Abstract:
The present invention relates generally to a method of manufacturing broadhead components utilizing a powder injection molding (PIM) process that reduces the number of operations, thus simplifying the manufacturing process required to produce a finished product while maintaining the precision essential to the function of this commodity. The method of manufacturing includes powder injection molding one or more than one components for a broadhead, sintering the component(s) at an elevated temperature to form component(s) and assembling the component(s) to form a broadhead.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of prior application Ser. No. 09/910,385 entitled “Broadhead and Method of Manufacture” filed on Jul. 20, 2001 now U.S. Pat. No. 6,595,881, which is a continuation in part of prior application Ser. No. 09/546,146 entitled “Broadhead and Method of Manufacture” filed on Apr. 10, 2000 now U.S. Pat. No. 6,290,903 and which also claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 60/219,474 filed on Jul. 20, 2000 and entitled Expanding Archery Broadhead, the specification and drawings of which are hereby expressly incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to an archery arrow and more specifically to the design and method of manufacture of the broadhead for an archery arrow. 
     The components of a typical archery broadhead include a ferrule or body having one or more blades extending therefrom. Additionally, the tip of the broadhead may be a separate component secured to the front of the ferrule. Two types of archery broadheads are generally known in the industry as fixed or replaceable blade broadheads and moveable or mechanical blade broadheads. The moveable blade broadheads, by design, are in a closed position in flight and open upon impact with the target. 
     Conventionally, the components of archery broadheads are manufactured using a variety of processes. The ferrule is conventionally turned or stamped with a male thread at the end where it attaches to an arrow shaft. Where the tip is not formed is  as an integral of the ferrule, an internal or female thread is formed on the front of the ferrule for receiving and securing the broadhead tip. Additional machining operations are necessary to provide the slots or other openings in the ferrule essential to the attachment of the blades. The blades are generally stamped steel with a uniform cross-section that requires subsequent grinding and honing operations to provide the sharpened edges. Thus, removable blades adds  add to the complexity of manufacturer  manufacturing, as does the use of irregular skin surface treatments on the ferrule. Tapered blades instead of stamped blades add strength and resistance to bending. 
     Broadhead components manufactured using conventional processes require a variety of costly equipment to achieve and maintain the precision essential to proper functioning of this commodity. Accordingly, there is a need to provide an efficient method of manufacturing from  of many of the broadhead components to reduce the cost, add design flexibility and still maintain the precision required. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a method of manufacturing broadhead components utilizing a process that reduces the number of operations, and thus simplifies the process,  required to produce a finished product while maintaining the precision essential to the function of this commodity. 
     It is an additional object of the present invention to provide different materials as dictated by the particular application, in the manufacture of broadhead components utilizing the aforementioned process. 
     It is another object of the present invention to provide a monolithic ferrule, manufactured utilizing a powder injection molding (PIM) process incorporating integral design features necessary for the proper assembly and functioning of the broadhead. 
     It is a further object of the present invention to provide broadhead blades, manufactured by the PIM process, with tapered or otherwise varying cross sections so as to enhance the strength in  and aerodynamic qualities of the broadhead. 
     It is yet another object of the present invention to provide blades, manufactured by the PIM process, having scalloped, serrated or otherwise varying cutting edge treatments so as to enhance the cutting and penetration abilities of the broadhead. 
     It is an additional object of the present invention to provide a broadhead point, manufactured by the PIM process which may be used interchangeably with a variety of ferrules. 
     It is still another object of the present invention to provide a ferrule and broadhead point, either separately or integral with the ferrule, manufactured by the PIM process having a surface texture so as to enhance the aerodynamic and penetration qualities of the broadhead. 
     In accordance with a first preferred embodiment of the present invention, an expanding-blade broadhead is provided including a ferrule having an integral boss formed thereon, a plurality of cutting blades supported on the boss and pivotally coupled to the ferrule and a collar for retaining the blades on the boss while permitting free rotation thereof. A threaded shank portion is formed on the end of the ferrule opposite the point for securing the broadhead to the arrow shaft in a conventional manner. The use of powdered metallurgy and subsequent sintering processes provides a preferred, but not essential method of manufacturing the ferrule and retaining collar. 
