GB2132116A - Crop grader - Google Patents

Abstract

In a grader for the sizing of vegetable or fruit crops, a series of primary rollers 1 are connected by links 3 of a chain so as to be driven in a closed loop path. Secondary rollers 16 are suspended on the primary rollers 1 by means of pivot links 15 and these secondary rollers are supported at adjustable levels by means of secondary support rails 21 which are adjustably mounted on stanchions 8. The gap between a roller 16 and the non- associated adjacent primary roller 1 can thus be adjusted in accordance with the spacing of the roller 16 from the line of the roller 1. In order to prevent lodgement of crop between a roller 16 and its associated primary roller 1, a filling piece 31, which may also act as a cleaning device by means of distal edges 32, is provided. The rollers 1 and 16 are shown as being driven at the same peripheral speed by frictional contact with friction surfaces 6 and 22 on their respective support rails 7 and 21. <IMAGE>

Description

SPECIFICATION Improved crop grader This invention relates to crop graders, particularly for root crops such as potatoes, onions, carrots and for fruits such as apples, tomatoes and cucumbers.

The grading of crops includes sizing, in which the crop is sorted into sizes in accordance with predetermined requirements, and also a visual inspection for rejection of damaged or sub-standard items and also of foreign matter such as clods, stones or other inclusions.

The sizing is conventionally achieved in any of a number of ways of which the most usual are the use of a shaking square mesh, a continuous screen grader, a spool grader or a roller grader.

In the shaking square mesh method, the crop is introduced on to a wire mesh (in some cases rubber or plastics-covered to reduce damage) whose size is such that the crop below a certain size will fall through the mesh and above that size will pass over it. The mesh is vibrated in such a way that it causes the crop to move about freely and rotate to some extent in order to find its smallest section and also to advance the crop over the screen at the same time.

This system is particularly useful for spherical or near-spherical objects. In some cases the different mesh sizes are placed one above the other and in some cases one following the other.

A continuous screen grader operates in the same manner as the shaking square mesh, in that the crop passes through square holes in a mesh, but the mesh is in the form of a flexible chain or conveyor which is mechanically driven forward and shakes up and down at the same time. It is particularly suitable for near spherical objects and has the advantage of being self-cleaning because it returns upside down from the discharge point back to the beginning.

In a spool grader, a series of stationary shafts rotate with spools of such a shape that there exists between them a gap of the dimension of the size to be removed. The crop is rotated because it rests upon rotating spools and is moved over the machine either by declining the machine from shaft to shaft or because subsequent crop pushes it forward. This system is particularly suitable for spherical objects but is subject to a build up of mud on the spools. It is also damaging to early potatoes and onions which tend to get skinned by the rubbing action caused by the relatively high speed of rotation and the contact with surrounding crop.

In a roller grader, the crop is rotated and advanced on rollers which are set at such a distance apart that the crop passes through between the rollers. In one particular form, the rollers are mounted so as to be spaced apart by a distance which varies as the rollers progress. However, the mechanical arrangement for achieving this is complex and expensive. They also require considerable routine maintenance. In addition, the mud which is a prevalent part of agriculture, particularly in the United Kingdom, may cause inaccurate grading.

Ail the above sizing systems suffer from the disadvantage that changing the required size is relatively complicated and expensive. In principle, one unit of sizer will only take out one size and there is, therefore, a transfer from one unit to the next which usually involves either a drop which is damaging, or a transfer where the crop will remain stationary and rotate until pushed on by following crop, which tends to skin some crops.

Inspection is commonly carried out on advancing rotating rollers which rotate the crop so that all aspects can be seen by the inspector. It suffers from the disadvantage that the roller will tend to build up with mud in difficult conditions.

Also, the point at which the grading is done on the sizing machine is normally predetermined. It is usually either at a single inspection point between initial feed of the crop and the sizer, e.g. on a first elevated section of the machine, or on discharge conveyors for each size of acceptable crop. The latter arrangement is preferable but it does require a separate team of graders for each selected size of crop and-such substantial numbers of personnel are not always available or economic. However, since the machine is relatively inflexible in layout, the user is virtually committed to a particular requirement when purchasing the machine and this may turn out to be an expensive disadvantage.

