GB2323766A

GB2323766A - Seed cleaning machine

Info

Publication number: GB2323766A
Application number: GB9706976A
Authority: GB
Inventors: John Michael Cummings; Geoffrey Ashley Greenwood; Patrick Boughey
Original assignee: COCKSEDGE ENG Ltd
Current assignee: COCKSEDGE ENG Ltd
Priority date: 1997-04-05
Filing date: 1997-04-05
Publication date: 1998-10-07
Also published as: GB9706976D0

Abstract

A seed cleaning machine comprising a passageway (22) defined between a conical, static mesh screen (24) and an inner conical, rotating, abrasive cone (26), and dust extraction means passing a flow of cold air into the passageway in contraflow to the seeds. The cone (26) may have lands (36) where a reduced gap is produced with the screen (24). The seeds may subsequently pass through a second passageway 28 between a mesh screen 30 and a rotating abrasive disc 32.

Description

Seed Cleaning Machine This invention relates to a seed cleaning machine.

A seed rubbing machine is known in which seeds to be cleaned are rubbed between a rubber pad and a rotating abrasive disc. Seed dust and rubbed seeds exit from the machine at a common outlet and for further processing prior to pelleting the seeds require to be polished in another machine.

According to the invention, there is provided a seed cleaning machine comprising a passageway along which the seeds are passed between two surfaces at least one of which is an abrasive surface and at least one of which is a moving surface, and dust extraction means whereby a flow of air is passed into the passageway in contraflow to the seeds.

Preferably, the passageway is defined between a static mesh screen and a rotating member having at least in part an abrasive surface. Conveniently, the screen may be conical and surround a rotating, abrasive cone. The cone angles of the screen and rotating cone are preferably the same. The conical surface of the rotating cone preferably has at least one annular land at which a gap of reduced thickness is created with the mesh screen. At least three such lands are preferably provided. At least the surface(s) of the land or lands parallel to the mesh screen are abrasive.

The seeds preferably fall under gravity from a product inlet, through the conical annular passageway formed between the conical, static screen and the rotating abrasive cone to a product outlet. Preferably, the product outlet serves as the inlet for the air passing in contraflow into the passageway, whilst the air outlet, which is connected to a suction fan, is adjacent the product inlet. This air outlet receives air which emerges with entrained dust through the conical mesh screen.

Preferably, immediately after passing through the said conical passageway, the seeds are passed through a second passageway before passing to the product outlet. The second passageway is preferably formed between an annular, static mesh screen, preferably contiguous with the conical, first mesh screen, and an annular, rotating, abrasive disc. Such an arrangement enables the seeds to be both rubbed and polished, thereby to be ready for pelleting on emergence from the product outlet.

The air outlet also receives air which passes through the annular, static mesh screen, whilst the annular abrasive disc is preferably slotted to assist entry of air into the second passageway, and create turbulence amongst the seeds passing through this passageway.

The air which enters the machine at the product outlet is cold, and may be specially cooled for the purpose, so that the cold air passing in contraflow to the seeds tends to keep the seeds cool, which is important to maintain the integrity and the germination properties of the seeds.

The invention is applicable to a variety of seeds including peppercorns, brassica and marrow seeds, but finds especially useful application in the cleaning of sugar beet seeds. in order to provide optimum cleaning for various types and varieties of seeds, the gap sizes of the first and second passageways are adjustable, preferably independently, and the speeds of rotation of the abrasive rotating cone and of the abrasive annular disc are preferably also adjustable.

A common drive motor may drive both the rotating cone and the rotating disc, preferably in unison.

The invention is further described with reference to the accompanying drawings, in which: Figure 1 is a pictorial view of the seed cleaning machine; Figure 2 is a cross-sectional view through the machine in elevation; Figure 3 shows a rotary abrasive disc in plan view; and Figure 4 shows an adjustment means for the mesh screens.

The machine shown in Figure 1 stands about 1'h metres high and has an inlet 10 for seeds at the top, adjacent an air outlet 12 through which air is drawn out by a fan (not shown). Near the bottom the machine has a clean seed outlet 14, which also serves as a cold air intake. The machine also has an inspection and clean-out hatch 16, a control panel 18, adjustment means 20 for the mesh screens, as later described, and a motor vent 21.

The interior of the machine is shown in Figure 2. From the seed inlet 10, the seeds fall along a conical annular passageway 22 formed between a conical mesh screen 24 and an inner rotary cone 26. The seeds emerge from this first passageway 22 to pass along a second passageway 28 formed between an annular mesh screen 30, contiguous with the conical mesh screen 24, and a rotary annular disc 32. The second passageway 28 is also conical, but of a much shallower angle than the first passageway 22. On emergence from the second passageway 28, the seeds fall on to a ramp 34 leading to the seed outlet 14. Cold air is drawn in, in contraflow into the second passageway 28, and thereafter into the first passageway 22, and emerges, together with entrained dust (seed rubbings), through the mesh screens 24 and 30 into a chamber 36 communicating with the fan-connected air outlet 12.

The rotary cone 26 has lands 36 where a reduced gap is produced with the static conical screen 24. The flat surfaces of these lands 36 facing the mesh screen 24 are abrasive, for example coated with carborundum. In use, as the seeds fall in the passageway 22 between the conical mesh screen and rotating abrasive cone, they are subjected to a rubbing and tumbling pressure, which is of pulsating nature due to presence of the abrasive lands 36, and which has been found to be extremely effective in rubbing the sharp corners from the husks of seeds, such as generally star-shaped sugar beet seeds.

