Over center expanding arrowhead

Abstract

Improvements in an expanding arrowhead where the initial launching thrust of launching an arrow keeps the blades retracted within the head of the arrow. The blades remain retracted because the center of mass of the blades is on the opposite side of the rotational pivoting axis of the blades. When the blades contact a target a wing tip on the blades pull the blades open. There are two or three blades that can be retained within the head of the arrow. The blades are loosely retained in a retracted orientation for transportation. The retention is sufficient to overcome the forces or gravity yet release with slight force on then ends of the blades. When the arrow is pulled through the wound track the blades fold back into the head or body.

Claims

1. An over center expanding arrowhead comprising: a body having a slot passing through said body; said body having a central axis; a pivot passing through said body and said pivot retains at least two blades; each of said at least two blades having a centroid of mass; each of said blades have a sharp side located a first elongated side of said centroid of mass; each of said at least blades have a tip that extends out of said body and exist on a second elongated side of said centroid of mass from said central pivot axis, and forces on said tip towards said pivot rotates said blade whereby all of said sharp side passes through said central axis of said body to an open orientation.

2. The over center expanding arrowhead according to claim 1, further includes a spring-loaded bearing that temporally retains said blades in a closed orientation.

3. The over center expanding arrowhead according to claim 1, wherein said tip has a rotational stop.

4. The over center expanding arrowhead according to claim 3, wherein said stop limits rotation of each of said at least two blades.

5. The over center expanding arrowhead according to claim 1, wherein force from launching said arrow imparts a closing force or direction to said at least two blades into a closed orientation.

6. The over center expanding arrowhead according to claim 1, wherein said at least two blades rotate into said body when said arrow is pulled through a wound path.

7. The over center expanding arrowhead according to claim 1, wherein said centroid of mass passes through said central pivot axis when said blade opens.

8. The over center expanding arrowhead according to claim 1, wherein said centroid of mass is on a first side of said central pivot axis.

9. The over center expanding arrowhead according to claim 1, wherein each of said at least two blades have a radius depression on an end that is opposite of said central pivot axis.

10. The over center expanding arrowhead according to claim 9, further includes a ball that locates within said radius depression.

11. The over center expanding arrowhead according to claim 10, wherein said ball is biased with a spring.

12. The over center expanding arrowhead according to claim 11, wherein said ball and said spring are centered in said arrowhead body.

13. The over center expanding arrowhead according to claim 12, wherein said forces on said tip overcomes forces of said spring.

14. The over center expanding arrowhead according to claim 1, wherein entry of said arrowhead in a target opens at least one of said at least two blades.

15. An over center expanding arrowhead comprising: a body having a slot passing through said body; said body having a central axis; a pivot passing through said body and said pivot retaining at least two blades; each of said at least two blades has a centroid of mass on a first side of said central axis; each of said at least blades have a first elongated side that is stored within said body when said arrowhead is launched and a second elongated side with a tip that extends out of said body; each of said at least two blades are temporally retained in at least some of said body with a retention spring, and forces on said tip overcomes a force of said retention spring and rotates each of said blades so said centroid of mass passes to a second side of said central axis to open said at least two blades out of said body.

16. The over center expanding arrowhead according to claim 15, each of said at least two blades has a stop.

17. The over center expanding arrowhead according to claim 16, wherein said stop limits rotation of each of said at least to blades.

18. The over center expanding arrowhead according to claim 15, each of said at least two blades have a radius depression near said tip.

19. The over center expanding arrowhead according to claim 18, further includes a ball that is pressed by said spring to locates said ball within said radius depression.

20. The over center expanding arrowhead according to claim 15, wherein entry of said arrowhead in a target opens at least one of said at least two blades.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

(1) FIG. 1 shows a perspective view of an over center expanding arrowhead.

(2) FIG. 2 shows a sectional view of the over center expanding arrowhead.

(3) FIG. 3 shows a single blade and the blade retention mechanism.

(4) FIG. 4 shows the over center mechanism at an arrow launch.

(5) FIG. 5 shows the blade opening as it enters a target.

(6) FIG. 6 shows the arrow in a target and removal of the arrow through the wound path.

DETAILED DESCRIPTION OF THE INVENTION

(7) It will be readily understood that the components of the present invention, as generally described and illustrated in the drawings herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in the drawings, is not intended to limit the scope of the invention but is merely representative of various embodiments of the invention. The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.

ITEM NUMBERS AND DESCRIPTION

(8) 17 central axis 18 wound path 19 target 20 over center expanding arrowhead 21 tip 22 threads, threaded 23 shank 24 fastener 25 shaft of fastener 26 tip 27 body 28 stop(s) 29 shaft 30 blade 30B dashed line 31 tip 32 pivoting axis 33 rotational mass 34 sharpened side 35 radius 36 displacement 40 blade 40B dashed line 41 tip 42 axis 43 center of rotation 44 cutting edge 45 slight radius 46 stops 47 stop 57 force 58 ball 59 spring 90 launched 90B inertia 91 rotate 92 force 93 open 94 pulling 95 rotate

(9) FIG. 1 shows a perspective view of an over center expanding arrowhead 20. In this view, the blades 30 and 40 (not shown) are shown in solid lines retracted in the body 27 of the head and as dashed lines 30B and 40B in the open orientation. The blades 30 and 40 pivot through an axis that is defined by a fastener 24. The fastener is preferably a shoulder bolt but can take other forms. The body 27 of the over center expanding arrowhead 20 includes a shank 23 with a shoulder and threads 22 that secures the over center expanding arrowhead 20 to the shaft 29 of an arrow.

