Abstract:
Arrowheads, including blade-opening arrowheads as well as other non blade-opening arrowheads having a recessed collar or body that is slidably positionable about a stem portion thereof. The recess bounds and defines an internally contained void of the arrowheads. The collar is defined by having an internal centrally disposed bore extending therethrough so as to enable the collar or washer to be slidably positioned about an extending post or stem member of a corresponding arrowhead body. The collar and created internal void at least in part aid in attaching blades to the respective arrowhead bodies and serve to house various different annular elements that circumscribe the post member or equivalent.

Description:
This application is a Continuation of application Ser. No. 08/834,478, filed Apr. 11, 1997, now U.S. Pat. No. 6,287,224. 
    
    
     BACKGROUND—FIELD OF THE INVENTION 
     This invention relates to arrowheads having a recessed collar or body that is slidably positionable about a stem portion thereof. 
     BACKGROUND—DESCRIPTION OF PRIOR ART 
     Arrows have long been used for war, hunting and competitive sports. A conventional arrow has a shaft, a nock at one end that receives the bow string, an arrowhead or point that attaches to the opposite end, and fletchings. The fletchings are glued to the shaft near the nock end, and help to stabilize the arrow in flight, as it rotates. Arrowheads generally have a pointed forward end, and an opposite threaded shaft end that attaches the arrowhead to the arrow shaft. Arrowheads are also attached to the forward end of arrow shafts by glueing and other methods. 
     Arrowheads come in a variety of different sizes and configurations depending on their intended use. For example, there are specifically designed arrowheads for competitive target shooting, shooting fish, hunting birds or small game animals, and for hunting big game animals. 
     The most common type of arrowhead used in hunting is the fixed-blade arrowhead, which has a pointed tip end used for penetrating, and blades that each have a razor sharp edge for cutting. Most conventional fixed-blade arrowheads have replaceable blades which are held in a fixed position on the arrowhead. The replaceable blades attach to the arrowhead body in longitudinal grooves called blade slots. The tip of the arrowhead may be separably attachable to the arrowhead body or may be integral with it. Arrowheads for hunting are generally known as broadheads. 
     Arrowheads used for hunting kill the game animal by cutting vital organs such as the lungs and vascular vessels such as arteries, which causes rapid hemorrhaging and/or suffocation. Quick and humane kills are dependent on accurate shot placement, and upon the amount or volume of the animal tissue that is cut. Hunting arrowheads that cut more tissue are more lethal, and therefore are better. The volume of tissue that is cut is determined by the cutting diameter of the arrowhead, the number of blades it contains, and by the distance the arrowhead penetrates into the animal. The cutting diameter of an arrowhead is determined by how far each cutting blade extends outward from the arrowhead body. The further the blades extend outward the larger the cutting diameter is, and therefore the more cutting potential the arrowhead has. 
     A problem with conventional fixed-blade arrowheads is that having the desirable, large cutting diameters generally cause unstable arrow flight or poor arrow aerodynamics, which affects accurate shot placement. This can lead to non-lethal wounding of the game animal or missing the animal altogether. Unstable arrow flight in hunting arrows is generally caused by arrowhead aligning and centering problems. Arrowhead aligning and centering problems are prevalent when the arrowhead is attached to the arrow shaft such that the longitudinal axis of the arrowhead is not in line with the longitudinal axis of the arrow shaft. Alignment and centering problems in arrowheads are generally created by low tolerances or sloppiness in the manufacturing of the arrowhead body. When a mis-aligned arrowhead is attached to an arrow and the arrow is shot, as the arrow spins or rotates in flight non-stabilizing forces are induced on the front end of the arrow and cause inconsistent or erratic flight, which steers the arrow from its intended path. Since the cutting blades of fixed-blade arrowheads extend out from the arrowhead body when the arrowhead is in flight, the blades greatly magnify any non-stabilizing forces induced on the arrow from misalignment, and therefore increase erratic arrow flight. This is the main reason why conventional fixed-blade arrowheads are limited in the maximum cutting diameter they can have, while retaining sufficiently stable aerodynamics. 
     To create a hunting arrowhead that has both a maximum cutting diameter and stable aerodynamics, despite moderate manufacturing tolerances, blade-opening arrowheads were designed. Blade-opening arrowheads differ from conventional fixed-blade arrowheads in that the cutting blades are folded up or held adjacent to the arrowhead body in a retracted position while the arrow is in flight, but at impact with the game animal rotate or pivot into an open position, therefore exposing the sharp blade edges and cutting the animal. Since the blades of blade-opening arrowheads are held adjacent to the arrowhead body and do not extend very far out from it, any aligning or centering problems of a blade-opening arrowhead attached to an arrow will not noticeably steer the arrow or undesirably affect its flight trajectory. In this manner blade-opening arrowheads can have both a desirable large cutting diameter, and the stable arrow flight characteristics necessary for accurate shot placement. Blade-opening arrowheads can therefore potentially be more lethal. 
     Blade-opening arrowheads like conventional fixed blade arrowheads generally have an elongated arrowhead body, a tip end, and a threaded opposite end. The blades of blade-opening arrowheads have an attachment end which attaches the blades to the arrowhead body by a pivot pin, so that the blades can pivot or rotate between the retracted position and the open position. Blade-opening arrowheads also come in a variety of different types and styles. The blades of the most common type of blade-opening arrowheads, when in the retracted position have a leading blade end positioned near the tip of the arrowhead that protrudes outward from the arrowhead body, and is some times shaped like a wing. The leading blade ends of the most common type of blade-opening arrowheads, rotate away from the arrowhead body in a rearward direction when penetrating an animal. Particularly, the leading blade ends catch on the animal&#39;s surface and serve to lever or rotate the blades into the open position. The blades of blade-opening arrowheads are also received in blade slots, which are machined or formed into the side of the arrowhead body. 
     Blade-opening arrowheads for hunting big game must be non-barbing, wherein the blades when in the open position must not inhibit or prevent arrow extraction from a game animal by barbing into the animal tissue. This makes it so non-fatally wounded animals can easily pull out an arrow still lodged in them. For an arrowhead to be non-barbing, the pivotal blades must rotate from the open position to an angle greater than ninety degrees, as measured between the rear edge of each blade and a location on the arrow shaft rearward of the blades. 
     Blade-opening arrowheads generally do not penetrate as deep as conventional fixed-blade arrowheads. Sometimes in hunting situations an arrow will not completely pass through the game animal and will not have sufficiently cut any vital organs or vascular vessels, and thus not having inflicted a lethal wound. Sometimes in these instances the arrowhead will have penetrated within the game animal near an artery or vital organ such that as the animal retreats, the arrowhead continues to cut as it moves within the animal, and the artery or vital organ is severed, and the animal is harvested. Conventional blade-opening arrowheads are generally not as lethal in these types of situations, as arrowheads having the cutting blades positioned near the tip of the arrowhead, such as conventional fixed-blade arrowheads. This is because the cutting blades of the most popular types of conventional blade-opening arrowheads when in the open position, are positioned approximately one and a half inches back from the arrowhead tip, and therefore cut a lesser volume of tissue despite equal arrowhead penetration depth. 
     To hold the blades of blade-opening arrowheads in the retracted position during flight until the arrowhead penetrates the animal, annular retention members such as O-rings are most commonly used. Other commonly known annular retention members are, rubber bands, tight fitting plastic sleeves, tape, heat-shrinkable fitting plastic sleeves, and other wrap materials. When the O-rings are stretched around the outside of the blades they exert a resistive force against the blades and hold the blades selectively in the retracted position. 
     O-ring use for blade retention is less than ideal. The elastomeric polymer materials are susceptible to drying-out and therefore cracking, which can lead to breaking of the O-ring during arrow acceleration when the arrow is shot. This will cause premature blade-opening and produce extremely erratic arrow flight and possible non-lethal wounding of the game animal. This may also cause severe lacerations to the archer. Also, bows shooting arrows at very high speeds can require as many as three O-rings to prevent premature blade-opening. The experience of learning this can be very undesirable for the archer. O-rings are a consumable item designed for one shot use, and the cost of constantly replacing them is a detrimental factor. Also, they are not user-friendly and are a general bother to worry about while out in the field. 
