Abstract:
A broadhead arrow having a body and at least two removable blades attached to the body. The blades being locked into a place by a lock washer that slides over the rear portion of the body and is secured between the broadhead point and the arrow shaft. Removal of the washer allows for easy removal and replacement of the blades.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/419,514 filed Dec. 3, 2010, the specification of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to archery arrow tips, and more particularly to archery broadhead arrow tips. 
     BACKGROUND OF THE INVENTION 
     Broadheads are often used by bow hunters while hunting large game animals. The broadhead generally has two or more sharp blades extending from the point. The blades form a wide cutting edge that cause massive bleeding once striking the target. 
     Broadheads are used in hunting popular big game animals such as deer, elk, antelope, bear, and elephants. The broadhead promotes internal bleeding upon impact as opposed to the shock or concussion produced by a rifle bullet. 
     Broadheads must be designed such that they can penetrate the hide, and in some circumstances, the bone of the target animal. Ideally, the hunter will aim for the lungs, or other vital organs of the animal to achieve a fast kill. The extended blades of the broadhead provide a large cutting surface to quickly bring down the target animal. 
     There are two main types of broadheads used today, mechanical broadheads and fixed-blade broadheads. Mechanical broadheads deploy the blades upon contact with the target. Mechanical broadheads are more streamlined in flight but are less effective at penetrating the target as a portion of the impact energy is absorbed to deploy the blades. 
     Fixed-blade broadheads have blades that are fixed into the open position. While sacrificing some flight characteristics, fixed-blade broadhead cut on impact in a much more efficient manner than mechanical broadheads. The blade creates a better wound channel for blood flow improving the likelihood of developing a good blood trail. The fixed-blade broadhead generally cuts deeper because it does not loose energy in the process of opening the blades as is common with mechanical broadheads. Fixed-blade broadheads are also stronger than comparable mechanical broadheads as there are no moving part. For these reasons fixed-blade broadheads are preferred by most hunters. 
     The blades occasionally become damaged thereby making the broadhead unusable. Sticking a hard object such as a tree, rock or even some bones can deform the broadhead blade. Shooting a deformed broadhead can result in erratic arrow flight. Shooters may have preference for distinct blade styles depending on the conditions. Also in certain jurisdictions, particular designs are prohibited. 
     Therefore, a broadhead having replaceable blades is desired. 
     SUMMARY OF THE INVENTION 
     The invention comprises, in one form thereof, a broadhead having removable blades. The removable blades fit into a series of recessed portion found in the broadhead body and are locked into place with a locking device such as a lock washer. The locking device is held between the tip and the arrow shaft. The inner diameter of the locking device retains the removable blades to the body. 
     More particularly, the invention includes a broadhead having a body with an axis, a threaded portion and a blade recess; a tip at a first end of the body; at least two removable blades having a cutting edge, a base and a blade lock, the base being fashioned to fit within the blade recess; and a lock washer having an inner bore sufficient to slide over the threaded portion and the base positioned in the blade recess to affix the removable blades to the body. 
     The invention includes many optional components listed in this paragraph. For example, the body may contain a washer stop to limit travel of the lock washer. Additionally, the blade recess may extend from the threaded portion and through the washer stop. Optionally, the tip has at least two tip blades that terminate at a common point. The tip blades may make a smooth transition to the removable blades. The tip may be removable or may be integrated into the housing body. A large portion of the total mass of the removable blades is located behind the rear portion of the lock washer, that is the end away from the tip. This may be at least 50% of the total mass of the removable blade and may also be at least 75% of the total mass. Optionally, the removable blades have a relatively steep angle and may be between 25 and 50 degrees relative to the axis of the body; in one embodiment the angle may also be more narrowly defined between 32 and 43 degrees. The removable blades may also contain a rear edge extending from the end of the cutting edge to a blade opening, the blade opening allowing the locking device to travel between the base and the cutting edge. The rear edge may extend substantially orthogonal to the axis of the body. The broadhead may have 2, 3, 4, 5 or 6 removable blades with 3 removable blades being the most common configuration. Optionally, when placing the removable blades into the blade recess, the blade lock on the removable blade aligns with the washer stop on the body to form a continuous edge along the circumference of the body. 
     The broadhead has a short overall length. This better aligns the concentricity ferrule axis with the shaft axis. The shorter length improves arrow flight and reduces the arrow fletching profile. 
