GB2541663A

GB2541663A - Improvements related to innerspring assemblies

Info

Publication number: GB2541663A
Application number: GB1515008.9A
Authority: GB
Inventors: James Whitworth Ian
Original assignee: Springform Technology Ltd
Current assignee: Springform Technology Ltd
Priority date: 2015-08-24
Filing date: 2015-08-24
Publication date: 2017-03-01
Also published as: EP3135630A1; GB201515008D0; EP3135630B1; TR201809180T4

Abstract

Apparatus for manufacturing pocketed coil springs having a retention mechanism for retaining first and second plies of material 25 and providing relative movement between the plies of material and an insertion mechanism 1a,1b between each actuation of the insertion mechanism. The insertion mechanism has at least a first insertion member 15a and a second insertion member 15b. Upon each actuation of the insertion mechanism, the first insertion member inserts a first coil spring 20a between the plies of material to a first location on a first side of an operative axis of the apparatus, and the second insertion member inserts a second coil (20b figure 5) spring between the plies of material to a second location on a second, opposite side of the operative axis of the apparatus. The first and second coil springs inserted by the first and second insertion members are arranged diagonally between the plies of material relative to the operative axis of the apparatus. Also disclosed is a method of manufacturing pocketed coil springs.

Description

Title - Improvements related to Innersprinq Assemblies

The present invention relates to innerspring assemblies, and more particularly to methods and apparatus for forming innerspring assemblies comprising pocketed coil springs.

Pocketed coil springs, which are coil springs enclosed within pockets of fabric, are widely used in the manufacture of innerspring assemblies for mattresses, cushions and the like. An innerspring assembly of appropriate dimensions for a mattress can be built up by placing appropriate lengths of pocketed coil springs, commonly referred to as strings, side by side and adhering them together, eg with adhesive, such that the coil springs are arranged in a regular array, with operative axes that are substantially parallel to one another. In particular, the operative axes of the coil springs are typically arranged perpendicularly to the upper surface of the innerspring assembly or mattress.

It has previously been proposed (see US 6,523,812, for example) to provide pocketed coil springs in an innerspring assembly in which two or more pocketed coil springs are arranged end-to-end, with a common operative axis. This may allow for enhanced control of the firmness of an innerspring assembly by the use of springs having differing resistances to deformation in different layers of the assembly, eg by providing a softer upper layer relative to a firmer middle or lower layer. This may enable a softer contact layer, eg on both sides of the assembly, or alternatively may enable summer and winter sides to the assembly, each side having a different constructions and/or firmness.

However, there is a need for an efficient manufacturing process for this type of pocketed coil spring assembly, which could otherwise significantly increase the cost and complexity of manufacture.

There has now been devised apparatus for forming a pocketed coil spring assembly, and a method of forming a pocketed coil spring assembly, which overcome or substantially mitigate the aforementioned and/or other disadvantages associated with the prior art.

According to a first aspect of the present invention there is provided apparatus for manufacturing pocketed coil springs, the apparatus comprising a retention mechanism for retaining first and second plies of material relative to an operative axis of the apparatus, and providing relative movement between the plies of material and an insertion mechanism, along the operative axis of the apparatus, between each actuation of the insertion mechanism, and the insertion mechanism having at least a first insertion member and a second insertion member, wherein, upon each actuation of the insertion mechanism, the first insertion member inserts a first coil spring between the plies of material to a first location on a first side of the operative axis of the apparatus, and the second insertion member inserts a second coil spring between the plies of material to a second location on a second, opposite side of the operative axis of the apparatus, and at a different position on the operative axis of the apparatus relative to the first location, such that the first and second coil springs inserted by the first and second insertion members are arranged diagonally between the plies of material relative to the operative axis of the apparatus.

According to a further aspect of the present invention, there is provided a method of manufacturing pocketed coil springs using the apparatus described above, the method comprising the steps of: (a) retaining first and second plies of material relative to the operative axis of the apparatus; (b) actuating the insertion mechanism, which inserts a first coil spring to a first location between the plies of material on a first side of the operative axis of the apparatus, and inserts a second coil spring to a second location between the plies of material on a second, opposite side of the operative axis of the apparatus, and at a different position on the operative axis of the apparatus relative to the first location, such that the first and second coil springs are arranged diagonally between the plies of material relative to the operative axis of the apparatus; and (c) providing relative movement between the plies of material and the insertion mechanism, along the operative axis, between each actuation of the insertion mechanism.

The apparatus and method of manufacture according to the present invention are advantageous principally as the coil springs that are inserted by the first and second insertion members, during actuation, are diagonally arranged between the plies of material, to each side of the operative axis. Hence, successive actuations of the insertion mechanism and relative movement between the plies of material and the insertion mechanism, between each actuation of the insertion mechanism, arranges the coil springs in two rows between the plies of material, either side of the operative axis. Furthermore, more than two coil springs may be inserted in a diagonal arrangement, for example by more than two insertion members, to provide an arrangement with more than two rows of coil springs.

This apparatus and method of manufacture therefore enable separate insertion members to operate together, eg simultaneously, to provide two or more rows of co-axially aligned coil springs between the plies of material, without the need for either a single insertion member to insert more than one spring, or two or more insertion members to be operative along the same axis. The apparatus of the present invention therefore enables efficient manufacture of innerspring assemblies comprising co-axially aligned pocketed coil springs, without the need for complex modifications of existing apparatus for manufacturing pocketed coil springs.

The retention mechanism and the insertion mechanism may both form part of an encapsulation section of the apparatus, in which the coil springs are inserted between the first and second plies of material, which are then joined together to form pockets about the coil springs, eg with each pocket enclosing a coil spring.