     Aside from consumer use considerations, humaneness to the hunted game animal is an important consideration as well. When the arrowhead penetrates the animal and the blades begin to rotate open, the more the O-ring is stretched the more resistive force it exerts back against the blades, thus impeding the rate of blade-opening. This can possibly prevent full blade-opening and a quick and humane kill. Also, extreme weather temperatures greatly affect the elasticity of O-rings; cold weather decreases elasticity which increases the likelihood of the blades not opening, and hot weather increases elasticity which increases the likelihood of premature blade opening. 
     Attempts in the prior art have been made to remedy the problems associated with O-ring use for blade retention of blade-opening arrowheads, but these attempts have their own problems as well. For example, the use of magnetism for blade retention is known to the art. The disadvantages of using magnets for blade retention are that magnets are heavy, relatively expensive, and can demagnetize. The use of a leaf spring for blade retention is also known to the art, where the leaf spring is positioned and held in the blade slot by a set-screw, which is usually also the pivot pin. One disadvantage of using a leaf spring for blade retention is the difficulty involved when replacing the blades; having to simultaneously line up a hole in the leaf spring, a hole in the blade, and a hole in the arrowhead body while inserting a set screw through all three members, for each blade. Another disadvantage of using a leaf spring for blade retention is limitations of the leaf spring, where a very small amount of dirt, debris or ice can prevent the leaf spring from deflecting, and also, the flexibility life span of the leaf spring can be short. This could possibly inhibit blade-opening altogether. Disadvantages of other blade retention methods known to the art are, reduced penetration of the arrowhead, structural weakening of various arrowhead elements, in-operability, and manufactural unfeasibleness. 
     It is apparent that there are much needed improvements in blade-opening arrowheads, both in consideration of the archery consumer and the hunted game animal. 
     It is apparent that there is a need for a blade-opening arrowhead that securely holds each blade selectively in a retracted or in-flight position, in a secure or locked manner, by methods other than O-rings or similar consumable elements, that is user-friendly, manufacturally feasible, and structurally strong. 
     It is also apparent that there is a need for a blade-opening arrowhead that securely holds each blade selectively in a retracted or in-flight position, in a secure or locked manner, that is operable and is not suspectable to malfunctioning by contamination of dirt, debris, or ice and/or by short life span of the blade retention method. 
     It is yet further apparent that there is a need for a blade-opening arrowhead that is capable of driving the razor cutting edges of the blades from the open position, forwardly into uncut or unpenetrated tissue of an arrowed game animal when the arrow is lodged in the animal, especially when the animal has not been fatally or lethally hit, thus to increase the lethality of the arrowhead, and to be more humane to the animal. 
     SUMMARY OF THE INVENTION 
     It is one object of the present invention to provide blade-opening arrowheads with blade retention methods that do not require the use of consumable annular members such as O-rings. 
     It is another object of the present invention to provide a blade-opening arrowhead that securely holds each blade selectively in a retracted in-flight position, in a secure or locked manner by methods other than O-rings or similar elements, that is user-friendly, manufacturally simple, and structurally strong. 
     It is another object of the present invention to provide a blade-opening arrowhead that securely holds each blade selectively in a retracted in-flight position, in a secure or locked manner that is operable and is not suspectable to malfunctioning, especially by contamination of dirt, debris, ice and/or by short life span of the blade retention method. 
     It is another object of the present invention to provide a blade-opening arrowhead that securely holds each blade selectively in a retracted or in-flight position, in a secure or locked manner by releasably latching the blade edge of each blade to the arrowhead body or equivalent. Specifically where an urging force urges the blades in a forward direction to securely hold the edge of each blade engaged against the arrowhead body, and therefore the blades are securely held adjacent to the arrowhead body when in a retracted position but freely rotate into an open position when the arrowhead penetrates an object. 
     It is still another object of the present invention to provide a blade-opening arrowhead that securely holds each blade selectively in a retracted or in-flight position, in a secure or locked manner by releasably latching the blade edge of each blade to a holding element. Specifically where an urging force urges the holding element to securely hold the edge of each blade engaged against the holding element, and therefore the blades are securely held adjacent to the arrowhead body when in a retracted position but freely rotate into an open position when the arrowhead penetrates an object. 
     It is yet further another object of the present invention to provide a blade-opening arrowhead that is capable of driving or continually urging the razor cutting edge of each blade from the open position, forwardly into uncut or unpenetrated tissue of an arrowed game animal. 
     The foregoing objects and advantages and other objects and advantages of the present invention are accomplished with a hunting arrowhead that attaches to the forward end of an arrow shaft, where a plurality of blades are pivotally connected to an arrowhead body. The blades freely rotate from an in-flight retracted position to an open position when the arrowhead penetrates an object, or when acted upon by a sufficient opening force. When the blades are in the in-flight retracted position they are securely held selectively adjacent to the arrowhead body by engagement of a blade edge of each blade to a holding element. 
     Such a blade-opening arrowhead according to one preferred embodiment of this invention has an arrowhead body with a tip end used for initial penetration and an opposing threaded shaft end that screws or threads the arrowhead to an arrow. The tip end may be removably attached to the arrowhead body, and may be made of material different than the rest of the arrowhead body. The arrowhead body has a plurality of blade slots, one for each respective blade. Each blade has a first end, an opposing second end and an edge extending about its periphery. One blade edge of each blade is sharpened for cutting. The first blade ends or the leading ends each have a protruding wing that is exposed out from the arrowhead body when the blades are in the retracted position. The wings serve to increase the moment-arm for levering or rotating the blades to the open position. The second end of each blade has an aperture or hinge pin receiving hole for receiving a pivot pin or a hinge pin. The arrowhead body also has a hinge pin receiving hole for each blade. The arrowhead body hinge pin receiving holes are recessed or drilled into the two opposing sidewalls of each blade slot, and are threaded to receive the threaded hinge pins. A single hinge pin is used for each blade, and when the blades are positioned in the blade slots, each hinge pin is extended through the aperture of a corresponding blade and is screwed into the arrowhead body. This pivotally connects the blades to the arrowhead body. The cross-sectional area or open area of each blade aperture is greater than the cross-sectional area of its corresponding hinge pin, such that a gap is created between each hinge pin and blade aperture of each blade, when the hinge pins are extended through the blade apertures. These gaps allow each blade to freely move in a forward and rearward direction independent of the arrowhead body and corresponding hinge pin. The blade edge of the first end of each blade has a catch lip or a bump protruding out from it near the cutting edge. The arrowhead body has one receiving notch or holding element formed in it for each blade. The notches are situated near the top of each blade slot and are recessed into the arrowhead body. An annular recess encircling the arrowhead body is situated below the blade slots, and is recessed into the arrowhead body. This annular recess communicates with each blade slot and leaves or defines a stem shaped portion on the arrowhead body. An annular compression spring or coil spring is positioned in the annular recess, with a separate annular ring positioned forward or above the annular spring. Both the annular ring and annular spring are slidably positioned around the stem portion of the arrowhead body, such that the annular ring contacts the second end of each blade. An annular blade-stop washer shaped like a doughnut, also having a recessed portion shaped to contain the annular spring, is slidably positioned around the arrowhead body stem below the annular spring, and contacts the rear end of the annular spring. The blade-stop washer has a sloped outer and upper side, that serves to abut against the blades when they are rotated to the fully open position, thus defining the cutting diameter of the arrowhead when the blades are in the fully open position. 
