Abstract:
A two piece peripheral mower blade is designed to cut and mulch grass at high volume. The blade is constructed of two pieces. The blades attach to a shaft via spaced apart hubs to which the pieces attach, and the two pieces of the blade interlock to provide a two piece peripheral mower blade.

Description:
PRIORITY CLAIM 
     The present application claims priority benefit of U.S. Provisional Patent Application No. 61/158,455 filed on Mar. 9, 2009. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to blades for grass mowers and agricultural implements, and, particularly to the improved two piece construction of a peripheral blade. 
     2. Discussion of the Prior Art 
     U.S. Pat. No. 5,375,400 to John A. Darden teaches a peripheral mower blade that is designed to cut and mulch grass at high volume. The blade is so designed to reduce back drag and require less horsepower. Such peripheral blades offer less chance that objects will be thrown out from under the mower deck they are mounted on, nor will they come apart creating a dangerous environment for those who are around the mower. In the construction discussed by Darden in &#39;400, the blade is one piece. At the time, Darden taught that a one piece blade made manufacture of the blade less expensive and made the blade more durable. 
     However, several drawbacks have been discovered with respect to the one piece peripheral mower blade. Such blades have been found time consuming and difficult to change. Since peripheral mower blades are mounted on a horizontal rotary shaft in a series containing several blades, all of the interim blades must be removed in order to replace a worn or damaged blade that is toward the center of the shaft. The one piece blades also require a series of spacers on the shaft separating the blades, and these spacers also must be dealt with when replacing or arranging the one piece peripheral blades on the shaft. 
     Thus, a need exists to improve peripheral mower blades to make them easier to install, especially when a blade on the center of the horizontal rotary shaft is damaged or worn. A two piece blade could be considered, but, before now, providing a two piece blade has been avoided and not seriously considered because of the belief that such blades would provide a weak structure and could break off of the shaft and present a danger of being slung outward from a mower. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective assembly view of the two piece peripheral cutting and mulching blade and horizontal rotary shaft of the present invention. 
         FIG. 1B  is a perspective assembly view of an alternative embodiment of the two piece blade and shaft of the invention. 
         FIG. 2  is a perspective view of the two piece peripheral cutting and mulching blade. 
         FIG. 3  is a side view of the blade of  FIG. 2 . 
         FIG. 4  is an enlarged perspective partial view of the blade of  FIG. 2 . 
         FIG. 5  is a side edge view of a mounting section of the blade of  FIG. 2  in accordance with the invention. 
         FIG. 6  is an enlarged section view of the blade at the location of line  6 - 6  of  FIG. 5  illustrating an aspect of an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The peripheral blade  10  of  FIG. 2  described is a two piece blade having two substantially triangular mounting sections  12 ,  14  comprising each piece. The main intent of this blade is the same as for one-piece peripheral blades: safety, less horsepower requirement, and lower maintenance cost. However, in this improved blade, the blade  10  is of a two piece construction, which makes installing and changing the blade much easier. Previously, it was considered that a two piece blade would lend itself to an increased chance of the blade flying apart, which would be hazardous to bystanders. The improvements to the peripheral blade  10  made and discussed herein provide a two piece peripheral blade that is safe to use. 
     When combined, the two pieces of the blade  10  with mounting sections  12 ,  14  provide an aperture  16  there though which a horizontal rotary shaft  18  can pass for mounting several of the two piece peripheral blades  10 . Each triangular mounting surface  12 ,  14  has two extended sides  20 ,  22  and  24 ,  26 , respectively, bent 90 degrees to the triangular mounting surface. One extended side is bent to the left and one to the right to form the blade section for cutting action. The bent extended sides  20 ,  22  and  24 ,  26  are parallel to the shaft  18  that will pass though the mounting aperture  16 . The combination of the two mounting sections  12 ,  14  provides a square with the mounting aperture  16  in the center. The square is measured diagonally to determine the blade&#39;s size, which is selected depending on the function and size of the peripheral blade  10  that is desired. The cutting edges  28  are along the front edge of the extended sides  20 ,  22  and  24 ,  26 . The length of the cutting edges  28  also depends on the desired size of the peripheral blade  10 . The trailing edge  30  of the cutting blade section is angled back to the mounting section  12  or  14  of the blade  10  for strength; the cutting edge  28  is not necessarily sharpened, but is hardened for wear. Each cutting blade section formed by the extended sides  20 ,  22  and  24 ,  26  has the general shape of a right triangle with each cutting edge of each surface being oriented perpendicular to the mounting surfaces, wherein said cutting blade sections each include a diagonal surface. The blade size may vary according to the use of the blade. For instance, a smaller blade is used for carpet grasses, and a larger blade is used for heavier grasses or agricultural implementations such as cutting cotton stalks. The blade thickness can vary in accordance to blade size and use. 