In accordance with the present invention there is provided a machine for sizing crops comprising a series of primary rollers connected together and adapted to be driven along a closed loop path by means of chains or a like drive mechanism, means for driving the primary rollers in rotation about their own axes as they move along at least a sizing part of the said closed loop path, each of the said primary rollers having associated therewith a secondary roller arranged for pivotal movement relative to the primary roller whereby it varies the spacing between the secondary roller and an adjacent primary roller, and a series of supporting rails for engaging the secondary rollers to maintain the latter at a predetermined level in relation to the adjacent part of the said closed loop path, the said supporting rails being individually adjustable to adjust the level of the secondary rollers and hence the spacing between the secondary rollers and adjacent primary rollers along the respective lengths of the closed loop path.

Preferably the said rails are adapted to engage and drive the secondary rollers in rotation about their own axes as they move along with the primary rollers.

The said rails may be provided, as part of the path, with undulations, e.g. of toothed form, to agitate the crop to remove soil prior to sizing.

Each assembly of a primary roller and a secondary roller may include a filling piece to prevent the trapping of crop between the secondary roller and the associated primary roller. The filling pieces may be of Z form to provide scraping edges to clean the rollers.

The invention will be further described with reference to the accompanying drawings, in which: Figure 1 is a cutaway view illustrating the principal of the invention; Figure 2 is an elevation showing one position of use; Figure 3 is a section showing another position of use, and; Figure 4 is a diagram illustrating one particular form of complete grader.

Turning first to Figures 1,2, and 3, the crop grading machine includes a series of primary rollers 1 which have end assemblies 2 at each end thereof, which end assemblies 2 are rotatable with the rollers 1 and carry pins 4 which connect the links 3 of a continuous chain extending around the machine in a closed loop path as illustrated in Figure 4, the rollers 1 are thus constrained to follow this closed loop path as the chains formed by the links 3 and pins 4 are driven, e.g. by means of a chain drive wheel illustrated at 5 in Figure 4.

Over the crop sizing part of the closed loop path, the rollers 1 are in frictional or other driving engagement with a friction surface 6 of a support rail 7 which is supported at intervals from stanchions 8 by means of bearers 9 secured at fixed positions to the stanchions 8. By the use of such a friction surface 6 in engagement with a portion of the end assembly, the rollers 1 are driven at a predetermined peripheral speed. Where it is desired, in certain parts of the path, for the rollers not to be driven, the rails 7 are omitted and instead the chain is supported by means of rollers 11, forming part of the chain, which ride on supporting angles 12 running between the stanchions 8.

Figure 3 also illustrates a chain guard 13.

It will be seen that the rollers 1,which are in fact primary rollers, are widely spaced. In a typical example, the rollers will have a diameter of 51 mm and will be at a pitch of 153mm, leaving a space between the rollers of 102 mm. These figures are of course only given by way of example and other diameter, spacings and relationships between the roller diameter and spacing may also be adopted.

Each primary roller has as part of its end formation a reduced diameter portion 14 which acts as a bearing for a link 15 at each end of the roller. The links 15 support secondary rollers 16 which are freely pivotable by reduced diameter bearing portions 16(a). The rollers 16 in the example illustrated are of the same diameter as the primary rollers 1 and may be deemed secondary rollers. It will be seen in Figure 1 that the secondary rollers 16 illustrated are of the same diameter as the primary rollers 1 and normally trail their associated primary rollers 1. The rollers 16 are adapted to be supported at different levels in relation to the position of the path of the rollers 1 so that the size of the gap between the roller 16 and the following primary roller 1 will vary.At the left-hand side of Figure 1, the roller 16 is shown as at the same level as the rollers 1 and the gap 17 will thus be, in the example given 26mm. Thus, any crop item below this size should fall through the gap on this part of the run. Further along, the gap will have increased in size, as shown at 17a, as the roller 16 is taken to a lower position and will for instance be 40mm. Still further to the right, the roller 16 will be still further down, and the gap shown 17b will for instance be 60mm. To the extreme right of the Figure, the primary roller is shown as hanging freely in a vertical position, so that the sizing gap is then that between two adjacent rollers 1, namely 102mm in the example given.

The position of the secondary rollers 16, other than in the freely hanging position shown in the extreme right of Figure 1, will be determined by the position of a secondary supporting rail 21, which again has a friction surface 22 in engagement with the surface of the secondary roller. In Figure 2, the secondary supporting rail 21 is shown supported by a bearer 23 at the same level as the supporting rail 7 for the primary rollers 1, while in Figure 3 the secondary supporting rail 21 is shown in a lower position. It will be appreciated that if the secondary supporting rail 21 is parallel with the primary supporting rail, the gap between the secondary roller 16 and its following primary roller 1 will be constant, but if the secondary support rail 21 is inclined, as shown at the right-hand side of Figure 1, then the gap will vary progressively as the rollers advance.One possible procedure would be for the secondary supporting rail 21 to be downwardly inclined as illustrated so that the gap increases progressively.

