Patent Publication Number: US-2021178242-A1

Title: Variable golf putter

Description:
TECHNICAL FIELD 
     The present disclosure relates to a variable golf putter, and more particularly to a variable golf putter capable of replacing and using a hitting surface of the putter and of providing various hitting sensations, thereby efficiently performing putting practice to accurately putt a golf ball on a putting green into a hole cup. 
     BACKGROUND ART 
     In general, a putter is a tool used when directly hitting a ball on a green toward a hole cup using an iron club for putting, and putting means an action of hitting a ball using a putter. 
     In order to successfully perform putting, a putting direction and sense of distance are important. However, the most basic requirement is a correct putting posture. To this end, a great number of practice putts may need to be performed for a long time to learn such a sensation. 
     Here, the correct putting posture means that both hands holding a grip perform a pendulum motion about the head of a golfer at the time of swing and the head of a putter impacts a ball at the lowest point of the pendulum motion. The ball hit at the posture described above will travel to a desired position. 
     If the wrists are bent or the body shakes at the time of swing, the pendulum motion is not accurately performed. As a result, the ball is impacted at an inappropriate position, whereby the ball is not sent to a desired position. 
     In order to solve this problem, putting practice may be performed using a putter for practice. 
     As a prior art document, a putter for golf practice is disclosed in Korean Registered Utility Model No. 20-0350462 (published on May 13, 2004). 
     As shown in  FIG. 1 , a conventional putter  1  for golf practice is configured such that a triangular or semicircular hitting protrusion  2 A configured to accurately hit a golf ball  2  is formed at the center of the front of a putter head  2 . The putter  1  for golf practice has an advantage in that it is possible to perform practice of accurately hitting the golf ball  3  using the semicircular hitting protrusion  2 A. 
     In the putter  1  described above, however, the putter head  2  and the hitting protrusion  2 A are integrally formed, whereby it is not possible to apply hitting protrusions  2 A having various structures. 
     As another prior art document, a putting practice member for golf putters is disclosed in Korean Registered Utility Model No. 20-0395835 (published on Sep. 14, 2005). As shown in  FIG. 2 , fixing plates  1 ′ and  1 ″ are formed at opposite sides of a putting member  1  having a hitting portion  1 A having the largest width formed at the middle portion thereof and a center line  101  marked on the upper surface thereof, the putting member  1  is fixed to a putter head  2  using rubber bands  3  in the state in which the fixing plates  1 ′ and  1 ″ are in contact with the putter head  2 . The putting practice member having the structure described above is configured to replace the putting member  1 . Since the putting member  1  is coupled to the putter head using the rubber bands  3 , however, it is not possible to maintain strong force of coupling therebetween. 
     Also, in the above prior art documents, the putter head is made of a single material and is formed in a single shape, whereby it is not possible to learn various hitting sensations. 
     DISCLOSURE 
     Technical Problem 
     It is an object of the present disclosure to provide a variable golf putter capable of using various hitting surfaces and providing various hitting sensations. 
     The present disclosure is not limited to what has been described above, and other aspects not mentioned herein will be apparent from the following description to one of ordinary skill in the art to which the present disclosure pertains. 
     Technical Solution 
     In accordance with the present disclosure, the above object can be accomplished by the provision of a variable golf putter including a putter head coupled to the lower end of a shaft, the putter head having a head hitting surface, and a hitting member selectively coupled to the putter head, wherein a through hole, through which a fastening bolt extends upwards from the bottom surface thereof, is formed in the putter head so as to be stepped, an incision portion configured to open a portion of the upper surface of the putter head in a hitting direction is formed in the head hitting surface corresponding to the through hole, the hitting member is formed in a golf ball shape and has a hitting surface formed on the outer circumferential surface thereof, a seating surface and a supporting surface supported by an edge of the upper surface so as to be seated on the upper surface are formed at the bottom surface of the hitting member so as to be stepped, a screw fastening recess, to which the fastening bolt is coupled by fastening, is formed in the seating surface, the hitting member is replaceably coupled to the putter head via the fastening bolt in the state of being seated on the surface such that a portion of the hitting surface protrudes through the incision portion more than the head hitting surface, the hitting surface of the hitting member is constituted by a spherical hitting surface having the same curvature as a golf ball or a planar hitting surface, and, in the case in which the hitting surface is constituted by a planar hitting surface, a plurality of hitting members is provided by area of the planar hitting surface and is selectively coupled to the putter head. 
     In accordance with the present disclosure, the above object can be accomplished by the provision of a variable golf putter including a putter head coupled to the lower end of a shaft, the putter head having a head hitting surface, and a hitting member selectively coupled to the putter head, wherein a through hole, through which a fastening bolt extends upwards from the bottom surface thereof, is formed in the putter head so as to be stepped, an incision portion configured to open a portion of the upper surface of the putter head in a hitting direction is formed in the head hitting surface corresponding to the through hole, a triangular to octagonal coupling protrusion protrudes upwards from the upper surface in which the through hole is formed, the hitting member is formed in a golf ball shape or a polygonal shape, hitting surfaces having different shapes and different sizes are formed on the outer surface of the hitting member, a seating surface, which is seated on the upper surface, is formed at the bottom surface of the hitting member, a triangular to octagonal coupling recess is formed in the seating surface such that the coupling protrusion is inserted into and coupled to the coupling recess when the seating surface is seated on the upper surface, and has coupling surfaces having identical directions to the hitting surfaces, a screw fastening recess, to which the fastening bolt is coupled by fastening, is formed in the coupling recess, the coupling protrusion is coupled to the coupling recess in the state in which an orientation of the hitting member is set such that a hitting surface selected from among the hitting surfaces is exposed through the incision portion, the fastening bolt is coupled to the screw fastening recess of the coupling recess through the through hole by fastening, the hitting surface of the hitting member is constituted by a spherical hitting surface having identical curvature to a golf ball or a planar hitting surface, and, in the case in which the hitting surface is constituted by a planar hitting surface, a plurality of hitting members is provided by area of the planar hitting surface and is selectively coupled to the putter head. 
     A hitting material made of a material different from the material of the hitting member may be provided integrally at the spherical hitting surface or the planar hitting surface, and a hitting material recess formed in the spherical hitting surface or the planar hitting surface may be filled with the hitting material, or the hitting material may be integrally formed with the hitting member through insert injection molding. 
     The lower end of the shaft may be formed in a polygonal shape, polygonal coupling portions, to each of which the lower end of the shaft is coupled, may be formed at opposite sides of the putter head such that one of the polygonal coupling portions is selected and used by a left-handed person or a right-handed person, and the lower end of the shaft and the coupling portion may be coupled to each other via a bolt fastened from the bottom surface of the putter head in the state in which the lower end of the shaft is fitted in the coupling portion such that the coupling angle therebetween is adjusted. 
     A thickness adjustment recess may be formed around the coupling recess of the hitting member, and the thickness adjustment recess may be formed so as to have different widths such that the hitting surfaces have different thicknesses based on the coupling surfaces, whereby different hitting sensations and hitting sounds are generated. 
     In accordance with the present disclosure, the above object can be accomplished by the provision of a variable golf putter including a putter head having a coupling bar, one end of which is coupled to the lower end of a shaft, the coupling bar extending in a horizontal direction, and a hitting member having a hitting surface configured to hit a golf ball, the hitting surface being formed on one side thereof, and a spherical or planar practice hitting surface formed on the other side thereof, the hitting member being coupled to the coupling bar of the putter head, wherein the hitting member is formed as a single body or is divided into two or five parts having different sizes and shapes such that the hitting surface and the practice hitting surface are selected, the hitting member being coupled to the coupling bar, the lower end of the shaft is formed in a polygonal shape, a polygonal coupling portion, to which the lower end of the shaft is coupled, is formed at the putter head, and the lower end of the shaft and the coupling portion are coupled to each other via a bolt fastened from the bottom surface of the putter head in the state in which the lower end of the shaft is fitted in the coupling portion such that the coupling angle therebetween is adjusted. 
     A hitting material made of a material different from the material of the hitting member may be provided integrally at the hitting surface and the practice hitting surface, and hitting material recesses formed in the hitting surface and the practice hitting surface may be filled with the hitting material, or the hitting material may be integrally formed with the hitting member through insert injection molding. 
     In the case in which the hitting member is divided, the divided hitting members may be made of different materials. 
