Abstract:
According to an aspect of this invention, a golf club head includes: a head main body; and a weight material detachably mounted in a weight material mounting portion in the head main body, an external screw thread on the weight material meshing with an internal screw thread in the weight material mounting portion, wherein: the weight material comprises a head portion having the external screw thread and a rod portion which projects from the head portion; and the internal screw thread is provided on an entrance side and a cylindrical portion is provided on a deeper side for engagement with the rod portion in the weight material mounting portion.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a golf club head and more particularly to a golf club head which includes a weight material. 
         [0003]    2. Description of the Related Art 
         [0004]    A golf club has a head which is attached to a distal end portion of a shaft. A grip is attached to a proximal end of the shaft. 
         [0005]    In a general golf club head, a hosel hole is provided directly in the head, and a shaft is inserted into the hosel hole to be secured therein by an adhesive. 
         [0006]    A golf club head is used in which a weight material is detachably mounted in the golf club head by being screwed thereinto to adjust the weight or balance of the golf club head (for example, JP-A-2010-69106). 
         [0007]      FIG. 10  is a sectional view of a golf club head of JP-A-2010-69106. In this golf club head, an internally screw threaded hole  3  is provided in a sole portion of a head main body  2 , and a weight material (a deadweight member)  4  is detachably mounted in the internally screw threaded hole  3  by being screwed thereinto. 
         [0008]    When the weight material  4  is screwed into the internally screw threaded hole  3  in the way described above, the weight material  4  is placed at the entrance of the internally screw threaded hole  3  and a tool is brought into engagement with the weight material  4  to screw the weight material  4  into the internally screw threaded hole  3 . As this occurs, in placing the weight material  4  at the entrance of the internally screw threaded hole  3 , the weight material  4  needs to be placed thereat properly concentrically with much care before it is turned by the tool. Should the axial direction of the weight material  4  intersects obliquely the axial direction of the internally screw threaded hole  3 , even when the weight material  4  is turned, the weight material  4  is not screwed into the internally screw threaded hole  3 , or the weight material  4  is forced to be screwed into the internally screw threaded hole  3  with the weight material  4  kept inclined, resulting in fears that the screw threaded surface of the internally screw threaded hole  3  is damaged. 
         [0009]    Additionally, in the conventional example shown in  FIG. 10 , when the weight material  4  is placed at the entrance of the internally screw threaded hole  3  or is turned, the weight material  4  tends to come off easily from the internally screw threaded hole  3 . Due to these facts, with the conventional golf club head, it takes some labor hours to mount the weight material. 
       SUMMARY 
       [0010]    An object of the invention is to provide a golf club head which enables an easy mounting of a weight material in an internally screw threaded hole. 
         [0011]    According to the invention, there is provided a golf club head including: a head main body; and a weight material detachably mounted in a weight material mounting portion in the head main body, an external screw thread on the weight material meshing with an internal screw thread in the weight material mounting portion, wherein: the weight material comprises a head portion having the external screw thread and a rod portion which projects from the head portion; and the internal screw thread is provided on an entrance side and a cylindrical portion is provided on a deeper side for engagement with the rod portion in the weight material mounting portion. 
         [0012]    The rod portion may be rotatable relative to the head portion. 
         [0013]    A part having a different specific weight may be detachably attached to the weight material. 
         [0014]    The weight material may be mounted in a sole portion of the golf club head in an inclined direction. 
         [0015]    In the golf club head of the invention, in mounting the weight material in the weight material mounting portion, the rod portion of the weight material is brought into engagement with the cylindrical portion of the weight material mounting portion. By doing so, not only can the weight material be prevented from coming off from the weight material mounting portion, but also the weight material can be positioned concentrically with the weight material mounting portion, whereby the weight material can easily be screwed into the weight material mounting portion. 
         [0016]    When the rod portion is made rotatable relative to the head portion, it is possible to screw the weight material into the weight material mounting portion by turning only the head portion. 
         [0017]    The weight of the weight material can be adjusted by attaching the part having the different specific weight to the weight material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawing which is given byway of illustration only, and thus is not limitative of the present invention and wherein: 
           [0019]      FIG. 1  is a sectional view of a weight material mounting portion according to an embodiment of the invention; 
           [0020]      FIG. 2  is a perspective view of a weight material in  FIG. 1 ; 
           [0021]      FIG. 3  is a sectional view taken along the line in  FIG. 2 ; 
           [0022]      FIGS. 4A and 4B  are diagrams showing a state in which a weight material is being mounted into the weight material mounting portion shown in  FIG. 1 ; 
           [0023]      FIG. 5  is a perspective view showing another weight material; 
           [0024]      FIG. 6A  is a sectional view of a further weight material, and  FIG. 6B  is a sectional view taken along the line B-B in  FIG. 6A ; 
           [0025]      FIG. 7A  is a sectional view of a further weight material, and  FIG. 7B  is a perspective view of the weight material; 
           [0026]      FIG. 8  is a sectional view of another weight material; 
           [0027]      FIG. 9  is a sectional view of a weight material mounting portion of a golf club head according to another embodiment of the invention; 
           [0028]      FIG. 10  is a sectional view of a conventional golf club head; 
           [0029]      FIG. 11  is a side view of a golf club head according to a further embodiment of the invention; and 
           [0030]      FIG. 12  is a sectional view of a weight material mounting portion in the golf club head shown in  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    Hereinafter, embodiments of the invention will be described by reference to the drawings. 
