GB2213079A

GB2213079A - Grading/sorting grain or seed

Info

Publication number: GB2213079A
Application number: GB8830294A
Authority: GB
Inventors: Roger John Drury
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-12-29
Filing date: 1988-12-28
Publication date: 1989-08-09
Anticipated expiration: 2008-12-28
Also published as: GB8830294D0; DK147890D0; GB2213079B; WO1989006166A1; AU2948489A; EP0394344A1; DK147890A

Abstract

Grains or seeds are projected each at the same velocity in a stream; the grain or seed is caught at a first or second catching site depending on the trajectory that it has followed. Grain/seed that has fallen at the first catching site is collected separately from that falling at the second catching site. The two catching sites may be separated by an adjustable divider to adjust the quality of grain/seed collected from the different catching sites. The grain/seed may be cleaned by an adjustable air flow directed counter to the path of the grain/seed. Optionally the apparatus may be adjustable to enable it to be used for a pre-cleaning run before the grain/seed is graded or sorted. Separation thus occurs on the basis of differences in specific gravity and may be employed to separate out grains which have commenced germination. In a practical embodiment of apparatus, grain or seed is supplied in a regulated stream to a rotary impeller (51, Fig. 2, not shown) that projects it into a free-flight chamber (61) having an adjustable divider (74). <IMAGE>

Description

METHOD AND APPARATUS FOR GRADING AND/OR SORTING SEED OR GRAIN Tfle present invention relates to the handling and grading of seed and/or grain and has as its chief object the division of a bulk of material, usually of one species or cultivar, into separate types or groupings which may differ from one another in their physical, chemical, biological or botanical properties.

Grain and seed has to reach a certain quality to be acceptable for some uses. This is currently checked by taking samples. In particular wheat has to be of a certain quality in order to be suitable for bread making. One aspect of the suitability is gauged by the "Hagberg" test in which a high "falling" number is preferred.In the case where samples are taken a few poor grains in a sample could affect the result of the test thus removing from use the bulK of possibly acceptable grain.

In a period of wet weather at harvest some grains will start to germinate in the standing crop before it is harvested. Even with no visible signs of sprouting the grain's starch content will start turning to malt and sugars as soon as germination commences. A small percentage of germinating grain (5% or more) renders a whole crop of milling wheat unsuitable for bread making. Affected grain is similar in size and appearance to good grain but the change in composition causes it to have a specific gravity of about 5% less. At present the only way of separating out this affected grain is by using a gravity seed cleaner which passes grain slowly over a vibrating table and/or fluidized bed. This process is costly, time consuming and, in practice, seldom used.

According to the present invention there is provided a method of grading and/or sorting grain or seed comprising the steps of projecting grains or seeds at the same speed and same angle in a stream, catching the grain/seed at first and second catching sites which are disposed in the path of the falling grain/seed, the second catching site being nearer to the projector than the first catching site; and collecting grain/seed that has fallen at the first catching site separately from the grain/seed that has fallen at the second catching site.

The invention also provides apparatus for grading and/or sorting seed or grain comprising a projector for projecting grains or seeds at the same speed and angle in a stream; first and second catching sites disposed in the path of falling grain/seed, the second catching site being nearer to the projector than the first catching site; and collecting chambers for collecting the grain/seed that has fallen at the first catching site separately from the grain/seed that has fallen at the second catching site.

The catching sites may actually catch the grain/seed physically, but alternatively they may just channel the yrain/seed to a collecting chamber located away from the catching site. The catching sites may lie on the floor, or alternatively may be angled to the horizontal depending on the angle of projection. Two or more projectors can be employed in parallel and in such a case the catching sites will forward the collected seed or grain on via a conveyor or conduit.

Advantageously the projector includes a variable speed impeller arranged to project grain or seed through an inclined chute. In practice it is found that the trajectory followed by each individual grain/seed will depend upon certain of its own physical properties, in particular its specific gravity. Grain/seed with a higher specific gravity will travel further. The two catching sites may be separated by a divider to collect high specific gravity seed or grain above the divider and lower specific gravity seed or grain below the divider. Preferably the divider is moveable to adjust the quality of.seed/grain collected in each part.

