Abstract:
A metal wood golf club head having a faceplate which is first cast or forged then CNC (computer numerical control) milled to a controlled thickness to form a precisely configured faceplate optimizing the sweet spot.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates generally to a metal wood golf club head, and more particularly, to a metal wood golf club head having a faceplate which is first cast or forged then CNC (computer numerical control) milled to a controlled thickness to form a precisely configured faceplate optimizing the sweet spot.  
           [0003]    2. Description of the Related Art  
           [0004]    Golf club manufacturers have over the years made new and different designs for golf clubs to improve a golfer&#39;s performance. Different materials including metals for the “woods” have been used to increase ball flight distance and improve the feel of the club. Various weighting schemes, including perimeter weighting, have been proposed to optimize the center of gravity and moment of inertia of club heads. More recently, oversized club heads have been utilized to attempt to provide a large sweet spot on the ball striking face.  
           [0005]    Perhaps the most important factor in hitting a golf ball well is the location of impact of the ball on the striking surface of the faceplate. A ball which is hit in the center of the sweet spot will generally go farther and straighter than a ball impacting near the heel or toe of the faceplate. A ball hitting face with a controlled thickness, and more particularly, a ball hitting face with its thickest region concentrated in the middle of the face, is desirable for achieving an efficient energy transfer to the golf ball and for providing a ball striking surface with greater strength and stability. One design of a metal wood golf clubs known in the art having a variable faceplate thickness is described in U.S. Pat. No. 5,474,296.  
           [0006]    There is however a need for a method of making a golf club head having a face with controlled thickness to provide the required strength and stability, which is accurate and flexible to accommodate the need to achieve and/or change the desired thickness.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    The present invention provides a method of fabricating a metal wood golf club head with a controlled thickness faceplate and a golf club head made according to the method. The faceplate with a controlled thickness according to the present invention is accomplished by CNC milling the backside of the faceplate concentrically about a circular of oval shaped sweet spot at the center of the faceplate.  
           [0008]    The faceplate of the present invention has a central portion with the maximum thickness and a peripheral portion with a reduced thickness. The reduction of thickness from the central portion to the peripheral portion is made gradually and accurately using the CNC milling process. The thickened central portion enables an efficient energy transfer upon impact with the golf ball without compromising the stability and weight balance of the club head.  
           [0009]    The above described and many other features and attendant advantages of the present invention will become apparent from a consideration of the following detailed description in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    A detailed description of the invention will be made with reference to the accompanying drawings wherein:  
         [0011]    [0011]FIG. 1 is a perspective view of the golf club head of the present invention;  
         [0012]    [0012]FIG. 2 is a view of the front of the faceplate of the golf club head of FIG. 1  
         [0013]    [0013]FIG. 3 is a cross-sectional view taken along lines  3 - 3  of FIG. 2;  
         [0014]    [0014]FIG. 4 is a cross-sectional view showing the backside of the faceplate; and  
         [0015]    [0015]FIG. 5 is an exploded perspective view of the golf club head according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    FIGS.  1 - 5  show a golf club head  10  in accordance with the present invention. The golf club head  10  is assembled from a sole plate  12 , a faceplate  14 , a top plate  16  and a hosel  18 ; the sole plate  12  has a rear wall portion  20 , a toe portion  22  and a heel portion  24 . The hosel  18  is positioned in the hollow interior of the golf club head at the joint between the heel portion  24  of the sole plate  12  and to faceplate  14  and is formed and placed in the club head to receive a golf club shaft. The hosel  18  is preferably aligned with or offset from the center of gravity of the club head  10 . The materials used to form the components of the club head  10  include steel, stainless steel, titanium, and other metallic materials having similar or better strength and resilience properties.  
         [0017]    The backside  28  of the faceplate  14  of the golf club head  10  as shown in FIG. 2 has a central portion  30  as indicated by the circle, and a peripheral portion  32 . The central portion  30  is the area that has the maximum cross-sectional thickness on the faceplate  14 . In one embodiment of the present invention, the thickness in the central portion  30 , the area within the circle, is uniform and is between about 2.5 mm to 5 mm and optimally about 3.0 mm as indicated at T 1  in FIG. 3. The thickness from the radial edge of the central portion  30  to the peripheral portion  32  is gradually decreased so that the thickness in the thinnest portion T 2  of the peripheral portion  32  reduces by between 0.25 mm and 1.5 mm, and by way of example for a optimal thickness of 3 mm at T 1 , T 2  is about 2.5 mm in FIG. 3.  
