Abstract:
An apparatus for fracturing a crust on an agricultural field includes a tool bar and a support attached to the tool bar. A plurality of discs are non-rotatably attached to an axle that is rotatably supported by the support. Each of the plurality of discs include a plurality of spaced apart teeth about the perimeter of each disc. The teeth comprise convex surfaces and concave surfaces that converge at distal ends where the plurality of discs rotate about the support such that the convex surfaces penetrate and fracture the crust and that any debris or trash picked up by the teeth is ejected by the angles of the teeth and angles of the support brackets preventing plugging and destruction of the rowed crop.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a farm implement. More particularly, the present invention relates to a farm implement that fractures a crust on soil. 
     A typical method of preparing a field for planting crops includes using a moldboard plow or a chisel plow to work the ground after a harvest to bury crop residue and other debris in the soil. The following spring a seed bed is prepared in the field by tilling the soil and thereby loosening the soil, breaking up clumps of dirt and also leveling the surface. After the seed bed is prepared the crops are planted, typically in rows. 
     Another method of planting crops includes a “no-till” method. Using a no-till method includes leaving the soil unworked from the previous season with the crop residue or debris remaining on the surface of the field. Prior to planting the crop, the soil is tilled, typically with a tandem disc implement to cut the debris and prepare the seed bed. The crops are planted into the soil through the debris where the debris aids in preventing erosion. 
     A hazardous time for the seedlings occurs when a rain falls on the seed bed and creates a crust. If the crust is sufficiently thick, the seedlings may not be able to penetrate the crust and may subsequently die in the ground. If the seedlings is able to penetrate the crust, fine soil particles on top of the crust may be blown by the wind which may also harm the seedlings. 
     Typical farm implements that have been used to fracture the crust on a recently planted field include a rotary hoe. A rotary hoe includes a number of discs that have teeth around the perimeter. The teeth have at least one concave surface and another surface that typically form a point at a distal end. As the discs rotate the point and the concave surface penetrate, fracture and lift the crust such that if the seedlings find the penetrated, fractured and lifted crust, they are able to emerge to the surface. The rotary hoe also creates an uneven surface such that the fine particles are not blown into the seedlings. 
     However as the teeth rotate out of the soil, the concave surface has a tendency of carrying debris such as stocks or other crop residue, sticks, wire and/or rocks out of the soil and into an entanglement with other discs. The entanglement of the debris with the discs causes the discs to stop rotating and cease effectively breaking the crust. To remove the entanglement, the farmer must stop the tractor used to tow the rotary how, and manually remove the entanglement. Having to stop the tractor causes the farmer to use more time than necessary to work the field and thereby causes inefficencies. 
     SUMMARY OF THE INVENTION 
     The present invention includes an apparatus that is used to fracture a crust on an agricultural field. The apparatus includes a support that attaches to a tool bar. The support rotatably supports an axle having a plurality of discs non-rotatably attached to the axle. Each disc includes a plurality of spaced apart teeth about a perimeter of each disc. The teeth comprise convex surfaces and concave surfaces that converge at distal ends. The plurality of discs rotate about the support in a direction such that the distal end and the convex surfaces engage the crust. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a crust fracturing implement of the present invention being towed by a prime mover. 
         FIG. 2  is a side view of a unit of the crust fracturing implement of the present invention attached to a tool bar of a pull-behind row cultivator. 
         FIG. 3  is a top view of the unit of the crust fracturing implement of the present invention attached to the tool bar of the pull behind row cultivator. 
         FIG. 4  is a side view of an outside arm having an angled surface for ejecting trash and debris from the discs of the crust fracturing unit of the present invention. 
         FIG. 5  is a side view of a disc of a crust fracturing unit. 
     
    
    
     DETAILED DESCRIPTION 
     A crust fracturing implement of the present invention is generally illustrated in  FIG. 1  at  10 . The crust fracturing implement  10  is towed by a tractor  12  or any other prime mover and fractures the crust on a field while significantly reducing if not eliminating debris from becoming entangled within discs  20  of a crust fracturing unit  18 . The crust fracturing implement  10  includes a plurality of crust fracturing units  18  that typically correspond to the number of rows of a planter that was used to plant the field. 