     When a blade-opening arrowhead according to the preferred embodiment of this invention as described above, is tightly fastened to the forward end of an arrow shaft, the blade-stop washer is tightened-up against both the arrow shaft and the arrowhead body. This tightening causes the annular spring to be compressed between the blade-stop washer and the annular ring. This compression or biasing of the spring causes an urging force to be exerted against the second ends of the blades in a generally axial direction. The annular ring serves to transfer the urging force equally to all blades. Since a gap exists between each hinge pin and each blade aperture, the urging force moves the blades forward relative to the arrowhead body, and engages or receives the catch lips on the blades into their corresponding receiving notches in the arrowhead body. The continual compression of the annular spring provides a continual urging force which maintains the engagement of the catch lips and notches, thus releasably latching and securely holding the blades selectively in the retracted position. The urging force is strong enough to maintain the blades in the retracted position when the arrow is exposed to incidental forces, such as those produced from transporting the bow, nocking an arrow to the bow string, and acceleration when the arrow is shot. The urging force is weak enough however, to be easily overcome when the arrow impacts or begins to penetrate a game animal. 
     When the arrowhead according to the above described preferred embodiment initially penetrates an animal, the first ends or leading ends of the blades catch on the animal&#39;s surface and the blades are driven rearwards which unlatches the blades. At initial penetration the annular spring is then compressed such that the catch lips are disengaged from the notches sufficiently that the blades lever-out and freely rotate towards the open position. With the blades in the open position, the urging force of the annular spring continually urges the cutting edges of each blade in a forward direction, providing the ability to further cut additional animal tissue, should the arrow still be lodged in the animal. 
     All that is required to securely lock the blades back in the retracted position, is to simply push each blade back into the retracted position, and the spring compresses as the catch lips are received back into the notches. Once the catch lips are received into the notches, the continual urging force of the spring simply maintains the blades in the retracted position again. Also, when the sharp edges of the blades become dull, all that is required to change the blades is to un-compress the spring by slightly unscrewing the arrowhead from the arrow shaft, and then remove the threaded hinge pin, insert a new blade, and re-insert the hinge pin. There is no requirement to spend additional time and effort lining up tiny holes in other tiny elements such as a leaf spring, with the blade aperture and arrowhead body pivot pin receiving hole, when changing blades or when replacing the spring element or elements. 
     Blade-opening arrowheads according to other preferred embodiments of this invention differ from the above described preferred embodiment in that they have an annular hinge pin, where the plurality of blades are all attached to the single annular hinge pin. The annular hinge pin is slidably positioned on the stem located near the rear end of the arrowhead body, and is received in the same annular recess as the annular spring and annular ring. According to one such annular hinge pin embodiment, there is substantially no gap between the hinge pin and each blade aperture, and the blades and hinge pin are both urged or moved forward together by the annular spring when the catch lips are received or engaged into the notches. In another annular hinge pin preferred embodiment according to this invention, a gap is formed between the hinge pin and each blade aperture, and the blades are urged or biased by the annular spring when the catch lips are received into the notches. 
     A blade-opening arrowhead according to another preferred embodiment of this invention, also has an annular recess encircling the arrowhead body, situated below the blade slots, which defines a stem shaped portion on the arrowhead body, and which houses an annular spring and an annular ring. The blade-opening arrowhead according to this preferred embodiment has a catch lip and an adjacent notch in the second end of each blade. Each notch is positioned medial to its corresponding catch lip when the blades are in the retracted position. Each notch is defined by its corresponding catch lip, wherein the notches were created by removal of blade material in fabricating the protruding catch lips. The annular spring urges the annular ring against each catch lip and into each notch, thus engaging the blade edges at the second end of each blade, and securely holding the blades selectively adjacent to the arrowhead body when in the retracted position. The blades are prevented from rotating outwards prematurely by the lateral or outside edge of each blade notch abutting against the lateral surface of the annular ring. When the blade-opening arrowhead according to this preferred embodiment impacts a game animal and the blades begin rotating outwards, the catch lips or lateral edges of the notches are driven into the annular ring, which compresses the annular spring such that the tip of each catch lip slips over the annular ring, thus disengaging the annular ring from the notches and thus allowing the blades to freely rotate towards the open position. 
     According to another preferred embodiment of this invention, an annular spring is positioned in an annular recess situated near the forward end of the arrowhead body within a separably attachable tip piece. The blade-opening arrowhead according to this preferred embodiment has a catch lip and an adjacent notch in the first end of each blade. Each notch is positioned lateral to its corresponding catch lip when the blades are in the retracted position. Also the notch and catch lip of each blade are situated near the cutting edges of the blades. Each notch is defined by its corresponding catch lip, wherein the notches were created by removal of blade material in fabricating the protruding catch lips. The annular spring urges the annular ring against each catch lip and into each notch in a rearward generally axial direction, thus latching the blade edges and securely holding the blades selectively adjacent to the arrowhead body in the retracted position. The blades are prevented from rotating outwards prematurely by the medial or inside edge of the blade notches abutting against the medial surface of the annular ring. When the arrowhead impacts an animal and the blades begin to rotate outwards, the catch lips are driven into the annular ring, which forces the annular spring to compress until the catch lips freely slip under the annular ring. In this manner the blades are unlatched and freely rotate towards the open position. 
     The blade-opening arrowheads according to this invention, use no consumable items such as O-rings, for blade retention. The blade retention methods of the blade-opening arrowheads according to this invention, are simple and user-friendly. The blade-opening arrowheads according to this invention provide blade retention methods that are not suspectable to malfunctioning when exposed to the harsh conditions commonly encountered in the field, and when subjected to prolonged use. Should ice, dirt or debris get intermingled with the annular spring of the type preferred for use according to this invention, the annular spring will still serve to produce an effective blade retention urging force, and to allow the timely opening of the blades at target impact. This is so because the spaces between the spring coil wires are large enough to handle a relatively large accumulation of foreign matter, yet have room to allow adequate spring compressing. Also, the length of spring flexibility life of the annular spring according to this invention, under normal use considerations, is indefinite. This is such because the diameter or gauge of the wire, and the general diameter of the spring are large enough that the annular spring is extremely rugged and durable in nature, especially when compared to the relatively light work load required of it. 
     The blade-opening arrowheads according to this invention are also more humane, and more lethal than prior art arrowheads. Should the arrow become lodged in the game animal, particularly when the animal has not been fatally hit, the blades will be driven or continually urged in a forward direction by the urging force of the annular spring, cutting additional tissue, which could possibly sever any nearby arteries or vital organs, and thus decrease the wounding loss. This trait of cutting additional tissue is a feature that no prior arrowhead performs. The blade-opening arrowheads, according to this invention are also structurally strong, simple and feasible to manufacture, and operable. 
     As has been shown in the above discussion, the blade-opening arrowheads according to this invention overcome deficiencies inherent in prior art arrowheads. 
    