The apparatus for manufacturing pocketed coil springs may also comprise a coiling section in which a coil spring is formed from wire fed to the coiling section. The coiling section may comprise a wire feed, and coiling elements whose position and/or orientation determines the form of the coil spring.

The insertion members of the insertion mechanism may each receive coil springs from the same source, eg the same coiling section. Alternatively, at least two of the insertion members may receive coil springs from different sources, eg first and second coiling sections. For example, the first insertion member may receive coil springs from a first source, eg a first coiling section, and the second insertion member may receive coil springs from a second source, eg a second coiling section. The transfer of coil springs from different sources, eg first and second coiling sections, to the insertion members facilitates the manufacture of pocketed coil springs in which a row of coil springs have different characteristics to another row of coil springs, for example.

The first coil spring inserted by the first insertion member may have different characteristics relative to the second coil spring inserted by the second insertion member. This may provide an innerspring assembly in which a first layer of pocketed coil springs have different characteristics to a second layer of pocketed coil springs. Where more than two layers of coil springs are provided, the characteristics of the coil springs in the outer layer may be different to the characteristics of the coil springs in at least one inner layer. The coil springs in each layer may be uniform, or may have different characteristics, for example in order to provide different characteristics across the innerspring assembly, eg in zones.

The differing characteristics of the coil springs may, for example, be any, or any combination of, pitch, number of turns, resistance to deformation or compression, material, length of the spring, diameter of the spring, diameter of the spring member, strength, direction of turn rotation about the axis of compression.

Although this description refers to first and second coil springs, it will be recognised that more than two coil springs may be inserted between the first and second plies of material in a diagonal arrangement, such that more than two rows of coil springs are provided. The apparatus may comprise a further insertion member for insertion of a further coil spring between the plies of material. The further coil spring may be inserted on an opposite side of a further operative axis of the apparatus relative to the first and/or second coil spring, and may be inserted at a different position on the operative axis of the apparatus relative to the first location and or second location, such that the first, second and third coil springs inserted by the first, second, and third insertion members are arranged diagonally between the plies of material relative to the operative axes of the apparatus. The insertion mechanism may comprise an insertion member for each coil spring to be inserted between the first and second plies of material in each actuation of the insertion mechanism. For example, where three coil springs are to be inserted in each actuation of the insertion mechanism, the insertion mechanism may comprise three insertion members.

The apparatus may be configured to move coil springs from the coiling section to the encapsulation section. For example, the coil springs may be loaded onto successive radial arms of a rotating wheel. The apparatus may be configured to compress the coil springs as they are being transported from the coiling section to the encapsulation section. The coil springs may be substantially fully compressed when inserted between the plies of material.

The first and second plies of material may be held in juxtaposed relation by the retaining mechanism. The first and second plies of material may be retained substantially parallel to each other. The first and second plies may be generally rectangular in shape, and may have central longitudinal axes and/or longitudinal edges that are parallel to the operative axis of the apparatus.

Where two rows of coil springs are inserted between the first and second plies of material, the operative axis of the apparatus may have substantially the same transverse position as the central longitudinal axes of the first and second plies of material.

The first and second plies of material may be formed by folding of a single sheet of material. The folded sheet of material may therefore define an entrance, between the first and second plies of material, through which the coil springs are inserted.

The material may be any appropriate material, for example any type of fabric. For example, the material may be either a non-woven or woven fabric. The pockets in the fabric may be formed by any suitable means. Such means include stitching, but it is preferred to form the pockets by thermal welding of the two sheets of material. For this reason, the material may be a fabric that is thermoplastic, and in particular it may be a non-woven thermoplastic material. One suitable material is a non-woven polypropylene.

The relative movement between the plies of material and the insertion mechanism, between each actuation of the insertion mechanism, may be a predetermined distance. The pre-determined distance may correspond substantially to the width of material that will form each pocket, eg around 1.5 times the largest diameter of the coil springs.

The first and second plies of material may be movable relative to the insertion members, eg by use of feed rollers, such that the insertion members have a fixed position on the operative axis. This arrangement may be cheaper and/or less complex than an arrangement in which the insertion members are movable relative to fixed first and second plies of material, primarily as less control of the insertion means is required, and the apparatus may be smaller than the string of pocketed coil springs being manufactured.

The material may drawn through the encapsulation section by means of feed rollers. The material may pass between a pair of horizontally disposed rollers, one of which is driven by a servo motor. The rollers may have rubberised surfaces to improve engagement of the rollers with the fabric.

The retention mechanism may index the first and second plies of material forward a distance equal to one pocket. The next two springs may then be encapsulated, and so on, so as to form a continuous string of pocketed coil springs.

Each insertion member may be configured to receive a single coil spring at a time. This may reduce the cost and complexity of the apparatus, principally as only a single coil spring needs to be fed to an insertion member at any one time. Each insertion member may be configured to insert a single coil spring at a time between the first and second plies of material.

The insertion members may be orientated generally perpendicularly relative to the operative axis of the apparatus and/or a longitudinal axis of the first and second plies of material. The insertion members may be movable relative to the operative axis of the apparatus and/or the first and second plies of material. This movement of the insertion members may be at an oblique angle relative to operative axis of the apparatus, eg in a substantially transverse direction. This movement may be effected by a servo motor or the like. Each insertion member may be movable with a reciprocating action, eg between a retracted position in which a coil spring is received, and an extended position in which a coil spring is released.

