Patent Document

CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from U.S. Provisional Patent Application Ser. No. 61/870,986, filed on Aug. 28, 2013, the contents of which are herein incorporated by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates generally to arrows suitable for use with bowfishing and in particular to an arrow tip suitable for use in bowfishing. 
         [0003]    Bowfishing is an archery technique using specialized bows and arrows for fishing. A bowfishing bow may have a lower draw weight than a standard bows as well as a constant draw to allow rapid and frequent shooting without tiring the archer. The bowfishing bow may have bowfishing line stored in a canister or reel attached to the bow. One end of the bowfishing line is attached to the arrow so that when the arrow is released, the line pays out allowing the arrow and fish to be retrieved by reeling the line in. A bowfishing reel suitable for use in this purpose is described in U.S. Pat. Nos. 4,383,516 and 6,634,350 by the inventor of the present invention and hereby incorporated, by reference. The line may be attached to the arrow using a slide that moves freely up and down the arrow shaft. Before the arrow is released, the slide may be positioned in front of the arrow rest and bowstring and may remain in front of the arrow rest as the arrow is released to reduce risk of entangling either the bow or the bowstring. Slides suitable for this purpose are described in U.S. Pat. No. 6,517,453 also by the inventor of the present invention and hereby incorporated by reference. 
         [0004]    The arrows used for bowfishing are normally fashioned out of high-strength fiberglass or carbon fiber composites to better survive impact with a stony bottom of a lake or stream. For similar reasons, the arrow tips used for bowfishing are designed with the expectation that they may strike hard surfaces. A common arrow tip for bowfishing, provides a compact cylindrical body of hardened steel or the like having a pyramidal tip formed of 3-6 flat or hollow ground faces tapering to a point. The faces abut each other at sharp edges to provide a cutting action as the arrow tip passes into the fish. 
         [0005]    The arrow tip may attach to the fiberglass arrow shaft by means of a threaded adapter, the latter providing an interface between the arrow tip and the arrow shaft. Generally the threaded adapter receives the arrow shaft in a blind bore in the rear of the threaded adapter. 
         [0006]    The arrow shaft is held within the bore, for example, with epoxy or the like. An opposite end of the threaded adapter provides a threaded stud or socket that may engage a corresponding socket or stud on the arrow tip. This threaded connection allows damaged arrow tips to be readily replaced by unthreading the arrow tip from the threaded adapter and threading a new arrow tip in its place. 
         [0007]    The threaded adapter may provide sidewardly extending barbs that help retain the fish when the arrow is retrieved. In some cases, the barbs are held extended by the presence of the arrow tip as attached to the threaded adapter. In these cases, the arrow tip may be unscrewed to allow the barbs to be retracted or reversed to assist in removing the fish from the arrow. 
         [0008]    It will be understood that it is important that the arrow tip be readily removable for replacement when it is damaged and in some cases for a resetting of the barbs for extraction of the arrow from the fish. Yet the vibration of impact after repeated shots can cause the arrow tip to become unthreaded and lost. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides an arrow tip suitable for bowfishing having spiral cut faces and edges. In one embodiment, the spiral coordinates with the threaded engagement between the arrow tip and the adapter so that impact of the arrow tip against stones or the like and passage of the arrow tip through the water tend to tighten the arrow tip to prevent its loss. 
         [0010]    Specifically one embodiment of the invention provides an arrow tip having a tip body with an outer wall extending about a central axis. A point is formed at a front end providing a tapering inward of the outer walls towards the central axis to an apex on the central axis, wherein the point is formed from a plurality of faces joined at circumferentially abutting edges, the faces and edges extending about the axis in a helical path. A threaded attachment at a rear end of the tip extends along the axis to receive a second threaded attachment on an arrow shaft to releasably attach the arrow tip to the arrow shaft by rotationally threading the threaded attachment on the second threaded attachment. 
         [0011]    It is thus a feature of one embodiment of the invention to provide a substantially new form of sharpened point on an arrow. 
         [0012]    The apex may be a point of convergence of the helical faces and edges. 
         [0013]    It is thus a feature of at least one embodiment of the invention to provide an arrow tip that converges to a point for superior penetration. 
         [0014]    The helical faces and helical edges may run counterclockwise with respect to the central axis of the tip body viewed from the front end. 
         [0015]    It is thus a feature of at least one embodiment of the invention to provide a helical form that conforms to standard right-handed threads. 
         [0016]    The faces may be hollow wound. 
         [0017]    It is thus a feature of at least one embodiment of the invention to permit multiple faces while preserving relatively sharp edges that resist dulling. 
         [0018]    The helical faces and helical edges may have a rotational sense relative to the threaded attachment tending to tighten the threaded attachment when the tip passes through a resisting material with the apex in a leading position. 
         [0019]    It is another feature of at least one embodiment of this invention to provide an arrow tip with helical faces that tend to tighten the arrow tip onto the arrow shaft when the arrow tip strikes a surface. 
         [0020]    The tip may be part of an arrow providing a linear shaft, a nock, an adapter, and at least one arrow barbs that are retained against some range of movement by the tip. 
         [0021]    It is thus one feature of at least one embodiment of the invention to provide a tip that may be retained on the arrow with only finger tightening so that it may be loosened for release of the barbs and yet which will resist dislodgment when the arrow strikes water, fish, or a hard surface. 
