Abstract:
Disclosed is an arrowhead in which a plurality of expandable blades can be quickly and reliably retracted or expanded without using an additional means to bundle the expanding blades, thereby enhancing the penetrating capability or killing capability of an arrow. Particularly, a portion of a shaft forming the arrowhead is provided with a rack gear portion formed thereon and a lower end of each of the expanding blades is provided with a pinion gear portion, such that the rack gear portion and the pinion gear portion engage with each other and such a rack-pinion action controls the operation of retracting or expanding the expanding blades.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, in general, to an arrowhead having expanding blades capable of being retracted or expanded by a gear mechanism, and, more particularly, to an arrowhead in which a rack gear formed on a shaft is engaged with pinion gears of expanding blades coupled to a main body, and thus a relative movement between the main body and the shaft causes the retraction or expansion of the expanding blades. 
     2. Description of the Related Art 
     Generally, an arrow is composed of a hollow arrow shaft, an arrowhead attached to a leading end of the arrow shaft, the nock of an arrow using which the arrow is fit in the string, and feathering for securing the flight stability of an arrow. 
     The arrowhead serves to pass through a target, so it should have excellent wear resistance and strength and it should have a structure enabling its flight to be stable, because upon hitting the target, the accumulated energy of an arrow is collected upon the arrowhead. 
     Generally, an arrowhead has a sharpened tip to improve penetration, but such a sharpened arrowhead is not practical for certain types of hunting. This is because it is difficult for the sharpened arrowhead to kill large game and thus gain control over the same. Thus, for this reason, a broad type arrowhead which has two to four sharp blades on its edge to induce profuse bleeding and the death of game may be used. 
     There is also disclosed a variety of arrowheads in which the blades are normally retracted inside the arrowhead and expand upon hitting a target because the blades of the broad type arrowhead affect the flight stability of an arrow. 
     Such blades having an expandable structure are referred to as expanding blades. A variety of conventional examples of arrowheads having such expanding blades are disclosed in U.S. Pat. No. 5,082,292 entitled “BROADHEAD WITH DEPLOYABLE CUTTING BLADES,” U.S. Pat. No. 5,066,021 entitled “ARROW SYSTEM,” U.S. Pat. No. 4,973,060 entitled “ARROHEAD WITH EXPANDABLE BLADES,” U.S. Pat. No. 6,669,586 entitled “EXPANDING BROADHEAD,” U.S. Pat. No. 6,258,000 entitled “PENETRATION ENHANCING AERODYNAMICALLY FAVORABLE ARROWHEAD,” U.S. Pat. No. 6,287,223 entitled “DULLING PREVENTION FOR SHARP CUTTING EDGE OF BLADE-OPENING ARROWHEAD BLADES WHEN IN A CLOSED IN-FLIGHT POSITION,” U.S. Pat. No. 8,062,155 entitled “ARROWHEAD HAVING BOTH FIXED AND MECHANICALLY EXPANDABLE BLADES,” and U.S. Pat. No. 6,200,237 entitled “SLIDING BODY EXPANDING BROADHEAD,” respectively. 
     All of the patent documents described above disclose an arrowhead having two to four expanding blades, in which, when an arrow hits a target, such as game, a plurality of expanding blades are expanded to enlarge and more deeply penetrate into the wound of the game, thereby enhancing the killing capability of the arrow. 
     However, such conventional expanding blades have a problem in that, when an arrow is flying after being shot, the expanding blades expand by themselves, thereby degrading the flight stability of the arrow and adversely affecting the hit rate and flight distance of the arrow. 
     Due to such a problem, in the case of an arrowhead having the conventional expanding blades, the plurality of expanding blades must be typically retracted and grouped together before an arrow is shot, and then be tied by a band or string which can be easily broken or slip off when the arrow hits the target. 
     In doing so, the expanding blades are maintained in a retracted state during flight of the arrow, but can be expanded by slipping-off of the band or string as soon as the arrow hits and penetrates into the target. 
     However, in such a manner in which the expanding blades should be retracted and then tied or bundled by the band and the like, there are inconveniences in that the retracted expanding blades must be bundled by the band and the like whenever an arrow is shot, and in turn the band must be always carried when hunting. 
     Therefore, there is a need to develop an arrowhead in which, during flight of an arrow, retracted expanding blades can be kept un-expanded to ensure the flight stability without using an additional means, and the expanding blades can automatically expand only when the arrow hits and penetrates into a target. 