Preferably the parabolic trajectories followed by the grains/seeds are modified by a counter gas flow to slow them down. The lighter grains are more modified than the heavier and therefore drop out earlier so that the natural difference in trajectories taken up by different weight grains/seeds is amplified. The counter flow may additionally collect dust and chaff which is collected separately from the grain.

The invention will now be described, by way of example, with reference to the accompanying drawings in which, Figure 1 illustrates a simple device according to the invention, Figure 2 is a diagrammatic view in cross section of a grain pre-cleaner and separator according to the invention, Figure 3 shows detail of the separation chamber when the machine is being used for precleaning only and Figure 4 shows detail of the impeller blade and chamber.

Figure 1 shows a projector or discharge device 11 which projects a stream of grain or seed, each grain or seed being discharged at the same speed and angle upwardly towards a set of collecting containers or hoppers 12.

Although this device can be used for seed, hereafter we will refer to the operation in respect of grain.

The device may operate mechanically or pneumatically but the illustrated device operates by gravity. An accurately metered supply of grains is accurately fed down a long narrow feed tube (not shown) at an angle of approximately 350-450 to the vertical from which the grains move into a projection tube 14 which is angled at about 50 above or below the horizontal. The precise angle which provides the optimum performance has yet to be established but it is thought that 0 to 100 would be an acceptable range. It may be possible to incorporate an adjustable angle for the projection tube 14 to provide the most effective angle during use.

The projection of the grain is achieved by gravity possibly assisted by the force of grain accumulating above in the projection tube 14 and the feed tube. The grains are projected in a controlled stream with each grain leaving the tube at the same angle and speed. Depending on the individual properties of the grain, the projected grains will land a different distance from the tube 14 having followed a different trajectory.

A set of containers 12 arranged at catching sites across the range of distances from the projection tube 14 that might be expected will pick up all the grain, grain with similar properties falling into the same or adjacent containers. Thus the grain is sorted into type. The containers may either be adjacent to one another in a row on the horizontal, or the row may be angled to the horizontal as shown in the drawing with the lowest container being that nearest to the projector.

It is then possible to select the quality that is required and to use only the grain falling in the relevant containers. Alternatively all the grain can be used but can be priced differently.

The containers may be in the form of hoppers leading perhaps to a conveyor disposed below, or alternatively in the form of channels along which sorted grain can pass by mechanical means or gravity to a gathering and/or bagging location (not shown).

In one example grains of wheat were projected by gravity as described towards a row of containers and it was found that the grains collecting on containers 4,5, and 6 as marked in the drawings had the required properties for milling for bread making flour.

The machine illustrated in Figures 2 to 4 operates in two stages. The first is a double inclined rotary screen used to remove trash and cracked grain. The second passes a precisely metered amount of grain through a discharge device two metres wide in which every grain, regardless of shape, size or weight, is shot out with exactly the same speed and angle above the horizontal into a parabolic trajectory. Each grain is free to determine its own trajectory; the denser grains of higher specific weight assume a trajectory with a long horizontal range, the less dense grains a shorter one. The latter contains the grain with the low Hagberg number.

The machine comprises a hopper 21 containing an inclined rotary screen or drum 22 of perforated steel which is revolved in the hopper 21 by chain drives 23 via sprockets 24,25,26, from an electric motor 28 mounted in an accessible place on a sub-frame 29 outside the enclosed frame 31 of the machine. The frame 31 is stiffened and plated as necessary to support the necessary fixing shafts and bearings and is in the form of a casing which encloses most of the components of the machine.

