Patent Application
20090120340
The present invention relates to agricultural implements and, more specifically, to knife and point structure for applying fertilizer below the ground surface.
Many growers in the United States are currently switching from conventional tillage methods or minimum tillage methods to zone or strip tillage methods to reduce input costs and increase crop yields. The strip tillage machines currently on the market are designed to perform zone tillage, apply fertilizer, and make a mellow, friable seedbed for the upcoming crop. Residue levels for strip tillage range from light soybean stubble to heavy standing corn stubble.
An implement for zone or strip tillage typically includes a cutting coulter, a row cleaner, and fertilizer injection knife system mounted on a shank assembly and covering disks. The cutting coulter is design to cut residue, and the row cleaner removes crop residue from the formed strip. The shank-mounted fertilizer injection knife system fractures the soil in the strip and applies fertilizer. The covering disks are designed to catch the dirt spray off of the fertilizer knife and move the dirt back over the row to seal the fertilized area and make a berm.
Many of the currently available strip tillage implements have problems with residue flow between the fertilizer knife and closing disks. The residue flow problems result from the operation of attaching brackets for a tall knife at ground level or in the ground when the strip-till bar works at depths from approximately six to ten inches. Residue catches on the brackets and impedes the flow of residue and soil clods between the knife and closing disks. Once there is sufficient residue build up, clearance between the knife and closing disks disappears. With no clearance, the closing disks stop turning and a ball of residue and clods starts to drag. The operator then has to stop the machine to dislodge the plug.
Providing an economical knife point that is long-wearing and has good soil operation characteristics has also been a continuing source of difficulty. Welded knife points have worked well but are expensive to manufacture and usually require replacement of the entire long knife when the point is worn out. Providing good subsurface soil shattering action without soil slabbing, excessive knife side wear, and excessive soil surface inversion and disturbance also continues to be a source of difficulty, especially on fertilizer knives working in strip tillage applications.
A knife assembly constructed in accordance with the teaching of the present invention includes a unique point defining several fracture areas and preventing slabbing and similar soil action that causes wear on the knife and excessive soil disturbance. The knife has an extended length between the point and upper mounting brackets to facilitate operation of the point over a substantial range of depths, and the mounting brackets operate well above ground level even at the deepest operation. The smooth knife shank sheds residue easily and eliminates the plugging typical in conventional knife assemblies with the bulkier mounting brackets having transversely extending bolts.
Referring to
The knife assembly 22 includes a spring trip shank assembly 30 connected at a forward end to the frame 12 extending rearwardly to a connection 32 with a long, upright knife 34. A replaceable point 40 is attached to the lower forward portion of the knife 34, and an NH3 tube 44 is attached to rear edge 46 to deliver fertilizer behind the point 40. The area of the connection 32 is offset a substantial distance above the lowermost portion of the point 40 so that the connection 32 is located above the surface of the ground when the point 40 is operating at maximum depth. By way of example for the strip tillage units 16 shown in
The knife 34 includes an upright shank portion 34a terminating at the area of the connection 32, which as shown in
The knife 34 terminates in a lower, forwardly projecting point receiving portion 34b. The point 40 is matingly received on the portion 34b and includes an upper apertured area 48 pinned to a corresponding apertured area on the knife 34 by a roll pin 50. The point 40 can be easily removed and replaced by driving the roll pin 50 from the apertures, sliding a new point 40 in place on the lower portion 34b and then driving a new roll pin 50 through the apertures.
At the juncture of the upright shank portion 34a and lower portion 34b, segmented shank protectors 54 are welded to front edge 56 of the knife 34. The shank protectors 54 extend upwardly from the top of the point 40 to cover the area of the exposed shank subject to the highest wear.
As best seen in
Opposed rearwardly diverging soil shattering surfaces 70 project upwardly from the lift surface 61 adjacent the leading edge 40a and extend rearwardly from a forward nose or edge 71 which terminates at a location 72 a substantial distance above the locations 61a. The soil penetrated at the forward area of the surface 61 is lifted to intersect the forward edge 71. The soil is forced outwardly by the diverging surfaces 70 which define a first soil shatter zone. The surfaces 70 terminate generally along a line extending between the locations 61a and 72, and upwardly and outwardly facing surfaces extend rearwardly from that line. The surfaces 76 converge at an upper rearwardly directed edge 78 which extends from the location 72 to the uppermost extremity of the point 40. Soil is forced upwardly and outwardly at the surfaces 76 where the collision of the soil flow from the surfaces 61 and 70 provides another soil shatter zone. At the rear of the surface 61 behind the location 61 a where the slope of the surface decreases, soil drops behind the surface 66 to define another shatter zone behind the point heel.
Generally parallel side surfaces 80 extend upwardly and rearwardly from the aft portion of the surface 61 along joint lines 82. The distance between the surfaces is less than the distance W1. Protrusions or fins 90 extend outwardly and downwardly from vertically offset locations on the surfaces 80. As best seen in
The multiple shatter zones provided by the unique surface configuration and fin structure described above shatters the soil to avoid slabbing effect for reduced draft and reduced wear on the sides of the knife. The point design with multiple shatter zones also reduces soil disturbance and soil inversion on the surface of the ground.
Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.
