Abstract:
The various embodiments disclosed and pictured illustrate a curved hammer for comminuting various materials. The illustrative embodiments pictured and described herein are primarily for use with a rotatable hammermill assembly. The curved hammer includes a connection portion having a rod hole therein, a contact portion for delivery of energy to the material to be comminuted, and a curved neck portion affixing the connection portion to the contact portion. In other embodiments, a shoulder is positioned around the periphery of the rod hole for added strength. In still other embodiments, a neck reinforcement is positioned along a portion of the neck for increased strength. A weld or plurality of welds may be affixed to various surfaces of the contact portion to aide in comminuting and/or longevity of the curved hammer.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present non-provisional patent application claims priority from and is a continuation of U.S. patent application Ser. No. 13/146,612 filed on Feb. 23, 2012, which application was a continuation of and claimed priority from U.S. patent application Ser. No. 12/786,202 filed on May 24, 2010, which application claimed priority from provisional U.S. Pat. App. No. 61/180,773 filed on May 22, 2009, all of which are incorporated by reference herein in their entireties. 
    
    
     FIELD OF INVENTION 
     This invention relates generally to a device for comminuting or grinding material. More specifically, the invention is especially useful for use as a hammer in a rotatable hammermill assembly. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     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 
     Not Applicable 
     BACKGROUND 
     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. 
     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. 
     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. 
     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. 
     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. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a hammer for use in a rotatable hammermill assembly wherein the primary contact surface of the hammer remains normal to the screen of the hammermill assembly during rotation. 
     It is another object of the present invention to provide a hammer having a primary contact surface of greater area than the respective area of similar hammers. 
     Other objects and advantages of the present invention will, in part, be apparent from the specification when considered in conjunction with the drawings and claims hereof. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limited of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings. 
         FIG. 1  provides a perspective view of a first embodiment of the curved hammer. 
         FIG. 2  provides a top view of the first embodiment of the curved hammer. 
         FIG. 2A  provides a side view of the first embodiment of the curved hammer. 
         FIG. 3  provides a perspective view of a second embodiment of the curved hammer. 
         FIG. 4  provides a side view of the second embodiment of the curved hammer having a plurality of welds on the primary contact surface. 
         FIG. 5  provides a perspective view of a third embodiment of the curved hammer. 
         FIG. 6  provides a top view of the third embodiment of the curved hammer. 
     
    
    
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 DETAILED DESCRIPTION - LISTING OF ELEMENTS 
               
             
          
           
               
                   
                 Element 
                 Element # 
               
               
                   
                   
               
               
                   
                 Curved hammer 
                 10 
               
               
                   
                 Rod hole 
                 12 
               
               
                   
                 Connection portion 
                 13 
               
               
                   
                 Shoulder 
                 14 
               
               
                   
                 Neck 
                 16 
               
               
                   
                 Neck first end 
                  17a 
               
               
                   
                 Neck second end 
                  17b 
               
               
                   
                 Neck reinforcement 
                 18 
               
               
                   
                 Neck bottom surface 
                  19a 
               
               
                   
                 Neck top surface 
                  19b 
               
               
                   
                 Contact portion 
                 20 
               
               
                   
                 Primary contact surface 
                 22 
               
               
                   
                 Weld 
                 24 
               
               
                   
                 Side contact surface 
                 26 
               
               
                   
                 Bottom contact surface 
                 28 
               
               
                   
                 Split connection portion 
                 50 
               
               
                   
                 First arm 
                 52 
               
               
                   
                 Second arm 
                 54 
               
               
                   
                 Void 
                 55 
               
               
                   
                 Tapered shoulder 
                 56 
               
               
                   
                   
               
             
          
         
       
