Patent Application
20060085961
The present invention relates generally to archery bows and more particularly pertains to an improved method and apparatus for manufacturing archery risers.
A compound archery bow typically comprises a riser, bow limbs, and a bowstring. Archery risers are sometimes referred to as the handle portion of an archery bow, although more precisely a handle portion is part of or connected to a riser frame. Typically upper and lower bow limbs extend from the riser with a bowstring or cable between the limb tips. When the bowstring is drawn, the bow limbs are flexed to store energy. When the bowstring is released, the stored energy propels the arrow. In conventional compound bows, one end of each limb is attached to the bow riser or handle and a rotational member such as a wheel, cam or pulley is mounted on the other end.
There are currently different methods of manufacturing an archery riser. One such method involves machining the archery riser from a solid piece, for example an aluminum billet, by removing material to leave a desired profile and shape. Another method involves die-casting the archery riser using a mold assembly. In another method the archery riser is extruded into the desired profile and shape. The operations are generally costly, mechanically complex, time consuming, and result in a waste of material.
There is a need for an improved method to manufacture archery risers.
In preferred embodiments, the present invention is concerned with a method and apparatus for manufacturing an archery riser.
A preferred embodiment of the present invention involves a method for manufacturing an archery riser for an archery bow, involving providing a flat workpiece and forming the flat workpiece to a pre-bent profile of an archery riser. The method further involves placing the flat workpiece in a press and bending the flat workpiece to a desired non-flat shape of the archery riser. In one embodiment, the flat workpiece is an aluminum material in a T4 aluminum condition. After forming the workpiece to a non-flat shape, the workpiece can optionally be cured to a hardened state, such as a T6 aluminum condition.
Another preferred method according to the present invention forms an archery riser for an archery bow by providing a flat stock to be formed into an archery riser, cutting the flat stock to a profile defining the approximate pattern of the archery riser, placing the flat stock in a press assembly, and compressing the flat stock in the press assembly to form a desired non-flat shape of the archery riser. Preferably the flat stock is one portion of an aluminum sheet. Further, the aluminum sheet can be divided into two or more portions in order to form two or more archery bow risers.
A further preferred method of the present invention involves a method of manufacturing an archery riser for an archery bow. The method comprises providing a flat stock of aluminum material in a first state to be manufactured into an archery riser, forming the flat stock to a desired pre-bent profile of an archery riser, and providing a die defining a cavity. The cavity has a first surface forming a first shape defining a first riser side to be manufactured and a second surface forming a second shape defining a second riser side to be manufactured. Further steps of a preferred method include placing the flat bar stock in the cavity of the die and pressing the die to change the pre-bent profile of the flat bar stock into a desired non-flat shape of the archery riser conforming to the first and second riser sides.
It is an object of this invention to provide an improved method of manufacturing an archery riser for an archery bow.
Other objects and attendant advantages of this invention will be readily appreciated as the same become more clearly understood by references to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof.
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.
A method according to the present invention forms an archery riser for use in an archery bow. A preferred method comprises providing a flat workpiece, forming the flat workpiece to a pre-bent profile of an archery riser, placing the flat workpiece in a press, and bending the flat workpiece to a non-flat shape of the archery riser. Preferably the flat workpiece is an aluminum material in a relatively soft, flexible condition. After forming the workpiece to a non-flat shape, the workpiece can optionally be cured to a more hardened state.
Bowstring 44 includes upper end 38 and lower end 40 which are fed-out from pulleys 26 and 28 when the bow is drawn. The extended cable portions of bowstring 44 are mounted around pulleys 26 and 28 as is known in the art.
