Abstract:
An improved free swinging hammer mill hammer design is disclosed and described for comminution of materials such as grain and refuse. The hammer design of the present art is adaptable to most hammer mill or grinders having free swinging systems. The improved hammermill hammer may incorporate multiple comminution edges for increased comminution efficiencies. The improved hammermill hammer may incorporate multiple comminution edges for having increased hardness for longer operational run times. The design as disclosed and claimed may be forged to increase the strength of the hammer. The shape of the hammer body may be varied, as disclosed and claimed, to improve the hammer strength reduce or maintain the weight of the hammer while increasing the amount of force delivered to the material to be comminuted. The improved design may also incorporate comminution edges having increased hardness for longer operational run times.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This patent application is a continuation in part of patent application Ser. No. 11/150,430 previously filed on Jun. 11, 2005, now allowed, and applicant herein claims priority from and incorporates herein by reference in its entirety that application. Additionally, applicant claims priority from and incorporates herein by reference in its entirety document number 600,178 filed under the United States Patent &amp; Trademark Office document disclosure program on May 3, 2006. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     No federal funds were used to develop or create the invention disclosed and described in the patent application.  
       REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX  
       [0003]     Not Applicable  
       BACKGROUND OF THE INVENTION  
       [0004]     A number of different industries rely on impact grinders or hammermills to reduce materials to a smaller size. For example, hammermills are often used to process forestry and agricultural products as well as to process minerals, and for recycling materials. Specific examples of materials processed by hammermills include grains, animal food, pet food, food ingredients, mulch and even bark. This invention although not limited to grains, has been specifically developed for use in the grain industry. Whole grain corn essentially must be cracked before it can be processed further. Dependent upon the process, whole corn may be cracked after tempering yet before conditioning. A common way to carry out particle size reduction is to use a hammermill where successive rows of rotating hammer like devices spinning on a common rotor next to one another comminute the grain product. For example, methods for size reduction as applied to grain and animal products are described in Watson, S. A. &amp; P. E. Ramstad, ed. (1987, Corn: Chemistry and Technology, Chapter 11, American Association of Cereal Chemist, Inc., St. Paul, Minn.), the disclosure of which is hereby incorporated by reference in its entirety. The application of the invention as disclosed and herein claimed, however, is not limited to grain products or animal products.  
         [0005]     Hammermills are generally constructed around a rotating shaft that has a plurality of disks provided thereon. A plurality of free-swinging hammers are typically attached to the periphery of each disk using hammer rods extending the length of the rotor. With this structure, a portion of the kinetic energy stored in the rotating disks is transferred to the product to be comminuted through the rotating hammers. The hammers strike the product, driving into a sized screen, in order to reduce the material. Once the comminuted product is reduced to the desired size, the material passes out of the housing of the hammermill for subsequent use and further processing. A hammer mill will break up grain, pallets, paper products, construction materials, and small tree branches. Because the swinging hammers do not use a sharp edge to cut the waste material, the hammer mill is more suited for processing products which may contain metal or stone contamination wherein the product the may be commonly referred to as “dirty”. A hammer mill has the advantage that the rotatable hammers will recoil backwardly if the hammer cannot break the material on impact. One significant problem with hammer mills is the wear of the hammers over a relatively short period of operation in reducing “dirty” products which include materials such as nails, dirt, sand, metal, and the like. As found in the prior art, even though a hammermill is designed to better handle the entry of a “dirty” object, the possibility exists for catastrophic failure of a hammer causing severe damage to the hammermill and requiring immediate maintenance and repairs.  
         [0006]     Hammermills may also be generally referred to as crushers—which typically include a steel housing or chamber containing a plurality of hammers mounted on a rotor and a suitable drive train for rotating the rotor. As the rotor turns, the correspondingly rotating hammers come into engagement with the material to be comminuted or reduced in size. Hammermills typically use screens formed into and circumscribing a portion of the interior surface of the housing. The size of the particulate material is controlled by the size of the screen apertures against which the rotating hammers force the material. Exemplary embodiments of hammermills are disclosed in U.S. Pat. Nos. 5,904,306; 5,842,653; 5,377,919; and 3,627,212.  
