Abstract:
A row unit comprises a row unit gearbox with two shearing edges and two stalk rolls with corresponding shearing edges, wherein the stalk roll shearing edges shear against the gearbox shearing edges when the stalk rolls rotate during normal operation of the row unit, thereby chopping material that might otherwise be wrapped around the row unit gearbox and be jammed between the stalk rolls and the gearbox.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to row units for corn heads of agricultural combines. 
       BACKGROUND OF THE INVENTION 
       [0002]    In one common configuration, known in the prior art, corn heads comprise a laterally extending frame to which many row units are attached. The frame is configured to be supported on the front of an agricultural combine. Each row unit is configured to engage an individual row of crop plants, cutting the crop plant from the ground, and stripping the crop from the corn stalk. In one common row unit configuration, the row unit grasps the cornstalk, pulls it downward, and pulls the ears of corn off the stalk. These ears of corn are then provided to the threshing, separating, and cleaning portions of the agricultural combine to remove the individual kernels of corn. These kernels of corn are saved in a grain tank in the harvester. 
         [0003]    Row units for corn heads typically have two forwardly extending rolls called “stalk rolls” that are disposed adjacent to each other. The stalk rolls are driven in rotation such that corn stalks trapped between them are pulled downward and ejected into the dirt below the corn head while the ears of corn are stripped off the stalk. 
         [0004]    One problem with the row units for corn heads is their susceptibility to being jammed with shreds of plant matter, corn kernels, dirt, grass, or other materials on the ground. The row units skid along the ground, permitting all manner of contaminants to be introduced into the row unit. 
         [0005]    A typical stalk roll may rotate at 1000 rpm as it travels along the ground only a few inches away from the dirt. Grass, weeds, broken corn stalks or other material may become jammed between the spinning stalk roll and the row unit gearbox on which it is mounted. 
         [0006]    One solution to this problem has been to locate the stalk roll very closely to the gearbox itself providing a very small gap therebetween. Nonetheless, long fibrous plant material can become wrapped around the base of the stalk roll and wedged into this gap. 
         [0007]    What is needed, therefore, is a row unit with an improved row unit gear box and stalk roll that reduced the likelihood of contamination. It is an object of this invention to provide such a row unit and stalk rolls. 
       SUMMARY OF THE INVENTION 
       [0008]    In accordance with a first aspect of the invention a row unit for a corn head is provided, the row unit comprising a gearbox having two adjacent and forwardly extending stationary tubes; and first and second stalk rolls having a plurality of longitudinal knives, the stalk rolls being mounted for rotation on and concentric with the stationary tubes; wherein a portion of the gearbox adjacent to the first stalk roll has a first shearing edge and a portion of the gearbox adjacent to the second stalk roll has a second shearing edge, and further wherein the first shearing edge is disposed to shear a mating shearing edge on the first stalk roll and the second shearing edge is disposed to shear against a mating shearing edge on the second stalk roll. 
         [0009]    In accordance with a second aspect of the invention, a stalk roll for a row unit of a corn head is provided, the row unit comprising a row unit gearbox having two forwardly extending stationary tubes disposed adjacent to each other with counter rotating helical protrusions disposed on the outer surface of the stationary tubes the row unit further comprising two stalk roll drive shafts, wherein a stalk roll drive shaft extends from each of the stationary tubes and is concentric therewith, the row unit gearbox further comprising a shearing edge disposed adjacent to the base of each stationary tube, the stalk roll comprising a stalk roll tube having a hollow interior configured to receive the stationary tube; and a plurality of longitudinally extending knives disposed on and extending generally radially outward from the stalk roll tube; wherein each of the plurality of longitudinally extending knives defines a stalk roll shearing edge along the leading surface of the knives that is configured to engage the shearing edge disposed adjacent to the base of the stationary tube on which the stalk roll is configured to be mounted, such that contaminating matter trapped between the stalk roll shearing edge and the gearbox shearing edge is sheared. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a bottom view of a row unit for a row crop harvester in accordance with this invention. 
           [0011]      FIG. 2  is a bottom view of the row unit of  FIG. 1  showing one stalk roll and the row unit gearbox on which it is mounted. The other stalk roll and the other components of the row unit have been removed for ease of illustration. 
           [0012]      FIG. 3  is a perspective end view of the stalk roll of  FIG. 2  showing the multiple knife arrangement, the flat end surface, and two clearance holes provided in the cylindrical body of the stalk roll. 
           [0013]      FIG. 4  is a front view of the row unit gearbox with both stalk rolls removed showing the shearing surface formed in a row unit gearbox adjacent to the base of the stalk rolls. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]      FIG. 1  is a bottom view of the corn had row unit  100  in accordance with the present invention. The row unit  100  includes a gearbox  102  to which two forwardly extending arms  104 ,  106  are bolted. The front end of each arm  104 ,  106  has a skid pad  108 ,  110  that is disposed to skid along the ground as the row unit and the harvester on which it is attached are propelled through the field. There is a gap  112  that extends between the two arms  104 ,  106  into which successive plants in the row of corn plants is drawn. On either side of this gap  112  are two stalk rolls  114 ,  116  that rotate about their longitudinal axes  118 ,  120  respectively. Corn plants entering into gap  112  between the two stalk rolls  114 ,  116  are grasped by the longitudinally extending knives  122  that extend from the surface of the stalk roll tube  123  that forms the body of each stalk roll. In the embodiment illustrated here, each stalk roll has eight of these longitudinal knives  122  spaced generally equidistantly about the circumference of the stalk roll tube  123 . The forward end of each stalk roll  114 ,  116  has a helical flute  124 ,  126  that engage the cornstalk just as it enters into the gap and ensure that is drawn rearward in the gap between the two stalk rolls. 