     In the case in which the practice hitting surface is formed in a spherical shape, a spherical hitting portion having curvature smaller than curvature of the outer circumferential surface of the hitting member may be formed at the practice hitting surface, and a spherical hitting surface may be formed at the spherical hitting portion. 
     In accordance with the present disclosure, the above object can be accomplished by the provision of a variable golf putter including a putter head coupled to the lower end of a shaft, wherein the putter head includes a first hitting member which is formed in a spherical shape having a golf ball shape and to which the lower end of the shaft is coupled, a second hitting member which is formed in a spherical shape having a golf ball shape and which is coupled to a side surface of the first hitting member in a horizontal direction so as to be located on a straight line together with the first hitting member, a third hitting member which is formed in a spherical shape having a golf ball shape and which is coupled to a side surface of the second hitting member in the horizontal direction so as to be located on a straight line together with the first hitting member and the second hitting member, and a coupling rod having one end to which a nut is fastened after the coupling rod extends through the first hitting member, the second hitting member, and the third hitting member and the other end to which the shaft is fastened, the coupling rod being configured to integrate the first hitting member, the second hitting member, and the third hitting member, a spherical hitting surface having identical curvature to a golf ball and planar hitting surfaces are formed at each of the first hitting member, the second hitting member, and the third hitting member, the planar hitting surfaces being formed so as to have different sizes, the first hitting member, the second hitting member, and the third hitting member are made of different materials, a hitting material made of a material different from materials of the first hitting member, the second hitting member, and the third hitting member is provided integrally at the spherical hitting surface and the planar hitting surfaces, and hitting material recesses formed in the spherical hitting surface and the planar hitting surfaces are filled with the hitting material, or the hitting material is integrally formed with the hitting member through insert injection molding. 
     A position changing means configured to change positions of the second hitting member and the third hitting member, to select the spherical hitting surface and the planar hitting surfaces, and to change the hitting surfaces depending on whether a user is a right-handed person or a left-handed person may be provided at each of the first hitting member, the third hitting member, and opposite surfaces of the second hitting member that face the first hitting member and the third hitting member, and the position changing means may include a polygonal connection and coupling member having a predetermined length and a polygonal positioning recess formed in a corresponding one of opposite surfaces of the first hitting member, the second hitting member, and the third hitting member such that the connection and coupling member is coupled to the positioning recess by insertion. 
     In accordance with the present disclosure, the above object can be accomplished by the provision of a variable golf putter including a hitting member having one end coupled to the lower end of a shaft, a hitting surface configured to hit a golf ball being formed on one side of the hitting member, a spherical or planar practice hitting surface being formed on the other side of the hitting member, wherein the lower end of the shaft is formed in a polygonal shape, a polygonal coupling portion, to which the lower end of the shaft is coupled, is formed at the hitting member, and the lower end of the shaft and the coupling portion are coupled to each other via a bolt fastened from the bottom surface of the hitting member in the state in which the lower end of the shaft is fitted in the coupling portion such that the coupling angle therebetween is adjusted. 
     In accordance with the present disclosure, the above object can be accomplished by the provision of a variable golf putter including a putter head having a shaft coupling hole, to which the lower end of a shaft is coupled, and a head hitting surface, and a hitting member selectively coupled to the putter head, wherein a through hole, through which a fastening bolt extends upwards from the bottom surface thereof, is formed in the putter head so as to be stepped, an incision portion configured to open a portion of the upper surface of the putter head in a hitting direction is formed in the head hitting surface corresponding to the through hole, a coupling portion is formed around the through hole, a hitting surface is formed at one or each of outer surfaces of the hitting member, a coupling recess, to which the coupling portion is coupled by insertion, is formed in the bottom surface of the hitting member so as to be open downwards, a screw fastening recess is formed in the bottom surface of the coupling recess, the fastening bolt is fastened to the screw fastening recess through the through hole in the state in which the coupling portion is inserted into and coupled to the coupling recess such that the hitting surface protrudes through the incision portion more than the head hitting surface or coincides with the head hitting surface, whereby the hitting member is replaceably coupled to the putter head, and a hitting sound generation recess configured to generate a hitting sound when a golf ball is hit by all the hitting surface or a region of the hitting surface corresponding to a positive hitting point is formed in the hitting member. 
     The hitting sound generation recess may be formed in a region corresponding to the hitting surface or a region of the hitting surface corresponding to the positive hitting point so as to be open toward the bottom, the side, or the top of the hitting member or toward the coupling recess. 
     The hitting sound generation recess may be filled with a metal material or a synthetic resin material different from a material of the hitting member, the metal material or the synthetic resin material may be coupled to the hitting sound generation recess by insertion, or the metal material or the synthetic resin material may be integrally formed with the hitting member through insert injection molding. 
     The hitting member may be formed in the shape of a sphere, a hemisphere, or a combination of a polygon and a sphere, and a mark configured to indicate the hitting direction may be formed on the outer circumferential surface of the hitting member in the form of a plurality of recesses or a line. 
     A decorative member for decoration may be provided at the upper surface of the hitting member, and a portion of the decorative member may be coupled to the hitting member by insertion, or a fastening portion provided at the decorative member may be coupled to a screw hole formed in the upper surface of the hitting member by fastening. 
     Shaft coupling holes of the putter head may be formed in opposite sides of the putter head such that a right-handed person or a left-handed person selects one of the shaft coupling holes and couples the shaft to the selected shaft coupling hole. 
     In the case in which the hitting member is formed in the shape of a sphere, a hemisphere, or a combination of a polygon and a sphere, the hitting surface is formed at the outer circumference of the hitting member, and the distance between the center of the hitting member and a hitting position is preset, a hemispherical auxiliary member may be formed at the hitting surface so as to protrude and an auxiliary hitting surface may be formed at the hemispherical auxiliary member such that the area of the hitting surface is increased or decreased. 
     Advantageous Effects 
     According to the present disclosure, the hitting member has various hitting surfaces, whereby it is possible to putt and to perform putting practice in various manners. In addition, a hitting material made of a material different from the material of the hitting member is formed integrally with the hitting member, whereby it is possible to provide various hitting sensations and thus to efficiently perform putting practice. 
     In addition, a hitting sound generation recess is formed in the hitting member such that a bright hitting sound is generated when a golf ball is hit at a positive hitting point of the hitting surface, whereby it is possible to easily recognize that correct hitting has been performed. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIGS. 1 and 2  are views showing a conventional golf putter for practice. 
         FIG. 3  is an exploded perspective view showing a variable golf putter according to a first embodiment of the present disclosure. 
         FIGS. 4, 5, and 6  are perspective views showing other embodiments of a hitting member shown in  FIG. 3 . 
         FIG. 7  is a sectional view showing a coupling state of the golf putter for practice shown in  FIG. 3 . 
         FIG. 8  is a plan view showing a use state of the golf putter for practice shown in  FIG. 3 . 
         FIGS. 9, 10, 11, and 12  are views showing a variable golf putter according to a second embodiment of the present disclosure. 
         FIG. 13  is a schematic plan view showing a use state of the variable golf putter shown in  FIGS. 7 to 10 . 
         FIG. 14  is a perspective view showing a variable golf putter according to a third embodiment of the present disclosure. 
         FIG. 15  is an exploded perspective view showing a variable golf putter according to a fourth embodiment of the present disclosure. 
         FIG. 16  is a sectional view showing a coupling state of the variable golf putter shown in  FIG. 15 . 
         FIG. 17  is an exploded perspective view showing another embodiment of the variable golf putter shown in  FIG. 15 . 
         FIGS. 18, 19, and 20  are views showing other embodiments of a hitting member shown in  FIG. 17 . 
         FIG. 21  is an exploded perspective view showing a variable golf putter according to a fifth embodiment of the present disclosure. 
         FIG. 22  is a sectional view showing a coupling state of the variable golf putter shown in  FIG. 21 . 
         FIGS. 23 and 24  are plan views showing a use state of the variable golf putter shown in  FIG. 21 . 
         FIG. 25  is an exploded perspective view showing a variable golf putter according to a sixth embodiment of the present disclosure. 
         FIG. 26  is a perspective view showing a coupling state of the variable golf putter shown in  FIG. 25 . 
         FIG. 27  is a sectional view taken along line A-A of  FIG. 26 . 
         FIG. 28  is a bottom view showing a hitting member shown in  FIG. 26 . 
     
