Abstract:
A broadhead for an arrow having a reduced amount of interference in the pivotal range of travel of the cutting blades, thereby allowing the cutting blades to pivot to a predetermined deployed position. The broadhead generally includes a body portion having a circular cross-section and defining a proximal end and a distal end, a post member extending from the proximal end having an outer diameter less than an outer diameter of the body portion, a pointed tip at the distal end of the body portion, at least one cutting blade secured to the body portion and configured to be movable from a retracted position to an expanded position; and a washer configured to be positioned over the post member and adjacent the outer peripheral surface, the washer having at least one chamfer formed thereon. An elastic ring may be provided around the cutting blades to maintain the cutting blades in an undeployed, retracted position. The retracted blade assembly may also be fixedly secured to enable the user to utilize the broadhead as a target point.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a broadhead for an arrow having expanding cutting blades and, more particularly, to a broadhead having cutting blades which are held in an undeployed retracted position and moved to a deployed expanded position when the broadhead strikes a target. 
     2. Description of the Prior Art 
     Broadheads having cutting blades which are held in an undeployed retracted position and moved to a deployed expanded position when the arrow strikes a target are well known in the art. Broadheads designed with deployable cutting blades overcome the problems associated with wind drag and other adverse wind effects during the flight of the arrow. For example, U.S. Pat. No. 5,112,063 to Puckett discloses a broadhead having deployable cutting blades which are kept in a retracted position during the flight of an arrow by a tubular external restraint which fits over the ferrule of the broadhead. When the broadhead impacts against a target, such as an animal, a deployment mechanism causes the blades to be deployed, cutting the tubular restraint from the ferrule. 
     Various means for securing the expanding cutting blades to the ferrule of the broadhead have been developed in an effort to provide an aerodynamically balanced arrow with the capability of instantaneously deploying the cutting blades upon the arrow striking the target. Pivotable connecting pins are typically utilized for securing expanding cutting blades to the broadhead as disclosed in, for instance, U.S. Pat. No. 3,600,835 to Hendricks, U.S. Pat. No. 4,099,720 to Zeren, and U.S. Pat. No. 5,090,709 to Johnson, among others. Many other prior art broadheads provide pivotably connecting pins linking the expanding cutting blades to a plunger mechanism which causes the blades to deploy once the arrow strikes the target. These are disclosed in, for instance, U.S. Pat. No. 5,102,147 to Szeluga, and U.S. Pat. No. 5,112,063 to Puckett, among others. 
     The broadhead is typically secured to an arrow shaft via a threaded end portion of the broadhead. The threaded end portion may be threaded directly into the end of the arrow shaft. However, it is more common for the threaded end portion to be threaded into an insert which is secured within the end of the arrow shaft. A round flat washer is typically placed over the threaded end portion of the broadhead prior to joining the broadhead with the arrow shaft. In either case, either the washer or the end of the arrow shaft forms a shoulder which restrains the blades of the broadhead from deploying past a fixed point (i.e., the edge of the shoulder). 
     The shoulders formed by the structure associated with prior art broadheads and arrow shafts cause several disadvantages which may affect the performance of the arrow during use. For example, the edge of the shoulder puts stress on a single point of the blades which increases the possibility that a blade will crack upon impact with a hard surface, such as a bone of an animal. Also, the shoulder prevents blades from deploying in a further retracted position which may limit the penetration of the broadhead into the intended target. 
     The novel configuration of the washer used in connection with the broadhead of the present invention obviates the disadvantages encountered in the prior art by providing a means for distributing the stress exerted by the washer over a larger surface area of the blades while allowing the blades to deploy in a further retracted position. 
     SUMMARY OF THE INVENTION 
     The present invention provides a broadhead for an arrow having a reduced amount of interference in the pivotal range of travel of the cutting blades, thereby allowing the cutting blades to pivot to a predetermined deployed position which is further than prior art blades are able to deploy. 
     In a first embodiment, the broadhead generally includes a body portion having a circular cross-section and defining a proximal end and a distal end, a post member extending from the proximal end having an outer diameter less than an outer diameter of the body portion, and an outer peripheral surface protruding from the proximal end concentrically about the post member thereby defining a circular gap between the outer peripheral surface and the post member; a pointed tip at the distal end of the body portion; at least one cutting blade secured to the body portion and configured to be movable from a retracted position to an expanded position; and a washer configured to be positioned over the post member and adjacent the outer peripheral surface, the washer having at least one chamfer formed thereon. 
