Abstract:
A golf club with a new innovative construction to attach a high density weight to an external surface of the sole of a golf club head is disclosed herein. More specifically, the present invention relates to utilizing a thickened sole portion having a specific surface area to thickness ratio to provide adequate support for a high density weight having a significant amount of mass. The new innovative method of attachment also incorporates a unique mechanical lock to properly secure the high density weight to the club head, as materials used for high density weighting may not be easily weldable to the titanium material currently used for metalwood type golf club head. The present invention&#39;s mechanical lock mechanism utilizes a protruding extension stemming from an internal surface of the weight and an attachment socked located within an internal cavity of the golf club head to engage one another to help secure the weight to the golf club head.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to an innovative construction to attach high density weights to a golf club head. More specifically, the present invention relates to an innovative construction to attach high density weights to an external surface of a golf club head wherein the materials used for the high density weight doesn&#39;t lend itself well to the traditional attachment method of welding. 
       BACKGROUND OF THE INVENTION 
       [0002]    Ever since the golf industry has shifted away from persimmon wood type golf clubs into the modern metal wood type golf clubs, golf club engineers have always tinkered with the weight distribution of the golf club head in order to improve the performance of the golf club head. Because the modern day metal wood golf clubs are generally made out of a lightweight titanium type of material, they may not be able to shift a significant amount of weight around the golf club head. In order to address the weighting deficiencies of titanium, golf club engineers have attempted to attach higher density metallic materials to the body of the titanium golf club head. 
         [0003]    U.S. Pat. No. 4,824,110 to Kobayashi shows one of the earlier attempts at combining different materials having different specific gravity to form a golf club head in order to adjust the weighting distribution of the golf club head. Moreover, U.S. Pat. No. 4,824,110 focuses on the usage of fiber reinforced plastic as the lightweight material while using traditional titanium or steel as the heavy weighted material. Although the usage of fiber reinforced plastic is one way to achieve significant discretionary weight within a golf club head, it does so at the expense of some other performance characteristics such as the sound of the golf club at impact. 
         [0004]    Despite all of the design advantages associated with the fiber reinforced plastic, the usage of completely metallic golf club head is still preferred by much of the golfing public for its superior sound characteristics. The problem with the titanium material used to create a metal wood type golf club head is that it may not always join well together with materials such as tungsten, molybdenum, or zirconium; all of which have a higher density than titanium. U.S. Pat. No. 5,935,019 to Yamamoto recognizes this issue and identifies this issue by saying that “it is difficult to weld together metals of different types, and especially difficult when one of the metal is titanium or a titanium alloy.” U.S. Pat. No. 5,935,019 addresses this bonding issue by forming a metallic hollow golf club head with a sole plate molded form a light metal and formed with a fitting hole, and a weighted structure comprising a weight of a heavy metal press-fitted into a ring-shaped spacer formed of the same light metal as the sole plate, said weighted structure being fitting into the fitting hole, and the ring-shaped spacer and the sole plate being welded together. 
         [0005]    U.S. Pat. No. 6,379,265 to Hirakawa et al. illustrates another attempt to joint two metallic materials together in a golf club head to improve the performance. More specifically, U.S. Pat. No. 6,379,265 illustrates a metal wood club including a sole plate and a weight body which is fastened to this sole plate via a spacer. A recess which accommodates the spacer and weight body is formed in a portion of the sole plate, and undercut part is formed in the inside circumferential portion of the recess, and a circumferential groove is formed in the outer circumferential portion of the weight body. When the weight body is press-fitted in the recess with the spacer in between, the spacer is forcibly engaged with the undercut part and circumferential groove, thus allowing the weight body to be firmly fastened to the recess of the sole plate of the club head. 
         [0006]    Despite all of the attempts to attach high density weights to a metallic golf club head, most of these attempts utilize crude press-fitting techniques that do not allow the materials to bond together in a clean fashion. Moreover, the press-fitting techniques discussed above do not help limit the relative rotation of the heavy density weight with respect to the golf club head, which could lead to undesirable rattling. Hence, it can be seen from above there is a need in the field for a golf club head that is capable of joining together a heavy density metallic material together with a lower density metallic material in a manner that not only provides a clean and aesthetically pleasing joint, but also in a way that prohibits the rotation and vibration of the weight itself. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In one aspect of the present invention is a hollow metalwood type golf club head comprising a striking face portion, a body portion, a thickened sole portion, and a weight. The striking face portion is located at a frontal portion of the golf club head. The body portion is connected to an aft portion of the striking face portion. The thickened sole portion is connected to a sole cavity of the body portion, wherein the thickened sole portion has a surface area to thickness ratio of less than about 1000.0 mm; the surface area to thickness ratio is defined as the surface area of the thickened sole portion divided by a thickness of the thickened sole portion. The weight is attached to an external surface of the thickened sole portion. The golf club head has a density ratio of greater than about 2.0, wherein the density ratio is defined as a density of the weight divided by a density of the body portion. Finally, the attachment of the weight to the thickened sole portion utilizes a mechanical lock. 
