Patent Publication Number: US-2017348578-A1

Title: Portable cocking practice device

Description:
TECHNICAL FIELD 
     The present application claims priority to Korean Patent Application No. 10-2014-0193276 filed in the Korean Intellectual Property Office on Dec. 30, 2014, the entire contents disclosed in the description and drawings of which are incorporated herein by reference. 
     The present invention relates to a portable cocking practice device and, more particularly, to a portable cocking practice device while increasing similarity to the actual golf swing and enabling a cocking practice according to each golf club and also improving a user&#39;s convenience and portability. 
     BACKGROUND ART 
     Recently, with an increase of the publicity of golf sports and the spread of a so-called indoor golf simulator corresponding to a golf simulation system, people who try to enjoy golf as leisure sports are suddenly increasing. In line with such a trend, the general public interest in a systematic and efficient golf swing posture is increasing daily and the demand for golf swing practice devices is also suddenly increasing. 
     In general, a golf swing is a motion mechanism, including a take back in which a club is taken back in a direction opposite a target, a back swing in which cocking for breaking the wrist is performed, a down swing in which uncocking for releasing the cocked wrist while the club is swung toward the target through transition at the top position of the back swing is performed, an impact in which a ball is hit by the head of the club, a follow through in which the club continues to proceed along the swing path after the impact, and a finish motion in which the swing is finished. 
     The cocking and uncocking operations of the operation of the golf swing are core operation for increasing the driving distance of a ball by maximizing the head speed of a club during the swing. In order for the cocking and uncocking operations to be efficiently performed, so-called delay hitting in which the ball is hit while hands that hold grips are ahead of the head of the club on a swing plane must be performed. That is, lagging in which the cocking state is maintained right before the impact as much as possible is required. Common amateur players require accurate understanding of the corresponding mechanism and a great amount of practice in order to correctly performing such cocking and uncocking operations. 
     Meanwhile, in the golf sports,  14  clubs having various lengths and weights from a driver to a sand wedge are used in average. The position of a ball where each club is located ahead of a golfer upon addressing is different. As a result, an impact point of time at which a corresponding head comes into contact with a ball is different for each club. Accordingly, a golfer who tries to improve his or her golf skill must be accustomed to a swing by performing a separate cocking practice for each club having a different length, weight and impact point of time. 
     As disclosed in Korean Patent Application Publication No. 1020070031370, etc., however, the existing golf swing practice devices are problematic in that they do not separately take into consideration cocking and uncocking operation practices, that is, the core operation of an efficient golf swing, and do not propose a technology capable of improving a similarity with an actual golf swing. 
     More specifically, as disclosed in Korean Patent Application Publication No. 1020100129362, etc., the existing golf swing practice devices has a problem in that they do not propose a technology which enables cocking practices to be performed using a single practice device with respect to each of golf clubs which have different lengths, weights and impact points of time and range from the driver to the sand wedge. Furthermore, they do not propose a technology which provides a feeling similar to an actual golf club upon practicing a swing and also improves portability while moving. 
     SUMMARY OF THE INVENTION 
     The present disclosure provides a portable cocking practice device in which enables a user&#39;s to have a feeling of an impact like an actual golf swing and also to check whether correct cocking and uncocking operations are performed in person. 
     Furthermore, the present disclosure provides a portable cocking practice device in which enables cocking practices for each golf club in accordance with golf clubs having various lengths from a driver to a sand wedge and also improves user convenience and portability. 
     Furthermore, the present disclosure provides a portable cocking practice device in which increases a similarity with an actual golf swing in which an impact point of time is different for each golf club and improves a cocking practice effect. 