         [0032]      FIGS. 1 to 4B  show a golf club head  5  according to a first embodiment. This golf club head  5  has a head main body  6 , weight material mounting portions  7  which are provided in a sole portion and a back portion of the head main body  6 , and a weight material  10  adapted to be detachably mounted in any of the weight material mounting portions  7  by being screwed thereinto. 
         [0033]    As shown in  FIGS. 4A and 4B , the weight material mounting portion  7  has an internally screw threaded portion  7   a  which is provided on an entrance side and a cylindrical portion  7   b  having no internal screw thread which is provided on a deep side thereof. In this embodiment, a circumferential edge portion of an entrance of the weight material mounting portion  7  is chamfered to thereby form a chamfered or tapered surface  7   c  thereat. A bore diameter of the tube portion  7   b  is smaller than a bore diameter of the internally screw threaded portion  7   a,  and a step portion  7   d  is formed at a boundary portion between the internally screw threaded portion  7   a  and the cylindrical portion  7   b.  In this embodiment, the cylindrical portion  7   b  has a circular cylindrical shape. A corner portion at a deepest portion of the cylindrical portion  7   b  is formed into a tapered surface  7   e.    
         [0034]    As shown in  FIG. 2 , the weight member  10  has a head portion  11  on an outer circumferential surface of which an external screw thread is provided, and a rod portion  12  which is secured to the head portion  11 . Tool engagement holes  11   a,    11   b  are provided in a top end surface of the head portion  11 . 
         [0035]    As shown in  FIG. 1 , an opposite surface of the head portion  11  to the top end surface is formed into a recess portion  11   c,  and the rod portion  12  is inserted into this recess portion  11   c.  A locking recess portion  11   d  is provided in a deep bottom surface of the recess portion  11   c,  and an entrance side of this locking recess portion  11   d  is smaller in diameter than a deep side thereof. 
         [0036]    The rod portion  12  has a main body portion  12   a  which projects from the head portion  11 , a small diameter portion  12   b  that is smaller in diameter than the main body portion  12   a  and which is inserted into the recess portion  11   c,  and a locking projecting portion  12   c  which projects from a distal end face of the small diameter portion  12   b.  This locking projecting portion  12   c  is smaller in diameter at a proximal end than at a distal end thereof and has the same shape and size as those of the locking recess portion  11   d.  This locking projecting portion  12   c  is fitted in the locking recess portion  11   d  through cooling fit, shrink-fit or forced fit, whereby the head portion  11  and the rod portion  12  are integrated into a single body. 
         [0037]    The rod portion  12  is concentric with the head portion  11 . In this embodiment, the rod portion  12  may be rotatable or prohibited to rotate relative to the head portion  11 . 
         [0038]    In mounting the weight material  10  in the weight material mounting portion  7 , as shown in  FIG. 4A , the weight material  10  is caused to approach the weight material mounting portion  7 . Then, as shown in  FIG. 4B , the rod portion  12  of the weight material  10  is inserted into the cylindrical portion  7   b  of the weight material mounting portion  7 , whereafter a tool is brought into engagement with the tool engagement holes  11   a,    11   b,  and the weight material  10  is turned by the tool. 
         [0039]    The rod portion  12  is provided on the weight material  10 , and the rod portion  12  is brought into engagement with the cylindrical portion  7   b  only by inserting the weight material  10  into the weight material mounting portion  7  as shown in  FIG. 4B , whereby the weight material  10  is placed concentric with the weight material mounting portion  7  accurately. Due to this, when the weight material  10  is turned from the state shown in  FIG. 4B , the external screw thread on the weight material  10  meshes smoothly with the internal screw thread in the inner circumferential surface of the internally screw threaded portion  7   a  of the weight material mounting portion  7 . When the weight material  10  is turned to be screwed into the weight material mounting portion  7  sufficiently, a lower end face of the head portion  11  is pressed against the step portion  7   d  strongly, whereby the weight material  10  is mounted firmly in the weight material mounting portion  7 . 
         [0040]    Additionally, in this embodiment, as shown in  FIG. 4B , the rod portion  12  is in engagement with the cylindrical portion  7   b  in such a state that the weight material  10  is inserted in the weight material mounting portion  7 , and therefore, it becomes difficult that the weight material  10  comes off from the weight material mounting portion  7  while the mounting work is being performed. 