    
     With the above objects and advantages in view, other objects and advantages of the invention will more readily appear as the nature of the invention is better understood, the invention is comprised in the novel construction, combination and assembly of parts hereinafter more fully described, illustrated, and claimed. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is perspective view of an arrow with a blade-opening arrowhead according to one preferred embodiment of this invention attached to the forward end of the arrow shaft, with the blades in the retracted position; 
     FIG. 2 is a full length longitudinal cross-section of the preferred embodiment as illustrated in FIG. 1, but showing a plurality of two blades pivotally connected to the arrowhead body, with the blades in the retracted position. The annular ring and annular spring are shown in perspective view; 
     FIG. 3 is a full length longitudinal cross-section of a blade-opening arrowhead as illustrated in FIG. 2, showing initial rearward blade displacement occurring at initial penetration of an object; 
     FIG. 4 is a full length longitudinal cross-section of a blade-opening arrowhead as illustrated in FIG. 2, showing the blades rotating away from the arrowhead body after initial penetration of an object; 
     FIG. 5 is a full length longitudinal cross-section of a blade-opening arrowhead as illustrated in FIG. 2, showing the blades in the fully open position with the annular spring continually urging the blades forward; 
     FIG. 6 is an exploded full length longitudinal cross-section of a blade-opening arrowhead as illustrated in FIG.  2 . The hinge pins, annular ring, annular spring and blades are shown in perspective; 
     FIG. 7 is a full length longitudinal cross-section of a blade-opening arrowhead according to another preferred embodiment of this invention, similar to the preferred embodiment shown in FIG. 2, but without an annular ring; 
     FIG. 8 is a full length longitudinal cross-section of a blade-opening arrowhead according to another preferred embodiment of this invention, showing the annular spring urging the annular ring into a notch in each blade. The hinge pins, annular ring, annular spring and blades are shown in perspective. An additional detached blade is shown also; 
     FIG. 9 is a full length longitudinal cross-section of a blade-opening arrowhead according to another preferred embodiment of this invention, showing an annular hinge pin slidably positioned on the arrowhead body, with substantially no gap between the blade apertures and annular hinge pin. The annular hinge pin is shown in a top view also; 
     FIG. 10 is a full length longitudinal cross-section of a blade-opening arrowhead similar to the blade-opening arrowhead illustrated in FIG. 9, but without an annular ring. The annular hinge pin is shown in a top view also; 
     FIG. 11 is a full length longitudinal cross-section of a blade-opening arrowhead according to another preferred embodiment of this invention, similar to the preferred embodiment illustrated in FIG. 9, except a gap is formed between the blade apertures and hinge pin. The annular hinge pin is shown in a top view also; 
     FIG. 12 is a full length longitudinal cross-section of a blade-opening arrowhead similar to the blade-opening arrowhead illustrated in FIG. 11, but without an annular ring. The annular hinge pin is shown in a top view also; 
     FIG. 13 is a full length longitudinal cross-section of a blade-opening arrowhead according to another preferred embodiment of this invention, showing a plurality of blades pivotally connected to the arrowhead body, with the blades in the retracted position. The annular ring and annular spring are shown in perspective; 
     FIG. 14 is a full length longitudinal cross-section of a blade-opening arrowhead according another preferred embodiment of this invention, similar to the preferred embodiment shown in FIG. 13, showing a plurality of blades pivotally connected to the arrowhead body, with the blades in the retracted position, but without an annular ring; and 
     FIG. 15 is an exploded full length longitudinal cross-section of a blade-opening arrowhead as illustrated in FIG.  13 . The hinge pins, annular ring, annular spring and blades are shown in perspective. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 REFERENCE NUMERALS IN DRAWINGS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 16 
                 arrow 
               
