Weed Seed Destruction with Improved Wear Characterisitics

Abstract

Weed seeds are destroyed in the chaff from a combine harvester by repeated high speed impacts caused by a rotor mounted in one of a pair of side by side housings which accelerate the discarded seeds into contact with stator bars at angularly spaced positions around the axis of the rotor. U-shaped bars are symmetrical and can be reversed when the second leg is worn for extended life. Parts of the rotor and stator which are radially outward of other parts are formed with a higher resistance to wear approximately proportional to the radius so that the wear characteristics of the different parts are matched to the velocity of the particles impacting the different portions to generate symmetrical wear throughout the structure

Claims

1. A weed seed destructor for mounting on a combine harvester having a separation system for separating harvested crop into a first material comprising straw and a second material comprising chaff and weed seeds, the weed seed destructor comprising: an inlet receiving the second material comprising chaff and weed seeds; a first plurality of surfaces and a second plurality of surfaces, both pluralities being mounted for engaging the second material comprising chaff and weed seeds; the first and second surfaces being mounted for relative rotation such that the second material comprising chaff and weed seeds is impacted between said first and second surfaces during said relative rotation, the relative rotation occurring around an axis of rotation; wherein at least one of the first and second plurality of surfaces have a characteristic such that a resistance to wear of at least one inner surface closer to the axis is less than a resistance to wear of at least one outer surface more distant from the axis.

2. The weed seed destructor according to claim 1 wherein the first plurality of surfaces comprises a rotor which rotates around the axis.

3. The weed seed destructor according to claim 2 wherein the rotor which rotates around the axis comprises a set of inner surfaces surrounding the axis and a set of outer surfaces spaced radially outwardly from the set of inner surfaces.

4. The weed seed destructor according to claim 3 wherein the set of outer surfaces spaced radially outwardly from the set of inner surfaces comprises an annular ring of outer surfaces.

5. The weed seed destructor according to claim 4 wherein the set of outer surfaces comprising the annular ring of outer surfaces each have said resistance to wear thereof which is greater than the resistance to wear of the set of inner surfaces.

6. The weed seed destructor according to claim 1 wherein the second plurality of surfaces comprises a stator.

7. The weed seed destructor according to claim 6 wherein the stator comprises a set of inner surfaces surrounding the axis and a set of outer surfaces spaced radially outwardly from the set of inner surfaces.

8. The weed seed destructor according to claim 7 wherein the set of outer surfaces spaced radially outwardly from the set of inner surfaces comprises an outer annular ring of outer surfaces and the set of inner surfaces comprises an inner annular ring of inner surfaces which inner ring is coaxial to the outer ring.

9. The weed seed destructor according to claim 8 wherein the set of outer surfaces comprising the annular ring of outer surfaces each have said resistance to wear thereof which is greater than the resistance to wear of the set of the inner annular ring.

10. The weed seed destructor according to claim 1 wherein surfaces of both of the first and second plurality of surfaces have a characteristic such that a resistance to wear of an inner surface closer to the axis is less than a resistance to wear of an outer surface more distant from the axis.

11. The weed seed destructor according to claim 1 wherein the first plurality of surfaces comprises an outer annular ring of outer surfaces and an inner annular ring of inner surfaces which inner ring is coaxial to the outer ring and wherein the second plurality of surfaces comprises an outer annular ring of outer surfaces and an inner annular ring of inner surfaces which inner ring is coaxial to the outer ring, wherein the annular rings of the first and second pluralities are arranged alternately in the radial direction of the axis.

12. The weed seed destructor according to claim 1 wherein the first plurality of surfaces comprises a plurality of blades extending radially outwardly from an inner end at or adjacent the axis to an outer end for rotation around the axis and wherein an inner part of each blade has a surface characteristic such that a resistance to wear of the inner end closer to the axis is less than a resistance to wear of the outer end more distant from the axis.

13. The weed seed destructor according to claim 1 wherein each inner surface and each outer surface is formed on a body, with a part only of the body, which part faces toward a flow of the second material so as to engage the second material, having said characteristic.

14. The weed seed destructor according to claim 1 wherein each inner surface and each outer surface is formed on a body, with a first part of the body, which part faces toward a flow of the second material so as to engage the second material, having said characteristic and a second part of the body, facing away a flow of the second material so as not to engage the second material, having said characteristic so that the body is reversible to place the second part facing toward the flow of the second material.

