Abstract:
Attachable to a rotary lawnmower shaft is a body assembly of a rectangular shape having a removable and reversible blade on each end. The blades are easily and quickly removed, reversed, and replaced without tools. The blades are locked in position by a unique and simple locking device. During operation of the mower, the centrifugal force of the rotating body assembly further locks the blades in place for additional safety. When the body assembly is in rotation, the blades are designed to create air turbulence which causes the cut grass clippings to exit the lawnmower.

Description:
CROSS-REFERENCED TO RELATED APPLICATIONS 
   Not Applicable 
   FEDERALLY SPONSORED RESEARCH 
   Not Applicable 
   SEQUENCE LISTING OR PROGRAM 
   Not Applicable 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a rotary lawnmower blade and, more particularly, to a rotary lawnmower blade with removable reversible replaceable blades. 
   2. Background of the Invention 
   Rotary lawnmowers are by far the most common type of mower used by both the homeowner and the commercial operator. The blades on these mowers are in almost all cases a flat, rectangular steel bar, sharpened on the leading edges at each end of the bar to form a cutting edge. The frequency of use and the condition of the terrain mowed determines how often the blades dull and require sharpening. This task, which generally involves removing the blade from the mower, regrinding the cutting edges, balancing the blade and replacing it on the mower is a job the average homeowner doesn&#39;t want to do, resulting in taking the lawnmower to a professional shop for this service. 
   The most common approach taken to solve this problem is a blade assembly with detachable blades that can be removed, resharpened or replaced without removing the blade assembly from the lawnmower. Being of various designs, none of these seem to have been a commercial success and made available to the consumer, being of bad designs and too expensive to manufacture. 
   It is therefore an object of the present invention to provide a new and improved lawnmower blade assembly, consisting of a body assembly and two removable, reversible and reusable blades, that is economical to manufacture. 
   A further object of the present invention is the use of readily available materials to produce a durable blade assembly. 
   A further object of the present invention is to have the body assembly portion of the blade assembly to remain on the lawnmower while the blades are changed. 
   A further object of the present invention is in its design, allowing the changing of the blades without the use of tools. 
   A further object of the present invention is the ability to reverse the blades, resulting in exposing a new cutting edge. 
   A further object of the present invention is its design allows the changing of one blade or the changing of both blades. 
   A further object of the present invention allows the blades to be removed, resharpened and replaced. 
   A further object of the present invention allows the manufacturer to package the complete blade assembly or the blades individually, resulting in an advantage in cost and convenience for the consumer. 
   A further object of the present invention is the design allows for the manufacture of different size blade assemblies by increasing the length of the body (center section) of the blade assembly, resulting in tooling cost savings. 
   A further object of the present invention is the blade design being of a nature containing a grass turbulence surface area, creating an air disturbance of a centrifugal nature when the blade is in rotation as in mowing, resulting in the cut grass exiting the lawnmower. 
   A further object of the present invention is the fastening of the blade body to the lawnmower power shaft and it remaining in this position while the replaceable blades are changed. 
   A further object of the present invention is the unique design of the body assembly and blades and the procedure for removing and replacing the blades results in the blades locking to the body assembly. 
   A further object of the present invention is the blades being held on the body assembly by proper mechanical design and the centrifugal force created when the lawnmower is running, causing the blade assembly to rotate. 
   Further objects and advantages of my invention will become apparent from consideration of the drawings and ensuing description. 
   SUMMARY 
   The blade assembly for a rotary lawnmower described herein includes a body assembly being attached to the lawnmower power shaft. The body assembly contains two detachable cutting blades, each blade having two opposite cutting edges. Each blade is removable, reversible, and replaceable while the body assembly remains attached to the lawnmower power shaft. No tools are required for the removal and replacement of the blades. 

   
     DRAWINGS 
       FIG. 1  is a prospective view of the body. 
       FIG. 2  shows an exploded prospective view of pivot lock and body. 
       FIG. 3  is a view of  FIG. 2  showing pivot locks and body assembled. 
       FIG. 4  shows a perspective view of pivot lock. 
       FIG. 5  is a perspective view of blade. 
       FIG. 6  is a top orthogonal view of blade placed over pivot lock. 
       FIG. 7  is a sectional view of  FIG. 6  taken along lines  6 — 6 . 
       FIG. 8  is a perspective view of blade positioned on pivot lock in a 90° position to the longitudinal axis of the body. 
       FIG. 9  is a sectional view of  FIG. 8  taken along lines  8 — 8 . 
       FIG. 10  is a perspective view of the blade positioned on the pivot lock in a 90° position to the longitudinal axis of the body with arrow indicating movement of the blade. 
