WO2002070378A1

WO2002070378A1 - Chain conveyor assemblies

Info

Publication number: WO2002070378A1
Application number: PCT/GB2002/000864
Authority: WO
Inventors: Craig Allan Hall; Ian Peter Lilley; Andrew John Warn
Original assignee: Apv Systems Limited
Priority date: 2001-03-02
Filing date: 2002-03-01
Publication date: 2002-09-12
Also published as: GB0105293D0

Abstract

According to the present invention there is provided a conveyor assembly (1) of the kind in which a chain (2) is constrained to follow a closed-loop track, and the chain carries a series of elongate support frames (5) extending transversely of the chain (2). Each support frame (5) comprises an elongate, substantially horizontal wire grid (7, 8, 8') carrying substantially vertical end plates (12), portions of adjacent support frames (5) remote from the chain (2) being so arranged as to overlap with one another in the vertical direction, at least throughout that part of the path of the conveyor in which the conveyor in use supports a load to restrict tilting of the frames (5) relative to one another about the local axis of the chain (2). The elongate end plates(12) can be stepped (16) as viewed in plan such that one end of one end plate (12) overlaps with the end of the adjacent end plate (12). This overlap can help to control the smooth flow of trays on the conveyor.

Description

CHAIN CONVEYOR ASSEMBLIES

This invention relates to chain conveyor assemblies of the kind in which a chain is constrained to follow a closed-loop track, and the chain carries a series of elongate support frames extending transversely of the chain, the central axes of the frames being spaced apart along the chain. Such a conveyor assembly will be referred to hereinafter as a 'conveyor of the kind set forth' .

Conveyors of the kind set forth are commonly used in baking ovens, provers and the like for conveying baking trays through an oven or prover of large volume, and to provide an adequate time of exposure to the oven atmosphere. The chain and associated support frames are commonly caused to follow an extensive loop, which often comprises a helix or figure of eight sections. It is important that trays or other items supported by the support frames are adequately supported and guided through the curves of the loop, and on entry to and exit from such curves, otherwise the trays may fall from the conveyor during part of their journey.

Typical prior art conveyors of the kind set forth have been manufactured and sold for many years by APN Baker under the name Lanham^®. Such conveyors employ support frames in the form of an elongate wire grid carrying vertical end plates. Although such conveyors perform well, on occasion there can be tendency in some circumstances for the grids to slew, which can result in abnormally large gaps being created between the end regions of adjacent grids with the associated risk that a tray may fall through the gap. Such grids generally have to be supported towards their ends by fixed elongate guide strips which follow the path of the conveyor, in order to reduce any tendency of the grids to tilt about the axis of the chain. Any such tilting can allow a tray to over-ride the conveyor on a curve, leading to possible falling of the tray.

The present invention stems from some work aimed at improving the stability and control of the support frames as they follow a circuitous path.

A first aspect of the invention is concerned with reducing the tendency of the support frames to tilt about the axis of the chain.

According to the first aspect of the present invention there is provided a conveyor assembly of the kind in which a chain is constrained to follow a closed-loop track, and the chain carries a series of elongate support frames extending transversely of the chain, characterised in that each support frame, as viewed with the local axis of the chain horizontal, comprises an elongate, substantially horizontal wire grid carrying substantially vertical end plates, portions of adjacent support frames remote from the chain being so arranged as to overlap with one another in the vertical direction, at least throughout that part of the path of the conveyor in which the conveyor in use supports a load, in order to restrict tilting of the frames relative to one another about the local axis of the chain.

The provision of such overlapping portions of adjacent support frames can make it unnecessary to provide auxiliary guide strips running parallel to the chain paths beneath the path of the support frames. Since such guide strips generally need to be constructed to follow the major portion of the path of the conveyor, the ability to dispense with the guide strips can lead to significant simplification and cost reduction of the conveyor assembly. The overlapping portions of the adjacent support frames are preferably constituted by, firstly, an end portion of a substantially vertical end plate of one support frame and, secondly, a bar carried by the respectively adjacent support frame, said bar extending substantially normal to the plane of the respective end plate.

Preferably each of said end plates extends over the bar of the adjacent support frame and is closely spaced therefrom such that when the frame carrying the bar begins to tilt to bring the bar into engagement with the underside of the end plate of the adjacent frame end, further tilting is inhibited.

