BACKGROUND

Modern conventional agricultural combine harvesters or “combines” utilize removable and interchangeable attachments called “headers” or “heads” which are adapted for harvesting different types of crops. An example of a conventional combine10is shown inFIGS. 1 and 2with a conventional header attachment20used for harvesting corn (i.e., a “cornhead” or “cornheader”). The conventional cornheader20includes a plurality of conical crop divider points22(“points” or “snouts”) which extend forwardly and diverge rearwardly. Row unit assemblies30are disposed between the adjacent points where the rearwardly diverging points22nearly converge. InFIG. 1, a cornhead20is illustrated with twelve row unit assemblies30(i.e., a 12-row cornhead) but it should be understood that cornhead sizes typically range from four rows to twenty-four rows or more.

As illustrated inFIG. 3, during harvesting operations, the combine10is positioned with the points22of the cornhead20positioned between adjacent corn rows12and below the ears14on the cornstalks16. It should be appreciated that as the combine10drives forwardly through the field as indicated by the arrow18inFIG. 2, the conical, rearwardly diverging shape of the points22causes the cornstalks16within each row12to be guided and directed into the row unit assemblies30between the adjacent points22. As explained in more detail below, the row unit assemblies30separate the ears14from the cornstalks16and convey the separated ears toward the cross-auger24. The cross-auger24augers the separated ears14toward the opening27of the feederhouse26in the middle of the cornheader20. The feederhouse26conveys the ears14into the interior of the combine where the corn kernels are separated from the corncob. The separated kernels then pass over a series of screens which separates unwanted crop material and other residue from the kernels. The clean grain is then carried by elevators to a clean grain holding tank while the corncobs, leaves, husks and cornstalks which entered the combine are chopped and discharged through the rear of the combine and mix with the cornstalks that pass under the combine.

Referring toFIGS. 4-6, each row unit20includes a pair gathering chains32,34with outwardly extending lugs36. The gathering chains32,34extend around drive sprockets38and idler sprockets39(FIG. 5). Rotation of the drive sprockets38causes the gathering chains32,34to rotate in adjacent parallel paths such that as the combine10drives forwardly through the field, the outwardly extending lugs36draw the cornstalks16into the row unit30. Below the rotating gathering chains is a pair of spaced stripper plates40,42. The stripper plates40,42are spaced sufficiently apart to define a gap44between them which is sufficiently wide to permit the corn stalks16to enter but which is sufficiently narrow so that the corn ears14cannot pass through. A pair of rapidly rotating stalk rolls50,52are positioned below stripper plates40,42.

As best illustrated inFIG. 6, during harvesting operations, the rotating stalk rolls50,52rapidly pull the corn stalks16downwardly through the gap44between the stripper plates40,42such that when the corn ears14engage the stripper plates40,42, the ears14are pulled or stripped from the cornstalks16. Ideally, as the stalk rolls50,52rotate, the entire cornstalk16is pulled downwardly through the gap44and is returned to the field below the header20as the combine drives forwardly (FIG. 2). It should be appreciated that if the cornstalk snaps or breaks prior to ear separation or after ear separation such that the entire cornstalk is not pulled through the gap44, the amount of plant material entering the feederhouse26will increase, requiring more horsepower and thus more fuel consumption. The stripped ears14which remain on the stripper plates40,42after the cornstalk16is pulled through the gap44are then conveyed by the lugs36of the gathering chains32,34upwardly and rearwardly to the cross-auger24. The cross-auger24augers the ears14to the feederhouse26, and the feederhouse26feeds the ears14into the interior of the combine for shelling and separating the kernels from the corncob as is known in the art.

While conventional stalk rolls generally serve their intended purpose to pull and strip the ears from the cornstalks, conventional stalks rolls do not achieve the necessary throughput of crop material when harvesting at higher speeds. Conventional stalk rolls typically have a tapered nose portion and a cylindrical body portion. The nose portion is typically fitted with auger flights while the cylindrical portion has a plurality of horizontal flutes that run parallel to the axis of the stalk roll with the flute profile co-radial with the cylindrical portion. In use, as illustrated inFIG. 6, as the stalk rolls rotate, the auger flights on the nose draw the cornstalks towards the cylindrical body. Once the cornstalk is between the cylindrical bodies of the adjacent stalk rolls the horizontal flutes crush the cornstalks and pull the cornstalks downwardly through the stripper plates40,42as previously described. It has been found that the transition point between the auger flights on the nose and the horizontal flutes on the cylindrical body of the stalk roll often restricts the throughput of the cornstalks, such that the cornstalks seam to hesitate or fail to advance, or even bind, at this transition point despite the rotation of the auger flights and forward advancement of the combine. If the cornstalks stall at this transition point, the gathering chains may snap off or break off the cornstalk causing a large portion of the cornstalk to be pulled into the cornheader and fed into the combine rather than the stripped cornstalk passing under the cornheader as previously described. Additionally, if the cornstalk is snapped off prematurely or whipped around by the stalk rolls, the corn ears can be flung from the stalk and land on the ground and not be harvested.

Second, some stalk rolls do not effectively cut and crush the cornstalk, thereby leaving long sections of the cornstalk intact and not cut and crushed in more than one direction with respect to the axis of the cornstalk. These long sections decompose very slowly, limiting their potential benefit to subsequent crops. Still other stalk rolls chop and crush the cornstalks so finely, as to potentially create a negative impact on soil microbial activity which can negatively affect the next season's crop. For example, the cornstalks that are cut and crushed and pass under the cornheader, together with the unwanted corncobs, husks and leaves that passes through and are discharged by the combine, i.e., the crop residue—commonly called corn stover—has a carbon to nitrogen to ratio of 57:1. When the stover is chopped to small pieces, soil microbes will quickly work to decompose the stover. This relatively rapid decomposition forces the microbes to find additional nitrogen to go with the excess carbon to consume the stover because it contains a greater proportion of carbon to nitrogen. The soil microbes then tie up any excess nitrogen available in the soil, called immobilization, creating a deficit of nitrogen in the soil, which nitrogen deficit can extend into the next crop season thereby negatively affecting the critical early growth stages of the next season's crop. This condition may persist until the beneficial soil microbes die, decompose, and release nitrogen (mineralization) contained in their bodies, or some other source of nitrogen becomes available in the soil.

Third, some stalk rolls are not designed to crush and cut varying cornstalk diameters. For example, cornstalks have a larger diameter at their base near the root system and the diameter decreases along the length of the cornstalk toward the tassel. It is important that the entire cornstalk length be crushed and cut to the appropriate residue size to aid in decomposition.

Accordingly, there is a need for a stalk roll which allows for high throughput of plant material, which crushes the cornstalks in more than one direction and is capable of chopping cornstalks of varying diameters across the field and of varying diameters along the length of the cornstalks to aid decomposition in the field.