               
                   
                 17 
                 nock 
               
               
                   
                 18 
                 arrow shaft 
               
               
                   
                 19 
                 fletching 
               
               
                   
                 20 
                 blade-opening arrowhead 
               
               
                   
                 21 
                 blade-opening arrowhead 
               
               
                   
                 22 
                 blade-opening arrowhead 
               
               
                   
                 23 
                 blade-opening arrowhead 
               
               
                   
                 24 
                 blade-opening arrowhead 
               
               
                   
                 25 
                 blade-opening arrowhead 
               
               
                   
                 26 
                 blade-opening arrowhead 
               
               
                   
                 27 
                 blade-opening arrowhead 
               
               
                   
                 28 
                 blade-opening arrowhead 
               
               
                   
                 30 
                 arrowhead body 
               
               
                   
                 32 
                 tip 
               
               
                   
                 34 
                 stem 
               
               
                   
                 36 
                 blade-stop washer 
               
               
                   
                 38 
                 hinge pin receiving hole, 
               
               
                   
                   
                 arrowhead body 
               
               
                   
                 40 
                 notch, arrowhead body 
               
               
                   
                 42 
                 sidewall of arrowhead body 
               
               
                   
                 44 
                 notch, blade 
               
               
                   
                 46 
                 second notch, blade 
               
               
                   
                 50 
                 blade 
               
               
                   
                 52 
                 aperture 
               
               
                   
                 54 
                 inner edge, cutting edge 
               
               
                   
                 56 
                 outer edge 
               
               
                   
                 58 
                 distal edge 
               
               
                   
                 60 
                 catch lip 
               
               
                   
                 62 
                 proximal edge 
               
               
                   
                 64 
                 wing 
               
               
                   
                 66 
                 side of blade 
               
               
                   
                 68 
                 blade slot 
               
               
                   
                 70 
                 hinge pin 
               
               
                   
                 72 
                 annular recess, arrowhead body 
               
               
                   
                 74 
                 annular recess, blade-stop 
               
               
                   
                   
                 washer 
               
               
                   
                 76 
                 annular recess, tip 
               
               
                   
                 78 
                 abutting shoulder, arrowhead 
               
               
                   
                   
                 body 
               
               
                   
                 80 
                 annular spring 
               
               
                   
                 82 
                 annular ring 
               
               
                   
                 84 
                 annular hinge pin 
               
               
                   
                 90 
                 gap 
               
               
                   
                 100 
                 opening force 
               
               
                   
                   
               
             
          
         
       
