Patent Publication Number: US-2005143190-A1

Title: Golf club and method for manufacturing same

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a golf club and a method for manufacturing the same.  
      2. Description of the Related Art  
      As a conventional technique, Japanese Unexamined Patent Publication No. 11-4922 discloses a golf club which has a head body, the head body is made from, for instance, soft iron such as S20C, titanium, titanium alloy, wherein a weight which is made from tungsten alloy, stainless steel, copper alloy, etc., is fitted into the head body or a piece which is made from titanium, aluminum etc., is fitted into a face thereof.  
      Recently, in order to obtain a high-performance golf club by setting a more difference in specific gravity, one which has a weight made from tungsten alloy fitted thereinto has been marketed. In general, a tungsten-alloy-made piece is made by sintering, but it has little ductility, and thus a plastic deformation thereof by caulking itself is difficult. Accordingly, in the present circumstances, the tungsten-alloy-made piece is joined by screwing, bonding, caulking by a plastic deformation of the head body. For screwing and bonding, a side of the tungsten-alloy-made piece is machined straightly. However, since tungsten alloy contracts about 20%, a dimensional accuracy thereof is to be rough, and thus machining at a machining center or the like is required. Moreover, a side face of the head body for receiving the tungsten-alloy-made piece is also formed with a straight concaved portion, and the tungsten-alloy-made piece is fitted thereinto.  
      However, no matter how much machining accuracy is improved, a slight gap is unavoidably created since there is a tolerance in machining between the head body and the tungsten-alloy-made piece. Moreover, machining cost is expensive. Further, even though a caulking is applied to the head body, it is still difficult to prevent the creation of the gap when dimensional accuracy is not high.  
      The slightest gap can cause various problems. For instance, joining strength is to be inferior, misalignment is caused when hitting a golf ball, and a separation of the tungsten-alloy-made piece is resulted from that misalignment at worst. Moreover, a polishing agent used for buffing or the like enters the gap and it may ooze later on. When the head body is made from soft iron, plating is required, and thus a plating solution or a pre-process solution may enter the gap. It often results in defective plating.  
     SUMMARY OF THE INVENTION  
      The present invention has been made to solve those problems. It is, accordingly, an object of the present invention to provide a golf club having a head made from a plurality of metallic members, the head comprising: one member concavely formed with a receiving portion thereon; and the other member fitted into the receiving portion so as to be integrated with each other, wherein the golf club enables the reduction of as much machining cost as possible and have no gap.  
      The other object thereof is to provide a method for manufacturing the same.  
      In order to attain the above objects, according to a first aspect of the present invention, there is provided a golf club comprising: a head made of a plurality of metallic members; and a shaft connected to the head, the head comprising: one member formed with a receiving portion; and an other member fitted into the receiving portion so as to be integrated with each other, wherein: an inner circumference of the receiving portion is tapered so as to allow a width thereof to be gradually wider from a bottom portion toward an aperture portion thereof; an outer circumference of said other member is tapered so as to allow a width thereof to be gradually wider from a rear portion toward a front portion thereof; and a depth of the receiving portion is defined so as to be slightly larger than a thickness between the front portion and the rear portion.  
      According to the first aspect of the present invention, if the one member and the other member are preliminary tapered by molds or the like so that their taper angles are substantially equal, the other member can be fitted into the receiving portion in a manner dropping into the recess portion of the one member without processing.  
      Alternatively, in the above-described golf club, the width of the front portion of the other member may be substantially equal to the width of the aperture portion of the receiving portion; and a taper angle of the inner circumference may be substantially equal to a taper angle of the outer circumference.  
      Moreover, in the above-described golf club, the one member may be a head body connected to the shaft; the receiving portion may be formed on a region of the head body corresponding to a face thereof; and the other member may be a face member.  
      Further, the one member and the other member may be made from different metals, respectively.  
      Still further, the other member may be made from metal having larger specific weight than that of the one member.  
