Abstract:
A method of manufacturing shredder blades which improves efficiency and a new structure for a shredder blade or blade pair.

Description:
BACKGROUND 
       [0001]    The present invention is generally directed to shredders and, more specifically, to shredder blades and to methods of producing shredder blades in which fabrication of shredder blades and assembly into shredder blade pairs is performed in a single manufacturing stage. 
         [0002]    The normal operation of a shredder generally entails directing material to be shredded between two sets of shredder blades arranged along two parallel axles. The shredder blades along opposite axles are interlaced with overlapping radii, and a cutting surface is formed at the interface of the two opposing sets of blades. There are two types of shredders, strip-cut shredders and cross-cut shredders. A strip-cut shredder divides the shredded material into long strips, and requires blades of a generally round shape. A cross-cut shredder also cuts the shredded material laterally to separate the shredded material into strips of shorter length. A cross-cut shredder generally places greater stress on the shredder blades and the shredder axle which may result in some conventional shredder blades deforming and malfunctioning. 
         [0003]    Manufacturing the shredder blades generally involves cutting each blade into the preferred shape. The width of each conventional blade is generally equal to the thickness of the sheet metal. Spacers may be located along each shredder axle to provide distance between adjacent blades to allow interlacing of blades on opposing axles. 
         [0004]    It may be advantageous to manufacture a shredder blade having an improved configuration for use in a shredder or to manufacture shredder blade pairs that have sufficient structural rigidity, that can be manufactured at a reduced cost, and/or that can be manufactured as part of a running manufacturing process. 
       SUMMARY 
       [0005]    Briefly speaking, the present invention is directed to a method of producing shredder blades during assembly of a shredder. Sheet metal is sent into a processing station and moves continuously through the station. While the sheet metal is moving through the station, it is stamped to form first and second shredder blades. The first and second shredder blades continue to move through the processing station and are riveted together to form a blade pair adapted for use in a shredder. This processing station is part of a continuously running manufacturing process for producing a plurality of blade pairs from sheet metal. 
         [0006]    In another aspect, the invention is directed to a blade pair adapted for use in a shredder. Each of the first and second blades of the blade pair has a major mating surface, a sidewall extending generally outward from the major mating surface, and a plurality of cutting teeth. In the assembled blade pair, the cutting teeth of the first and second blades are aligned, and the inner surfaces of adjacent teeth form an angle of between eighty (80) degrees to ninety (90) degrees. 
         [0007]    In another aspect, the invention is directed to a method of producing shredder blades during assembly of a shredder. Sheet metal is sent into a processing station and moves continuously through the station. While the sheet metal is moving through the station, it is stamped to form first and second shredder blades. Each of the first and second blades of the blade pair has a major mating surface, a sidewall extending generally outward from the major mating surface, and a plurality of cutting teeth. The first and second shredder blades continue to move through the processing station and are riveted together to form a blade pair adapted for use in a shredder. In the assembled blade pair, the cutting teeth of the first and second blades are aligned, and the inner surfaces of adjacent teeth form an angle of between eighty (80) degrees to ninety (90) degrees. This processing station is part of a continuously running manufacturing process for producing a plurality of blade pairs from sheet metal. 
         [0008]    In a separate aspect, the invention is directed to a method of producing shredder blades during assembly of a shredder. Sheet metal is sent into a processing station and moves continuously through the station. While the sheet metal is moving through the station, it is stamped to form first and second shredder blades. Each of the first and second blades of the blade pairs have a major mating surface, a sidewall extending generally outward from the major mating surface, and a plurality of cutting teeth. The first shredder blade is stamped with a plurality of tubes that extend past the major mating surface of the blade and are configured to serve as a rivet. The second shredder blade is stamped with a plurality of bores on the major mating surface which accommodate the tubes of the first blade. The first and second shredder blades continue to move through the processing station and in a continuous process the tubes of the first shredder blade are inserted into the bores of the second blade and are bent to rivet the first and second blades together. In the assembled blade pair, the cutting teeth of the first and second blades are aligned, and the inner surfaces of adjacent teeth form an angle of between eighty (80) degrees to ninety (90) degrees. This processing station is part of a continuously running manufacturing process for producing a plurality of blade pairs from sheet metal. 