According to a second aspect of the invention there is provided a conveyor assembly of the kind in which a chain is constrained to follow a closed-loop track, and the chain carries a series of elongate support frames extending transversely of the chain, characterised in that each support frame, as viewed with the local axis of the chain horizontal, comprises an elongate, substantially horizontal wire grid and is provided at the opposite ends thereof with an elongate end plate extending generally parallel to the chain and in a substantially vertical plane, the end plates being stepped as viewed in plan such that one end of one end plate overlaps with the end of the adjacent end plate.

This overlap can help to control the smooth flow of trays on the conveyor.

Preferably complementary abutment means is provided on the overlapping end plates to restrict the amount by which the overlapping portions can concertina together in the axial direction of the chain. The abutments can help to control slewing of the support frames.

Preferably one of the complementary abutments comprises the extremity of one end plate, and the other abutment is a lug projecting from the adjacent end plate at said step.

A prior art conveyor assembly and a conveyor assembly in accordance with the various aspects of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a plan view of part of a prior art conveyor showing how, on a bend, a corner of a tray can become positioned between end plates of the support frames,

Figure 2 is a perspective view of a chain link unit and single support frame supported thereby of a conveyor assembly in accordance with the invention,

Figure 3 is a plan view of the support frame of Figure 2

Figure 4 is an end view of the support frame looking in the direction of the arrow A in Figure 3 ,

Figure 5 is a plan view of part of the path of the inventive conveyor and showing the relative positions of the support frames whilst the frames are being carried around a bend,

Figure 6 is an enlargement of part of Figure 5,

Figure 7 is a side elevation of one of the support frame end plates of the inventive conveyor, Figure 8 is a plan of the plate of Figure 7, and

Figure 9 is a partial cross-sectional view on the line 9-9 of Figure 5 showing in side elevation two overlapped end plates.

Figure 1 shows how on a sharp bend of a prior art chain conveyor the corner of a large baking tray B can project into the gap between end plates E on support frames S. The corners of such trays can on occasion become trapped between the adjacent plates E when the support frames S then enter a straight section of the conveyor run.

Referring now to Figure 2, this shows one conveyor unit 1 of a chain conveyor in accordance with the invention and suitable for use in a baking or proving oven. The conveyor unit 1 comprises a central chain link unit 2 adapted to run, in known manner, in a box-section chain guide rail, not shown, provided with a slotted upper surface through which projects a pendant plate 6. The chain link unit 2 comprises, in known manner, a pair of chain rollers 3 to support vertical thrusts applied to the chain unit, and a guide roller 4 to guide the chain around the inside face of the bends. Roller 4 also limits the tilt of the chain along straight sections of the conveyor run in the event of an offset load being carried.

An elongate support frame 5 is rigidly attached to the upper end of pendant plate 6 and comprises a pair of parallel main frame rods 7, a zigzag rod 8 and bridging rods 8 ' , all welded together to form an elongate wire grid. The attachment of pendant plate 6 to the support frame 5 is by way of brackets 9 welded to the main frame rods 7, and to a clamp 11 secured to the pendant plate 6 by nut 10. Stepped elongate end plates 12 are welded to the opposite ends of the main frame rods 7, the plates 12 extending in vertical planes, and each comprising a forwardly projecting toe 13 and a trailing heel 14.

When the support frame 5 is viewed with the local axis of the chain link unit 2 substantially horizontal, the elongate wire grid of each support frame 5 is substantially horizontal and the end plates 12 are substantially vertical.

A respective L-shaped tilting control bar 15 is welded at the rear end thereof to the lower corner of the respective heel 14, and at the front end thereof to the trailing main frame bar 7, the tilting control bar 15 is extending horizontally into the space defined inwardly of a stepped portion 16 of plate 12 and the respective heel 14.

The horizontal limb 18 of each tilting control bar 15, as shown in Figure 9, lies closely beneath, but spaced from, the under-edge 19 of the toe 13 such that if the leading conveyor unit 1 tilts by more than a predetermined amount about the local axis of the chain, so as to lift the adjacent (right-hand in Figure 9) end plate 12, the bar limb 18 will engage with the under-edge 19 of toe 13 to restrict the relative tilting of the conveyor units 1 about the local axis of the chain. The vertical spacing of limb 18 from under-edge 19 is desirable to permit the conveyor to pass over any ramps in the conveyor run.