     According to an exemplary embodiment of the present disclosure provides a portable cocking practice device may include a first shaft part having a hollow therein and an having opening at one end thereof, which is connected to the hollow; a second shaft part inserted and fixed into the hollow of the first shaft part through the opening part of the first shaft part over the entire length or a part of length thereof; and an rod withdrawing part received inside the second shaft part so as to withdraw a given rod out of the second shaft part by an uncocking operation of a golf swing, wherein the second shaft part may include a second shaft body which has an insertion length indication part having the insertion length of each golf club that is a subject of a cocking practice indicated in an outer face and accommodates an rod withdrawing part therein so that a rod of the rod withdrawing part is given rod out of through an opening part at one end; and insertion position adjustment means for fixing the second shaft body inserted into the first shaft part to the first shaft part at a corresponding insertion position in response to the insertion length of each golf club indicated in the insertion length indication part. 
     In an embodiment, the first shaft part may include a first shaft body of a hollow pipe form into which the second shaft part is inserted through an opening part at one end and a grip part which is coupled to the other end of the first shaft body and has protrusions for a grip which guide a grip in position on an outer face. 
     In an embodiment, the insertion position adjustment means may include a bolt part for adjusting an insertion position which is coupled and fixed to the second shaft body and a nut part for adjusting an insertion position which is screwed onto the bolt part for adjusting an insertion position and fixed to the inner circumference surface of the first shaft part. 
     In an embodiment, the nut part for adjusting an insertion position may have guide protrusions which guide a movement in the insertion direction of the second shaft part within the first shaft part in an outer circumference surface. 
     In an embodiment, the first shaft part may have guide grooves corresponding to the guide protrusions in an inner circumference surface. 
     In an embodiment, the rod withdrawing part may include an withdrawing rod which has one end accommodated in the second shaft body and the other end located outside the second shaft body; a head part which has a diameter greater than the internal diameter of the second shaft body and is coupled to the other end of the withdrawing rod outside the second shaft body; and an elastic member which is disposed within the second shaft body to restrict the one end of the withdrawing rod by an elastic force and withdraw a given rod out of the second shaft body in a specific length by an uncocking operation of a golf swing. 
     In an embodiment, the head part may have a plurality of air resistance faces which increases air resistance upon playing a golf swing. 
     In an embodiment, the elastic member may be a coil type spring member having one end clamped to the one end of the withdrawing rod by a specific coupling member and the other end fixed within the second shaft body by a specific fixing member. 
     In an embodiment, the withdrawing rod may have screw threads in at least part of an outer circumference surface. The head part may have a through hole screwed onto the screw threads of the withdrawing rod and may be screwed onto the withdrawing rod through the through hole to withdraw a given rod out of the second shaft body in a specific length along a screw coupling degree. 
     In an embodiment, the portable cocking practice device may further include a member for adjusting an impact point of time which is disposed in the withdrawing rod portion between the head part coupled to the other end of the withdrawing rod and the second shaft body and withdraw a given rod out of the second shaft body in a specific length by separating the head part and the second shaft body. 
     Advantageous Effects 
     In accordance with the present invention, a user&#39;s can have a feeling of an impact like an actual golf swing and also check whether the user takes a correct cocking and uncocking operation in person because the rod within the shaft coupled to a head is withdrawn when the user takes the uncocking operation of a normal golf swing. 
     In particular, cocking practices for each golf club are made possible and a user&#39;s convenience and portability can also be improved because the length and weight of the shaft can be adjusted in response to golf clubs having various lengths and weights from a driver to a sand wedge. 
     Furthermore, a similarity with an actual golf swing in which an impact point of time is different for each golf club can be increased and a cocking practice effect can be improved because an impact point of time at which the rod within the shaft is withdrawn as much as possible can be adjusted. 
     Furthermore, a person having ordinary skill in the art to which the present invention pertains will obviously understand that various embodiments according to the present invention can solve several objects not described above from the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view a portable cocking practice device according to an exemplary embodiment of the present invention. 
         FIG. 2  is an exploded perspective view a portable cocking practice device according to an exemplary embodiment of the present invention. 
         FIG. 3  is a perspective view an example of a second shaft part. 
         FIG. 4A  is a cross-sectional view an example of a first shaft part into which a nut part for adjusting an insertion position has been inserted. 