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1-6 illustrate a preferred embodiment according to this invention wherein FIG. 1 shows a conventional arrow  16 , having a nock  17  for receiving a bow string, an arrow shaft  18 , stabilizing fletchings  19 , and a blade-opening arrowhead  20  attached to the forward end of the arrow shaft  18 . The stabilizing fletchings  19  are helically mounted on the arrow shaft  18 , which causes the arrow  16  to spiral or rotate in flight, which greatly enhances accuracy. Blade-opening arrowhead  20 , in FIG. 1, shows a plurality of three blades  50  pivotally connected to an arrowhead body  30 , each by a hinge pin  70  that is threaded or screwed into a corresponding threaded hinge pin receiving hole  38  in arrowhead body  30 . Hinge pin receiving hole  38  passes through the opposing sidewalls of a corresponding blade slot  68 , for each blade  50 . An aperture  52  in one opposing end of each blade  50  has hinge pin  70  extending therethrough, when blades  50  are pivotally connected to arrowhead body  30 . Each blade  50  rotates between a retracted position where the edges of blades  50  are engaged and releasably latched to holding means, as shown in FIGS. 1 and 2, and an open position as shown in FIG. 5 where the other opposing blade end of each blade  50  is rotated away from arrowhead body  30 . A gap  90  is formed between each hinge pin  70  and aperture  52 , such that each blade  50  is free to move relative to corresponding hinge pin  70  and arrowhead body  30 . Hinge means connect each blade  50  to arrowhead body  30 . 
     Hinge means, according to this invention, are intended to comprise any suitable element or elements that serve to pivotally connect each blade  50  to arrowhead body  30 . As shown in FIGS. 1-8 and  13 - 15  according to some preferred embodiments of this invention, straight hinge pins  70  are received in apertures  52  located near a second blade end or a proximal blade edge  62 , of each corresponding blade  50 . As shown in FIGS. 9-12 according to other preferred embodiments of this invention, annular hinge pin  84  is received in apertures  52  of a corresponding plurality of blades  50 , near the second end of each blade or proximal blade edges  62 . Any shape of aperture  52  and any pin  70 ,  84 , received therein will suffice for hinge means. Hinge means may comprise rod or bar stock, bearing members such as a ball bearing, and protrusions or bumps machined or formed into the arrowhead bodies  30 , and the like, and may be straight or curved such as annularly, and may accommodate, have connected thereto or have received thereon a plurality of blades  50 , or a single individual blade  50 . The hinge means according to this invention may attach to the arrowhead body  30  slidably, or be screwed or threaded on. It is apparent that apertures  52  may not communicate with the peripheral edges of blades  50  thereabout, thus creating a through hole, or that apertures  52  may communicate with the peripheral edges of blades  50 . 
     Referring to FIGS. 1-6, wherein FIG. 2 shows a blade-opening arrowhead  20 , identical to blade-opening arrowhead  20  as illustrated in FIG. 1, but for reasons of clarity having only two blades  50 , which are superimposed upon a longitudinal cross-section or cutaway of arrowhead body  30 . Each blade  50  has a pair of blade sides  66 , and is positioned in a respective blade slot  68  that communicates with an outer sidewall  42  of arrowhead body  30 . An annular spring  80  and an annular ring  82  shown in perspective view in FIG. 2, are positioned slidably about a stem  34  of arrowhead body  30 . Annular spring  80  and annular ring  82  are positioned in an annular recess  74  of a blade-stop washer  36  and an annular recess  72  of arrowhead body  30 . Both annular recesses  72 ,  74  encircle about the longitudinal axis of blade-opening arrowhead  20 . Each blade  50  when in the retracted position has an inner edge  54  extending generally longitudinally between opposing blade ends, and an outer edge  56  extending generally longitudinally between opposing blade ends. Also, a distal edge  58  extends between inner edge  54  and outer edge  56  at the first end or leading ends of blades  50 , and a proximal edge  62  extends between inner edge  54  and outer edge  56 , at the second end or hinge connecting ends of blades  50 . 
     Blade-stop means, such as blade-stop washer  36 , according to this invention, serve to abut outer edge  56  of each blade  50  when blades  50  are in the fully open position as illustrated in FIG. 5, thus defining the cutting diameter of arrowhead  20 . Blade-stop means according to this invention comprise any element that serves to abut against blades  50 , thus stopping their opening rotation. It is apparent that outer blade edges  56  may abut arrowhead body  30  or an equivalent, to lessen the impact forces transferred to the hinge means. 
     Selectively retaining blades  50  in a retracted or in-flight position according to this invention is intended to mean that the position blades  50  are placed in is selectable, or that blades  50  can be positioned in more than one position. Preferably selectable blade positions according to this invention are the retracted position and the open position. Blades  50  are securely held in the retracted position or in a first selectable position in a locked manner until acted upon by an opening force  100 , whereupon they freely rotate to the open position, or a second selectable position. 
     According to the preferred embodiment illustrated in FIGS. 1-6, annular ring  82  is biased into or against proximal edges  62  of each blade  50  when annular spring  80  is compressed. When arrowhead  20  is tightly fastened to arrow shaft  18 , blade stop washer  36  is snugged up to both arrowhead body  30  and to arrow shaft  18 . This compresses annular spring  80  such that annular spring  80  biases annular ring  82  into blades  50 . The forward displacement of annular ring  82  and annular spring  80  is limited by an abutting shoulder  78 , as shown in FIG.  6 . This biasing or compressing of annular spring  80  produces an urging force which urges blades  50  in a forward direction such that a catch lip  60  on distal blade edge  58  of each blade  50  is received or engaged in a corresponding receiving notch  40 . Notches  40  are recessed into arrowhead body  30  near the forward end of each corresponding blade slot  68 . When catch lips  60  are received into notches  40  the edges of blades  50  are releasably latched and engaged such that blades  50  are securely held selectively adjacent to arrowhead body  30  in the retracted position. When arrow  16  having blades  50  in the retracted position, as shown in FIG. 1, is shot and impacts an animal or an object, and begins initial penetration, as shown in FIG. 3, a wing  64  projecting out from blade edges  56  and  58  of each blade, catches on the animal&#39;s surface and opening force  100  drives blades  50  rearwardly. As is clearly shown in FIG. 3 at initial penetration or impact, annular spring  80  is compressed, such that gaps  90  are below hinge pins  70 , and catch lips  60  are effectively disengaged from notches  40  so that blades  50  are unlatched. As shown in FIG. 4, while penetrating the animal or object after initial impact, blades  50  begin to rotate away from arrowhead body  30 , towards the fully open position. As illustrated in FIG. 5, when blades  50  are in the open position the continual urging force produced by annular spring  80  drives or continually urges cutting edge  54  of each blade  50  in a forward direction, further slicing uncut or unpenetrated tissue. When arrowhead  20  is pulled-out from a target or a game animal blades  50  rotate from the fully open position to a non-barbing position as clearly shown in FIG. 4, wherein the angle between blade edges  56  of each blade and a point rearward of hinge pins  70  on arrow shaft  18  is greater than ninety degrees. It is apparent that wing  64  can be positioned at different locations along blade edge  56  of each blade  50 , specifically to create an open-after impact blade-opening arrowhead, as is known to the art. 