Each of the insertion members may include retaining formations for retaining respective coil springs in a position appropriate to insert the coil springs to their respective locations relative to the operative axis and/or further operative axis of the apparatus. This may be achieved by means of insertion members of the same or similar length, with retaining formations that are located at different positions on the insertion members, eg at different transverse positions relative to the operative axis of the apparatus. Alternatively, the insertion members may extend transversely relative to the operative axis of the apparatus by different distances.

The insertion members may be separated, in the direction of the operative axis of the apparatus, such that the coil springs are inserted to their respective locations.

Each insertion member may be adapted to retain a coil spring in a compressed configuration during insertion of the coil spring into the open pocket of material. The insertion member may therefore comprise retention formations, between which the compressed coil spring is held. The resilient action of the coil spring on the retention formations may be sufficient to retain the coil spring. The insertion member may be generally tubular in form, with the retention formations being formed by the interior surfaces of the walls of the insertion member. The insertion member may therefore have the form of a cassette.

The coil spring may be engaged with the insertion member by an engagement member that may push the coil spring into engagement with the insertion member, or that may extend through the coil spring and carry the coil spring into engagement with the insertion member. The insertion member may include an opening, eg a slot, though which the engagement member may move, in order to facilitate engagement of the coil spring with the insertion member.

The apparatus may include means for separating the coil spring from the insertion member, once the coil spring has been inserted between the first and second plies of material, which may take the form of a separation mechanism. The separation mechanism may comprise a capture member, which engages the coil spring once it has reached the desired location between the plies of material, and retains the coil spring in its location when the insertion member is moved to its retracted position. The capture member may comprise a rod, arranged for reciprocating movement, which may pass through at least one of the plies of material. The capture member may therefore have a shape and/or a sufficiently small cross-section that the capture member may be removed, without damaging the material.

In the encapsulation assembly, a single first coil spring and a single second coil spring may be inserted between the plies of material between each increment of relative movement between the plies of material and the insertion members. Similarly, a single coil spring for each of any additional insertion members may be inserted between the plies of material between each increment of relative movement between the plies of material and the insertion members. The first coil spring and the second coil spring, and any further coil springs, may be inserted substantially simultaneously. The first and second insertion members, and any further insertion members, may be moving at the same time, and may be synchronised.

The first insertion member inserts the first coil spring between the plies of material to a first location on a first side of the operative axis of the apparatus, and the second insertion member inserts the second coil spring between the plies of material to a second location on a second, opposite side of the operative axis of the apparatus. Further coil springs may be inserted between the plies of material to a location on an opposite side of a further operative axis of the apparatus relative to the first and/or second coil spring. The first location may be a centre point, eg the geometrical centre, of the first coil spring, and similarly the second location may be a centre point, eg the geometrical centre, of the second coil spring. Further locations may be a centre point, eg the geometrical centre, of further coil springs. The first and second locations may have a transverse separation relative to the operative axis. The transverse separation may be a separation between longitudinal axes extending through the centre points, eg the geometrical centres, of the first and second coil springs, which longitudinal axes are parallel to the operative axis. The transverse separation of the first and second coil springs may be greater than the sum of the radii of the first and second coil springs, and may be at least 1.2 times, at least 1.5 times or at least twice this distance.

Similarly, the first or second and further locations may have a transverse separation relative to the further operative axis. The transverse separation may be a separation between longitudinal axes extending through the centre points, eg the geometrical centres, of the first or second and further coil springs, which longitudinal axes are parallel to the further operative axis. The transverse separation of the first or second and further coil springs may be greater than the sum of the radii of the first or second and further coil springs, and may be at least 1.2 times, at least 1.5 times or at least twice this distance.

The first coil spring may have a boundary axis that is the tangential line that is parallel to the operative axis and closest to the second coil spring, and the second coil spring may have a boundary axis that is the tangential line that is parallel to the operative axis and closest to the first coil spring, wherein the boundary axes of the first and second coil springs are separated. The separation between the boundary axes of the first and second coil springs may be at least 20% of, at least 50% of, or at least equal to, the sum of the radii of the first and second coil springs.

Further coil springs may have a boundary axis that is the tangential line that is parallel to the further operative axis and closest to the first or second coil spring. Boundary axes of the further and first or second coil springs may be separated, and may, for example, be separated by at least 20% of, at least 50% of, or at least equal to, the sum of the radii of the first and further coil springs, or the sum of the radii of the second and further coil springs.

The transverse separation of the first and second coil springs, and the separation between the boundary axes of the first and second coil springs, may be sufficient to form a dividing wall between adjacent first and second coil springs of successive actuations of the insertion mechanism, eg by joining the first and second plies of material between the adjacent coil springs.

The transverse separation of the first or second and further coil springs, and the separation between the boundary axes of the first or second and further coil springs, may be sufficient to form a dividing wall between adjacent first or second and further coil springs of successive actuations of the insertion mechanism, eg by joining the first and second plies of material between the adjacent coil springs.

The first, second and further coil springs are inserted between the plies of material to the first, second, and further locations, which are at different positions on the operative axis and/or further operative axis of the apparatus. The position of the first location on the operative axis may be the point at which a transverse axis of the first coil spring intersects with the operative axis, the transverse axis extending between a centre point, eg the geometrical centre, of the first coil spring and the operative axis, and being orthogonal relative to the operative axis. Similarly, the position of the second location on the operative axis may be the point at which a transverse axis of the second coil spring intersects with the operative axis, the transverse axis extending between a centre point, eg the geometrical centre, of the second coil spring and the operative axis, and being orthogonal relative to the operative axis. The position of the further location on the further operative axis may be the point at which a transverse axis of the further coil spring intersects with the further operative axis, the transverse axis extending between a centre point, eg the geometrical centre, of the further coil spring and the further operative axis, and being orthogonal relative to the further operative axis.