     Documents of Related Art
     U.S. Pat. No. 5,082,292 entitled “BROADHEAD WITH DEPLOYABLE CUTTING BLADES”;   U.S. Pat. No. 5,066,021 entitled “ARROW SYSTEM”;   U.S. Pat. No. 4,973,060 entitled “ARROHEAD WITH EXPANDABLE BLADES”;   U.S. Pat. No. 6,669,586 entitled “EXPANDING BROADHEAD”;   U.S. Pat. No. 6,258,000 entitled “PENETRATION ENHANCING AERODYNAMICALLY FAVORABLE ARROWHEAD”;   U.S. Pat. No. 6,287,223 entitled “DULLING PREVENTION FOR SHARP CUTTING EDGE OF BLADE-OPENING ARROWHEAD BLADES WHEN IN A CLOSED IN-FLIGHT POSITION”;   U.S. Pat. No. 8,062,155 entitled “ARROWHEAD HAVING BOTH FIXED AND MECHANICALLY EXPANDABLE BLADES”; and   U.S. Pat. No. 6,200,237 entitled “SLIDING BODY EXPANDING BROADHEAD.”   

     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is intended to provide an arrowhead having expanding blades capable of being retracted or expanded as required, in which the expanding blades can be maintained in a retracted state without using an additional means to bundle up the expanding blades during flight of an arrow, and then can quickly and reliably expand only when the arrow hits a target. 
     In order to achieve the above object, according to one aspect of the present invention, there is provided an arrowhead having expanding blades controlled by a gear mechanism, including: a penetrating tip including a sharpened leading end and a screw thread formed on an inner peripheral surface thereof; a main body adapted to allow a lower end of the penetrating tip to be inserted therein, the main body including a body portion having a hollow portion therein and opened on upper and lower end sides thereof, a plurality of expanding blade coupling pieces formed on an outer surface of the body portion, and a plurality of expanding blade receiving grooves respectively formed on a surface of each of the plurality of expanding blade coupling pieces; a plurality of expanding blades respectively hingedly and rotatably coupled to each of the expanding blade coupling pieces, the plurality of expanding blades each including a blade formed on one side end thereof and a pinion gear portion formed on a lower end thereof; a shaft including a body portion, a front-end threaded portion formed on an upper end of the body portion to be coupled to the screw thread of the penetrating tip, a rear-end threaded portion formed on a lower end of the body portion to be coupled to an arrow shaft, a rack gear portion formed on an outer peripheral surface of the body portion to engage with the pinion gear portion, and a stopper formed to protrude from the outer peripheral surface below the rack gear portion; and a spring mounted and elastically supported between the stopper and the main body; wherein a relative movement between the rack gear portion and the pinion gear portion causes the retraction or expansion of the expanding blades. 
     In this case, the spring may be inserted onto the shaft such that a lower end of the spring is supported by the stopper, and an upper end of the spring is fixedly coupled on an inner diameter surface of the main body. 
     Preferably, the penetrating tip may include a tip portion provided with a tip edge and a cylindrical body portion having the screw thread formed on an inner peripheral surface thereof, and a shoulder may be defined between the tip portion and the cylindrical body portion. 
     Also, the main body may be opened on upper and lower ends thereof to communicate with the hollow portion therein, and an outer diameter of the main body is gradually reduced from the lower end to the upper end. 
     Also, the shape of the pinion gear portion may be overall that of an arc and may include streamline-shaped protrusions and streamline-shaped grooves alternately formed on a lower end thereof. 
     Furthermore, each of the expanding blades may include a spur formed on a front end thereof to be folded at a predetermined angle relative to the blade. 
     Additionally, the stopper may be formed to protrude in a circular shape from an outer peripheral surface of the body portion between the rear-end threaded portion and the rack gear portion such that the diameter of the stopper may be larger than the diameter of the body portion. 
     According to the present invention, the following effects may be obtained. 
     The plurality of expanding blades provided in the arrowhead is maintained in a retracted state without using an additional means to bundle the expanding blades during flight of an arrow and then expand only when the arrow hits a target, thereby providing excellent flight stability of the arrow and very excellent killing capability against a target. 