      In order to attain the above objects, according to a second aspect of the present invention, there is provided a method for manufacturing a golf club, the golf club comprising: a head made of a plurality of metallic members; and a shaft connected to the head, the head comprising: one member formed with a receiving portion; and an other member fitted into the receiving portion so as to be integrated with each other, wherein the method comprising steps of: forming an inner circumference of the receiving portion to be tapered so as to allow a width thereof to be gradually wider from a bottom portion toward an aperture portion thereof; forming an outer circumference of the other member to be tapered so as to allow a width thereof to be substantially equal to the width of the aperture portion and gradually wider from a rear portion toward a front portion thereof; defining a depth of the receiving portion to be slightly larger than a thickness between the front portion and the rear portion; and fitting the other member into the receiving portion in a manner dropping into the recess portion of the one member toward the recess portion of the receiving portion via a clearance between the rear portion and the recess portion.  
      According to the second aspect of the present invention, if the one member and the other member are preliminary tapered by molds or the like so that their taper angles are substantially equal, the other member can be fitted into the receiving portion in a manner dropping into the recess portion of the one member without processing.  
      Alternatively, in the above-described method, the one member may be a head body connected to the shaft; the receiving portion may be formed on a region of the head body corresponding to a face; and the other member may be a face member.  
      Moreover, the one member and the other member may be made from different metals, respectively.  
      Further, the other member may be made from metal having larger specific weight than that of the one member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These objects, other objects and advantages of the present invention will become more apparent upon reading of the following detailed description and the accompanying drawings in which:  
       FIG. 1  is a perspective view illustrating a golf club according to a first embodiment of the present invention;  
       FIG. 2  is a cross sectional view illustrating the golf club of the first embodiment;  
       FIG. 3  is an exploded view illustrating the golf club of the first embodiment;  
       FIG. 4  is a perspective view illustrating a golf club according to a second embodiment of the present invention;  
       FIG. 5  is a cross sectional view illustrating a golf club of the second embodiment;  
       FIG. 6  is an exploded view illustrating the golf club of the second embodiment;  
       FIG. 7  is a cross sectional view illustrating a portion of the golf club on larger scale;  
       FIG. 8  is a cross sectional view illustrating a golf club according to a third embodiment of the present invention;  
       FIG. 9  is an exploded view illustrating the golf club of the third embodiment;  
       FIG. 10  is a cross sectional view illustrating a golf club according to a fourth embodiment;  
       FIG. 11  is a perspective view illustrating the golf club of the fourth embodiment;  
       FIG. 12  is a cross sectional view illustrating a golf club according to a fifth embodiment; and  
       FIG. 13  is a bottom plan view illustrating the golf club of the fifth embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.  
      FIGS.  1  to  3  illustrate a first embodiment. A golf club of the present invention comprises a shaft  1  provided with a grip (not illustrated) on an upper end thereof, and a head  2  connected to a lower end of the shaft  1 . The head  2  is formed with a hosel  3  on one side thereof as a shaft connecting portion protruding from the one side, a face  4  on a front side thereof, a sole  5  on a lower portion thereof, respectively. The head  2  having the hosel  3 , the face  4  and the sole  5  comprises: a head body  7  as one member concavely formed with a receiving portion  6  on a rear side thereof; and a weight  8   w  as the other member of tabular fitted into the receiving portion  6 . The head body  7  is made of an iron-based material manufactured by applying hot-forging to S20, but other kinds of materials, forgings can be properly applied. The weight  8   w  is made of a material having larger specific gravity than that of the head body  7 . For instance, the weight  8   w  is made from tungsten, tungsten alloy.  