     
     DETAILED DESCRIPTION 
     Illustrative Embodiments 
     Before the various embodiments of the present invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that phraseology and terminology used herein with reference to device or element orientation (such as, for example, terms like “front”, “back”, “up”, “down”, “top”, “bottom”, and the like) are only used to simplify description of the present invention, and do not alone indicate or imply that the device or element referred to must have a particular orientation. In addition, terms such as “first”, “second”, and “third” are used herein and in the appended claims for purposes of description and are not intended to indicate or imply relative importance or significance. Furthermore, any dimensions recited or called out herein are for exemplary purposes only and are not meant to limit the scope of the invention in any way unless so recited in the claims. 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views,  FIG. 1  provides a perspective view of a first embodiment of the curved hammer  10  and  FIG. 2  provides a top view thereof. As shown herein, the neck first end  17   a  of the neck  16  is affixed to a connection portion  13  of the curved hammer  10 . The connection portion  13  in the first embodiment of the curved hammer  10  is formed with a rod hole  12  through the center of the connection portion  13 . As is well known to those skilled in the art, the rod hole  12  is most often used to pivotally join the curved hammer  10  to a hammer pin or rod (neither shown), which hammer pins or rods often extend through plates (not shown) of a hammer mill assembly. These elements and their operation are not further described herein for purposes of clarity, but the patents incorporated by reference herein in the background provide more detail on such hammer mill assemblies. 
     In the first embodiment, the connection portion  13  is rounded, as best shown in  FIG. 1 . In the first embodiment, the outer diameter of the connection portion  13  is two and one-half inches. However, in other embodiments not pictured herein, the connection portion  13  may have other shapes, such as rectangular, triangular, elliptical, or otherwise without departing from the spirit and scope of the curved hammer  10 . Furthermore, the relative dimensions and angles of the various elements of the curved hammer  10  may be adjusted for the specific application of the curved hammer  10 , and therefore an infinite number of variations of the curved hammer  10  exist, and such variations will naturally occur to those skilled in the art without departing from the spirit and scope of the curved hammer  10 . 
     A shoulder  14  may be positioned on the connection portion  13  surrounding the rod hole  12 , as shown in the various embodiments pictured herein. The shoulder  14  provides increased strength and longevity to the curved hammer  10  in many applications, as is well known to those skilled in the art. In the various embodiments pictured herein, the shoulder  14  is positioned on both sides of the rod hole  12 . However, in other embodiments not pictured herein, the shoulder  14  is positioned on only one side of the rod hole  12 . The optimal dimensions of the shoulder  14  will vary depending on the specific application of the curved hammer  10 , and are therefore in no way limiting to the scope of the curved hammer  10 . In the first embodiment, the thickness of the shoulder  14  is 0.75 inches. 
     As best shown in  FIG. 1 , the neck  16  of the curved hammer  10  is non-linear. As shown in the first embodiment herein, the neck bottom surface  19   a  is derived from a circle having a radius of four and one-half inches, and the neck top surface  19   b  is derived from a circle having a radius of seven inches. As is apparent from  FIG. 1 , the circles from which the neck bottom surface  19   a  and neck top surface  19   b  are derived have offset center points (not shown). That is, the circle from which the neck bottom surface  19   a  is derived is positioned to toward the contact portion  20  with respect to the circle from which the neck top surface  19   b  is derived. Accordingly, as one progresses from the neck first end  17   a  to the neck second end  17   b , the distance between the neck bottom surface  19   a  and neck top surface  19   b  decreases. In the first embodiment the center of the rod hole  12  is one inch below the neck bottom surface  19   a , and the length of the curved hammer  10  from the center of the rod hole  12  to the primary contact surface  22  of the contact portion  20  is eight and one-quarter inches. The width of the neck  16  in the first embodiment is 0.375 inches. However, in other embodiments, whether pictured herein or otherwise, the overall length of the curved hammer  10  may be greater or less than that of the first embodiment depending on the configuration of the hammermill assembly (not shown) for which the curved hammer  10  is designed. Furthermore, the optimal width for the neck  16  will vary depending on the specific application of the curved hammer  10 , which may depend on the type of material to be comminuted. 