         [0008]    In another aspect of the present invention is a hollow metalwood type golf club head comprising a striking face portion, a body portion, a thickened sole portion, and a weight. The striking face portion is located at a frontal portion of the golf club head. The body portion is connected to an aft portion of the striking face portion. The thickened sole portion is connected to a sole cavity of the body portion. The weight is attached to an external surface of the thickened sole portion. The attachment of the weight to the thickened sole portion utilizes a mechanical lock, wherein the mechanical lock further comprises a protruding extension stemming from the weight, and an attachment socket located within an internal cavity of the golf club head, adapted to engage the protruding extension; wherein the protruding extension and the attachment socket engages one another to secure the weight to the thickened portion of the golf club head. 
         [0009]    In a further aspect of the present invention is a hollow metalwood type golf club head comprising a striking face portion, a body portion, a thickened sole portion, and a weight. The striking face portion is located at a frontal portion of the golf club head. The body portion is connected to an aft portion of the striking face portion. The thickened sole portion is connected to a sole cavity of the body portion, wherein the thickened sole portion has a surface area to thickness ratio of less than about 1000.0 mm; the surface area to thickness ratio is defined as the surface area of the thickened sole portion divided by a thickness of the thickened sole portion. The weight is attached to an external surface of the thickened sole portion, wherein the weight has a mass of between about 10 grams to about 40 grams. Finally, the attachment of the weight to the thickened sole portion utilizes a mechanical lock. 
         [0010]    These and other features, aspects and advantages of the present invention will become better understood with references to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. 
           [0012]      FIG. 1  shows a perspective view of a golf club head in accordance with an exemplary embodiment of the present invention; 
           [0013]      FIG. 2  shows an exploded perspective view of a golf club head in accordance with an exemplary embodiment of the present invention; 
           [0014]      FIG. 3  shows a sole view of a golf club head in accordance with an exemplary embodiment of the present invention illustrating cross-sectional line A-A′; 
           [0015]      FIG. 4  shows a cross-sectional view of a golf club head in accordance with an exemplary embodiment of the present invention, taken along cross-sectional line A-A′ shown in  FIG. 3 ; 
           [0016]      FIG. 5  shows a cross-sectional view of a golf club head in accordance with an alternative embodiment of the present invention, taken along cross-sectional line A-A′ shown in  FIG. 3 ; 
           [0017]      FIG. 6  shows a perspective view of a snap ring used in accordance with an alternative embodiment of the present invention; 
           [0018]      FIG. 7  shows an exploded perspective view of a mechanical lock attachment mechanism in accordance with an exemplary embodiment of the present invention; and 
           [0019]      FIG. 8  shows an assembled perspective view of the mechanical lock attachment mechanism in accordance with an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0021]    Various inventive features are described below that can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any or all of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below. 
         [0022]      FIG. 1  of the accompanying drawings shows a perspective view of a golf club head  100  in accordance with an exemplary embodiment of the present invention. More specifically,  FIG. 1  of the accompanying drawings shows the golf club head  100  being constructed out of four different components, a striking face portion  101 , a body portion  102 , a thickened sole portion  104 , and a weight  106 . The usage of the four different components within this current exemplary embodiment of the present invention is generally used to allow the current golf club head  100  to incorporate a weight  106  at a strategic location identified in  FIG. 1 . In order to understand the proper functionality of the four different components, and the reason to have the four different components, it is worthwhile to begin a discussion about the material properties of each of the components. 
         [0023]    Like previously mentioned, the modern age metal wood type golf club head may generally be constructed out of a titanium material, to which it is difficult to weld any high density materials. Following that theme, the body portion  102  of the golf club head  100  in accordance with the current exemplary embodiment may generally be constructed out of a lightweight titanium type material for its high strength and low weight properties. The titanium material used to construct the body portion  102  may generally have a density of about 4.5 g/cc; however numerous other types of metallic material with high strength-to-weight ratio could be used without departing from the current scope and content of the present invention so long as they have a density of between about 4.0 g/cc and about 5.0 g/cc. 
         [0024]    Weight  106 , as discussed in this current exemplary embodiment of the present invention, may generally be made out of a material that has a higher density than the titanium material used to construct the body portion  102  in order to provide a more noticeable change to the weighting properties of the golf club head  100 . More specifically, weight  106  may generally be constructed out of a tungsten type material have a density of about 17.0 g/cc; however numerous other materials such as molybdenum, zirconium, tantalum, brass, copper, gold, or even platinum could all be used without departing from the scope and content of the present invention so long as they have a density that is greater the density of the body portion  102  of the golf club head  100 . Alternatively speaking, the material used for the weight  106  may generally have a density of greater than about 9.0 g/cc, more preferably greater than about 9.5 g/cc, and most preferably greater than about 10.0 g/cc all without departing from the scope and content of the present invention. 
         [0025]    Given the need of the weight  106  to dramatically change the weighting properties of the golf club head  100 , the requirement that the density of the weight  106  be greater than about twice that of the density of the body portion  102  will generally yield a “density ratio” of greater than about 2.0, more preferably greater than about 2.1, most preferably greater than about 2.2. The density ratio, as referred to in the current exemplary embodiment of the present invention, is defined by Equation (1) below: 
         [0000]    
       