      An inner circumference  6   a  of the receiving portion  6  is tapered so as to allow a width A of an aperture portion  9  of the concaved receiving portion  6  to be gradually wider than a width B of a recess portion  10  which extends from the aperture portion  9  toward a center of the head  2  with respect to the aperture portion  9 . The recess portion  10  is formed so as to have a bottom. An outer circumference  8   a  of the weight  8   w  is tapered so as to allow a width C of a front portion  11  defined on an exterior of the weight  8   w  to be substantially equal to the width A of the aperture portion  9 , and be gradually wider than a width D of a rear portion  12  opposite to the front portion  11  toward the center of the head  2 . Accordingly, the widths A, B, C, D are expressed as follows: A=C; and A, C&gt;D&gt;B. Moreover, a depth E of the receiving portion  6  is defined so as to be slightly larger than a thickness F between the front portion  11  of the weight  8   w  and the rear portion  12  thereof (E&gt;F). A taper angle X of the inner circumference  6   a , and a taper angle Y of the outer circumference  8   a  are set at 3-15 degree, respectively, but preferably 5-10 degree. Both angles are substantially equal. The width A, B, C, D, the depth E and the thickness F are measured at the same cross sectional portion. The inner circumference  6   a  and the outer circumference  8   a  may not be entirely tapered, but it should be partially tapered. For instance, the inner and outer circumferences  6   a  and  8   a  may have straight portions as long as it is partially tapered.  
      Next, a method for manufacturing thereof will now be described. The head body  7  and the weight  8   w  are pre-manufactured, respectively. The head body  7  is set up on a non-illustrated pedestal so as to allow the receiving portion  6  to be turned upwardly. The weight  8   w  is inserted into the aperture portion  9  of the receiving portion  6  so as to drop it into the aperture portion  9  of the receiving portion  6 , and then pressed therein. When pressing, since the width C of the weight  8   w  is substantially equal to the width A of the aperture portion  9 , the front portion  11  is fitted into the aperture portion  9 , and the rear portion  12  is placed at the middle of the receiving portion  6 , the inner circumference  6   a  fits the outer circumference  11   a , whereby a clearance  14  having a thickness of less than or equal to 2 mm, preferably 1 mm is defined between the rear portion  12  and the recess portion  10 . Meanwhile, the widths A, B, C, D, the depth E and the thickness E respectively denote widths, depth and thickness of the corresponding portions.  
      In a case that a dimensional accuracy of the receiving portion  6  or the weight  8   w  is low, for instance, the width C of the front portion  11  of the weight  8   w  or the width D of the rear portion  12  thereof is smaller than its predetermined size, the weight  8   w  is inserted into the aperture portion  9  so as to drop the weight  8   w  thereinto, the front portion  11  fits in the back of the aperture portion  9 , the rear portion  12  is placed at the back of the inner circumference  6   a  locating at the middle thereof, and the inner circumference  6   a  fits the outer circumference  11   a . In this case, the clearance  14  slightly shorter than that of the above case is provided between the rear portion  12  and the recess portion  10 . By providing the clearance  14 , fitting the weight  8   w  into the receiving portion  6  is made possible even if the dimensional accuracy of the weight  8   w  is low.  
      When the head  2  manufactured thus way was plated, no soaking of a plating solution was observed in a plating process. Accordingly, it was assured that the inner circumference  6   a  and the outer circumference  8   a  were closely contact with each other. Moreover, a hitting test of 2,000 golf balls at a head speed of 43 m/s was carried out, but any problem such as one regarding strength of the golf club did not arise.  
      As described above, according to the first embodiment, the inner circumference  6   a  of the receiving portion  6  is tapered so as to allow the width A of the aperture portion  9  to be gradually wider than the width B of the recess portion  10 , the outer circumference  8   a  of the weight  8   w  is tapered so as to allow the width C of the front portion  11  to be substantially equal to the width A of the aperture portion  9  and be gradually wider than the width D of the rear portion  12 , while the depth E of the receiving portion  6  is defined so as to be slightly larger than the thickness F between the front portion  11  and the rear portion  12 . Accordingly, by fitting the weight  8   w  into the receiving portion  6  so as to drop the weight  8   w  into the receiving portion  6 , the receiving portion  6  and the weight  8   w  can be accurately fitted with each other without a gap at a comparatively low cost even if the dimensional accuracies of the receiving portion  6  and the weight  8   w  are lower than the predetermined ones.  