         [0007]     The four metrics of strength, capacity, run time and the amount of force delivered are typically considered by users of hammermill hammers to evaluate any hammer to be installed in a hammermill. A hammer to be installed is first evaluated on its strength. Typically, hammermill machines employing hammers of this type are operated twenty-four hours a day, seven days a week. This punishing environment requires strong and resilient material that will not prematurely or unexpectedly deteriorate. Next, the hammer is evaluated for capacity, or more specifically, how the weight of the hammer affects the capacity of the hammermill. The heavier the hammer, the fewer hammers that may be used in the hammermill by the available horsepower. A lighter hammer then increases the number of hammers that may be mounted within the hammermill for the same available horsepower. The more force that can be delivered by the hammer to the material to be comminuted against the screen increases effective comminution (i.e. cracking or breaking down of the material) and thus the efficiency of the entire comminution process is increased. In the prior art, the amount of force delivered is evaluated with respect to the weight of the hammer.  
         [0008]     Finally, the length of run time for the hammer is also considered. The longer the hammer lasts, the longer the machine run time, the larger profits presented by continuous processing of the material in the hammermill through reduced maintenance costs and lower necessary capital inputs. The four metrics are interrelated and typically tradeoffs are necessary to improve performance. For example, to increase the amount of force delivered, the weight of the hammer could be increased. However, because the weight of the hammer increased, the capacity of the unit typically will be decreased because of horsepower limitations. There is a need to improve upon the design of hammermill hammers available in the prior art for optimization of the four (4) metrics listed above.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     The improvement disclosed and described herein centers on an improved hammer to be used in a hammermill. The improved metallic free swinging hammer is for use in rotatable hammer mill assemblies for comminution. The improved hammer is compromised of a first end for securement of the hammer within the hammer mill. The second end of the hammer is opposite the first end and is for contacting material for comminution. This second end typically requires treatment to improve the hardness of the hammer blade or tip.  
         [0010]     Treatment methods such as adding weld material to the end of the hammer blade are well known in the art to improve the comminution properties of the hammer. These methods typically infuse the hammer edge, through welding, with a metallic material resistant to abrasion or wear such as tungsten carbide. See for example U.S. Pat. No. 6,419,173, incorporated herein by reference, describing methods of attaining hardened hammer tips or edges as are well known in the prior art by those practiced in the arts.  
         [0011]     The methods and apparatus disclosed herein may be applied to a single hammer or multiple hammers to be installed in a hammermill. The hammer may be produced through forging, casting or rolling as found in the prior art. Applicant has previously taught that forging the hammer improves the characteristic of hardness for the hammer body. Applicant has also taught the thickness of the hammer edge, in relation to the hammer neck, may also be increased. Re-distributing material (and thus weight) from the hammer neck back to the hammer edge, to increase the moment produced by the hammer upon rotation while allowing the overall weight of the hammer to remain relatively constant. Applicant&#39;s present design may be combined with previous teachings related to the shape of the hammer and the methods of producing the hammer. Thus, the present design may enjoy an increase in actual hammer momentum available for comminution developed and delivered through rotation of the hammer than the hammers as found in the prior art. This increased momentum reduces recoil, as previously disclosed and claimed, thereby increasing operational efficiency. However, because the hammer design is still free swinging, the hammers can still recoil, if necessary, to protect the hammermill from destruction or degradation if a non-destructible foreign object has entered the mill. Thus, effective horsepower requirements are held constant, for similar production levels, while actual strength, force delivery and the area of the screen covered by the hammer face within the hammermill, per each revolution of the hammermill rotor, are improved. The overall capacity of a hammermill employing the various hammers embodied herein is increased over existing hammers.  
         [0012]     As taught, increasing the hammer strength and edge weld hardness creates increases stress on the body of the hammer and the hammer rod hole. In the prior art, the roundness of the rod hole deteriorates leading to elongation of the hammer rod hole. Elongation eventually translates into the entire hammer mill becoming out of balance or the individual hammer breaking at the weakened hammer rod hole area which can cause a catastrophic failure or a loss of performance. When a catastrophic failure occurs, the hammer or rod breaking can result in metallic material entering the committed product requiring disposal. This result can be very expensive to large processors of metal sensitive products i.e. grain processors. Additionally, catastrophic failure of the hammer rod hole can cause the entire hammermill assembly to shift out of balance producing a failure of the main bearings and or severe damage to the hammermill itself.  
         [0013]     Either result can require the hammermill process equipment to be shutdown for maintenance and repairs, thus reducing overall operational efficiency and throughput. During shutdown, the hammers typically must be replaced due to edge wear or rod-hole elongation.  