Under the screen 22 a levelling auger 32 is located centrally in the hopper 21 for levelling the grain upstream of a feed roller 33 to ensure a regular and steady flow of grain to the feed roller 33. The amount of grain passing to the feed roller 33 is regulated by a gate 34. The gate is moveable across the grain path between the auger 32 and the roller 33 by adjustment of a handle 35. The roller 33 comprises a set of four longitudinal vanes 36 mounted on a shaft 37 and rotation of the shaft causes the vanes 36 to sweep the grain over a lip 38 into a chute 39 in a regular stream. The lip 38 is formed from angle material welded on the frame 31 at 250 to the horizontal. The frame is also strengthened by a box section 41 which forms a rigid bottom to the hopper 21.

In a further embodiment (not illustrated) the auger 32 and feed roller 33 are dispensed with. Instead the grain enters a wide downward chute to a distribution roller (not shown) which allows it to pass evenly into an intermediate chamber through which it falls to the variable speed impeller 51 described hereafter.

A sheet of wire mesh 42 on the side of the hopper 21 arranged between the hopper 21 and the chute 39 enables an operator to view the feed roller 33 in safety.

The system of sprockets and drives for the rotating elements from the motor 28 are as follows: The motor 28 drives pulley 17a via a "v" belt 43. A smaller pulley 17b coaxial with 17a transmits the drive via a single or twin belt 44 to auger 32 and pulley 16a using a moveable tension roller 45. The pulley 26a is coaxial and fixed with a sprocket 26b which drives the cleaning screen 22 via chains 23 and sprockets 24,25. Also mounted coaxially with pulley26a and fixed to rotate therewith is a gear wheel 46 which with gear wheel 47 and chain 48 provides a variable speed drive to the feed roller 33.

The chute 39 is a rectangular-section U-shaped passage open at the top with the centre line angled at approximately 450 to the horizontal. At the apex and mounted eccentrically in an impeller chamber 49 is a grain impeller 51, the construction of which is indicated in Figure 4. The four impeller blades 52 are made of a flexible and resilient material such as rubber, neoprene (RTM) or reinforced plastic (PVC) and are bolted to the square shaft 53 at a trailing tangent supported by respective plates 54.

Rotation of the shaft 53 from an impeller motor 55 and belt 56 causes the blades 52 to sweep the bottom of the chute 39. As the blade returns to its natural position it assists in shooting the grain pp the inclined outlet part of the chute 39. The outlet part of the chute includes an adjustable wall 57 for altering the choke of the chute 39.

The motor 55a for the impeller is positioned on slide rails (not shown) on a sub-frame (not shown). Adjustment of the position of the motor on the rails can be used to alter the speed of rotation of the impeller 51 in conjunction with an automatic variable speed drive pulley 55b. Angle pieces 58 help constrain the shape of the impeller chamber 49 and the chute 39 and impeller chamber 49 are fixed to the frame 31 via brackets 59 . The impeller acts purely mechanically to impel the grain and not as a fan. The outlet arm of the chute 39 opens into a separation chamber 61 into and through which a stream of air is drawn from an intake 62 by a centrifugal extractor and blower fan 63 for aspirated cleaning.The air stream forms a counter flow which pneumatically modifies the grain trajectories by slowing tne grain down.The air intake may be regulated by a butterfly valve 64 located in the intake conduit 62. There are three outlets from the separation chamber, a first outlet 65 for selected grain or head corn, a second outlet 66 for rejected grain or tailings and a third outlet 67 via the fan 63 through which dust and chaff is drawn on the air stream. The first and second outlets each include respective grain collection chambers 68,69 having an open end out of which the grain is delivered by respective augers 71,72 driven by respective belts 81,82 from a pulley 17b on the same shaft as the pulley 17a. If required conduits can be fitted to the outlets to convey the grain to a different location.

A slideably mounted grain pan 73 is angled approximately 450 to the horizontal and includes at the upper end a divider 74. The grain pan 73 forms a catching site for lower density grain. The grain pan is attached to the inner of telescopically mounted threaded members 75 which extends and recedes in response to the turning of a handle 76.

Rotation of the handle 76 moves simultaneously the divider 74 and the grain pan 73.

