Patent Publication Number: US-7721403-B2

Title: Manufacturing method for a golf club head

Description:
This application is a Continuation of co-pending Application Ser. No. 11/118,356, filed on May 2, 2005, now abandoned which is a Divisional of Application Ser. No. 10/725,544, filed on Dec. 3, 2003 and now abandoned, and for which priority is claimed under 35 U.S.C. § 120; the entire contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a golf club head. In particular, the present invention relates to a golf club head that is produced by means of joining two portions of the golf club head by friction welding. 
     2. Description of Related Art 
     A typical golf club head and a production method therefore are disclosed in, e.g., U.S. Pat. Nos. 5,769,307 and 5,885,170. As illustrated in  FIGS. 1 and 2  of the drawings which respectively correspond to  FIGS. 1 and 2  of U.S. Pat. Nos. 5,769,307 and 5,885,170, a typical golf club includes a head body  10 , a hosel  20 , and a shaft  30 . The head body  10  is made of a metal material and includes a striking plate  11  on a front side thereof, with a heel  12  being formed on a side of the striking plate  11 , and with an extension  13  extending upward from the heel  12  and having a flat abutting portion  131 . Another flat abutting portion  22  is formed at a lower part of the hosel  20  that is formed of another metal material. The hosel  20  includes an engaging hole  21  in an upper part thereof for engaging with a lower end of a shaft  30 . 
     A force F is applied to the head body  10  and the hosel  20  to make the flat abutting portion  131  abuts against the flat abutting portion  22 . Then, the flat abutting portion  131  (or the flat abutting portion  22 ) is turned relative to the flat abutting portion  22  (or the flat abutting portion  131 ). With the friction heat, the head body  10  can be joined to the hosel  20 . 
     Although the friction welding simplifies the manufacturing process and cuts the manufacturing cost in comparison to ordinary welding or brazing, several problems exist. Firstly, the metal material of the flat abutting portion  131  and the metal material of the flat abutting portion  22  melt and fuse with each other after friction welding, forming an intermetallic layer (not shown). Since the metal material (e.g., stainless steel) of the flat abutting portion  131  differs from that (e.g., titanium alloy) of the flat abutting portion  22  and thus provides poor compatibility in welding, the metallurgic structure of the intermetallic layer is detrimental to improvement of the bonding strength, resulting in a fragile structure or reducing the resilient deforming capability. As a result, the connection area between the head body  10  and the hosel  20  may break when proceeding with adjusting of inclination angle A of the hosel  20  of the golf club head product or when striking a golf ball. The good product ratio is reduced, and the life of the club head is shortened. Results of cannon shot tests showed that the head body  10  and the hosel  20  were apt to crack or break after being shot not more than 1000 times (a golf ball with a standard weight hits the striking plate  11  of the head body  10  at a velocity of 50 m/sec). The same problem exists when using friction welding to bond two portions of the club head that are made of different metals having insufficient compatibility. 
     OBJECTS OF THE INVENTION 
     An object of the present invention is to provide an intermediate layer for joining two portions of a golf club head by friction welding, providing improved joining reliability, improving good product ratio, and prolonging the life of the golf club head product. 
     Another object of the present invention is to provide an intermediate layer for joining a head body and a hosel of a golf club head by friction welding, providing improved joining reliability for the hosel, improving adjusting range of the inclination angle of the hosel, and prolonging the life of the golf club head product. 
     A further object of the present invention is to provide an intermediate layer for joining a head body and a weight member of a golf club head by friction welding, providing improved joining reliability for the weight member. 
     SUMMARY OF THE INVENTION 
     In accordance with an aspect of the present invention, a golf club head includes a first portion forming a part of a head body of the golf club head, a second portion forming another part of the head body of the golf club head, and an intermediate layer. The first portion, the second portion, and the intermediate layer are made of different materials. Each of the first portion and the second portion has an abutting portion, with the intermediate layer being positioned between the abutting portion of the first portion and the abutting portion of the second portion. The intermediate layer and the abutting portion of the first portion are joined together by welding friction, and the intermediate layer and the abutting portion of the second portion are joined together by friction welding, thereby forming a golf club head product. 
     The metallurgical compatibility between the first metal material and the third metal material is better than that between the first metal material and the second metal material, and the metallurgical compatibility between the second metal material and the third metal material is better than that between the first metal material and the second metal material. 
