The present invention relates to a transportation apparatus and method for transporting articles, and is concerned particularly, although not exclusively, with apparatus and a method for transporting springs.

In upholstered articles, such as mattresses, that use pocketed - or encapsulated - coil springs, the manufacturing process usually involves transporting springs of metal wire from a coiling station, where a wire is formed into the spring which is then cut from the length of wire, to a pocketing station, where the formed spring is encapsulated in a pocket formed from material.

One known method for doing this can be seen in European patent number EP 1 993 947 B, from the present inventors. In this method, springs are compressed and fed between opposed (upper and lower) conveyor belts which transport the springs to a pocketing station, where they are pushed out from between the belts to positions between axially spaced sheets of pocketing material. The sheets are then welded together at locations between the springs to form pockets around them.

In one previously considered example, springs are formed and cut from a length of wire before being deposited on radially extending, retractable arms of a wheel. The wheel then compresses the springs before depositing them between a castellated lower conveyor belt and a fixed, low-friction plate above. The belt drives the springs to the pocketing station as before, and the end of the spring not engaged by the belt slides against the plate as the belt moves.

The above methods of transporting the springs from the coiler to the pocketing station can encounter problems when the springs have a relatively long axial length or else a relatively high number of turns (ie coils) . This is because longer springs and springs with greater numbers of turns may be less stable or may be of greater stiffness .

In the case of the moving belt and stationary plate above, an unstable spring may bend under the force of the belt. This can be because the force of the belt acting on a proximal end of the spring, in a direction transverse to its axis, may not be efficiently transmitted to other coils, so that coils at the distal end, in contact with the plate, are unable to overcome the friction force of the upper plate.

This can sometimes cause the spring to become dislodged from the transport apparatus, which is inconvenient and may lead to down-time for the apparatus. Embodiments of the present invention aim to provide a conveyor and a method of conveying, in which the aforementioned problems are addressed.

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. According to one aspect of the present invention, there is provided a conveyor for transporting articles, the conveyor comprising a substrate for supporting articles during transportation, and a plurality of retaining members located on the substrate for retaining the articles on the substrate during transportation.

The retaining members may be arranged in use to at least partly enclose the articles.

The retaining members may be arranged in use to hold the articles under compression on the conveyor. In a preferred arrangement the or each retaining member comprises a mounting portion that engages the substrate.

The or each retaining member preferably also comprises at least one containment portion arranged in use to bear against at least a part of an article being supported on the conveyor .

In a preferred arrangement, the containment portion comprises a proximal part and a distal part. The proximal part of the containment portion may be arranged proximate to the substrate and the distal part may be arranged to be spaced therefrom. The proximal and distal parts of the containment may define a space therebetween for accommodating a part of an article, such as a spring, in use.

The retaining member may be arranged in use to retain an article between the proximal and distal parts of the containment portion.

The retaining member may comprise at least one slot, for receiving a displacement device, such as a mechanical pusher, arranged in use to displace the article from the substrate .

In a preferred arrangement, there is a plurality of retaining members that may be spaced apart on the substrate along its axis. At least parts of adjacent retaining members may be separated by a gap that is selected to accommodate depositing apparatus for depositing articles on the substrate. Preferably the distal parts of the containment portions of adjacent retaining members are arranged to be spaced by a first gap and preferably proximal parts of adjacent retaining members are arranged to be spaced by a second gap, or not to be spaced at all. The first gap is preferably greater than the second gap.

One or more of the retaining members may be attached to the substrate. Alternatively, or in addition, one or more of the retaining members may be substantially integrally formed with the substrate, for example by moulding.

The substrate may comprise an endless belt or a chain for example . The conveyor may comprise transportation apparatus for coil springs. In a preferred arrangement, at least one coil spring is arranged to be retained in a retaining member such that coils at opposed ends of the spring are axially offset with respect to one another. The spring is preferably arranged to be retained in a splayed configuration in which at least some adjacent coils are axially offset.

According to another aspect of the present invention there is provided a method of transporting articles, the method comprising retaining the articles on a conveyor comprising a substrate for supporting the articles and at least one retaining member on the substrate.

The method may comprise retaining at least one of the articles on the conveyor by locating it at least partly beneath or within a retaining member and preferably under compression.

The method may comprise retaining at least one of the articles on the conveyor by locating it between proximal and distal containment parts of a retaining member.

Preferably the method comprises retaining at least one of the articles on the conveyor using two adjacent retaining members that are preferably spaced on the substrate.

The method may comprise a method of transporting coil springs on a conveyor. In one arrangement, the method may comprise retaining at least one spring such that coils at opposed ends of the spring are axially offset with respect to one another. The method may include retaining the spring in a splayed configuration, in which at least some adjacent coils are offset axially.