Underneath the grain pan is a conduit 77 leading directly down to the first chamber or collecting bin 68 access to which is above the divider 74. At the lower end the grain pan 73 extends partially across a door 78 to which it.is parallel and which is hinged at the lower end, the door forming a roof to the first chamber 68 as well as functioning as an extension to the grain pan when closed.

The second chamber or collecting bin 69 is disposed adjacent the first chamber 68 and at the bottom of the grain pan 73 and grain pan door 78. Underneath the grain collecting chambers 68,69, but not connected to them, is a conduit 83 leading directly from the separation chamber 61 via a chaff and dust collecting chamber 84.

To pre-clean the grain the divider 74 is moved to its uppermost position which may reduce or totally close off the gap between the divider 74 and the roof 79 of the separation chamber 61. The door 78 is opened to the position shown in dashed lines in which it closes the access to the second chamber 69. The grain passes over the inclined rotary drum 22, unwanted material or trash passing through the perforations in the steel sheet and out of the machine through the end of the drum. At the bottom of the hopper 21 the grain is levelled by the auger 32 and fed into the chute 39 by the roller 33. The impeller 51 protects the grain into the separation chamber 61 whereupon it collects on the grain pan 73 and slides down through the open door 78 into the first chamber 68.The air from the air intake cannot pass above the divider and so travels down the conduit 77 and up through the open door 78 against the direction of motion of the grain to clean the grain of dust and chaff which dust etc is carried through a dust and chaff collecting chamber 84 adjacent the second chamber, passing under the chambers 68 and 69 through the duct 83 and the fan 63 to an outlet 67. The dust and chaff is exhausted to a cyclone or dust hopper away from the working area.

In an alternative arrangement for pre-cleaning, the grain pan 73 is raised to the uppermost position and the door 78 is left closed. This leaves a small gap between the grain pan 73 and the door 78. The air intake is then directed through the conduit 77 and speeds up as it passes through the gap into the chamber 61. The chaff is collected as above and the cleaned grain falls into the second chamber 69.

To use the machine as a gravity separator the grain pan door is first closed and then the handle 76 is turned to move the divider and grain pan downwardly by a predetermined amount. The position of the divider will have been determined in advance depending on what grain is to be collected and can subsequently be adjusted according to the output sample required. With the first and second chamber 68,69 open and the conduit to the first chamber opening to the separation chamber grain is fed to the hopper 21. The rotating screen 22 operates as before removing any trash.

Grain is levelled by the auger 32 and moved by the feed roller 33 down the chute to the impeller. Grain shot into the separation chamber travels along a trajectory dependent on its own individual properties landing either above or below the divider 74. That grain reaching above the divider falls into the conduit 77 and travels to the first chamber 68 to be conveyed out of the machine by the auger 71. That grain not reaching the divider lands into the second chamber to be conveyed from the machine by the auger 72.

For this operation the air flow through the intake is drawn into the separation chamber above the divider against the grain movement thus removing the dust and chaff on its stream via the dust and chaff collecting chamber 84.

Enclosing the machine and operating under a partial vacuum has the added advantage of rendering the environment of the machine substantially dust free thus easing the common problem of "farmer s lung" that is often encountered.

The machine provides a full range of adjustment for the process of gravity separation by using only a simple screw handle adjuster 76, throughput being adjustable by feed shaft speed changes and the position of the feed hopper slide 24 which can also be safely adjusted with the machine in motion.

The machine can be installed in situ in a grain handling area or fitted to a trailer chassis or to the chassis of a goods vehicle for use at different locations.

All the belts are "v" belts mounted outside bearings so that they can be replaced without dismantling the machine.

Chains are encased inside the frame to protect the belts and pulleys from oil.

The machine will process a variety of crops with a wide range of trash and moisture content enabling it to be used as both a pre-cleaner of grain going into store and a cleaner-separator for grain being moved out of store for sale.

Claims

1. A method of grading and/or sorting grain or seed comprising the steps of projecting grains or seeds at the same angle and the same speed in a stream; catching the grain/seed at first and second catching sites which are disposed in the path of the faring grain/seed, the second catching site being nearer to the projector than the first catching site; and collecting grain/seed that has fallen at the first catching site separately from the grain/seed that has fallen at the second catching site.