The seeds then pass down the second passageway 28, where the seeds are subject to further rubbing and to polishing between the annular mesh screen and the rotating disc, assisted by the passage of air into the passageway through slanted slots 38 provided in the rotary disc 32 (see Figure 3), which is also abrasively coated. The air entering through these slots 38 creates turbulence in the second passageway 28 which has been found to be extremely effective in assisting the final cleaning of the seeds and polishing thereof to a near spherical shape advantageous for pelleting (encapsulating with materials for assisting germination, resisting insects, etc.).

For sugar beet seeds especially, a mesh size convenient for both the conical screen 24 and the annular screen 30 has been found to lie in 2 mm holes, with 3 mm staggered pitch, providing an open area through each screen of 40 per cent of the total area. The gap size for the conical passageway 22, at the lands 36, is conveniently adjustable between 6 mm and 12 mm, and the gap size of the second passageway is conveniently adjustable between 0 and 12 mm.

The means of screen adjustment is shown in Figure 4. Briefly, it can be seen that the screwthread 38 enables the conical mesh screen 24 to be raised and lowered vertically, whereby to adjust the gap size at the first passageway 22, whilst the screwthread 40 enables the annular screen 30 to be independently raised and lowered vertically, whereby to adjust the gap size at the second passageway 28. It will be noted that the contiguous nature of the abutment of the two screens 24, 30 is maintained in all positions of adjustment, possibly ensured by a suitable sliding seal to prevent passage of seeds between the adjacent edges of the two screens. The rotary control elements 42, 43 by which the respective screens are adjustable are accessible from the machine exterior.

The rotary cone 26 and rotary disc 32 are drivable in rotation by an electric motor 44 having an output shaft 45 centred in bearings 46 positioned immediately below the rotary disc. The motor is controllable from a control panel 48 having start/stop and speed controls (not shown) operative via an inverter 50.

In the above-described machine, the flow of cold air in contraflow to the seeds being cleaned is important not only to enable dust extraction, but also to cool the seeds undergoing treatment.

Claims

Ams

1. A seed cleaning machine comprising a passageway along which the seeds are passed between two surfaces at least one of which is an abrasive surface and at least one of which is a moving surface, and dust extraction means for passing a flow of air into the passageway in contraflow to the seeds.

2. A machine according to claim 1, wherein the passageway is defined between a static mesh screen and a rotating member having at least in part an abrasive surface.

3. A machine according to claim 2, wherein the screen may be conical and surround a rotating, abrasive cone.

4. A machine according to claim 3, wherein the cone angles of the screen and rotating cone are the same.

5. A machine according to claim 4, wherein the conical surface of the rotating cone preferably has at least one annular land at which a gap of reduced thickness is created with the mesh screen.

6. A machine according to claim 5, wherein at least three such lands are provided.

7. A machine according to claim 5 or claim 6, wherein at least the surfaces of the land or lands parallel to the mesh screen are abrasive.

8. A machine according to claim 3 or any claim appendant thereto, wherein the seeds fall under gravity from a product inlet, through the conical annular passageway formed between the conical, static screen and the rotating abrasive cone to a product outlet.

9. A machine according to claim 8, wherein the product outlet serves as the inlet for the air passing in contraflow into the passageway.

10. A machine according to claim 8 or claim 9, wherein the air outlet, which is connected to a suction fan, is adjacent the product inlet.

11. A machine according to claim 10, wherein the air outlet receives air whcih emerges with entrained dust through the conical mesh screen.

12. A machine according to claim 8 or any claim appendant thereto, wherein, immediately after passing through the said conical passageway, the seeds are passed through a second passageway before passing to the product outlet.

13. A machine according to claim 12, wherein the second passageway is formed between an annular, static mesh screen, preferably contiguous with the conical, first mesh screen, and an annular, rotating, abrasive disc.

14. A machine according to claim 9 or any claim appendant thereto, wherein the air outlet also receives air which passes through the annular, static mesh screen.

15. A machine according to claim 14, wherein the annular abrasive disc is slotted to assist entry of air into the second passageway, and create turbulence amongst the seeds passing through this passageway.

16. A machine according to claim 9 or any claim appendant thereto, wherein the air which enters the machine at the product outlet is cooled air, so that the air passing in contraflow to the seeds tends to keep the seeds cool.

17. A machine according to any of claims I to 16, applied to the cleaning of peppercorns, brassica or marrow seeds or sugar beet seeds.

18. A machine according to any of daims 12 to 17, wherein, in order to provide optimum cleaning for various types and varieties of seeds, the gap sizes of the first and second passageways are adjustable.

19. A machine according to claim 18, in which the gap sizes are independently adjustable.

20. A machine according to claim 19, wherein the speeds of rotation of the abrasive rotating cone and of the abrasive annular disc are also adjustable.

21. A machine according to claim 13 or any claim appendant thereto, wherein a common drive motor drives both the rotating cone and the rotating disc, preferably in unison.

22. A seed cleaning machine substantially as hereinbefore described with reference to the accompanying drawings.