The first and second coil springs may have a longitudinal separation that is the distance between the positions of the first and second coil springs on the operative axis. The longitudinal separation of the first and second coil springs may be greater than the sum of the radii of the first and second coil springs, and may be at least 1.2 times, at least 1.5 times or at least twice this distance. Similarly the first or second and further coil springs may have a longitudinal separation that is the distance between the positions of the first or second and further coil springs on the further operative axis. The longitudinal separation of the first or second and further coil springs may be greater than the sum of the radii of the first or second and further coil springs, and may be at least 1.2 times, at least 1.5 times or at least twice this distance.

The first coil spring may have a boundary axis that is the tangential line that is orthogonal to the operative axis and closest to the second coil spring, and the second coil spring may have a boundary axis that is the tangential line that is orthogonal to the operative axis and closest to the first coil spring, wherein the boundary axes of the first and second coil springs are separated. The separation between the boundary axes of the first and second coil springs may be at least 20% of, at least 50% of, or at least equal to, the sum of the radii of the first and second coil springs.

Further coil springs may have a boundary axis that is the tangential line that is orthogonal to the further operative axis and closest to the first or second coil spring. Boundary axes of the first or second coil springs and the further coil spring may be separated. The separation between the boundary axes of the first or second and further coil springs may be at least 20% of, at least 50% of, or at least equal to, the sum of the radii of the first or second and further coil springs.

The longitudinal separation of the coil springs, and the separation between the boundary axes of the coil springs, may be sufficient to form a dividing wall between adjacent first coil springs and between adjacent second coil springs, and between adjacent further coil springs of successive actuations of the insertion mechanism, eg by joining the first and second plies of material between the adjacent coil springs.

The longitudinal separation between the first and/or second and/or locations, and hence the longitudinal separation between the inserted coil springs, in the direction of the operative axis and/or further operative axis may be substantially equal to each increment of the relative movement between the plies of material and the insertion mechanism, between each actuation of the insertion mechanism.

The retention mechanism and the insertion mechanism may both form part of an encapsulation section of the apparatus, in which the coil springs are inserted between the first and second plies of material, which are then joined together to form pockets about the coil springs, eg with each pocket enclosing a coil spring. The apparatus, and specifically the encapsulation section, may be configured to join the first and second plies of material in a manner that encapsulates each coil spring in a pocket of material.

The mechanism for joining the two plies of material may comprise any conventional mechanisms for that purpose. Where two plies of material are formed by a sheet of weldable material, eg fabric, the welding of the two sheets of material may be carried out in any suitable fashion, eg using ultrasonic welding. The welds may be interrupted, rather than continuous.

Where two plies of material are formed by a sheet of weldable material that is folded about a longitudinal axis, each pocket in the row of coil springs adjacent to the fold may be formed by applying two transverse welds that are orientated substantially transversely to the operative axis, at either side of the coil spring, and an axial weld that is substantially aligned with the operative axis, on the other side of the spring from the fold. Each pocket in the other row of coil springs may therefore be formed in a similar manner, by applying two transverse welds that are orientated substantially transversely to the operative axis, at either side of the coil spring, and an axial weld that is substantially aligned with the operative axis, on the other side of the spring from the fold.

The apparatus may therefore comprise both axial and transverse joining members, which may take the form of welding members.

The welding members may be slidably mounted on suitable guide rails and may be driven by a suitable rack and pinion mechanism or the like. The required position of the welding members may be calculated automatically by a controller, and the position of the welding members may be altered automatically, or the required position may be displayed and the welding members positioned manually.

The apparatus may comprise a mechanism for moving the coil springs encapsulated within pockets of material. The apparatus may comprise a mechanism for rotating the coil springs, eg about a rotation axis that is substantially parallel to the operative axis of the apparatus. In particular, the first and second coil springs may be inserted between the first and second plies of material with their operative axes being juxtaposed and substantially parallel. The apparatus may rotate the first and second coil springs by about 90°, such that the operative axes of transversely adjacent coil springs are substantially aligned, eg substantially transversely across the two plies of material.

The apparatus may include one or more worm gears which rotate transversely to the direction of travel of the completed pockets, and which serves to orient the springs as they expand within the pockets.

The continuous string of pocketed coil springs may then be severed to form separate strings of pocketed coil springs suitable for forming an innerspring assembly for a mattress, a cushion, or the like. A practicable embodiment of the invention is described in further detail below, with reference to the accompanying drawings, of which:

Figure 1 is a schematic view of a coiling unit and an insertion mechanism of apparatus according the invention

Figure 2 is a detailed scrap view on the line III in Figure 1;

Figure 3 is a schematic view of first and second insertion mechanisms of the apparatus according to the invention;

Figure 4 is a schematic view of the apparatus according to the invention;

Figures 5(a)-(d) are schematic views illustrating insertion steps of a method according to the invention;

Figures 6(a)-(e) are schematic views illustrating encapsulation steps according to the method according to the invention;

Figure 7 is a schematic view of a string of pocketed coil springs produced by the apparatus and method according to the invention;

Figure 8 is a schematic view of an innerspring assembly comprising the strings of pocketed coil springs shown in Figure 6.

Figure 9 is a schematic view of first, second and third insertion mechanisms of a second embodiment of apparatus according to the invention;

Figure 10 is a schematic view of dampening means for use with the insertion mechanisms of Figure 9; and

Figure 11 is a schematic view of an insertion section of a second embodiment of apparatus according to the invention.