         [0014]     Another embodiment of this invention illustrates an improved hammermill hammer having an increased number of individual grinding surfaces or edges to improve comminution contact surface area. The hammer design as shown has four (4) individual edges that are offset in vertical height but are nearly equivalent in radial distance from the center point of the rod hole. During use, two (2) of the four (4) contacting edges are used. The hammer shown typically replaces a hammer having only two (2) contacting edges of which only one (1) is used at a time. The width of each contacting edge as shown is equivalent to the width of the hammer. As shown, the edges of the hammer have been welded to increase hardness. The notched portions of the hammer end allow for pocketing and feed of the grain to the contacting edges. It is believed the hammer as shown will increase hammer contact efficiency and therefore overall hammermill efficiency. Although the present art is not so limited, when the present art is produced using forging techniques versus casting or rolling from bar stock the strength of the rod hole is improved and there is a noticeable decrease in the susceptibility of the rod hole to elongation. Furthermore, this embodiment of the present art may be practiced with a hammer body having of uniform shape.  
         [0015]     It is therefore an object of the present invention to disclose and claim a hammer design that is stronger and lighter because it of its thicker and wider securement end but lighter because of its thinner and narrower neck section.  
         [0016]     It another object of the present art to improve the securement end of free swinging hammers for use in hammer mills while still using methods and apparatus found in the prior art for attachment within the hammermill assembly. It is another object of the present invention to improve the operational runtime of hammermill hammers.  
         [0017]     It is another object of the present invention to disclose hammers having hardened edges by such means as welding or heat treating.  
         [0018]     It is another object of the present invention to disclose and claim a hammer allowing for improved projection of momentum to the hammer blade tip to thereby increase the delivery of force to comminution materials.  
         [0019]     It is another object of the present invention to disclose and claim a hammer design that is stronger and lighter because it is forged.  
         [0020]     It is another object of the present invention to disclose and claim an embodiment of the present hammer design that weighs no more than three pounds.  
         [0021]     It is another object of the present invention to disclose and claim a hammer design that allows for improved efficiency by increasing the number of hammer contact edges.  
         [0022]     It is another object of the present invention to disclose and claim a hammer design that allows for improved efficiency by increasing the hammer contact surface area.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     For a better understanding of the present invention, reference is to be made to the accompanying drawings. It is to be understood that the present invention is not limited to the precise arrangement shown in the drawings.  
         [0024]      FIG. 1  provides a perspective view of the internal configuration of a hammer mill at rest as commonly found in the prior art.  
         [0025]      FIG. 2  provides a perspective view of the internal configuration of a hammermill during operation as commonly found in the prior art.  
         [0026]      FIG. 3  provides an exploded perspective view of a hammermill as found in the prior art as shown in  FIG. 1 .  
         [0027]      FIG. 4  provides an enlarged perspective view of the attachment methods and apparatus as found in the prior art and illustrated in  FIG. 3 .  
         [0028]      FIG. 5  provides a perspective view of a first embodiment of the invention.  
         [0029]      FIG. 6  provides an end view of the first embodiment of the invention.  
         [0030]      FIG. 7  provides a side view of the first embodiment of the invention.  
         [0031]      FIG. 8  provides a perspective of second embodiment of the invention.  
         [0032]      FIG. 9  provides an end view of the second embodiment of the invention.  
         [0033]      FIG. 10  provides a side view of the second embodiment of the invention.  
         [0034]      FIG. 11  provides a perspective of third embodiment of the invention.  
         [0035]      FIG. 12  provides a side view of the third embodiment of the invention.  
         [0036]      FIG. 13  provides a top view of the third embodiment of the invention.  
         [0037]      FIG. 14  provides a perspective of fourth embodiment of the invention.  
         [0038]      FIG. 15  provides a side view of the fourth embodiment of the invention.  
         [0039]      FIG. 16  provides a top view of the fourth embodiment of the invention.  
         [0040]      FIG. 17  provides a perspective of fifth embodiment of the invention.  
         [0041]      FIG. 18  provides a side view of the fifth embodiment of the invention.  
         [0042]      FIG. 19  provides a top view of the fifth embodiment of the invention.  
         [0043]      FIG. 20  provides a perspective of the sixth embodiment of the invention.  
         [0044]      FIG. 21  provides an end view of the sixth embodiment of the invention.  
         [0045]      FIG. 22  provides side view of the sixth embodiment of the invention.  
         [0046]      FIG. 23  provides a perspective of the seventh embodiment of the invention.  
         [0047]      FIG. 24  provides an end view of the seventh embodiment of the invention.  
         [0048]      FIG. 25  provides a side view of the seventh embodiment of the invention.  
         [0049]      FIG. 26  provides a top view of the seventh embodiment of the invention.  
         [0050]      FIG. 27  provides a perspective of the eight embodiment of the invention.  
         [0051]      FIG. 28  provides an end view of the eight embodiment of the invention.  
         [0052]      FIG. 29  provides a side view of the eight embodiment of the invention.  
         [0053]      FIG. 30  provides a top view of the eight embodiment of the invention.  
     