It will be seen that the rollers 1 and 16 on the sizing part of the run will rotate at the same peripheral speed so that tendency to scuff and peel the crop supported between them will be minimised.

The support of the secondary supporting rollers 21 is by means of the bearers 23 attached to the stanchions, and it will be seen in Figure 1 thatthe stanchions 8 are provided with slots 24 to enable the position of the rails to be readily adjusted, and suitable fastening means are provided to enable the adjusted position to be maintained.

The spacing between a secondary roller 16 and its associated primary roller 1 is fixed by the length of the links 15, and in the example illustrated is equivalent to the minimum gap 17. Accordingly it is necessary to prevent crop from being trapped between a secondary roller 16 and its associated primary roller 1, and this is achieved by locating a filling piece 31 between the rollers.

The filling piece 31 is shown as of Z form and it thus has two distal edges 32a and 32b which act as scraping edges to cooperate with the peripheries of the rollers 1 and 16 to prevent the build of mud on those rollers, in addition to preventing crop settling between the associated primary rollers. When the secondary roller 16 is below the associated primary roller 1, the filling piece 31 will gravitate to the secondary roller and the free edge 32a will bear on and scrape the secondary roller. At some point on the return run ofthe machine the primary roller 16 would be lifted by a rail so as to cause the filling pieces 31 to gravitate to the primary roller so that the other free edge 32b would thus bear on and scrape the roller.

The upper surface 33 of the Z shape filling piece 31 is almost flush with the upper surfaces of the rollers, so there is very little tendency for the crop to settle on this surface, and one or more flexible curtains 34, e.g. of rubber, may be provided to sweep the crop back into the following gap 17. Obviously, as the secondary rollers move into the downwardly deflected positions, the sloping of the upper surfaces 31 tends to dislodge any crop from that surface.

It will be seen that if a number of separate independent, adjustable secondary supporting rails 21 are provided, the sizing part of the machine may be readily adapted for wide range of sizing requirements by selective positioning of the rails 21 by adjustment of the bearers 23 in the slots 24.

Turning now to Figure 4, there is shown a complete grading machine having ground wheels 41 and a tow-bar 42 to enable it to be moved to suitable locations, and there is also provided a support jack 43 or group of such jacks, to enable the machine to be free standing.

The chains associated with the rollers 1 passes over the afore-mentioned drive sprockets 5 and guide sprockets 44 and further guide sprockets 45.

The bottom or return run of each chain is supported on a frame member 46 of the machine, and the chain is shown as hanging freely between the sprockets 5 and the frame member 46.

During this return run, the rollers may be cleaned by dipping or spraying if required. Also, the rollers may have chemical dressing applied for various agricultural and crop storage conditions, e.g. sprout suppressant or fungicide.

Between the sprockets 44 and 45, the rollers 1 and 16 form an elevator for crop fed onto this inclined portion, and for this purpose the rollers are not rotating over this particular inclined run. Some small material and foreign bodies will in fact fall between the rollers over this part of the run, and will drop onto a conveyor 47 feeding a spoil or reject cross conveyor 48. The lower part of the inclined run has an impermeable surface below it. A drive belt 49 for the conveyor 47 is shown as being driven by the shaft of the sprockets 44.

Following the sprockets 45, the secondary support rails for the rollers 16 have a section which is undulating e.g. of toothed form as shown by the reference 51, and the purpose of this is to agitate the crop at this point to settle it into the gaps 17 and to cause small items of crop and foreign bodies to drop through onto the conveyor 47. In the example illustrated, the chain rises gently between the sprocket 45 and the sprocket 5 while the support rail for the rollers 16 is shown as being generally horizontal, so that the gap between the secondary rollers and the following primary rollers is of a steadily increasing nature.

Following the undulating section 51 it is envisaged that inspection booths may be provided to enable visual inspection to take place and rejected crop to be dropped down shoots onto the conveyor 47.

Under sized crop will also fall through onto the conveyor 47. As an alternative, the cross conveyors 52, 53 and 54 illustrated in dotted lines may be provided to remove small sizes.

And a further alternative, is that a combination of inspection and cross conveyors may be provided at this range so that, for example, small materials automatically reject onto the cross conveyor 52 and then there is a constant gap zone for inspection prior to the main sizing.

