROUND

Spring cores are widely used in seating or bedding products. Such spring cores may be made from a matrix of multiple springs joined together directly such as by helical lacing wires, or indirectly such as by fabric within which each individual spring is contained. Pocket spring cores in which springs are respectively contained in a pocket of fabric are popular, due to the comfort and luxury feel provided by pocket spring cores.
In view of user comfort, it is known to provide spring cores with springs having different characteristics. For example, varying degrees of hardness may be achieved changing the gauge of the wire from which the springs are manufactured. The aim of such varied characteristics of the springs is to achieve tailored degrees of support in different zones of the spring core.
In some bedding products, the spring core may be used to form a box-spring. In this case, the spring core is typically mounted on a wooden frame, with a cover being stretched over the frame and the spring core, providing a rigid box-shaped structure with a flexible upper part. In such box-spring assemblies, the stretching of the cover material over the spring core may result cosmetic challenges. In particular, the stretch of the cover has the effect of the upper corners of the box-spring assembly being pulled diagonally inward, which may result in an undesirable degree of deviation from the desired box-like outer shape.
Accordingly, there is a need for spring core constructions which allow for efficiently avoiding undesired deviations in outer shape of a product formed from the spring core.

SUMMARY

According to an embodiment, a pocket spring core is provided, e.g., for incorporation into a bedding or seating product, in particular a box-spring bed. The spring core comprises a plurality of springs which are arranged in columns and rows. The plurality of springs comprises at least one corner spring. The corner spring forms an end of one of the rows and an end of one of the columns. The corner spring is thus arranged at a position where the row and the column meet each other, i.e., at a corner of the spring core. The at least one corner spring differs with respect to at least one characteristic from a first adjacent group of the other springs in the same row and a second adjacent group of the other springs in the same column. By means of the differing at least one characteristic, a product comprising the spring core can be efficiently tailored with respect to its appearance in the corner region, e.g., with the aim of providing a more or less pronounced corner sharpness.
According to an embodiment, the at least one corner spring has a different diameter than the springs of the first adjacent group and the springs of the second adjacent group. The at least one characteristic may thus correspond to or comprise the diameter of the corner spring. In some scenarios, the at least one corner spring has a larger diameter than the springs of the first adjacent group and the springs of the second adjacent group. In this way, support of a cover material in the corner region can be enhanced, which may allow for achieving a more pronounced corner sharpness, which is desirable in many products.
According to an embodiment, the at least one corner spring has a different number of coil turns than the springs of the first adjacent group and the springs of the second adjacent group. The at least one characteristic may thus correspond to or comprise the number of coil turns of the corner spring. In some scenarios, the at least one corner spring has a higher number of coil turns than the springs of the first adjacent group and the springs of the second adjacent group. In this way, support of a cover material in the corner region can be enhanced, which may allow for achieving a more pronounced corner sharpness, which is desirable in many products.
According to an embodiment, the spring core comprises multiple corner springs, each forming an end of one of the rows and an end of one of the columns at a different corner of the spring core. In this case, each of the corner springs may differ with respect to the at least one characteristic from a first adjacent group of the other springs in the same row and a second adjacent group of the other springs in the same column. In some scenarios, the corner springs can be provided at all corners of the spring core
Accordingly, the appearance of the product can be tailored at multiple or even all corner regions. In some scenarios, the corner springs differ with respect to the at least one characteristic from all other springs of the spring core.
According to an embodiment, the plurality of springs comprise at least first springs and second springs having different characteristics for forming different zones of the spring core. In this case, the at least one corner spring may differ with respect to the at least one characteristic from the first springs and from the second springs. For example, the first springs and the second springs could differ from each other with respect to wire gauge, and the at least one corner spring could differ from the first springs and the second springs with respect to diameter and/or number of coil turns.
According to an embodiment, the springs are each enclosed in a pocket of fabric material. Accordingly, the spring core may be formed as a pocket spring core. In such cases, the pocketed springs may form multiple strings corresponding to the rows or to the columns of the spring core, and the at least one corner spring may be arranged at a respective end of a respective one of the strings. Providing the corner springs may thus be efficiently integrated in the production process of the spring core.
According to an embodiment, a box-spring assembly is provided, which comprises the above-mentioned spring core. In addition, the box-spring assembly may comprise a framework for supporting the spring core and a cover stretched over the spring core.
According to an embodiment, a bedding or seating product is provided, which comprises the above-mentioned box-sprig assembly. The bedding or seating product may for example correspond to a box-spring bed.
According to an embodiment, a method of manufacturing the above-mentioned spring core is provided. The method comprises providing the plurality of springs. Further, the method comprises joining the strings to form the spring core. In some scenarios, the method may further comprise forming strings of the springs and providing the at least one corner spring at an end of at least one of the strings. The method may be performed in an automated manner, e.g., by using a spring coiling machine for providing the springs, by using a spring pocketing machine to form strings of pocketed springs, and/or by using an assembly machine to join the strings to form the spring core.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described with reference to the accompanying drawings.