     In another form, the invention includes a removable blade having a cutting edge with a blade angle; a base and a blade opening beginning at the end of the base and extending to a blade lock. Optionally, the removable blade may contain any of the features discussed above. 
     In yet another form, the invention includes a broadhead body having an axis with a first and second end; a treaded portion at the first end; a blade recess for receiving removable broadhead blades and a washer stop to limit travel of a locking device. Optionally, the broadhead body may contain any of the features discussed above. 
     In another form, the invention includes a method for assembling a broadhead. The method comprises the steps of providing a body having an axis, a threaded portion and a blade recess; inserting at least two removable blades comprising a cutting edge, a base and a blade lock, into the blade recess; and securing a lock washer over the threaded portion and the base positioned in the blade recess to affix the removable blades to the body. 
     An advantage of the present invention is that the blades are easily removable. 
     A further advantage of the present invention is that the by positioning more mass away from the tip, the arrow flight is more predictable. 
     An even further advantage of the present invention is that a shorter overall length of the broadhead allows the arrow flight to be similar to a field or practice point. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is disclosed with reference to the accompanying drawings, wherein: 
         FIG. 1  is an exploded isometric view of broadhead having removable blades according to one embodiment; 
         FIG. 2A  is a side view of the assembled broadhead shown in  FIG. 1 ; 
         FIG. 2B  is a front view of the assembled broadhead shown in  FIG. 1 ; 
         FIG. 2C  is an isometric view of the assembled broadhead shown in  FIG. 1 ; 
         FIG. 2D  is a cross sectional view of the broadhead shown in  FIG. 2A  taken across line A-A; 
         FIG. 3A  is a side view of an assembled broadhead according to another embodiment; 
         FIG. 3B  is a front view of the broadhead shown in  FIG. 3A ; 
         FIG. 3C  is an exploded isometric view of the broadhead shown in  FIG. 3A ; 
         FIG. 3D  is a cross sectional view of the broadhead shown in  FIG. 3A  taken across line A-A; 
         FIG. 4A  is an isometric view of the broadhead according to one embodiment; 
         FIG. 4B  is an exploded isometric view of the broadhead shown in  FIG. 4A ; 
         FIG. 5A  is a side view of an assembled broadhead according to one embodiment; and 
         FIG. 5B  is an exploded isometric view of the broadhead shown in  FIG. 5A . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The examples set out herein illustrate several embodiments of the invention but should not be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION 
     Referring to FIGS.  1  and  2 A- 2 D, there is shown a broadhead according to one embodiment. The broadhead  100  includes a body  110 , a tip  120 , removable blades  130 , and a lock washer  140 . 
     The broadhead body  110  has a threaded portion  111  proximate the rear end of the body  110 . The threaded portion  111  threads into an arrow shaft to attach the broadhead to the arrow. The broadhead body may be made from any suitable material such as, but not limited to stainless steel, carbon steel, aluminum, metals, ceramics and alloys. 
     The broadhead body further contains a number of blade recesses  112 . Generally the number of blade recesses corresponds to the number of blades attached to the body. However, it is understood that the body may contain more recesses to accommodate a wider variety of blade choices. For example, the body may contain six blade recesses but the user may only insert three blades into the body. Most common the broadhead body has between two and six blade recesses. In one embodiment, the body  110  has three blade recesses  112 . 
     The blade recesses  112  extend parallel along the axis of the body  110 . In one embodiment, the blade recess extends into the threaded portion  111  to allow a portion of the removable blade  120  to extend into the arrow shaft (not shown). This provides additional rigidity to the blade upon impact. Thereby decreasing the likelihood of a blade becoming detached. 
     In embodiments where a tip  120  is integrated with the body  110 , the body  110  further contains a washer stop  113 . The washer stop  113  limits travel of a locking mechanism such as a lock washer  140 . In one embodiment, the blade recesses  112  extend through the washer stop  113 , and they may even extend into the tip. 
     The tip  120  has a point  121  with a number of tip blades  122  extending from the point towards the rear of the tip  120 . Preferably, the tip  120  is integrated with the body  110  as a single component. However, it is understood that a removable tip may be used to allow further customization by the end user. The tip blades  122  terminate and form a rear seat  123 . When inserted, the leading edge  136  of the removable blade  130  abuts the rear seat  123  to form a continuous cutting surface from the point  121  to the trailing edge  137 . Preferably, the number of tip blades  122  correlates with the number of removable blades  130 . In one embodiment, the tip  120  has three tip blades  122 . Optionally, the tip  120  further contains depressions  124  or other design features to improve the flight characteristics or aesthetic properties of the broadhead. 