         FIG. 4B  is a cross-sectional view showing another example of the first shaft part into which the nut part for adjusting an insertion position has been inserted. 
         FIG. 5  is a perspective view a mode for a driver practice in the portable cocking practice device according to an exemplary embodiment of the present invention. 
         FIG. 6  is a perspective view a portable mode in the portable cocking practice device according to an exemplary embodiment of the present invention. 
         FIG. 7A  is a cross-sectional view an example of a rod withdrawing part. 
         FIG. 7B  is a cross-sectional view the maximum withdraw state of the rod withdrawing part. 
         FIG. 8  is a perspective view the state upon uncocking of the portable cocking practice device according to an exemplary embodiment of the present invention. 
         FIG. 9A  is a perspective view an example of a member for adjusting an impact point of time. 
         FIG. 9B  is a plan view the member for adjusting an impact point of time in  FIG. 9A . 
         FIG. 10  is a diagram a method for adjusting an impact point of time of the portable cocking practice device according to an exemplary embodiment of the present invention. 
         FIG. 11  is a diagram a method for adjusting an impact point of time of the portable cocking practice device according to another exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, preferred embodiments of the present invention are described in detail with reference to the accompanying drawings in order to clarify means for solving the technical objects of the present invention. In the accompanying drawings, the same reference numerals denotes the same member. In describing the present invention, a detailed description of a related known technology will be omitted if it is deemed to make the gist of the present invention unnecessarily vague. Furthermore, the following terms are terms defined by taking into consideration functions in the present invention and may be changed depending on an intention or practice of a designer, a manufacturer, etc. Accordingly, the definition of the terms should be made based on contents over the entire description. 
       FIG. 1  shows a portable cocking practice device according to an exemplary embodiment of the present invention in a perspective view form. 
       FIG. 2  shows the portable cocking practice device according to an exemplary embodiment of the present invention in an exploded perspective view form. 
     As shown in  FIGS. 1 and 2 , the portable cocking practice device according to the present invention may includes a first shaft part  100 , a second shaft part  200  and a rod withdrawing part  300 . 
     The first shaft part  100  having a hollow therein and having an opening part connected to the hollow at one end. The first shaft part  100  may include a first shaft body  110  and a grip part  120 . In this case, the first shaft body  110  may be configured in the form of a hollow pipe into which the second shaft part  200  is inserted through the opening part at one end. Furthermore, the grip part  120  is coupled to the other end of the first shaft body  110  and may include protrusions  122  and  124  for a grip which guide a user&#39;s grip in position on the outer face of the grip part. The protrusions for a grip allow a user&#39;s to take a correct grip posture, thus being capable of improving a golf swing exercise effect. 
     Some or the entire length of the second shaft part  200  is inserted into the hollow of the first shaft part  100  through the opening part of the first shaft part  100 . The second shaft part  200  may include a second shaft body  210  and insertion position adjustment means. In this case, the second shaft body  210  has an insertion length indication part  212  in which the insertion length of each golf club, that is, a target of cocking practices, is indicated in the outer face of the second shaft body. The second shaft body  210  accommodates the rod withdrawing part  300  therein so that a specific rod of the rod withdrawing part  300  is drawn out through the opening part at one end. To this end, the second shaft body  210  may be configured in the form of a hollow pipe. Furthermore, the insertion position adjustment means fixes the second shaft body  210 , inserted into the first shaft part  100  depending of the insertion length of each golf club indicated in the insertion length indication part  212 , to the first shaft part  100  at a corresponding insertion position. In an embodiment, the insertion position adjustment means may include a bolt part  220  for adjusting an insertion position and a nut part  230  for adjusting an insertion position. In this case, the bolt part  220  for adjusting an insertion position is coupled to the other end of the second shaft body  210  and fixed thereto. Furthermore, the nut part  230  for adjusting an insertion position is screwed onto the bolt part  220  for adjusting an insertion position and fixed to the inner circumference surface of the first shaft part  100 . To this end, the diameter of a portion that belongs to the bolt part  220  for adjusting an insertion position and that is inserted into the nut part  230  for adjusting an insertion position may be configured to increase as screw coupling with the nut part  230  for adjusting an insertion position proceeds. The nut part  230  for adjusting an insertion position may be made of a specific elastic material. 
     In another embodiment, the insertion position adjustment means may include a specific trapping groove (not shown) or a trapping protrusion (not shown). When the second shaft body  210  is inserted into the first shaft part  100 , the trapping groove or the trapping protrusion may be configured to be coupled to a specific trapping protrusion or trapping groove provided in the inner circumference surface of the first shaft part  100  and to fix the second shaft body  210  to the first shaft part  100 . 
     As will be described hereinafter, a user&#39;s may set a mode for a golf club on which cocking practices are to be performed by properly inserting the second shaft part  200  into the first shaft part  100  with reference to the insertion length indication part  212  of the second shaft part  200  and fixing the second shaft part  200  to the first shaft part  100  using the insertion position adjustment means. 
       FIG. 3  shows an example of the second shaft part in a perspective view form. As shown in  FIG. 3 , when a user&#39;s attempts a cocking practice for a specific club, the user inserts the second shaft part  200  into the first shaft part  100  up to an indication corresponding to the corresponding club with reference to the insertion length indication part  212  provided in the second shaft body  210 . Next, a user&#39;s turns the second shaft part  200  to screw the bolt part  220  for adjusting an insertion position and the nut part  230  for adjusting an insertion position so that the outer circumference surface of the nut part  230  for adjusting an insertion position is closely fixed to the inner circumference surface of the first shaft part  100 . To this end, the outer circumference surface of the nut part  230  for adjusting an insertion position may have guide protrusions  234  for guiding a movement in the insertion or withdrawing direction of the second shaft part  200  within the first shaft part  100 . 
       FIG. 4A  shows an example of the first shaft part into which the nut part for adjusting an insertion position has been inserted in a cross-sectional view form. 
     As shown in  FIG. 4A , screw threads for screwing with the bolt part  220  for adjusting an insertion position have been formed in the inner circumference surface  232  of the nut part  230  for adjusting an insertion position. The guide protrusions  234  may be formed in the outer circumference surface of the nut part  230 . The guide protrusions  234  are formed to guide a movement in the insertion or withdraw direction of the second shaft part  200  by an external force through contact with the inner circumference surface of the first shaft part  100 , that is, the inner circumference surface of the first shaft body  110 , and to have friction enough for screwing if the bolt part  220  for adjusting an insertion position has been released. In contrast, the diameter of the nut part  230  for adjusting an insertion position as the screwing between the bolt part  220  for adjusting an insertion position and the nut part  230  for adjusting an insertion position proceeds, and thus the guide protrusions  234  is closely fixed to the inner circumference surface of the first shaft body  110 . 
       FIG. 4 b    shows another example of the first shaft part into which the nut part for adjusting an insertion position has been inserted in a cross-sectional view form. 
     As shown in  FIG. 4 b   , the first shaft body  110  of the first shaft part  100  may have guide grooves  112  corresponding to the guide protrusions  234  in the inner circumference surface thereof. The guide grooves  112  can prevent the idling of the nut part  230  for adjusting an insertion position attributable to the abrasion of the guide protrusions  234  upon screwing between the nut part  230  for adjusting an insertion position and the bolt part  220  for adjusting an insertion position. 
       FIG. 5  shows a mode for a driver practice in the portable cocking practice device according to an embodiment of the present invention in a perspective view form. 
     As shown in  FIG. 5 , when a user attempts cocking and uncocking practices upon swinging a driver, the user may set the portable cocking practice device in the mode for a driver practice by inserting the second shaft part  200  into the first shaft part  100  up to D, that is, a corresponding indication point of the insertion length indication part  212 , or withdrawing the second shaft part  200  from the first shaft part  100 . Furthermore, when the user attempts a change from the mode for a driver practice to a mode for an iron No. 6 practice, the user may set the portable cocking practice device in the mode for an iron No. 6 practice by further inserting the second shaft part  200  into the first shaft part  100  up to 6, that is, a corresponding indication point of the insertion length indication part  212 , in a specific length L. 