    
     DETAILED DESCRIPTION—LISTING OF ELEMENTS  
       [0054]    
       
         
               
               
             
               
               
             
           
               
                   
               
               
                   
               
               
                 Listing of Elements 
                 Element # 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Hammermill assembly 
                 1 
               
               
                 Hammermill drive shaft 
                 2 
               
               
                 End plate 
                 3 
               
               
                 End plate drive shaft hole 
                 4 
               
               
                 End plate hammer rod hole 
                 5 
               
               
                 Center plate 
                 6 
               
               
                 Center plate drive shaft hole 
                 7 
               
               
                 Center plate hammer rod hole 
                 8 
               
               
                 Hammer rods 
                 9 
               
               
                 Spacer 
                 10 
               
               
                 Hammer (swing or free-swinging) 
                 11 
               
               
                 Hammer body 
                 12 
               
               
                 Hammer tip 
                 13 
               
               
                 Hammer rod hole 
                 14 
               
               
                 Hammer center line 
                 15 
               
               
                 Center of rod hole 
                 16 
               
               
                 First end of hammer (securement end) 
                 17 
               
               
                 Thickness of first end of hammer 
                 18 
               
               
                 Radial distance to first and fourth contact points 
                 19 
               
               
                 Hammer neck 
                 20 
               
               
                 Radial distance to second and third contact points 
                 21 
               
               
                 Hammer neck hole 
                 22 
               
               
                 Second end of hammer (contact end) 
                 23 
               
               
                 Thickness of 2nd end of hammer 
                 24 
               
               
                 Hammer hardened contact edge 
                 25 
               
               
                 Linear distance from center line to first and fourth 
                 26 
               
               
                 contact points 
               
               
                 Single stage hammer rod hole shoulder 
                 27 
               
               
                 Second stage hammer rod hole shoulder 
                 28 
               
               
                 Hammer swing length (linear distance from center line 
                 29 
               
               
                 to second and third contact points) 
               