     In accordance with a second preferred embodiment of the present invention, a fixed blade broadhead is provided including a ferrule having a blade receiving slot formed therein, a broadhead tip threadedly secured to the ferrule and a plurality of cutting blades disposed in the slots formed in the ferrule and releasably secured thereto by the broadhead tip. A threaded shank portion is formed on the end of the ferrule opposite the point for securing the broadhead to an arrow shaft in a conventional manner. The use of powdered metallurgy and subsequent sintering processes provides a preferred, but not essential method of manufacturing the ferrule, blades and broadhead tip. 
    
    
     
       These and other objects, features and advantages of the present invention will become apparent from the following description when viewed in accordance with the accompanying drawings and appended claims. 
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an expanding-blade broadhead in accordance with the present invention in which the blades are in a retracted position and with an arrow shaft illustrated in phantom lines; 
         FIG. 2  is a cross-section taken through lines II—II shown in  FIG. 1 ; 
         FIG. 3  is a detailed perspective view illustrating the ferrule and retaining collar of the present invention; 
         FIG. 4  is a cross-sectional view of a portion of the ferrule and the retaining collar shown in  FIG. 3 ; 
         FIG. 5  is an exploded side view illustrating the components of the expanding-blade broadhead of the present invention; 
         FIG. 6  is a partial cross-section illustrating the pivotal connections between the ferrule and the cutting blade; 
         FIG. 7  is a side view of the expanding-blade broadhead shown in a retracted position; 
         FIG. 8  is a side view of the expanding-blade broadhead shown in the deployed position; 
         FIG. 9  is an exploded side view of a fixed-blade broadhead in accordance with the present invention with an arrow shaft illustrated in phantom lines; 
         FIG. 10  is a cross-sectional view taken through the ferrule portion of the broadhead illustrated in  FIG. 9 ; 
         FIG. 11  is an alternate embodiment of a ferrule for the fixed-blade broadhead having a surface texture treatment; 
         FIG. 12  is a cross-sectional view taken through the ferrule portion of the broadhead illustrated in  FIG. 11 ; 
         FIG. 13  is a detailed cross-section view taken through the blade portion of the broadhead illustrated in  FIG. 9  showing tapered blade possibilities; 
         FIG. 14  is an alternate embodiment of the blade for the fixed blade broadhead assembly illustrated in  FIG. 9 ; 
         FIG. 15  is a schematic diagram generally illustrating the method of manufacturing components of the broadhead in accordance with the present invention using powdered metallurgy technology; and 
         FIG. 16  is a flow chart illustrating the method of manufacturing the components of the broadhead in accordance with the present invention using powdered metallurgy technology. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference now to the  FIGS. 1-8 , a first preferred embodiment of the present invention is illustrated in the form of an expandable-blade broadhead. Broadhead  10  includes ferrule  12 , cutting blades  14  pivotally coupled to ferrule  12  and collar  16  disposed over an end of ferrule  12  for retaining cutting blades  14  thereon. 
     A substantially conical or trocar shaped tip  18  is formed at a forward end of ferrule  12 . The body  20  of ferrule  12  is generally conical or trocar shaped having a triangular cross-section as best seen in FIG.  2 . Each of the vertices  22  of body  20  has a slot  24  formed therein which receives cutting blade  14  when in the retracted position. Ferrule  12  further has a base portion  26  having three lugs  28  extending radially from the ferrule. A boss  30  extends from the radial face  32  of lug  28 . Shank  34  extends rearwardly from base portion  26  and has a male threaded portion  36  formed at the end thereof for operably coupling broadhead  12  to arrow shaft  38 . 
     Cutting blades  14  have a cutting edge  40  formed thereon. Aperture  42  is formed in a bottom portion of cutting blade  14  and is adapted to received  receive boss  30  for pivotally coupling cutting blade  14  to ferrule  12 . Collar  16  is slidably received over shank  34  and has an annular skirt portion  44  with fingers  46  extending longitudinally forward such that fingers  46  are positioned adjacent to lugs  28  formed on ferrule  12 . A radial face  48  defined by fingers  46  is generally parallel to but spaced apart from radial face  32  to further define slot  24 . As best seen in  FIG. 6  a slight clearance is provided between the end of boss  30  and the radial face  48  of finger  46  such that collar  16  may be readily positioned onto ferrule  12 , while at the same time sufficiently retaining cutting blade  14  onto boss  30 . 