       FIG. 6  shows a portable mode in the portable cocking practice device according to an embodiment of the present invention in a perspective view form. 
     As shown in  FIG. 6 , the portable cocking practice device may be changed to the portable mode by fully inserting the second shaft part  200  into the first shaft part  100 . 
     As described above, the present invention enables a cocking practice for each golf club and also can improve user convenience and portability by allowing a user&#39;s to adjust a shaft length in accordance with golf clubs having various lengths from a driver to a sand wedge. 
     In an embodiment, the second shaft part  200  may further include a finishing member  240  which protects a user against a cutting plane formed on the opening part side of the first shaft part  100 . The finishing member  240  may be configured in the form of a hollow pipe having one end into which the first shaft part  100  is inserted and fixed and the other end through which the second shaft part  200  is moved and inserted into the first shaft part  100 . Furthermore, the other end of the finishing member  240  may be configured to indicate the insertion degree of the second shaft part  200  on the insertion length indication part  212  of the second shaft part  200 . 
     Next, the rod withdrawing part  300  is accommodated in the second shaft part  200 , so a specific rod is withdraw a given rod out of the second shaft part  200  by an uncocking operation of a golf swing. 
       FIG. 7A  shows an example of the rod withdrawing part in a cross-sectional view form. 
       FIG. 7B  shows the maximum withdraw state of the rod withdrawing part in a cross-sectional view form. 
     As shown in  FIGS. 7A and 7B , the rod withdrawing part  300  may include a withdrawing rod  310 , a head part  320  and an elastic member  330 . 
     The withdrawing rod  310  has one end accommodated in the second shaft part  200 , that is, the hollow within the second shaft body  210 , and the other end located outside the second shaft part  200 . In some embodiments, the other end of the withdrawing rod  210  may be configured to have a diameter greater than the internal diameter of the second shaft body  210 . 
     The head part  320  has a diameter greater than the internal diameter of the second shaft body  210  and is coupled to the other end of the withdrawing rod  310  outside the second shaft part  200 . In an embodiment, the head part  320  may be configured to have a plurality of air resistance faces  322 . The air resistance faces  322  can increase a golf swing exercise effect by increasing air resistance upon playing a golf swing. 
     The elastic member  330  is disposed in the hollow within the second shaft body  210 , and it restricts the one end of the withdrawing rod  310  by an elastic force and withdraws the withdrawing rod  310  to the outside of the second shaft part  200  by a length L 1  from A to A′ by an uncocking operation of a golf swing. In an embodiment, the elastic member  330  may be a coil type spring member  330  having one end clamped to the one end of the withdrawing rod  310  by specific clamping members  332  and  336  and the other end fixed to the inside of the second shaft body  210  by a specific fixing member  334 . For example, the rod withdrawing part  300  may be configured so that the one end of the withdrawing rod  310  is inserted into the center hole of the spring member  330 , a ring type member  332  for compressing the spring member  330  upon drawing the withdrawing rod  310  and a ferrule  334  for fixing the spring member  330  so that it does not deviate from the inside of the second shaft body  210  are inserted into the withdrawing rod  310  at the top and bottom of the spring member  330 , respectively, and a support pin  336  for supporting the ring type member  332  upon drawing the withdrawing rod  310  is inserted into the through hole  312  formed in the diameter direction at the one end of the withdrawing rod  310 . 
       FIG. 8  shows the state upon uncocking of the portable cocking practice device according to an exemplary embodiment of the present invention in a perspective view form. 
