The present invention relates generally to the field of arrow shafts.
Archery arrows with graphite or “composite” shafts are gaining in acceptance. Graphite shafts have reduced weight plus generally greater flex and strength than traditional materials. Traditionally however, graphite shafts have suffered from inconsistent manufacturing, higher costs, a soft feel and higher breakage rates. Composite graphite shafts have normally been made by either a sheet-rolling method or a filament winding method.
In the sheet-rolling or sheet-wrapping method, carbon, glass or other fibers are impregnated with a plastic resin and placed in a parallel matrix to form a broad sheet or prepreg. The prepreg is then cut into smaller sheets with all of the fibers at a particular angle to the axis of the intended mandrel, the angle can be between 0° and 90°. These flags are then rolled around a mandrel to form various layers or plies. The layers are then cured to form a composite and the mandrel is removed.
In the filament winding method, fibers are collected into groups called “tows” and each tow is impregnated with resin and wrapped around the mandrel to form the layers prior to curing. Filament winding generally results in an improved shaft with greater consistency in manufacture and control of fiber placement.
Archery is generally used for hunting or target shooting. Various colors and patterns for arrows are sometimes desired. Arrows can be decorated using regular patterns for a desired ornamental look or irregular patterns such as camouflage patterns. Typical methods of imparting color and patterns to graphite arrow shafts include painting the material or wrapping the shaft in a tight-fitting, decorated material, for example a shrink-wrap film or decal. A film or decal may leave visible seams in the pattern. In an alternate method, some manufacturers have embedded a decorated material in a prepreg sheet to be wrapped in the outer layer around a shaft; however, this option is not available in filament winding. In some instances, the shafts are encased in a protective transparent mask or film after the decoration is added. These shafts are vulnerable to the outer decorative patterns being worn away or damaged for example due to heat and friction or scratches after a period of use.
In one embodiment of the present invention, a method is disclosed of making an arrow shaft having multiple graphite plies. The method includes forming an arrow shaft core of one or more filament wound or sheet-rolled fiber reinforced graphite plies around a mandrel. A first filament wound ply including at least a first color is wound around the core. A second filament wound ply including at least a second color differing from the first color is wound around the core and the first ply. The first filament wound ply and the second filament wound ply form an arrow shaft outer layer with a thickness and having an outer diameter equal to or greater than the desired shaft finished outer diameter. The shaft is then finished, including removing the mandrel from the shaft, and defining an arrowhead mounting portion and a nocking point portion on the shaft.
In another embodiment of the present invention, a method is disclosed of making an arrow shaft having multiple graphite plies. The method includes winding filaments including at least a first color around a mandrel, and wrapping filaments of at least a second color differing from the first color around the mandrel. The filaments are incorporated in the thickness of an arrow shaft, and the first color and the second color create a color pattern extending through at least a substantial portion of the thickness of the shaft. The shaft is then removed from the mandrel, and an arrowhead mounting portion and a nock mounting portion are on the defined shaft.
In yet another embodiment of the present invention, a composite arrow shaft is formed from multiple fiber reinforced graphite plies forming a core for an arrow shaft having two ends. The core is formed of one or more filament wound or sheet-rolled fiber reinforced graphite plies; and an outer layer is formed of at least one ply filament wound around the core to form an arrow shaft with a desired total diameter. The outer layer preferably includes filaments of at least two different colors. The shaft includes an arrowhead mounting section at one end of the shaft and a nocking section at the opposing end of the shaft.
In yet another embodiment of the present invention, a composite arrow shaft with a length is formed from multiple fiber reinforced graphite plies. The shaft is formed with one or more filament wound plies, and includes a first filament wound portion including filaments of a first color, and a second filament wound portion including filaments of a second color. Preferably the first color is different from the second color.
It is an object of the invention to provide an improved arrow shaft.
Further objects, features and advantages of the present invention shall become apparent from the detailed drawings and descriptions provided herein.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations, modifications, and further applications of the principles of the invention being contemplated as would normally occur to one skilled in the art to which the invention relates.