Similarly, if the adjacent end of the left-hand conveyor unit in Figure 9 were to rise due to tilting about the local chain axis, then the bar limb 18 of the left-hand conveyor unit in Figure 9 would engage with the toe 13 of the following conveyor unit, not shown. Thus tilting of one conveyor unit relative to adjacent conveyor units is restricted for both directions of tilting about the local axis of the chain conveyor, without the need for any guide strips beneath the outer ends of the conveyor units.

In order to assist in guiding and retaining the side edges of trays, tins or other articles on the conveyor whilst the conveyor executes a bend, and on entry to and exit from a bend, the stepped end plates overlap with one another, as viewed in plan, as shown in Figure 5, the free ends of the toes 13 of one conveyor unit fitting between the heels 14 of the adjacent conveyor unit. Thus, the overlapping end plates 12 form a continuous barrier to sideways movement of the trays along both margins of the conveyor.

In order to limit tilting of the adjacent conveyor units 1 relative to one another about the vertical axes of pendant plates 6, the end plates 12 are each provided with a lug 20 in the form of a vertical plate extending outwardly of the end plate 12 from the connection between the respective stepped portion 16 and the respective toe 13.

As shown in Figures 5 and 6, on the inside of tight bends in the conveyor path, the free ends of the heels 14 closely approach the lugs 20 and will engage with the lugs 20 if the individual conveyor units 1 begin to pivot excessively about the vertical axis of the associated pendant plate 6. Thus, the lugs 20 will control any tendency of the conveyor units 1 to slew, that is, to pivot excessively relative to one another about the vertical axes of the pendant plates 6.

It will be appreciated that the provision of lugs 20 on both side plates 12 of each conveyor unit provides protection against excessive twisting of the grids for both right-hand and left-hand bends, and is therefore suitable for figure-of-eight configurations of conveyor. For some simpler conveyor layouts, however, involving single or double ovals only for example, where curves in only one direction are provided, it would suffice to provide such lugs 20 on only one side plate 12 of each conveyor unit.

Claims

1. A conveyor assembly (1) of the kind in which a chain (2) is constrained to follow a closed-loop track, and the chain (2) carries a series of elongate support frames (5) extending transversely of the chain (2), characterised in that each support frame (5), as viewed with the local axis of the chain horizontal, comprises an elongate, substantially horizontal wire grid (7, 8, 8') carrying substantially vertical end plates (12) , portions of adjacent support frames (5) remote from the chain (2) being so arranged as to overlap with one another in the vertical direction, at least throughout that part of the path of the conveyor (1) in which the conveyor (1) in use supports a load, in order to restrict tilting of the frames (5) relative to one another about the local axis of the chain (2) .

2. A conveyor assembly (1) as claimed in claim 1 in which the overlapping portions of the adjacent support frames (5) are constituted by, firstly, an end portion (13) of a substantially vertical end plate (12) of one support frame (5) and, secondly, a bar (15) carried by the respectively adjacent support frame (5) , said bar (15) extending substantially normal to the plane of the respective end plate (12) .

3. A conveyor assembly (1) as claimed in claim 2 in which each of said end plates (12) extends over the bar (15) of the adjacent support frame (5) and is closely spaced therefrom such that when the frame (5) carrying the bar (15) begins to tilt to bring the bar (15) into engagement with the underside of the end plate (12) of the adjacent frame end, further tilting is inhibited.

4. A conveyor assembly (1) of the kind in which a chain (2) is constrained to follow a closed-loop track, and the chain (2) carries a series of elongate support frames (5) extending transversely of the chain (2) , characterised in that each support frame (5) , as viewed with the local axis of the chain horizontal, comprises an elongate, substantially horizontal wire grid (7, 8, 8') and is provided at the opposite ends thereof with an elongate end plate (12) extending generally parallel to the chain (2) and in a substantially vertical plane, the end plates (12) being stepped (16) as viewed in plan such that one end of one end plate (12) overlaps with the end of the adjacent end plate (12) .

5. A conveyor assembly (1) as claimed in claim 4 in which complementary abutment means (14, 20) is provided on the overlapping end plates (12) to restrict the amount by which the overlapping portions can concertina together in the axial direction of the chain (2) .

6. A conveyor assembly (1) as claimed in claim 5 in which one of the complementary abutments (14, 20) comprises the extremity (14) of one end plate (12) , and the other abutment (20) is a lug projecting from the adjacent end plate (12) at said step (16) .

7. A conveyor assembly (1) substantially as described herein with reference to the accompanying drawings.