(10) Each blade 30 and 40 has a tip 31 and 41 respectively that extends from the body 27 of the over center expanding arrowhead 20 while the remainder of the blades remain nested within the body. The tip 21 of the over center expanding arrowhead 20 is pointed to provide initial penetration of the over center expanding arrowhead 20 into the target. The tips 31 and 41 are arranged to make contact with a target and pull the blades 30 and 40 out of the body 27. While this figure shows two blades it is contemplated that the arrowhead can have three of four blades that fold into or across the body of the arrowhead.

(11) FIG. 2 shows a sectional view of the over center expanding arrowhead. In this figure only one blade 40 is shown with the body 27 of the over center expanding arrowhead 20. The blades can freely rotate through the majority of their travel. To minimize injury for storage and transportation the blades are tucked in the body 27 of the over center expanding arrowhead 20. To keep the blades within the body 27 the blades are retained with a spring 59 loaded ball bearing 58. A slight radius 45 is placed in leading edge of the tip 41 of the blade 40. The spring 59 is selected to provide the desired force 57 of the ball 58 to hold the blade 40 in the retracted position. The force 57 of the spring 59 is selected to provide a minimal force that is easily overcome when force is placed in the blade tip 41. A user can easily overcome the force 57 and pull the blade 40 out of the body and also push the blade back into the engagement with the ball 58 retention.

(12) FIG. 3 shows a single blade 30 and the blade retention mechanism. The blade 30 is designed with the majority of the mass of the blade 30 is placed on a particular side of the pivoting axis 32 of the blade. This figure shows the central axis 17 of the arrow passing through the pivoting axis 32 of the blade 30. The blade has a sharpened side 34 that cuts through the target. The rotational mass 33 is shown in this figure with the displacement 36 from the centerline 17 of the arrow.

(13) The blades are held within the body 27 the blades are retained with a spring-loaded ball bearing 58. A slight radius 35 is placed in leading edge of the tip 31 of the blade 30. This arrangement of the ball 58 in the cradle radius 35 allows a user to easily open and close the blade 30 from the arrowhead for inspection. While a spring-loaded bearing is shown and described it is further contemplated that the retention mechanism can be a magnet, elastomeric, friction fit or other mechanism.

(14) FIG. 4 shows the over center mechanism at an arrow launch. As previously described, the spring 59 keeps the ball in a recess of the blade 40. The arrowhead is threaded 22 onto the shaft of an arrow. When the arrow is launched 90 a high force of acceleration is placed in the arrowhead. The forward inertial force will make the blade 40 rotate 91 from the pivot axis point that is retained by the shaft of the fastener 25 towards the center of rotation 43. The launch forces the blade 40 to close within the body 27 of the arrowhead. The thrust of the launch 90 can cause the blade 40 to rotate the tip 41 into a hard stop 47 in the front of the body of the arrowhead. This will actually assist in keeping the blade closed during travel. The deceleration of the arrow as it travels may produce some forces to open the blade and air resistance on the tip 41 may further produce some opening of the blade 40, but these forces are overcome by proper selection of the ball 58 and the spring 59 to hold the ball 58 in the previously described slight radius 45 detents on the blade 40.

(15) FIG. 5 shows the blade 40 opening as it enters a target 19. The inertia 90B of the arrow will drive the over center expanding arrowhead 20 into the target. As the over center expanding arrowhead 20 enters the target 19 the tip 26 will initially penetrate. As the arrow continues into the target, the tip 41 will make contact with the target 19. The force 92 on the tip 41 will overcome the forces of the ball 58 in the detent of the blade 40. This force 92 will rotate the blade 40 open 93 as the blade 40 pivots through axis 42 on the shaft of the fastener 25 or bearing. As the blade 40 opens the cutting edge 44 passes through the body 27 of the arrowhead to the opposite side of the center of the arrowhead body.

(16) The blade 40 will continue to rotate until the stop(s) 46 of the blade 40 make contact with the stop(s) 28 in the rear portion of the arrowhead body 27. With the blades open the over center expanding arrowhead 20 will continue into the target and cut a wound path.

(17) FIG. 6 shows the arrow in a target and removal of the arrow through the wound path 18. In this figure both blades 30 and 40 are open and have cut a wound path 18. The stops 46 on the blade(s) are in contact with the stops 28 in the arrowhead body 27 to prevent further rotation of the blades.

(18) Once the arrow is within the target, the arrow can be withdrawn by pulling 94 on the shaft 29. The pulling force 94 will cause the blades 30 and 40 to rotate 95 into the closed orientation where the arrow can be withdrawn through the wound path. If an animal is not mortally wounded the animal can rub the arrow out of the wound path.

(19) Thus, specific embodiments of an over center expanding arrowhead have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims.