# Patent

## Title
High straightness arrow and method of manufacture

## Abstract

The high straightness arrow in the present invention is designed to improve the straightness of the archery arrow by adopting new manufacturing technique and method. Chamber and post are made of dissimilar metals and the chamber includes a wall that creates an external housing and defines an internal airspace. Once the post with shaft is positioned through chamber, nuts are tightened securely, forming an assembly, to straighten post. Due to the different coefficients of thermal expansion of chamber and post, when they are heated simultaneously, the chamber expands more than the post, creating a natural tension along post which results in a near perfectly straight shaft. As the assembly cools, the post and chamber return to their original length, yet the shaft retains its straightened form and thus this manufacturing process yields an arrow shaft that is straighter than shafts made of the same materials but with a traditional manufacturing technique.

## Background
CROSS REFERENCE TO RELATED APPLICATION
This application is a divisional of, and claims the benefit of priority to, U.S. Utility patent application Ser. No. 13/298,287 filed Nov. 16, 2011, now issued as U.S. Pat. No. 8,939,753, entitled “High Straightness Arrow and Method of Manufacture,” and currently co-pending, which claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 61/413,983, filed on Nov. 16, 2010, entitled “High Straightness Arrow and Method of Manufacture.”


BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates generally to archery arrows, and more specifically to techniques for improving the straightness of the arrow and method of manufacture for the high straightness arrow. The present invention is more particularly, though not exclusively, useful as a manufacturing technique which provides for more consistent straightness to the arrows.
DESCRIPTION OF THE RELATED ART
In the archery industry, there is a consistent drive towards manufacturing arrows having improved straightness. Specifically, an arrow's flight path is determined in large part by the flexibility and straightness of the arrow shaft. While some natural oscillations are expected in a carbon fiber shaft, the overall, steady state straightness is highly coveted by archers as it improves the accuracy of the arrow shot.
In light of this consistent pursuit of arrow straightness, a high straightness arrow and method of manufacture have been developed. The high straightness arrow is manufactured from carbon fiber materials generally known and used in the archery industry. Arrows manufactured using the technique of the present invention are consistently more straight than arrows made using the same materials but with a traditional manufacturing technique.
SUMMARY OF THE INVENTION
The high straightness arrow in the present invention is designed to improve the straightness of the archery arrow by adopting new manufacturing technique and method of using carbon fiber materials.
In a preferred embodiment, chamber and post are made of dissimilar metals and the chamber includes a wall that creates an external housing and defines an internal airspace. The post wrapped with a carbon fiber shaft may be inserted into the chamber and post may be threaded on its ends that extend outside chamber. Once post with shaft is positioned through chamber, nuts are tightened securely, forming an assembly, to straighten post. Due to the greater coefficient of thermal expansion of chamber than that of post, when they are heated simultaneously, the chamber length expands more than the length of the post.
At the end of the heating cycle, a difference in length of chamber and post creates a natural tension along post which results in a near perfectly straight shaft. As the assembly cools, the post and chamber return to their original length, yet the shaft retains its straightened form and thus this manufacturing process yields an arrow shaft that is straighter than shafts made of the same materials but with a traditional manufacturing technique.



BRIEF DESCRIPTION OF THE DRAWINGS
The nature, objects, and advantages of the present invention will become more apparent to those skilled in the art after considering the following detailed description in connection with the accompanying drawings, in which like reference numerals designate like parts throughout, and wherein:
FIG. 1 is a diagrammatic view of an arrow in the present invention, with an illustration of lateral flexure when it is shot;
FIG. 2 is a cross-sectional view taken along lines 2-2 of FIG. 1;
FIG. 3 is a diagrammatic view of an arrow equipped within a chamber used to manufacture the high straightness arrow and method of manufacture in the present invention;
FIG. 4 is a diagrammatic view of a chamber loaded with post, shaft and nuts illustrating the expansion of the chamber when heated; and
FIG. 5 is a graphical representation of the correspondingly expanded lengths of the chamber and post in the present invention.



DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, an arrow is shown and generally designated 100. Arrow 100 includes a shaft 102 with a tip end 104 having equipped with a point 106, and fletching 108 adjacent nock end 110 equipped with a nock 112. Arrow 100 often is manufactured with an inherent, yet unwanted, curvature shown by dashed lines 102′. This curvature creates a flight path that is not as straight as a perfectly straight arrow as the curvature results in a flight that is not axial to the arrow shaft 102. Specifically, the arrow shaft 102 bends along its length so as to deflect a distance 114. As a result of the non-linear flight, the target is often missed.
FIG. 2 is a cross-sectional view of the arrow 100 as taken along lines 2-2 of FIG. 1 which illustrates a shaft 102 having a diameter 116, a wall thickness 118, and defines an internal bore 120. These dimensions can vary depending on the type of arrow being manufactured, and can be increased or decreased depending on the materials used in the shaft, as well as the style of arrow being manufactured.
The chamber used to manufacture the high straightness arrow and method of manufacture is shown in FIG. 3 with a portion cut away for clarity, and generally designated 150. Chamber 150 includes a wall 152 that creates an external housing 154 and defines an internal airspace 156. Wall 152 is formed with a pair of holes 158 through which a post 160 can be inserted such that post 160 passes longitudinally through the internal chamber 156. It is appreciated that chamber 150 may be made such that the post 160 wrapped with a carbon fiber shaft 102 may be inserted. For instance, chamber 150 may have multiple pieces, a removable cover, or the holes 158 are sized to pass post 162 with shaft 102 through the length of the chamber 150. Post 160 may be threaded on its ends that extend outside chamber 150. Once post 160 with shaft 102 is positioned through chamber 150, nuts 162 and 164 are tightened securely to straighten post 160.
In a preferred embodiment, chamber 150 and post 160 are made of dissimilar metals. Specifically, the coefficient of thermal expansion of chamber 150 is greater than that of post 160 such that when they are heated simultaneously, the chamber 150 length expands more than the length of the post 160.
As shown in FIG. 4, chamber 150 is loaded with post 160 and shaft 102, and nuts 162 and 164 are securely tightened in place to form an assembly. In this configuration, chamber 150 has a length 170 at the starting temperature. Once tightened, the entire assembly is placed into an oven or other heat source. This heat source heats the assembly such that shaft 102 is exposed to a uniform heat. In a preferred embodiment, chamber 150 may be tubular so that the distance from the longitudinal walls of the device are the same along the length of the arrow shaft 102. Once heated the chamber expands to a length 172 that is greater than the length of the post 160 expansion length.
Referring to FIG. 5, a graphical representation 200 of the correspondingly expanded lengths of the chamber 150 and post 160 are shown. Specifically, graph 200 includes a representative graph of the expanded length of the chamber as a function of temperature. Chamber 150 begins with original length 170 and as the temperature rises, the length of the chamber increases as dashed line shows to length 172. The length of the post 160, however, begins at length 170, yet expands at a lesser rate as shown by solid line 202. At the end of the heating cycle, there is a difference in length 204 that creates a natural tension along post 160 which results in a near perfectly straight shaft 102.
As the assembly cools, the post and chamber return to their original length, yet the shaft retains its straightened form and thus this manufacturing process yields an arrow shaft that is straighter than shafts made with different techniques.
While there have been shown what are presently considered to be preferred embodiments of the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope and spirit of the invention.

## Claims

1. A method of manufacturing a high straightness arrow shaft having a straightness factor comprising the steps of:
providing a chamber comprising a wall forming an external housing and a chamber length, said chamber further comprising a first metal having a first coefficient of thermal expansion, said chamber length increases as temperature rises from a starting temperature and decreases as the temperature lowers;
providing a post having a first end, a second end, and extending through said chamber and sized to receive multiple windings of fiber reinforced plastic, said post comprising a second metal having a second coefficient of thermal expansion smaller than said first coefficient of thermal expansion, said post further having a post length, wherein said post length increases as the temperature rises and decreases as the temperature lowers, at a slower rate than said chamber length;
applying a carbon fiber material to said post;
installing said post and said carbon fiber material within said chamber;
heating said chamber, said post, and said carbon fiber material, wherein said chamber length expands more than said post length when heat is applied, configured to create tension along said post;
curing said carbon fiber material on said post, said carbon fiber material curing into a high straightness arrow shaft;
cooling said chamber, said post, and said high straightness arrow shaft;
removing said post and said high straightness arrow shaft from said chamber; and
removing said high straightness arrow shaft from said post.

2. The method of manufacturing a high straightness arrow shaft of claim 1, wherein said post is further configured with external threads to accept an internally threaded nut.

3. The method of manufacturing a high straightness arrow shaft of claim 1, wherein said chamber further comprises a first wall having at least one first hole and a second wall having at least one second hole, wherein said first wall and said second wall are disposed on opposite sides of said chamber such that each said at least one first hole and each said at least one second hole are disposed in pairs and are coaxially located on said first wall and said second wall.

4. The method of manufacturing a high straightness arrow shaft of claim 3, wherein each said at least one first hole and each said at least one second hole are sized to accept said first end and said second end of said post.

5. The method of manufacturing a high straightness arrow shaft of claim 3, wherein each said at least one first hole and each said at least one second hole are sized to accept said post wrapped with said multiple windings of fiber reinforced plastic.