     Bias means according to this invention, comprise any element or elements that produce an urging force. Bias means according to this invention can comprise, but not be limited to, any resilient, compressible, deflectable, flexible, or stretchable mechanical member or members and the like, which have the ability to substantially return to their original state, such that an urging force is generated in a direction substantially opposite the direction the bias element or bias means is deformed. Bias means may include a single bias element urging a plurality of blades, or may be an individual bias element for each blade, or a combination thereof. Bias means for example, can include, cantilevers, rubber material, certain hydraulic systems and/or filled bladder systems, and springs such as compression, coil or leaf. The bias means can be fabricated of metal, plastics or composites. In the preferred embodiments according to this invention, bias means produce an urging force which is preferably strong enough to securely hold the pivotal blades  50  retained in the retracted position when exposed to incidental forces, but yet is weak enough to be quickly and immediately overcome when penetrating an object, such that razor cutting edges  54  are timely exposed, and the penetrated object is maximumly cut. According to this invention compressible annular spring  80  mounted on arrowhead body  30  to bias against the edges of blades  50  when blades  50  are in the retracted position, may include or mean that annular spring is biasing an element into the edges of blades  50  other than itself, such as annular ring  82 . 
     Means for continually urging cutting edges  54  of the blades  50  forward when in the open position may comprise the bias means according to this invention. 
     FIG. 7 illustrates blade-opening arrowhead  21 , another preferred embodiment according to this invention. Blade-opening arrowhead  21  is similar to blade opening arrowhead  20  except annular ring  82  is omitted. It is apparent that the operation of blade retention according to the scope of this invention is attainable without use of annular rings or equivalents, such as annular ring  82 . 
     FIG. 8 illustrates blade-opening arrowhead  22 , another preferred embodiment according to this invention which is similar to blade-opening arrowheads  20  and  21 , except blade-opening arrowhead  22  has no receiving notches in arrowhead body  30 , but rather has a notch  44  and adjacent catch lip  60  in proximal edges  62  of each blade  50 . As is clearly illustrated in FIG. 8, when blades  50  are in the retracted position catch lips  60  are positioned immediately lateral of notches  44 . To securely hold blades  50  of arrowhead  22  selectively adjacent to arrowhead body  30  in the retracted position, the urging force produced by annular spring  80  urges annular ring  82  into notches  44  and against catch lips  60  of each blade  50 . This engages each edge of blades  50  to annular ring  82 , which prevents blades  50  from rotating towards the open position prematurely or until acted upon by a sufficient opening force  100 . When arrowhead  22  is shot and impacts an animal, and begins initial penetration, wings  64  projecting out from blade edges  56  and  58  of each blade, catch on the animal&#39;s surface and opening force  100  drives blades  50  rearwardly, thus disengaging blade edges  62  and allowing blades  50  to freely rotate to the open position. It is apparent that another notch  46  can be situated in outer edge  56  of each blade near apertures  52 , such that when blades  50  are in the fully open position annular ring  82  is matingly received or engaged in such other notches. It is also apparent that annular ring  82  or annular spring  80  can contact blade edges  62  of each blade, medially of, in line with, or lateral of, the cross-sectional center of corresponding hinge pins  70 . According to this invention catch lips  60  of each blade  50  comprise a protruding point or tip and inclined sides, so that when annular spring  80  urges annular ring  82  against catch lips  60  of each blade  50  or when annular spring  80  is biased against catch lips  60 , the sides of catch lips  60  are contacting the bias means and/or holding means. 
     Holding means according to this invention comprise any surface or surfaces, whether integral with, or separably attachable from, arrowhead body  30 , which are capable of being in contact with a specific area or areas of the edge of each blade, to engage with such blade edge areas such that blades  50  are securely held selectively adjacent to arrowhead body  30  when blades  50  are in the retracted position. Holding means according to this invention may also comprise the blade edge or specific areas of the blade edge, in addition to the surfaces that contact the blade edges as discussed above. For example, holding means may comprise catch lips  60  and notches  40 . 
     According to the preferred embodiments of this invention retaining means comprise bias means and holding means, where an urging force produced from the bias means engages the holding means to the edge of each blade  50 , such that each blade  50  is securely held selectively adjacent to arrowhead body  30  when in the retracted position. 
     According to this invention engagement, or engaging and disengaging, of a blade edge to holding means has the intended meaning that when blades  50  are held in the retracted position the engaging areas of the blade edges are engaged with the holding means such that they are in contiguous or intimate contact with the holding means, and then when blades  50  are acted upon by a sufficient opening force  100  the specific engaging areas of the blade edges are disengaged such that they are no longer in contiguous or intimate contact with the holding means. 
     Releasably latching, or latching and unlatching, of a blade edge to holding means according to this invention, as used throughout this specification and in the claims, has the intended meaning that substantially no part of the blade edge of each blade is in contact with the holding means after disengagement of the holding means from the specific blade edge engaging area or areas. Contrastingly, O-rings and the like, remain in contact with the blade edges for a significant portion of the blade rotation while the blades are rotating towards the open position, wherein the more the blades rotate towards the open position the more the O-ring is stretched and further stretched, thus impeding the rate of blade opening, until the O-ring is sheared or rolls back. 
     According to the preferred embodiments of this invention the blade edges are engaged and disengaged to holding means. According to some preferred embodiments of this invention the blade edges are also releasably latched in addition to being engaged and disengaged, whereas in other preferred embodiments of this invention the blade edges are not releasably latched when the blades edges are engaged and disengaged. It is apparent that engaging and disengaging, and releasably latching according to this invention can be interchanged, and/or combined amongst the preferred embodiments of this invention in various different arrangements, without deterring from the scope of the invention. 
     In the preferred embodiment of this invention as illustrated in FIG. 8, retaining means comprise holding means and bias means, where bias means urge holding means into notches  44  and against catch lips  60  of edges  62  of each blade  50 , to securely hold edges  62  of blades  50  engaged against the holding means. Particularly, the holding means comprises annular ring  82 , and the bias means comprises annular spring  80  which urges annular ring  82  into notches  44  of each blade  50 . 
     Retaining means according to the preferred embodiments of this invention as illustrated in FIGS. 1-7 and  9 - 15 , releasably latch the edge of each blade  50  such that blades  50  are selectively held in a retracted position until penetrating an object or when subjected to opening force  100 , whereupon blades  50  are unlatched, and freely rotate towards the fully open position. 