     In a second embodiment, the broadhead generally includes a body portion having a circular cross-section and defining a proximal end and a distal end, a post member extending from the proximal end having an outer diameter less than an outer diameter of the body portion; a pointed tip at the distal end of the body portion; a plurality of cutting blades secured to the body portion and configured to be movable from a retracted position to an expanded position; and a washer configured to be positioned over the post member and adjacent the outer peripheral surface, the washer having a plurality of chamfer formed thereon and aligned with the plurality of cutting blades. 
     Alternatively, where a washer is not utilized, an insert or an end of an arrow shaft, within which the first end portion of the body member is inserted, may be chamfered to reduce the amount of interference in the pivotal range of travel of the cutting blades, thereby allowing the cutting blades to pivot to a predetermined deployed position. 
     A retaining means, such as an elastic o-ring, may be secured around the cutting blades and fit into a notch on each cutting blade to maintain the cutting blades in an undeployed retracted position. The retaining means is disengaged from the notches when the broadhead strikes a target due to the force exerted by the target on the portion of the cutting blades partially extending from the slots. As a result, the cutting blades move into a deployed expanded position causing the area of impact on the target to be enlarged. 
     A second retaining means, such as a wire or string, may be secured around the cutting blades and fit into a second notch on each cutting blade to hold the cutting blades in an undeployed position so that the broadhead may be utilized as a target point if desired. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the invention, reference is made to the following description of exemplary embodiments thereof, and to the accompanying drawings, wherein: 
     FIG. 1 illustrates a perspective, partially exploded view of an arrow having the broadhead of the present invention secured to an insert for assembly to the arrow shaft, with the cutting blades in the undeployed retracted position; 
     FIG. 2 illustrates a perspective, partially exploded view of the arrow of FIG. 1 having the broadhead of the present invention with the cutting blades in the expanded position; 
     FIG. 3 illustrates an exploded view of the broadhead of the present invention showing its novel washer design; 
     FIG. 3 a  is a cross section of the broadhead of the present invention taken along line  3   a — 3   a  of FIG. 3; 
     FIG. 4 illustrates a side-view in partial cross-section of the assembled broadhead and novel washer design; 
     FIGS. 5 and 6 illustrate the movement of the cutting blades from an undeployed retracted position to a deployed expanded position as the arrow strikes a target; 
     FIGS. 7-9 illustrate a method for removing the cutting blades from the broadhead of the present invention; 
     FIG. 10 illustrates a side view of the broadhead in the undeployed position with the blades secured for use of the broadhead as a target point; 
     FIG. 11 illustrates a perspective view of the end of an arrow shaft having a chamfered surface; and 
     FIG. 12 illustrates a perspective view of an insert having a chamfered surface. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now in specific detail to the drawings, in which like reference numerals identify similar or identical elements throughout the several views, FIG. 1 illustrates an exploded view of a broadhead  10  of the present invention secured to a shaft  12  of an arrow  14 . Broadhead  10  includes a pointed tip  16  and cutting blades  18  attached to a tapered body portion  20 . Cutting blades  18  include a cutting edge  22  and a notch  23  on a side opposite the cutting edge  22 . The blades are secured to broadhead  10  by a securement mechanism and maintained in an undeployed retracted position by an elastic ring  25  which engages the notch  23  of each cutting blade  18 . A second notch  24  is formed in each cutting blade  18  to facilitate utilizing broadhead  10  as a target point as further discussed below. 
     As used herein, the term “proximal end” refers to the end of the broadhead which attaches to the arrow shaft, and the term “distal end” refers to the pointed tip end of the broadhead. 
     As best seen in FIG. 2, slots  26  extend along a major portion of a longitudinal axis of tapered body portion  20  for partially inserting expanding cutting blades  18  while in the undeployed retracted position. Broadhead  10  may be secured to the arrow shaft  12  by cylindrical insert  38  as described below, by a locking mechanism as disclosed in U.S. Pat. No. 5,354,068, the contents of which are incorporated herein by reference, or by any other means known to one having ordinary skill in the art. FIG. 2 illustrates the broadhead of the present invention in which the elastic ring  25  has been moved proximally along the cutting blades  18  as the blades moved toward a deployed expanded position. 