     As best seen in  FIG. 5 , broadhead  10  is threadedly secured to arrow shaft  38  such that the forward face  50  of arrow shaft  38  pushes retaining collar  16  onto ferrule  12 . As presently preferred, a compliant element  52  is interdisposed between rearward face  54  formed on retaining collar  16  and forward face  50  of arrow shaft  38  to prevent loosening therebetween. 
     While various design features have been described above, one skilled in the art will readily recognize that certain modifications, variations and changes may be made without departing from the scope of the invention. In this regard the overall shape and geometric configuration of the ferrule may be adapted to various shapes. In addition, the expanding broadhead may incorporate more or less cutting blades as the particular application requires. The retaining collar may be secured to the ferrule by other suitable manners. The shaft of the ferrule may be formed of a separate piece from the body of the ferrule. 
     As previously indicated, some of the components of broadhead  10 , and in particular ferrule  12  and retaining collar  16  may be manufactured using a powdered metallurgical manufacturing process resulting in monolithic components. The powdered metallurgical process permits net shape or near net shape parts which have intricate design features. Furthermore, the powdered metallurgical process provides greater control over the shape and weight of the broadhead, and also improves the overall strength of the broadhead. The powdered metallurgical process also eliminates many fabricating and machining steps associated with conventional broadhead manufacturing. 
     With references now to  FIGS. 9-14 , a second preferred embodiment of the present invention is illustrated in the form of a fixed-blade broadhead. Broadhead  110  includes ferrule  112 , and cutting blades  114  releasably secured to ferrule  112 . A conical or trocar shaped tip  118  is threadedly secured at a forward end of ferrule  112  and functions to releasably secure cutting blades  114  thereon. The body  120  of ferrule  112  is generally conically shaped having a triangular cross-section as best seen in FIG.  10  and has a shank  134  extending rearwardly therefrom. Each of the vertices  122  of body  120  has a T-shaped slot  124  formed therein which releasably secures cutting blades  114  to ferrule  112 . 
     Cutting blades  114  have a cutting edge  140  formed along the distal edge thereof. As best seen in  FIG. 13 , a bead  142  having a profile which compliments T-shaped slot  124  is formed along the proximal edge of cutting blade  114 . A generally triangular aperture  144  is formed in the body of cutting blade  114  to reduce the overall weight of the broadhead and distribute the mass of the blade around its perimeter. As presently preferred, cutting blade  114  has a tapering cross-section from the proximal edge  146  to the distal cutting edge  140 . 
     Slot  124  is configured to receive the proximal edge  146  of cutting blade  114  including bead  142 . Cutting blade  114  is slid axially into slots  124  formed in ferrule  112 . A threaded shank  148  is formed on the back surface of broad tip point  118  and is received in a threaded aperture  152  formed in ferrule  112 . In this way, broadhead tip  118  retains and secures cutting blades  114  with ferrule  112 . While a T-shaped slot configuration and complimentary bead profile is presently preferred, one skilled in the art will recognize that other slot configurations and bead profiles (such as L-shaped, circular, square, etc.) which cooperate to releasably secure blades  114  to ferrule  112  are contemplated by the present invention. 
     Broadhead  110  may be threadedly secured to arrow shaft  154  in the manner heretofore described. A compliant element (not shown) may be interdisposed between ferrule  112  and arrow shaft  154  to prevent loosening therebetween. As presently preferred, blades  114  are releasably secured to ferrule  112  by tip  118 . However, one skilled in the art will recognize that ferrule  112  could be configured such that a retaining element disposed over shank  134  or arrow shaft  154  functions to releasably secure blades  114  to ferrule  112 . 
     With reference now to  FIG. 11 , an alternate embodiment of the ferrule is illustrated. The body  120 ′ of ferrule  112 ′ is generally pyramidally shaped having a triangular cross-section as best seen in FIG.  12 . Each of the vertices  122 ′ of body  120 ′ has a slot  124 ′ formed therein which receives cutting blades  114 . The planar surfaces  121 ′ of body  120 ′ have a generally textured surface formed thereon for enhancing aerodynamic and penetration properties of the broadhead. In this regard, U.S. Pat. No. 5,871,410, the disclosure of which is expressly incorporated by reference herein, discloses a broadhead in which the ferrule has such a textured surface. 
