Abstract:
A method of making a golf club head and the head itself which club head has two or more portions. Each portion comprises metals of differing characteristics. One portion may be made of ductile metal to facilitate bending.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Golf club iron heads including hosels have been made of high strength titanium alloys. Such heads have for reasons of “feel” and scratch resistance been favored. However, such head hosel portions have lacked ductility to be readily adjusted by bending for loft and lie angle adjustment without an unacceptable failure rate. Lower strength titanium, such as unalloyed titanium, irons have less favorable “feel” and scratch resistance but have improved ductility for hosel bending for loft and lie angle adjustment.  
         SUMMARY OF THE INVENTION  
         [0002]    Broadly, the present invention is a method of creating a golf club head in which two or more head portions of differing material are fabricated and thereafter joined to form the complete club head. The hosel and the adjacent head portion subject to strain when the club head is adjusted is composed of a ductile material while the remaining head portion is comprised of strong abrasion-resistant material.  
           [0003]    Preferably both portions are titanium or titanium alloys. In particular, commercially pure titanium is useful for the club head portion which will be stressed and distorted to achieve adjustment and a titanium-aluminum-vanadium high strength alloy for the remainder of the head. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]    [0004]FIG. 1 is a front elevational view of a golf club head with a partial view of the shaft attached;  
         [0005]    [0005]FIG. 2 is an exploded elevational view of a club head composed of two portions;  
         [0006]    [0006]FIG. 3 is an elevational view of the two head portions of FIG. 2 joined together;  
         [0007]    [0007]FIG. 4 is an elevational view of a club head composed of three portions;  
         [0008]    [0008]FIG. 5 a  is a front elevational view of the head including the hosel; and  
         [0009]    [0009]FIG. 5 b  is a front elevational view of the head and hosel after bending to increase loft. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0010]    The method of the present invention involves fabrication of two or more portions of a club head followed by joining the portions together to form a complete head including a hosel. An iron head includes three portions which are the (1) ball-striking body portion (2) the hosel which receives the shaft and (3) the transition or neck portion between portions (1) and (2). In particular, the method permits casting the hosel-transition portion and ball-striking body of a golf iron head of differing materials and, in particular, differing titanium-containing materials.  
         [0011]    In a preferred embodiment of the invention, the club head portion comprising the hosel-transition portion is formed of a titanium-base alloy material which is low strength and ductile such as commercially pure titanium which has minor amounts of trace elements i.e. 1% or less. The remaining head portion, herein also referred to as the “body”, is cast of a high strength alloy of titanium. Titanium having aluminum and vanadium as alloying elements is preferred. High strength alloys have aluminum in the range of 2.5%-6.75% by wt. and vanadium in the 2% to 4.5% by wt. range. In particular, such alloys include titanium —6Al—4V in which aluminum is 5.5 to 6.75% by wt. and vanadium is 3.5 to 4.5% by wt. with the remainder being titanium with minor amounts of trace elements of 1% or less. Another high strength alloy is Ti-3-2.5 in which aluminum is 2.5 to 3.5% by wt. and vanadium 2.0 to 3.0% by wt. with remaining material being titanium with minor amounts of trace elements i.e. 1% or less.  
         [0012]    The hosel, including transition portion, and the body are separately produced using investment casting techniques and the two (2) parts are thereafter joined by electron beam welding or other suitable welding or other joining technique. The head may also be made of three or more portions. For example, (1) the ball-striking body portion and (2) the hosel, including transition portion. Since the hosel transition or neck portion is where bending takes place it should be made of a ductile titanium material. Additionally, (3) a third portion comprised of a high density material may be located so as to adjust center of gravity and moment of inertia of the golf clubs as an insert  25  in the sole of the club head (see dotted lines in FIG. 3).  
         [0013]    Turning to FIGS. 1, 4,  5   a  and  5   b,  golf club  10  includes head  11  and shaft  12 . Shaft  12  is inserted into and secured to hosel  14 . Head  11  also includes body  16  having ball striking face  17 , toe  18  and sole  20 . Further shown is hosel-adjacent portion  15  which portion is between hosel  14  and face  17 . With respect to FIGS. 2 and 3, body portion  22  is shown fabricated as a separate part and positioned in exploded view for attachment to the hosel-transition part  23  which hosel-transition part  23  includes hosel  24  and transition portion  26 . In FIG. 3 the two parts are shown joined along joint line  28 . In FIG. 4, another embodiment is shown in which body  22 ′, transition portion  26 ′ and hosel  24  are each fabricated as separate parts and thereafter joined as two weldments. Bending normally takes place in the location of the club head at or on either side of plane BA (see FIG. 2).  
         [0014]    When a golf club is bent, both the body of the club head and the hosel are torqued one relative to the other. The transition or neck portion of the club is most stressed and deformed to allow the body and hosel to move relative to one another to accomplish the adjustment such as changing the loft angle The stressed volume of material comprising the transition or neck  15 ,  26  which is distorted extends from the front of the club head to the back of the club head. Distortion is caused to take place at the specific portion of the club&#39;s head neck area including hosel-adjacent portion  15  or transition portion  26  as the body and upper area of the hosel are restrained from distortion.  
       EXAMPLE 1  
       [0015]    Body portion  22  was formed by investment casting of an alloy of titanium-aluminum-vanadium in which the titanium was nominally 90% and a second portion  23  consisting of hosel  24  and hosel-transition portion  26  was also formed by investment casting of commercially pure titanium metal (see FIG. 2). Portions  22  and  23  were joined along weld line  28  (see FIG. 3) to form club head  30 .  
         [0016]    In order to increase the loft of club head  30  body portion  22  and hosel weld  24  were subjected to a torque which caused bending. The loft was increased 1% as shown by angle A (see FIGS. 5 a  and  5   b ). No cracking or failure was observed.  
       EXAMPLE 2  
       [0017]    The fabrication of a club head was repeated as described in Example 1 above.  
         [0018]    Head  11  has a lie angle (the angle between the shaft and the ground (G) which may be decreased or increased by bending: The lie angle after bending is angle B on FIG. 1.  
         [0019]    No cracking or failure was observed.