Abstract:
A method for reducing the coefficient of friction of an archery arrow&#39;s shaft to ease the retrieval of the arrow from an archery target. The method includes covering the shaft between the ferrule and fletching with a PTFE-based lubricating material, buffing the lubricant to a uniform thickness along the arrow shaft and heating the lubricated shaft to set the PTFE to the arrow shaft.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of United States Provisional Patent Application filed Jun. 13, 2007 having Ser. No. 60/943,728. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to archery and, more particularly, to a method for coating arrow shafts to ease retrieval of arrows from archery targets. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Currently, archers have difficulty in extracting their arrows from a target. This is particularly so when dense closed-cell targets are used. These targets receive and expand around the arrow shaft and due to the high degree of friction of the cellular material along with the high penetration depths achieved by modern bows, pulling an arrow from such a target can be extremely difficult. 
     Retrieving such a stuck arrow therefore requires the user to use a relatively large amount of force to pull these “stuck” arrows from a target. If care is not taken retrieving these arrows, however, the user can possibly either injure himself or damage either the arrow or the target. It should be appreciated that even the slightest bend or curve made into an arrow shaft can cause great in-flight inaccuracy. 
     The broad purpose of the present invention is to provide a safe and easy process for reducing the coefficient of friction of the outer surface of an arrow shaft. 
     Prior art attempts to reduce the friction between the arrow and target involve the repeated application of a silicone-containing liquid to the arrowhead and the front portion of the arrow shaft. One example of such a prior art method is disclosed in U.S. Pat. No. 6,093,685 issued to Gary L. Wood, Sr. on Jul. 25, 2000. This patent discloses a liquid-based silicone lubricant that is applied with either a dauber or by dipping an arrow into a lubricant containing vessel. This method of lubricating an arrow, however, suffers from the drawback of having to repeatedly reapply the lubricant while shooting. Additionally, after reapplying the liquid, the archer must then wait for the liquid to dry prior to shooting. 
     The present invention overcomes the above-referenced and other disadvantages of prior art techniques for easing the retrieval of arrows from a target by semi-permanently applying a lubricant material upon the outer surface of the arrow&#39;s shaft. This lubricant material includes a solid particulate material having a very low coefficient of friction which is suspended in a semi-fluid paste or wax. By buffing and/or heating the lubricant material, the user can ensure the non-stick material is fixed to the shaft. 
     The present invention provides a novel method of lubricating an arrow that conditions the arrow&#39;s shaft using a polytetrafluoroetylene (PTFE) based solid lubricant, such as the materials sold under the trademarks Teflon and Zonyl by the E. I. Du Pont De Nemours and Co., Corporation. This lubricant is applied suspended within a thin layer of paste, wax or colloid (e.g., a sol gel) onto an arrow shaft. In the preferred embodiment, heat is applied to the lubricant-coated arrow to aid in drying and speeding the set-up of the lubricant to the shaft. In one embodiment the lubricant is rubbed or buffed onto the arrow shaft. 
     It is an advantage of the present invention to provide a method for easily retrieving arrows from an archery target, the method including the steps of providing a PTFE-based lubricant, applying the lubricant to an arrow shaft, and heating the lubricant to set the lubricant upon the shaft. 
     It is another advantage of the present invention that the PTFE in the lubricant can be sintered to the outer surface of an arrow shaft by heating the coated arrow shaft. 
     It is still another advantage of the present invention that a PTFE-based lubricant is applied to the arrow shaft to ensure that the lubricating material is both non-reactive and that the high-temperatures of the arrow head and shaft entering a target do not melt or degrades the lubricant. 
     It is yet another advantage of the present invention that an arrow shaft having microscopic cracks and fissures in its outer surface that is lubricated according to the present invention, will have the cracks and fissures filled and smoothed by the lubricant. 
     It is still yet another advantage of the present invention that the lubricated arrow shaft reduces friction losses and noise as the arrow slides along the arrow rest. 
     It is still yet another advantage of the present invention that the lubricated arrow shaft reduces in-flight drag of the arrow. 