     According to the preferred embodiments of this invention as illustrated in FIGS. 1-7, and  9 - 12 , retaining means comprise holding means and bias means, where the bias means urge blades  50  into the holding means, to securely hold the edges of blades  50  engaged and latched against the holding means. Particularly, the holding means comprises receiving notches  40  and the bias means comprises annular spring  80  which urges catch lips  60  into notches  40 . 
     In the preferred embodiments of this invention as illustrated FIGS. 13-15, retaining means comprise holding means and bias means, where bias means urge holding means into and against edges  58  of each blade  50 , to securely hold edges  58  of blades  50  engaged and latched against the holding means. Particularly, the holding means comprises annular ring  82 , and the bias means comprises annular spring  80  which urges annular ring  82  into notches  44  of each blade  50 . 
     FIGS. 13 and 15 illustrate a blade-opening arrowhead  27  according to another preferred embodiment of this invention, where annular spring  80  and annular ring  82  are housed in an annular recess  76  situated within removably attachable tip piece  32 , and annular recess  72  which is positioned near the forward end of arrowhead body  30 . Particularly, according to blade-opening arrowhead  27  bias means comprises compressible annular spring  80  biasing annular ring  82  against distal edge  58  of each blade  50 , and holding means comprises annular ring  82 . Blade-opening arrowhead  27  has substantially no gap between apertures  52  and hinge pins  70 . 
     FIG. 14 illustrates a blade-opening arrowhead  28  according to another preferred embodiment of this invention, similar to arrowhead  27 , except without an annular ring. Particularly, according to blade-opening arrowhead  28  as shown in FIG. 14, bias means comprises compressible annular spring  80  biased against distal edge  58 , of the first end of each blade  50 , and holding means also comprises annular spring  80 . Accordingly, holding means comprises bias means. When annular spring  80  is urged into notches  44  and against catch lips  60  of distal edge  58  of each blade  50 , blades  50  are engaged and latched in the retracted position. 
     FIGS. 9-12 illustrate blade-opening arrowheads  23 - 26  according to this invention, which are similar to blade-opening arrowheads  20  and  21  as illustrated in FIGS. 1-7, except annular hinge pin  84  receives the plurality of blades  50  for each arrowhead  23 - 26 . Annular hinge pin  84  is slidably positioned in annular recess  72  around stem  34  of arrowhead body  30 . 
     FIGS. 9 and 10 illustrate blade-opening arrowheads  23  and  24  which have substantially no gap between apertures  52  of blades  50  and annular hinge pin  84 , wherein both the plurality of blades  50  and annular hinge pin  84  are urged together when engaging or receiving catch lips  60  into notches  40 . Particularly, blade-opening arrowhead  23  uses annular ring  82  to equally distribute the urging force to all blades  50 , whereas blade-opening arrowhead  24  does not. 
     FIGS. 11 and 12 illustrate blade-opening arrowheads  25  and  26 , having gaps  90  formed between apertures  52  of blades  50  and annular hinge pin  84 , wherein blades  50  are urged when engaging catch lips  60  into notches  40 . Particularly, blade-opening arrowhead  25  uses annular ring  82  to equally distribute the urging force to all blades  50 , whereas blade-opening arrowhead  26  does not. It is apparent that annular hinge pins  84  or hinge pins  70 , gaps  90 , apertures  52 , and blades  50 , can be altered or combined differently than suggested by the various disclosed embodiments of this invention, without deterring from the scope of this invention. 
     With reference to holding means, tip end  32  of the arrowhead bodies  30  according to this invention, may be removably attachable. For example, tip end  32  may be removably attachable to a substantially frustuconical arrowhead body  30 , as clearly shown in FIG. 2, or may be integral with arrowhead body  30 , as shown in FIG.  9 . Holding means may be comprised of rigid or resilient materials or elements, and may be comprised of voids, notches, cavities, protrusions, lips, or any combination thereof that is suitable to be contiguously engaged with the engaging area or areas of the edge of each blade  50 . For example, holding means may comprise bias means. Accordingly, the engaging area of the blade edge will be configured in any sufficient shape such that when received in, or engaged to, the holding means, each respective blade  50 , is securely held in the retracted position until the arrowhead penetrates an object or the equivalent. The engaging surfaces of each blade edge and the holding means may comprise any combination of configurations of flat, convex, concave, and inclined, such as flat to flat, flat to concave, and concave to convex. For example, a rigid flat surface of the blade edge may be urged into a resilient flat rubber piece, or a flat rigid blade edge may be urged into a flat rigid area on arrowhead body  30  or the equivalent. 
     According to this invention, each blade is preferably housed in a respective blade slot or equivalent, configured to receive the blade or blades. The blade slot or slots, are in substantial alignment with the longitudinal axis of the arrowhead body, and may be radially or non-radially orientated. The amount each blade or a particular portion of each blade, is exposed outside the arrowhead body may vary, but will be such that the arrowhead exhibits the excellent arrow trajectory and aerodynamics, characteristic of blade-opening arrowheads, and will have a sufficient moment-arm to lever or rotate the blades quickly and freely to the open position. It is apparent that the blade-opening arrowheads according to this invention may have any number of blades, with two, three or four being preferred. It is apparent that the blade-opening arrowheads according to this invention may have stationary or fixed blades attached to the arrowhead body in combination with the pivotal blades. It is apparent that the different and various elements of this invention may be made of light weight and strong materials, such as composites, aluminum alloys, titanium alloys, stainless steels and other metals and materials. It is also apparent that the arrowhead body of the blade-opening arrowheads according to this invention may be fastened to the forward end of an arrow shaft by any method, such as threading into an insert, or glueing. 
     The user-friendly and durable nature of the blade retention methods according to this invention provide blade-opening arrowheads that are easy to use, failsafe and worry-free. While the arrowheads are exposed to hard use and harsh conditions in the field, the user will appreciate the simplicity and ease involved in their use. The non-consumable nature, of the blade retention methods of the present invention, allows the archer to simply push the blades back towards the retracted position to securely re-lock the blades in the retracted position, thus quickly and easily readying the arrowhead for repeated use. When compared to prior art spring elements in ruggedness, strength and durability, the annular spring of the present invention better retains its flexibility, and ability to produce an effective urging force. Also, the humanness and lethality of blade-opening arrowheads according to this invention are enhanced over conventional arrowheads, in that the razor sharp cutting edges are continually urged forward, thus providing the ability to cut more tissue. 
     It is apparent that different bias means, hinge means, holding means and other elements and their equivalents, as discussed above and according to other preferred embodiments of this invention, can be changed, or interchanged, or eliminated, or duplicated, or made of different materials, and connected to or associated with adjacent elements in different manners, other than suggested herein, without deterring from the desired results of the blade-opening arrowheads according to this invention. 
     It is to be understood that the present invention is not limited to the sole embodiments described above, as will be apparent to those skilled in the art, but encompasses the essence of all embodiments, and their legal equivalents, within the scope of the following claims.