Abstract:
The invention includes a cutting blade with replaceable cartridge having a main blade body with an at least one central axis, an at least one receiving section on the main blade body and penetrating through the main blade body. A replaceable cartridge has an at least one sharpened edge thereon and an at least one cartridge tab extending therefrom, the at least one cartridge tabs mating and penetrating and coupling with the at least one receiving section. And a locking mechanism is engaged when the replaceable cartridge is brought into proximity with the main blade body and the at least one receiving section is penetrated and coupled by the at least one cartridge tab.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the priority of U.S. provisional patent application 60/732,719, filed Nov. 3, 2005, which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates to a rotary cutting blade with replaceable cutting edge cartridge.  
         [0004]     2. Background of the Invention  
         [0005]     Cutting blade systems and rotary cutting blades in particular depend on maintaining an efficient cutting surface to operate effectively. This is especially the case in the professional lawn care industry, where rotary lawn mowers, rotary edgers, and similar devices are typically operated for long hours and over assorted terrain to manicure lawns. The blades of such lawn equipment are generally flat elongated piece of steel which are rotationally symmetric on a rotatable shaft. The blades have a sharpened edge on the leading edge of the outer portion of the blade. The outer portion trailing edge, particularly on lawnmowers, is generally slightly raised to cause a fan effect so as to lift the grass and to blow the clippings into a bag or direct the clippings in a desirous manner.  
         [0006]     The cutting edge of the blades typically become dull very quickly, from constant use and from contact with obstructions. While the equipment appears to be cutting for a long period of time, in actuality, the cutting edge may have ceased to be a true cutting edge and may thus sever blades of grass only because the mower blade is rotating very fast. Thus, the blades of grass are broken by the spinning blade and are bruised in the process. The grass develops a brown tip because of the bruising, has an unpleasing appearance, and is a damaged plant. Furthermore, since the dull blade must break the grass blades, instead of cutting them, the motor which rotates the blade is under an increased load, thus requiring more maintenance and consuming more fuel.  
         [0007]     In the past, the sharpening of these blades required the removal of the entire blade. Once the blade was removed, a new edge could be ground or filed onto the blade. The blade would then have to be remounted onto the shaft. This procedure is very difficult and very time consuming. Moreover, the ground or filed blades are often asymmetric and this asymmetry can cause additional torsional forces on the rotating shaft driving the blade, leading to even more costly repairs to the driving motor.  
         [0008]     Various types of replaceable cutters have been proposed to avoid the resharpening and eventual loss of the rotary blade. Such replaceable blades have presented problems of one type or another with regard to the requirement of complex fabrications, strength of the replaceable cutter, weakened resistant to damage by foreign objects, costs, and the like. There has remained a need for a blade with a strong cutter which can be easily replaced at a reasonable cost.  
       SUMMARY OF THE INVENTION  
       [0009]     An object of the invention is to provide a cost effective, simple solution to maintaining a sharpened blade edge in a cutting tool.  
         [0010]     An further object of the invention is to a secure and safe method of affixing a replaceable cartridge with a sharpened cutting edge on a main blade body, the cartridge being easily to remove and reinstall a new cartridge with a new sharpened edge after a period of use and wear on the original.  
         [0011]     The invention includes an apparatus and a method for using the apparatus.  
         [0012]     The invention includes a cutting blade with replaceable cartridge having a main blade body having an at least one central axis, an at least one receiving section on the main blade body and penetrating through the main blade body, a replaceable cartridge having an at least one sharpened edge thereon and having an at least one cartridge tab extending therefrom, the at least one cartridge tabs mating and penetrating and coupling the at least one receiving section, and a locking mechanism engaged when the replaceable cartridge is brought into proximity with the main blade body and the at least one receiving section is penetrated and coupled by the at least one cartridge tab.  
