Abstract:
A convenient user-friendly method to sharpen the rotary blade of a rotary cutter assembly without having to turn the rotary cutter assembly upside down. To this end, a rotary cutter assembly is provided with a special access door which is preferably securely fastened and/or locked during cutting and use of the rotary cutter assembly. When it is desired to sharpen the rotary blade, the door is unfastened and opened to permit access to the rotary blade. The rotary blade can then be clamped or otherwise secured and subsequently sharpened with a grinding wheel or other sharpening tool.

Description:
BACKGROUND OF THE INVENTION 
     This invention pertains to agricultural equipment and, more particularly, to a rotary cutter and method of sharpening a rotary cutter blade. 
     Rotary cutters, sometimes referred to as bush hogs, are powered and pulled by tractors and are very useful for mowing and cutting grass, weeds, fields of clover, and severing and chopping shrubs, bushes, and other plants, as well as twigs, branches, and plant debris on farmland. Rotary cutters are hitched to a tractor. Rotary cutters can also have a wheel so that the rotary cutter can be more smoothly pulled by the tractor. 
     Rotary cutter blades are quite large and typically span 4-10 feet. Rotary cutter blades rotate and spin in a manner somewhat similar to a propeller, except in a horizontal direction generally parallel to the ground (soil). Conventional rotary cutters have solid housings about the tops and sides of the rotary cutter blades and have open bottoms so that the rotary cutter blades can contact and cut grass, weeds, shrubs, bushes, etc. on the farmland. 
     The edges of rotary cutter blades are required to be sharp in the direction of rotation to cut grass, weeds, shrubs, bushes, etc. Conventional rotary cutters only permit manual access and contact of rotary cutter blades from the bottom of the rotary cutter. Conventional rotary cutters are also very heavy, bulky and awkward. 
     Sharpening, maintaining or replacing rotary cutter blades in conventional rotary cutters are very cumbersome, tedious and labor intensive. After conventional rotary cutters are stopped, unhitched and disconnected from tractors, 2-5 strong farmers are typically required to turn each rotary cutter upside down. The rotary cutter assemblies can be disassembled with various tools so that the rotary cutter blades can be removed and placed in vices for sharpening by grinders. 
     After conventional rotary cutter blades have been sharpened, the rotary cutter assemblies are re-assembled, tightened, and re-connected to the housings so that each rotary cutter can be lifted and turned right side up by 2-5 strong farmers. Such manpower is not always available when it is necessary to sharpen, maintain, or replace the rotary cutter blades. The rotary cutters are then hitched and reconnected to the tractors. The preceding method is not only awkward, clumsy, and tedious, but it can be dangerous, harmful and injure farmers, such as if the heavy housings crush the farmer&#39;s foot, or the blades cut the farmer&#39;s hands or feet. 
     It is important to keep the rotary cutter blades sharp to be able to efficiently cut grass, weeds, shrubs, bushes, etc. Dull blades can be totally ineffective in cutting grass, weeds, shrubs, bushes, etc. When rotary cutter blades start becoming dull, the tractor must often be driven over the same patch of land numerous times to cut all the grass, weeds, shrubs, bushes, etc., in the path of the tractor. This requires more fuel for tractors and is wasteful, time-consuming and costly to farmers. 
     It is, therefore, desirable to provide an improved rotary cutter and method of sharpening rotary cutter blades which overcome most, if not all, of the preceding problems. 
     SUMMARY OF THE INVENTION 
     An improved rotary cutter assembly and method is provided to easily sharpen the rotary blade of the rotary cutter assembly without having to turn the rotary cutter assembly upside down. Advantageously, the special rotary cutter assembly and method is convenient, easy-to-use, and effective. Desirably, user-friendly the rotary cutter assembly enhances operator safety, fuel economy, and efficient cutting. The economical rotary cutter assembly and method also uses less manpower, decreases labor costs, lowers downtime, reduces turnaround time, and improves maintenance and operation of the rotary cutter assembly. 