    
    
       
     
       
         
           
               
             
               
                   
               
               
                 * Description of reference symbols * 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 10: Shaft 
                 20, 200: Putter heads 
               
               
                 21: Coupling portion 
                 22: Through hole 
               
               
                 23: Upper surface 
                 23A: Edge 
               
               
                 24: Hitting surface of putter head 
                 25: Seating recess 
               
               
                 26: Incision portion 
                 27: Coupling protrusion 
               
               
                 30: Hitting member 
                 31: Hitting material recess 
               
               
                 32: Seating surface 
                 32A: Supporting surface 
               
               
                 32B: Screw fastening recess 
                 32C: Coupling recess 
               
               
                 32C-1: Coupling surface 
                 33: Coupling portion 
               
               
                 34, 340: Hitting surfaces 
                 34-1: Practice hitting surface 
               
               
                 34A, 34-2, 320: Spherical hitting 
                 34B, 340: Planar hitting surfaces 
               
               
                 surfaces 
               
               
                 35: Insertion recess 
               
               
                 37: Thickness adjustment recess 
                 39: Hitting material 
               
               
                 40: Fastening bolt 
                 210: Coupling bar 
               
               
                 300A: First hitting member 
                 300B: Second hitting member 
               
               
                 300C: Third hitting member 
                 400: Coupling rod 
               
               
                 500: Position changing means 
                 510, 510A, 510B: Connection and 
               
               
                   
                 coupling members 
               
               
                 520: Positioning recess 
               
               
                   
               
            
           
         
       
     