         [0013]     Moreover, the above objects and advantages of the invention are illustrative, and not exhaustive, of those which can be achieved by the invention. Thus, these and other objects and advantages of the invention will be apparent from the description herein, both as embodied herein and as modified in view of any variations which will be apparent to those skilled in the art. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     Embodiments of the invention are explained in greater detail by way of the drawings, where the same reference numerals refer to the same features.  
         [0015]      FIG. 1  shows an exploded view of an exemplary embodiment of the instant invention  
         [0016]      FIG. 2  shows a side view from the outside edge of the main blade body of the exemplary embodiment of  FIG. 1  with the replaceable cartridge attached.  
         [0017]      FIG. 3  shows a cross section of the exemplary embodiment of  FIG. 1  along line A-A with the replaceable cartridge attached. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]      FIG. 1  shows an exploded view of an exemplary embodiment of the instant invention. The instant invention is directed to a cutting blade having a replaceable cutting edge, the cutting edge being located on a replaceable blade cartridge. The blade comprises, in an exemplary embodiment, a main blade body  100  having a center axis  5  and a mounting hole  10  for mounting to a cutting device. The blade body has a trailing edge  110  and an outside edge  120 . Within the main blade body  100  there are receiving sections  150 . These sections receive the cartridge, as further explained below. The main blade body  100  also has a main blade body cutting edge  215  (as seen best in  FIG. 2 ). The replaceable cartridge body  200  has a corresponding cartridge outside edge  220 , cartridge tabs  270 , and a cartridge cutting edge  205 .  
         [0019]     In assembling the blade, the replaceable cartridge  200  is brought to the underside of the main blade body  100 . The cartridge tabs  270  are lined up with the receiving sections  150 . The cartridge tabs  270  are inserted into the receiving sections  150  and a locking mechanism  280  is engaged to secure the cartridge  200  in place. In the exemplary embodiment shown in  FIGS. 1-3  the locking mechanism  280  is a friction fit mechanism provided by a protrusion  285  on the cartridge tab  270  and corresponding detent  180  in receiving section  150  (as best see in  FIG. 3 ). Other locking mechanisms, such as slots, tabs, screws, glue, rivets, bolts and similar locking mechanisms can be provided without departing from the spirit of the invention. Similarly, the tabs  270  and receiving sections  150  can be reversed, so that the tabs protrude from the blade body  100  and the receiving sections  150  can be located in the cartridge  200  without departing from the spirit of the invention.  
         [0020]      FIG. 2  shows a side view from the outside edge of the main blade body of the exemplary embodiment of  FIG. 1  with the cartridge attached. The main blade body  100  is shown with replaceable cartridge  200  mounted thereto. The cutting edge  210  is comprised of the lead cutting edge  220  on the cartridge body  200  and the main body leading edge  215 . In further embodiments, as described herein below, the cutting edge  210  may comprise the entirety of the cutting edge of the blade system. A mounting shoulder  190  is provided to strengthen the support provided by the main blade body  100  to the replaceable cartridge  200 . During operation, the centrifugal force of the rotating cutting edge about the center axis  10  further push the replaceable cartridge  200  outwardly and into the friction fit locking mechanism  280  as provided. Additionally, the mounting shoulder  190  stiffens the cutting blade and provides additional support to the combination during operation and during any possible impact with obstructions.  
         [0021]      FIG. 3  shows a cross section of the exemplary embodiment of  FIG. 1  along line A-A with the replacement cartridge attached. The figure shows the main blade body  100  with the replaceable cartridge  200  mounted thereon. Cartridge tabs  270  are inserted into receiving section  150 . The cartridge tabs  270  are part of the locking mechanism  280 . A bulbous protrusion  285  extends from the surface of each of the cartridge tabs  270  that mates with the receiving section  150 . The receiving section  150  has a corresponding detent  155  which mates with the bulbous protrusion  285 . The two corresponding parts combine to form a friction fit locking mechanism, as bulbous protrusion  285  is forced over the portion of the receiving section  150  without the detent  155 . Alternative locking mechanisms can include but are certainly not limited to other shapes and components forming a friction lock, posts, rivets, screws, bolts, and similar securing mechanisms, and other locking mechanisms.  