         
           
             
               
                 
                   
                     Density 
                      
                     
                         
                     
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                     Ratio 
                   
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                       Density 
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                       of 
                        
                       
                           
                       
                        
                       Weight 
                        
                       
                           
                       
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                         ( 
                         106 
                         ) 
                       
                     
                     
                       Density 
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                       of 
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                       Body 
                        
                       
                           
                       
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                       Portion 
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                         ( 
                         102 
                         ) 
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
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                     ( 
                     1 
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         [0026]    Finally, the golf club head  100  shown in  FIG. 1  also incorporates a thickened sole portion  104 . Because the overall mass of the weight  106  is so high relative to the portion of the golf club head  100  that it is attached to, combined with the fact that it is generally desirable to keep the wall thickness of the body  102  as thin as possible to reduce unnecessary weight; the thinned body portion  102  may generally lack sufficient thickness to support the mass of weight  106 . Hence, in order to increase the stability of the attachment of the weight  106  to the golf club head  100 , a thickened sole portion  104  is created to reinforce the interface between the weight  106  and the body portion  102 . 
         [0027]    The thickened sole portion  104 , as discussed in this current exemplary embodiment of the present invention, may generally be formed out of the same material as the material used to form the body portion  102  of the golf club head. Having the thickened sole portion  104  formed out of the same material as the body portion  102  allows for the two components to be attached easily to one another using traditional attachment methodologies such as welding. However, thickened sole portion  104  may be formed out of a material that is substantially similar to, or completely different from the body portion  102  material without departing from the scope and content of the present invention, so long at the materials can be easily joined together. 
         [0028]      FIG. 2  of the accompanying drawings that shows an exploded view of the golf club head  200  to provide a better illustration of the relationship amongst the various components. In addition to the golf club head  200 , the body portion  102 , the thickened sole portion  204 , and the weight  106 ,  FIG. 2  also shows a locking nut  208  and a sole cavity  210 . This exploded view also illustrates how the weight  206  incorporates a protruding extension  207  that extends into the internal cavity of the golf club head  200  to engage a locking nut  208  to form a “mechanical lock”. It is worth noting here that the material used to form the locking nut  208  may generally be titanium, as it is a material that can be easily welded and joined to the thickened sole portion  204 ; however, the locking nut  208  may also be formed out of an alternative material without departing from the scope and content of the present invention so long as it is formed out of a material that can easily bond to the base material of the thickened sole portion  204 . The usage of this mechanical lock is important to the proper functionality of the current invention because, as previously mentioned, the material used to create the weight  206  may not join well to the material used to form the remainder of the body portion  202 . 
         [0029]    Locking nut  208 , as shown in  FIG. 2  of the accompanying drawings, may generally refer to one part of the “mechanical lock” that works in conjunction with the protruding extension  207  of the weight  206  to secure the weight  206  to the thickened sole portion  204 . In fact, in a more general term, the locking nut  208  may be referred to as an attachment socket to refer to any other types of attachment mechanism that completes the “mechanical lock” without departing from the scope and content of the present invention. However, due to the extreme impact conditions a golf club head  200  experiences during impact with a golf ball, the mere threaded locking connection between the locking nut  208  and the protruding extension  207  may become lose through time; resulting in a weight  206  that can easily fall apart from the golf club head  200 . The current invention, in order to further strengthen the connection and bond between the weight  206  and the actual club head  200 , has made the locking nut  208  out of the same material as the remainder of the body portion  202  and the thickened sole portion  204 . Having the locking nut  208  made out of the same material as the remainder of the golf club head  200  allows the locking nut  208  to be welded to the remainder of the thickened sole portion  204 , further increasing the bond strength of the weight  206  to the golf club head  200 . 
         [0030]    It is worth re-emphasizing here that the implementation of the mechanical lock together with a weldable locking nut  208  is only necessary because the weight  206  itself can not be easily welded together, requiring the addition of these mechanical components. The current invention, in order to create sufficient bond strength, utilizes both a mechanical lock mechanism with titanium components to allow welds to be used to accomplish a secure bond between the golf club head  200  and the high density weight  206 . 
         [0031]    Finally,  FIG. 2  of the accompanying drawings shows an opening on the sole of the golf club head  200 , to which the thickened sole portion  204  may generally be attached to the body  202  of the golf club head  200 . The opening created by the sole cavity  210 , may generally have a geometry that substantially matches the geometry of the thickened sole portion  204  to allow the thickened sole portion  204  to cover up the sole cavity  210 . The bond between the thickened sole portion  204  and the body portion  202  may generally be accomplished via conventional welding techniques, as the discussion above has already indicated that both components are made out of generally the same weldable material such as titanium. 
         [0032]      FIG. 3  of the accompanying drawings shows a sole view of a golf club head  300  in accordance with an exemplary embodiment of the present invention. The sole view of the golf club head  300  shown in  FIG. 3  allows cross-sectional line A-A′ to be shown, from which a cross-sectional view can be created in  FIG. 4 . 
         [0033]      FIG. 4  of the accompanying drawings provide a cross-sectional view of the golf club head  400  taken along cross-sectional line A-A′ shown in  FIG. 3 . More specifically, the cross-sectional view of golf club head  400  shows how the body portion  402 , the thickened sole portion  404 , the weight  406 , and the locking nut  408  all interface with one another to complete the golf club head  400 .  FIG. 4  shows that the thickened sole portion  404  may generally have a wall thickness that is significantly thicker than the thickness of the remainder of the body portion  402 , despite the fact that both of these components may be made out of the same material. The purpose of increasing the thickness of the thickened sole portion  404  is to provide more structural rigidity to the portion of the golf club head  400  that the weight  406  attaches to. The minimal thickness d 1  of the thickened sole portion  404  in this current exemplary embodiment of the present invention may generally be greater than about 1.60 mm, more preferably greater than about 1.65 mm, and most preferably greater than about 1.70 mm. However, the absolute thickness d 1  of the thickened sole portion  404  may not be indicative of the requisite thickness for the thickened sole portion  404 ; due to the fact that the thickness required may generally be a function of the surface area of the thickened sole portion  404  itself. Hence, in order to more precisely quantify the thickness requirement of the thickened sole portion, a surface area to thickness ratio is defined below by Equation (2): 
         [0000]    
       