Figure 1 shows a first coiling unit, generally designated 10, and a first insertion mechanism 1a of the apparatus according to the invention. The first insertion mechanism 1 a comprises a counter-clockwise rotating wheel 11 a with eight radially extending arms 12a. Springs 20a produced in the first coiling unit 10 are fed to a conveyor (not shown), which subsequently feeds the springs 20a automatically onto the arms 12a. The path travelled by the springs 20a along the conveyor may allow the springs 20a time to cool from any heat treatment they may have received during the coiling process.

As the wheel 11a rotates, the arms 12a carrying the springs 20a move through longitudinal slots in a pair of compression plates 13a,14a, the space between which is progressively reduced, causing the springs 20a to be compressed.

The terminal portions of the compression plates 13a,14a are disposed parallel and horizontally so as to constitute a delivery chute from which the compressed springs 20a are delivered to a reciprocating cassette 15a which moves as indicated by the double-headed arrow. The cassette 15a transfers the springs 20a to an encapsulation unit and in particular to the space between the two leaves of a folded sheet of non-woven fabric 25 (shown in broken lines). When the cassette 15a is located between the leaves of fabric 25, a pneumatically driven rod is raised and engages the spring 20a through the lower leaf and a slot in the base of the cassette 15a. This rod retains the spring 20a in position when the cassette 15a is withdrawn from the fabric 25.

The insertion mechanism of the apparatus further comprises a second insertion mechanism 1 b, which is substantially identical in form to the first insertion mechanism 1 a shown in Figure 1, with like features denoted by common reference numerals with the suffix “b”, and receives springs 20b from a second coiling unit in a similar manner at the same time as the first insertion mechanism la receives springs 20a from the first coiling unit 10. The difference between the first 1 a and second 1 b insertion mechanisms is that the reciprocating cassette 15b of the second insertion mechanism 1 b is configured to extend to a different location within the leaves of fabric 25, relative to the first insertion mechanism 1 a, such that the springs 20a,20b delivered by the first 1 a and second 1 b insertion mechanisms are delivered to different transverse locations between the leaves of fabric 25, as discussed in more detail below. In particular, the reciprocating cassette 15b of the second insertion mechanism 1b is shorter and configured to extend to a proximal transverse location within the leaves of fabric 25, whereas the reciprocating cassette 15a of the first insertion mechanism 1 a is longer and configured to extend to a distal transverse location within the leaves of fabric 25, such that the springs 20a,20b delivered by the first 1 a and second 1 b insertion mechanisms are delivered to locations on either side of a central operative axis between the leaves of fabric 25, and the springs 20a,20b are therefore arranged diagonally relative to the central operative axis.

In addition, the second insertion mechanism 1 b is disposed in a more advanced position, relative to the direction of travel of the fabric 25 (along an operative axis of the apparatus), relative to the first insertion mechanism la, such that the springs 20b from the second coiling unit are located in a more advanced position, between the leaves of fabric 25, than the springs 20a from the first coiling unit, on each actuation of the insertion mechanisms la,1b. This arrangement is shown schematically in Figure 3, with the direction of travel of the fabric 25 denoted by arrow A. As can be seen, the first 1 a and second 1 b insertion mechanisms are disposed upon a common axis of rotation 21 such that the second insertion mechanism 1b is disposed in a more advanced position, relative to the direction of travel of the fabric 25, to the first insertion mechanism la. The insertion mechanisms 1a,1b rotate synchronously about the common axis of rotation 21.

Excessive oscillations of the springs 20a, 20b as they exit the first coiling unit 10 and second coiling unit and are loaded onto the arms 12a,12b, are prevented by electromagnets 27a,27b, (see Figure 2) mounted on the topmost parts of the upper compression plates 13a,13b, either side of the longitudinal slots 28a,28b running down the centre of that compression plates 13a,13b. A further electromagnet 27c is located on a common compression plate 13 c, which is disposed between the compression plates 13a, 13b so as to define the slots 28a,28b. The electromagnets 27a,27b,27c hold each spring 20a,20b as it exits the coiling units until the corresponding arm 12a,12b of the wheels 11 a,11 b transport the springs 20a,20b away.

Figure 4 shows the encapsulation unit 40 of the apparatus according to the invention, the operative axis of which is disposed perpendicularly to that of the coiling unit 10. The sheet 25 of fabric is folded by conventional means (not shown) and fed through the encapsulation unit 40 from right to left, as viewed in Figure 4, in incremental steps. The sheet 25 passes firstly between a pair of guide rollers 41. A fixed separating guide (not shown) then parts the two leaves of the sheet 25 sufficiently for springs 20a,20b to be inserted between them by the reciprocating cassettes 15a,15b of the first and second insertion mechanisms.

The insertion of springs 20a,20b by the reciprocating cassettes 15a,15b of the first la and second 1b insertion mechanisms will now be described in more detail with reference to Figures 5(a)-(d).

Initially, the first insertion mechanism 1a may be configured to insert a single spring 20a between the two leaves of the sheet 25, as shown in Figure 5(a).

The spring 20a is inserted such that it is located in a distal transverse region of the sheet 25. The sheet 25 is then advanced by one increment along the operative axis of the apparatus, this increment being equal to the width of fabric required for each pocket. This initial insertion step may be included in order to ensure that the leading element of the string of pocketed coil springs being manufactured contains two co-axial pocketed coil springs. Alternatively, this initial insertion step could be omitted, and the leading element of the string of pocketed coil springs, which would only contain one pocketed coil spring (as will be evident from the description below), could be severed from the string.