               
                 Hammer Neck edges (hourglass) 
                 30 
               
               
                 Hammer Neck edges (parallel) 
                 31 
               
               
                 1 st  contact surface 
                 32 
               
               
                 2 nd  contact surface 
                 33 
               
               
                 3 rd  contact surface 
                 34 
               
               
                 Secondary contact surface 
                 35 
               
               
                 1 st  contact point 
                 36 
               
               
                 2 nd  contact point 
                 37 
               
               
                 3 rd  contact point 
                 38 
               
               
                 4 th  contact point 
                 39 
               
               
                 Edge pocket 
                 40 
               
               
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION  
       [0055]     The present invention is more particularly described in the following exemplary embodiments that are intended as illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. As used herein, “a,” “an,” or “the” can mean one or more, depending upon the context in which it is used. The preferred embodiments are now described with reference to the figures, in which like reference characters indicate like parts throughout the several views.  
         [0056]     As shown in  FIGS. 1-2 , the hammermills found in the prior art use what are known as free swinging hammers  11  or simply hammers  11 , which are hammers  11  that are pivotally mounted to the rotor assembly and are oriented outwardly from the center of the rotor assembly by centrifugal force.  FIG. 1  shows a hammermill assembly as found in the prior art at rest. The hammers  11  are attached to hammer rods  9  inserted into and through center plates  6 . Swing hammers  11  are often used instead of rigidly connected hammers in case tramp metal, foreign objects, or other non-crushable matter enters the housing with the particulate material to be reduced, such as grain.  
         [0057]     If rigidly attached hammers contact such a non-crushable foreign object within the hammermill assembly housing, the consequences of the resulting contact can be severe. By comparison, swing hammers  11  provide a “forgiveness” factor because they will “lie back” or recoil when striking non-crushable foreign objects.  
         [0058]      FIG. 2  shows the hammermill assembly  1  as in operation. For effective reduction in hammermills using swing hammers  11 , the rotor speed must produce sufficient centrifugal force to hold the hammers in the fully extended position while also having sufficient hold out force to effectively reduce the material being processed. Depending on the type of material being processed, the minimum hammer tips speeds of the hammers are usually 5,000 to 11,000 feet per minute (“FPM”). In comparison, the maximum speeds depend on shaft and bearing design, but usually do not exceed 30,000 FPM. In special high-speed applications, the hammermills can be designed to operate up to 60,000 FPM.  
         [0059]      FIG. 3  illustrates the parts necessary for attachment and securement within the hammermill hammer assembly  1  as shown. Attachment of a plurality of hammers  11  secured in rows substantially parallel to the hammermill drive shaft  2  is illustrated in  FIGS. 3 and 4 . The hammers  11  secure to hammer rods  9  inserted through a plurality of center plates  6  and end plates  3  wherein the plates ( 3 ,  6 ) orient about the hammermill drive shaft  2 . The center plates  6  also contain a number of distally located center plate hammer rod holes  8 . Hammer pins, or rods  9 , align through the holes  3 ,  6  in the end and center plates  3 ,  6  and in the hammers  11 . Additionally, spacers  10  align between the plates. A lock collar  15 , as shown in  FIG. 3 , is placed on the hammer rod  9  to compress and hold the spacers  10  and the hammers  11  in alignment. All these parts require careful and precise alignment relative to each other.  
         [0060]     In the case of disassembly for the purposes of repair and replacement of worn or damaged parts, the wear and tear causes considerable difficulty in realigning and reassembling of the rotor parts. Moreover, the parts of the hammermill hammer assembly  1  are usually keyed to each other, or at least to the drive shaft  2 , this further complicates the assembly and disassembly process. For example, the replacement of a single hammer  11  can require disassembly of the entire hammer assembly  1 . Given the frequency at which wear parts require replacement, replacement and repairs constitute an extremely difficult and time consuming task that considerably reduces the operating time of the size reducing machine. As shown in  FIGS. 3 and 4  for the prior art, removing a single damaged hammer  11  may take in excess of five (5) hours, due to both the rotor design and to the realignment difficulties related to the problems caused by impact of debris with the non-impact surfaces of the rotor assembly.  
         [0061]     Another problem found in the prior art rotor assemblies shown in  FIGS. 1-4  is exposure of a great deal of the surface area of the rotor parts to debris. The plates  3  and  6 , the spacers  10 , and hammers  11  all receive considerable contact with the debris. This not only creates excessive wear, but contributes to realignment difficulties by bending and damaging the various parts caused by residual impact. Thus, after a period of operation, prior art hammermill hammer assemblies become even more difficult to disassemble and reassemble. The problems related to comminution service and maintenance of hammermills provides abundant incentive for improvement of hammermill hammers to lengthen operational run times.  