         [0022]    These particular features and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is an exploded, side elevational view of one embodiment of the arrow tip of the present invention as may be received on a barbed adapter attached to an arrow shaft: 
           [0024]      FIGS. 2   a  and  2   b  are front and rear views of the arrow tip of  FIG. 1  showing the spiral edges and spiral faces of the arrow tip and the threaded socket of the arrow tip; 
           [0025]      FIG. 3  is a side elevational view of a machining apparatus for cutting spiral edges on the arrow tip; 
           [0026]      FIG. 4  is a top plan view of the machining apparatus of  FIG. 3 ; 
           [0027]      FIGS. 5-8  are left elevational, front elevational, rear elevational, and right elevational views of the arrow tip  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    Referring now to  FIG. 1 , an arrow  10  for use with the present invention may provide for a carbon fiber or fiberglass arrow shaft  12  having a cylindrical cross-section, for example, 5/16 inch in diameter and approximately thirty-two inches long. A rear end of the arrow shaft  12  provides an arrow nock (not shown). 
         [0029]    A front end of the arrow shaft  12  may attach to an adapter  14  by being received within a blind bore socket  16  of equal diameter in the adapter  14 . The arrow shaft  12  may be held, within the socket  16  with epoxy  18  or the like. 
         [0030]    The adapter  14  may provide a generally cylindrical metal body supporting the bore socket  16  at a rear end and extending along an axis  20  common to the arrow shaft  12  to terminate at a threaded boss  22  at a front end. An arrow tip  24  also extending generally along axis  20  and having a rearwardly-threaded bore  26  (also shown in  FIG. 2   b ) may receive the threaded boss  22  to attach the arrow tip  24  to the adapter  14 . 
         [0031]    Pivoting barbs  28  may be attached to the adapter  14  to extend outwardly from the adapter  14  and back toward the arrow shaft  12 . These barbs  28  help retain a fish on the arrow  10  after the arrow tip  24  and the adapter  14  and barbs  28  have passed through a fish. In order to remove the fish from the barbs  28 , the barbs  28  may fold flat against the adapter  14  (when the arrow tip  24  has been loosened or removed from the threaded boss  22 ). When the arrow tip  24  is attached to the threaded boss  22 , the barbs  28  may rest against the adapter  14  or may extend such that they are perpendicular to the adapter  14 . However, the barbs  28  are prevented from extending further than perpendicular to the adapter  14  as long as the arrow tip  24  is attached to the threaded boss  22 . An arrow and barb system suitable for the present invention is described in U.S. patent application Ser. No. 14/457,677 hereby incorporated by reference. 
         [0032]    One or both of the threaded boss  22  and threaded bore  26  may be coated with a locking polymer  31  (or may incorporate a polymer insert) serving to lock, the threads together by deformation of the polymer  31  coupled with engaging of the threads of the threaded boss  22  and threaded bore  26  together. The locking polymer  31  allows the arrow tip  24  to better resist vibration induced when the arrow is shot, preventing unthreading from the threaded boss  22 . 
         [0033]    Referring now to  FIGS. 1 and 2   a , the arrow tip  24  provides for a cylindrical body  30  holding the threaded bore  26  and substantially equal in diameter to the adapter  14  as it attaches to the adapter  14 . The cylindrical body  30  extends along the axis  20  to a forward tip  33  of the arrow tip  24 , the latter of which is sharpened to a point  32 . In particular, forward tip  33  is formed by a set of converging flat or hollow ground spiral faces  34  converging at the point  32 . The spiral faces  34  abut along spiral edges  36 . The spiral faces  34  and spiral edges  36  define a helical path running clockwise to the axis  20  from threaded bore  26  to point  32 . In one embodiment five spiral faces  34  are provided (as depicted); however, the invention contemplates that between three and six spiral faces  34  and preferably at least five spiral faces  34  will normally be employed. 
         [0034]    In one embodiment, the spiral faces  34  and spiral edges  36  curve in a counterclockwise direction as viewed from the point  32 . In this case the thread of the threaded boss  22  may be a standard right-hand thread allowing the arrow tip  24  to tighten on the boss  22  with clockwise rotation of the arrow tip  24  as viewed from the point  32 . It will be appreciated that as the arrow  10  flies, impacts with a stationary surface or passage through a medium such as water will cause the spiral faces  34  or spiral edges  36  to impart a clockwise torsion on the arrow tip  24  tending to tighten the arrow tip  24  onto the adapter  14 . 
         [0035]    Referring now to  FIG. 3 , the arrow tip  24  may be fabricated from a stainless, titanium, or hardened steel cylinder  38  providing the cylindrical body  30  of the arrow tip  24 . The cylinder may have a diameter of ¼″ to ⅝″, A cutter  40  is rotated about an axis  42  parallel to an axis  20  (along which the cylindrical body  30  extends) to cut the faces  34 . The cutter  40  may be a carbide tool or the like, as shown, or the surface of a grinding wheel or other similar cutting mechanism. The radius of rotation of the cutter  40  in an arc about axis  42  defines a hollow cut of the faces  34 . This hollow face sharpens the edges  36  beyond that which could be obtained by a simple faceting and provides edges that better resist dulling in the manner of a hollow ground knife-edge. 
         [0036]    A pyramidal tapering of the faces  34  to the point  32  may be provided by an angled translation of the center of rotation of the cutter  40  along a taper path  46  following an angle of a taper of the arrow tip  24  while preserving a parallel alignment between the axis  42  and axis  20 . A spiraling of the faces  34  is provided by slight rotation  48  of the cylindrical body  30  about axis  20  as the arc of the cutter  40  is translated along path  46 . The amount of rotation  48  during the full translation along path  46  is preferably between two and  30  degrees. In order to provide the desired spiraling described above, the rotation  48  may be counterclockwise as the cutter  40  moves upward along path  46  as depicted in  FIG. 3 . 
         [0037]    It will be appreciated that the spiral faces  34  are at all times circumscribed by the cylinder defined by the cylindrical body  30  and that the arrow tip  24  may be of unitary construction machined from a single cylinder of metal. 
         [0038]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
         [0039]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”. “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0040]    It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications are hereby incorporated herein by reference in their entireties.

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