In the next insertion step, the first 1a and second insertion 1b mechanisms simultaneously insert springs 20a,20b into the sheet 25, as shown in Figure 5(b). As can be seen, spring 20a is located in a distal transverse region of the sheet 25, whilst spring 20b is located in a proximal transverse region of the sheet 25. In particular, the reciprocating cassette 15b of the second insertion mechanism 1 b extends to a proximal transverse location within the leaves of fabric 25, whereas the reciprocating cassette 15a of the first insertion mechanism 1 a extends to a distal transverse location within the leaves of fabric 25, such that the springs 20a,20b delivered by the first la and second 1b insertion mechanisms are delivered to locations on either side of a central operative axis between the leaves of fabric 25, and the springs 20a,20b are therefore arranged diagonally relative to the central operative axis.

The sheet 25 is then advanced by another increment, and the insertion step described above with reference to Figure 5(b) is repeated, as shown in Figure 5(c). The sheet 25 is then advanced by another increment, and the insertion step described above with reference to Figure 5(b) is repeated again, as shown in Figure 5(d). Successive movements of the sheet 25 and insertion steps, in this manner, insert springs 20a,20b into the sheet 25 such that each spring 20a in a first row (the upper row as shown in Figure 5) shares a common axis with a spring 20b in a second row (the lower row shown in Figure 5).

Finally, at the end of the string of pocketed coil springs, the second insertion mechanism 1 b may be configured to insert a single spring 20b between the two leaves of the sheet 25. The spring 20b would be inserted such that it is located in a proximal transverse region of the sheet 25. This final insertion step may be included in order to ensure that the trailing element of the string of pocketed coil springs being manufactured contains two co-axial pocketed coil springs.

Alternatively, this final insertion step could be omitted, and the trailing element of the string of pocketed coil springs, which would only contain one pocketed coil spring, could be severed from the string.

While the springs 20a,20b are being inserted into the sheet 25, the springs 20a,20b are maintained in a compressed condition by a cover plate 42 which, together with the bed of the encapsulation unit 40, defines a channel through which the encapsulated springs 20a,20b are transported.

Following incremental travel of the sheet 25, the two leaves of the sheet 25 are joined by transverse welds formed by a first reciprocating welding horn 43. Further welding horns 44a,44b form longitudinal welds, which complete the encapsulation of the springs 20a,20b.

The particular welding of the sheet 25, in this embodiment, is described in more detail with reference to Figures 6(a)-(e).

Initially the first reciprocating welding horn arrangement 43 is used to form a transverse weld across the sheet 25 prior to insertion of springs 20a,20b (this step is not shown). Then, after the sheet 25 has been advanced by one increment, the first reciprocating welding horn arrangement 43 is used to apply another transverse weld to the sheet 25, such that transverse welds are formed either side of a first pair of springs 20a,20b, as shown in Figure 6(a).

The sheet 25 is moved along by one increment, and the first 44a of the further welding horns applies a weld longitudinally along the sheet 25 between the first pair of springs 20a,20b, as shown in Figure 6(b). The sheet 25 is moved along by one further increment, and the second 44b of the further welding horns applies a weld longitudinally along an open edge of the sheet 25 in the region of the first pair of springs 20a,20b, as shown in Figure 6(c). In this manner the first pair of springs 20a,20b are sealed within sub-pockets of the sheet 25 via welds applied by the welding horns 43,44a,44b.

The welding procedure continues as the sheet 25 is advanced by increments, thereby forming a string of pocketed coil springs 20a,20b as shown in Figures 6(d) and 6(e). A second cover plate 45 extends from the region of the first welding horn arrangement 43, past the further welding horns 44a,44b, and also past a drive roller arrangement 46,47 which acts on the folded fabric sheet 25 so as incrementally to draw the sheet 25 through the encapsulation unit 40. The drive roller arrangement 46,47 comprises a driven roller 46 which acts on the underside of the sheet 25 and a second roller 47 which is pneumatically pressurised into engagement with the upper surface of the sheet 25. Both rollers 46,47 have rubberised surfaces, the rubberised surface of the upper roller 47 being partly cut away to accommodate the second cover plate 45.

As the encapsulated springs 20a,20b emerge from the channel between the second cover plate 45 and the bed of the encapsulation unit 40 they expand and are rotated into the desired orientation, in which the spring axis is transverse to the pockets, by a rotating worm gear 48. The finished product has the form of a string of co-axially aligned springs enclosed within pockets formed in the non-woven fabric, the pockets being connected at the weld lines which define the sides of the pockets. Such a finished product is shown schematically in Figure 7. The finished strings can be assembled, for example via adhesive, to form an innerspring assembly as shown in Figure 8.

The reciprocating motion of the first welding arrangement 43 and of the further welding horns 44a,44b is synchronised with the incremental actuation of the drive roller arrangement 46,47 under the control of a programmable logic controller (PLC). A second embodiment of apparatus according to the present invention is shown schematically in Figure 9. The second embodiment is substantially the same as the first embodiment, and differs in that it comprises three insertion mechanisms 100a, 100b, 100c. It will be recognised that embodiments comprising more than three insertion mechanisms may also be realised. The insertion mechanisms 100a,100b,100c have substantially the same form as the first 1 a and second 1 b insertion mechanisms of the first embodiment of apparatus of the present invention. Each insertion mechanism receives springs from an associated coiling unit (not shown).