Following the position of the cross conveyor 54, there is a main sizing phase in which a selected size of crop is dropped onto the cross conveyor 55 while a larger size passes on beyond the end of the rail 21 so that the secondary rollers 16 then drop to fully open position and an even larger size of crop falls onto the cross conveyor 56. Oversized crop is carried on over the sprocket 5 and drops off the end of the machine.

It will be envisaged that by suitable positioning of the various links of the secondary support rail 21, the machine may be used for a wide variety of operations and inspection requirements dependent on the crop and local requirements, and the arrangement illustrated in Figure 4 is not to be regarded as limitative. It will be seen however that the machine can provide an elevator, a soil extractor, facilities for removing under sized crop, inspection facilities for the main grade and an intermediate sizing stage and an over size stage.

In the conventional grader, this sequence of operations would involve five transfers from one conveyor to another and each of these would involve potential damage to the crop. It will be seen that, it would in accordance with the present invention, the crop remains on a single conveyor line and is not transferred from one to the other. Also by the use of only a single conveyor line the drive requirements are greatly simplified with further considerable cost savings. It will be seen therefore that this machine has the advantages of giving less damage to the crop, and the possibilities of improved grading accuracy by the ready adjustability of the sizing parameters. There is also a flexible layout so that the machine may be readily adapted to requirements which may vary from crop to crop.The adjustment of the size required can be achieved without changing any of the elements or parts so there is a saving of time and cost and there is also a considerable mechanical simplicity. It is also to be noted that the rollers are substantially self-cleaning, having regard to the use of the filling pieces 31 which also act as cleaners for the rollers.

Various modifications may be made within the scope of the invention. In particular, it is to be noted while the secondary rollers 16 are shown in Figure 1 as in a trailing relationship to the primary rollers, they could be in leading relationship. Also, the driving parts of the rollers 1 could for instance be outside the chain by locating the drive part of the roller on an extension of the link 4 beyond the chain and having the support rail 7 apppropriately located.

The method of adjustment of the support rails could be achieved in any of a number of ways, and in particular the use of screw adjustments, cams, levers or motorised adjustments is envisaged. Further, the surfaces 6 and 22 of the support rails are shown as being roughened friction surfaces for engaging the appropriate parts of the rollers 1 and 16 respectively, but in certain circumstances it may be preferred to use a rack and pinion type of drive to obtain a more positive drive which might be less liable to wear.

Also it is to be noted that while the Z shape of the filling piece 31 is preferred, other shapes, such as an H shape could be used to arrive at the same facility of cleaning and support.

Claims (12)

1. A machine for sizing crops comprising a series of primary rollers connected together and adapted to be driven along a closed loop path by means of chains or a like drive mechanism, means for driving the primary rollers in rotation about their own axes as they move along at least a sizing part of the said closed loop path, each of the said primary rollers having associated therewith a secondary roller arranged for pivotal movement relative to the primary roller whereby it varies the spacing between the secondary roller and an adjacent primary roller, and a series of supporting rails for engaging the secondary rollers to maintain the latter at a predetermined level in relation to the adjacent part of the said closed loop path, the said supporting rails being individually adjustable to adjust the level of the secondary rollers and hence the spacing between the secondary rollers and adjacent primary rollers along the respective lengths of the closed loop path.

2. A machine as claimed in claim 1, wherein the supporting rails are adapted to engage and drive the secondary rollers in rotation about their own axes as they move along with the primary rollers.

3. A machine as claimed in claim 2, wherein over a length of the path of the rail is provided with undulations to agitate the crop to remove soil and other small inclusions prior to sizing.

4. A machine as claimed in claim 3, in which the undulations are of a toothed configuration to provide sharp changes of direction.

5. A machine as claimed in any of claims 1 to 4, in which the secondary rollers are supported on the primary rollers by means of pivot links.

6. A machine as claimed in any of claims 1 to 5, in which each assembly of a primary and a secondary roller also includes a filling piece to prevent the trapping of crop between the secondary roller and the associated primary roller.

7. A machine as claimed in claim 6, in which the filling pieces are provided with scraping edges to clean the rollers.

8. A machine as claimed in claim 7, in which the filling pieces are of Z form.

9. A machine as claimed in any of the preceding claims, in which the secondary rollers each trail the associated primary roller.

10. A machine as claimed in any of the preceding claims, in which the primary rollers are driven by engagement with stationary rails along a selected part of the closed loop path.

11. A machine as claimed in any of the preceding claims, in which the said closed loop path comprises an elevation and feed section over which the rollers are not driven in rotation about their own axes.

12. A machine for sizing crops substantially as hereinbefore described with reference to the accompanying drawings.