In accordance with another aspect of the present invention there is provided compression apparatus for use in at least partly compressing a spring axially mounted on a support rod, the apparatus comprising at least one rotating portion for locating beside the rod and arranged in use to press against a spring mounted on the rod in a generally axial direction of the spring.

In a preferred arrangement the apparatus comprises at least two rotating portions, one located either side of the rod, and preferably arra Lged to rotate in a mutually opposite sense.

The or each rotating portion may comprise a rotating brush .

The invention also comprises a method of compressing a spring mounted on a rod, the method comprising pressing against the spring using a rotating portion.

The method preferably comprises pressing against the spring using at least two rotating portions, one located either side of the rod.

The invention may include any combination of the features or limitations referred to herein, except such a combination of features as are mutually exclusive, or mutually inconsistent. 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:

Figure 1 shows schematically a previously considered apparatus for pocketing springs;

Figures 2 and 3 show part of a previously considered apparatus for depositing springs onto a conveyor;

Figure 4 shows schematically a conveyor transportation apparatus according to an embodiment of the present invention;

Figure 5 shows schematically a pre-compression apparatus for use with the conveyor of Figure 4; and

Figure 6 shows schematically an alternative embodiment of spring transportation apparatus in accordance with the present invention.

Figure 1 shows schematically an example of apparatus described in the abovementioned patent, for making pocketed spring units for upholstered articles such as mattresses. Springs 100 are conveyed under compression to a spring-inserting position by an endless belt 110. The springs are trapped between the belt 110 and a low- friction plate 110a. Once at the pocketing station, the springs are pushed by mechanical pushers 120 that are driven by a motor 130 to move in a reciprocating motion, indicated by arrow Al . The pushers 120 push the springs into positions between sheets of material 130 fed from upper and lower supply- rollers 140a and 140b via guide rollers 150a and 150b.

The sheets 130 are joined at positions between springs by the reciprocating action of an upper welding tool 160a in the direction shown by arrow A2 that presses the sheets together and fuses them on a welding anvil 160b. A row of springs becomes encapsulated in pockets at each stepwise advancement of the resilient unit 170 in the direction of Arrow A3.

Figure 2 shows schematically a wheel apparatus 200 for depositing the springs onto the belt 110. The wheel has a plurality of spokes in the form of retractable rods 210.

A coiling machine (not shown) loads a spring 100 onto each rod as the wheel turns in the direction of Arrow A .

The spokes then enter a compression zone 220, formed by two parallel tapering walls. The walls are spaced to allow the rod to pass between them but the springs are caught and gradually compressed as the rod progresses towards the bottom of the wheel. Then, when the spring is maximally compressed it is deposited onto a castellated conveyor belt 110 which carries the spring away in a direction substantially parallel with the axis of rotation of the wheel. Figure 3 shows schematically the wheel viewed from the direction of Arrow A5 of Figure 2. The figure shows the springs 100 being conveyed between the belt 110 and a low-friction plate 110a in the direction of Arrow A6, towards a pocketing station (not shown) , such as is shown in Figure 1.

As previously mentioned, particularly when longer springs are used, or springs with more turns of wire, or else springs of relatively thin wire (smaller gauge), problems can arise during transportation. For example, if the spring is particularly stiff, the increased friction experienced as it slides along the plate 110a can sometimes cause the spring to bend or even to become dislodged as the belt moves. This can also happen when the spring is unstable, so that the force exerted by the belt is not fully transferred to the turns of wire located distally of the belt. Again the spring can bend and sometimes become dislodged.

As well as potentially causing a spring to be omitted from the pocketed unit, this also leads to costly downtime for the pocketing machine as the missing spring must be located.

Turning to Figure 4, this shows generally at 400, in schematic part-sectional view, a conveyor according to an embodiment of the present invention. The conveyor 400 is suitable for use as spring transportation in a pocketed spring apparatus such as is described above with reference to Figure 1 and can replace the belt/plate assembly 110/llOa.

The conveyor 400 comprises a substrate 410 {shown in cross section) , in this case in the form of a castellated belt of nylon/plastics material, upon which are attached at equally spaced locations a plurality of retaining members 420 for securely retaining a number of springs 100 on the substrate.

The retaining members comprise substantially T-shaped bodies of nylon/plastics material, each having a mounting portion 430 at its base that is mounted on the substrate. In this example the mounting portion straddles a castellation 410a of the substrate.

The mounting portion extends away from the substrate and supports integrally formed, opposed containment portions 440 which extend substantially parallel to the substrate.

Adjacent retaining members are spaced on the substrate by a gap G, which is sufficient to allow a rod 210 of a spring depositing wheel 200 (see Figure 2) to pass therebetween, so that the spring becomes held on the substrate between opposed containment portions of adjacent retaining members, whilst remaining compressed.

On each side of the retaining member, in a direction substantially parallel with the substrate, are located slots 450 for receiving pushers (e.g. 120 in Figure 1) which travel transversely of the substrate to urge the spring from the substrate, at the point at which it is to be encapsulated in material. The height of the slot 450 is such as to provide space above the trapped spring. Meanwhile, the castellations of the substrate in this case provide space below the spring, such that a pusher that is taller than the height of the spring may be used. This allows the pusher to extend above and below the compressed spring to discourage or prevent the spring from becoming trapped above or below the pusher. A pair of pushers is used to eject a single spring by engaging the spring at two places on its radial periphery, and by sliding into the slots 450.

In the example shown, the retaining members comprise discrete fixtures that are secured to the substrate from below by bolts 460. However, the retaining members could, as an alternative or in addition, be affixed to the substrate by another method, such as by adhesive. Indeed, the retaining members and the substrate could be formed integrally, such as by moulding.

Figure 5 shows a pre-compression apparatus for use with the apparatus of Figures 1-4. The schematic view is from above, looking down on a rod 210 of the wheel 200 of Figure 2. A pair of rotating brushes, 500, are located one either side of the rod 210. The brushes are rotating in an opposite sense so as to push a spring 100 located on the rod 210. As the brushes rotate they tend to compress the spring so that prior to the spring entering the compression zone 220 of the wheel (see Figure 2) the spring is already partly compressed.

In use, the pre-compression apparatus 500 is deployed immediately prior to the rod entering the compression zone 220. This is useful, particularly with longer springs, to help accommodate them within the opening of the compression zone. Figure 6 shows schematically an alternative embodiment of conveyor, in which retaining members 520 , of a different shape to those of the Figure 4 embodiment, are mounted on the substrate 410.

In particular, the retaining members 520 each comprise a mounting portion 530 for mounting to the substrate 420. A containment portion 540 comprises proximal and distal parts 540a and 540b define a space therebetween for receiving a coil spring 100 under compression. Slots 550a and 550b in the containment parts are aligned for receiving pushers (e.g. 120 in Figure 1) in a similar way as was described above in relation to the Figure 4 embodiment. Again, the slots are of sufficient length to accommodate pushers that are taller than the height of the compressed spring.

Again, the retaining members 520 may be secured to the substrate by suitable fixtures, as with the Figure 4 embodiment {though omitted from Figure 5) .

A first gap Gl between the distal containment parts 540a may be greater than a second gap G2 between the proximal containment parts 540b of adjacent retaining members. The first gap Gl is suitable for receiving a rod 210 of a spring depositing wheel 200 (Figure 2) . The second gap G2 can be smaller (as shown) or even substantially zero.

In this embodiment the spring is contained by an adjacent pair of retaining members alone and does not rest against the substrate. This provides a number of advantages: Firstly, the compressed spring is no longer urging the retaining member and the substrate apart, which is useful for heavier gauge, or taller springs. Secondly, as the substrate plays no part in the retention of the spring, a single substrate may be used with differently sized retaining members, or retaining members arranged with different spacing, to accommodate springs of different diameters. Also, insertion and removal of springs does not cause any wear on the substrate, only on the retaining members which can be easily replaced.

Furthermore, as the moving spring bears only against the proximal and distal containment parts of the blocks during insertion and removal, which parts are of a common material, there is no difference in the friction force experienced between the opposed ends of the spring, which could otherwise lead to an unintentional, or uncontrolled misalignment of the spring, and possibly a misfeed during pocketing.

In one embodiment (not shown) at least some of the springs are held in the retaining members in a splayed configuration, such that adjacent coils are at least partly axially offset, rather than aligned in a cylindrical shape. In this configuration, when the spring is displaced from the retaining members it will automatically seek to re-orientate itself so that its longitudinal axis is transverse, more preferably substantially 90 degrees, to that which it was when it ■ was held by the retaining member. This is useful in applications where it would otherwise be necessary to "turn" the spring in the pocket, to achieve the desired pocketing configuration.

To achieve the splayed configuration one end of the spring may be at least partly or temporarily restrained or slowed with respect to the other as the spring is being inserted into the retaining member.

Whilst the example described above is concerned with the transportation of springs, it will be understood by those skilled in the art that such transportation apparatus and method may be used to transport other articles.

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.