APPARATUS AND METHOD FOR MAKING A RESILIENT UNIT

Abstract

Apparatus for forming a resilient unit comprises a conveyor (210) and first and second spring supply stations (212 and 214), arranged in use to deposit respectively first and second spring types (216 and 218) under compression onto the conveyor. The conveyor is arranged in use to convey a row of the springs (216, 218) in a direction shown by Arrows A4 towards pocketing station (220). At the pocketing station (220) the springs are urged from the conveyor into positions between upper and lower sheets (222 and 224), by a plurality of inserter devices (226) that move together in a reciprocating fashion in the direction of arrow A5, before retracting to the position shown. After each row of springs is inserted between the sheets (222), upper and lower computer-controlled welding tools (not shown) come together at positions P between the springs to join the sheets together, forming pockets in which the springs are encased. After each welding event the resilient unit is indexed forwards a distance equal to one pocket width in the direction of Arrows A6 by computer-controlled drive means (not shown). The next row of springs is then conveyed into position ready for insertion between the sheets of material, and the process is repeated. The two spring supply stations are arranged to supply springs that differ from one another in at least one characteristic.

Claims

1. A resilient unit, comprising an array of first springs located in discrete pockets formed between superposed sheets of material joined at least at positions between the springs, wherein inside at least some of the first springs are located second, inner, non-pocketed springs.

2. The resilient unit according to claim 1, wherein the springs are held under compression in the pockets.

3. The resilient unit according to claim 1, wherein the second spring is taller/longer than the first spring.

4. The resilient unit according to claim 3, wherein the second spring is substantially held in position by the pocket of the first spring.

5. The resilient unit according to claim 1, wherein the first spring is wider than it is tall.

6. The resilient unit according to claim 1, wherein the second spring is taller than it is wide.

7. The resilient unit according to claim 1, wherein the first springs are of wire of a first gauge and the second springs are of wire of as second, different gauge.

8. The resilient unit according to claim 7, wherein the first gauge is greater, ie thicker, than the second gauge.

9. Apparatus for making a resilient unit, the apparatus comprising at least first and second resilient element supply stations, and a pocketing station, wherein the first and second resilient element supply stations are arranged to supply respectively at least first and second resilient element types to the pocketing station, which first and second types differ from one another in at least one characteristic, and wherein the pocketing station is arranged in use to insert the resilient elements between superposed sheets of material, and to encapsulate the resilient elements in pockets formed by joining the sheets at least at positions between the springs.

10. The apparatus according to claim 9, wherein the supply stations are arranged to supply the resilient elements to the pocketing station in at least one row.

11. The apparatus according to claim 9, wherein the resilient elements are supplied to the pocketing station in a row in which the first and second types of resilient element are offset with respect to each other.

12. The apparatus according to claim 9, wherein the resilient elements are supplied to the pocketing station in a compressed state, on a conveyor, which comprises one or more belts, or a belt and a compression plate.

13. The apparatus according to claim 9, wherein the resilient element types differ from one another according to at least one characteristic, of a list including but not limited to: material composition, stiffness or resilience, height, width, colour, and shape.

14. The apparatus according to claim 9, wherein there are three or more resilient element supply stations, arranged in use to supply respectively three or more resilient element types, which may differ from one another according to one or more characteristic.

15. The apparatus according to claim 9, wherein the resilient elements are arranged to be supplied to the pocketing station in a row comprising a plurality of discrete resilient element locations.

16. The apparatus according to claim 15, wherein the individual element locations may be occupied by a resilient element of a first type, or a resilient element of a second, third or successive type, or may not be occupied by a resilient element at all.

17. A method of making a resilient unit, the unit comprising an array of resilient elements in pockets formed between superposed sheets of material, the apparatus comprising: supplying at least first and second resilient element types from at least first and second supply stations to a pocketing station, which first and second types differ from one another in at least one characteristic, and inserting the resilient elements between superposed sheets of material at the pocketing station, to encapsulate the resilient elements in pockets formed by joining the sheets at least at positions between the springs.

18. The method according to claim 17, wherein the method comprises supplying the resilient elements to the pocketing station in at least one row.

