Variable Cutting Diameter Arrowhead

Abstract

A variable cutting diameter arrowhead includes a first blade, a second blade, and a ferrule, where the first blade and the second blade have a stowed position and a deployed position. The first blade and the second blade may be pivotally attached to the ferrule. In addition, a resilient member may be within a ferrule cavity, where the resilient member applies a force to a blade locking member that engages the first blade and the second blade to retain the blades in a stowed position. When the blades are in a deployed position, the distance between a distal end of the first blade and an outer surface of the ferrule is greater than the distance between the distal end of the first blade and the outer surface of the ferrule is in the stowed position.

We claim: 
     
         1 . An arrowhead, comprising:
 a ferrule that includes a first end, a second end, and a ferrule body extending between the first end and the second end that defines a longitudinal axis;   a first blade having a first cutting portion, wherein the first blade is pivotally attached to the ferrule at a blade pivot axis;   wherein the ferrule includes a ferrule cavity that receives a first resilient member and a second resilient member, wherein the second resilient member has a nested configuration with the first resilient member such that the first resilient member surrounds a portion of the second resilient member; and   wherein the first blade has a stowed position and a deployed position; and   wherein the first resilient member and second resilient member provide a force to deploy the first blade from the stowed position to the deployed position, and wherein a first distance between a distal end of the first blade and an outer surface of the ferrule is greater than a second distance between the distal end of the first blade and the outer surface of the ferrule when the first blade is in the deployed position than in the stowed position.   
     
     
         2 . The arrowhead of  claim 1 , wherein the first resilient member is a first compression spring, and the second resilient member is a second compression spring. 
     
     
         3 . The arrowhead of  claim 2 , wherein the first compression spring has a first free length and the second compression spring has a second free length, wherein the first free length is greater than the second free length. 
     
     
         4 . The arrowhead of  claim 1 , further comprising a second blade having a second cutting portion, wherein the second blade is pivotally attached to the ferrule at the blade pivot axis; and
 wherein the force from the first resilient member and the second resilient member also moves the second blade from a stowed position to a deployed position.   
     
     
         5 . The arrowhead of  claim 1 , wherein the first blade includes a first blade locking geometry, wherein the first blade locking geometry includes a first convex curved surface. 
     
     
         6 . The arrowhead of  claim 5 , wherein a blade locking member comprises a concave surface that contacts the first blade locking geometry when the arrowhead is in the stowed position. 
     
     
         7 . The arrowhead of  claim 1 , wherein the arrowhead further comprises:
 a trigger mechanism pivotally attached to the ferrule at a trigger pivot axis;   wherein the trigger mechanism includes a first trigger member having a first extension and a first engaging portion;   wherein the first blade includes a first deployment tab; and   wherein the first engaging portion contacts the first deployment tab when the arrowhead is in the stowed position.   
     
     
         8 . The arrowhead of  claim 7 , wherein the first trigger member includes a first channel formed between the first extension and the first engaging portion, wherein the first channel has a first end near a juncture of the first extension and the first engaging portion and a second open end having a greater width than the first end, and wherein the first deployment tab moves through the first channel when the arrowhead moves from the stowed position to the deployed position. 
     
     
         9 . An arrowhead, comprising:
 a ferrule having a first end, a second end, and a ferrule cavity;   a first blade having a first cutting portion, wherein the first blade is pivotally attached to the ferrule at a blade pivot axis;   a first resilient member and a second resilient member located within the ferrule cavity;   a blade locking member connected to an upper portion of the first resilient member;   wherein the first blade has a stowed position and a deployed position; and   wherein the first resilient member and second resilient member provide a force to deploy the first blade from the stowed position to the deployed position, and wherein a first distance between a distal end of the first blade and an outer surface of the ferrule is greater than a second distance between the distal end of the first blade and the outer surface of the ferrule when the first blade is in the deployed position than in the stowed position.   
     
     
         10 . The arrowhead of  claim 9 , wherein the first resilient member has a first spring constant and the second resilient member has a second spring constant, wherein the first spring constant is within a range of 4 to 5 times greater than the second spring constant. 
     
     
         11 . The arrowhead of  claim 9 , wherein the first resilient member has a first stowed length that is within a range of 55 percent to 65 percent of its free length and the second resilient member has a second stowed length that is within a range of 45 percent to 55 percent of its free length. 
     
     
         12 . The arrowhead of  claim 9 , wherein the first resilient member has a first deployed length that is within a range of 60 percent to 90 percent of its free length and the second resilient member has a second deployed length that is within a range of 65 percent to 75 percent of its free length. 
     
     
         13 . An arrowhead, comprising:
 a ferrule having a first end, a second end, and a ferrule cavity;   a first blade pivotally attached to the ferrule;   a second blade pivotally attached to the ferrule;   a first resilient member and a second resilient member located within the ferrule cavity; and   wherein an outer diameter of the second resilient member is less than an inner diameter of the first resilient member; and   wherein the first blade has a stowed position and a deployed position; and   
       wherein the first resilient member and second resilient member provide a force to deploy the first blade from the stowed position to the deployed position, and wherein a first distance between a distal end of the first blade and an outer surface of the ferrule is greater than a second distance between the distal end of the first blade and the outer surface of the ferrule when the first blade is in the deployed position than in the stowed position. 
     
     
         14 . The arrowhead of  claim 13 , wherein the first resilient member and the second resilient member are compression springs. 
     
     
         15 . The arrowhead of  claim 13 , wherein the first resilient member has a free length that is within a range of 10 percent to 30 percent longer than the second resilient member. 
     
     
         16 . The arrowhead of  claim 13 , wherein the first blade and the second blade each include a blade locking geometry that engages with a blade locking member that is positioned within the ferrule cavity. 
     
     
         17 . The arrowhead of  claim 16 , wherein the blade locking member is connected to upper portions of both the first resilient member and the second resilient member. 
     
     
         18 . The arrowhead of  claim 13 , further comprising a third resilient member that is nested within the first resilient member and the second resilient member. 
     
     
         19 . The arrowhead of  claim 13 , wherein the arrowhead further comprises:
 a trigger mechanism pivotally attached to the ferrule at a trigger pivot axis;   wherein the trigger mechanism includes a first trigger member having a first extension and a first engaging portion;   wherein the first blade includes a first deployment tab; and   wherein the first engaging portion contacts the first deployment tab when the arrowhead is in the stowed position.   
     
     
         20 . The arrowhead of  claim 19 , wherein the first trigger member includes a first channel formed between the first extension and the first engaging portion, wherein the first channel has a first end near a juncture of the first extension and the first engaging portion and a second open end having a greater width than the first end, and wherein the first deployment tab moves through the first channel when the arrowhead moves from the stowed position to the deployed position.