     As shown in  FIG. 8 , the portable cocking practice device according to the present invention withdraws the withdrawing rod  310  to which the head part  320  has been coupled when a user&#39;s performs an uncocking operation of a golf swing. Furthermore, when an accurate cocking and uncocking operation is performed, the spring member  330  is compressed to a maximum extent, so a maximum withdrawn state in which the withdrawing rod  310  is drawn to the maximum length L 1  is generated. When the maximum withdraw state is generated, the user&#39;s have a feeling of a specific impact and can check whether he or she has performed a correct cocking and uncocking operation oneself through such a feeling of an impact. 
     Meanwhile, as described above, in round of golf, 14 clubs having various lengths and weights from a driver to a sand wedge are used in average. The position of a ball placed ahead of a golfer upon addressing is different for each club. As a result, an impact point of time at which the head of each club comes into contact with a ball is different. Accordingly, the portable cocking practice device according to an exemplary embodiment of the present invention may further include a member  340  for adjusting an impact point of time. The member  340  for adjusting an impact point of time is disposed at the portion of the withdrawing rod  310  between the head part  320  coupled to the other end of the withdrawing rod  310  and the second shaft body  210 , and separate the head part  320  and the second shaft body  210  so that the withdrawing rod  310  coupled to the head part  320  is previously withdraw a given rod out of the second shaft body  210  in a specific length. As described above, when the initial withdraw length of the withdrawing rod  310  is changed by the member  340  for adjusting an impact point of time, the initial elastic force of the elastic member  330  that restricts the withdrawing rod  310  prior to a golf swing is changed. Accordingly, a point of time at which the withdrawing rod  310  reaches the maximum withdraw state during an uncocking operation, that is, an impact point of time at which, is also changed. 
       FIG. 9A  shows an example of the member for adjusting an impact point of time in a perspective view form. 
       FIG. 9B  shows the member for adjusting an impact point of time in  FIG. 9A  in a plan view form. 
     As shown in  FIGS. 9A and 9B , the member  340  for adjusting an impact point of time may include a through hole  342  and an insertion slot  344 . The member  340  for adjusting an impact point of time has a length corresponding to the initial withdraw length of the withdrawing rod  310  or the initial length of the spring member  330 , and may have a diameter supported by the second shaft body  210  and the head part  320 . That is, the external diameter of the member  340  may be configured to be greater than the internal diameter of the second shaft body  210 , and the internal diameter of the member  340  may be configured to be smaller than the external diameter of the second shaft body  210  and the external diameter of the head part  320 . In this case, the through hole  342  penetrates the member  340  in the length direction. Furthermore, the insertion slot  344  is formed in the diameter direction of the member  340  so that the withdrawing rod  310  is tightly fit into the insertion slot  344  and inserted into the through hole  342 . As described above, a user&#39;s can adjust an impact point of time upon playing a golf swing by adjusting the initial withdraw length of the withdrawing rod  310  prior to the golf swing using the members for adjusting an impact point of time which have various lengths. 
       FIG. 10  shows a method for adjusting an impact point of time in the portable cocking practice device according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 10 , the portable cocking practice device according to an exemplary embodiment of the present invention may be configured so that the member for adjusting an impact point of time is not mounted on the withdrawing rod  310  in the mode a for a driver practice. In this case, the initial length L a  of the spring member  330  accommodated in the second shaft body  210  becomes a maximum, and the longest time is taken for the withdrawing rod  310  to reach the maximum withdraw state upon uncocking operation. That is, an impact point of time is the slowest like an actual driver swing. For example, if a user&#39;s is a right-handed golfer, an impact in the mode for a driver practice is generated more on the left side than other modes. Meanwhile, in a mode b for an iron practice, a member  340   b  for adjusting an impact point of time which has a length for an iron practice may be mounted on the withdrawing rod  310 . In this case, the initial length L b  of the spring member  330  is reduced as short as the length of the member  340   b  for adjusting an impact point of time, and a point of time at which the maximum withdraw state of the withdrawing rod  310  is reached upon uncocking operation becomes faster than that in the mode for a driver practice. That is, an impact point of time becomes faster than that in the driver swing like an actual iron swing. Furthermore, in a mode c for a wedge practice, a member  340   c  for adjusting an impact point of time which has a length for a wedge practice may be mounted on the draw-out rod  310 . In this case, the initial length L c , of the spring member  330  is further reduced as short as the length of the member  340   c  for adjusting an impact point of time, and a point of time at which the withdrawing rod  310  reaches the maximum draw-out state upon uncocking operation becomes faster than that in the mode for an iron practice. That is, an impact point of time is the fastest like an actual wedge swing. For example, if a user is a right-handed golfer, an impact in the mode for a wedge practice is generated more on the right side than other modes. 