     FIG. 3 illustrates the assembly of the cutting blades  18  to broadhead  10 , and FIG. 4 illustrates a cross-section of the fully assembled broadhead  10 . As seen in FIG. 3, pointed tip  16  is frictionally fit, threaded or press fit in a conventional manner onto a distal first end of tapered body portion  20  of broadhead  10 . A post member  28  having a smaller diameter than the outer diameter of tapered body  20  extends proximally from the tapered body portion  20  at an end opposite the first end and pointed tip  16 . The post member  28  includes a threaded portion  29  for facilitating connection of broadhead  10  to shaft  12  as further described below. A circular wall  30  also extends from the end opposite the pointed tip  16 , specifically from the outer peripheral surface of tapered body portion  20 . A circular gap  32  is thus formed between circular wall  30  and post member  28 , as illustrated in FIG. 3 a.    
     The mechanism for securing cutting blades  18  to broadhead  10  comprises a ring  34  for holding the cutting blades  18  as a single replaceable ring/cutting blade assembly within the circular gap  32 . A washer  36 , and a cylindrical insert  38 , which is insertable into the end of arrow shaft  12  as shown in FIG. 1, lock the ring/cutting blade assembly in position. Each cutting blade  18  includes a hole  44  at one end for coupling with ring  34  to form the ring/cutting blade assembly. It is also contemplated that blades  18  may be pivotally attached to broadhead  10  by a pin or other means known to one having ordinary skill in the art. 
     To secure the expanding cutting blades  18  to the broadhead  10 , the ring/cutting blade assembly is first placed over the post member  28  and the cutting blades  18  are aligned with the slots  26 . The alignment of the cutting blades  18  within the slots  26  also aligns the cutting blades  18  with the longitudinal axis of the broadhead  10 , since the slots  26  are properly aligned with the longitudinal axis of the tapered body portion  20  during the manufacture of the broadhead  10 . This obviates the requirement for exact precision measurements present in the assembly of broadheads while providing a precise alignment of the cutting blades  18  with the longitudinal axis of the broadhead  10 , which ensures that the assembled broadhead  10  will be properly balanced for accuracy in flight. It is also contemplated that slots  26  may be formed in such a manner as to be out of alignment with the longitudinal axis of broadhead  10 . 
     After the ring/cutting blade assembly is placed over post member  28 , washer  36  is then placed over post member  28 . The washer  36  is typically constructed of a hardened steel or similar material, to facilitate the forcing of the ring cutting blade assembly into position within circular gap  32  as will be described below. The ferrule, blade and washer assembly are then joined to an arrow, as illustrated in FIGS. 1 and 4, having the cylindrical insert  38  in place on the distal end of the arrow shaft  12 . Insert  38  includes a central bore  40  having an internal threaded portion  42 . While the cutting blades  18  are held within their respective slots  26 , the insert  38  and arrow shaft  12  are rotated so that the threaded portion  29  of the post member  28  engages the internal threaded portion  42  of the cylindrical insert  38 . 
     As insert  38  and arrow shaft  12  are rotated onto post member  28 , the distal end  43  of insert  38  engages washer  36 , forcing washer  36  to move distally towards tapered body portion  20 . As the cylindrical insert  38  and arrow shaft are further rotated, washer  36  contacts the proximal ends of cutting blades  18  near the area where ring  34  is attached to each cutting blade  18 . The washer  36  applies pressure to the cutting blades  18  forcing ring  34  to compress slightly and become wedged in circular gap  32  formed between post member  28  and circular wall  30  extending from tapered body portion  20 , thereby firmly securing the ring/cutting blade assembly to the broadhead  10 . While the washer  36  facilitates the forcing of ring  34  into circular gap  32 , it may be eliminated, and the distal end  43  of insert  38  may be utilized to force ring  34  distally. In this case, the material of which the insert  38  is constructed may be steel or a material of like hardness. 
     The elastic o-ring  25  engages notch  23  on each cutting blade  18  for maintaining cutting blades  18  at least partially within slots  26  while cutting blades  18  are in an undeployed retracted position. The elastic o-ring  25  disengages the notches  23  when the arrow  14  strikes a target  48 , as seen in FIGS. 5 and 6, to enable the cutting blades  18  to move into a deployed expanded position as explained below. 
     It is also contemplated that the cylindrical insert  38  may be provided without a threaded portion  42  and be constructed of a material that is self-tapping, such as aluminum. Rotation of the aluminum insert  38  over the post member  28  would cause the threaded portion  29  of the post member  28  to create internal threads on the inner surface of cylindrical insert  38 . In addition, it is further contemplated that the threads may be eliminated in both the post member  28  and the shaft  38 , so that post member  28  is forced into the central bore  40 , and is held in place through the use of, for example, a raised detent. 