     Particularly, means or mechanisms for retracting or expanding the plurality of expanding blades in a timely manner have a simple structure, thereby easily assembling or manufacturing the arrowhead and also obtaining the trouble-free arrowhead. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  shows a perspective view of an arrowhead with expanding blades retracted according to the present invention; 
         FIG. 2  shows a perspective view of the arrowhead with the expanding blades expanded according to the present invention; 
         FIG. 3  shows an exploded perspective view of the arrowhead according to the present invention; 
         FIG. 4  shows a front view of the arrowhead according to the present invention; 
         FIG. 5  shows a plan view of the arrowhead of  FIG. 4 ; 
         FIG. 6  shows a perspective view and a front sectional view of a penetrating tip according to the present invention; 
         FIG. 7  shows a perspective view, a front view, a plan view and a bottom view of a main body according to the present invention; 
         FIG. 8  shows a perspective view and a front view of an expanding blade according to the present invention; 
         FIG. 9  shows a perspective view of a spring according to the present invention; and 
         FIG. 10  shows a perspective view and a front view of a shaft according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in greater detail to the construction and operating principle of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. 
       FIG. 1  shows a perspective view of an arrowhead with expanding blades retracted according to the present invention,  FIG. 2  shows a perspective view of the arrowhead with the expanding blades expanded according to the present invention,  FIG. 3  shows an exploded perspective view of the arrowhead according to the present invention,  FIG. 4  shows a front view of the arrowhead according to the present invention, and  FIG. 5  shows a plan view of the arrowhead of  FIG. 4 . 
     An arrowhead  100  according to the present invention generally includes a penetrating tip  110  for penetrating into a target, a main body  120  having a hollow portion therein and adapted to allow the penetrating tip  110  and a shaft  150  as described below to be partially inserted therein, a plurality of expanding blades  130  rotatably mounted on the main body  120 , a spring  140 , and the shaft  150  extending through the main body  120  and threadably coupled to the penetrating tip  110 . 
       FIG. 1  shows a state of retraction of the plurality of expanding blades  130 , and, for convenience, illustrates in a transparent manner the main body  120  to aid the understanding of an inside structure thereof. 
       FIG. 6  shows a perspective view and a front sectional view of the penetrating tip according to the present invention. When an arrow hits a target, the penetrating tip  110  is adapted to penetrate into the skin and flesh of game as the target and has a sharpened leading end. The penetrating tip  110  has a tip portion  111  at its front end and a cylindrical body portion  112  at its rear end, and a boundary portion between the tip portion  111  and the cylindrical body portion  112  is provided with a shoulder  113  as shown. 
     The tip portion  111  has flat tip surfaces  111   a  and tip edges  111   b  formed by sharpened corners. 
     A cylindrical tip body  112   a  of the body portion  112  has an inner peripheral surface provided with a screw thread  112   b  to be coupled to a front-end threaded portion  152  of the shaft  150  as described below. 
       FIG. 7  shows a perspective view, a front view, a plan view and a bottom view of the main body according to the present invention. The main body  120  has a hollow portion  121   a  vertically extending through and with openings at upper and lower end sides of a body portion  121 , and an outer surface of the body portion  121  is provided with a plurality of expanding blade coupling pieces  122  protruding from the outer surface. 
     The body portion  121  preferably has a truncated cone shape in which its outer diameter is generally gradually reduced from a lower end to an upper end, but it is not necessary to be limited to such a configuration. 
     Each of the expanding blade coupling pieces  122  has a hinge shaft coupling hole  122   a  extending through side surfaces thereof, an expanding blade receiving groove  122   b  elongatedly formed on the other surface in a longitudinal direction of the main body  120  as shown. 
     The whole or a portion of the expanding blade receiving groove  122   b  is formed to communicate with the hollow portion  121   a  inside the body portion  121 , thereby allowing a pinion gear portion  134  of the expanding blade  130  as described below to engage with a rack gear portion  154  of the shaft  150  as described below. 
       FIG. 8  shows a perspective view and a front view of an expanding blade according to the present invention. As shown, the expanding blade  130  of the invention generally includes a body portion  131  having a blade  132  formed on its one side end, a spur  133  formed in a folded or bended shape on an upper end of the body portion  131 , and the pinion gear portion  134  formed on a lower end of the body portion  131 . The body portion  131  is also provided with a hinge shaft coupling hole  131   a  extending through a flat surface thereof. 
     The pinion gear portion  134  has a plurality of streamline-shaped protrusions  134   a  and a plurality of streamline-shaped grooves  134   b  alternately formed on a generally semicircular-shaped arc end thereof, and engages with the rack gear portion  154  of the shaft  150  as described below. 