     In an embodiment of the invention, the first portion is a head body, and the second portion is a hosel. The bonding strength and bonding reliability of the golf club head product are improved by the intermediate layer. Further, subsequent adjustment of the inclination angle of the hosel is convenient, and the life of the golf club head product is prolonged. In another embodiment of the invention, the first portion is a head body, and the second portion is a weight member. 
     Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is an exploded perspective view of a conventional golf club head; 
         FIG. 2  is a sectional view illustrating formation of the conventional golf club head by friction welding; 
         FIG. 3  is an exploded perspective view of a first embodiment of a golf club head in accordance with the present invention; 
         FIG. 4  is a sectional view illustrating formation of the golf club head in  FIG. 3  by friction welding; 
         FIG. 5  is a perspective view of the golf club head in  FIG. 3 ; 
         FIG. 6  is an exploded perspective view of a second embodiment of the golf club head in accordance with the present invention; 
         FIG. 7  is a sectional view illustrating formation of the golf club head in  FIG. 6  by friction welding; 
         FIG. 8  is an exploded perspective view of a third embodiment of the golf club head in accordance with the present invention; 
         FIG. 9  is a sectional view illustrating formation of the golf club head in  FIG. 8  by friction welding; 
         FIG. 10  is an exploded perspective view of a fourth embodiment of the golf club head in accordance with the present invention; 
         FIG. 11  is a perspective view illustrating formation of the golf club head in  FIG. 10  by friction welding; and 
         FIG. 12  is a perspective view of the golf club head in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Preferred embodiments of the present invention are now to be described hereinafter in detail, in which the same reference numerals are used in the preferred embodiments for the same parts as those in the prior art to avoid redundant description. 
     Referring to  FIG. 3 , a first embodiment of a golf club head in accordance with the present invention includes a first portion, a second portion, and an intermediate layer  40 . In this embodiment, the first portion is a head body  10  made of a first metal material. A string plate  11  is formed on a front side of the head body  10  for striking a golf ball. A heel  12  is formed on a side of the striking plate  11 , with an extension  13  extending upward from the heel  12  and having an abutting portion  131 . 
     The second portion is a hosel  20  having an engaging hole  21  in an upper part thereof for engaging with a shaft  30 . The hosel  20  further includes an abutting portion  22  formed at a lower part thereof. The hosel  20  is made of a second metal material. The intermediate layer  40  is made of a third metal material. The first metal material, the second metal material, and the third metal material are different from one another. The metallurgical compatibility between the first metal material and the third metal material is better than that between the first metal material and the second metal material. Further, the metallurgical compatibility between the second metal material and the third metal material is better than that between the first metal material and the second metal material. Given that the first metal material is different from the second metal material, each of the first metal material and the second metal material is selected from the group consisting of stainless steel, titanium alloy, carbon steel, low-alloy steel, cast iron, nickel-base alloy, structural steel, Fe—Mn—Al alloy, and super alloy. The third metal material is selected from the group consisting of niobium (Nb), chromium (Cr), aluminum (Al), iron (Fe), zirconium (Zr), titanium (Ti), vanadium (V), tantalum (Ta), silver (Ag), nickel (Ni), tungsten (W), and alloys thereof. The shaft  30  can be made of other metal material or a non-metal material, such as carbon fiber composite material. 
     Referring to  FIGS. 4 and 5 , the head body  10  (the first portion), the intermediate layer  40 , and the hosel  20  (the second portion) are joined together by friction welding. In assembly, a force F is applied to the head body  10  and the hosel  20  to make the abutting portion  131  of the head body  10 , the intermediate layer  40 , and the abutting portion  22  of the hosel  20  abut against each other in sequence. Then, the abutting portion  131  is turned relative to the abutting portion  22  and the intermediate layer  40 . With the friction heat, the abutting portion  131  is joined to the intermediate layer  40 . 
     Next, the abutting portion  22  (or the combination of the abutting portion  131  and the intermediate layer  40 ) is turned relative to the combination of the abutting portion  131  and the intermediate layer  40  (or the abutting portion  20 ). With the friction heat, the abutting portion  22  is joined to the combination of the abutting portion  131  and the intermediate layer  40 . Thus, the head body  10 , the intermediate layer  40 , and the hosel  20  are joined together. A golf club head product is obtained after removal of residuals. 