         [0009]    In another aspect, one embodiment of the present invention is directed toward a method of producing shredder blades, including: transporting material through a first processing station in a continuous fashion; while the material is moving through the first processing station, forming at least a portion of the material to generate first and second shredder blades from the material; and while the first and second shredder blades are moving through the first processing station, joining the first and second shredder blades together to form a blade pair adapted for use in a shredder, wherein the forming and joining both occur in the first processing station to allow first and second shredder blades to be formed from material and joined together to form the blade pair as part of a continuously running manufacturing process for producing a plurality of blade pairs from material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The foregoing summary, as well as the following detailed description of the preferred embodiments of the present invention will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It is understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: 
           [0011]      FIG. 1  is a perspective view of an exemplary shredder that incorporates shredder blades according to a preferred embodiment of the present invention; a plurality of shredder blade pairs may be located along two parallel shredder axles and are preferably oriented such that material inserted into one of the two slots passes between the two shredder axles and is shredded by the rotating movement of the plurality of shredder blade pairs; 
           [0012]      FIG. 2  is a perspective view of preferred first and second shredder blades which can be joined (via riveting or the like) to form a blade pair and are preferably incorporated into a shredder or stored for later use; the dashed line shows the path along which the shredder blades are moved during assembly; 
           [0013]      FIG. 3  is a perspective view of the two shredder blades which can be riveted to form a blade pair and incorporated into a shredder; each tube of the first blade may be inserted into a matching bore of the second blade to orient the major mating surface of the first shredder blade adjacent to the major mating surface of the second shredder blade; 
           [0014]      FIG. 4  is a perspective view of the assembled blade pair which may be incorporated into a shredder; each tube of the first blade may be bent to form a rivet which holds the two blades together; 
           [0015]      FIG. 5  is a perspective view of a plurality of shredder blade pairs in their location along the two parallel shredder axles in the shredder of  FIG. 1 ; the shredder blades are interlaced and each cutting surface of a shredder blade pair is matched with the cutting surface of a shredder blade pair on the opposite axle; 
           [0016]      FIG. 6  is a top plan view of a portion of the interface between shredder blade pairs on opposite shredder axles in the shredder of  FIG. 1 ; the figure illustrates spacers which keep the blades on each axle in an optimal interlaced position; 
           [0017]      FIG. 7  is a perspective view of a part of a preferred first processing station according to a preferred embodiment of the present invention; the sheet metal travels left to right across the figure, and the following sequence of processing steps preferably occurs; First, the outline of each of the two blades is stamped into the sheet metal; Then the metal of each blade is punched and stamped to form shredder axle holes, tubes, and/or bores, depending on the shredder blade being processed; Then, each of the two blades is punched out of the sheet metal and drops into its receiving mold block; 
           [0018]      FIG. 8  is a perspective view of a part of the preferred first processing station of  FIG. 7 ; the mold blocks preferably, but not necessarily, move left to right across the figure and rotate to place the first shredder blade on an anvil and the second shredder blade on an arbor; 
           [0019]      FIG. 9  is a perspective view of a part of the preferred first processing station of  FIG. 7 ; the anvil and arbor bring the first and second blades together, and the tubes of the first blade are inserted into the bores of the second blade and bent to rivet the first and second blades together; the arbor is removed to leave the riveted blade pair on the anvil, which then advances the blade pair onto a mandrel or any other suitable receptacle; the mandrel may hold the blade pair to allow a pair of grinding wheels to grind the blade pair to the correct width or sharpen the blade edges; 
           [0020]      FIG. 10  is a cross-sectional view of the anvil, arbor and first and second shredder blades of  FIG. 8  as taken along the line  10 - 10  in  FIG. 8 ; one of the tubes of the first shredder blade is shown in cross section, as are the corresponding bore in the second shredder blade and the portion of the arbor which bends the tube into a rivet; 