         [0062]     The hammer  11  embodiments shown in  FIGS. 5-22  are mounted upon the hammermill rotating shaft at the hammer rod hole  14 . As shown, the effective width of hammer rod hole  14  for mounting of the hammer  11  has been increased in comparison to the hammer neck  20  in  FIGS. 5-22 . The hammer neck  20  may be reduced in size because forging the steel used to produce the hammer results in a finer grain structure that is much stronger than casting the hammer from steel or rolling it from bar stock as found in the prior art. As disclosed in the prior art a lock collar  15  secures the hammer rod  9  in place. Another benefit of the present mount of material surface supporting attachment of the hammer  11  to the rod  9  is dramatically increased. This has the added benefit of eliminating or reducing the wear or grooving of the hammer rod  9 . The design shown in the present art at  FIGS. 5-22  increases the surface area available to support the hammer  11  relative to the thickness of the hammer  11 . Increasing the surface area available to support the hammer body  11  while improving securement also increases the amount of material available to absorb or distribute operational stresses while still allowing the benefits of the free swinging hammer design i.e. recoil to non-destructible foreign objects.  
         [0063]      FIGS. 5-7  show a first embodiment of the present invention, particularly hammers to be installed in the hammermill assembly.  FIG. 5  presents a perspective view of this embodiment of the improved hammer  11 . As shown, the first end of the hammer  17  is for securement of the invention within the hammermill assembly  1  (not shown) by insertion of the hammer rod  9  through hammer rod hole  14  of the hammer  11 . In  FIG. 5  the center of the rod hole  16  is highlighted. The distance from the center of rod hole  16  to the contact or second end of the hammer  23  is defined as the hammer swing length  29 . Typically, the hammer swing length  29  of the present embodiment is in the range of eight (8) to ten (10) inches with most applications measuring eight and five thirty seconds inches (8 5/32″) to nine and five thirty seconds (9 5/32″).  
         [0064]     In the embodiment of the hammer  11  shown in  FIGS. 5-7 , the hammer rod hole  14  is surrounded by a single stage hammer rod hole shoulder  27 . In this embodiment, the hammer shoulder  27  is composed of a raised single uniform ring surrounding rod hole  14  which thereby increases the metal thickness around the rod hole  14  as compared to the thickness of the first end of the hammer  18 . The placement of a single stage hammer shoulder  27  around the hammer rod hole  14  of the present art hammer increases the surface area available for distribution of the opposing forces placed on the hammer rod hole  14  in proportion to the width of the hammer thereby decreasing effects leading to rod hole  14  elongation while the hammer  11  is still allowed to swing freely on the hammer rod  9 .  
         [0065]     In this embodiment, the edges of the hammer neck  20  connecting the first end of the hammer  17  to the second end of the hammer  23  are parallel or straight. Furthermore, the thickness of the second end of the hammer  24  and the thickness of the first end of the hammer  18  are substantially equivalent. Because the second end of the hammer  23  is in contact with materials to be comminutated, a hardened contact edge  25  is welded on the periphery of the second end of the hammer  23 .  
         [0066]      FIG. 6  provides an end view of the first embodiment of the invention and further illustrates the thickness of the hammer shoulder  27  in relation the hammer  11  as well as the symmetry of the hammer shoulder  27  in relationship to the thickness of both the first hammer end  17  and second hammer end  23  as shown by hardened welded edge  25 .  FIG. 7  illustrates the flat, straight forged plate nature of the invention, as shown by the parallel edges of the hammer neck  31  from below the hammer shoulder  27  through the hammer neck  20  to second end  23  which provides an improved design through overall hammer weight reduction as compared to the prior art wherein the hammer neck  20  thickness is equal to the hammer rod hole thickness  14 . In the present art, the total thickness of the rod hole  14 , including the hammer shoulder  27 , may be one and half to two and half times greater than the thickness of the hammer neck  20 . In typical applications, the swing length of the present art is in the range of four (4) to eight (8) inches. For example, the forged steel hammer  11  of the first embodiment having a swing length of six (6) inches has a maximum average weight of three (3) pounds. A forged hammer of the prior art with an equivalent swing length having a uniform thickness equal to the thickness of the hammer shoulder  27  would weigh up to four (4) pounds. The present invention therefore improves overall hammermill performance by thirty-three (33%) percent over the prior art through weight reduction without an accompanying reduction in strength. As shown, the hammer requires no new installation procedures or equipment.  
         [0067]     The next embodiment of hammer  11  is shown in  FIGS. 8-10 . As shown, the hammer rod hole  14  is again reinforced and strengthened over the prior art. In this embodiment, the rod hole  14  has been strengthened by increasing the thickness of the entire first end of the hammer  18 . By comparison, the thickness of hammer neck  20  in this embodiment has been reduced, again effectively reducing the weight of the hammer in comparison to the increased metal thickness around the rod hole  14 . This embodiment of the present art hammer also increases the surface area available for distribution of the opposing forces placed on the hammer rod hole  14  in proportion to the thickness of the hammer thereby again decreasing effects leading to rod hole  14  elongation while the hammer  11  is still allowed to swing freely on the hammer rod  9 . The thickness of the second end of the hammer  24  and the thickness of the first end of the hammer  18  are substantially equivalent. Because the second end of the hammer  23  is in contact with materials to be comminutated, a hardened contact edge  25  is welded on the periphery of the second end of the hammer  23 .  