15. The weed seed destructor according to claim 14 wherein each body comprises a u-shaped bar.

16. The weed seed destructor according to claim 1 wherein said characteristic is provided by different characteristic of a hard surface coating material on the surfaces where the characteristic comprises hardness, thickness or composition of the hard surface coating material.

17. The weed seed destructor according to claim 1 wherein said characteristic is provided by a different characteristic of bodies defining the surfaces where the characteristic of the body comprises hardness, thickness, composition or dimension of the body.

18. The weed seed destructor according to claim 1 wherein said characteristic of said inner surface closer to the axis is arranged relative to said outer surface more distant from the axis such that in use a wear life of each of said inner and outer surfaces is similar.

19. The weed seed destructor according to claim 1 wherein the surfaces of common characteristic form part of a common body so that the characteristic can be applied commonly to all surfaces of the body.

20. A combine harvester comprising: a separation system for separating harvested crop into a first material comprising straw and a second material comprising chaff and weed seeds; and a weed seed destructor according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0087] One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:

[0088] FIG. 1 is an isometric view of a prior art apparatus shown in the above mentioned PCT publication WO 2020/069602 for destruction of weed seeds according to the present invention which is arranged in a first embodiment where the rotary mill section is mounted at a position on a combine harvester at the rear of the sieve so as to discharge the chaff and destroyed seeds towards the straw chopper's tailboard to enhance residue spreading to both sides of the combine harvester.

[0089] FIG. 2 is an isometric view of the apparatus for destruction of weed seeds of FIG. 1 which shows the structure of the rotary mill.

[0090] FIG. 3 is a cross sectional plan view of one rotary mill of FIG. 2.

[0091] FIG. 4 is an isometric view of the stator frame of FIG. 2.

[0092] FIG. 5A is a detailed view of a portion of FIG. 3 which shows rotor and stator components according to the present invention with increasing coating thickness as the components radial position from the rotor center increases.

[0093] FIG. 5B is a detailed view of a portion of FIG. 3 which shows rotor and stator components according to the present invention with increasing coating hardness or different composition as opposed to thickness as the components radial position from the rotor center increases.

[0094] FIG. 5C is a detailed view of a portion of FIG. 3 which shows rotor and stator components according to the present invention where the components themselves are of increasing thickness as the components radial position from the rotor center increases.

[0095] FIG. 5D is a detailed view of a portion of FIG. 3 which shows rotor and stator components where the components themselves are of increasing hardness or different composition as opposed to thickness as the components radial position from the rotor center increases.

[0096] FIG. 5E is a detailed view of a portion of FIG. 3 which shows rotor and stator components according to the present invention where the components themselves are of increasing transverse dimension as the components radial position from the rotor center increases.

[0097] FIG. 6 is a graph of Coating thickness vs Time to fail coating in relation to the arrangements above according to the present invention which shows a linear relationship.

[0098] FIG. 7 is a graph of Tip Velocity vs radial location in relation to the arrangements above according to the present invention.

[0099] FIG. 8 is a graph of Velocity vs Wear Rate in relation to the arrangements above according to the present invention.

[0100] FIG. 9 is a graph of Wear Rate vs Chemical Composition and Microstructure Modification in relation to the arrangements above according to the present invention.

[0101] FIG. 10 is a graph of Wear Rate vs Hardness in relation to the arrangements above according to the present invention.

[0102] In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION

[0103] The structure of the weed seed destructor is shown and described in detail in the above published PCT application WO 2020/069602 to which reference may be made for any details not included herein.

[0104] The apparatus herein is shown in FIG. 1 mounted on a combine harvester carried on ground wheels and including harvesting components of a conventional nature the rearmost one of which is the sieve which discharges chaff and discarded seeds including weed seeds to the rear edge of the sieve.

[0105] The combine harvester includes a chopper and discharge arrangement 9 shown in FIG. 1 is basically as shown in U.S. Pat. No. 6,840,854 issued Jan. 11, 2005 of Redekop, the disclosure of which is incorporated herein by reference. The chopper thus comprises a housing 10 defined by a top wall 11, a bottom wall 12 and two end walls 13. The end walls 13 include attachment means 13A for attachment of the housing to the outlet of a combine harvester for discharge of straw and optionally chaff from the combine harvester into an inlet opening 15 of the housing 10. The bottom wall 12 defines a semi-cylindrical portion extending from the inlet 15 to an outlet through which chopped straw and air is discharged at relatively high velocity for spreading across the field in a wide spread pattern.