When the bowstring 44 is drawn, it causes eccentric pulleys 26 and 28 at each end of the bow to rotate, feeding out bowstring cable while limb portions 22 and 24 are bent inward, causing additional energy to be stored therein. When the bowstring 44 is released with an arrow engaged to the bowstring, the limb portions 22 and 24 return to their rest position, causing the eccentric pulleys 26 and 28 to rotate in the opposite direction, to take up the bowstring 44 and launch the arrow with an amount of energy proportional to the energy initially stored in the bow limbs. Bow 10 is described for illustration and context and is not intended to be limiting. The present invention can be used in conjunction with dual-cam compound bows, or can be used in conjunction with single-cam bows as described for example in U.S. Pat. No. 5,368,006 to McPherson, hereby incorporated herein by reference, or can be used in other pulley/cam arrangements. The present invention can also be used in conjunction with other types of bows, which are considered conventional for purposes of the present invention.
The flat workpiece 50 is preferably an aluminum alloy. Aluminum alloys can include temper designations. Aluminum alloy products which are thermally treated are typically designated with a “T” temper designation. A T4 temper designation indicates that the aluminum alloy has been solution heat treated and naturally aged. A T6 temper designation indicates that the aluminum alloy has been solution heat treated and then artificially aged. A T6 aluminum alloy is in a more hardened state than a T4 aluminum alloy. Therefore, processes often involve allowing an aluminum alloy to naturally age to a T4 condition and then artifically aging the alloy to a T6 condition. In a preferred embodiment, the flat workpiece 50 is a solid piece of aluminum alloy material in a T4 condition. An aluminum workpiece in a T4 condition is in a softer, more flexible condition and thus better suited for the method of the present invention, being less likely to shatter, lose strength, and/or become more brittle during application in a die press or similar machine than a material in a more hardened state. However, it should be appreciated that other appropriate materials may be used as the flat workpiece 50 as would occur to one skilled in the art.
To begin the manufacturing process of an archery riser, a flat or pre-bent pattern or profile 60 of an archery riser is formed from the flat workpiece 50. In a preferred embodiment, the pre-bent profile 60 is cut or ground using a cutting head or laser from the flat workpiece 50 using a computerized numerically controlled (“CNC”) process. However, it should be understood that other processes can be used to form the pre-bent profile 60 as would generally occur to one skilled in the art.
When the pre-bent profile 60 is in a suitable condition to be bent or shaped, it is inserted into a press assembly 70, as illustrated in
As illustrated in
Placing the pre-bent profile 60 in the press assembly 70 in a first orientation and compressing the pre-bent profile 60 creates a shaped archery riser 80 appropriate for a right-handed archery bow. Preferably, placing the pre-bent profile 60 in the press assembly 70 in a second orientation, and compressing the pre-bent profile 60 creates a shaped archery riser 80 appropriate for a left-handed archery bow. In one embodiment, the first orientation is a first side contacting the upper die member 72 and a second side contacting the lower die member 74, and the second orientation is the first side contacting the lower die member 74 and the second side contacting the upper die member 72. Thus, optionally the same press assembly 70 may be used to create both left-handed and right-handed shaped archery risers 80.
Further, slight adjustments and finishing can be made to the shaped archery riser 80 by any appropriate method as would generally occur to one skilled in the art. In one embodiment, the edges of the shaped archery riser 80 are machine ground to smooth the edges and to make any necessary adjustments. Crafting the exact desired profile and shape of the archery riser may also involve forming rounded corners and radiused edges. Additionally, after the shaped archery riser 80 has been formed, holes are often drilled in the shaped archery riser 80 to remove weight or for mounting sights and other accessories of an archery bow. The shaped archery riser 80 can be polished, decorated or otherwise enhanced by methods that would generally occur to one skilled in the art and then incorporated into an archery bow.
After being formed into a bent profile, the shaped archery riser 80, still in a T4 aluminum condition, may be cured to a T6 aluminum condition if desired or necessary. This will cause the shaped archery riser 80 to assume a more hardened state than the T4 aluminum condition, as discussed above. In one embodiment, the shaped archery riser 80 is cured by being placed in an oven not to exceed 350 degrees Fahrenheit for a period of approximately 6 hours.
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.