     Still further objects and advantages of the invention will become readily apparent to those skilled in the art to which the invention pertains upon reference to the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description refers to the accompanying drawings in which like reference characters refer to like parts throughout the several views; and in which: 
         FIG. 1  is a graphical representation of the method steps used to lubricate an arrow shaft. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIG. 1 , a preferred method of lubricating the outer surface  10  of the shaft  12  of an archery arrow  14  is shown. As will be discussed further below, a lubricant material  16  is applied to arrow shaft  12 , which is then heated to set or fix the material  16  upon the shaft  12 . Arrow shaft  12  can be substantially any conventional archery arrow shaft, including aluminum, graphite, carbon fiber, or wood. 
     Lubricant material  16  is preferably a wax, paste or colloidal sol which suspends and contains microscopic, 2-20 μm, particles of lubricating solids  18 , such as polytetrafluoroethylene (PTFE). The binder material  19  (e.g., wax) is preferably a low-cost shelf stable material which readily accepts the lubricating solid particles  18 . In the preferred embodiment, the lubricating solid  18  comprises 0.5-5% of the lubricant material  16  by weight. 
     While PTFE is preferred due to its very low coefficient of friction and non-reactivity, it should be appreciated that other lubricating solids can be used in material  16 . PTFE is also preferable due to the high melting temperature of approximately 620° F. This high melting point allows for a relatively high operating temperature range such that any heat encountered by the arrow  14  will not affect the lubricating properties of material  16 . 
     One example of how a lubricant having a high operating temperature has advantages over other lubricants like silicone is that metal arrowheads and broadheads generate a great deal of friction as they enter conventional archery targets, particularly closed-cell foam archery targets. This friction quickly generates heat which passes through the broadhead, into the ferrule, and down the arrow shaft. This is particularly so, if the arrow shaft is made of a conductive material like aluminum. This heat may breakdown, degrade, or otherwise melt other lubricant materials, which would prevent the lubricant from performing its intended purpose of easing the retrieval of the arrow from the target. Further, this thermal breakdown of the lubricant will necessitate reapplication of the lubricant to the arrow. 
     In one embodiment of the invention, binder material  19  and particulates  18  are first wiped onto arrow shaft  12 . The lubricant  16  is preferably applied along the outer surface  12  of the arrow shaft  12  between the ferrule  20  (i.e., the front of the shaft having means for attaching the arrowhead) and the fletching  22 . Then buffing means  24 , such as a mechanical buffing wheel or a simple cloth, is used to repeatedly pass over the outer surface  10  of the arrow shaft  12 . This buffing operation ensures that the lubricant material  16  is applied as a relatively thin uniform layer  28  which is thoroughly applied to shaft  12  and also fills any microscopic cracks, pits, or fissures in the shaft  12  with the material  16 . 
     This buffing process typically generates heat, which in addition to the physical removal or wiping away of excess material  16  causes binder  19  to at least partially melt/evaporate to leave a thin layer  28  of material  16  upon surface  10 . This thin layer  28 , while still retaining the low-friction particulates  18  and exhibiting the low coefficient of friction of these particulates, does not greatly increase the weight of arrow  14  or cause imbalance issues for arrow  14 . 
     In another non-limiting embodiment, the lubricating particles  18  are sintered to the arrow shaft  12 . This process of sintering the lubricating solid to outer surface  14  is preferably achieved by heating the particles  18  to just below their melting temperature, such that the particles bond together in an around the arrow. For a PTFE-based lubricant  16 , this temperature may be approximately 600° F. In one non-limiting embodiment, such a process may be accomplished with a conventional heat gun  30  or through a conventional oven-based heat treating process. In this embodiment, the wax or paste binder  19  retaining the solid particles  18  will melt away and leave the now-sintered non-stick material  18  upon the shaft  12 . 
     From the foregoing description, one skilled in the art will readily recognize that the present invention is directed to a method for conditioning an arrow shaft to ease removal of the arrow from an archery target. While the present invention has been described with particular reference to various preferred embodiments, one skilled in the art will recognize from the foregoing discussion and accompanying drawings that changes, modifications and variations can be made in the present invention without departing from the spirit and scope thereof.