Method and apparatus for making a resilient unit

Abstract

A method of making a resilient unit comprises arranging integral pocketed resilient elements in clusters, wherein each integral pocketed resilient element in a cluster is attached to at least one other integral resilient element, and wherein the clusters define spaces or interstices, and inserting an independent resilient element into one or more of the spaces or interstices The independent spring (260) is, in this example, a pocketed coil spring of an axial length slightly shorter than the springs (110) (only one of which is shown) making up the cluster (240), and of a smaller diameter. The length and diameter of the independent spring (260) may be different, according to the required characteristic of the resilient unit as a whole. In order to insert the independent spring (260), an inserter device (270), is first placed substantially vertically above the interstice. The device (270) comprises a hollow inserter tube (270a) with a frusto-conical funnel portion (270b) at its upper end, and an inner guide pole (270c), with a dome-shaped (alternatively conical) leading end (270d) projecting slightly beyond the end of the tube (270a). The tube (270a) and guide pole (270c) are almost the same diameter, with the latter being a close fit within the former. To insert the independent spring into the cluster, the device (270) is first inserted into the interstice (250), both pole (270c) and tube (270) together, with the dome-shaped leading end (270d) of the pole helping to ease the way past the coils of adjacent springs in the cluster.

Description

[0001] Method and Apparatus for Making a Resilient Unit

[0002] The present invention relates to a method of manufacture of a resilient unit such as may be used in a mattress for example , and more particularly one that may be customised .

[0003] Mattress cores are typically formed from coil springs encased in pockets . Referring to Figure 1 , the springs 10 are initially placed between sheets or plies of pocketing material , which could be a single sheet 20 folded into two . The sheets are then glued, stitched or welded along their edges and between the springs to encase the springs in individual pockets . Figures 2 and 3 are respective schematic side and perspective views of a so-called " string" 30 of springs formed in this way .

[0004] The strings 30 are then glued together along the cylindrical surfaces of the pocketed springs to form an array 40 as shown in Figure 4 . Such an array, of an appropriate length and width, is used as a mattress core .

[0005] Glue is expensive and cannot easi ly be recycled, so in recent times ef forts have been made to find alternative means of holding the strings together . However, thus far, many such alternatives have either proved inflexible or expensive to manufacture , or both .

[0006] Furthermore , it may be desirable to be able to create variations in the appearance or resilient characteristics of a mattress readily during its manufacture . Embodiments of the present invention aim to provide a method of manufacturing a resilient unit suitable for a mattress , which unit may have at least one characteri stic changed, or customised, whilst using little or no glue , thereby allowing it to be readily recycled .

[0007] The present invention is defined in the attached independent claims , to which reference should now be made . Further, preferred features may be found in the sub-claims appended thereto .

[0008] According to one aspect of the present invention, there is provided a method of making a resil ient unit comprising arranging integral pocketed resil ient elements in clusters , wherein each integral pocketed resilient element in a cluster is attached to at least one other integral resilient element , and wherein the clusters define spaces or interstices , and inserting an independent resilient element into one or more of the spaces or interstices , wherein the method comprises placing a hollow inserter tube into the interstice and introducing the independent resilient element to the unit through the hollow inserter tube , and wherein the inserter tube is placed into the resil ient unit with a guide member located coaxially with and inside the hollow tube .

[0009] The integral resilient elements and / or the independent resilient elements may comprise coil springs .

[0010] The clusters may comprise at least two , and preferably more than two integral or j oined pocketed springs . The guide member and inserter tube may be inserted into the resilient unit together . Alternatively, the guide member may be inserted into the resilient unit and then the inserter tube may be slid over the guide member .

[0011] In a preferred arrangement , the guide member is arranged to proj ect beyond the leading end of the inserter tube .

[0012] The guide member may have a leading end which may comprise a dome-shaped or conical portion, to easily allow the guide member to penetrate the interstice .

[0013] The guide member may comprise a rod or tube .