In certain preferred embodiments, the present invention provides arrow shafts and a method of making arrow shafts with two or more colors. Preferably the shafts incorporate filament winding using two or more colors to leave two or more visible colors in the finished shaft in a multi-colored regular or irregular pattern. Preferably the multi-colored pattern extends a substantial distance through the thickness of the shaft.
The present invention provides an improved archery arrow shaft formed with an elongated body using a combination of fiber-reinforced graphite composites. A typical arrow 8 made in accordance with the present invention is illustrated in
“Graphite” or “composite” herein are intended to have their art recognized meanings, generally including fibers in a resin material. The fibers are typically made of graphite, carbon, glass, boron, synthetic fibers such as Kevlar®, fiberglass or other conventional materials, and are made individually in filament form to create a filament tow, or in a parallel resin matrix to form a sheet or prepreg.
Some graphite arrows are made using a sheet-rolling process, such as is illustrated in
The angle of the fibers in a ply can range from 0° to 90° from the longitudinal axis of the mandrel. Intermediate angles in sheet-rolled plies are generally balanced with a ply having fibers angled in the opposite direction. Flags with longitudinal fibers (0°) generally have more effect on flex and bending strength, while fibers with higher angles generally have more effect on torque. Once a sufficient number of layers are applied, the shaft is cured and sanded for finishing. Shafts made with sheet-rolling alone are often criticized as mechanically inconsistent, for example for including seams where sheets overlap, which can cause inconsistent radial stiffness.
Filament wrapping, as illustrated in
The size and spacing of tows in
After a tow is wound one direction on a shaft, traditionally the angle of winding and direction is reversed so that a particular layer or ply may have windings at opposite angles as shown in
One example of a hybrid composite, illustrated in
As illustrated in cross-section in
In certain preferred embodiments, the shaft includes filament wound plies in outer layer 25 having two or more colors. By way of further illustration,
A further embodiment of a shaft 10″ is illustrated with a portion in
In certain preferred embodiments, the two or more colors visible on the outer surface of the shaft extend a substantial distance through the thickness of the shaft between the outer diameter OD and inner diameter ID. For example, the color pattern may extend through the thickness of outer layer 25, and may optionally extend through the entire thickness of shaft 10, being incorporated into the outer layer 25 and the core 20, if a core is present.
As each ply is filament wound onto the shaft, it creates a pattern of peaks and valleys. A combination of multiple filament wound plies creates an interference pattern of overlapping peaks and valleys. The interference pattern may result in an uneven outer diameter surface which may partially show each color which has been wound. To remove and minimize the uneven outer diameter, the shaft is sometimes built to a larger outer or “sacrifice” diameter than is ultimately desired, and is later finished, for example, by curing, grinding and/or sanding to the desired outer diameter and weight. As one example, the sacrifice layer may be approximately 10% larger than the desired final shaft outer diameter. One method of grinding or finishing uses a centerless grinder moving in a direction opposite the shaft rotation and which traverses the length of the shaft.
The grinding and sanding step removes a portion of the thickness of outer layer 25 to leave a desired, preferably substantially smooth, outer diameter with a resulting color pattern. In some embodiments, shown for example in
In still further alternate embodiments, shown with arrows 8′ and 8″ in
In additional alternate embodiments, arrow shafts made in accordance with the present invention take advantage of properties provided by metal-coated fibers. The metal coatings may be the same color or different colors from the graphite fibers. All or a portion of the fibers in the may be metal coated. Examples of coating metals which may be used on fibers include: nickel, titanium, platinum, zinc, copper, brass, tungsten, cobalt, gold and silver. In addition to different visual effects and colors, various metals, such as copper and nickel, have varying attributes and are used in different proportions to provide different degrees of weight, strength, and vibration absorption. The metal coating may be vapor deposited on the fibers; alternately the metal coating may be electroplated onto the fibers. The metal coating may bond to the fibers or form sheaths around them. By way of illustration, the metallic coating may have a thickness between 400 Angstroms and 2.5 microns depending on the desired weight and appearance.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.