         [0022]     In a further exemplary embodiment of the instant invention, a detent  305  is provided on the underside of main blade body  100 . The detent may be machined or coined into the main blade body  100 . The detent  305  is similar in size to the cartridge  200 , but slightly longer to accommodate the movement of the cartridge  200  during installation. The detent  305  allows for the cartridge  200  to be mounted flush to the main blade body  100 .  
         [0023]      FIG. 4  shows an additional cross section of another embodiment of the present invention. A main blade body  100  is shown with an upper blade surface  103  and a lower blade surface  107 . A replaceable cartridge  200  is slidingly coupled to the main blade body  100 . The replaceable cartridge  200  is engaged by a mounting shoulder  190 . The mounting shoulder  190  is shown with a rake angle  191 . The rake angle  191  is between about 0 and 45 degrees. The rake angle  191  within the mounting shoulder  190  significantly strengthens the operative connection of the replaceable cartridge  200  with the main blade body  100 , such that an impact will drive the replaceable cartridge  200  back into the main blade body  100 . Additionally, the locking mechanism  280 , here a rivet, is shown here as having a recess  283 , cut with angles  287 , 289 , so that the locking mechanism  280  has an upper portion  284  that is flush with upper surface  103  of the main blade body  100 . This aids in keeping the upper parts of the locking mechanism  280  from deteriorating due to wear. Additionally, the locking mechanism  280  also has a lower portion  286 , which is similarly configured to be flush with a lower surface of the replaceable cartridge  200 . In the exemplary embodiment shown in  FIG. 4  this is shown as, though is certainly not limited to, a recess in the lower surface of the replaceable cartridge  200  to accommodate the lower portion  286  of the locking mechanism  280 .  
         [0024]      FIGS. 5A and 5B  show a further cross section and top down view of another exemplary embodiment of the instant invention. In this embodiment the main blade body  100  is provided with a replaceable cartridge  200  having a cutting edge  210  and a mounting shoulder  190  with a slight rake angle  191  at the point of contact between the main blade body  100  and the mounting shoulder  190 , similar to the embodiment shown in  FIG. 4 . Additionally, a channel  500  is shown cut into the upper surface  103  of the blade body with a similar channel  502  cut into the lower surface  107 , aligned longitudinally with and offset from the channel  500  cut in the upper surface  103 .  
         [0025]     At each end of the channels  500 , 502 , T-slots  550 - 554  are cut within the ends of the channels  500 , 502 . The T-slots  550 - 554  are cut perpendicular to the channels  500 , 502  at each end. The T-slots  550 - 554 , as shown in  FIG. 5B , overlap at opposite ends on the channels  500 , 502  in the upper surface  103  and lower surface  107 , respectively. The T-slots  550 - 554  allow the head of a specially shaped installation tool (not shown) to enter or exit. The tool is shaped to fit in and runs within the channels  500 , 502 . The installation tool (not shown) is admitted through a T-slot (not shown) in the replaceable cartridge  200 , penetrates through the replaceable cartridge  200  and into a corresponding T-slot  550 - 554  at one end of the channel  500  or  502  and drives the replaceable cartridge  200  and the locking mechanism  280  within the channels  500 , 502  for the length of the channels  500 , 502 . The specially designed tool (not shown) is only capable of being removed once it reaches a pre-defined distance that corresponds to the distance for full installation of the replaceable cartridge  200 . Thus, the replaceable cartridge  200  is affirmatively driven by the tool to the proper installation position and friction fit in or mating within the main blade body  100 . Similarly the tool (not shown) will need to be inserted, driven, then fully removed by reversing the installation process and aligning the T-slots.  
         [0026]     The embodiments and examples discussed herein are non-limiting examples. The invention is described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the claims is intended to cover all such changes and modifications as fall within the true spirit of the invention.