           [0021]      FIG. 11  is a cross-sectional view of the anvil, arbor and joined shredder blade pair of  FIG. 9  as taken along the line  11 - 11  in  FIG. 9 ; one of the tubes of the first shredder blade is shown in cross section, and it extends through the corresponding bore in the second shredder blade and has been bent by the arbor into a rivet which joins the blades together; 
           [0022]      FIG. 12  is a flowchart of one preferred method for producing shredder blade (or cutter) pairs in the processing station of  FIGS. 7-11  or using any other suitable processing arrangement; the shredder blades are moved from the mandrel to the shredder axle (or drive axle) in a step outside the processing station shown in these figures; and 
           [0023]      FIG. 13  is a flowchart of another preferred method for producing shredder blade pairs and mounting them onto the shredder axle according to another preferred embodiment of the present invention; in this embodiment, the anvil advances the blade pair directly onto the shredder axle. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Certain terminology is used in the following description for convenience only and is not limiting. The words “right,” “left,” “top,” and “bottom” designate directions in the drawings to which reference is made. The words “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the shredder and designated parts thereof. The term “selectable control”, as used in the claims and the corresponding portions of the specification, means “any one of a physical switch, a touch switch, a button, a voice activated switch, a control knob, a remote control switch, or any other known operating mode selection device”. The term “activated state”, as used with selectable control, means that the selectable control has been manipulated so that the selectable control is set for a particular function. For example, if the selectable control is a simple switch, then the activated state may be having the switch turned to another position and if the selectable control is a touch sensor, then the activated state may be initiated by depressing or touching the sensor in a predetermined manner. The language “at least one of ‘A’, ‘B’, and ‘C’,” as used in the claims and in corresponding portions of the specification, means “any group having at least one ‘A’; or any group having at least one ‘B’; or any group having at least one ‘C’;—and does require that a group have at least one of each of ‘A’, ‘B’, and ‘C’.” Additionally, the words “a” and “one” are defined as including one or more of the referenced item unless specifically stated otherwise. The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import. 
         [0025]    Referring to  FIGS. 1-13 , wherein like numerals indicate like elements throughout, there are shown preferred embodiments of improved shredder blades  40 A,  40 B and methods of producing shredder blades that improve the manufacturing process. While the methods are preferably used with the improved shredder blades  40 A,  40 B, they can be used to manufacture blades of any configuration without departing from the scope of the present invention. 
         [0026]    Referring to  FIG. 1 , one exemplary shredder  22  is shown. The shredder  22  includes a shredder head  26  which defines at least one slot  32 ,  34  that is adapted to receive material to be shredded. The shredder head  26  is incorporated into a shredder housing  24  with lateral sides  38 , and a basket  12  is removeably positioned in the shredder housing  26  for collection of shredded material and comprises the greater part of the front  36  of the shredder  22 . The basket includes a transparent section  18  which allows a user to visually determine when the bin must be emptied for continued optimal shredder operation. Wheels  16  located at the bottom of the shredder housing  24  allow the shredder to be rolled into a desired location, and handles  14  allow the shredder to be moved vertically over obstacles in the rolling path. While one preferred configuration for a shredder incorporating blades of the present invention has been shown and described, those of ordinary skill in the art will appreciate that the blades  40 A,  40 B of the present invention and the methods of producing blades of the present invention can be used with any suitable shredder or to just manufacture shredder blades that may later be incorporated into a shredder. 
         [0027]    The shredder may be powered by an electrical connection/power conduit  28 , and when electrical power is delivered to the shredder a selectable control  30  on the shredder head allows a user to set the shredder to either operate continuously or activate when material is placed into one of the slots  32 ,  34 . Indicators  20  on the shredder head alert a user to any condition that would interfere with continued shredder operation such as an overloaded bin or an automatic reverse in progress. Additional controls  15  allow the user to make adjustments to shredder performance appropriate to the material to be shredded. A plurality of shredder blades  10  are disposed within the shredder head  26  and are adapted to shred the material inserted into one of the slots  32 ,  34  and eject it into the basket  12 . The first slot  32  is preferably used for paper documents and the second slot  34  is preferably used for more rigid documents, such as credit cards, compact discs, etc. 