FIG. 1 is partial sectional view of a box-spring assembly according to an embodiment.
FIG. 2 illustrates an example arrangement of spring elements in a spring core according to an embodiment.
FIG. 3 illustrates a further example arrangement of spring elements in a spring core according to an embodiment.
FIG. 4 shows a flowchart for schematically illustrating an embodiment according to an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Exemplary embodiments of the invention will be described with reference to the drawings. While some embodiments will be described in the context of specific fields of application, such as in the context mattresses, the embodiments are not limited to this field of application. The features of the various embodiments may be combined with each other unless specifically stated otherwise. Throughout the following description, same or like reference numerals refer to same or like components or mechanisms.
FIG. 1 schematically illustrates a box-spring assembly 100 according to an embodiment. In particular, FIG. 1 shows a partial sectional view of a corner region of the box-spring assembly 100. Here, it is to be understood that the box-spring assembly may have a substantially rectangular shape with four corners that each have a configuration as illustrated in FIG. 1.
As illustrated, the box-spring assembly 100 comprises a spring core 10 formed of a plurality of springs 21, 22, in particular coil springs. In the illustrated example, the spring core 10 is formed as a pocket spring core, with each spring 21, 22 being enclosed in a pocket 20 of fabric material. For example, the spring core 10 may be formed of multiple strings of pocket spring elements. The strings may respectively be formed by providing a fabric layer, inserting a spring 21, 22 into the fabric layer, folding the fabric layer so as to cover the spring either before or after insertion of the spring, and applying longitudinal and transverse seams, e.g. by welding. Each string may extend across the full width of the spring core. The strings may be connected in side-by-side relationship as, for example, by gluing the sides of the strings together, so as to create an array or matrix of springs 21, 22 having multiple rows and columns of springs 21, 22 connected to each other. As a result, the spring core 10 forms a unitary structure having a width W and length L. In the following, it will be assumed that the rows are arranged along the width direction and the columns are arranged along the length direction. However, it is noted that it would also be possible that the rows are arranged along the length direction and the columns are arranged along the width direction. It is noted that the implementation as a pocket spring core is only one example, and that in other examples the spring core 10 could also be formed by using a wire framework for connecting the springs 21, 22 to each other.
FIG. 2 shows a top view for schematically illustrating an example of arranging the springs 21, 22 in rows and columns. As can be seen from FIG. 2, two outer rows of the springs 21, 22 and two outer columns of the springs 21, 22 form side edges of the spring core 10. Corners of the spring core 10 correspond to positions where respective pairs of the side edges meet.
The sectional view of FIG. 1 is assumed to be taken along broken line A in FIG. 1, i.e., at the upper right corner of the spring core 10, along the width direction. However, it is to be noted that similar sectional views as illustrated in FIG. 1 could also be provided for the other corners of the spring core and along the width direction.
As further shown in FIG. 1, the box spring assembly 100 includes a frame 31 and slats 32 on which the spring core 10 is supported. For example, the frame 31 and the slats 32 may be of wood, and the spring core 10 may be mounted on the frame 31 and the slats 32 by stapling or the like. As further illustrated, a cushioning layer 41, e.g., in the form of a foam plate, may be provided on a top surface of the spring core 10. Further, a cover 42, e.g., formed of a textile fabric, is stretched over the frame 31, the spring core 10 and, if present, the cushioning layer 41, to form a uniform outer surface of the box-spring assembly 100.
As shown in FIGS. 1 and 2, the springs 21 and 22 of the spring core 10 have different characteristics. In particular, the springs 22, which are arranged in the corners of the spring core 10 and may therefore also be referred to as corner springs, differ from the other springs 21 of the spring core 10. In particular, the corner springs 22 differ from the other springs 21 forming the side edges of the spring core 10. As mentioned above, a corner of the spring unit 10 is assumed to be a position where two lateral edges of the spring unit 100 meet. A corner spring 21 may also be defined as a spring which is located both at an end of a row and at an end of a column.
In the illustrated example, the corner springs 22 and the other springs 21 differ with respect to a diameter of the springs 21, 22 and with respect to a number of turns of the springs 21, 22. In particular, the corner springs 22 have a larger diameter than the other springs 21 and a higher number of turns than the other springs 21. In this way, it can be achieved that the stretching of the cover 42 over the spring core 10 causes an undesirable rounding of the corners of the box spring assembly 100. In other words, it can be achieved that the corners of the box spring assembly 100 closely conform to a cosmetically desirable shape of a "sharp corner", in FIGS. 1 and 2 schematically indicated by dotted lines S. In the example of FIGS. 1 and 2, the springs 21 have a first diameter D1, and the corner springs 22 have a second diameter D2, which is larger than the first diameter D1. Further, the springs 21 have a first number of turns N1, and the corner springs 22 have a second number of turns N2, which is higher than the first diameter D1. By way of example, D2 may be by 10% to 20% larger than D1, and N2 may be by 10% to 20% higher than N1.
In the example of FIG. 2, it was assumed that the spring core 10 is formed of only two types of springs 21, 22, i.e., with one type corresponding to the corner springs 22 and the other corresponding to the other springs 21. However, it is noted that the illustrated concepts could also be combined with other variations of characteristics of the springs 21, 22 forming the spring core. FIG. 3 schematically illustrates a corresponding example of a spring core 10'.