2 A method according to claim 1 including creating a counterflow of gas against the said stream and collecting particles picked up by the counterflow separately from the grain/seed.

3. A method according to claim 1 or 2 carried out in an enclosed environment.

4. A method according to any of the preceding claims including the step of pre-cleaning the grain/ seed by projecting it towards the catching sites against a counter flow of gas to remove unwanted particles before projecting the grain/seed a second time to grade/sort the grain/seed.

5. A method according to any of the preceding claims including pneumatically moderating the path of the grain/seed between the projector and the catching site.

6. Apparatus for grading and/or sorting grain/seed comprising a projector for projecting grains or seeds at the same speed and the same angle in a stream; first and second catching sites disposed in the path of falling grain/seed, the second catching site being nearer to the projector than the first catching site; and collecting chambers for collecting the grain/seed that has fallen at the first catching site separately from the grain/seed that has fallen at the second catching site.

7. Apparatus according to claim 6 wherein the projector and catching sites are disposed in an enclosure.

8. Apparatus according to claim 7 including a gas intake to the enclosure; the shape of the enclosure and the position of the intake being adapted to create a countergas flow to the stream of grain/seed.

9. Apparatus according to claim 8 including means for adjusting the speed of the gas flow.

10. Apparatus according to any of claims 6 to 10 wherein the first and second catching sites are separated by a divider, the distance of the divider from the projector being adjustable to adjust the quality of grain/seed that falls at each catching site.

11. Apparatus according to any of claims 6 to 10 wherein the catching sites are disposed at an angle substantially equal to the projection angle of the grain/seed.

12. Apparatus according to claim 11 wherein the first catching site is above the divider and transfers grain directly to a first collecting chamber.

13. Apparatus according to claim 11 wherein the second catching site includes a collecting tray disposed below the divider for transferring grain/seed to a second collecting chamber.

14. Apparatus according to claim 13 wherein the second collecting site has access to the first chamber through a closeable door and the second collecting chamber is closeable enabling all the grain/seed to be collected in the first chamber during pre-cleaning.

15 Apparatus according to claim 14 wherein the door is moveable between a first position closing the said access and a second position closing access from the second collecting site to the second chamber.

16. Apparatus according to claim 13 wherein the divider and collecting tray are moveable away from the second collecting chamber leaving a gap between the collecting tray and the second chamber, the apparatus including means for directing a flow of gas through the gap against the falling grain/seed, the arrangement being such that the grain/seed is collected on the collecting tray, precleaned by the said gas flow and passed to the second chamber.

17. Apparatus according to any of claims 6 to 16 wherein the projector includes means for applying a mechanical propulsion to the grain/seed.

18 Apparatus according to claim 17 wherein the means for applying mechanical propulsion is a variable speed impeller housed in a chamber, the impeller including flexible blades which bend against the chamber wall during the propulsion part of the blade rotation.

19. Apparatus according to claim 7 wherein the contour of the enclosure roof is substantially parallel to the trajectory of the furthest travelling grain/seed.

20. Apparatus for-grading and/or sorting grain or seed substantially as herein described with reference to the acco mpanying drawings.

Amendments to the claims have been filed as follows

21 Apparatus according to claim 18 for sorting wheat grains to collect only those suitable for bread making as measured by the Hagberg test.

22.Apparatus according to 18 or 21 including a chute located to collect the output from the impeller, the chute having an adjustable wall for altering the amount coke of the chute

23. Apparatus according to any of claims 18,21,22 wherein the radius of the curved apex of the U-shaped chute which forms the lower part of the impeller chamber has a radius greater than the radius of the impeller and its blades.

24. Apparatus according to claim 23-wherein the vertical centre line of the impeller axis is disposed on the input side of the vertical line through the centre of the curved apex of the U-shaped chute.

25. Apparatus according to claim 24 wherein a line drawn between the centre of the impeller and the centre of the U-shaped chute makes an angle of 20 degrees with the vertical.