[0106] Within the housing is mounted a hub 17 which is carried on suitable bearings mounting a shaft for rotation about a hub axis at a center of the housing so that blade members 19 carried by the hub sweep around within the housing to entrap straw fed through the inlet 15 and to carry the straw and air past stationary blades for chopping and for discharge through the outlet. The stationary blades 20 are mounted on the housing at a position approximately midway between the inlet 15 and the outlet so that the blade members 19 sweep between the stationary blades in a cutting action.

[0107] In this arrangement of the chopper, there is provided three axially spaced sections of the chopper assembly including a first fan section 30 at one end of the hub 17 and the second fan section at the other end of the hub 17. In-between the two narrow fan sections 30 is defined a center section 30A which provides the whole of the cutting action.

[0108] The chopper and spreading assembly 9 is arranged to be mounted at a rear straw discharge of the combine harvester and includes the housing 10, the rotor 17 mounted in the housing 10 for rotation around a generally horizontal axis and carrying the plurality of chopper blades 19 for chopping the discharge material.

[0109] At the exit is provided the material spreading assembly which can be the form of a tailboard 16A with guide fins 16B for receiving the chopped material and spreading the material to the rear and sides of the combine harvester.

[0110] In the Figures the seed destructor which includes two separate destructor elements 38, 39 side by side each including a housing 35 with base 37 and an outer surface 40 upstanding from the base and extending to an outlet or discharge mouth 41. The base and outer surface are covered by a top planar cover panel 42 which has an opening 43 Inside a center part of the spiral which defines a central inlet for feeding the material from the sieve containing the chaff and weed seeds onto a rotor 44 mounted on a hub 45. Around the hub 45 is provided a plurality of pivot pins or bolts 46 each carrying a pair of flail blades 47. The flail blades extend from an inner end connected to the pin 46. The flails can retract inwardly by pivotal movement in the event of impact with a larger object. Thus the blades are pivotally mounted about an axis parallel to the rotor axis so as to act as flails.

[0111] The rotor 44 includes the hub 45, the flail blades 47 and two outer rings 60 and 62 of bars 61, all of which rotate around the axis of the hub.

[0112] Around the rotor is provided a stator formed by three stationary annular coaxial cylinders 51, 52 and 53 with cylinder 51 inside the cylinder 52. The stator cylinders are carried on the top cover 42 so that they hang down from an upper annular flange fixed to the cover. The cover forces the weed seeds to contact the stator and rotor thus devitalizing the seed.

[0113] Each stator cylinder is of the construction shown in FIG. 3 and includes a top flange, a bottom ring parallel to the flange and a plurality of upstanding connecting posts or bars 57 to form a rigid structure.

[0114] The rings 60 and 62 of the rotor are coaxial with and located between the stator rings 51, 52 and 53.

[0115] In operation, the rotor flails 47 acts to suck chaff and weed seed into the mills and accelerate and direct the material across the inside surface of the inner annular stator ring 51 to impact, shear and force some of the material through the spaces between the bars 57.

[0116] The stator ring 53 has the same structure as the stator rings 51 and 52 but of increased diameter. The outer stator ring therefore operates in the same manner under the rotation impetus on the material from the posts of the rotor ring 62 to impact and shear the material and then to allow any remaining material remaining on the inner surface of the outer stator to escape outwardly. The material escaping is flung outwardly and angularly against the outer surface 40.

[0117] Each stator bar 57 comprises an elongate member which includes three impact surfaces which can be varied in size and length to vary the number of impacts a weed seed encounters as it passes through each stage of the mill. The stator bar is preferably U-shaped in cross-section with a base 576 and two legs 575 and 577 facing outwardly from the blades with the apexes 573 curved with a radius. Thus the stator bars also can be reversed when worn on the leading edge.

[0118] The arrangement herein thus provides a stator bar which includes a tangential surface, an apex at a leading edge of the tangential surface and a third surface which is generally radial whereas previous arrangements typically before have had either a tangential or radial or apex, but not all three and thus provides an advantage over, and differentiator from, the prior art, enabling higher weed seed devitalization rates at lower power requirements.