     The rotary cutter assembly can be used with a tractor or machine in areas where one or more rotary blades are useful to cut grass, weeds, fields of clover, shrubs, bushes, and other plants. The rotary blade can be rotated by a rotary-blade shaft (output shaft) via a coupling of a drive shaft or hydraulic pump or motor of the tractor or machine. Preferably, the rotary cutter assembly has a housing providing a frame to cover the rotary blade in order to protect the operator from cuttings and flying debris during operation of the rotary blade, as well as to protect the rotary blade from rain and the environment. A wheel assembly can be operatively connected to the frame to help elevate the cutter blade above the ground as well as to facilitate wheeled transport (pulling or pushing) by the tractor or machine. 
     In order to facilitate sharpening of the rotary blade, the frame has an opening to permit access to the rotary blade. The opening could be in the side (peripheral skirt) of the frame to permit sidewise (lateral) access to the rotary blade, but is preferably in the top (cover) to permit downward access from above to the rotary blade. The opening is closed by a special door, which is locked, bolted, or otherwise fastened and secured to the frame during operation of the rotary and cutter assembly in order to block the access opening and prevent cuttings and flying debris from striking the operator during rotation of the rotary blade. 
     When it is desired to sharpen the blade, the rotary blade can be stopped, the rotary-blade shaft (output shaft) can be disconnected (decoupled) from the drive shaft, the frame can be unhitched (disconnected) from the tractor or machine, and the door (hatch) can be unfastened (unlocked). The door can then opened, such as with a doorknob or other handle, to permit access through the opening to the rotary blade. The rotary blade can be secured, such as with a clamp and safety cable or strap, to help prevent rotation and other movement of the rotary blade during sharpening. A grinder (grinding wheel), file, or other sharpening tool (instrument) can then be used to sharpen the rotary blade. The preceding procedure can be reversed after the rotary cutter blade has been sharpened in order to use the sharpened rotary blades of the rotary cutter assembly to cut grass, weeds, shrubs, bushes, plants, etc. 
     A more detailed explanation of the invention is provided in the following description and appended claims, taken in conjunction with the accompanying drawings 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a rotary cutter assembly being pulled by a tractor in accordance with principles of the present invention; 
     FIG. 2 is a top view of the rotary cutter assembly; 
     FIG. 3 is a side view of the rotary cutter assembly with the access door opened and showing parts broken away from clarity and ease of understanding; 
     FIG. 4 is a side view of the rotary cutter assembly with the door closed; 
     FIG. 5 is a perspective top view showing the rotary blade being sharpened after the blade has been secured by a clamp and safety strap; and 
     FIG. 6 is a perspective view of a hinged door and lock. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A tractor  10  (FIG. 1) or other machine can be used to pull a rotary cutter assembly  12 , sometimes referred to as a“rotary cutter” or “bush hog”. The tractor can have front wheels  14  and larger back (rear) wheels  16 . The tractor can also have a tractor-hitch  18  to connect (couple) the tractor to the rotary cutter assembly  19  or other farm equipment. The tractor can be powered by a diesel engine or an internal combustion engine  20  and motor which drives and rotates a drive train  22  with a drive shaft  23 . 
     The rotary cutter assembly can be made of metal. The rotary cutter assembly can have a hitch assembly  24  (FIG. 1) which provides a rotary cutter-hitch. The hitch assembly can be coupled to the tractor-hitch to connect the rotary cutter assembly to the tractor. The rotary cutter-hitch assembly can comprise bars  25 - 31  which can include support bars and cross bars. The hitch assembly is welded, bolted or otherwise secured to a rotary cutter-housing  31  (housing) comprising a rotary-cutter frame  32 . 
     A rotary cutter-wheel assembly  34  (FIGS. 1,  3  and  4 ) can be pivotally connected via one or more pivot pins  35  to the rotary-cutter frame. The rotary cutter-wheel assembly can comprise rearwardly extending bars  36  and  37  which provides wheel-support arms, from which a caster  38  providing a wheel support assembly or hub, can be cantilevered and extend downwardly. The rotary cutter-wheel assembly can also have a rotary-cutter idler wheel  40  comprising a tire which can provide a rear swivel wheel. The wheel can be connected by an axle  42  or pins to the wheel-support assembly. The rotary cutter-wheel assembly and idler wheel are normally kept and disposed in a lower downward position as shown in FIG. 4 to facilitate wheeled transport, movement, and pulling of the rotary cutter assembly by the tractor. The rotary cutter-idler wheel (rear swivel wheel) can also help elevate the housing and rotary-cutter frame and one or more rotary cutter blades  44  (FIGS. 3 and 4) (rotor blades) off the ground. The rotary cutter-wheel assembly can be pivoted and raised to an upward position above the ground as shown in FIG. 3, prior to sharpening the rotary cutter blade. 
