Abstract:
The internally fluted arrows and arrow shafts made by the process of the present invention are designed to have decreased weight and improved stiffness. Fitted components can be used with the internally fluted arrows and arrow shafts.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/210,091 filed Aug. 26, 2015. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The disclosure relates to archery arrows, arrow shafts, and crossbow bolts. The invention particularly relates to internally fluted arrow shafts and their related components as well as methods of manufacturing arrow shafts and crossbow bolts with fluted internal diameters. 
       BACKGROUND 
       [0003]    In the archery industry, there is a consistent drive to manufacture arrows having decreased weight and increased durability. Traditionally, arrow shafts were made from lightweight wood, bamboo, and reeds. To decrease their weight and produce arrows that are easier to shoot and that can fly farther, modern arrows are made from aluminum and fiber reinforced plastic. Carbon fiber, a type of fiber reinforced plastic, has been used since the 1990s as a lightweight material used to make arrows. While modern materials are lighter in weight than traditional materials, modern materials are not as durable. Moreover, while modern materials are lighter, there is a consistent pursuit to decrease arrow weight. 
       SUMMARY OF THE INVENTION 
       [0004]    A principal object of the present invention is an arrow shaft comprising a tubular core comprising a longitudinal axis, a fluted inside diameter spanning the longitudinal axis, and a cylindrical outside diameter spanning the longitudinal axis; and a wrap surrounding the outside diameter of the tubular core. The fluted arrow can be manufactured from metal or fiber reinforced plastic, such as carbon fiber, or other materials generally known and used in the archery industry. The fluting increases stiffness while maintaining arrow strength and durability. 
         [0005]    An object of the present invention is a tubular core for an arrow shaft comprising a pultruded plurality of fiber reinforced plastic filaments having a longitudinal axis, a fluted inside diameter spanning the longitudinal axis, and a cylindrical outside diameter spanning the longitudinal axis. Another object of the invention is a tubular core for an arrow shaft comprising a cast metal having a longitudinal axis, a fluted inside diameter spanning the longitudinal axis, and a cylindrical outside diameter spanning the longitudinal axis. 
         [0006]    One object of the present invention is a method of making an arrow with a pultruded fluted core comprising pultruding a fluted fiber reinforced plastic tubular core comprising a longitudinal axis, a fluted inside diameter spanning the longitudinal axis, and a cylindrical outside diameter spanning the longitudinal axis; and wrapping a material around the outside diameter of the tubular core. Another object of the invention is a method of making an arrow with a cast fluted core comprising casting a fluted metal tubular core comprising a longitudinal axis, a fluted inside diameter spanning the longitudinal axis, and a cylindrical outside diameter spanning the longitudinal axis; and wrapping a material around the outside diameter of the tubular core. 
         [0007]    One object of the present invention is a carbon fiber arrow shaft comprising rolled unidirectional carbon fiber comprising a longitudinal axis, a fluted inside diameter spanning the longitudinal axis; and a cylindrical outside diameter spanning the longitudinal axis. Another object of the present invention is a method of making a fluted arrow shaft comprising rolling a first unidirectional carbon fiber around an externally fluted mandrel to form a fluted carbon fiber tubular core having a longitudinal axis, a fluted inside diameter spanning the longitudinal axis, and a cylindrical outside diameter spanning the longitudinal axis; and wrapping a second unidirectional carbon fiber around the fluted carbon fiber tubular core to form the fluted arrow shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    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: 
           [0009]      FIG. 1  is a side view of a standard target arrow, depicting the interaction of the arrow shaft, arrowhead, nock, and fletching; 
           [0010]      FIG. 2  is a cross-sectional view of  FIG. 1  showing the typical cross section of an arrow; 
           [0011]      FIG. 3( a )  is a cross-sectional view of  FIG. 1  showing the cross section of an arrow with a fluted diameter with convex fluting or external C-fluting; 
           [0012]      FIG. 3( b )  is a cross-sectional view of  FIG. 1  showing the cross section of an arrow with a fluted diameter with concave fluting or internal C-fluting; 
           [0013]      FIG. 3( c )  is a cross-sectional view of  FIG. 1  showing the cross section of an arrow with a fluted diameter with concave and convex fluting; 
           [0014]      FIG. 3( d )  is a cross-sectional view of  FIG. 1  showing the cross section of an arrow with a fluted diameter with V-fluting; 
           [0015]      FIG. 4  is a detailed cross-sectional view of  FIG. 1  showing a cross section of an arrow with a fluted diameter with concave fluting or external C-fluting; and 
           [0016]      FIG. 5  is a detailed cross-sectional view of  FIG. 1  showing the cross section of an arrow with a fluted diameter with concave fluting or external C-fluting. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    The description that follows includes preferred embodiments of the present invention, which are exemplary and specifically described with reference to the drawings. However, dimensions, materials, shapes, relative arrangements, and other constituent elements described in the following embodiments may be changed depending on the conditions of the various elements or devices or apparatuses to which the present invention is applied. Therefore, the scope of the present invention is not limited to the precise disclosure unless otherwise specified. For example, while the disclosure generally relates to archery arrows and arrow shafts, a person of skill in the art would appreciate that the teachings are applicable to crossbow bolts. 
