A TRANSPORT CHAIN
The present invention relates to a transport chain of the kind that is used in carrying or transporting objects or material.
A conventional roller chain is shown in figure 1. It comprises pairs of opposed inner link plates 1 interspersed along the length of the chain by pairs of opposed outer link plates 2. Each outer link plate 2 overlies the adjacent ends of neighbouring inner link plates 1 such that an aperture at each end of the outer link plate 2 is aligned with an corresponding aperture in the end of the underlying inner link plate 1. The inner and outer link plates 1, 2 are interconnected on opposite sides of the chain by means of a pin 3 that passes through the aligned apertures on each side. The pin 3 is fixed at each end to the opposed outer link plate 2 but is pivotal relative to the inner link plates 1 within a bush (hidden) that extends between opposed apertures in the inner link plates 1 and on which is supported a roller 4.
Such a chain is modified when used in transport applications so that a clean transport surface is provided. The surface must be disposed such that it is not at risk of contamination from chain grease or other lubricant. An example of a prior art transport chain is shown in figure 2. The inner link plates 1 of the conventional chain have been modified in such a way that they are joined at their upper edges by an integral perpendicular bridging member 5 that presents an upwardly facing transport surface 6. The upper surface of the bridging member 5 is fitted with a polymer block 7.
An alternative prior art transport chain is shown in figure 3. In this design a plastic plate 8 is inserted between the inner and outer link plates 1, 2. The edges 9 of the plastic plate project beyond those of the link plates 1, 2 and provide a surface on which objects can be supported across the width of the chain.
A disadvantage of the prior art embodiments is that they do not permit retrospective fitting of a transport surface to a conventional roller chain.
Moreover, if the surface material is damaged repair is made difficult in that the chain has to be almost entirely unassembled to replace the damaged part.
It is an object of the present invention to obviate or mitigate the aforesaid disadvantages.
According to the present invention there is provided a transport chain comprising a plurality of interconnected link assemblies that are pivotal relative to one another, wherein there is provided at least one support member that is releasably connectable to an outer portion of each link assembly, each support member having a transport platform for the carrying of material to be transported.
The transport platform may be integral with or releasably connectable to the support member. In the latter case the support member may be provided with a slot which receives part of the transport platform. This slot may be V- shaped and defined by upstanding walls of the support member.
A support member may be provided on each side of a given link assembly and opposed support members may be interconnected by a joining member.
The transport platform may have a single surface or may comprise a plurality of surface portions. Preferably the platform is an elongate member that extends along the length of the chain and longitudinally flexible or alternatively may have discontinuities along its length. The transport surface is preferably planar but may have upstanding edges for retaining the material being transported.
Preferably each link assembly comprises inner and outer link plates that are pivotally interconnected by a pin. Each support member preferably clips over the outer link and may clip over an end of a pin that projects from the outer link.
Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Figure 1 is a sectioned view through a conventional roller chain of the prior art;
Figures 2 and 3 are sectioned views through prior art transport chains;
Figure 4 is a sectioned view through a first embodiment of a transport chain according to the present invention;
Figure 4a is a plan view of the transport chain of figure 4;
Figures 4b to 4d show different embodiments of a transport surface which forms part of the present invention;
Figure 5 is a side view of the transport chain of figure 4;
Figure 6 is a side view of a second embodiment of a transport chain of the present invention; and
Figure 6a shows a sectioned view through a transport chain of the present invention with a support member on only one side.
Referring now to the drawings, figures 4, 4a and 5 show a transport chain comprising a conventional roller chain (indicated generally by reference numeral 10) to which is attached a transport platform 12.
The conventional roller chain 10 comprises pairs of opposed inner link plates 13 interspersed along the length of the chain by pairs of opposed outer link plates 14. Each outer link plate 14 overlies the adjacent ends of neighbouring inner link plates 13 such that an aperture at each end of the outer link plate 14 is aligned with an corresponding aperture in the end of the underlying inner link plate 13. The inner and outer link plates 13, 14 are interconnected on opposite sides of the chain 10 by means of a pin 15 that passes through the aligned apertures on each side. The pin 15 is fixed at each end to the opposed outer link plate 14 but is pivotal relative to the inner link plates 13 within a bush 16 that extends between opposed apertures in the inner link plates 3. Freely supported on the bush 16 is a cylindrical roller 17.
The transport platform 12 comprises a pair of spaced elongate strips 18 that are T-shaped in cross-section with upper planar surfaces 19 for supporting the transported material and depending stems 20 by which they are secured to the chain 10. The elongate strips 18 are disposed above upper edges of the link plates 13, 14 and are connected to the chain 10 by a supporting clip 21 that fits
over upper and side face 22, 23 of the chain 1. The clip 21 comprises a central bridge member 24 that traverses the width of the chain link and interconnects a pair of laterally spaced V-shaped slots 25 that are defined by upstanding walls 26 which extend along the length of the chain 10. The slots 25 are designed to receive the stem 20 of the transport platform 12 in a secure engagement. Outboard of the V-shaped slots 25 there are provided depending walls 27 which flank the outer link plates 14 on each side of the chain 10. Each depending wall 27 has a circular recess 28 that is designed to engage with the end of the pin 15 that protrudes from the outer link plate 14. The V-shaped slots 25 are supported directly above the upper edge of the inner and outer link plates 13, 14 and are each designed to receive releasably a transport platform 12.
The supporting clip 21 and the transport platform 12 are manufactured from, for example, an extruded polymer which has resilient characteristics so that it engages securely with the chain. The walls 26 of the V-shaped slots 25 have in-turned upper edges 29 that snap-fit in an undercut 30 of the stem 20 of the transport platform 12.
In order that the chain can pass over a drive sprocket the transport platform is designed to be flexible in a longitudinal direction or, alternatively, is provided with discontinuities along its length.
The transport platform 12 for the chain of figures 4 and 4a is shown in isolation in figure 4b and alternative embodiments of the transport platform 12 are shown in figures 4c and 4d. In the embodiment of figure 4c the platform 12' is a single piece extrusion that extends across the entire width of the chain so as to provide a greater surface area for supporting the material. A similar design is shown in figure 4d but with edges 30 of the platform 12" upturned so as to assist in the retention of loose material on the platform during transportation.
In the embodiment of figures 4 and 5 each link is fitted with two clips 21 each of which engages with the pins 15. In an alternative design shown in figure 6 a single clip 21 is provided for each link and the depending walls 27 engage with a central portion of the outer link 14.
If appropriate the chain may be provided with a transport platform 12 and supporting clip 21 surface on one side only as shown in figure 6a. This design could use the supporting clip design of figure 5 or figure 6.
It will be appreciated that numerous modifications to the above described design may be made without departing from the scope of the invention as defined in the appended claims. For example the shape of the upper surface of the transport platform may take any shape that is appropriate for the material being transported. Moreover, the transport platform may be made integral with the supporting clip.
In an embodiment (not shown) the chain may have a continuous extruded rubber tube that extends along its length and projects from a side face of the clips. The tube abuts an adjacent wall or guard and enables a side load to be absorbed without chain deflection. Alternatively, each clip may carry a ball which is housed in a socket, the ball and socket performing the same function as the tube described above. These designs would also enable the chain to run around mild bends in a controlled manner.