         
           
             
               
                 
                   
                     Surface 
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                     Area 
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         [0000]    The surface area to thickness ratio of the thickened sole portion  404  in accordance with the current exemplary embodiment of the present invention may generally be less than about 1000.0 mm, more preferably less than about 969.0 mm, and most preferably less than about 941.0 mm; with the total surface area of the thickened sole portion being approximately 1600 mm 2 . 
         [0034]    Like prior discussions have indicated, the weight  406  used in this current exemplary embodiment of the present invention may generally be constructed out of a heavy weight high density material that carries significant mass. More specifically, the weight  406  discussed in this current invention may generally have a mass of between about 10 grams and about 40 grams, more preferably between about 15 grams and about 25 grams, and most preferably about 20 grams. Having such a heavy weight  406  may generally mean that the momentum generated by the weight  406  during a golf swing could cause significant stress on the attachment mechanism. Hence, in order to ensure that the weight  406  is securely attached to the golf club head  400 , all while preserving the minimal amount of weight for the remainder of the golf club head  400 , the present invention has constructed a thickened sole portion  404  to which the weight  406  can easily attach. 
         [0035]      FIG. 4  of the accompanying drawings also shows the interface amongst all of the components of the mechanical lock, including the weight  406  and the locking nut  408 . Although not shown in detail,  FIG. 4  of the accompanying drawings is intended at showing that the protruding extension  407  and the locking nut  408  engage one another using threads. Although these types of threaded mechanical lock may generally be the preferred mechanical lock methodology, it is not the only type of mechanical lock that can be used. In fact, other types of mechanical locks such as dovetails, undercuts, wedge fits, press fits, or even spring fits may be used without departing from the scope and content of the present invention so long as it provides a mechanically lock that secures the weight  406  to the club head  400 . 
         [0036]      FIG. 5  of the accompanying drawings shows a cross-sectional view of a golf club head  500  in accordance with an alternative embodiment of the present invention, taken along the same cross-sectional line A-A′ shown in  FIG. 3 . The alternative embodiment of the present invention shown in  FIG. 5  utilizes a different “mechanical lock” mechanism to secure the weight  506  to the golf club head  500 . More specifically, the “mechanical lock” mechanism shown in this embodiment may generally comprise of a weight socket  512  having locking channel  516 , a protruding extension  507  having a complimentary channel  517 , and a snap ring  514 . The locking channel  516  of the weight socket  512  encircles the protruding extension  507  of the weight  508  to work in conjunction with a complimentary channel  517  formed on the protruding extension  507  to create an oversized channel around the weight  506 . To complete the “mechanical lock” a snap ring  514  is wedged in between the locking channel  516  and the complimentary channel  517 , securing the weight  506  to the body portion  502  of the golf club head  500 . The snap ring  514  shown in this current exemplary embodiment of the present invention may generally be a metallic ring that expands to allow the weight  506  to be inserted into the weight socket  512 , and contracts to prevent any outward movement of the weight  506 . 
         [0037]    Similar to the locking nut  208  shown above in  FIG. 2 , the weight socket  512  may also be referred to more generally as an attachment socket that engages the protruding extension  507  to secure the weight  506  to the club head  500  without departing from the scope and content of the present invention. 