       FIG. 11  is a perspective view showing the locked or operating position of the blade on the body. 
       FIG. 12  is a perspective view of blade assembly. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1  what is shown is a right perspective view of a body  20  being of a rectangular shape and of sufficient length, width, and thickness. Centrally located in body  20  is center aperture  22  which is of sufficient diameter for mounting to a rotary lawnmower shaft. Located in body  20 , in proximity of left outer end  24  is aperture  26  and in proximity of right outer end  28  is aperture  30 . The diameters of aperture  26  and aperture  30  are of sufficient size as to accept locator boss  48  of pivot lock  42  as shown in  FIG. 4 . Aperture  26  and aperture  30  are centered longitudinally in body  20  in a predetermined equal distance from left outer end  24  and right outer end  28 . Centered longitudinally on aperture  26  of body  20  is a right cavity  32 . The width of right cavity  32  as shown in right cavity surface  34  is such as to accept the blade mounting end  52  of blade  50 . As shown in  FIG. 1  the right cavity  32  begins on the periphery of aperture  26  and extends laterally at a predetermined angle to the edge of body  20 . This area is represented by right cavity surface  34  and bounded on each end by a left end surface  36  and a right end surface  38  which form right angles to right cavity surface  34 . The left cavity  40  is an exact duplicate of right cavity  32 , it being located diametrically on the longitudinal plane of body  20 , being in the same relationship to aperture  30  as right cavity  32  is to aperture  26 . Refer to above description for details. 
   In  FIG. 2  we see body  20  in a right perspective view with projection lines emanating from aperture  26  and aperture  30  and showing proper assembly location of pivot locks  42  to body  20 . 
     FIG. 3  is a right perspective view of body assembly  18 , showing pivot locks  42  assembled in aperture  26  and aperture  30  (see  FIG. 2 ). The correct assembly is accomplished by inserting locator boss  48  (see  FIG. 2 ) in aperture  26  and aperture  30  (see  FIG. 2 ). Locator boss  48  and aperture  26  and aperture  30  (see  FIG. 2 ) being of a size that results in an interference fit. The pivot bosses  46  are in horizontal contact with body  20  and the horizontal axis of lock bars  44  are at a right angle to the longitudinal axis of body  20 . The locator bosses  48  (see  FIG. 2 ) are now industrially fastened (such as welding) to body  20 . 
     FIG. 4  depicts the pivot lock  42  which is preferably fabricated from metal suitable to heat treating to obtain durability. The lock bar  44  is of an elongated rectangular shape of a predetermined size. The pivot boss  46  being an integral part of the lock bar  44  is centrally located on the lock bar&#39;s  44  longitudinal axis. The locator boss  48  is of a cylindrical shape with the diameter and thickness being of a predetermined size. Centrally connected to and being a part of the pivot boss  46  is the locator boss  48 . The locator boss  48  is of a size as to create an interference fit in aperture  26  and aperture  30  of body  20  shown in  FIG. 2 . 
     FIG. 5  is a perspective view of blade  50  which can be fabricated by accepted industrial methods from a variety of metals and plastics. The preferred material being steel suitable to heat treating or case hardening. The blade&#39;s  50  thickness is such that it falls within the parameters of industry accepted blade thicknesses. The length of blade  50  is made by calculations that take into consideration the body  20  ( FIG. 1 ) length and industry standard lengths for mower blades. The blade mounting end  52  of the blade  50  is of the same width as the body  20  of  FIG. 1 . The length of the blade mounting end  52  is such as to allow left cutting edge  54  and right cutting edge  56  to clear the body  20  ( FIG. 1 ) during assembly. A blade cutting end surface  58  is a longitudinal continuation of the blade mounting end  52 . 
   The blade cutting end surface  58  contains a grass turbulence left surface  60  and the grass turbulence right surface  62 . The grass turbulence left surface  60  is formed by bending blade  50  downward to a predetermined suitable angle along a line continuation of the left edge  64 . A left cutting edge surface  68  is created by bending the blade  50  on a predetermined line running parallel with grass turbulence left surface  60 , and causing left cutting edge surface  68  to be in lateral parallelism with the blade cutting end surface  58 , the left cutting edge surface  68  being beveled to form left cutting edge  54 . Referring to grass turbulence right surface  62  being created by bending blade  50  upward to a predetermined suitable angle along a line continuation of right edge  66 . A right cutting edge surface  70  is created by bending the blade  50  on a predetermined line running parallel with grass turbulence right surface  62  and causing the right cutting edge surface  70  to be in lateral parallelism with the blade cutting end surface  58 , the right cutting edge surface  70  being beveled to form right cutting edge  56 . 