     The housing and rotary cutter-frame can have an open bottom  45  so that the rotary cutter blade can cut and mow grass, weeds, fields of clover, shrubs, bushes, and other plants, as well as bark, twigs, branches and plant debris on farmland. The rotary cutter blade can span 4 feet, 5 feet, 6 feet, 8 feet, 10 feet or more or less. The rotary cutter blade can be bolted, riveted, or otherwise secured to a flywheel pan assembly  46  (FIGS.  3  and  4 ). The flywheel pan assembly can be rotated by and connected to an output shaft  48  which can provide an upright rotary blade-shaft. The output shaft (rotary blade-shaft) can extend upwardly through the top  50  of the housing and rotary cutter-frame to a rotary cutter-coupling  52 . A pedestal  54  can be bolted or otherwise secured to the housing and rotary cutter-frame to elevate the rotary cutter-coupling above the housing and frame. The rotary cutter-coupling can connect the drive shaft of the tractor to the output shaft (rotary cutter-shaft) so that the tractor&#39;s drive shaft can drive and rotate the rotary cutter&#39;s output shaft in order to rotate and spin the rotary cutter blade. 
     The housing and rotary cutter-frame can provide a frame assembly which covers the rotary cutter blade. The housing and rotary cutter-frame can help prevent and protect the driver (operator) of the tractor and bystanders from being struck by cuttings (cut grass, cut plants, etc.) and flying debris during cutting, rotation and operation of the rotary cutter blade. The housing and rotary cutter-frame can further protect the rotary cutter blade from rain and the environment. The rotary cutter-frame can also support the coupling, hitch assembly, and wheel assembly. The top of the housing and rotary cutter-frame can provide an upper portion, deck, and protective cover which can be positioned above the rotary cutter blade. A peripheral annular skirt  56  (FIG. 2) can extend and depend downwardly from the top (cover) of the housing and rotary cutter-frame and can peripherally and annularly surround the rotary cutter blade. The skirt can provide a lateral shield which can help block and prevent grass, cuttings and flying debris from being spun and thrown laterally from the rotary cutter assembly during cutting, rotation and operation of the rotary cutter blade. 
     The top of the rotary cutter-frame can have a hole comprising a rotary cutter blade-access opening  58  (FIG. 5) to permit a person, such as the tractor driver, maintenance person, farmer, etc. to grasp, sharpen, and maintain the rotary cutter blade. Preferably, the access opening is of a size to allow the person to insert one or more hands, as well as a clamp  60  (FIG. 5) and a sharpening tool  62 , such as a power grinder (grinding wheel) to sharpen the rotary cutter blade. The illustrated access opening is rectangular, although in some circumstances it may be desirable that the access opening be circular or another shape. 
     A rotary cutter-door  64  (FIGS. 2-5) which can comprise a solid metal hatch, lid, closure, and barrier can be provided to cover, block, and close the rotary cutter blade-access opening when the rotary cutter assembly is operating and the cutter blade is rotating. The door can have an imperforate fluid impermeable, liquid impervious, central portion  66  (FIG. 5) which can cover the access opening, and can have a periphery  68  or peripheral flange which can peripherally surround the central portion. The periphery of the door can have door-holes  70  (FIG. 5) which provide bolt holes that can be aligned with frame-holes  72  (bolt holes) in the frame about the access opening to receive threaded studs or bolts  73 , nuts  74 , and washers  75  (FIG. 2) or other fasteners to bolt, lock, fasten, secure and tighten the door (hatch) in a closed position during operation of the rotary cutter assembly. If threaded studs are used, they can be welded to and extend upwardly from the top of the housing and frame. A safety chain  76  (FIGS. 1-4) can also be provided as a supplementary fastener to fasten and secure the door. The safety chain can be connected to the pedestal and an eyelet  77  (FIG. 4) extending outwardly from the door. The door can be slightly larger and of a similar shape as the access opening. The door can comprise a removable access door. In some circumstances it may be desirable to use a pivotable hinged door  78  (FIG. 6) with hinges  79  and pivot pins  80  or a slidable door secured by a lock, bar (rod) or other fastener(s). 