         [0018]      FIG. 1  is a side view of a standard target arrow, depicting the interaction of the arrow shaft, arrowhead, nock, and fletching.  FIG. 1  shows a standard arrow which is generally designated  100 . Arrow  100  includes a shaft  102  with a tip end  104  equipped with an arrowhead  106  and tail  110  equipped with fletching  108  and a nock  112 . Arrow  100  is a standard target arrow, commonly used in a bow (not shown). 
         [0019]    The arrowhead  106  and nock  112  are internally fitted components that fit inside of an internal diameter of the arrow shaft. Non-limiting examples of internally fitted components that are arrowheads  106  include broadhead adapters and target points. Non-limiting examples of internally fitted components that are nocks  112  include standard nocks and lighted nocks. An insert may be an internally fitted component or may be used with an internally fitted component to fit an arrowhead  106  or nock  112  inside of the internal diameter of the arrow shaft. Non-limiting examples of inserts include screw-in inserts, standard inserts, and threaded inserts. Internally fitted components are specifically made to be disposed in the internal diameter of the arrow shaft. 
         [0020]      FIG. 2  is a cross-sectional view of  FIG. 1  showing the typical cross section of an arrow. The shaft  102  has a diameter  134 , a wall thickness  136 , and defines an internal bore  138  and an internal diameter  140 . The present invention specifically contemplates an arrow  100  and/or an arrow shaft  102  having a fluted internal diameter. Fluting refers to the grooves or the pattern of grooves and/or ridges on the interior diameter of an arrow  100  and/or an arrow shaft  102 .  FIGS. 3( a )-3( d )  depict cross-sectional views of an arrow  100  and/or an arrow shaft  102  with a fluted internal diameter  150 . In the context of the invention, the fluted shaft  102  has a diameter  144 , a wall thickness  146 , and defines an internal fluted bore  148  and an internal fluted diameter  150 . These dimensions can vary depending on the type of arrow being manufactured and can be increased or decreased depending on the materials used in shaft  102 , as well as the style of arrow being manufactured. 
         [0021]      FIG. 3( a )  depicts convex fluting or external C-fluting.  FIG. 3( b )  depicts concave fluting or internal C-fluting.  FIG. 3( c )  depicts concave and convex fluting.  FIG. 3( d )  depicts V-fluting. These types of fluting are merely exemplary and non-limiting. Other patterns and styles of fluting may be apparent and known to those having skill in the art. 
         [0022]      FIGS. 4 and 5  are detailed cross-sectional views of  FIG. 1  showing a cross section of an arrow with a fluted diameter with convex fluting or external C-fluting.  FIGS. 4 and 5  are non-limiting and depict specifications for particular embodiments of internally fluted arrows. 
         [0023]    The tubular core of a fluted arrow shaft can be made by molding fiber reinforced plastic, pultruding carbon fiber, or casting a metal, such as aluminum. The tubular core can be formed from any other material known to those of skill in that art. The tubular core can also be formed by shaping fiber reinforced plastic, carbon fiber, or aluminum around a mandrel. The mandrel can be ridged and/or fluted so that the material being shaped around it will have the corresponding flute and/or ridge. 
         [0024]    Once the tubular core is formed, the external diameter can be wrapped. The material used for the wrap can be fiber reinforced plastic, pultruded carbon fiber, or cast metal, such as aluminum. The wrap can be formed from any other material known to those of skill in that art. The material used for wrapping can be the same as the material used to form the tubular core or the material can be different from the material used to form the tubular core. By way of non-limiting example, the core can be made of a metal, such as aluminum, and the wrap can be made of a fiber reinforced plastic, such as carbon fiber; the core can be made of a fiber reinforced plastic, such as carbon fiber, and the wrap can be made of a metal, such as aluminum; the core and wrap can both be made of a fiber reinforced plastic; or the core and wrap can both be made of a metal. 
         [0025]    The fluted arrow shaft can be formed by rolling a first unidirectional carbon fiber around an externally fluted mandrel to form a fluted carbon fiber tubular core. The unidirectional carbon fiber material can be cut patterns of unidirectional carbon fiber. In one embodiment, the unidirectional carbon fiber is rolled at an essentially 0 degree angle. A second unidirectional carbon fiber can be wrapped around the tubular core to form the fluted arrow shaft. In one embodiment, the second unidirectional carbon fiber is wrapped at an essentially 90 degree angle. In another embodiment, the second unidirectional carbon fiber is wrapped at an essentially 45 degree angle. In an embodiment, the second unidirectional carbon fiber is a woven material. 
         [0026]    The above description sets forth, rather broadly, a summary of the disclosed embodiments. There may be, of course, other features of the disclosed embodiments that will be appreciated by a person of skill in the art based on the description and may form the subject matter of claims. The features, functions, and advantages that have been discussed can be achieved independently in various embodiments of the disclosure or may be combined in yet other embodiments, further details of which can be seen with reference to the description and drawings. 
         [0027]    The order in which the steps are presented is not limited to any particular order and does not necessarily imply that they have to be performed in the order presented. It will be understood by those of ordinary skill in the art that the order of these steps can be rearranged and performed in any suitable manner. It will further be understood by those of ordinary skill in the art that some steps may be omitted or added and still fall within the spirit of the invention. Many modifications and other embodiments of the disclosure will come to mind to one skilled in the art to which this disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. The embodiments described herein are meant to be illustrative and are not intended to be limiting. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. The invention is not limited in its application to the details of the construction and to the arrangement of the components set forth in the above description or as illustrated in the drawings. While it has 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.