19. The method according to claim 17, wherein the method comprises arranging resilient elements in the resilient unit such that one or more zones are formed, in which the resilient elements have different characteristics.

20. The method according to claim 17, wherein the method includes arranging resilient elements in the resilient unit such that a pattern is formed in the resilient unit, which pattern may provide a visual, aesthetic or structural effect.

21. A computer programme product on a computer readable medium, comprising instructions that, when executed by a computer, cause the computer to perform a method of making a resilient unit, the unit comprising an array of resilient elements in pockets formed between superposed sheets of material, the apparatus comprising: supplying at least first and second resilient element types from at least first and second supply stations to a pocketing station, which first and second types differ from one another in at least one characteristic, and inserting the resilient elements between superposed sheets of material at the pocketing station, to encapsulate the resilient elements in pockets formed by joining the sheets at least at positions between the springs.

22. A program for causing a device to perform a method of making a resilient unit, the unit comprising an array of resilient elements in pockets formed between superposed sheets of material, the apparatus comprising: supplying at least first and second resilient element types from at least first and second supply stations to a pocketing station, which first and second types differ from one another in at least one characteristic, and inserting the resilient elements between superposed sheets of material at the pocketing station, to encapsulate the resilient elements in pockets formed by joining the sheets at least at positions between the springs.

23. The resilient unit made by apparatus according to the method according to claim 17.

Description

[0036] A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which:

[0037] FIG. 1 shows in side schematic view a previously considered apparatus for forming a resilient unit;

[0038] FIG. 2 shows schematically an arrangement of spring supply stations and a pocketing station, according to an embodiment of the present invention;

[0039] FIGS. 3 to 7 show schematically examples of variants in the resilient unit made using the apparatus of FIGS. 1 and 2; and

[0040] FIGS. 8a and 8b show examples of alternative combinations of spring according to an embodiment of the present invention.

[0041] Turning to FIG. 2, this shows schematically at 200 apparatus for forming a resilient unit. The apparatus comprises a conveyor 210 and first and second spring supply stations 212 and 214, arranged in use to deposit respectively first and second spring types 216 and 218 under compression onto the conveyor. The conveyor is arranged in use to convey a row of the springs 216, 218 in a direction shown by Arrows A4 towards pocketing station 220. The conveyor may be according to any suitable design that allows the springs to be transported securely, preferably under compression. For example a pair of superposed belts or a single belt opposite a stationary plate can be used.

[0042] At the pocketing station 220 the springs are urged from the conveyor into positions between upper and lower sheets 222 and 224, by a plurality of inserter devices 226 that move together in a reciprocating fashion in the direction of arrow A5, before retracting to the position shown.

[0043] After each row of springs is inserted between the sheets 222, upper and lower computer-controlled welding tools (not shown) come together at positions P between the springs to join the sheets together, forming pockets in which the springs are encased. After each welding event the resilient unit is indexed forwards a distance equal to one pocket width in the direction of Arrows A6 by computer-controlled drive means (not shown). The next row of springs is then conveyed into position ready for insertion between the sheets of material, and the process is repeated.

[0044] The two spring supply stations are arranged to supply springs that differ from one another in at least one characteristic. In this case the springs 216 are of smaller diameter and are taller and stiffer than the springs 218. The result is a resilient unit in which alternate springs are taller and stiffer than their immediate neighbours. Because of its appearance this type of unit is sometimes referred to as a hi-lo unit.

[0045] FIGS. 3 to 7 depict some examples of the different patterns of resilient unit that can be obtained by using the apparatus of FIG. 2. In particular, using the twin supply stations, it is possible to make up a row for insertion in which each one of a plurality of defined spring locations is occupied either by a spring of a first kind, a spring of a second kind or else no springi.e. the absence of a spring (when one of the supply stations suspends its deposition of a spring for one cycle.

[0046] The example of FIG. 3 is one in which the a resilient unit 300 is made up of only one kind of spring, so that one supply station provides a spring of a certain kind in each location for each row.

[0047] FIG. 4 shows an example in which the resilient unit comprises a main portion 310 of a first kind, with a border of a second kind 320 of spring. The border may be made to have springs of a stiffer characteristic, for example.

[0048] FIG. 5 is an example in which the resilient unit is made up of alternating zones 330, 340 of different springs, providing a different characteristic, such as stiffness.

[0049] FIG. 6 uses a first kind of spring from one supply, combined with an absence of spring from the second supply, so that spaces appear to form a zig-zag visual pattern.

[0050] FIG. 7 shows a resilient unit 300 in which springs of one type are combined with absent springs, so as to reduce the density of springs in the unit 300.

[0051] It will be apparent to the reader that by using combinations of types of spring, or absences of spring, including springs that differ from one another in respect of one or more characteristics, it is possible to provide a resilient unit having a wide variety of patterns, both for aesthetic and functional purposes. Furthermore, the apparatus need not be confined to only two spring supply stations. With three or more supply stations the range of possibilities for more sophisticated patterns becomes still further extended.

[0052] The springs can differ from one another in respect of one or more characteristics such as from a list including but not limited to: stiffness, length, diameter, shape, colour and handednessie the direction of coil.

[0053] Furthermore, it is possible for a spring supply station to deposit more than one spring in the same location on the conveyor, for example by placing a pair of springs in a location, wherein one spring lies within the other, substantially coaxially.

[0054] Thus, in the assembled resilient unit, at least some of the pocketed springs may incorporate a second spring that is not encased in its own pocketi.e. is not itself independently pocketed.

[0055] FIGS. 8a and 8b show examples of a pair 400 of springs encapsulated within a pocket formed by two superposed sheets 222a and 222b of material, as described above. In each case the pair comprises an outer spring 410 and an inner spring 420. In FIG. 8a the outer spring 410 is taller than the inner spring. In FIG. 8b the inner spring 420 is taller, so that it protrudes slightly above the outer spring. Different spring combinations can provide finely tuned resilient characteristics. Ideally, the inner spring is at least as tall as the outer spring, and is more preferably taller than the outer spring.

[0056] In one preferred embodiment, the inner spring may be taller than it is widei.e. its length is greater than its maximum diameter. The outer spring may be shorter than it is widei.e. its height/length is less than its maximum diameter.

[0057] If the inner spring is taller than the outer one, as shown in FIG. 8b, and is held under compression in the pocket, its ends will press against, and be held by, the material or fabric of the pocket. This preferred arrangement means that the inner spring will be less likely to move within the pocket, and therefore less likely to contact the outer spring, which would result in unwanted noise.

[0058] Another measure that can be employed to minimize unwanted noise of springs rubbing against springs is to make the inner and outer springs have different handednessie for their directions of coil to be in an opposite sense, one left handed and one right handed, when viewed from an end. This also lessens the likelihood of the substantially coaxial springs meshing or jamming together.

[0059] The inner spring being taller than the outer one also affects the compression characteristic of the resilient unit, since the resistance to compression of the unit will come only from the inner spring in a first phase of compression, before further compression encounters resistance from the outer spring also. Such a dual tension micro-spring provides a so-called soft start compression characteristic, which is often desirable, for example in a mattress.

[0060] The inner and outer springs can be of different basic types, or shapes. For example, possible shapes for the springs include, but are not limited to, cylindrical, conical, barrel-shaped, and also hybrid types such as are described in our UK patent application no. 2495499.

[0061] The choice of gauge for the wire used in the springs is important. One of the springspreferably the inner springshould be of a smaller gauge, i.e. it should be of wire having a smaller average diameter.

[0062] This helps to reduce the potential for the pair of springs to make unwanted noise as they contact one another during compression or relaxation. The wire in at least one of the springs, and preferably both the inner and outer spring, should be less than or equal to 1.0 mm in diameter. In a preferred arrangement the wire of the inner spring should be of a diameter in the range 0.5 mm to 0.7 mm and the outer spring should be of wire having a diameter in the range 0.5 mm to 1.0 mm.

[0063] At least some adjacent springs, or pairs of springs within springs, in the array are preferably arranged to be of different handednessi.e. to be coiled in different directionsto combat any tendency for the resilient unit to become twisted due to the springs all being coiled in the same direction. Preferably the springs are arranged in alternate handedness.

[0064] Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the applicant claims protection in respect of any patentable feature or combination of features referred to herein, and/or shown in the drawings, whether or not particular emphasis has been placed thereon.