         [0028]    The shredder housing  24  and basket  12  of the present invention are preferably constructed of a polymer for maximum rigidity. However, the shredder can be constructed of any suitable material without departing from the scope of the present invention. 
         [0029]    Referring still to  FIG. 1 , while the preferred shredder  22  has a generally rectilinear shape, those of ordinary skill in the art will appreciate from this disclosure that the shredder  22  can have any shape without departing from the scope of the present invention. The top and/or side surfaces of the shredder may also include other operational indicators  15 . While one exemplary shredder has been described in conjunction with  FIG. 1 , those of ordinary skill in the art will appreciate from this disclosure that the present invention can be practiced with shredders of any configuration without departing from the scope of the present invention. 
         [0030]    Referring to  FIG. 2 , each of the first shredder blade  40 A and the second shredder blade  40 B may have a shredder axle bore  44 , a major mating surface  48 , a sidewall  50  extending generally outwardly therefrom, and three cutting teeth  56  with first cutting surface  56 A and second cutting surface  56 B. The number of cutting teeth  56  may vary without departing from the scope of the present invention. Each cutting tooth  56  extends from a flat  58  and the second cutting surface  56 B is adjacent to the flat  58  along the sidewall  50 . The sidewall  50  and the major mating surface  48  preferably form an angle  60  of between one hundred (100) degrees and one hundred twenty (120) degrees. It is more preferred that the angle between the sidewall and the major mating surface form an angle  60  of approximately one hundred ten and a half (110.5) degrees. It is preferred that the height of the sidewall  50  is between one (1) millimeter and one and a half (1.5) millimeters. It is more preferred that the height of the sidewall  50  is approximately one point three (1.3) millimeters. The first shredder blade  40 A includes three tubes  42 , and the second shredder blade  40 B includes three bores  46  which are of the same diameter as the outside surface of the tubes  42  of the first shredder blade  40 A. Each of the tubes  42  and the bores  46  are preferably located inwardly from one of the three cutting teeth  56 . The number of tubes  42  and bores  46  may vary without departing from the scope of the present invention. The cutting tooth  46  and flat  58  preferably form an angle  62  of between eighty (80) and one hundred (100) degrees. It is more preferred that the cutting tooth  46  and flat  58  form an angle  62  of approximately ninety (90) degrees. The angle formed by the sidewall  50  at the end of the cutting tooth is preferably between thirty-five (35) and forty-five (45) degrees. It is more preferred that the angle formed by the sidewall  50  at the end of the cutting tooth is approximately forty (40) degrees. 
         [0031]    Referring to  FIG. 3 , the first and second shredder blades  40 A,  40 B are brought into contact to form a blade pair  52 . Each tube  42  of the first shredder blade  40 A extends through a bore of the second shredder blade  40 B, and the entire major mating surface  48  of the first shredder blade  40 A is preferably in contact with the entire major mating surface  48  of the second shredder blade  40 B. In this position, the shredder axle bore  44  on the first shredder blade  40 A is aligned with the shredder axle bore  44  on the second shredder blade  40 B. The angle  54  formed by the sidewalls  50  at the end of each cutting tooth  56  is preferably between eighty (80) and ninety (90) degrees. It is more preferred that the angle  54  formed by the sidewalls  50  at the end of each cutting tooth  56  is approximately eighty-six ( 86 ) degrees. 
         [0032]    Referring to  FIG. 4 , each tube  42  of the first shredder blade  40 A is bent to form a rivet about the bore  46  of the second shredder blade  40 A. In the riveted configuration, it is preferred that the blade pair  52  has a width between one point five (1.5) and five (5) millimeters. It is more preferred that the blade pair  52  has a width between two (2) and three (3) millimeters. It is still more preferred that the blade pair  52  has a width of approximately two point six (2.6) millimeters. 
