GB2201390A

GB2201390A - Conveyor offtake arrangement

Info

Publication number: GB2201390A
Application number: GB08704259A
Authority: GB
Inventors: Ernest George Benfield
Original assignee: CARIER
Current assignee: CARIER
Priority date: 1987-02-24
Filing date: 1987-02-24
Publication date: 1988-09-01
Anticipated expiration: 2007-02-24
Also published as: GB8704259D0; GB2201390B

Abstract

A conveyor has a screw 3, of chain and flight conveyor, acting in a fixed trough or pipe, and an offtake arrangement is provided in a trough length 5, which may be part of the conveyor trough or may be in extension of the conveyor trough. Means 8, 9 is provided for retracting a part 6 of the lower part of the trough length 5 to provide a gravity offtake, so that the offtake opening is closed by the readvancement of the part 6 so as effectively to restore the shape of the trough, whereby no dead spots, pockets or wells are left to hold residues of material. The lower part 6 of the trough length 5 is retractable and advanceable in two portions, one to and from each side, conveniently simultaneously in opposite directions by a common drive means which is shown as a lead screw 9 having lengths 9a, 9b with oppositely handed threads. Limit switches may be provided to limit the movement of the lower part 6 of the trough length 5. The retraction and advancing may alternatively be performed by pneumatic, hydraulic or electric drive means. <IMAGE>

Description

CONVEYOR OFFTAKE ARRANGEMENT This invention relates to offtake arrangements for conveyors, particularly conveyors incorporating a movable conveying device, such as a screw or a series of flights, operating in a fixed trough.

Such conveyors conventionally have a U or channel section trough, which may be closed by a top cover to form a pipe, and intermediate offtakes incorporate a slide operating usually laterally of the direction of the conveyor. Particularly with the U shape trough, which is conventional and necessary with a screw conveyor, the slide forms a well or dead-spot in which a residue of material may be collected. Such a residue is in some cases acceptable, but there are frequent instances when cross -contamination is totally unacceptable, which thus preclude the use of the conventional screw conveyor. Examples are animal food supplements, which should not be mixed with the wrong food, and chemicals such as a selective weed-killer or seed dressing, which should not be mixed with the wrong seed or fertiliser.

In what follows the term "trough" is intended to be used as including a closed top trough, forming a pipe.

In accordance with a first aspect of the present invention, there is provided an offtake arrangement for a conveyor having a moving conveyor device acting in a fixed trough, comprising a trough length arranged or arrangeable in extension of the conveyor trough to form a continuous trough therewith, and means for retracting all or part of the lower part of the trough length to provide a gravity offtake in the base of the continuous trough.

By this means, the offtake opening is closed by the re -advancement of the trough length so as effectively to restore the shape of the trough, whereby no dead spots, pockets or wells are left to hold residues of material.

Preferably, the lower part of the trough length is retractable and advanceable in two portions, one to and from each side, conveniently simultaneously in opposite directions by a common drive means, which may be a lead screw having lengths with oppositely handed threads.

Alternatively, the lower part of the trough length is retractable by a pneumatic drive means.

Limit switches may be provided to limit the movement of the lower part of the trough length, and also to provide an indication of the status, open or closed, of the offtake.

According to a second aspect of the invention, there is provided a conveyor having a moving conveyor device operating in a fixed trough and further comprising an offtake arrangement according to the invention as set forth above.

The invention will be further described with reference to the accompanying diagrammatic drawings of a presently preferred embodiment, and in which: Figure 1 is an elevation of a conveyor trough with a screw and an intermediate offtake; Figure 2 is a transverse section showing the offtake in open position; Figure 3 is-a section similar to figure 2 and showing the offtake in closed position; and Figure 4 is a perspective view of an offtáke in partly open position.

Figure 1 shows a-static conveyor trough 1 with an internal screw 2 with a helical flight 3 mounted for rotation to convey granular material along the trough 1. The position of an intermediate gravity offtake arrangement is indicated at 4. Any given conveyor may have one or a plurality of such offtake arrangements.

Turning now to figures 2 to 4, the offtake arrangement is shown as comprising a length 5 of trough to be interposed between matching lengths of the trough 1 so as to form a continuous trough therewith. Partway along the length 5 two matching sections 6 are arranged to be retracted laterally in opposite directions to provide an opening 7 for gravity offtake, as indicated in figure 2. In this figure, the balance of the base of the length is shown at 5a. Figure 3 shows the sections 6 in the closed position.

In practice, it is more usual for gravity offtakes to be constructed within a length of trough or pipe, and not interposed between two lengths as shown, and the invention also extends to conveyors with this arrangement, and in such a case the sections 6 would be located appropriately in the trough or pipe itself.

The sections 6 are illustrated as carrying captive nuts 8 co -operating with a common lead screw 9 driven, via a transmission 11, from an electric motor 12. The lead screw 9 has lengths 9a and 9b with oppositely handed threads so as to drive the nuts 8 and sections 6 in opposite directions.

Figure 4 shows limit switches 13, operable by adjustable -abutments 14, to limit the movement of the sections 6, and these may also be used to give an indication as to whether the offtake is open or closed.

It will be appreciated that instead of the electro -mechanical drive-illustr,ated, a manual, pneumatic or hydraulic drive may be used if required. A further alternative is the use of an electro linear actuator.

Various other modifications may be made within the scope of the invention as defined in the appended claims. For example, instead of a screw conveyor operating in a U shaped trough, the trough may be closed at the top. Also, the invention may be applied to a conveyor of the chain and flight type, and in such a case, the flights would normally run in a U shaped trough, and a return run for the chain could be provided above the trough, between the trough and an upper closure therefor.

Claims

1. An offtake arrangement for a conveyor having a moving conveyor device acting in a fixed trough, comprising a trough length arranged or arrangeable in extension of the conveyor trough to form a continuous trough therewith, and means for retracting all or part of the lower part of the trough length to provide a gravity offtake in the base of the continuous trough.

2. An offtake arrangement as claimed in claim 1, wherein the lower part of the trough length is retractable in two portions, one to each side.

3. An offtake arrangement as claimed in claim 2, wherein the two portions are simultaneously retractable and advanceable in opposite directions by a common drive means.

4. An offtake arrangement as claimed in claim 3, in which the common drive means comprises a leadl screw having lengths with oppositely handed threads.

5. An offtake arrangement as claimed in claim 1 or 2, in which the lower part of the trough length is retractable and advanceable by a pneumatic drive means.

6. An offtake arrangement as claimed in claim 1 or 2, in which the lower part of the trough length is retractable and advanceable by an electro linear actuator.

7. An offtake arrangement as claimed in claim 1 or 2, in which the lower part of the trough length is retractable and advanceable by a manually actuated drive.

8. An offtake arrangement as claimed in claim 1 or 2, in which the lower part of the trough length is retractable and advanceable by a hydraulic drive means.

9. An offtake arrangement as claimed in any of the preceding claims, comprising limit switches to limit the movement of the lower part of the trough length.

10. An offtake arrangement for a conveyor, substantially as hereinbefore described with reference to the accompnaying drawings.

11. A conveyor having a. moving conveyor device and a fixed trough and further comprising an offtake arrangement as claimed in any of the preceding claims.