     The removable blades  130  contain a sharpened cutting edge  131  having a leading edge  136  and a trailing edge  137 . The blade base  132  is inserted into the blade recess  112  such that the top portion of the blade base  132  remains flush with the body  110 . The blade opening  133  proves a gap between the cutting surface  131  and the blade base  132 . Once inserted, the inner bore  141  of the lock washer  140  slides over the blade base  132  into the blade opening  133 . The front portion  142  of the lock washer  140  abuts the blade lock  134  of the removable blade  130  and the washer stop  113  of the body  110  to affix the removable blade  130  to the body  110 . In one embodiment, the washer stop  113  and the blade lock  134  form a continues edge along the circumference of the body  110 . The blade base  132  rests inside of the arrow shaft further securing the removable blade  130 . In one embodiment, the blade base is at least 3/32″ long; in another embodiment, the blade base is at least ⅛″ long; in yet another embodiment, the blade base is at least ¼″ long; and in a further embodiment, the blade base extends rearward beyond the plane defined by the trailing edge of the removable blade. 
     To improve flight characteristics of the arrow, the center of mass for the removable blade  130  is moved behind the blade lock  134  towards the trailing edge  137 . This provides an aerodynamic advantage and less wobble during arrow flight. Normal broad head changes the overall effective length of the arrow shaft bringing more mass “front of center.” The shorter broadhead more closely represents the trajectory of field or practice points and further reduces concentricity tolerance. When assembled to an arrow shaft, the cutting edge  131  overhangs the arrow shaft (not show). In one embodiment, at least 50% of the removable blade&#39;s  130  mass is located behind the rear portion  143  of the lock washer  140  when assembled. In another embodiment, at least 70% of the removable blade&#39;s  130  mass is located behind the rear portion  143  of the lock washer  140  when assembled. 
     Optionally, the removable blade  130  further contains a rear edge  135 . In one embodiment, the rear edge  135  is sharpened to a form a cutting surface. The rear cutting surface makes it easier to remove the broadhead by cutting through any obstructions. Alternatively, the rear edge  135  may be a smooth surface or contain a barbed design. 
     When affixed to the body  110 , the removable blades  130  provide a continuous cutting surface from the point  121  along the tip blade  122  and the cutting edge  131  to the trailing edge  137 . In one embodiment, taking the cutting surface from the point  121  to the trailing edge  137 , the cutting surface has an angle between 25 and 50 degrees relative to the center axis of the body  110 . In another embodiment, the cutting surface has an angle between 30 and 45 degrees relative to the center axis of the body  110 . In further embodiment, the cutting surface has an angle between 35 and 40 degrees relative to the center axis of the body  110 . The cutting surface may be linear from the point  121  to the trailing edge  137  or it may be slightly curved. 
     As discussed above, the lock washer  140  affixes the removable blades  130  to the body  110 . The front portion  142  abuts the blade lock  134  and when the body  110  is screwed into an arrow shaft (not shown), the arrow shaft presses against the rear portion  143  of the lock washer  140 . The lock washer  140  is effectively positioned between the blade lock  134  and the end of the arrow shaft (not shown) to prevent movement. It is understood that although a lock washer is described herein, that other suitable locking devices are envisioned. For example, the threaded portion on the body may extend to the washer stop to allow for the connection of a threaded nut. Furthermore, the locking device may be shaped to correlate with the washer stop of the arrow shaft to provide a more reliable fit. 
     Referring to  FIGS. 3A-3D , there is shown a broadhead design according to another embodiment. The broadhead contains a body  110 , tip  120  and lock washer  140  as described above. The removable blades  230  are similar to those shown in FIGS.  1  and  2 A- 2 D with the exception of the rear edge  235 . The rear edge  235  provides a more streamlined design which may be desirable. However, this design may not be permitted in all jurisdictions. Additionally, the removable blades  330  contain less material, thereby allowing for a lighter overall weight. It is understood that the optional features and alternative embodiments discussed above may further apply to this embodiment. 