     The door can be provided with a manually grippable (graspable) portion that provides a handle  82  (FIG. 6) to grip the door. The handle can be U-shaped, although in some circumstances it may be desirable that the handle be in the form of a door knob or some other shape. The handle facilitates positioning the door in a closed position to cover the access opening during operation of the rotary cutter assembly when the cutter blade is rotating and spinning. The handle also facilitates grasping and opening the door to remove the door from the access opening, after the bolts or other fasteners have been unfastened and removed, in order to gain access to and sharpen the rotary cutter blade. The handle and door can also be secured and locked by an internal or external lock  84  such as a key actuated lock or combination lock. 
     When it is desired to sharpen the rotary cutter blade, the rotary cutter assembly and rotary cutter blade are deactivated and stopped. The drive shaft of the tractor can be disconnected and uncoupled from the rotary cutter-coupling and the output shaft (rotary blade-shaft) of the rotary cutter assembly. The tractor hitch can be unhitched, disconnected and uncoupled from the rotary cutter-hitch assembly. The rotary cutter wheel assembly and idler wheel can be pivoted and raised to an upward position as shown in FIG.  3 . The door can be unfastened and unlocked, by unfastening the safety chain and unfastening and removing the bolts, such as with a ratchet wrench, and/or by unlocking the lock. The door can then be opened, preferably by grasping the handle, to uncover and unblock the rotary blade-access opening to permit access to the rotary cutter blade. Preferably, the rotary cutter blade is secured in a stationary stopped position with a C-clamp  60  (FIG. 5) and an auxiliary safety strap  86  or safety cable to prevent movement of the cutter blade during sharpening of the blade. A sharpening tool  62 , such as a hand held power grinder  88  with a grinding wheel  90 , can be inserted and passed through the access opening to contact, grind and sharpen the rotary cutter blade. 
     After the rotary cutter blade is sharpened, the preceding procedure can be reversed as follows in order to use the rotary cutter assembly. Withdraw and remove the sharpening tool (e.g. grinding tool) from the rotary cutter blade and access opening. Unfasten and remove the safety strap and clamp. Close the door. Bolt, chain or otherwise fasten and lock the door. Lower the idler wheel to its normal downward position. Hitch the tractor hitch to the rotary cutter-hitch assembly. Couple the tractor drive shaft to the output shaft (rotary blade-shaft). Pull the rotary cutter assembly with the tractor. Rotate the rotary cutter blade via the tractor drive shaft to cut grass, weeds, shrubs, bushes, leaves, bark, twigs, branches and other plants and items desired to be cut. 
     Advantageously, the method of sharpening and maintaining the rotary cutter blade and rotary cutter assembly can be easily accomplished by one person without turning the rotary cutter assembly upside down, and without the need for 2-3 maintenance personnel as was previously done prior to this invention. 
     Among the many advantages of the novel rotary cutter assembly and sharpening method are: 
     1. Outstanding performance. 
     2. Superb cutting. 
     3. Excellent maintenance. 
     4. Enhanced safety. 
     5. Simple to use and implement. 
     6. Better fuel economy. 
     7. Longer blade life. 
     8. Less wear. 
     9. Fewer people required for maintenance. 
     10. Lower downtime. 
     11. Reduced turnaround time. 
     12. Decreased labor costs. 
     13. User friendly. 
     14. Convenient. 
     15. Economical. 
     16. Efficient. 
     17. Effective. 
     Although embodiments of the invention have been shown and described, it is to be understood that various modifications, alterations, and substitutions, as well as rearrangements of parts and process steps, can be made by those skilled in the art without departing from the novel spirit and scope of this invention.