         [0038]      FIG. 6  of the accompanying drawings shows an enlarged perspective view of the snap ring  614  in accordance with an exemplary embodiment of the present invention, as the snap ring  514  in  FIG. 5  was too small to show sufficient detail. The snap ring  614  may generally have an opening  615  near one of its circular ends, allowing the snap ring  614  to increase and decrease its inner diameter to hold the weight  506  within it&#39;s place within the golf club head  500 . (both shown in  FIG. 5 ) More information regarding the basic functionality of a snap ring can be found in U.S. Pat. No. 7,090,061, the disclosure of which is incorporated by reference in its entirety. 
         [0039]      FIG. 7  of the accompanying drawings show an enlarged exploded perspective view of the weight  706 , the thickened sole portion  704 , and the locking nut  708 . This exploded view shown in  FIG. 7  allows an “anti-rotation components” between the weight  706  and the thickened sole portion  704  to be shown with more clarity. More specifically, the “anti-rotation components” shown in this exemplary embodiment of the present invention includes an oversized base  720  at the base of the protruding extension  707  and an opening  722  on the thickened sole portion  704 , which work in conjunction with one another to prohibit the rotation of the weight  706 , once it is attached to the thickened sole portion  704 . The oversized base  720  and its congruently shaped opening  722  work together to further strengthen the mechanical lock created by the threaded protruding extension  707  and the locking nut  708  by limiting the relative rotation of one component from the other, which can cause any threaded mechanical lock to become loose. Although the shape of the oversized base  720  is shown to be square in shape, oversized base  720  can be rectangular, octagonal, hexagonal, polygonal, or it can take on any other shape that contains a corner to prohibit the rotation of the weight  706  relative to the thickened sole portion  704  without departing from the scope and content of the present invention. 
         [0040]    In addition to the “anti-rotation components” used to enhance the bond of the mechanical lock between the weight  706  and the thickened sole portion  704 ,  FIG. 7  of the accompanying drawings shows a plurality of weld grooves  724  located at the terminal end of the protruding extension  707  that can also be used to enhance the bond. The plurality of weld grooves  724 , as shown in the current exemplary embodiment of the present invention, may generally provide a channel or groove for the weld beads to run longitudinally from one end of the protruding extension  707  to another end of the protruding extension  707 , strapping the locking nut  708  to the thickened sole portion  706 . Because rotational mechanical locks such as the threaded mechanism shown in  FIG. 7  could easily loosen itself when subjected to numerous impact vibrations, the added plurality of weld grooves  724  strengthens that bond by further limiting the rotation of the locking nut  708  relative to the weight  706 . 
         [0041]    The integration of the plurality of weld grooves  724  into the thickened sole portion  704  and the locking nut  708  can be shown more clearly in  FIG. 8  of the accompanying drawings, providing an assembled perspective view of the weight  806 , thickened sole portion  804 , and the locking nut  808 . More specifically, it can be seen that once the entire weight assembly is put together, the plurality of weld grooves  824  can be seen to extend out from the locking nut  808 , allowing the weldable components to be welded together to complete the attachment of the weight  806  to the thickened sole portion  804 . 
         [0042]    Other than in the operating example, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, moment of inertias, center of gravity locations, loft, draft angles, various performance ratios, and others in the aforementioned portions of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear in the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. 
         [0043]    Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting form the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used. 
         [0044]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the present invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.