     In another exemplary embodiment, the member  340  for adjusting an impact point of time may include a plurality of members depending on a mode of the portable cocking practice device. Furthermore, the member  340  for adjusting an impact point of time may be configured to adjust the total weight of the portable cocking practice device by making different the weight of the member  340  for adjusting an impact point of time which is mounted in each mode as if each golf club actually has a different weight. 
       FIG. 11  is a diagram shows a method for adjusting an impact point of time of the portable cocking practice device according to another exemplary embodiment of the present invention. 
     As shown in  FIG. 11 , the portable cocking practice device according to another exemplary embodiment of the present invention may adjust the initial draw-out length of the withdrawing rod  310  or the initial length of the spring member  330  using the head part  320 . In this case, the withdrawing rod  310  may have screw threads  314  in at least part of the outer circumference surface thereof Furthermore, the head part  320  may have a through hole  324  screwed onto the screw threads  314  of the withdrawing rod  310 . That is, the head part  320  is screwed onto the withdrawing rod  310  through the through hole  324  and may previously draw the withdrawing rod  310  to the outside of the second shaft body  210  in a specific length depending on a screw coupling degree. 
     For example, in the mode a for a driver practice, a user&#39;s may withdraw the withdrawing rod  310  to the outside of the second shaft body  210  and also secure the initial length L a  of the spring member  330  for a driver practice by screwing the head part  320  onto the withdrawing rod  310  by turning the head part  320  a specific number of times. Furthermore, in the mode b for an iron practice, the user may further draw the withdrawing rod  310  to the outside of the second shaft body  210  and also adjust the initial length L a  of the spring member  330  to the initial length L b  for an iron practice by performing screw coupling with the withdrawing rod  310  by turning the head part  320  a specific number of times. Likewise, in the mode c for a wedge practice, the user may further draw the withdrawing rod  310  to the outside of the second shaft body  210  and also adjust the initial length L b  of the spring member  330  to the initial length L c  for a wedge practice by further performing screw coupling with the withdrawing rod  310  by turning the head part  320  a specific number of times. 
     As described above, in accordance with the present invention, a user&#39;s can have a feeling of an impact like an actual golf swing and also check whether the user takes a correct cocking and uncocking operation in person because the rod within the shaft coupled to a head is drawn out when the user takes the uncocking operation of a normal golf swing. In particular, cocking practices for each golf club are made possible and a user&#39;s convenience and portability can also be improved because the length and weight of the shaft can be adjusted in response to golf clubs having various lengths and weights from a driver to a sand wedge. Furthermore, a similarity with an actual golf swing in which an impact point of time is different for each golf club can be increased and a cocking practice effect can be improved because an impact point of time at which the rod within the shaft is drawn out as much as possible can be adjusted. Furthermore, various embodiments according to the present invention may achieve several other technical objects in addition to the contents described in this specification in related technical fields in addition to a corresponding technical field. 
     The detailed embodiments of the present invention have been described so far. However, those skilled in the art will evidently understand that various modification embodiments may be implemented without departing from the technical range of the present invention. Accordingly, the aforementioned disclosed embodiments should be considered from a descriptive viewpoint not a limit viewpoint. That is, the range of true technical spirit of the present invention appears in the claims and all of differences within an equivalent range thereof should be construed as being included in the present invention.