      Further, the width C of the front portion  11  is substantially equal to the width A of the aperture portion  9 , whereby the front portion  11  can be placed at the aperture portion  9 .  
      Still further, the taper angle X of the inner circumference  6   a  is substantially equal to the taper angle Y of the outer circumference  8   a , thereby allowing the inner circumference  6   a  to closely contact the outer circumference  8   a.    
      Next, a second embodiment of the present invention will now be described with reference to FIGS.  4  to  7 . The same reference numbers will denote the same structure portions, while detailed explanations thereof will be omitted. The head  2  having the hosel  3  and the sole  5  comprises: the head body  7  as one member concavely formed with the receiving portion  6  corresponding to the face  4 ; and a face member  8  as the other member of tabular fitted into the receiving portion  6 . The head body  7  is made of an iron-based material, while the face member  8  is made from, for instance, titanium, titanium alloy, and thus they are made from different metals.  
      The inner circumference  6   a  of the receiving portion  6  is tapered so as to allow the width A of the aperture portion  9  of the concaved receiving portion  6  to be gradually wider than the width B of the recess portion  10  which extends from the aperture portion  9  toward the center of the head  2  with respect to the aperture portion  9 . The recess portion  10  is formed so as to have a bottom. The outer circumference  8   a  of the face member  8  is tapered so as to allow the width C of the front portion  11  defined on an exterior of the face member  8  to be substantially equal to the width A of the aperture portion  9  and be gradually wider than the width D of the rear portion  12  opposite to the front portion  11  toward the center of the head  2 . Accordingly, the widths A, B, C, D are expressed as follows: A=C; and A, C&gt;D&gt;B. Moreover, the depth E of the receiving portion  6  is formed so as to be slightly larger than the thickness F between the front portion  11  of the face member  8  and the rear portion  12  thereof (E&gt;F). Meanwhile, the taper angle X of the inner circumference  6   a , the taper angle Y of the outer circumference  8   a  are set at 3-15 degree, respectively, but preferably 5-10 degree. Both angles are substantially equal.  
      Next, a method for manufacturing thereof will now be described. The head body  7  and the face member  8  are pre-manufactured, respectively. The head body  7  is set up on a pedestal  13  so as to allow the receiving portion  6  to be turned upwardly. The face member  8  is inserted into the aperture portion  9  of the receiving portion  6  drop the face member  8  thereinto, and then pressed therein. When pressing, since the width C of the front portion  11  of the face member  8  is substantially equal to the width A of the aperture portion  9 , the front portion  11  is fitted into the aperture portion  9 , and the rear portion  12  is placed at the middle of the receiving portion  6 , the inner circumference  6   a  fits the outer circumference  11   a , whereby the clearance  14  is defined between the rear portion  12  and the recess portion  10 .  
      In a case that a dimensional accuracy of the receiving portion  6  or the face member  8  is low, for instance, the width C of the front portion  11  of the face member  8  or the width D of the rear portion  12  thereof is smaller than its predetermined size, the face member  8  is inserted into the aperture portion  9  so as to drop the face member  8  thereinto, the front portion  11  fits in the back of the aperture portion  9 , the rear portion  12  is placed at the back of the inner circumference  6   a  locating at the middle thereof, and the inner circumference  6   a  fits the outer circumference  11   a . In this case, the clearance  14  slightly shorter than that of the above case is provided between the rear portion  12  and the recess portion  10 . By providing the clearance  14 , fitting the face member  8  into the receiving portion  6  is made possible even if the dimensional accuracy of the face member  8  is low.  