[0119] The stator bar is preferably formed by bending a strip of sheet metal along a center line or approximately at the center line to form the legs 575 and 576 with a smooth curve 573 interconnecting the legs. The apex 573 defines a radius of curvature which can lie in the range 5 to 15 mm and more preferably of the order of 7 mm. However the same surfaces can be formed on the outside of a body which is a solid bar, not a bent strip or on the outside of a hollow bar.

[0120] A seed is carried along in the direction by the rotation of the rotor blade so that it moves around the axis with some outward movement under centrifugal force. Some seeds impact the leg 575 on its inner surface. Some seeds pass through the opening between the trailing end of the leg 575 and the apex 573 of the next stator bar. These seeds and accompanying material will escape outwardly from this stator to the next stator or to the wall 40. Some of that material may engage the radial outwardly extending surface of the leg 575 so as to change direction but generally any material impacting the bar outside of the apex will escape outwardly. Some of the seeds and material will impact the bar 57 at the apex 573.

[0121] The second leg 577 typically lies in an axial plane of the axis of the rotor but in some cases where the bend in the strip forming the bar is greater than 90 degrees, the leg 572 may be close to or even alongside the leg 571. The legs are typically flat as the only bend in the strip is at the apex.

[0122] It will be noted that the rotor has three components defined by the blades 47, the rings 60 and 62 which are at different spacing from the axis so that the blades 47 are closest to the axis, the ring 60 is outward of the blades and the ring 62 is outward of the ring 60. Thus these components rotate at the same angular velocity but at different linear velocities related to the difference in radius,

[0123] It will be noted that the stator has three components defined by the ring 51, the ring 52 and the ring 53 which are again at different spacing from the axis so that the ring 51 is closest to the axis, the ring 52 is outward of the ring 51 and the ring 53 is outward of the ring 52. These components are stationary but it will be appreciated that the velocity of the weed seeds and other particles impacting these components and driven by the rotor varies in proportion to the radius from the axis X.

[0124] As shown in FIG. 5A, each of the bars 57 of each of the stator rings is coated on the front surface of the base 576 and on the outside faces of the legs 575 and 577 by a coating material which provides a resistance to wear. This material is shown at 505 on the bars in the ring 51 and the coating 505 extends from an edge 506 at the end of the leg 575 to an edge 507 at the end of the leg 577. The coating extends around the curve 573 and across the base 576 and covers the whole height of the bar.

[0125] The bars in the ring 52 have a coating 515 and again the coating 515 extends from an edge 506 at the end of the leg 575 to an edge 576 at the end of the leg 577. The coating extends around the curve 573 and across the base 576 and covers the whole height of the bar of the ring 52. Further the bars in the ring 53 have a symmetrical coating 535.

[0126] The rings 51, 52 and 53 are each formed separately from one another so that these can be separated and removed individually from the structure. Each ring is formed as an integral body including the top and bottom flanges and the interconnecting bars. Each integral ring can therefore be manufactured with the bars thereof having characteristics required to match the requirements of the ring concerned.

[0127] In particular, the surfaces of the bars which are exposed to contact with the second material are covered by the coating which is selected so that the first plurality of surfaces defined by the bars of the rings of the stator have a surface characteristic such that a resistance to wear of the inner surfaces of the bars of the ring 51 closer to the axis is less than a resistance to wear of the outer surface of the bars of the ring 52 more distant from the axis. Similarly the bars of the rings 52 and 53 of the stator have a surface characteristic such that a resistance to wear of the inner surfaces of the bars of the ring 52 closer to the axis is less than a resistance to wear of the outer surface of the bars of the ring 53 more distant from the axis.

[0128] Similarly the bars 601 and 602 of the rotor rings 60 and 62 are coated by a layer 603 and again the coating 603 extends from an edge 604 part way around the circular bar 601 from an outer tangent around the inwardly facing side of he bar 601 to an edge 605 again spaced from the outer tangent. The coating extends around the bar 601 to protect those areas that are impacted by the second material and covers the whole height of the bar 601 of the ring 60.

[0129] The rings 60 and 61 are each formed separately from one another so that these can be separated and removed individually from the structure. Each ring is formed as an integral body including the top and bottom flanges and the interconnecting bars. Each integral ring can therefore be manufactured with the bars thereof having characteristics required to match the requirements of the ring concerned.