         [0068]      FIG. 8  best illustrates the curved, rounded nature of the second embodiment of the present invention, as shown by the arcuate edges from the first end of the hammer  17  and continuing through hammer neck  20  to the second hammer end  23 . To further reduce hammer weight, hammer neck holes  22  have been placed in the hammer neck  20 . The hammer neck holes  22  may be asymmetrical as shown or symmetrical to balance the hammer  11 . The arcuate, circular or bowed nature of the hammer neck holes  22  as shown allows transmission and dissipation of the stresses produced at the first end of the hammer  17  through and along the neck of the hammer  20 .  
         [0069]     As emphasized and illustrated by  FIGS. 8 and 10 , the reduction in hammer neck thickness and weight allowed through both the combination of the hammer neck shape and hammer neck holes  22  provide improved hammer neck strength at reduced weight therein allowing increased thickness at the first and second ends of the hammer,  17  and  23 , respectively, to improve both the securement of said hammer  11  and also delivered force at the comminution end of the hammer  23 .  
         [0070]     The next embodiment of hammer  11  is shown in  FIGS. 11-13 . The perspective view found at  FIG. 11  provides another embodiment of the present forged hammer which accomplishes the twin objectives of reduced weight and decreased hammer rod hole elongation. The hammer rod hole  14  is again reinforced and strengthened over the prior art in this embodiment which incorporates hammer rod hole reinforcement via two stages labeled  27  and  28 . This design provides increased reinforcement of the hammer rod hole  14  while allowing weight reduction because the rest of the first end of the hammer  18  may be the same thickness as hammer neck  20 . This embodiment of the present art hammer also increases the surface area available for distribution of the opposing forces placed on the hammer rod hole  14  in proportion to the width of the hammer thereby again decreasing effects leading to rod hole  14  elongation while the hammer  11  is still allowed to swing freely on the hammer rod  9 . As shown by  FIG. 13 , the thickness of the second end of the hammer  24  and the thickness of the first end of the hammer  17  are substantially equivalent. Because the second end of the hammer  23  is in contact with materials to be comminutated, a hardened contact edge  25  is welded on the periphery of the second end of the hammer  23 .  
         [0071]      FIG. 11  illustrates the curved hammer neck edges  30  which give the hammer  11  an hourglass shape starting below the hammer rod hole  14  and at the first end of the hammer  17  and continuing through the hammer neck  20  to the second end of the hammer  23 . Incorporation of this shape into the third embodiment of the present invention assists with hammer weight reduction while also reducing the vibration of the hammer  11  as it rotates in the hammer mill and absorbs the shock of contact with comminution materials.  
         [0072]     As shown and illustrated by  FIG. 13  which provides a side view of the present embodiment, the first end of the hammer  17 , the neck  20  and the second end of the hammer  23  are of a substantially similar thickness with the exception of the stage  1  and  2  hammer rod hole reinforcement shoulders,  27  and  28 , to maintain the hammer&#39;s reduced weight over the present art. As emphasized and further illustrated by  FIGS. 11-13 , the reduction in the hammer profile and weight allowed through both the combination of the hammer neck shape  30  and thickness provide improved hammer neck strength at reduced weight therein allowing placement of the stage  1  and  2  hammer rod hole reinforcement shoulders,  27  and  28 , respectively, around the hammer rod hole  14  to improve both the securement of said hammer  11  and performance of the hammermill.  
         [0073]      FIGS. 14-16  illustrate a modification of the present invention as shown in previous  FIGS. 8-10 . In this embodiment the hammer  11  is shown without the hammer neck holes  22  shown in  FIGS. 8-10 . This embodiment of the present invention, without hammer neck holes  22 , provides an improvement over the present art by combining a thickened or thicker hammer rod hole  14  by increasing the thickness of the first or securement end of the hammer  17  in relation to the hammer neck  20  and second end of the hammer  23 . This modification of the embodiment is lighter and stronger than the prior art hammers.  
         [0074]      FIGS. 17-19  present another embodiment of the present art wherein the first end of the hammer  17 , the hammer neck  20  and the second end of the hammer  23  are substantially of similar thickness i.e. the dimensions represented by  18  and  24  are substantially equivalent. In this embodiment, the hammer rod hole  14  has been strengthened through placement of a single reinforcing hammer shoulder  27  around the perimeter of the hammer rod hole  14 , on both sides or faces of the hammer  11 . The rounded shape of the first end of the hammer  17  strengthens the first end of the hammer  17  by improving the transmission of any hammer rod  9  vibration away from the securement end of the hammer  17  through the hammer neck  20  to the second end of the hammer  23 . The round shape also allows further weight reduction. In this embodiment, the hammer neck edges  31  are parallel as are the hammer neck edges in  FIGS. 5-7 . A hardened contact edge  25  is shown welded on the periphery of the second end of the hammer  23 .  
         [0075]      FIGS. 20-22  present another embodiment of the present art wherein the first end of the hammer  17 , the hammer neck  20  and the second end of the hammer  23  are substantially of similar thickness i.e. the dimensions represented by  18  and  24  are substantially equivalent. In this embodiment, the hammer rod hole  14  has been strengthened through placement of a single reinforcing stage  27  around the perimeter of the hammer rod hole  14 , on both side or faces of the hammer  11 . A hardened contact edge  25  is shown welded on the periphery of the second end of the hammer  23 . In this particular embodiment, the hammer neck edges  30  have been rounded to further improve vibration energy transfer to the second end of the hammer  23  and away from the securement end of the hammer  17 .  