      Meanwhile, a copper-plating layer  4   a  is formed on a surface of the face  4 , while a corroded rough layer  4   b  is formed on the copper-plating layer  4   a . The copper-plating layer  4   a  is made from either copper cyanide or copper sulfate, and formed so as to have a thickness H of at least greater than or equal to about 20 μm. The corroded rough layer  4   b  is a product of corrosion produced by applying a later-described process of corrosion to the copper-plating layer  4   a , it forms a rough surface  4   c  having irregularity on a surface of the face  4 . The corroded rough layer  4   b  is purplish, different from the brown copper-plating layer  4   a.    
      Next, a method for manufacturing a pitching wedge employing the above-described structure will now be explained. First, in a first process, the face  4  is polished so as to allow the surface thereof to be flat.  
      As a second process, a masking sheet (not illustrated) is applied to the entire surface of the head  2  except the face  4 , so that the face  4  is exposed, while the portions of the head  2  except the face  4  are covered by a masking tape.  
      In this condition, as a third process, copper plating using copper cyanide or copper sulfate is applied to the head  2  by a well known electroplating technique, copper cyanide or copper sulfate is deposited on the exposed surface of the face  4 , thereby forming the copper-plating layer  4   a  having 30 μm of the thickness H thereon.  
      Next, as a fourth process, the surface of the copper-plating layer  4   a  formed on the face  4  is polished using a fabric-made buff so as to be flat and smooth, whereby the face  4  is mirror finished. The face  4  is cleaned by a liquid of trichloroethylene of 70-80° C. so that greases, other contaminations are removed therefrom, and then the face member  8 , which is heated by the trichloroethylene-cleaning, is cooled down with standing it to cool.  
      As a fifth process, the face  4  is soaked in a corrosive liquid of a room temperature, which is pre-produced by mixing potassium sulfide (K20), copper acetate ((CH3C00)Cu·H20) and potassium alum (AIK(S04)2·12H20), for about 5 seconds so as to cause the copper-plating layer  4   a  deposited on the surface of the face  4  to corrode. Accordingly, the corroded rough layer  4   b , which includes the rough surface  4   c  having irregularity, and changed its color to purple so as to have a different color from that of the copper plating layer  4   a , is formed on the surface of the copper plating layer  4   a.    
      Practically, in a case of the second embodiment, by soaking the face  4  for about 5 seconds, the copper-plating layer  4   a  deposited on the surface of the face  4  was corroded, so that the corroded rough layer  4   b  was formed, but the thickness H of the remained copper-plating layer  4   a  not corroded became at least greater than or equal to about 20 μm.  
      As a six process, the head  2  is washed by hot-water in order to remove the corrosive liquid or the like remaining on the surface of the corroded rough layer  4   b , it is dried out, and then the masking tape is removed therefrom. Accordingly, there is provided the head  2  that has the face  4  having the irregular rough surface  4   c  and changed its color to purple.  
      According to the above-described structure, by forming the corroded rough layer  4   b  on the surface of the face  4 , a golf ball (not illustrated) contacts the irregular rough surface  4   c  when hitting, thereby increasing a friction between the face  4  and the golf ball. Consequently, the head  2  can give more spin to the golf ball compared to by conventional ones.  
      Moreover, by allowing the copper-plating layer  4   a  to be corroded using the corrosive liquid, the rough surface  4   c  having more irregular asperity can be formed on the face  4 , thereby further increasing the friction between the face  4  and the golf ball.  
      As described, according to the second embodiment, the inner circumference  6   a  of the receiving portion  6  is tapered so as to allow the width A of the aperture portion  9  to be gradually wider than the width B of the recess portion  10 , while the outer circumference  8   a  of the face member  8  is tapered so as to allow the width C of the front portion  11  to be substantially equal to the width A of the aperture portion  9  and be wider than the width D of the rear portion  12 , while the depth E of the receiving portion  6  is slightly larger than the thickness F between the front portion  11  and the rear portion  12 . Accordingly, by fitting the face member  8  into the receiving portion  6  so as to drop the face member  8  thereinto, the receiving portion  6  and the face member  8  can be accurately fitted with each other without a gap at a comparatively low cost even if the dimensional accuracies of the receiving portion  6  and the face member  8  are lower than the predetermined ones. In a case that plating layers (not illustrated) are formed on the surface of the face member  8  and that of receiving portion  6 , respectively, the sizes thereof slightly differ from the predetermined ones, but they can be accurately fitted with each other by fitting the face member  8  into the receiving portion  6  so as to drop the face member  8  thereinto.  