In the example of FIG. 3, the spring core 10' includes multiple zones 11, 12, 13, 14, 15 which are formed of different types of springs 22, 23 to conform to variations in the degree of support required for comfort of a user. In the illustrated example, the zone 11 is a head zone which in typical usage scenarios would support the head of a user, the zone 12 is a shoulder zone which in typical usage scenarios would support the shoulders or upper body of the user, the zone 13 is a middle zone which in typical usage scenarios would support the lower body or pelvis of the user, the zone 14 is a leg zone which in typical usage scenarios would support the upper legs or knees of the user, and the zone 15 is a feet zone which in typical usage scenarios would support the feet of the user. In the illustrated example, the spring core 10' has a symmetrical configuration in which the section 11 is similar to the section 15 and the section 12 is similar to the section 15. Accordingly, the spring core assembly could also be used for the opposite orientation of the user, i.e., with the head at the section 15. However, it is noted that also configurations could be used where the zones 11, 12, 13, 14, 15 each have a different configuration.
In the example of FIG. 3, the zones 11 and 15 are formed of a first type of springs 21 and of the corner springs 22. The zone 13, which has no corners, is formed of only the first type of springs 21. The zones 12 and 14 are formed of a second type of springs 23, which has other characteristics than the first type of springs 21 and the corner springs 22. In the illustrated example, the second type of springs 23 is assumed to have a softer characteristic than the first type of springs 21, e.g., by forming the spring of a wire with different gauge. In this way, the zones 12 and 14 may be provided with more elasticity than the zones 11, 13, and 15, so that the shoulders and upper legs of the user can be supported in a comfortable manner.
As can be seen from the example of FIG. 3, in some scenarios further variations of spring characteristics may be present in the spring core 10, 10', in addition to providing the corner springs 22 with a different diameter and different number of turns. Also in such cases, the corner springs 22 differ from the other springs of the rows and columns forming the side edges.
Further, it is noted that in the examples of Figs. 1, 2, and 3 the four corner springs 22 were assumed to have the same characteristics. Accordingly, the rows forming the width-wise side edges each include two corner springs 22 having the same characteristics. Nonetheless, these differ from a respective adjacent group of springs of the same row. Similarly, the columns forming the length-wise side edges each include two corner springs 22 having the same characteristics. Again, these differ from a respective adjacent group of springs of the same column.
Fig. 4 shows a flowchart for illustrating a spring core manufacturing process which may be used to manufacture a spring core as described above, e.g., the spring core 10, 10'. That is to say, the method may be used to manufacture a spring core including at least one corner spring differing with respect to at least one characteristic from adjacent springs of the corner spring. As mentioned above, this at least one characteristic may correspond to or include a diameter of the spring and/or a number of turns of the spring.
At step 410, a plurality of springs is provided. The springs include the at least one corner spring and other springs. The at least one corner spring differs with respect to the at least one characteristic from the other springs. The springs may be provided by a coil winding machine.
At step 420, strings may be formed from the springs provided at step 410. The strings may be formed as strings of pocketed coil springs, e.g., as illustrated in the example of FIG. 1.
At step 430, at least one of the strings may be provided, at at least one end of the string, with a corner spring having a different characteristic than one or more other springs adjacent to the corner spring. In typical scenarios, the string may have a first corner spring at the first end of the string and a second corner spring at the second end of the string. Further, in typical scenarios two of the strings are each provided with first corner spring at the first end of the string and a second corner spring at the second end of the string. In this way, two of the strings may each be provided with two corner springs, resulting in a total of four corner springs which are to be arranged at four different corners of the spring core. However, it is noted that in some scenarios, less than four corners of the spring core could be provided with the corner spring having different characteristics. In this case, the corner spring could be provided at only one end of the string and/or only one of the strings could be provided with the corner spring(s).
Steps 420 and 430 may be performed in a continuous process by a spring pocketing machine supporting mixing of different spring types in the same string.
At step 440, the strings are joined to form the spring core, with the corner spring(s) each being arranged at a respective corner of the spring core. This may for example involve joining the strings by gluing, welding, or some other assembly process. For this purpose, a correspondingly configured assembly machine may be utilized.
It is noted that the embodiments and examples described above are susceptible to various modifications. For example, the corner spring(s) having different characteristics may be combined with various other variations of spring characteristics in the spring core. For example, a more complex zoning than in the example of FIG. 3 could be provided by using one or more additional spring types on the edges and/or in the interior of the spring core. Further, a wide variety of coil springs or other types of springs, e.g., foam springs, could be used. Further, when using coil springs, it is noted that these may have a cylindrical shape, but could also be hourglass shaped, barrel shaped, or cone shaped. Still further, the dimensions of the springs may be selected in various ways. Moreover, it is noted that the illustrated concepts may be applied for other purposes than for increasing corner sharpness of a product. For example, the characteristic of the corner spring could also be used for providing a more rounded corner appearance, if desired, by using corner springs having a smaller diameter than the other springs.
Further, while the examples explained the spring core is part of a box-spring assembly, in particular a box-spring bed, it is noted that the same or similar spring cores could also be used in various other kinds of bedding or seating products, such as in sofas or seats, e.g., as part of a sofa cushion or seat cushion.