     BEST MODE 
     The present disclosure provides a variable golf putter including a putter head coupled to the lower end of a shaft, the putter head having a head hitting surface, and a hitting member selectively coupled to the putter head, wherein a through hole, through which a fastening bolt extends upwards from the bottom surface thereof, is formed in the putter head so as to be stepped, an incision portion configured to open a portion of the upper surface of the putter head in a hitting direction is formed in the head hitting surface corresponding to the through hole, the hitting member is formed in a golf ball shape and has a hitting surface formed on the outer circumferential surface thereof, a seating surface and a supporting surface supported by an edge of the upper surface so as to be seated on the upper surface are formed at the bottom surface of the hitting member so as to be stepped, a screw fastening recess, to which the fastening bolt is coupled by fastening, is formed in the seating surface, the hitting member is replaceably coupled to the putter head via the fastening bolt in the state of being seated on the surface such that a portion of the hitting surface protrudes through the incision portion more than the head hitting surface, the hitting surface of the hitting member is constituted by a spherical hitting surface having the same curvature as a golf ball or a planar hitting surface, and, in the case in which the hitting surface is constituted by a planar hitting surface, a plurality of hitting members is provided by area of the planar hitting surface and is selectively coupled to the putter head. Consequently, a user may select the hitting surface and may then couple the hitting member to the putter head, whereby various hitting sensations may be provided to the user. 
     MODE FOR INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. In the following description of the present disclosure, however, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present disclosure. 
     Among the accompanying drawings,  FIG. 3  is an exploded perspective view showing a variable golf putter according to a first embodiment of the present disclosure,  FIGS. 4, 5, and 6  are perspective views showing other embodiments of a hitting member shown in  FIG. 3 ,  FIG. 7  is a sectional view showing a coupling state of the golf putter for practice shown in  FIG. 3 , and  FIG. 8  is a plan view showing a use state of the golf putter for practice shown in  FIG. 3 . 
     As shown in  FIGS. 3 to 8 , the variable golf putter according to the first embodiment of the present disclosure includes a putter head  20  and a hitting member  30  selectively coupled to the putter head  20 . 
     The putter head  20  is coupled to the lower end  12  of a shaft  10 , and has a head hitting surface  24  formed in a hitting direction. 
     A through hole  22 , through which a fastening bolt  40  extends upwards from the bottom surface thereof, is formed in the putter head  20  so as to be stepped, and an incision portion  26  configured to open a portion of the upper surface  23  of the putter head  20  in the hitting direction is formed in the central region of the head hitting surface  24  corresponding to the through hole  22 . 
     The hitting member  30  is formed in a spherical shape, such as a golf ball shape, and has a hitting surface  34  formed on the outer circumferential surface thereof. A seating surface  32  and a supporting surface  32 A supported by the edge of the upper surface  23  of the putter head  20  so as to be seated on the upper surface  23  are formed at the bottom surface of the hitting member  30  so as to be stepped. A screw fastening recess  32 B, to which the fastening bolt  40  is coupled by fastening, is formed in the seating surface  32 . 
     The hitting member  30  is replaceably coupled to the putter head  20  via the fastening bolt  40  in the state of being seated on the surface  23  such that a portion of the hitting surface  34  of the hitting member  30  protrudes through the incision portion  26  more than the head hitting surface  23 . 
     The hitting surface  34  of the hitting member  30  is constituted by a spherical hitting surface  34 A having the same curvature as a golf ball or a planar hitting surface  34 B. In the case in which the hitting surface of the hitting member is constituted by a planar hitting surface  34 B, a plurality of hitting members  30  is provided by area of the planar hitting surface  34 B, and is selectively coupled to the putter head  20 . A hitting material  39  made of a material different from the material of the hitting member  30  is provided integrally at the spherical hitting surface  34 A or the planar hitting surface  34 B. 
     This will be described in more detail. 
     The through hole  22 , through which the fastening bolt  40  extends upwards from the bottom surface thereof, is formed in the putter head  20  so as to be stepped. The incision portion  26  configured to open a portion of the upper surface  23  of the putter head  20  in the hitting direction is formed in the central region of the head hitting surface  24  corresponding to the through hole  22 , i.e. equivalent to the region in which the through hole  22  is formed, as shown in  FIG. 3 . The incision portion  26  is configured to expose a portion of the hitting surface  34  forwards (in the hitting direction) when the hitting member  30  is coupled to the upper surface  23  of the putter head  20 . 
     The reason that the through hole  22  is formed so as to be stepped is that it may be necessary to prevent a head portion of the fastening bolt  40  from protruding outwards from the bottom surface of the putter head  20  when the fastening bolt  40  is coupled to the hitting member  30  through the through hole  22 . Preferably, the through hole  22  and the incision portion  26  are formed in the middle (the central region) of the putter head  20 . 
     The hitting member  30  is configured to be selectively coupled to or separated from the putter head  20 . The hitting member  30  is formed so as to have the same shape as a golf ball and to have a size equal or similar to the size of the golf ball, as shown in  FIG. 3 . The spherical or planar hitting surface  34  is formed on the outer circumferential surface of the hitting member  30 . The seating surface  32 , on which the upper surface  23  of the putter head  20  is seated, is formed on the bottom surface of the hitting member  30 , and the supporting surface  32 A, which is supported by the edge  23 A of the upper surface  23  when the seating surface  32  is seated on the upper surface  23 , is formed at one side of the seating surface  32  so as to be stepped. This structure is configured to stably absorb impact generated when hitting a golf ball using the hitting surface  34  by the provision of the supporting surface  32 A. In addition, the screw fastening recess  32 B, to which the fastening bolt  40  is coupled by fastening, is formed in the seating surface  32 , and has a female screw thread formed therein. 
     The hitting member  30  configured as described above is replaceably coupled to the putter head  20  via the fastening bolt  40  in the state of being seated on the surface  23  such that a portion of the hitting surface  34  of the hitting member  30  protrudes through the incision portion  26  more than the head hitting surface  23 . In addition, the head portion of the fastening bolt  40  is seated in the stepped through hole  33 , and therefore the head portion is prevented from protruding outwards from the bottom surface of the putter head  20  when the fastening bolt  40  is coupled to the screw fastening recess  32 B from the bottom surface of the putter head  20  through the through hole  22 . 
     The hitting surface  34  of the hitting member  30  is constituted by a spherical hitting surface  34 A having the same curvature as a golf ball or a planar hitting surface  34 B. In the case in which the hitting surface of the hitting member is constituted by a planar hitting surface  34 B, a plurality of hitting members  30  is preferably provided by area of the planar hitting surface  34 B. That is, in the case in which a plurality of hitting members  30  having different sizes of planar hitting surfaces  34 B is provided, a user may select a hitting member  30  having a desired size of a planar hitting surface  34 B, may couple the selected hitting member to the putter head  20 , and may use the putter head. 
     A hitting material  39  made of a material different from the material of the hitting member  30  is provided integrally at the spherical hitting surface  34 A or the planar hitting surface  34 B of the hitting member  30 . That is, as shown in  FIGS. 5, 6, and 7 , a plurality of hitting material recesses each having a predetermined depth is formed in the spherical hitting surface  34 A or the planar hitting surface  34 B, and the hitting material recesses  31  are filled with a hitting material  39  made of a material different from the material of the hitting member  30  so as to be integrated, or the hitting material is integrally formed with the hitting member  30  through insert injection molding. For example, in the case in which the hitting member  30  is made of iron, the hitting material recesses  31  are filled with a material other than iron, such as copper or aluminum, or integration between the hitting member and the hitting material is achieved through insert injection molding. 
     As described above, the hitting material recesses  31  are formed in the spherical hitting surface  34 A or the planar hitting surface  34 B, and a hitting material  39  made of a material different from the material of the hitting member  30  is provided integrally in the hitting material recesses  31 , whereby it is possible to provide various hitting sensations and hitting sounds to a user who putts. 
     In this embodiment, the hitting material recesses  31  are filled with the hitting material  39 , or the hitting material is integrally formed with the hitting member  30  through insert injection molding. However, the present disclosure is not limited thereto. As shown in  FIG. 18 , protrusions  31 - 1  may be formed on the bottoms of the hitting material recesses  31 , and gaps between the protrusions  31 - 1 , i.e. the hitting material recesses  31 , may be filled with the hitting material  39  so as to be integrated, or the hitting material may be integrally formed with the hitting member through insert injection molding. 
     Meanwhile, the variable golf putter according to this embodiment has a structure in which the lower end of the shaft  10  is formed in a polygonal shape and a polygonal coupling portion  21 , to which the lower end  12  of the shaft  10  is coupled, is formed at the putter head  20 . The lower end  12  and the coupling portion  21  may be formed so as to have a sawtooth structure (spline coupling), rather than the polygonal structure, so as to be coupled with each other. The lower end  12  of the shaft  10  and the coupling portion  21  are coupled to each other via a bolt (not shown) fastened to the lower end  12  of the shaft  10  through the bottom surface of the putter head  20  or the side surface of the upper end of the putter head at which the coupling portion  21  is formed in the state in which the lower end  12  is fitted in the coupling portion  21  such that the coupling angle therebetween is adjusted. Of course, the lower end  12  and the coupling portion  21  may be securely coupled to each other via a separate fixing means in the state in which the lower end is fitted in the coupling portion. 