     The two-piece peripheral blade  10  is to be mounted on a horizontal rotary shaft  18  with a number of like two-part peripheral blades of the same size spatially mounted in series on the shaft. Thus, several sets of two triangular mounting sections  12 ,  14  form pairs that are provided to form each complete blade  10  needed. As shown in  FIGS. 1A and 1B , each blade  10  is separated on the shaft  18  by a space  32  that allows only about ½ inch of blade overlap. The space  32  between the blades may be provided by a spacer bushing  34  as shown in  FIG. 1A . An advantage of the two piece blade  10  of the present invention is the possible elimination of the spacer bushing  34  as shown in  FIG. 1B . As shown, two or more collars  36  for mounting the blades  10  are fixed, such as by welding, to the horizontal rotary shaft  18  in spaced relation to each other. The mounting sections  12 ,  14  of the blades  10  are attached to the side of each collar  36 . The process of mounting the blades  10  is repeated to attach additional pairs of mounting sections  12 ,  14  to each of the two or more collars  36  provided on the horizontal rotary shaft  18  until each collar has a blade attached thereto. The shaft  18  is to be rotated at high speed. The blades  10  rotate and cut toward the direction of travel. 
     The peripheral cutting and mulching blade  10  itself includes two pieces, in particular a pair of substantially triangular mounting sections  12 ,  14 . Each mounting section  12 ,  14  has an upper surface and lower surface, and each mounting section includes a first edge having a semi-circular cut-out  38  about a mid-point of the first edge. A second edge of each mounting section has a cutting blade edge  28  projecting perpendicular to the mounting section  12  or  14 , and a third edge having a cutting blade edge  28  projecting perpendicular to the mounting section  12  or  14 . The cutting blade edges  28  extend from the opposing surfaces of each mounting section  12  or  14 , whereby one of the cutting edges extends from the upper surface and one of them extends from the lower surface. The other mounting section  12  or  14  is identical to the first and includes identical extended cutting edges  28  that extend from the opposing surfaces. When the combination of both pieces of the two piece peripheral blade  10  are mounted on the horizontal rotary shaft  18 , a plurality of extended cutting edges  28  project perpendicular to the mounting sections  12  or  14 , thereby forming the peripheral blade  10  as a whole. Said peripheral blades  10  include cutting edges  28  and include two of which that extend from the upper surface on the mounting sections  12  or  14  of opposing peripheral blades and two cutting edges that extend from the lower surface on the mounting sections of opposing peripheral blades. 
     When triangular mounting sections  12 ,  14  are combined for placement on the shaft  18  via the circular collar  36 , the first edge of each mounting section abuts the other to form a central mounting aperture  16  from said semi-circular cut-outs. The mounting sections  12 ,  14  each include holes  40  for mounting the sections to the collar  36  to form the complete peripheral blade  10  on the shaft. The mounting sections  12 ,  14  are abutting as a pair against the collar, and the collars each include holes  42  for attachment of the mounting sections in which the holes align with those of the mounting sections. The first edge of the mounting sections  12 ,  14  includes a tabbed end  44  and a shallow deformed end  46 . When the sections  12 ,  14  are mounted on the collar  36 , the tabbed end  44  of each section overlaps the shallow deformed end  46  of each section of the abutting first edge of the other section as shown in  FIG. 4  and  FIG. 6 . Bolts  48  are inserted through the aligned holes  40  and  42  of the mounting sections and the collars to attach each pair of mounting sections  12 ,  14  to its respective collar  36 . When the abutting mounting sections  12 ,  14  are mounted on the collar  36 , the mounting sections interlock via the tabbed ends  44  overlapping the shallow deformations of the shallow deformed ends  46 . The interlocking of the mounting sections  12 ,  14  creates a complete two piece peripheral blade  10  in which the two parts do not slip and are not a hazard to separate or break apart. Through testing, the core mounting surfaces are found to be as secure as a one piece peripheral blade by the construction taught in the embodiments of the invention.