         [0018]    The faceplate  14  with controlled thickness according to the present invention is prepared utilizing the CNC milling technique. The faceplate  14  is first formed by either forging or casting. Such processes are well known in the art. In one embodiment of the invention, the faceplate  14  is slightly convex and the front side of the faceplate  14  has a plurality of horizontal grooves  34 . The horizontal grooves  34  are designed to provide improved traction upon impacting a golf ball as well as an improved feel when the golf club head impacts a golf ball. The backside of the faceplate  14  is CNC milled to provide the central portion  30  with a greater thickness compared to that of the peripheral portion  32 , effectively making the club face with a controlled thickness. The CNC milling technique is used to cut and achieve the exact dimensions of thickness at a given point of the club face  14 . The circular marks  38  on the backside of the club face outside of the central portion  30  in FIG. 2 show the cuts resulting from the CNC milling process.  
         [0019]    There are many advantages of having a variable thickness club face prepared according to the present invention. First, the CNC milling technique provides the desired precision and flexibility. Unlike other golf clubs made by a standard molding process, the CNC milling process can be programmed to change and obtain the desired thickness at a given area of the club face without having to construct new physical structures, i.e. making a new mold to accommodate a change in thickness, thereby reducing the operational costs, and providing the ease and ability to make golf clubs with different club face thickness. Second, the golf club head made according to the present invention can remain well balanced since no bulging weight or additional metal is added on the rear side of the club face as shown in other clubs known in the art. Thus, the present invention provides a well-balanced golf club head to enhance a golfer&#39;s performance. The golf club of the present invention also provides an extremely efficient energy transfer to a golf ball at the point of impact. Using the CNC milling, different portions of the club face can be easily made to have different thickness, and the process essentially enables one to make a club face with the desired stress pattern. Varying the thickness in the central portion  30  compared to that of the peripheral portion  32 , has the effect of concentrating more metal within that central portion and providing greater impact strength.  
         [0020]    The golf club head of the present invention is made by forging or casting each of the sole plate  12 , the faceplate  14  and top plate  16 . Generally, the faceplate  14  will be forged or cast so as to have an approximately constant thickness even though the striking surface is slightly convex. The hosel  18  is either cast, rolled or cut from a tube.  
         [0021]    The faceplate  14  is then placed in a CNC mill machine wherein the backside  28  of the faceplate  14  is CNC milled. While the shape of the cuts made by the CNC machine as depicted in the figures appended hereto show a circular cut pattern, it should be understood that other noncircular cut patterns could be used. Thus, an oval shaped cut pattern having a long axis extending from the toe toward the heal may be preferred, alternatively, the cut pattern could have a roughly triangular shape or a shape generally matching the shape of the striking surface of the faceplate  14 , as long as the approximate center of the pattern is positioned at an optimal point within the sweet spot for any particular club head design. By providing for uniformity in the decrease in the thickness around the periphery of the sweet spot while maintaining the preferred thickness within the sweet spot, the club head according to the present invention will have a more uniform trampoline effect when striking the ball.  
         [0022]    After the backside  28  of the faceplate  14  is CNC milled, the faceplate  14  is attached to the sole plate  12  by welding. The hosel  18  is then attached to the faceplate  14  and to the sole plate  12  by spot welding. Next, the top plate is attached to the sole plate  12  and the faceplate  14  by welding. To finish the club head, a mill or grinding wheel is used to mill or grind off welds on the outside of the assemble club head. Finally the assembled club head is powder coated and/or painted.  
         [0023]    Having thus described different embodiments of the invention, other variations and embodiments that do not depart from the spirit of the invention will become readily apparent to those skilled in the art. The scope of the present invention is thus not limited to any one particular embodiment, but is instead set forth in the appended claims and the legal equivalents thereof.