As seen in Figure 9, the second insertion mechanism 100b is disposed in a more advanced position, relative to the direction of travel of the fabric (along an operative axis of the apparatus), relative to the first insertion mechanism 100a, such that springs 102b from a second coiling unit are located in a more advanced position, between the leaves of fabric, than springs 102a from a first coiling unit, on each actuation of the insertion mechanisms 100a,100b. The third insertion mechanism 100c is similarly disposed in a more advanced position, relative to the direction of travel of the fabric (along an operative axis of the apparatus), relative to the second insertion mechanism 100b, such that springs 102c from a third coiling unit are located in a more advanced position, between the leaves of fabric, than springs 102b from a second coiling unit, and than springs 102a from a first coiling unit, on each actuation of the insertion mechanisms 100a,100b.

This arrangement is shown schematically in Figure 9, with the direction of travel of the fabric denoted by arrow B. As can be seen, the first 100a, second 100b, and third 100c, insertion mechanisms are disposed upon a common axis of rotation 104 such that the second insertion mechanism 100b is disposed in a more advanced position, relative to the direction of travel of the fabric , to the first insertion mechanism 100a, and such that the third insertion mechanism 100c is disposed in a more advanced position, relative to the direction of travel of the fabric, to the second insertion mechanism 100b. The insertion mechanisms 100a,100b,100c rotate synchronously about the common axis of rotation 104.

Excessive oscillations of the springs 102a,102b,102c as they exit the first, second, and third coiling units and are loaded onto the arms of the insertion mechanisms 100a,100b,100c, are prevented by electromagnets 106a,106b, 106c,106d (see Figure 2) mounted on the topmost parts of the upper compression plates 108a,108b, 108c,108d either side of the longitudinal slots 110a,110b, 11 Oc, running down the centre of that compression plates 108a,108b, 108c,108d. The electromagnets 106a,106b, 106c,106d hold each spring 102a,102b,102c as it exits the coiling units until the corresponding arm of the wheels of the insertion mechanisms 100a,100b,100c transport the springs 102a, 102b, 102c away.

Figure 11 shows an insertion section of apparatus according to the second embodiment of the present invention. The insertion section is substantially the same as the insertion section of the first embodiment of the present invention (as shown in Figure 4), and differs only in that three springs 102a,102b, 102c are inserted and maintained in a compressed condition by a cover plate 112.

The springs 102a,102b, 102c are inserted in a similar manner to the insertion steps shown in Figures 5(a)-(d) and Figures 6(a)-(e).

The insertion mechanisms 100a,100b,100c simultaneously insert springs 102a, 102b, 102c into the sheet. A first spring 102a is located in a distal transverse region of the sheet, a second spring 102b is located in a medial transverse region of the sheet, and a third spring 102c is located in a proximal transverse region of the sheet. Reciprocating cassettes of the insertion mechanisms 100a,100b, 100c extend to different transverse locations within the leaves of fabric, such that the first 102a and second 102b springs are delivered to locations either side of a first operative axis of the apparatus, whilst the second 102b and third 102c springs are delivered to locations either side of a second operative axis of the apparatus. The first 102a, second 102b, and third 102c springs are arranged diagonally relative to the first and second operative axes of the apparatus.

The sheet is then advanced by another increment, and the insertion step described above is repeated. The sheet is then advanced by another increment, and the insertion step described above is repeated again. Successive movements of the sheet and insertion steps, in this manner, insert springs 102a,102b,102c into the sheet such that each spring 102a in a first row shares a common axis with a spring 102b in a second row, and a common axis with a spring 102c in a third row.

The welding procedure is substantially the same as the procedure described with reference to Figures 6(a)-(e), and differs in the addition of a further longitudinal welding horn which applies a weld longitudinally along the sheet between the second 102b and third 102c springs. The addition of this further longitudinal welding horn thereby allows the sheet to be formed into three distinct sub-pockets, each of which comprises a coil spring.

Claims

1. Apparatus for manufacturing pocketed coil springs, the apparatus comprising a retention mechanism for retaining first and second plies of material relative to an operative axis of the apparatus, and providing relative movement between the plies of material and an insertion mechanism, along the operative axis of the apparatus, between each actuation of the insertion mechanism, and the insertion mechanism having at least a first insertion member and a second insertion member, wherein, upon each actuation of the insertion mechanism, the first insertion member inserts a first coil spring between the plies of material to a first location on a first side of the operative axis of the apparatus, and the second insertion member inserts a second coil spring between the plies of material to a second location on a second, opposite side of the operative axis of the apparatus, and at a different position on the operative axis of the apparatus relative to the first location, such that the first and second coil springs inserted by the first and second insertion members are arranged diagonally between the plies of material relative to the operative axis of the apparatus.

2. Apparatus as claimed in Claim 1, wherein the first and second coil springs have a longitudinal separation that is the distance between the positions of the first and second coil springs on the operative axis, and the longitudinal separation of the first and second coil springs is greater than the sum of the radii of the first and second coil springs, or at least 1.2 times, at least 1.5 times or at least twice this distance.

3. Apparatus as claimed in Claim 1 or Claim 2, wherein the first coil spring has a boundary axis that is the tangential line that is orthogonal to the operative axis and closest to the second coil spring, and the second coil spring has a boundary axis that is the tangential line that is orthogonal to the operative axis and closest to the first coil spring, wherein the boundary axes of the first and second coil springs are separated.

4. Apparatus as claimed in Claim 3, wherein the separation between the boundary axes of the first and second coil springs is at least 20% of, at least 50% of, or at least equal to, the sum of the radii of the first and second coil springs.

5. Apparatus as claimed in any preceding claim, wherein the first and second coil springs have a longitudinal separation that is the distance between the positions of the first and second coil springs on the operative axis, and the longitudinal separation is sufficient to form a dividing wall between adjacent first coil springs and between adjacent second coil springs of successive actuations of the insertion mechanism, by joining the first and second plies of material between the adjacent coil springs.