         [0076]      FIGS. 23-30  illustrate two additional embodiments of the present art. As shown, the hammers  11  illustrated in  FIGS. 23-30  present an increased number of individual contact surfaces to improve available comminution contact surface area. This improvement may be embodied in hammers  11  produced using either casting or forging techniques. Additionally, the body of the hammer  12  may be improved by heat treatment methods known to those practiced in the arts for improved wear characteristics.  
         [0077]     Typically, the hammer  11  embodiments shown in  FIGS. 23-26  are mounted upon the hammermill rotating shaft at the hammer rod hole  14 . As disclosed in the prior art a lock collar  15  secures the hammer rod  9  in place. As shown in  FIGS. 23-26 , the thickness of the neck connecting said the first hammer end to the second hammer end has not been reduced in relation to first and second hammer ends. During typical use of the present embodiment, two of the three contacting surfaces edges are used. As those practiced in the arts will understand, the metallic based hammer as disclosed may be used bi-directionally by either reversing the direction of rotation of the hammermill assembly or in a fixed direction of rotation hammermill assembly, the hammer may be re-installed in the hammermill assembly in a reverse orientation to allow a reversal of the contact surfaces as described further herein.  
         [0078]     The second end of the hammer  23  has three distinct contact surfaces ( 32 ,  33 ,  34 ) respectively. The hammer  11  as shown is symmetrical along the length of the hammer neck  20  so that during normal operation in a first direction of rotation, the edges of the first and second contact surfaces,  32  and  33 , respectively, will be the leading surfaces. The third contact surface will be a trailing edge and will wear very little. The first contact point  36  and the second contact point  37  will be the leading contact points. The third contact point  38  and the fourth contact points  39  will be the trailing contact points and will wear very little.  
         [0079]     If the direction of rotation of the hammer  11  is reversed, either by reversing the direction of rotation of the hammermill assembly  1  or re-installing the hammer  11  in the opposite orientation, the third contact surface  34  and the second contact surface  33  will be the leading surfaces. The third contact point  38  and the fourth contact point  39  will be the leading contact points. The first contact point  36  and the second contact point  37  will then be in the trailing position.  
         [0080]     As shown, the combined width of the contacting surfaces ( 32 ,  33  and  34 ) is substantially equivalent to the width of the second end of the hammer  11 . In the embodiments shown, the edges of the hammer  11  have been welded to increase hardness. Tungsten carbide has been applied by welding to the periphery of the second end for increased hardness. Other types of welds as well known to those practiced in the arts may also be applied.  
         [0081]     As best shown in  FIG. 26 , the distance to the second contact surface  33  from the rod hole centerline  15  is not equal to the distance from rod hole centerline  15  to the first and third contact surfaces,  32  and  34 , respectively. The three contact surfaces ( 32 ,  33  and  34 ) have first  36 , second  37 , third contact  38  and fourth contact  39  points for contact and delivery of momentum to the material to be comminuted. The radial distance from the center of the rod hole  16  to the first  36 , second  37 , third  38  and fourth  39  contact points are equal. This spatial relationship is best illustrated in  FIG. 23  and  FIG. 27 . The radial distance from the center of the rod hole  16  to the first and fourth contact points,  36  and  39 , respectively, is labeled  19 . The radial distance from the center of the rod hole  16  to the second and third contact points,  37  and  38 , respectively, are labeled  21 .  
         [0082]      FIGS. 27-30  illustrate another version of the present art wherein an edge pocket  40  has been placed at the second end of the hammer  23 . The edge pocket(s)  40  are notched portion(s) placed fore and aft of the second contact surface  33  to allow temporary insertion or “pocketing” of the comminution materials during rotation of the hammermill assembly  1  to increase loading upon the contacting surfaces and thereby increase hammer contact efficiency and overall hammermill efficiency. The depth of the hammer edge pocket is proportional to the difference between the hammer swing length  29  and the distance from the rod hole center line  15  to the first or third contact surfaces,  32  and  34 , respectively. The depth of the hammer edge pocket is in the range of 0.25 to 2 times the thickness of the hammer. The geometry of the edge pocket  39  may be rounded or sloped (not shown).  
         [0083]     In the embodiment shown in  FIGS. 27-30  the effective width of hammer rod hole  14  for mounting of the hammer  11  has been increased in comparison to the hammer neck  20  in  FIG. 14 . The hammer neck  20  may be reduced in size because forging the steel used to produce the hammer results in a finer grain structure that is much stronger than casting the hammer from steel or rolling it from bar stock as found in the prior art. As disclosed in the prior art a lock collar  15  secures the hammer rod  9  in place. Another benefit of the present art is the amount of material surface supporting attachment of the hammer  11  to the rod  9  is dramatically increased. This has the added benefit of eliminating or reducing the wear or grooving of the hammer rod  9 . The design shown in the present art at  FIGS. 27-30  increases the surface area available to support the hammer  11  relative to the thickness of the hammer  11 . Increasing the surface area available to support the hammer body  11  while improving securement also increases the amount of material available to absorb or distribute operational stresses while still allowing the benefits of the free swinging hammer design i.e. recoil to non-destructible foreign objects.  
         [0084]     Those practiced in the arts will understand that the advantages provided by the hammer design disclosed may produced by other means not disclosed herein but still falling within the present art taught by applicant.