     The crust fracturing implement  10  typically is a pull behind row cultivator  14  that is modified into the crust fracturing implement  10  of the present invention by removing the spring shanks (not shown) that support shovels (not shown) from each gang  15 . While modifying a pull behind row cultivator  14  is typical, the crust fracturing implement  10  of the present invention may be manufactured as a separate implement or by modifying other pieces of equipment. 
     The shovels (not shown) are typically utilized to uproot and kill weeds that sprout up between the rows of the crops. However, the shovels tend to break up the crust into larger chunks which may uproot the young seedlings or cover the row of seedlings with additional soil which may also kill the young seedlings. Further having the shovels tilling the soil would inhibit the ground speed at which the crust fracturing implement  10  operates effectively, typically in the range of between about 5 miles per hour and about 8 miles per hour. 
     Referring to  FIGS. 2 and 3 , each crust fracturing unit  18  is typically mounted to a tool bar  16  where the tool bar  16  is mounted to a main frame  13  of the cultivator  14 . The tool bar  16  is typically secured substantially along a length of the cultivator  14  and typically supports cutting discs (not shown) that penetrate the soil proximate the rows and move the soil away from the rows and thereby uprooting weeds without harming the rows of crops. With the cutting discs removed from the tool bar  16 , a substantially vertical shank  22  of a support  23  is secured within a bore in a mounting bracket  24  that previously supported the cutting discs (not shown). A typical shank  22  is a solid member having a rectangular cross-section approximately ¾″ by 3″ that is positioned within the bore in the mounting bracket  24 . The shank  22  is secured in a selected position with a set screw  26  that threadably engages a threaded bore in the mounting bracket  24  to frictionally secure the shank  22  in the selected position. While a ¾″ by 3″ rectangular shank  22  is typical, any configured shank that mounts to any mounting bracket is within the scope of the present invention. 
     The support  23  includes left and right substantially horizontal members  33 ,  35  that are pivotally secured to the shank  22  with a bolt  31  positioned through aligned apertures in each of the left and right supports  33 ,  35  and an aperture located proximate a distal end of the shank  22 . Left and right inside arms  27 , 28  are welded to distal ends of the members  33 ,  35 , respectively. The arms  27 ,  28  have a similar configuration including an arcuate portion  32  proximate a distal end  34 . 
     Left and right outside arms  26 , 29  are aligned with the left and right inside arms  27 , 28  and are secured in selected positions with a plate  31 . The plate  31  is fixedly attached proximate the seam created by the left and right supports  33 ,  35  and the left and right inside arms  27 ,  28 , respectively. Proximal ends of the left and right outside arms  26 , 29  are fixedly attached to the plate  31 . 
     Referring to  FIG. 4 , the left and right outside arms  26 , 29  are similarly constructed and have the same arcuate configuration as the left and right inside arms  27 , 28 . The outside arms  26 ,  29  include apertures  33  that accept bearings (not shown). The left and right arms  27 , 28  also include apertures that align with the apertures  33  in the left and right outside arms  26 ,  29 . 
     Each arm  26 ,  27 ,  28 ,  29  includes a back portion that extends toward the perimeter of the discs  20 . An arcuate surface  37  of the back portion  35  engages debris that is carried by the discs  20  and discharges the debris from the crust fracturing unit  18 . As the discs  20  rotate, the angle created between the arcuate surface  37  and teeth  42  spaced around the disc  20  is typically between about 80° and about 130°. The relatively large angle between the arcuate surface  37  and the teeth  42  causes any debris to be discharged from the unit  18  such that the discs  20  freely rotate therein, unlike a typical rotary hoe which creates a relatively small angle between the teeth of the disc and the support which tends to bind the discs of a typical rotary hoe. 