     Referring to  FIG. 4 , since the intermediate layer  40  is made of a third material having a better welding compatibility with the abutting portion  131  made of the first material and the abutting portion  22  is made of the second material, the bonding strength of the two abutting portions  131  and  22  is improved via provision of the intermediate layer  40  between the abutting portions  131  and  22 . Results of cannon shot tests showed that the head body  10  and the hosel  20  neither cracked nor broke after being shot not more than 1000 times (a golf ball with a standard weight hits the striking plate  11  of the head body  10  at a velocity of 50 m/sec). The bonding strength and bonding reliability of the golf club head product are improved by the intermediate layer  40 . Further, subsequent adjustment of the inclination angle A of the hosel  20  is convenient, and the life of the golf club head product is prolonged. 
     The intermediate layer  40  can be formed in the shape of a tablet in advance. Alternatively, the intermediate layer  40  can be powdery or pasty or can be provided on the abutting portion  131  and/or the abutting portion  22  by electroplating or spraying. Further, the surface roughness of the abutting portion  131  and/or the abutting portion  22  is smaller than Ra 25 μm, preferably smaller than Ra 6.3 μm, and most preferably smaller than Ra 1.6 μm. By this arrangement, when the abutting portion  131  and/or the abutting portion  22  abuts against the upper side of the intermediate layer  40  and/or the lower side of the intermediate layer  40 , the oxidized layer (not shown) on the contacting area is scraped by the surface roughness. Thus, adverse effects to the bonding strength and bonding reliability by the oxidized layer is avoided. 
       FIGS. 6 and 7  illustrate a second embodiment of the present invention, wherein the abutting portion  131  of the head body  10  (the first portion) includes an annular wall  132  delimiting a space (not labeled) for receiving the intermediate layer  40  that is tablet-like, powdery, or pasty. Alternatively, the intermediate layer  40  is provided by electroplating or spraying. The annular wall  132  allows precise alignment between the head body  10  (the first portion), the intermediate layer  40 , and the hosel  20  (the second portion). After friction welding, the annular wall  132  can be kept or removed by proper surface finishing, providing a golf club head product (see  FIG. 5 ). 
       FIGS. 8 and 9  illustrate a third embodiment of the present invention, wherein the abutting portion  22  of the hosel  20  (the second portion) includes an annular wall  23  delimiting a space (not labeled) for receiving the intermediate layer  40  that is tablet-like or pasty. Alternatively, the intermediate layer  40  is provided by electroplating or spraying. The annular wall  23  allows precise alignment between the head body  10  (the first portion), the intermediate layer  40 , and the hosel  20  (the second portion). After friction welding, the annular wall  23  can be kept or removed by proper surface finishing, providing a golf club head product (see  FIG. 5 ). 
       FIGS. 10 through 12  illustrate a fourth embodiment of the present invention, wherein the intermediate layer  40  is used to join the head body  10  (the first portion) and a weight member  50  (the second portion). The head body  10  includes a compartment  14  in an appropriate portion thereof (such as the bottom side of the head body  10 ). A bottom wall delimiting the compartment  14  forms an abutting portion  141 , and the weight member  50  includes an abutting portion  51  on a side thereof. The intermediate layer  40  is tablet-like, powdery, or pasty. Alternatively, the intermediate layer  40  is provided on the abutting portion  141  of the compartment  14  by electroplating or spraying. 
     The head body  10  and the weight member  50  are joined together via the intermediate layer  40  by friction welding under the condition of applying a force F to the head body  10  and the weight member  50 . A golf club head product (see  FIG. 12 ) is obtained after removal of residuals on the weight member  50 . In this embodiment, the first metal material is selected from the group consisting of stainless steel, carbon steel, titanium alloy, low-alloy steel, cast iron, nickel-base alloy, structural steel, Fe—Mn—Al alloy, and super alloy. The second metal material is a material having a specific density greater than 7.6 g/cm 3  and selected from the group consisting of W—Fe—Ni alloy, tungsten alloy, molybdenum (Mo) alloy, and copper alloy. The material for the intermediate layer  40  is selected from the group consisting of niobium (Nb), chromium (Cr), aluminum (Al), iron (Fe), zirconium (Zr), titanium (Ti), vanadium (V), tantalum (Ta), silver (Ag), nickel (Ni), tungsten (W), and alloys thereof. 
     While the principles of this invention have been disclosed in connection with specific embodiments, it should be understood by those skilled in the art that these descriptions are not intended to limit the scope of the invention, and that any modification and variation without departing the spirit of the invention is intended to be covered by the scope of this invention defined only by the appended claims.