Claims

A spring core (10; 10'), comprising:
a plurality of springs (21, 22, 23) arranged in columns and rows,

wherein the plurality of springs (21, 22, 23) comprises at least one corner spring (22), which forms an end of one of the rows and an end of one of the columns,

wherein the at least one corner spring (22) differs with respect to at least one characteristic from a first adjacent group of the other springs (21) in the same row and a second adjacent group of the other springs (21, 23) in the same column.
The spring core (10; 10') according to claim 1,
wherein the at least one corner spring (22) has a different diameter than the springs (21, 23) of the first adjacent group and the springs (21, 23) of the second adjacent group.
The spring core (10; 10') according to claim 2,
wherein the at least one corner spring (22) has a larger diameter than the springs (21, 23) of the first adjacent group and the springs (21, 23) of the second adjacent group.
The spring core (10; 10') according to any one of the preceding claims,
wherein the at least one corner spring (22) has a different number of coil turns than the springs (21, 23) of the first adjacent group and the springs (21, 23) of the second adjacent group.
The spring core (10; 10') according to claim 4,
wherein the at least one corner spring (22) has a higher number of coil turns than the springs (21, 23) of the first adjacent group and the springs (21, 23) of the second adjacent group.
The spring core (10; 10') according to any one of the preceding claims, comprising:
multiple corner springs (22), each forming an end of one of the rows and an end of one of the columns at a different corner of the spring core (10; 10'),

wherein each of the corner springs (22) differs with respect to the at least one characteristic from a first adjacent group of the other springs (21) in the same row and a second adjacent group of the other springs (21, 23) in the same column.
The spring core (10; 10') according to claim 6,
wherein the corner springs (22) differ with respect to the at least one characteristic from all other springs (21, 23) of the spring core (10; 10').
The spring core (10; 10') according to claim 6 or 7,
wherein the corner springs (22) are provided at all corners of the spring core (10; 10').
The spring core (10') according to any one of the preceding claims,
wherein the plurality of springs (21, 22, 23) comprise at least first springs (21) and second springs (23) having different characteristics for forming different zones (11, 12, 13, 14, 15) of the spring core (10'), and
wherein the at least one corner spring (22) differs with respect to the at least one characteristic from the first springs (21) and from the second springs (23).
The spring core (10; 10') according to any one of the preceding claims,
wherein the springs (21, 22, 23) are each enclosed in a pocket (20) of fabric material.
The spring core (10; 10') according to claim 10,
wherein the pocketed springs (21, 22, 23) form multiple strings corresponding to the rows or to the columns, and
wherein the at least one corner spring (21, 22, 23) is arranged at a respective end of a respective one of the strings.
A box-spring assembly (100), comprising:
a spring core (10; 10') according to any one of the preceding claims,

a framework (31, 32) for supporting the spring core (10, 10'); and

a cover (42) stretched over the spring core (10, 10').
A bedding or seating product comprising a box-spring assembly (100) according to claim 12.
A method of manufacturing a spring core (10, 10') according to any one of claims 1 to 11, the method comprising:
- providing the plurality of springs (21, 22, 23);

- joining the strings to form the spring core (10; 10').
The method according to claim 14, comprising:
- forming strings of the springs (21, 22, 23); and

- providing the at least one corner spring (22) at an end of at least one of the strings.