      Further, the width C of the front portion  11  is substantially equal to the width A of the aperture portion  9 , whereby the front portion  11  can be placed at the aperture portion  9 .  
      Still further, the taper angle X of the inner circumference  6   a  is substantially equal to the taper angle Y of the outer circumference  8   a , thereby allowing the inner circumference  6   a  to closely contact the outer circumference  8   a.    
      Next, a third embodiment of the present invention will now be described with reference to FIGS.  8  to  9 . The same reference numbers will denote the same structure portions as those of the second embodiment, while detailed explanations thereof will be omitted. In the third embodiment, one end of the inner circumference  6   a  of the receiving portion  6  is integrally formed with a protrusion  21 , while an edge of the face member  8  is chamfered. When manufacturing, the face member  8  is fitted into the receiving portion  6  so as to drop the face member  8  thereinto, and then the head body  7 , in particular, the protrusion  21  or the portion around it is crushed so as to fill a chamfered portion  22  and form a crushed portion  23 , thereby firmly fixing the face member  8  to the head body  7 .  
      By crushing the protrusion  21 , the chamfered portion  22  is filled, and thus a separation of the face member  8  from the head body  7  can be prevented.  
      Next, a fourth embodiment of the present invention will now be described with reference to FIGS.  10  to  11 . The same reference numbers will denote the same structure portions as those of the second embodiment, while detailed explanations thereof will be omitted. In the fourth embodiment, the recess portion  10  of the concaved receiving portion  6  of the head body  7  is formed with a through-hole  31  opening toward the rearward of the head body  7 . Accordingly, the rear portion  12  of the face member  8  can be exposed on the rear side of the head  2  via the through-hole  31 .  
      By forming the recess portion  10  with the through-hole  31  so as to expose the rear portion  12  on the rear side of the head  2 , an elastic deformation of the face member  8  when hitting a golf ball can be enhanced.  
      Next, a fifth embodiment of the present invention will now be described with reference to FIGS.  12  to  13 . In the fifth embodiment, the receiving portion  6  is formed at a substantial center of the sole  5  of the head body  7 , while a sole member  41  is fitted into the receiving portion  6 . The inner circumference  6   a  of the receiving portion  6  is tapered so as to allow the width A of the aperture portion  9  thereof to be gradually wider than the width B of the recess portion  10 , while an outer circumference  41   a  of the sole member  41  is tapered so as to allow the width C of the front portion  11  of the sole member  41  to be substantially equal to the width A of the aperture portion  9  and be gradually wider than the width D of the recess portion  12 . The depth E of the receiving portion  6  is slightly larger than the thickness F between the front portion  11  of the sole member  41  and the rear portion  12  thereof.  
      For instance, in a case that the width C of the front portion  11  of the sole member  41  or the width D of the rear portion  12  thereof is smaller than its predetermined size, the sole member  41  is inserted into the aperture portion  9  so as to drop the sole member  41  thereinto, the front portion  11  fits in the back of the aperture portion  9 , the rear portion  12  is placed at the back of the inner circumference  6   a  locating at the middle thereof, and the inner circumference  6   a  fits the outer circumference  11   a . Accordingly, the sole member  41  can be accurately fitted into the receiving portion  6  without a gap at a comparatively low cost even if the dimensional accuracies thereof are low.  
      The present invention is not limited to the above embodiment, various embodiments and changes may be made thereonto without departing from the broad spirit and scope of the invention. The structure portions of the golf club head of the present invention are not limited to ones described in the above-described embodiments. The method for manufacturing the golf club of the present invention may be applied to, for instance, an attachment of a back member fitted into a rear side of the head.