     Since each of the lower end  12  of the shaft  10  and the coupling portion  21  is formed so as to have a polygonal structure or a sawtooth structure, as described above, it is possible to adjust the coupling angle of the putter head  20  having the hitting member  30  coupled thereto relative to the shaft  10 , as shown in  FIG. 6 . In the case in which each of the lower end  12  and the coupling portion  21  has a microscale sawtooth structure, it is possible to adjust the angle of the putter head  20  in microscale. 
     The operation of the variable golf putter according to the first embodiment of the present disclosure configured as described above will be described. 
     A user selects a hitting member  30  having one of different hitting surfaces  34 , e.g. a hitting member  30  having a spherical hitting surface  34 A, and couples the selected hitting member to the upper surface  23  of the putter head  20 , or selects a hitting member  30  having a planar hitting surface  34 B, and couples the selected hitting member to the upper surface  23  of the putter head  20 . That is, the user selects a hitting member  30  having a desired hitting surface  34 , and couples the selected hitting member to the putter head  20  using the fastening bolt  40 . 
     Subsequently, as shown in  FIG. 8 , the user may perform putting practice using the hitting member  30 , since the hitting surface  34  protrudes in the hitting direction through the incision portion  26  more than the hitting surface  24  of the putter head  20  when the hitting member  30  is coupled to the putter head  20 . 
     The user may couple the hitting member  30  having the spherical hitting surface  34 A to the putter head  20 , or may select the hitting member  30  having the planar hitting surface  34 B and may couple the selected hitting member to the putter head  20 , whereby it is possible to efficiently perform putting practice using various hitting surfaces. 
     In addition, since the seating surface of the hitting member  30  is seated on the upper surface  23  of the putter head  20 , the supporting surface  32 A is supported by the edge of the upper surface  23 , and the fastening bolt  40  is fastened to the coupling recess  32 V through the through hole  22 , a coupling state between the hitting member  30  and the putter hand  20  is securely maintained. Furthermore, the hitting member  30  does not move freely at the time of putting practice, and, since the supporting surface  32 A is supported by the edge  23 A of the upper surface  23 , stable hitting is possible without free movement at the time of hitting a golf ball. 
     In particular, since a hitting material  39  made of a different material than the hitting member  30  is provided integrally at the hitting surface  34 , it is possible to provide various hitting sensations and hitting sounds to the user. 
     Among the accompanying drawings,  FIGS. 9 to 12  are views showing a variable golf putter according to a second embodiment of the present disclosure.  FIG. 13  is a schematic plan view showing a use state of the variable golf putter shown in  FIGS. 9 to 12 . 
     As shown in  FIGS. 9 to 13 , the variable golf putter according to the second embodiment includes a putter head  20  coupled to the lower end  12  of a shaft  10 , the putter head having a head hitting surface  24 , and a hitting member  30  selectively coupled to the putter head  20 . 
     A through hole  22 , through which a fastening bolt  40  extends upwards from the bottom surface thereof, is formed in the putter head  20  so as to be stepped. An incision portion  26  configured to open a portion of the upper surface  23  of the putter head  20  in the hitting direction is formed in the central region of the head hitting surface  24  corresponding to the through hole  22 , i.e. equivalent to the region in which the through hole  22  is formed. A triangular to octagonal coupling protrusion  27  protrudes upwards from the upper surface  23  in which the through hole  22  is formed. 
     The hitting member  30  is formed in a golf ball shape or a polygonal shape, and hitting surfaces  34  having different shapes and different sizes are formed on the outer surface of the hitting member. A seating surface  32 , which is seated on the upper surface  23 , is formed at the bottom surface of the hitting member. A triangular to octagonal coupling recess  32 C is formed in the seating surface  32  such that the coupling protrusion  27  is inserted into and coupled to the coupling recess when the seating surface is seated on the upper surface  23 , and has coupling surfaces  32 C- 1  having the same directions as the hitting surfaces  34 . A screw fastening recess  32 B, to which the fastening bolt  40  is coupled by fastening when the coupling protrusion  27  is inserted into the coupling recess, is formed in the coupling recess  32 C. 
     The coupling protrusion  27  is inserted into and coupled to the coupling recess  32 C in the state in which the orientation of the hitting member  30  is set such that a hitting surface  34  selected from among the hitting surfaces  34  of the hitting member  30  is exposed through the incision portion  26 , and the fastening bolt  40  is fastened to the screw fastening recess  32 B of the coupling recess  32 C through the through hole  22 . As the result of this procedure, the hitting member  30  is coupled to the putter head  20 . 
     The hitting surface  34  of the hitting member  30  is constituted by a spherical hitting surface  34 A having the same curvature as a golf ball or a planar hitting surface  34 B. In the case in which the hitting surface of the hitting member is constituted by a planar hitting surface  34 B, a plurality of hitting members  30  is provided by size of the planar hitting surface  34 B, and is selectively coupled to the putter head  20 . This embodiment is identical to the previous embodiment except that a hitting material  39  made of a material different from the material of the hitting member  30  is provided integrally at the spherical hitting surface  34 A or the planar hitting surface  34 B. 
     In this embodiment, the coupling protrusion  27  is described as being formed in a quadrangular shape. However, the present disclosure is not limited thereto, and the coupling protrusion may be formed in any one of triangular to octagonal shapes. 
     Since the coupling protrusion  27  is formed on the putter head  20 , the coupling recess  32 C is formed in the hitting member  30 , and the hitting member  30  is coupled to the putter head via the coupling protrusion  27 , as described above, it is possible to more stably maintain a coupling state between the hitting member and the putter head  20 . 
     In the case in which the user selects the spherical hitting surface  34 A, from between the spherical hitting surface  34 A and the planar hitting surface  34 B of the hitting member  30 , the coupling protrusion  27  is inserted into the coupling recess  32 C of the hitting member  30  in such a manner that the coupling surface  32 C- 1  of the coupling recess  32 C coinciding with the spherical hitting surface  34 A faces the incision portion  26  such that the spherical hitting surface  34 A is exposed through the incision portion  26 , and then fastening is performed using the fastening bolt  40 , whereby it is possible to achieve secure coupling and to select the hitting surface  34 . 
     In other words, since the polygonal coupling recess  32 C having the plurality of coupling surfaces  32 C- 1  having the same directions as the hitting surfaces  34  is formed in the hitting member  30  having the plurality of hitting surfaces  34  formed thereon, and the polygonal coupling protrusion  27  is formed on the upper surface  23  of the putter head  20 , the user may select a preferred hitting surface  34 , from among the plurality of hitting surfaces  34 , and may couple the coupling protrusion  27  to the coupling recess  32 C in such a manner that the coupling surface  32 C- 1  coinciding with the selected hitting surface  34  faces the incision portion  26  such that the selected hitting surface  34  is exposed through the incision portion  26 . Consequently, it is possible for the user to perform hitting practice using the selected hitting surface  34 . 
     Since a plurality of hitting surfaces  34  is formed on a single hitting member  30  and each hitting surface  34  is configured to have a simple structure and to be selectively used, as described above, it is possible for the user to select and use one of the hitting surfaces  34  having various shapes and sizes. 
     In addition, the size of the hitting surface  34  may be selected, and then the hitting member  30  may be coupled to the putter head  20 , whereby it is possible to learn various hitting sensations. 
     Meanwhile, hitting material recesses  31  are formed in the hitting surface  34 , a hitting material  39  made of a material different from the material of the hitting member  30  is provided integrally in the hitting material recesses  31 , as in the previous embodiment. When the user performs hitting, therefore, it is possible to provide a hitting sensation and hitting sound other than when hitting is performed using a hitting member  30  made of a single kind of material. 
     Among the accompanying drawings,  FIGS. 11 and 13  show another embodiment of the variable golf putter according to the second embodiment of the present disclosure shown in  FIGS. 9 and 10 . 
     As shown in  FIGS. 9 and 13 , a hitting member  30  according to another embodiment is identical to the hitting member according to the previous embodiment except that a thickness adjustment recess  37  configured to make the thicknesses of the hitting surfaces  34  different from each other is formed around the coupling recess  32 C. That is, the thickness adjustment recess  37  is formed around the coupling recess  32 C of the hitting member  30 , and the thickness adjustment recess  37  is formed so as to have different widths W such that the hitting surfaces  34  have different thicknesses based on the coupling surfaces  32 C- 1 . Here, the thickness of each of the hitting surfaces  34  means the thickness between each of the hitting surfaces  34  and a corresponding one of the coupling surfaces  32 C- 1 . 
     As described above, the thickness adjustment recess  37  is formed so as to have different widths W such that the hitting surfaces  34  have different thicknesses. When the user selects one of the hitting surfaces  34  and hits a golf ball, therefore, it is possible to provide various hitting sensations and hitting sounds depending on the thickness of the hitting surface  34 . 