     Referring to  FIGS. 4A-4B , there is shown a broadhead design utilizing an insert. The body  110  is screwed into an insert  250 . The insert  250  is housed inside the end of the arrow  260 . As the body  110  is screwed into the insert  250  the lock washer  140  is sandwiched between the insert  250  and the body  110 , thereby locking the removable blades  230  in place. In an alternative embodiment, the broadhead design does not include a lock washer. Instead, the insert or arrow shaft is used to lock the removable blades in place. 
     Referring to  FIGS. 5A-5B , there is shown a broadhead design according to another embodiment. The tip  320  is a portion of the body  310 . The blade base  332  of the removable blades  330  fits into the blade recess  312 . To provide additional support, the front blade tab  338  fits into the notch  325 . To provide additional support, a rear blade tab  339  may be used to lock the blade base  330  into a rear portion of the blade recess  312 . In one embodiment, the blade base  332  is shaped to correspond to the internal shape of the blade recess  312  to ensure a secure connection. As in the embodiments described above, a lock washer  340  slides over the blade base  332  and into the blade opening  333  to secure the removable blades  330  to the body  310 . When threaded into an arrow shaft, the end of the arrow shaft presses against the lock washer  340  and secures the removable blades  330 . When assembled the tip blade  322  and the blade cutting edge  331  are in the same plane. The blade cutting edge  331  terminating below the rearmost edge of the tip blade  322  to prevent the removable blade from catching upon impact. 
     In use, the broadhead may take on various shapes and sizes depending on the application. In one embodiment, the circumference of the broadhead measured along the circle formed by the trailing edge  137  of the removable blades  130  as shown in  FIG. 2B  is between 1.00 and 1.50 inches. More preferably, the circumference is between 1.20 and 1.30 inches. The distance from the point  121  to the trailing edge  137  is between 0.65 and 1.25 inches. In another embodiment, the distance from the point  121  to the trailing edge  137  is between 0.65 and 1.00 inches. In yet another embodiment, the distance from the point  121  to the trailing edge  137  is between 0.70 and 1.10 inches. The total length of the body from the tip to the rear end is between 1.25 and 1.85 inches. In another embodiment, the total length of the body from the tip to the rear end is between 1.40 and 1.75 inches. When installed, the distance from the tip to the front of the arrow shaft is less than 0.85 inches, preferable less than 0.75 inches and more preferable less than 0.70 inches. The distance horizontal along the axis from the leading edge  136  to the trailing edge  137  is between 0.70 and 1.10 inches. The length of the threaded portion is between 0.50 and 0.70 inches. The distance from the rear edge of the washer to the end of the threaded portion is between 0.60 and 0.80 inches. While these dimensions are provided for particular embodiments, it is understood that they are merely exemplary and are not intended to be limiting. 
     While the invention has been described with reference to particular embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope of the invention. For example, while a three blade design is shown in the  FIGS. 2 ,  4 ,  5  and  6  blade designs are envisioned. Furthermore, the locking mechanism described above may be utilized for mechanical broadheads. 
     Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope and spirit of the appended claims. 
     PARTS LIST 
     
         
           100  Broadhead 
           110  Body 
           111  Threaded Portion 
           112  Blade Recess 
           113  Washer Stop 
           120  Tip 
           121  Point 
           122  Tip Blade 
           123  Rear Seat 
           124  Depression 
           130  Removable Blade 
           131  Blade Cutting Edge 
           132  Blade Base 
           133  Blade Opening 
           134  Blade Lock 
           135  Rear Edge 
           136  Leading Edge 
           137  Trailing Edge 
           140  Lock Washer 
           141  Inner Bore 
           142  Front Portion 
           143  Rear Portion 
           230  Removable Blade 
           231  Blade Cutting Edge 
           232  Blade Base 
           233  Blade Opening 
           234  Blade Lock 
           235  Rear Edge 
           236  Leading Edge 
           237  Trailing Edge 
           240  Lock Washer 
           250  Insert 
           260  Arrow 
           310  Body 
           312  Blade Recess 
           320  Tip 
           322  Tip Blade 
           325  Notch 
           330  Removable Blade 
           331  Blade Cutting Edge 
           332  Blade Base 
           333  Blade Opening 
           338  Front Blade Tab 
           339  Rear Blade Tab 
           340  Lock Washer