     It is not necessary for the shape of gear teeth in the pinion gear portion  134  to be limited to the streamline-shaped curved surface, and this shape may be substituted for by any other shape as required. Accordingly, it should be appreciated by those skilled in the art that such a configuration may also fall within the spirit and scope of the invention. 
       FIG. 10  shows a perspective view and a front view of the shaft according to the present invention. The shaft  150  of the invention is coupled to the penetrating tip  110  at its upper end and to an arrow shaft (not shown) at its lower end. The shaft  150  generally includes a cylindrical body portion  151 , the front-end threaded portion  152  formed on a front end of the body portion  151 , a rear-end threaded portion  153  formed on a rear end of the body portion  151 , a stopper  155  protruding from an outer diameter surface of the body portion  151 , and the rack gear portion  154  formed on an outer peripheral surface of the body portion  154  located above the stopper  155 . 
     The front-end threaded portion  152  is coupled to the screw thread  112   b  formed on the inner peripheral surface of the body portion  112  of the penetrating tip  110 , and the rear-end threaded portion  153  is threadably coupled and fixed to the front end of the arrow shaft (not shown) in which the arrowhead  100  is inserted. 
     On the rack gear portion  154  formed on the outer peripheral surface of the body portion  151  there are disposed in an alternating fashion a plurality of streamline-shaped protrusions  154   a  and a plurality of streamline-shaped grooves  154   b . Reference numeral  151   a , which is indicated in the drawings but not described in detail herein, designates a groove with a predetermined length formed on an outer surface of an upper end of the body portion  151 . 
     Similar to the pinion gear portion  134  of the expanding blade  130  as described above, is not necessary for the shape of gear teeth constituting the rack gear portion  154  to be limited to such a streamline shape, and this shape may be substituted for by other shapes as required. 
     The stopper  155  formed on an outer surface of the body portion  151  between the rear-end threaded portion  153  and the rack gear portion  154  protrudes and has a diameter larger than the diameter of the body portion  151 . 
     An upper end of the spring  140  is fixed on an inner diameter portion of the main body  120 , or is caught and supported on an inner diameter surface of the main body  120 . The appearance of the spring  140  is shown in  FIG. 9 . 
     The arrowhead  100  according to the present invention constituted of the components as described above is in a retracted state wherein the plurality of expanding blades  130  are retracted as shown in  FIG. 1 , before the arrow is shot, which changes to an expanded state after the plurality of expanding blades  130  have rotated and expanded downwards as shown in  FIG. 2 , when the arrow has been shot and hit a target. 
     In the retracted state as shown in  FIG. 1 , the spring  140  is left in a compressed state, and the pinion gear portion  134  of each of the expanding blades  130  is engaged with an upper end of the rack gear portion  154  of the shaft  150 . 
     Then, when the arrow has been shot and hits the target, the penetrating tip  110  penetrates into the skin and flesh of game which is the target, during which the shaft  150  compresses the spring  140  against the main body  120  while moving forward relative to the main body  120 . 
     As the shaft  150  moves forward inside the main body  120 , the pinion gear portion  134  of each of the expanding blades  130  engaged with the upper end of the rack gear portion  154  is expanded by being rotated from up to down. 
     Namely, the rack gear portion  154  moves forward to rotate the pinion gear portion  134 , and as a result, the expanding blades  130  are rotated about hinge shafts (not shown). 
     According to the arrowhead of the present invention having the structure described above, the expanding blades  130  are always maintained in a state of engaging with the rack gear portion  154 . Therefore, the expanding blades  130  are stably maintained in the retracted state while the arrow is flying when no impact has been applied thereon, but on the other hand, the expanding blades  130  quickly and efficiently expand when they hit the target. 
     Therefore, an additional means for preventing the unexpected expansion of the expanding blades  130  during flight of the arrow is not required, and a hitting effect against the target is reliable such that ascendancy over the game can be quickly and efficiently gained in a short time. 
     In the embodiment shown, three expanding blades  130  are installed on the outer surface of the main body  120  at intervals of 120 degrees in a circumferential direction. However, it is not necessary to limit the configuration to that shown, and the number of the expanding blades  130  may be two or four or more as required. 
     In the above embodiment, an up-and-down rotation angle between the retracted state and the expanded state of the expanding blades  130  is preferably, but not limited to, between roughly 100 degrees to 120 degrees. 
     As set forth above, the present arrowhead has a plurality of expanding blades to more efficiently and reliably hit game which is the target, in which an operation of retracting or expanding the expanding blades can be reliably performed. Further the present arrowhead has a simple structure and excellent durability. 
     Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.