     The neck  16  may also include a neck reinforcement  18 , as shown in the various embodiments pictured herein. The neck reinforcement  18  serves to make the neck  16 , and subsequently the entire curved hammer  10 , more robust and increase the longevity thereof. In the first embodiment of the curved hammer  10  the thickness of the neck reinforcement  18  is 0.75 inches, which is equal to the thickness of the shoulder  14  in the first embodiment. However, the optimal dimensions of the neck reinforcement  18  will vary depending on the specific application of the curved hammer  10 , and the thickness thereof need not necessarily be the same as the thickness of the shoulder  14 . Accordingly, in embodiments not pictured herein, the thickness of the neck reinforcement  18  is greater than the thickness of the shoulder  14 , and in other embodiments not pictured herein the thickness of the neck reinforcement  18  is less than the thickness of the shoulder  14 . Furthermore, the distance the neck reinforcement  18  extends from the shoulder  14  towards the neck second end  17   b  and the width of the neck reinforcement  18  may be varied in an infinite number of configurations within the spirit and scope of the curved hammer  10 . The neck reinforcement  18  may be included on both sides of the neck  16 . However, in other embodiments not pictured herein, the neck reinforcement  18  may be included on only one side of the neck  16 . 
     The neck second end  17   b  is affixed to the contact portion  20 . The contact portion  20 , which delivers energy to the material to be comminuted, includes a primary contact surface  22 . The primary contact surface  22  is generally the face of the contact portion  20  that is adjacent the screen (not shown) during operation of a hammermill assembly. In the first embodiment the widest portion of the primary contact surface  22  is 1.5 inches. As shown in the various embodiments pictured herein, the surface area of the primary contact surface  22  of the curved hammer  10  is greater than that of prior art hammers. The increased surface area of the primary contact surface  22  increases the amount of work done by the curved hammer  10  per strike as compared to those of the prior art. 
     In the first embodiment the primary contact surface  22  forms an irregular hexagon, which is best shown in  FIG. 1 . However, the specific shape of the primary contact surface  22  is in no way limiting. For example, in the second embodiment of the curved hammer  10  as shown in  FIGS. 3 and 4 , the primary contact surface  22  is rectangular in shape. Accordingly, the primary contact surface  22  may have any shape suitable for the specific application of the curved hammer  10 . Another difference between the first and second embodiments is the shape of the side contact surface  26 . A comparison of the side views of the first and second embodiments (shown in  FIGS. 2A and 4 , respectively) shows that the contact portion  20  in the first embodiment is different from that in the second embodiment. In the first embodiment, the side contact surface  26  (as shown in  FIG. 2A ) is primarily rectangular in shape, with the bottom contact surface  28  having the same width as the side contact surface  26 . However, in the second embodiment, the side contact surface  26  (as shown in  FIG. 4 ) is primarily pentagonal in shape, with a narrower bottom contact surface  28  as compared to the bottom contact surface  28  of the first embodiment. 
     In the second embodiment, the curvature of the neck bottom surface  19   a  continues through the contact portion  20  and terminates at the bottom contact surface  28 . The surface of the contact portion  20  through which the neck bottom surface  19   a  extends may have the same curvature as that of the neck bottom surface  19   a , as shown in  FIG. 4 . However, in other embodiments, different orientations, angles, or dimensions of the contact portion  20 , primary contact surface  22 , side contact surface  26 , and bottom contact surface  28 , may be present without departing from the spirit and scope of the curved hammer  10 . 
     In the second embodiment of the curved hammer  10 , a plurality of welds  24  is affixed to the primary contact surface  22 . These welds  24  may be of a hardened material to increase the efficacy and longevity of the curved hammer  10 . The materials used to create a weld  24  will vary depending on the specific application of the curved hammer  10 , which includes consideration for the material to be comminuted, and variations will become apparent to those skilled in the art in light of the present disclosure. For example, a weld  24  may be constructed of steel, an iron alloy, an aluminum alloy, a tungsten alloy, another metallic alloy, or any combination thereof known to those skilled in the art. Additionally, welds  24  may be positioned on other surfaces of the contact portion  20 , such as the bottom contact surface  28  and/or side contact surface  26 . 