         [0033]    While it is preferred that the shredder blades  40 A,  40 B are riveted together, any suitable joining method (such as welding) can be used without departing from the scope of the present invention. Furthermore, although a preferred shredder blade structure has been described, the methods of the present invention can be used to form shredder blades having any configuration without departing from the scope of the present invention. Furthermore, the method of the present invention can be used to join together three or more shredder blades to form a blade pair  52 . 
         [0034]    Referring to  FIGS. 5 and 6 , each blade pair  52  is located along one of the two shredder axles  64 , with the shredder axle  64  passing through the shredder axle hole  44  of each blade pair  52 . Each blade pair  52  is separated along the axle  64  from its adjacent blade pairs by a spacer  66 . Along each shredder axle  64 , the spacers  66  position the blade pairs  52  such that they are interlaced with the blade pairs  52  on the opposite axle. On each blade pair  52 , the first cutting surface  56 A of each cutting tooth  56  is matched with the first cutting surface  56 A of a blade pair  52  on the opposite axle. 
         [0035]    Referring to  FIGS. 7-11 , wherein like numerals indicate like elements throughout, there are shown a preferred embodiment of a preferred blade pair processing station. It is preferred that this station both forms the shredder blades  40 A,  40 B and assembles them into a blade pair. Briefly speaking, the blade pair assembly station takes in sheet metal  68  and produces assembled blade pairs  52  which are placed on a mandrel  64 B (or placed in/on any suitable collection mechanism or container) and possibly ground to the correct width by grinding wheels  86 . While it is preferred to use sheet metal  68 , those of ordinary skill in the art will appreciate from this disclosure that any suitable material can be used to form the shredder blades  40 A,  40 B without departing from the scope of the present invention. 
         [0036]    Referring to  FIG. 7 , the sheet metal  68  travels generally continuously left to right across the figure. In the preferred sequence, the shape of each of the two shredder blades  40 A,  40 B is stamped into the sheet metal  68 , defining the major mating surface  48  and the sidewalls  50  on each shredder blade. As the sheet metal  68  continues left to right, the shape of the left shredder blade  40 A is punched to form a shredder axle hole  44  and is stamped to form three tubes  42  which will function as rivets in the finished shredder blade pair. The shape of the right shredder blade  40 B is punched to form a shredder axle hole  44  and three bores  46  which match the three tubes  42 . Each of the two shredder blades  40 A,  40 B is punched out of the sheet metal  68  and drops into its receiving mold block  76 . The receiving mold block  76  is attached to the base  78  at a pivot  80 . 
         [0037]    Referring to  FIG. 8 , the base  78  preferably moves generally continuously left to right across the figure to allow the shredder blades  40 A,  40 B to move along the same general path as the sheet metal if desired. Each of the receiving mold blocks  76  rotates about the pivot  80  to a vertical orientation. The anvil  82  and arbor  84  move generally continuously left to right across the figure, and when the receiving mold blocks  76  reach a vertical orientation, the first shredder blade  40 A is put onto the anvil  82 , and the second shredder blade  40 B is put onto the arbor  84 . The receiving mold blocks  76  then return to a horizontal position leaving a clear path between the anvil  82  and arbor  84 . 
         [0038]    Referring to  FIG. 9 , the anvil  82  and arbor  84  move generally continuously left to right across the figure. The arbor  84  moves towards the anvil  82  and presses the major mating surface  48  of the second shredder blade  40 B against the major mating surface  48  of the first shredder blade  40 A. Each of the three tubes  42  of the first shredder blade  40 A extends through one of the three bores  46  in the second shredder blade  40 B. The arbor  84  is adapted to bend the tubes  42  to form rivets which hold the blade pairs together. After the rivets are formed, the arbor  84  withdraws from the anvil  82 , and the anvil carries the riveted blade pair  52  onto the mandrel  64 B. Once the blade pair  52  is in position on the mandrel  64 B, a pair of grinding wheels  86  may engage the blade pair  52  and rotate to grind the blade pair  52  to the required width and sharpen the first cutting surface  56 A of each tooth. As the grinding wheels  86  turn, the mandrel  64 B also turns to bring the entire perimeter of the blade pair to the grinding wheels  86 . When grinding is complete, the blade pair may be moved towards the end of the mandrel  64 B to await placement onto the shredder axle  64 A. 