         [0015]      FIGS. 2-4  illustrate the row unit gearbox  102  with stalk roll  114  attached to the gearbox and with one stalk roll  116  removed for convenience of illustration. The forward portion of gearbox  102  includes a stationary tube  128  that extends forward into the open end of the stalk roll  116 . In  FIG. 2 , the right stalk roll  116  has been removed to show the stationary tube  128  on which stalk roll  116  is mounted, and the rotating drive shaft  130  that is coupled to stalk roll  116  to drive it in rotation about its longitudinal axis  120 . 
         [0016]    The outer surface of stationary tube  128  has a helical protrusion  132  disposed on the cylindrical outer surface of stationary tube  128  that extends substantially the entire length of the stationary tube  128 . The helical protrusion is twisted such that material trapped between the stalk roll  116  and stationary tube  128  is pushed to the rear (i.e. toward the gearbox  102 ). An identical stationary tube drive shaft, and helical protrusion is disposed within stalk roll  114 . The helical protrusion on the stationary tube within stalk roll  114 , however, has an opposite direction of twist since it rotates in the opposite direction as stalk roll  116 . It also pulls contaminants toward the rear of stalk roll  114 . 
         [0017]    Both of the stalk rolls  114 ,  116  have two through holes  134  disposed on diametrically opposite sides of the stalk roll tube  123  adjacent to the end  136  of their respective helical protrusions. By locating holes  134  at the end  136  of the helical protrusions, material that is forced backwards by the relative rotation of the stalk rolls with respect to their helical protrusions is pushed to holes  134 , where the centrifugal force generated by the rotating stalk roll causes the material to be ejected. This insures that the forward portion of the stalk roll is kept clear of contaminated material. 
         [0018]    Gearbox  102  includes at least one shearing edge  138  that extends forward toward the right end (in  FIG. 2 ) of the stalk roll  114  and extends generally radially outward from the axis of rotation  118  of stalk roll  114 . Shearing edge  138  is positioned very closely to the rear end of the stalk roll such that material caught between the stalk roll  114  and the shearing edge  138  is sheared off and thereby prevented from wrapping around the end of the stalk roll and becoming jammed between the stalk roll and the base of the stationary tube. An identical mirror image shearing edge  140  is similarly located at the base of stalk roll  116  to similarly shear material that is caught between stalk roll  116  and shearing edge  140 . 
         [0019]    Referring now to  FIGS. 3 and 4 , we can see that each of the eight longitudinal knives  122  of stalk roll  114  has a generally radially extending leading edge  142 . Stalk roll  116  similarly has eight knives with leading edges arranged in mirror fashion which function exactly the same. It is this leading edge  142  that engages a generally radially extending shearing edge  138  (shown in  FIG. 3  as a dashed line) to shear material in the gap between the two edges. Every time stalk roll  114  completes a single revolution, there are eight successive shearing strokes for each of the eight forward edges  142  to shear against shearing edge  138  of gearbox  102 . Shearing edge  140  shears identically against the forward leading edges of stalk roll  116 , but in mirror fashion. Stalk rolls  114 ,  116  typically rotate at 1000 rpm. Thus, there are 8000 shearing strokes per minute (average) when the row unit is being driven through the field. At this speed, material that begins to be wrapped around the end of stalk roll  114  is usually sheared before it can wrap completely around and become jammed into the gap defined between the end of stalk roll  114  and the stationary tube that is disposed inside stalk roll  114 . Stalk roll  116  is identically arranged as the end of stalk roll  114 , but in a mirror arrangement to provide the same shearing strokes between the leading edges of its eight longitudinal knives  122  and shearing edge  141  gearbox  102 . 
         [0020]    On occasion, some plant matter or dirt will manage, even though it is sheared, to enter the space between the end of stalk rolls  114 ,  116  and the stationary tubes on which the stalk rolls are mounted. When this happens, the material tends to migrate forward in an axial direction toward the forward tip of the stall rolls as the stalk rolls rotate. Holes  134  in the stalk rolls  114 ,  116  permit this material to be expelled as it migrates forward and prevents it from accumulating inside the stalk rolls. 
         [0021]    These two separate mechanisms, (1) the holes formed in the stalk rolls that interact with the helical protrusions to clear the forward ends of the stalk rolls, and (2) the shearing action provided by the interaction of the generally radially extending edges  142  on the end of the stalk rolls that interact with the generally radially extending shearing edges  138 ,  140  both serve to keep the stalk roll and gearbox and the gap in between cleaned out and clear.