     A third embodiment of the curved hammer  10  is shown in  FIGS. 5 and 6 . The third embodiment employs a contact portion  20  substantially the same as that of the second embodiment save for the welds  24  placed on the primary contact surface  22  in the second embodiment. The third embodiment employs a split connection portion  50  through which the rod hole  12  is positioned. The split connection portion  50  is comprised of a first arm  52  and a second arm  54  with a void  55  positioned therebetween. The first and second arms  52 ,  54  may be generally symmetrical with respect to the void  55  as shown in  FIG. 6 . The void  55  extends approximately half the diameter of the rod hole  12  such that the portion of the rod (not shown) adjacent the void  55  when the curved hammer  10  is engaged with a hammermill assembly is unobstructed by the curved hammer  10 . This void  55  adjacent the rod allows grain to migrate away from the rod during use. 
     The third embodiment includes a tapered shoulder  56  positioned on the first arm  52  and a tapered shoulder  56  positioned on the second arm  54 , wherein both tapered shoulders  56  are positioned opposite the void  55  and the respective arms  52 ,  54 . In the third embodiment, the total width of the split connection portion  50  (the distance from the exterior surface of the first arm  52  to the exterior surface of the second arm  54 ) is approximately equal to the width of the contact portion  20 . However, the configuration, specific dimensions, and angles of the connection portion  13  and tapered shoulder  56  may vary from one embodiment of the curved hammer  10  to the next, and therefore are in no way limiting to the scope thereof. 
     The precise distance the void  55  extends through the rod hole  12  may be different in different embodiments not pictured herein, and is therefore in no way limiting to the scope of the curved hammer  10 . Furthermore, the precise width of the void  55  (i.e., the distance between the interior surfaces of the first and second arms  52 ,  54 ) may be different from one embodiment to the next. In embodiments of the curved hammer  10  not pictured herein, the first and second arms  52 ,  54  may extend past the rod hole  12  in the direction opposite the neck second end  17   b  by an amount greater than that shown for the third embodiment pictured herein. 
     The curved hammer  10  may be installed in a hammermill assembly to rotate in any direction. However, it is contemplated that from the vantage shown in  FIGS. 2A and 4 , the curved hammer  10  will rotate in a counterclockwise direction. Accordingly, with most embodiments of a hammermill assembly in the prior art, the curved hammer  10  allows the primary contact surface  22  to remain substantially normal to the screen (not shown) of the hammermill assembly, which increases the efficiency of the comminution of the material. The curved hammer  10  is more efficient because when the primary contact surface  22  remains substantially normal to the screen, the entire surface area of the primary contact surface  22  may work to comminute material. 
     The materials used to construct the connection portion  13 , shoulder  14 , neck  16 , neck reinforcement  18 , and contact portion  20  will vary depending on the specific application for the curved hammer  10 . Certain applications will require a high tensile strength material, such as steel, while others may require different materials, such as carbide-containing alloys. Accordingly, the above-referenced elements may be constructed of any material known to those skilled in the art, which material is appropriate for the specific application of the curved hammer  10 , without departing from the spirit and scope of the curved hammer as disclosed and claimed herein. 
     Other methods of using the curved hammer  10  and embodiments thereof will become apparent to those skilled in the art in light of the present disclosure. Accordingly, the methods and embodiments pictured and described herein are for illustrative purposes only. The curved hammer  10  also may be used in other manners, and therefore the specific hammermill in which the curved hammer  10  is used in no way limits the scope of the curved hammer. 
     It should be noted that the curved hammer  10  is not limited to the specific embodiments pictured and described herein, but is intended to apply to all similar curved hammers  10 . Modifications and alterations from the described embodiments will occur to those skilled in the art without departure from the spirit and scope of the curved hammer  10 .