   A blade aperture  72  is located in the blade mounting end  52  of blade  50  in a central location between left edge  64  and right edge  66 . Its longitudinal location is such that allows left cutting edge  54  and right cutting edge  56  to clear the body  20  during assembly as shown in  FIG. 8 . The blade aperture  72  diameter is of a size that when assembled on pivot boss  46  ( FIG. 4 ) the blade  50  will freely pivot. A blade slot  74  being of a predetermined width and length and being on the longitudinal centerline and in connection with blade aperture  72  and oriented in the direction of the blade cutting end surface  58 . 
     FIG. 6  is a top orthogonal view of blade  50  and body assembly  18 . The blade  50  is shown with blade aperture  72  positioned under pivot lock  42  and in contact with pivot boss  46 . The blade mounting end  52  is centered in the right cavity  32  and is in physical contact with the right cavity surface  34 . This results in the blade  50  being at a right angle to the body assembly  18  when viewed in the vertical plane ( FIG. 6 ) and at an acute angle when viewed in the horizontal plane ( FIG. 7 ). 
     FIG. 7  is a sectional view taken at lines  7 — 7  of  FIG. 6 . This view shows  FIG. 6  in greater detail. 
     FIG. 8  is a left top perspective view depicting the blade  50  with blade aperture  72  and blade slot  74  assembled over the pivot lock  42  and the pivot boss  46 . The blade  50  is in parallelism with body assembly  18 . 
     FIG. 9  is a sectional view along lines  9 — 9  of  FIG. 8  showing blade  50  and body assembly  18  for clarity. 
     FIG. 10  is a left top perspective view and the same view as  FIG. 8  with the addition of the arrow indicating the movement of blade  50 . 
     FIG. 11  is a top perspective view depicting the blade  50  position resulting in the blade  50  movement indicated by the arrow in  FIG. 10 . The blade  50  is in its final or mowing position. 
     FIG. 12  is a perspective view depicting the body assembly  18  with blades  50  assembled on both ends in the mowing position. 
   OPERATION OF PREFERRED EMBODIMENT 
   The preferred embodiment of  FIG. 12  is of the parts being shown in assembly. The design of body assembly  18  causes the blades  50 , which are of symmetrical design, to result in the cutting edges  54  being diametrically opposed. The body assembly  18  via center aperture  22  is bolted to a rotary powered lawnmower shaft that when viewed from the top rotates the body assembly  18  in a clockwise direction, causing cutting edges  54  to contact, cut and exit the grass from the mower. 
   The blades  50  ( FIG. 5 ) are assembled to the body assembly  18  ( FIG. 3 ) in the following manner. The blade aperture  72  and blade slot  74  ( FIG. 5 ) are placed over pivot lock  42  and pivot boss  46  ( FIGS. 4 ,  6 ) until blade mounting end  52  ( FIG. 5 ) comes into contact with the right cavity surface  34  ( FIG. 6 ). This results in the blade  50  being in an acute angle to the body assembly  18 . The blade  50  is now slid parallel with the right cavity surface  34  until blade aperture  72  contacts pivot lock  42  ( FIG. 7 ). The blade  50  can now be moved downward, causing blade aperture  72  and blade slot  74  to clear lock bar  44  and pivot boss  46 , this being shown more clearly in  FIGS. 8 and 9 . The blade  50  is now in parallel contact with body assembly  18  ( FIGS. 8 ,  9 ) and can now be rotated to its mowing position shown in  FIG. 11 . The blade  50  now being in its correct mowing position causes the blade slot  74  to be in a right angular position to the lock bar  44  and causing the blade  50  to be locked to the body assembly  18 . To remove the blade  50  from the body assembly  18  the above reverse procedure is performed. The blade  50  ( FIG. 5 ) is of a symmetrical design with a left cutting edge  54  and a right cutting edge  56  ( FIG. 5 ). When the blade  50  ( FIG. 5 ) is removed from the body assembly  18  ( FIG. 11 ) and rotated 180° about its longitudinal axis and replaced on the body assembly  18  ( FIG. 1 ) a new cutting edge  56  is in proper placement for cutting grass. The foregoing procedure is used to replace, remove, and reverse blades  50 . 
   Thus the reader will see that the blade assembly is easily attachable to the lawnmower, simple to change the detachable and reusable blades, economical to manufacture, and can be used by persons regardless of their mechanical ability. 
   While my above description contains many specifications, these should not be construed as limitations on the scope of the invention, but rather as an exemplification of one of the preferred embodiments thereof. Other variations are possible. For example:
         Changing of the physical dimensions   Using different materials       

   Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but the appended claims and their legal equivalents.