     Among the accompanying drawings,  FIG. 12  shows yet another embodiment of the variable golf putters according to the first to second embodiments of the present disclosure shown in  FIGS. 3 to 9 . As shown in  FIG. 12 , the variable golf putter has a seating recess  25  formed in the middle of the putter head  20  so as to be open in the hitting direction and in the upward direction, the seating recess  25  having a through hole  22  formed therethrough. This embodiment is identical to the previous embodiments except that, in the state in which a hitting member  30  having different shapes and sizes of hitting surfaces  34  is inserted into and seated in the seating recess  25 , the hitting member  30  is integrally coupled to the putter head  20  via a fastening bolt  40  fastened to the bottom surface of the hitting member  30  through the through hole  22  from below. Here, the seating recess  25  is formed so as to have the same shape as the hitting member  30  such that the hitting member  30  is inserted into and stably seated in the seating recess. 
     Since the hitting member  30  is inserted into the seating recess  25  of the putter head  20  and is coupled to the putter head via the fastening bolt  40 , as described above, it is possible to maintain a stable coupling state between the hitting member  30  and the putter head  20 . 
     Among the accompanying drawings,  FIG. 14  is a perspective view showing a variable golf putter according to a third embodiment of the present disclosure. 
     As shown in  FIG. 14 , the variable golf putter according to the third embodiment is identical to the variable golf putters according to the previous embodiments except that the variable golf putter includes a hitting member  30  having one end coupled to the lower end  12  of a shaft  10 , wherein a hitting surface  34  configured to hit a golf ball is formed on one side of the hitting member, and a spherical or planar practice hitting surface  34 - 1  is formed on the other side of the hitting member. That is, the variable golf putter according to the third embodiment has a structure in which the lower end  12  of the shaft  10  is coupled to one end of the hitting member  30  having the hitting surface  34  and the practice hitting surface  34 - 1  formed on opposite sides thereof. 
     In addition, the lower end  12  of the shaft  10  is formed in a polygonal shape, and a polygonal coupling portion  33 , to which the lower end  12  of the shaft  10  is coupled, is formed at the hitting member  30 . The lower end  12  of the shaft  10  and the coupling portion  33  are coupled to each other through fastening using a bolt  40 A fastened from the bottom surface of the hitting member  30  in the state in which the lower end  12  of the shaft  10  is fitted in the coupling portion  33  such that the coupling angle therebetween is adjusted. 
     Meanwhile, although not shown in the figure, the hitting material  39  described above may be provided in the hitting surface  34  or the practice hitting surface  34 - 1 . 
     Since the hitting member  30  is directly coupled to the shaft  10 , as described above, it is not necessary to provide a separate putter head  20 . In addition, since the hitting surface  34  is formed on one surface of the hitting member  30  and the practice hitting surface  34 - 1  is formed on the other surface of the hitting member, as described above, it is possible to provide convenience in which the user may hit a golf ball (putt) using the hitting surface  34  and may perform hitting practice using the practice hitting surface  34 - 1 . 
     Among the accompanying drawings,  FIG. 15  is an exploded perspective view showing a variable golf putter according to a fourth embodiment of the present disclosure, and  FIG. 16  is a sectional view showing a coupling state of the variable golf putter shown in  FIG. 15 . 
     As shown in  FIGS. 15 and 16 , the variable golf putter according to the fourth embodiment includes a putter head  20  having a coupling bar  210 , one end of which is coupled to the lower end  12  of a shaft  10 , the coupling bar extending in a horizontal direction, and a hitting member  30  having a hitting surface  34  configured to hit a golf ball, the hitting surface being formed on one side thereof, and a spherical or planar practice hitting surface  34 - 1  formed on the other side thereof, the hitting member being coupled to the putter head  20  and having a polygonal coupling portion  33 . The hitting member  30  is formed as a single body, and is coupled to the coupling bar  210  of the putter head  20 . In addition, the lower end  12  of the shaft  10  is formed in a polygonal shape and is inserted into the coupling portion  33  of the hitting member  30 , and a fastening bolt  40 A, which is inserted into a fastening bolt through-hole  21 A formed in the putter head  20 , is fastened to a screw hole (not shown) formed in the inner circumferential surface of the lower end  12  fitted in the coupling portion  33 . As a result, the shaft  10 , the hitting member  30 , and the putter head  20  are integrated. Of course, the lower end  12  and the putter head  20  may be coupled to each other through a fixing structure other than the fastening bolt  40 A. 
     Meanwhile, in this embodiment, it is possible to adjust the coupling angle between the hitting member  30  and the shaft  10  based on the coupling angle between the lower end  12  and the coupling portion  33 . That is, the angle at which the lower end  12  of the shaft  10  is inserted into the polygonal coupling portion  33  is adjusted, and then the bolt  40 A is fastened to the lower end  12  from the lower surface of the putter head  20 , whereby the coupling angle between the hitting member and the shaft  10  is set. 
     This embodiment is identical to the previous embodiments except for the coupling structure described above. 
     Here, a hitting material  39  made of a material different from the material of the hitting member  30  may be provided in the hitting surface  34  and the practice hitting surface  34 - 1 , as previously described. 
     In addition, an insertion recess  35 , into which the coupling bar  210  is inserted, is formed in the bottom surface of the hitting member  30 , and the fastening bolt  40  is fastened to a screw hole formed in the insertion recess  35  of the hitting member  30  through the coupling bar  210  from the lower surface thereof in the state in which the coupling bar  210  is inserted in the insertion recess  35 , whereby the hitting member  30  and the coupling bar  210  may be securely coupled to each other. 
     In addition, as previously described, the hitting member  30  is coupled to the coupling bar  210  of the putter head  20  through a fitting structure and a fastening structure, whereby it is possible to select and use various shapes and sizes of hitting members  30 . Furthermore, since the hitting surface  34  is formed on one surface of the hitting member  30  and the practice hitting surface  34 - 1  is formed on the other surface of the hitting member, it is possible to provide convenience in which the user may hit (putt) a golf ball using the hitting surface  34  and may perform hitting practice using the practice hitting surface  34 - 1 . 
     Among the accompanying drawings,  FIG. 17  is an exploded perspective view showing another embodiment of the variable golf putter shown in  FIG. 15 . 
     As shown in  FIG. 17 , another embodiment of the variable golf putter shown in  FIGS. 15 and 16  is identical to the fourth embodiment described above except that two to five hitting members  30  having different sizes and shapes are individually formed and are coupled to the coupling bar  210  such that the hitting surface  34  and the practice hitting surface  34 - 1  are selected. In this case, it is natural that insertion recesses  35 , into which the coupling bar  210  is inserted so as to be coupled thereto, are formed in the bottom surfaces of the individual hitting members  30 . 
     In the case in which the hitting members  30  are individually formed, as described above, the individual hitting members  30  may be made of different materials. Since the hitting members  30  are made of different materials, as described above, it is possible for the user to select a hitting member  30  made of a material that provides a desired hitting sensation and to perform hitting practice. 
     Since the hitting members  30  are individually formed so as to have different sizes and shapes, as shown in  FIG. 17 , it is possible to provide convenience in which the user may select a hitting member  30  according to personal preference and may perform hitting (putting) practice. 
     Meanwhile, as shown in  FIGS. 18, 19, and 20 , in the hitting member  30  according to the fourth embodiment described above, a hitting material  39  made of a material different from the material of the hitting member  30  may be provided at the hitting surface  34 . 
     For example, in the case in which the hitting member  30  is made of iron, the hitting material  39  may be made of copper or aluminum, whereby it is possible to provide various hitting sensations to the user. That is, hitting material recesses  31  are formed in the hitting surface  34  and the practice hitting surface  34 - 1 , and the hitting material recesses  31  are filled with a metal material or a hard synthetic resin material different from the material of the hitting member  30 , or the hitting material is integrally formed with the hitting member through insert injection molding. In particular, as shown in  FIGS. 18 and 19 , protrusions  31 - 1  may be formed on the bottoms of the hitting material recesses  31  formed in the hitting surface  34 , and gaps between the protrusions  31 - 1 , i.e. the hitting material recesses  31 , may be filled with the hitting material  39  so as to be integrated, or the hitting material may be integrally formed with the hitting member through insert injection molding. 
     As described above, the hitting material  39  is provided integrally at the hitting surface  34  and the practice hitting surface  34 - 1 . When the user hits a golf ball using the hitting surface having the hitting material  39 , therefore, it is possible to obtain a hitting sensation and hitting sound different from when the user hits the golf ball using a hitting surface  34  made of only a single metal. According to this embodiment, it is possible to provide various hitting sensations and hitting sounds to the user. 
     Meanwhile, among the accompanying drawings,  FIG. 20  is a view showing another embodiment of the hitting member shown in  FIG. 17 . 