6. Apparatus as claimed in any preceding claim, wherein the first and second coil springs have a longitudinal separation that is the distance between the positions of the first and second coil springs on the operative axis, and the longitudinal separation is substantially equal to each increment of the relative movement between the plies of material and the insertion mechanism, between each actuation of the insertion mechanism.

7. Apparatus as claimed in any preceding claim, wherein the first and second locations have a transverse separation that is the separation between longitudinal axes extending through the centre points of the first and second coil springs, which longitudinal axes are parallel to the operative axis, and the transverse separation of the first and second coil springs is greater than the sum of the radii of the first and second coil springs, or at least 1.2 times, at least 1.5 times or at least twice this distance.

8. Apparatus as claimed in any preceding claim, wherein the first coil spring has a boundary axis that is the tangential line that is parallel to the operative axis and closest to the second coil spring, and the second coil spring has a boundary axis that is the tangential line that is parallel to the operative axis and closest to the first coil spring, wherein the boundary axes of the first and second coil springs are separated.

9. Apparatus as claimed in Claim 8, wherein the separation between the boundary axes of the first and second coil springs is at least 20% of, at least 50% of, or at least equal to, the sum of the radii of the first and second coil springs.

10. Apparatus as claimed in any preceding claim, wherein the first and second locations have a transverse separation that is the separation between longitudinal axes extending through the centre points of the first and second coil springs, which longitudinal axes are parallel to the operative axis, and the transverse separation is sufficient to form a dividing wall between adjacent first and second coil springs of successive actuations of the insertion mechanism, eg by joining the first and second plies of material between the adjacent coil springs.

11. Apparatus as claimed in any preceding claim, wherein the retention mechanism and the insertion mechanism both form part of an encapsulation section of the apparatus, in which the coil springs are inserted between the first and second plies of material, which are then joined together to form pockets about the coil springs.

12. Apparatus as claimed in Claim 11, wherein each pocket encloses a single coil spring.

13. Apparatus as claimed in any preceding claim, wherein the apparatus for manufacturing pocketed coil springs comprises first and second coiling sections in which a coil spring is formed from wire fed to the coiling section, and the first insertion member receives coil springs from the first coiling section, and the second insertion member receives coil springs from the second coiling section.

14. Apparatus as claimed in any preceding claim, wherein the first coil spring inserted by the first insertion member has different characteristics relative to the second coil spring inserted by the second insertion member.

15. Apparatus as claimed in any preceding claim, wherein the relative movement between the plies of material and the insertion mechanism, between each actuation of the insertion mechanism, is a pre-determined distance that corresponds substantially to the width of material that will form each pocket.

16. Apparatus as claimed in any preceding claim, wherein each insertion member is configured to receive a single coil spring at a time.

17. Apparatus as claimed in any preceding claim, wherein the first insertion member includes retaining formations for retaining the first coil spring in a position appropriate to insert the first coil spring to the first location on a first side of the operative axis of the apparatus, and the second insertion member includes retaining formations for retaining the second coil spring in a position appropriate to insert the second coil spring to the second location on a second side of the operative axis of the apparatus.

18. Apparatus as claimed in any preceding claim, wherein a single first coil spring and a single second coil spring are inserted between the plies of material between each increment of relative movement between the plies of material and the insertion members.

19. Apparatus as claimed in any preceding claim, wherein the first coil spring and the second coil spring are inserted substantially simultaneously.

20. Apparatus as claimed in any preceding claim, wherein the first and second insertion members are synchronised.

21. Apparatus as claimed in any preceding claim, wherein the apparatus is configured to join the first and second plies of material in a manner that encapsulates each coil spring in a pocket of material.

22. A method of manufacturing pocketed coil springs using apparatus as claimed in any preceding claim, the method comprising the steps of: (a) retaining first and second plies of material relative to the operative axis of the apparatus; (b) actuating the insertion mechanism, which inserts a first coil spring to a first location between the plies of material on a first side of the operative axis of the apparatus, and inserts a second coil spring to a second location between the plies of material on a second, opposite side of the operative axis of the apparatus, and at a different position on the operative axis of the apparatus relative to the first location, such that the first and second coil springs are arranged diagonally between the plies of material relative to the operative axis of the apparatus; and (c) providing relative movement between the plies of material and the insertion mechanism, along the operative axis, between each actuation of the insertion mechanism.

23. A method as claimed in Claim 22, wherein the first and second plies of material are joined together to form pockets about the coil springs.

24. A method as claimed in Claim 23, wherein each pocket encloses a single coil spring.

25. A method as claimed in any one of Claims 22 to 24, wherein a single first coil spring and a single second coil spring are inserted between the plies of material between each increment of relative movement between the plies of material and the insertion members.

26. A method as claimed in any one of Claims 22 to 25, wherein the first coil spring and the second coil spring are inserted substantially simultaneously.

27. A method as claimed in any one of Claims 22 to 26, wherein the first and second plies of material are formed by a sheet of weldable material that is folded about a longitudinal axis, and wherein each pocket in the row of coil springs adjacent to the fold is formed by applying two transverse welds that are orientated substantially transversely to the operative axis, at either side of the coil spring, and an axial weld that is substantially aligned with the operative axis, on the other side of the spring from the fold, and each pocket in the other row of coil springs is formed in a similar manner, by applying two transverse welds that are orientated substantially transversely to the operative axis, at either side of the coil spring, and an axial weld that is substantially aligned with the operative axis, on the other side of the spring from the fold.