     With reference now to  FIG. 14 , an alternate embodiment of the cutting blades utilized in the present invention is illustrated. Specifically, cutting blade  114 ′ is generally triangularly configured having a cutting edge  140 ′ formed on a distal edge thereof. In addition, a plurality of scallops or serrations  141 ′ are formed in the cutting edge to further facilitate cutting of the broadhead upon impact. Cutting blade  114 ′ further includes a bead disposed along a proximal edge thereof for releasably securing blade  114 ′ within ferrule  112  in a manner hereto for described. 
     With reference now to  FIGS. 15 and 16 , a general description of a preferred method of manufacturing a broadhead in accordance with the present invention will now be described. A more detailed description is set forth in U.S. application Ser. No. 09/546,146 filed on Apr. 10, 2000 and entitled “Broadhead and Method Of Manufacture”, the disclosure of which is expressly incorporated by reference herein. The method of manufacture is schematically illustrated in flow chart  100 . 
     The manufacturing process is initiated by blending metal powder and binder to form a powdered metal composition as represented at block  102 . When blending, the metal powder and binder are typically premixed in a first blending step  102 a and then fully mixed to a near homogenous mixture and pelletized in a second blending step  102 b. In this regard, a particular metal such as high carbon steel or titanium is mixed with a suitable binder such as a plastic or wax to form a powdered metal composition. Alternatively, plastic, ceramic or composite materials suitable for powder injection molding (PIM) may be substituted for the powdered metal composition described above. Next, as represented in block  104 , the powdered metal composition is injected into a broadhead mold  105  having the particular design configurations for fabricating ferrule  12  and collar  16  illustrated in  FIGS. 1-8 , or alternately for fabricating ferrule  112 , cutting blade  114  and/or tip  118 . One skilled in the art will recognized that the various PIM components of broadhead  110  are formed separately. Through the use of pressure or other means, the powdered metal composition is compacted into a greenware broadband component having the precise geometric configuration of the final product (although approximately 20% larger than the end design to account for shrinkage during subsequent processing) and moderate densification (on the order of approximately 50 densification). 
     Next, as represented in block  106 , the greenware broadhead component is processed to eliminate the binder from the metal without melting the constituent metal, thereby forming a powdered metal broadhead component. As presently preferred, the greenware broadhead component is immersed in a solvent to separate a portion of the binder from the powdered metal as illustrated in block  106 a. The greenware broadhead component is removed from the solvent and placed in a thermal debinding furnace represented at block  106 b where any remaining binder is burned off. The thermal debinding furnace may also be employed to perform a pre-sintering step. While the debinding steps is described as a combination of chemical and thermal processes, one skilled in the art will readily recognize that any process or combination of processes could be employed to debind the greenware broadhead. At this point, the powdered metal broadhead component is still in a moderate densification state. 
     As represented at block  108 , the powdered metal broadhead component is next placed in a sintering furnace and sintered at an elevated temperature and pressure to achieve near full density thereof. The sintering processing parameters are defined such that the broadhead reaches a density of at least 97%. During the sintering process, the overall size of the broadhead shrinks approximately 20%. Once sintering is complete, the broadhead component has a net shape and does not require further machining. In addition, the various features including slots, bosses and threaded shanks are already formed in the ferrule. Lastly, as represented at block  110 , cutting blades are secured to the ferrule in a final assembly process of the broadhead. 
     As presently preferred, the broadhead components of the present invention are fabricated using a powdered metal technology. However, one skilled in the art will readily recognize that other powdered materials such as ceramics or plastics may be suitable, and thus utilized herein. The determination of the exact materials are dictated by the requirements of a given application. 
     From the foregoing description, one skilled in the art will readily recognize that the present invention is directed to an archery broadhead design and a method of manufacturing same. While the present invention has been described with particular reference to preferred embodiments, one skilled in the art will recognize from the foregoing discussion and accompanying drawings and claims, that changes, modifications and variations can be made in the present invention without departing from the spirit and scope thereof as defined in the following claims.