     Referring to  FIG. 5 , the discs  20  are positioned between the arms  26 , 27 , 28 , 29  in an alternating fashion and are retained between the arms  26 , 27 , 28 , 29  with an axle  38  positioned through the bearings (not shown). Preferably the axle  38  has a substantially hexagonal cross-sectioned mid portion  39  that engages a substantially hexagon-shaped aperture  40  substantially centrally located on each disc  20 . The engagement of the flat surfaces on the axle  38  with the flat surfaces of the aperture  40  prevent the disc from rotating about the axle  38 . While a hexagon shaped aperture  40  and axle  38  are typical, any mechanism that prevents the discs  20  from rotating on the axle  38  is within the scope of the present invention including any polygonal configuration, at least one non-arcuate surface on the shaft  38  and the aperture  40  and a weld. 
     The axle  38  is retained within the bearing (not shown) with a threaded engagement of nuts with threaded ends  37  of the axle  38  as best illustrated in  FIGS. 2 and 3 . However, other retaining mechanisms are within the scope of the present invention including a cotter pin, a roller pin, a spring loaded pin within a collar, and a bolt with a locking nut and washers. 
     Typically each unit  18  includes five discs  20  that are separated by the four arms  26 , 27 , 28 , 29 . However it is within the scope of the present invention for a unit to include two or more discs and at least one arm. 
     Each disc  20  typically has sixteen substantially evenly spaced teeth  42  positioned about a perimeter of the disc  20 . While a disc with sixteen substantially evenly spaced teeth  42  is typical a disc with more or less than sixteen teeth are within the scope of the present invention. A disc  20  with teeth having a non-uniform length are also within the scope of the present invention. 
     Each tooth includes a convex surface  44  and a concave surface  46  that converge at a distal end  48 . Preferably the distal end  48  includes a flat or angular surface  50  that penetrates the crust substantially in a chiseling manner as the disc  20  is rotated. A typical angle of the surface includes an angle of about 15°. However a pointed distal end  48  or other configured distal ends are within the scope of the present invention. 
     The discs  20  are typically positioned on the shaft  38  such that only one tooth  42  penetrates the crust at one time. Staggering the position of the teeth relative to each other aids in penetrating and fracturing the crust. While only one tooth typically penetrates the crust at a time, it should be understood that more than one tooth  42  will be in the soil at any time. 
     The discs  20  and the axle  38  rotate in the direction of arrow  52 , as illustrated in  FIG. 2 , such that the angular surface  50  and the convex surface  44  fracture the crust. Fracturing the crust with the convex surface  44  forces any crop debris or residue, rocks, sticks or other obstacle into the ground such that as the tooth exits the ground the debris tends to remain in the ground thereby leaving the discs to freely rotate. The combination of the angular surface  50  and the convex surface  44  engaging and penetrating the crust along with the positioning of the arms  26 , 27 , 28 , 29  between the discs  20  prevents debris from becoming entangled with the discs  20  such that a field can be fractured without unnecessary interruption. 
     Because the convex surfaces  44  of the teeth  42  engage the crust, each unit  18  must provide a sufficient amount of force for the teeth  42  to penetrate the crust. A typical unit  18  with five discs  20  and four arms  26 , 27 , 28 , 29  weighs about fifty pounds which in most instances will provide enough force for the angular surface  50  and the convex surface  44  to penetrate the crust. 
     If additional force is necessary, a coil spring  60  is positioned about the bolt  31  on each end where a proximal end  62  of the coil spring engages the shank  22  and a distal end  64  engages the plate. The coil spring  60  applies a downward force typically in the range of five to ten pounds on the discs  20  and aids the teeth  42  in penetrating the crust. However, a coil spring is not necessary to practice the present invention. 
     The coil spring  60  also provides the additional benefit of retaining the teeth  42  in the ground when the unit  18  contacts an obstacle. Without the coil spring  60 , the unit  18  would have a tendency of raising when encountering a larger rock or clump of soil which would result in the teeth  42  disengaging the crust. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.