         [0039]    Referring to  FIG. 10 , the anvil  82  holds the first shredder blade  40 A, and the arbor  84  holds the second shredder blade  40 B as shown in  FIG. 8 . The tubes  42  extend from the major mating surface  48  of the first shredder blade  40 A. The bores  46  are of the same diameter as the external diameter of the tubes  42 , and the arbor  84  includes a hollowed area which accommodates the tubes  42  as they extend past the bore  46  in the second shredder blade  42 B. 
         [0040]    Referring to  FIG. 11 , the arbor  84  presses the second shredder blade  40 B against the first shredder blade  40 A as shown in  FIG. 9 . The tubes  42  extend past the bore  46  into a hollowed area of the arbor  84 , and are bent into a rivet that joins the first and second shredder blades  40 A,  40 B into a shredder blade pair  52 . 
         [0041]    Multiple preferred methods of the present invention will be described below (alone or in combination with various embodiments of the shredder blades). The steps of the methods of the present invention can be performed in any order, omitted, or combined without departing from the scope of the present invention. As such, optional or required steps described in conjunction with one method can also be used with another method or omitted altogether. Additionally, unless otherwise stated, similar structure or functions described in conjunction with one method preferably, but not necessarily, operate in a generally similar manner to that described elsewhere in this application. 
         [0042]    One preferred method of producing shredder blades  40 A,  40 B includes transporting sheet metal  68  through a processing station. While the sheet metal  68  is moving through the station, it is stamped to form first and second shredder blades  40 A,  40 B. The first and second shredder blades  40 A,  40 ,B continue to move through the processing station and are riveted (or otherwise secured) together to form a blade pair adapted for use in a shredder. This processing station is part of a continuously running manufacturing process for producing a plurality of blade pairs from sheet metal. 
         [0043]    Another preferred method of the present invention is directed to a method of producing shredder blades  40 A,  40 B including the steps of: transporting sheet metal  68  through a first processing station in a generally continuous fashion. While the sheet metal  68  is moving through the first processing station, stamping the sheet metal  68  to form first and second shredder blades  40 A,  40 B from the sheet metal  68 . While the first and second shredder blades  40 A,  40 B are moving through the first processing station, riveting (or otherwise joining) the first and second shredder blades  40 A,  40 B together to form a blade pair  52  adapted for use in a shredder. Wherein the stamping and riveting both occur in the first processing station to allow first and second shredder blades  40 A,  40 B to be stamped from sheet metal and riveted together to form the blade pair  52  as part of a generally continuously running manufacturing process for producing a plurality of blade pairs  52  from sheet metal  68 . 
         [0044]    Another preferred method of the present invention is directed to making a blade pair  52  adapted for use with a shredder including first and second shredder blades  40 A,  40 B each having a major mating surface  48 , a sidewall  50  extends generally outwardly therefrom, and a plurality of cutting teeth. The cutting teeth of each of the first and second shredder blades  40 A,  40 B are generally aligned so that inner surfaces of adjacent teeth are oriented to form an angle  54  of between eighty (80) degrees to ninety (90) degrees therebetween. 
         [0045]    Another preferred method of producing shredder blades includes: transporting sheet metal  68  through a first processing station in a generally continuous fashion; while the sheet metal  68  is moving through the first processing station, stamping the sheet metal  68  to form first and second shredder blades  40 A,  40 B from the sheet metal  68 . The first and second shredder blades each having a major mating surface  48 , a sidewall  50  extending generally outwardly therefrom, and a plurality of cutting teeth. The cutting teeth of each of the first and second shredder blades  40 A,  40 B are generally aligned so that inner surfaces of adjacent teeth are oriented to form an angle  54  of between eighty (80) degrees to ninety (90) degrees therebetween when the first and second shredder blades  40 A,  40 B are assembled to form a blade pair  52 . The method further includes while the first and second shredder blades  40 A,  40 B are moving through the first processing station, riveting the major mating surface  48  of the first and second shredder blades  40 A,  40 B together to form a blade pair  52  adapted for use in a shredder. The stamping and riveting both occur in the first processing station to allow first and second shredder blades  40 A,  40 B to be stamped from sheet metal and riveted together to form the blade pair  52  as part of a generally continuously running manufacturing process for producing a plurality of blade pairs  52  from sheet metal  68  (or any other suitable material). 