     As shown in  FIG. 20 , this embodiment is identical to the previous embodiments except that, in the case in which the hitting member  30  is formed so as to have a spherical shape (a spherical surface) and a practice hitting surface  34  is formed at the outer circumference  34 - 3  of the spherical shape, a spherical hitting portion  34 - 2  having curvature smaller than the curvature of the outer circumference  34 - 3  of the hitting member  30  is formed at the practice hitting surface  34 , and an auxiliary hitting surface  34 - 5  is formed at the spherical hitting portion  34 - 2 . 
     That is, in the case in which the spherical hitting portion  34 - 2 , which has small curvature, is formed at the practice hitting surface  34  of the outer circumference  34 - 3  of the hitting member  30 , and the auxiliary hitting surface  34 - 5  is formed at the spherical hitting portion  34 - 2 , whereby the distance between the center of the insertion recess  35  and an imaginary hitting surface is preset, it is possible to increase or decrease the area of the auxiliary hitting surface  34 - 5 . That is, in the case in which the distance between the center of the insertion recess  35  and the imaginary hitting surface is preset, it is possible to form a hitting member  30  configured such that the area of the hitting surface is increased or to form a hitting member  30  configured such that the area of the hitting surface is decreased without changing the distance between the center of the insertion recess  35  and the imaginary hitting surface. 
     In other words, in the case in which the distance between the center of the insertion recess  35  and the imaginary hitting surface is preset at the time of manufacture of the hitting member  30 , the spherical hitting portion  34 - 2  having curvature smaller than the curvature of the hitting member  30  is formed at the practice hitting surface  34  so as to be protrude, and the auxiliary hitting surface  34 - 5  is formed at the hitting region of the spherical hitting portion  34 - 2 , as shown in  FIG. 20 . At this time, it is possible to increase or decrease the area of the auxiliary hitting surface  34 - 5  by increasing or decreasing the curvature of the spherical hitting portion  34 - 2 . In the above structure, it is possible to obtain a hitting member  30  configured such that the auxiliary hitting surface  34 - 5  has different areas without changing the distance between the center of the insertion recess  35  and the imaginary hitting surface. This structure is shown in  FIG. 20 . 
     In addition, a decorative member J made of a jewel or a quasi-jewel, such as sapphire or cubic zirconia, in order to increase the value of the hitting member  30  and to improve visibility of the hitting member, may be provided at the upper surface of the hitting member  30 . The decorative member J may have a screw portion configured to be fastened to a screw hole formed in the hitting member  30  such that the decorative member is coupled to the hitting member  30  through a fastening structure, or may be coupled to the hitting member through a separate coupling structure. 
     Among the accompanying drawings,  FIG. 21  is an exploded perspective view showing a variable golf putter according to a fifth embodiment of the present disclosure,  FIG. 22  is a sectional view showing a coupling state of the variable golf putter shown in  FIG. 21 , and  FIG. 23  is a plan view showing a use state of the variable golf putter shown in  FIG. 21 . 
     As shown in  FIGS. 21 to 23 , the variable golf putter according to the fifth embodiment is identical to the variable golf putters according to the previous embodiments described above except for the following construction. 
     That is, the variable golf putter includes a putter head  200  coupled to the lower end  12  of a shaft  10 , wherein the putter head  200  includes a first hitting member  300 A which is formed in a spherical shape, such as a golf ball shape, and to which the lower end of the shaft  10  is coupled, a second hitting member  300 B which is formed in a spherical shape, such as a golf ball shape, and which is coupled to the side surface of the first hitting member  300 A in a horizontal direction so as to be located on a straight line together with the first hitting member  300 A, a third hitting member  300 C which is formed in a spherical shape, such as a golf ball shape, and which is coupled to the side surface of the second hitting member  300 B in the horizontal direction so as to be located on a straight line together with the first hitting member  300 A and the second hitting member  300 B, and a coupling rod  400  having one end to which a nut is fastened after the coupling rod extends through the first hitting member  300 A, the second hitting member  300 B, and the third hitting member  300 C and the other end to which the shaft  10  is fastened, the coupling rod being configured to integrate the first hitting member  300 A, the second hitting member  300 B, and the third hitting member  300 C. 
     In addition, a spherical hitting surface  320  having the same curvature as a golf ball and planar hitting surfaces  340  are formed at each of the first hitting member  300 A, the second hitting member  300 B, and the third hitting member  300 C, wherein the planar hitting surfaces  340  are formed so as to have different sizes. That is, the outer circumferential surface of each of the hitting members  300 A,  300 B, and  300 C is divided into four parts such that one of the parts constitutes a spherical hitting surface  320  and the other parts constitute planar hitting surfaces  340  having different sizes. The reason that a single hitting member is formed so as to have a plurality of different hitting surfaces as described above is that it is necessary to allow a user to select and use hitting surfaces having various sizes and shapes (a spherical shape or a planar shape). 
     The first hitting member  300 A, the second hitting member  300 B, and the third hitting member  300 C are made of different materials, and a hitting material  390  made of a material different from the materials of the first hitting member  300 A, the second hitting member  300 B, and the third hitting member  300 C is provided integrally at the spherical hitting surface  320  and the planar hitting surfaces  340 , wherein hitting material recesses  310  formed in the spherical hitting surface  320  and the planar hitting surfaces  340  are filled with the hitting material  390 , or the hitting material is integrally formed with the hitting members through insert injection molding. 
     In addition, a position changing means  500  configured to change positions of the second hitting member  300 B and the third hitting member  300 C, to select the spherical hitting surface  320  and the planar hitting surfaces  340 , and to change the hitting surfaces  320  and  340  depending on whether the user is a right-handed person or a left-handed person is provided at each of the first hitting member  300 A, the third hitting member  300 C, and opposite surfaces of the second hitting member  300 B that face the first hitting member  300 A and the third hitting member  300 C. 
     The position changing means  500  includes a triangular to octagonal connection and coupling member  510  having a predetermined length and a triangular to octagonal positioning recess  520  formed in a corresponding one of the opposite surfaces of the first hitting member  300 A, the second hitting member  300 B, and the third hitting member  300 C such that the connection and coupling member  510  is coupled to the positioning recess  520  by insertion. 
     In this embodiment, the polygonal connection and coupling member  510  and the polygonal positioning recess  520  are described as being formed so as to have a quadrangular shape, and the minimum number of connection and coupling members  510  is two. The reason for this is that other hitting members are connected and coupled to opposite surfaces of a middle hitting member. 
     The first hitting member  300 A, the second hitting member  300 B, and the third hitting member  300 C may be made of the same material as a golf ball, or may be made of a metal material or a synthetic resin material. 
     In addition, each of the connection and coupling members  510  has a through hole, through which the coupling rod  400  extends. 
     The operation of the variable golf putter according to the fifth embodiment configured as described above will be described. 
     As shown in  FIGS. 21 to 23 , in the state in which the shaft  10  is coupled to the first hitting member  300 A, the second hitting member  300 B is located at one side of the first hitting member  300 A, and the third hitting member  300 C is located at one side of the second hitting member  300 B, one end of a connection and coupling member  510 A is coupled to the positioning recess  520  of the first hitting member  300 A by insertion, and the other end of the connection and coupling member is coupled to the positioning recess  520  formed in one surface of the second hitting member  300 B by insertion. In addition, one end of another connection and coupling member  510 B is coupled to the positioning recess  520  formed in the other surface of the second hitting member  300 B by insertion, and the other end of the connection and coupling member is coupled to the positioning recess  520  formed in one surface of the third hitting member  300 C by insertion. 
     Subsequently, the coupling rod  400  extends through the first hitting member  300 A, the first connection and coupling member  510 A, the second hitting member  300 B, the second connection and coupling member  510 B, and the third hitting member  300 B. Thereafter, nuts are fastened to the positioning recess  520  formed in the other surface of the third hitting member  300 C and to the portion of the coupling rod  400  exposed in the positioning recess  520  formed in the other surface of the first hitting member  300 A to integrate the first, second, and third hitting members  300 A,  300 B, and  300 C. 
     In this state, as shown in  FIG. 23 , a right-handed user may perform putting practice using a putter having the putter head  200  including the first, second, and third hitting members  300 A,  300 B, and  300 C. At this time, the spherical hitting surface  320  or the planar hitting surface  340  of the middle hitting member is used as a hitting surface configured to hit a golf ball. 
     Meanwhile, in order to select the spherical hitting surface  320  from among the hitting surfaces  320  and  340 , the user unfastens the nuts, by which the first, second, and third hitting members  300 A,  300 B, and  300 C are integrated, from the coupling rod  40 , separates the connection and coupling members  510 A and  510 B from the middle hitting member, i.e. the second hitting member  300 B, rotates the second hitting member  300 B such that the spherical hitting surface  320  is oriented in the hitting direction, and fastens the nuts to opposite ends of the coupling rod  40  as described above to integrate the first, second, and third hitting members  300 A,  300 B, and  300 C again. 