         [0041]    In this way, according to the embodiment, the weight material  10  can be mounted in the weight material mounting portion  7  extremely easily. 
         [0042]    In the embodiment, while the rod portion  12  has the cylindrical shape, as in a weight material  10 A shown in  FIG. 5 , a rod portion  12 A may have a prism-like shape. As this occurs, the rod portion  12 A is left rotatable relative to a head portion  11 . The other configurations of the weight material  10 A shown in  FIG. 5  are the same as those of the weight material  10 , and like reference numerals denote like portions. 
         [0043]    In this invention, as in a weight material  10 B shown in  FIGS. 6A and 6B , a part  15  may be detachably attached to a rod portion  12  by being screwed thereinto. As this occurs, the weight of the weight material  10 B can be changed by detaching the part  15  or replacing the part  15  with another part having a different weight. The other configurations of the weight material  10 B are the same as those of the weight material  10 , and the other reference numerals in  FIGS. 6A and 6B  are denoted like portions to those of the weight material  10 . 
         [0044]    In a weight material  10 C shown in  FIGS. 7A and 7B , a through hole  11   e  is provided in a head portion  11 C so as to penetrate an axial portion thereof. A small diameter portion  12   b  of a rod portion  12 C is rotatably inserted into the through hole  11   e.  A stopper plate  17  is attached to a distal end face of the small diameter portion  12   b.  A locking projection  17   a  is provided on this stopper plate  17 , and this locking projection  17   a  is larger in diameter at a distal end than at a proximal end. This locking projection  17   a  is fitted in a locking recess portion  12   g  having the same configuration which is provided in the distal end face of the small diameter portion  12   b.  The stopper plate  17  is a circular disk which is larger in diameter than the through hole  11   e,  and the rod portion  12   c  cannot be removed from the head portion  11 C. 
         [0045]    A main body portion  12   a  of the rod portion  12 C is larger in diameter than the small diameter portion  12   b.  The small diameter portion  12   b  and the through hole  11   e  have a circular cross section which is normal to the direction of axes thereof, and the head portion  11 C is rotatable relative to the rod portion  12 C. The tool can be brought into engagement with tool engagement holes  11   f  in a top end face of the head portion  11 C to turn the head portion  11 C. 
         [0046]    In a weight material  10 D shown in  FIG. 8 , a rod portion  12 D is fastened to a head portion  11 D by a bolt  18  so that the head portion  11 D and the rod portion  12 D are integrated into a single body. The other configurations thereof are the same as those of the weight material  100 , and like reference numerals denote like portions. 
         [0047]    In the embodiments described above, while the weight material mounting portion  7  is not a through hole, as in a weight material mounting portion  7 ′ in a head main body  6 ′ shown in  FIG. 9 , the weight material mounting portion  7 ′ may be a hollow cylinder having a through hole which penetrates therethrough. The other configurations shown in  FIG. 9  are the same as those shown in  FIG. 1 , and like reference numerals denote like portions. 
         [0048]    In this invention, the weight material may be mounted in the sole portion in an inclined fashion.  FIG. 11  is a side view of a golf club head as seen from a heel side which shows an example of an inclined mounting of a weight material into a sole portion thereof, and  FIG. 12  is a vertical sectional view of a weight material mounting portion in the golf club head  5 ′ taken along a toe-to-heel direction of the head. As shown in the figures, a weight material mounting portion  7  is provided in a sole portion  5   a  of the golf club head  5 ′ in such a manner that an axial direction thereof intersects a horizontal plane which constitutes a surface of the sole portion  5   a  obliquely at an angle of θ as seen in the toe-to-heel direction of the head. This angle θ is in the range of 10 to 60°, preferably in the range of 20 to 50° and more preferably in the range of 30 to 45°. As shown in  FIGS. 11 ,  12 , the weight material mounting portion  7  is inclined so that a deep side thereof moves further forwards towards a toe side of the golf club head  5 ′ as it extends thereinto. 
         [0049]    When a weight material  10  is mounted in the sole portion  5   a  in the inclined fashion in the way described above, compared with when the weight member  10  is mounted in the golf club head  5 ′ normal to the surface of the sole portion  5   a,  it becomes difficult that the weight material  10  is loosened even when vibration generated at the time of impact is applied thereto. 
         [0050]    When the construction of ribs within the golf club head or an inner construction of the sole thereof is changed to make it difficult for the weight material  10  to be loosened, it happens from time to time that the natural frequency of the golf club head is changed to thereby change the striking sound or that the amplitude of vibration generated when the golf club head hits a golf ball becomes small due to the ribs. However, when the weight material mounting portion and the weight material are inclined, the occurrence of these changes in striking sound and vibration amplitude are prevented. When the angle θ is larger than 60°, the working effect described above becomes poor, while when the angle θ is smaller than 10°, the construction of the weight material mounting portion becomes complex, and the weight thereof is increased, whereby the extent of weight adjustment by the weight material is reduced.