     When the arrow  14  strikes a target  48 , the pointed tip  16  of the broadhead  10  pierces the target  48  as illustrated in FIG.  5 . As the arrow  14  continues to penetrate the target  48 , the area immediately surrounding the point of entry makes contact with the portion of the cutting blades  18  partially extending from the slots  26 . The force applied by the target  48  on the cutting blades  18  causes the blades  18  to move in a direction opposite the target  48 . This motion causes the elastic ring  25  to be forced rearwardly and disengage the notches  23 , to enable the cutting blades  18  to move into a deployed expanded position as illustrated in FIG.  6 . The expanded cutting blades  18  thus cut and enter the target  48  causing the area of impact to be enlarged. 
     The range of travel of cutting blades  18  is, however, limited by washer  36  (or by the end of insert  38  when the washer  36  is not used). As discussed above, in prior art broadheads, washer  36  was manufactured in the shape of a common flat washer. Therefore, the range of travel of each cutting blade  18  was limited to the point where cutting blades  18  were only being deployed to a position which was slightly beyond perpendicular to the longitudinal axis of broadhead  10 . More specifically, cutting blades  18  could only deploy to a point where the back of the blade hits the edge of washer  36 . In the fully deployed position, cutting blades  18  contact and rest upon a hard edge of washer  36 . 
     To allow cutting blades  18  to deploy further in the proximal direction than the prior art broadheads would allow, washer  36  of the present invention includes chamfers  37  on washer  36  (as best illustrated in FIGS.  3  and  4 ). The number of chamfers  37 , and spacing therebetween, corresponds to the number and spacing of cutting blades  18  in the broadhead. In accordance with the present invention, in the fully deployed position, cutting blades  18  will rest on the chamber surface rather than a hard edge of a regular washer used in the prior art broadhead assemblies. Chamfers  37  are preferably formed by machining or grinding an edge of a common flat washer at predetermined locations. It is also contemplated that a chamfered surface  37  may be formed on an end of an arrow shaft  12  or on an insert  38  as shown in FIGS. 11 and 12, respectively. 
     To utilize broadhead  10  as a target point, blades  18  can be prevented from deploying by being tied to the broadhead  10  as illustrated in FIG.  10 . Specifically, a string or wire  46 , or the like, is used to tie cutting blades  18  to the broadhead  10  by winding the string  46  around the distal notch  24  on each cutting blade. In this configuration the cutting blades  18  will be held in the undeployed position when the broadhead  10  strikes the target  48 , such that the broadhead  10  may be utilized as a target point. 
     FIGS. 7-9 illustrate a method for removing cutting blades  18  from the broadhead  10  of the present invention. For simplicity, the arrow shaft has been eliminated from the drawings. First, as shown in FIG. 7, the broadhead  10  is partially removed from insert  38  by partially unthreading post member  28 . The elastic ring  25  is disengaged from the notches  23  enabling the cutting blades  18  to swing towards the insert  38 . As shown in FIG. 8, tapered body portion  20  of the broadhead  10  is placed against a block  50 , preferably having a cylindrical bore  52 , although any surface having a bore will suffice. The bore  52  preferably is narrower than the cross section of the cutting-blade assembly, thus preventing the cutting blades  18  from entering the bore  52 . The end of the arrow shaft, or insert  38 , is then placed over a hard, durable surface  54 , as illustrated in FIG.  9 . The block  50  is pushed toward the surface  54  causing pressure to be applied to each cutting blade  18  at a point near where the ring  34  is connected to each cutting blade  18 . This action also causes pressure to be applied to the ring  34  in a direction opposite the pointed tip  16 . The pressure disengages the ring  34  from the circular gap  32 . The insert  38  is then fully unthreaded and the broadhead  10  is removed, which enables the removal of the ring cutting blade assembly. A new set of cutting blades  18  with their associated ring  34  can then be placed over the post member  28  and secured to the broadhead  10  as a single replaceable unit as described above. Alternatively, tapered body portion  20  may be placed on a surface having a bore, and the arrow shaft may be used to push downwardly on the broadhead  10  whereby the blades  18  are forced proximal to the tip  16  for removal. 
     Although the illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one having ordinary skill in the art without departing from the scope or spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the appended claims.