     In the case in which the user is a left-handed person, the user may perform hitting after changing the hitting direction, as shown in  FIG. 24 . That is, since the spherical and planar hitting surfaces  320  and  340  are formed on a plurality of surfaces of each of the hitting members  300 B and  300 C, the left-handed user may hold a club, and may perform hitting in the state of changing the hitting direction. 
     In the golf putter for practice according to this embodiment, as described above, the hitting surface may be selected by selecting the hitting members  300 B and  300 C. Consequently, it is possible to more efficiently perform putting practice using various hitting surfaces  320  and  340 . In particular, the hitting surfaces  320  and  340  are formed in opposite directions such that the hitting direction is not fixed to one side, whereby the left-handed user as well as the right-handed user may easily perform putting practice. 
     In addition, a hitting material  390  made of a material different from the materials of the hitting members  300 B and  300 C is provided in the spherical hitting surface  320  and the planar hitting surfaces  340 , and therefore it is possible to provide various hitting sensations to the user at the time of hitting practice. 
     Among the accompanying drawings,  FIG. 25  is an exploded perspective view showing a variable golf putter according to a sixth embodiment of the present disclosure.  FIG. 26  is a perspective view showing a coupling state of the variable golf putter shown in  FIG. 25 .  FIG. 27  is a sectional view taken along line A-A of  FIG. 26 . 
     As shown in  FIGS. 25 to 27 , the variable golf putter according to the sixth embodiment includes a putter head  20  having a shaft coupling hole  21 , to which the lower end  12  of a shaft  10  is coupled, and a head hitting surface  24  and a hitting member selectively coupled to the putter head  20 . 
     A through hole  22 , through which a fastening bolt  40  extends upwards from the bottom surface thereof, is formed in the putter head  20  so as to be stepped. An incision portion  26  configured to open a portion of the upper surface  23  of the putter head  20  in the hitting direction is formed in the central region of the head hitting surface  24  corresponding to the through hole  22 . A coupling portion  23 A is formed around the through hole  22 . The coupling portion  23 A has a quadrangular section. 
     Shaft coupling holes  21  of the putter head  20  are formed in opposite sides of the putter head  20  such that a right-handed person or a left-handed person selects one of the shaft coupling holes and couples the shaft  10  to the selected shaft coupling hole. The lower end  12  of the shaft  10  and the shaft coupling hole  21  may be formed in a polygonal shape or may be formed so as to be coupled to each other through spline coupling, whereby the coupling angle between the putter head  20  and the shaft  10  may be adjusted. 
     A hitting surface  34  may be formed at one or each of the outer surfaces of the hitting member  30 . In this embodiment, however, a description will be given on the assumption that a hitting surface  34  is formed at one surface of the hitting member and an auxiliary hitting surface  34  is formed at the other surface of the hitting member. A coupling recess H, to which the coupling portion  23 A is coupled by insertion, is formed in the bottom surface of the hitting member so as to be open downwards. A screw fastening recess H 1 , to which a fastening bolt  40  is fastened, is formed in the bottom surface of the coupling recess H. 
     A hitting sound generation recess  34 - 4  configured to generate a hitting sound when a golf ball is hit by the entirety of the hitting surface  34  or the region of the hitting surface  34  corresponding to a positive hitting point P is formed in the hitting member  30 . As shown in  FIGS. 27 and 28 , the hitting sound generation recess  34 - 4  may be formed in a region corresponding to the hitting surface  34  or the region of the hitting surface  34  corresponding to the positive hitting point P so as to be open toward the bottom, the side, or the top of the hitting member  30  or toward a coupling recess  35 . Preferably, the hitting sound generation recess is open toward the bottom of the hitting member  30 . 
     The reason that the hitting sound generation recess  34 - 4  is formed in the hitting member  30  as described above is that a bright hitting sound is generated when a golf ball is hit at the positive hitting point P and a dull hitting sound is generated when the golf ball is hit by the region of the hitting member deviating from the positive hitting point P, whereby it is possible to audibly determine and recognize whether correct hitting has been performed. 
     Although not shown in the figures, the hitting sound generation recess  34 - 4  may be filled with a hitting material made of a metal material or a synthetic resin material different from the material of the hitting member  30 , the hitting material may be coupled to the hitting sound generation recess by insertion, or the hitting material may be integrally formed with the hitting member  30  through insert injection molding. Integration between the hitting material and the hitting member is performed in order to generate various hitting sounds. 
     In addition, as shown in  FIGS. 20, 25, and 26 , the hitting sound generation recess  34 - 4  may not be formed in the hitting member  30 . That is, the hitting sound generation recess  34 - 4  may be selectively formed as needed. 
     The hitting member  30  may be formed in the shape of a sphere, a hemisphere, a quadrangle, or a combination of a polygon, including a quadrangle, and a sphere. 
     The hitting member  30  and the putter head  20  configured as described above are coupled to each other through the following structure. That is, the fastening bolt  40  is fastened to the screw fastening recess H 1  through the through hole  22  in the state in which the coupling portion  23 A is inserted into and coupled to the coupling recess H such that the hitting surface  34  or the auxiliary hitting surface  34 - 6  protrudes through the incision portion  26  more than the head hitting surface  24  or coincides with the head hitting surface  24 , whereby the hitting member  30  is replaceably coupled to the putter head  20 . 
     In a hitting member  30  according to another embodiment, as shown in  FIGS. 25 to 27 , a mark C configured to indicate the hitting direction is formed on the outer circumferential surface of the hitting member  30  in the form of a plurality of recesses or a line. The user may recognize the putting direction through the mark C at the time of putting. To this end, the marks C are formed in a line. 
     In a hitting member  30  according to yet another embodiment, as shown in  FIGS. 25 to 27 , a decorative member J 1  made of a jewel or a quasi-jewel is provided at the upper surface of the hitting member. A portion of the decorative member J 1  may be coupled to an insertion recess formed in the center of the upper surface of the hitting member  30  by insertion, or a male-screw fastening portion provided at the decorative member J 1  may be coupled to a screw hole formed in the upper surface of the hitting member by fastening. This structure is configured to easily replace or exchange the decorative member J 1 . In this case, the decorative member J 1  may be coupled to the recess-shaped mark C, or may be formed at a position other than the mark C. 
     Also, in the case in which the hitting member  30  is formed so as to have the shape of a sphere, a hemisphere, or a combination of a polygon and a sphere, the total size (diameter) of the hitting member is set, a hitting position P 2  for hitting is formed at the outer circumference of the sphere, and the distance L between the center P 1  of the hitting member  30  and the hitting position P 2  is preset, a hemispherical auxiliary member  34 - 6  is formed at the hitting surface  34  formed at the outer circumference thereof so as to protrude and an auxiliary hitting surface  34 - 5  is formed at the hemispherical auxiliary member  34 - 6  such that the area of the hitting surface is increased or decreased, as shown in  FIGS. 25 to 27 . 
     That is, in the case in which the distance L between the center P 1  of the hitting member  30  and the hitting position P 2  is preset and the size of the hitting member  30  is preset, as shown in  FIG. 27 , it is not possible to increase or decrease the area of the hitting surface  34  formed at the outer circumference of the sphere. In order to solve this, the hemispherical auxiliary member  34 - 6  is formed at the hitting surface  34  formed at the outer circumference of the sphere so as to protrude. In addition, the auxiliary hitting surface  34 - 5  is formed at the outer circumference of the auxiliary member  34 - 6  corresponding to the hitting position P 2  so as to be flat. 
     In other words, in order to form a hitting member  30  configured such that the area of the auxiliary hitting surface  34 - 5  is large, the size of the auxiliary member  34 - 6  is increased such that the auxiliary hitting surface  34 - 5  is formed at the top region (hitting position) of the auxiliary member  34 - 6  so as to have a large area. In order to form a hitting member  30  configured such that the area of the auxiliary hitting surface  34 - 5  is small, the size of the auxiliary member  34 - 6  is decreased, and the auxiliary hitting surface  34 - 5  is formed at the top region (hitting position) of the auxiliary member  34 - 6  so as to have a small area. Through the above procedures, hitting members  30  including auxiliary hitting surfaces  34 - 5  having different sizes (areas) may be provided. 
     That is, it is possible to obtain a hitting member  30  configured such that the area of the auxiliary hitting surface  34 - 5  is large by increasing the area of the auxiliary hitting surface  34 - 5  or to obtain a hitting member  30  configured such that the area of the auxiliary hitting surface  34 - 5  is small by decreasing the area of the auxiliary hitting surface  34 - 5  without changing the distance L between the hitting position P 2  for hitting and the center P 1  of the hitting member  30 . 
     It is obvious to a person having ordinary skill in the art that, although the specific embodiments of the present disclosure have been shown and described above, the present disclosure is not limited to the described embodiments and various changes and modifications are possible without departing from the idea and scope of the present disclosure. Thus, it is intended that the changes or the modifications should not be understood independently of the technical spirit or prospect of the present disclosure and that modified embodiments fall within the scope of the claims of the present disclosure. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure is configured to selectively couple hitting members having various hitting areas to a putter head in order to perform hitting practice, and may provide various hitting sensations to a user. Consequently, the present disclosure is usefully applicable to the golf industry and thus has industrial applicability.