6. The method of manufacturing a high straightness arrow shaft of claim 1, wherein said chamber further comprises a removable cover.

7. The method of manufacturing a high straightness arrow shaft of claim 1, wherein said chamber further comprises a tubular shape, allowing heating of said chamber, said post, and said carbon fiber material simultaneously.

8. The method of manufacturing a high straightness arrow shaft of claim 1, wherein the difference between said first coefficient of thermal expansion and said second coefficient of thermal expansion causes said post to be exposed to a tension force when said chamber is exposed to a heat source.

9. The method of manufacturing a high straightness arrow shaft of claim 1, wherein said step of applying a carbon fiber material to said post comprises the step of wrapping said carbon fiber material around said post.

10. The method of manufacturing a high straightness arrow shaft of claim 1, wherein said step of installing said post and said carbon fiber material within said chamber comprises the step of inserting said post longitudinally within said chamber, said first end of said post extending through said at least one first hole of said first wall and said second end of said post extending through said at least one second hole of said second wall.

11. The method of manufacturing a high straightness arrow shaft of claim 2, wherein said step of installing said post and said carbon fiber material within said chamber further comprises the step of threading a first nut on said first end of said post and threading a second nut on said second end of said post, wherein said first nut and said second nut are securely tightened to straighten said post.

12. The method of manufacturing a high straightness arrow shaft of claim 1, wherein said step of heating said chamber, said post, and said carbon fiber material comprises a step of placing said chamber, said post, and said carbon fiber material into a heat source.

13. The method of manufacturing a high straightness arrow shaft of claim 1, wherein a heat source is an oven.

14. The method of manufacturing a high straightness arrow shaft of claim 13, wherein said step of heating said chamber, said post, and said carbon fiber material further comprises a step of exposing said chamber, said post, and said carbon fiber material to said heat source.

15. The method of manufacturing a high straightness arrow shaft of claim 1, wherein said step of curing said carbon fiber material on said post, said carbon fiber material curing into a high straightness arrow shaft comprises a step of maintaining said heat source at a curing temperature at an end of a heating cycle, wherein at the end of said heating cycle, a difference in length between said chamber length and said post length results in said tension along said post.

16. The method of manufacturing a high straightness arrow shaft of claim 1, wherein said step of cooling said chamber, said post, and said high straightness comprises the step of stopping a heat source.

17. A method of manufacturing a high straightness arrow shaft having a straightness factor comprising the steps of:
providing a chamber comprising a wall forming an external housing, a first wall having at least one first hole and a second wall having at least one second hole, wherein said first wall and said second wall are disposed on opposite sides of said chamber such that each said at least one first hole and each said at least one second hole are disposed in pairs and are coaxially located on said first wall and said second wall, and a chamber length, said chamber further comprising a first metal having a first coefficient of thermal expansion, said chamber length increases as temperature rises from a starting temperature and decreases as the temperature lowers;
providing a post extending through said chamber and sized to receive multiple windings of fiber reinforced plastic having a first end and a second end, said post further comprising a second metal having a second coefficient of thermal expansion smaller than said first coefficient of thermal expansion and a post length, wherein said post length increases as the temperature rises and decreases as the temperature lowers, at a slower rate than said chamber length;
applying a fiber reinforced plastic to said post;
installing said post and said fiber reinforced plastic within said chamber;
heating said chamber, said post, and said fiber reinforced plastic;
curing said fiber reinforced plastic on said post, said fiber reinforced plastic curing into a high straightness arrow shaft;
cooling said chamber, said post, and said high straightness arrow shaft;
removing said post and said high straightness arrow shaft from said chamber; and
removing said high straightness arrow shaft from said post.

18. The method of manufacturing a high straightness arrow shaft of claim 17, wherein said step of installing said post and said fiber reinforced plastic within said chamber comprises the step of:
inserting said post longitudinally within said chamber, said first end of said post extending through said at least one first hole of said first wall and said second end of said post extending through said at least one second hole of said second wall; and
securing said first end of said post to said first hole and securing said second end of said post to said second hole, wherein said post is tightened to straighten said post and create tension along said post.

19. The method of manufacturing a high straightness arrow shaft of claim 17, wherein said step of heating said chamber, said post, and said fiber reinforced plastic comprises the steps of:
placing said chamber, said post, and said fiber reinforced plastic into a heat source; and
exposing said chamber, said post, and said fiber reinforced plastic to said heat source.

20. The method of manufacturing a high straightness arrow shaft of claim 17, wherein said step of curing said carbon fiber material on said post, said fiber reinforced plastic curing into a high straightness arrow shaft comprises the step of maintaining said heat source at a curing temperature at the end of a heating cycle, wherein at the end of said heating cycle a difference in length between said chamber length and said post length results in said tension along said post.