[0014] The guide member is preferably arranged to be a close , coaxial fit within the inserter tube .

[0015] Preferably, the method comprises inserting the guide member and inserter tube into the interstice , then withdrawing the guide member, before the independent resilient element is introduced to the interior of the inserter tube .

[0016] The independent resilient element may be introduced to the interior of the inserter tube through an open axial end of the tube . Alternatively, the independent resilient element may be introduced to the interior of the inserter tube through an aperture in a side wall of the tube .

[0017] The independent resilient element may be introduced into the interior of the inserter tube under compression . In another aspect , the present invention provides apparatus for inserting an independent resilient element into an interstice or space formed by a cluster of integral pocketed resilient elements , at least some of which are j oined to one another, the apparatus compri sing a guide member and a hollow inserter tube for receiving an independent resilient element , and wherein the guide member has a dome-shaped or conical leading end, and is arranged to fit closely within the inserter tube , and wherein, when so inserted, the leading end of the guide member is arranged to proj ect beyond the inserter tube to enable the inserter tube to easi ly penetrate the interstice .

[0018] The inserter tube may include an aperture for introducing an independent resilient element into the tube . The aperture may be an axial end aperture . Alternatively or in addition the aperture may be located in a side wall of the tube .

[0019] The invention may include any combination of the features or limitations referred to herein, except such a combination of features as are mutually exclus ive , or mutually inconsistent .

[0020] 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 :

[0021] Figures 1-3 show some pocketed springs in a string, at di f ferent stages of manufacture , according to a previously considered structure ; Figure 4 shows in schematic perspective view a plurality of strings j oined together to form a resilient core unit according to a previously considered structure ;

[0022] Figure 5 shows , in schematic plan view, two strings of pocketed springs in an early stage of manufacture of a resilient core unit according to an embodiment of the present invention;

[0023] Figures 6 and 7 show schematically further method steps for producing the resilient core unit of Figure 5 ;

[0024] Figures 8 and 9 are schematic plan views of the resilient core unit of Figures 5-7 further, later stages of manufacture ;

[0025] Figures 10 - 14 show schematically stages in a method of inserting an independent spring into a resilient core , according to an embodiment of the present invention; and

[0026] Figure 15 shows schematically an alternative method for inserting the spring .

[0027] Turning to Figure 5 , this shows two single strings 130 of pocketed springs , each comprising a linear array of metal , e . g . steel , coil springs 110 encased in individual pockets formed by sheets 120 of weldable pocketing material , which may, for example , comprise spun-bonded polymer, e . g . polyester or polypropylene . It should be noted that the strings shown as examples contain only six individual pocketed springs, whereas in reality they would include more than this, depending upon the desired dimensions of the resilient core unit being manufactured.

[0028] The sheets 120 (which may comprise a single sheet that has been folded over the springs or may comprise two separate sheets) are joined along their edges (not shown) , in this example by ultrasonic welds. The sheets are also joined between the springs 110, again in this example by ultrasonic welds, to form connection portions 122, thereby defining individual pockets 124 for the springs 110. The connection portions are parts of the sheets, or plies, that have been joined between the springs, in the formation of the pockets. The two strings are aligned in parallel before the next step of the method in which sets of ultrasonic welding tools, comprising sonotrodes (or horns) 150 and anvils 160 are brought together to weld alternate ones of the connection portions 122 together in the direction of Arrows Al, thereby joining the strings 130.

[0029] Figure 6 shows the two strings after the welding operation. Where the welding has taken place, the connection portions 122 of the two strings 130 are joined by ultrasonic welds W. The welds W are located between the strings 130 and effectively bring four pockets 124 together. The welding tools 150 and 160 have pushed together and joined the connecting portions 122 of alternate pairs of pocketed springs. In doing so the pockets either side of the weld W have been rotated somewhat, so that the unwelded connecting portions have become pushed outwards in the direction of Arrows A2 and are now present on the outward facing sides of the pair P of strings .

[0030] Figure 7 shows the next step, in which a new string 130 is placed alongside the j oined pair P . The position of the welding tools has been shi fted laterally along the strings 130 by a distance of one spring so that the unwelded connecting portions 122 of the pair P are aligned for welding with corresponding connecting portions 122 of new string 130 . Once again, the sets of welding tools 150 , 160 are brought together and the new string 130 is j oined to the pair P . The result , a partly formed pocketed spring unit 140 , is shown in Figure 8 .

[0031] The process is repeated, each time indexing the unit 140 and moving the welding tools back and forth, in a reciprocal manner, so as to weld alternate connecting portions to the new string until a suf ficient number of strings , or rows , have been added .

[0032] The j oining of the strings takes place on a supporting surface which may include apparatus (not shown) for gripping and moving the individual strings 130 , and / or for indexing the unit 140 . Both sets of welding tools 150 and 160 may be inserted beside the connecting portions 122 from above and / or below the unit , i . e . in a direction parallel with the axes of the springs themselves , or else at least one of the sets of welding tools , for example 160 , may be introduced in a direction substantially transverse to the axes of the springs , for example in the direction in which the new string is being presented, i . e . transverse to the extent of the string . Whereas the tools 150 and 160 are described in this example as , respectively sonotrodes and anvils , their positions / roles could be reversed .

[0033] Indeed, the example of ultrasonic welding apparatus could be replaced by thermal bonding, or heat-sealing tools .

[0034] Figure 8 shows the resilient unit 130 in schematic plan from which it can be seen that the j oined strings create clusters - or modules - 240 of springs ( one of which is shown shaded) which define spaces , or interstices , 250 between springs in the clusters .

[0035] Figure 9 shows in schematic plan view a resilient unit 130 at a later stage of manufacture .

[0036] Within the interstices 250 are located independent resilient units 260 , which in this case are individual pocketed coi l springs . The independent springs 260 are not integral with the rest of the resilient unit and do not share pocketing material / web with any of the integral springs 110 . Instead, the independent springs have been inserted into the spaces 250 so that their axes are substantially parallel with the integral springs 110 .

[0037] Figures 10 - 14 show schematically a method for inserting an independent spring 260 into one of the interstices formed by a spring cluster 240 . The independent spring 260 is , in this example , a pocketed coil spring of an axial length slightly shorter than the springs 110 ( only one of which is shown) making up the cluster 240 , and of a smaller diameter . The length and diameter of the independent spring 260 may be di f ferent , according to the required characteristic of the resilient unit as a whole .

[0038] In order to insert the independent spring 260 , an inserter device 270 , is first placed substantially vertically above the interstice . The device 270 comprises a hollow inserter tube 270a with a f rusto-conical funnel portion 270b at its upper end, and an inner guide pole 270c, with a dome-shaped ( alternatively conical ) leading end 270d proj ecting slightly beyond the end of the tube 270a . The tube 270a and guide pole 270c are almost the same diameter, with the latter being a close fit within the former .

[0039] To insert the independent spring into the cluster, the device 270 is first inserted into the interstice 250 , both pole 270c and tube 270 together, with the dome-shaped leading end 270d of the pole helping to ease the way past the coils of adj acent springs in the cluster .

[0040] Figure 11 shows the tube 270a and pole 270c inserted into the interstice within the cluster .

[0041] Figure 12 shows the pocketed spring 260 above the frusto- conical opening 270b of the inserter tube 270a . Note that the guide pole 270c has been withdrawn, having served its purpose during insertion into the interstice between the springs in the cluster 240 . In Figure 13 , the spring 260 has been placed inside the tube 270a and in this case has fallen, under gravity, to a position inside the interstice , within the cluster .

[0042] Finally, Figure 14 shows the spring 260 inside the unit 130 , the inserter tube 270a having been withdrawn . The spring is held inside the interstice by the adj acent springs 110 . This is because the adj acent springs of the cluster become slightly displaced radially when the tube 270a is inserted but return to grip the independent spring 260 when the tube is withdrawn .

[0043] Figures 15a and 15b show an alternative method of introducing the spring 260a into the interstice . The tube 270a has been inserted using the guide pole 270 s as before , the latter having been withdrawn . In this case , the spring 260a is a shorter, unpocketed spring . To place the spring 260a into the tube 270a, the spring enters an aperture through a portal 270e on the cylindrical side surface of the tube . Figure 15b shows the spring 260a inside the portal 270e . The spring 260a may be inserted under compression . The portal has axial slots 270 f which accommodate pusher members (not shown) for urging the spring into the tube . Once inside the tube , the spring falls into the unit 130 and the tube is withdrawn . The spring 260a is then held in place by the adj acent springs . In this embodiment , the inserter tube does not require a f rusto-conical open end .

[0044] The independent springs may be pocketed or un-pocketed and may have characteristics such as length, diameter, sti f fness , material composition or colour that are chosen to bestow particular characteristics on the resilient unit . For example , it may be desirable for certain portions , regions or zones of the resilient unit to be sti f fer - or more resilient - than others and this may be achieved by careful selection of the type of independent spring, as well as their number and location .

[0045] In the example shown and described herein, the clusters are made up of four resilient elements . However, the clusters could be made up of other numbers of resilient elements .

[0046] The inserter tube and guide pole may be introduced into the interstices in the cluster either from above or below . They may be introduced together or, as an alternative , the guide pole may be inserted first , with the inserter tube then pushed axially along the pole into the interstice . The pole and tube may enter the interstice from opposite sides of the unit .

[0047] Whilst endeavouring in the foregoing speci fication 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 .

Claims

CLAIMS1 . A method of making a resilient unit comprising arranging integral pocketed resilient elements in clusters , wherein each integral pocketed resil ient element in a cluster is attached to at least one other integral resilient element , and wherein the clusters define spaces or interstices , and inserting an independent resilient element into one or more of the spaces or interstices , wherein the method comprises placing a hollow inserter tube into the interstice and introducing the independent resil ient element to the unit through the hollow inserter tube , and wherein the inserter tube is placed into the resilient unit with a guide member located coaxially with and inside the hollow tube .2 . A method according to Claim 1 , wherein the guide member and inserter tube are inserted into the resi lient unit together .3 . A method according to Claim 1 , wherein the guide member is inserted into the resilient unit and then the inserter tube is slid over the guide member .4 . A method according to any of the preceding claims , wherein the guide member is arranged to proj ect beyond the leading end of the inserter tube .5 . A method according to any of the preceding claims , wherein the guide member has a leading end whichcomprises a dome-shaped or conical portion, to easi ly allow the guide member to penetrate the interstice .6 . A method according to any of the preceding claims , wherein the method comprises inserting the guide member and inserter tube into the interstice , then withdrawing the guide member, before the independent resilient element is introduced to the interior of the inserter tube .7 . A method according to any of the preceding claims , wherein the independent resilient element is introduced to the interior of the inserter tube through an open axial end of the tube .8 . A method according to any of Claims 1- 6 , wherein the independent resilient element is introduced to the interior of the inserter tube through an aperture in a side wall of the tube .9 . An apparatus for inserting an independent resilient element into an interstice or space formed by a cluster of pocketed resilient elements , at least some of which are j oined to one another, the apparatus comprising a guide member and a hollow inserter tube for receiving an independent resilient element , and wherein the guide member has a dome-shaped or conical leading end, and is arranged to fit closely within the inserter tube , and wherein, when so inserted, the leading end of the guide member is arranged to proj ect beyond the inserter tube to enable the inserter tube to easily penetrate the interstice .10 . An apparatus according to Claim 9 , wherein the inserter tube includes an aperture for introducing an independent resilient element into the tube , and wherein the aperture is located in a side wall of the tube

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