         [0046]    Referring to  FIG. 12 , one preferred method for producing shredder blade pairs  52  in the processing station of  FIGS. 7-11  is described. In the first step, the sheet metal  68  is stamped to form the cutter shapes for the first and second shredder blades  40 A,  40 B, including the sidewalls  50 . In the second step, the sheet metal  68  for the first shredder blade  40 A is punched to create the axle hole  44 , and stamped to form the three tubes  42 , each of which forms a rivet. The sheet metal for the second shredder blade  40 B is punched to add the axle hole  44  and the three bores  46  which will accommodate the three tubes  42  of the first shredder blade  40 B. In the third step, the sheet metal  68  is punched to cut the first and second shredder blades  40 A,  40 B from the sheet metal  68 , and the shredder blades  40 A,  40 B are placed into the receiving mold block  76 . The mold block  76  rotates to position the first and shredder blades  40 A,  40 B onto a common axis, and the arbor  84  and anvil  82  receive the two shredder blades. The arbor  84  presses the second shredder blade  42 B onto the first shredder blade  42 A, and forms rivets which fasten the two shredder blades  42 A,  42 B into a blade pair  52 . The anvil  82  advances the blade pair  52  onto the mandrel  64 B, which holds and rotates the blade pair  52  while grinding wheels  86  cut the edges of the blade pair  52  to a precise width. The finished blade pair  52  advances and the mandrel  64 B continues to receive and finish blade pairs  52 . The steps above repeat until the mandrel  64 B has a full complement of finished shredder blade pairs  52 , and the mandrel  64 B advances to the next assembly station. The finished blade pairs  52  are then removed from the mandrel  64 B and assembled onto the shredder axle  64 A with the addition of spacers  66 . 
         [0047]    Referring to  FIG. 13 , another preferred method for producing shredder blade pairs  52  and mounting them onto the shredder axle  64 A is described. In the first step, the sheet metal  68  is stamped to form the cutter shapes for the first and second shredder blades  40 A,  40 B, including the sidewalls  50 . In the second step, the sheet metal  68  for the first shredder blade  40 A is punched to create the axle hole  44 , and stamped to form the three tubes  42 , each of which forms a rivet. The sheet metal for the second shredder blade  40 B is punched to add the axle hole  44  and the three bores  46  which will accommodate the three tubes  42  of the first shredder blade  40 B. In the third step, the sheet metal  68  is punched to cut the first and second shredder blades  40 A,  40 B from the sheet metal  68 , and the shredder blades  40 A,  40 B are placed into the receiving mold block  76 . The mold block  76  rotates to position the first and shredder blades  40 A,  40 B onto a common axis, and the arbor  84  and anvil  82  receive the two shredder blades. The arbor  84  presses the second shredder blade  42 B onto the first shredder blade  42 A, and forms rivets which fasten the two shredder blades  42 A,  42 B into a blade pair  52 . The anvil  82  advances the blade pair  52  onto the shredder axle  64 A, and a spacer  66  is added following the blade pair  52 . The shredder axle  64 A holds and rotates the blade pair  52  while grinding wheels  86  cut the edges of the blade pair  52  to a precise width. The finished blade pair  52  and spacer  66  advance and the shredder axle  64 A continues to receive and finish blade pairs  52 . Once the shredder axle  64 A has a full complement of shredder blade pairs  52 , it proceeds to the next assembly station. 
         [0048]    It is recognized by those skilled in the art that changes may be made to the above described methods and/or shredder  22  and/or shredder blade pair  52  without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but is intended to cover all modifications which are within the spirit and scope of the invention as defined by the above specification, the appended claims and/or shown in the attached drawings.