[0130] Again the coating 603 is arranged to have lesser wear characteristics than the coating 613.

[0131] The difference in wear characteristics can be provided by modifying the coating or the layers by any one of many different techniques known to provide difference in wear characteristics. These can include:

[0132] -a- Where the different wear properties are provided as shown in FIG. 5A by different thicknesses of the hard surface coating material.

[0133] -b- where the different wear properties are provided as shown in FIG. 5B by different compositions of the hard surface coating material so that the thickness is the same but the material is different.

[0134] -c- where the different wear properties are provided as shown in FIG. 5B by different hardness of a hard surface coating material so that the thickness is the same but the material hardness is different.

[0135] -d- where the different wear properties are provided as shown in FIG. 5B by different microstructure modification of the surfaces so that the thickness is the same but the material is different.

[0136] The difference in wear characteristics can be provided by modifying the bars themselves which are free from a coating material by any one of many different techniques known to provide difference in wear characteristics. These can include:

[0137] -a- Where the different wear properties are provided as shown in FIG. 5C by different thicknesses of bars 57, 578 and 57 of the stator and bars 608 and 609 of the rotor.

[0138] -b- where the different wear properties are provided as shown in FIG. 5D by different compositions of the bars themselves so that the thickness is the same but the material is different. Thus the bars 57, 578 and 579 of the stator. have materials of increasing hardness, as do the bars 608 and 609 of the rotor

[0139] -c- where the different wear properties are provided as shown in FIG. 5D by different hardness of the bars themselves so that the thickness is the same but the material hardness is different.

[0140] -d- where the different wear properties are provided as shown in FIG. 5D by different microstructure modification of the bars themselves so that the thickness is the same but the material is different.

[0141] -e- where the different wear properties are provided as shown in FIG. 5D by different microstructure modification of the bars themselves so that the thickness is the same but the material is different.

[0142] -f- where the different wear properties are provided as shown in FIG. 5E where the components 57, 578 and 579 of the rotor are themselves of increasing transverse dimension as the components radial position from the rotor center increases. That is the radial dimension of each of the bars increases to provide additional material to increase the resistance to wear of the bars proportionally to the spacing from the axis. Similarly the bars 608 and 609 of the rotor are of increasing width.

[0143] FIG. 6 is a graph of Coating thickness vs Time to fail coating which shows a linear relationship.

[0144] FIG. 7 is a graph of Tip Velocity vs radial location

[0145] FIG. 8 is a graph of Velocity vs Wear Rate

[0146] FIG. 9 is a graph of Wear Rate vs Chemical Composition and Microstructure Modification.

[0147] FIG. 10 is a graph of Wear Rate vs Hardness.

[0148] These graphs show that the resistance to wear can be selected using any one of the above techniques and that the resistance to wear is a linear graph of the characteristics of the material allowing the wear characteristics to be selected proportionally to the radius and hence to the linear velocity of the particles as they impact the respective rings.

[0149] It will be appreciated that the rings forming the rotor or the rings forming the stator can be formed with the characteristics defined above or more preferably both are. However in some designs this may not be necessary depending on wear patterns.

[0150] As set forth above this concept can be used in many different designs of mill and the wear pattern can be determined and the location of the requirement for hard coating determined. The concept concerned is that the wear resistance characteristic is increased depending on the radius of the component from the axis and it will be appreciated that this can be applied to any of the above cited designs.

[0151] Also as shown in FIG. 2 the blade 47 includes the fan blade surface 50 which lies in a plane parallel to the axis X and has a height matching that of the bars so that the leading surface 503 of the fan blade 50 acts to accelerate the weeds and other particles so that they impact the bars of the stator ring 50.

[0152] The same concept can also be optionally applied to the surface 503 so that an inner portion 504 of the surface 503 is coated or formed with a wear resistance less than that of an outer portion 505 due to the fact that the portion 505 is further from the axis and hence moving at a higher linear velocity and thus receptive to a higher wear from these particles. It will be appreciated that the bars of the ring 51 are designed to return some of the particles inwardly so that there are repeated impacts on some particles between the blade portion 50 and the inner ring 51. This same concept can be used with any rotating blade of the mill where there is a significant difference in radius between one portion and another. The different characteristics can be obtained by any one of the above techniques.

[0153] Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.