hereinafter , the training device for golf swing according to the present invention will be described in detail with reference to the attached drawings illustrating examples of the present invention . fig1 a and fig1 b are perspective views showing a training device for golf swing according to a first example of the present invention . referring to fig1 a , the training device for golf swing according to the first example of the present invention comprises a first body section ( 10 a ) having a rod shape . a grip section ( 15 ) is fitted on one end part of the first body section and one end part of a rod section ( 11 ) is screw - joined to the other end part of the first body section ( 10 a ). the rod section ( 11 ) has a larger outer diameter than that of the first body section ( 10 a ) and an inner space , and an insertion hole ( 19 ) is formed at the other end part of the rod section ( refer to fig2 a ). a part of a second body section ( 10 b ) is inserted into the insertion hole ( 19 ) formed at the other end part of such a rod section ( 11 ), wherein formed at one end part inserted is a protrusion ( 17 ) having a larger outer diameter than the diameter of the insertion hole ( 19 ). furthermore , a head section ( 14 ) is installed at the other end part of the second body section ( 10 b ). in this connection , a neck ( 16 ) of the head section ( 14 ) is screw - joined to the second body section ( 10 b ), whereby the head section can be replaced with drivers , irons , various weights etc . accordingly , the user can plan strength suitable for himself or herself and phased enhancement of swing power . furthermore , an elastic member ( 18 ) is arranged around the second body section ( 10 b ) in such a way that both end parts of the member contact with the protrusion ( 17 ) and inner surface of the other end part of the rod section ( 11 ). therefore , the elastic member ( 18 ) generates elastic resistance according to swing speed in swing motion such that a part of the second body section ( 10 b ) can be moved within the rod section ( 11 ) by centrifugal force . in this connection , the elastic member ( 18 ) is in a coil spring shape and formed in such a way that its pitch gradually narrows from one end part contacting with the protrusion ( 17 ) to the other end part contacting with the inner surface of the other end part of the rod section ( 11 ). in the rod section ( 11 ) of the training device for golf swing according to such first example , a plurality of fixing holes ( 12 ) are formed in a row in a longitudinal direction of the second body section ( 10 b ), and a length - adjusting means ( 13 ) is provided which engages any one selected from the plurality of fixing holes ( 12 ). preferably , the length - adjusting means ( 13 ) may be a bolt engaging the fixing holes ( 12 ). the length - adjusting means ( 13 ), which engages the holes to be inserted into the rod section ( 11 ) as described above , adjusts a range of movement of the elastic member ( 18 ) by controlling the position of the protrusion ( 17 ). furthermore , the rod section ( 11 ) is comprised of a case ( 11 a ) and a cap ( 11 b ), which allows change of the elastic member ( 18 ), whereby the user can plan strength suitable for himself or herself and phased enhancement of swing power . the training device for golf swing of fig1 b comprises shorter grip section ( 15 ) and shorter first body section ( 10 a ) than those in fig1 a such that the device may be used in a narrow space , for example indoors . since the first body section ( 10 a ) is screw - joined to one end part of the rod section ( 11 ), change can be allowed to the grip section ( 15 ) and the first body section ( 10 a ) each having a length for use in a specific place . that is , for the training device for golf swing of fig1 b , by replacing the body section ( 10 a ) with shorter one , swing can be exercised in a narrow room as well as outdoors . furthermore , the neck ( 16 ) of the head section ( 14 ) is also screw - joined to the second body section ( 10 b ), whereby the head section ( 14 ) can be changed to various weights , drivers , irons , putters and the like . accordingly , the head section ( 14 ) of the training device for golf swing for use in a narrow place may be changed to iron and conveniently used . fig2 a is a sectional view taken along line a - a ′ of fig1 before swing , and fig2 b is a sectional view taken along line a - a ′ of fig1 after swing . when a user takes up the swing posture holding the grip section ( 15 ) of training device for golf swing according to the first example of the present invention , the protrusion ( 17 ) at one end part of the second body section ( 10 b ) is in a position controlled by the length - adjusting means ( 13 ) within the rod section ( 11 ), as shown in fig2 a . if swing is done , the elastic member ( 18 ) is pressed toward the inner surface of the other end part of the rod section ( 11 ) by the centrifugal force generated in swing as shown in fig2 b . at this time , the protrusion ( 17 ) at one end part of the second body section ( 10 b ) fully presses the elastic member ( 18 ) toward the other end part of the rod section ( 11 ), and the second body section ( 10 b ) is extended out from the rod section ( 11 ) while the protrusion ( 17 ) engages the inside of the rod section ( 11 ). that is , by overcoming the elastic resistance from the elastic member ( 18 ) and accelerating the head speed , the second body section ( 10 b ) is extended out from the rod section ( 11 ), and thus the length of the training device for golf swing is increased . in this connection , the magnitude of maximum elastic resistance from the elastic member ( 18 ) may be varied by adjusting of the range of movement of the elastic member ( 18 ) by means of the length - adjusting means ( 13 ) and the fixing holes ( 12 ). that is , since the higher the swing speed is , the larger the centrifugal force is and accordingly the larger the magnitude of the elastic resistance that can be overcome is , the user can acquaint him or herself with swing feeling by properly adjusting a strength according to swing . the elastic member ( 18 ) used in the training device for golf swing of the first example is in a coil spring shape and formed in such a way that its pitch gradually narrows from one end part contacting with the protrusion ( 17 ) to the other end part contacting with the inner surface of the other end part of the rod section ( 11 ). accordingly , the elastic resistance can be adjusted stepwise according to the high or low swing speed , and the highest swing speed can be obtained at the moment of impact . muscles for golf swing can be strengthened by increasing the centrifugal force while making the impact strong and fast by accelerating the head speed through overcoming of the elastic resistance produced from the coil spring in swing . in addition , the training for increasing a flying distance of the golf ball and power can be easily carried out . if the centrifugal force is decreased after swing , the second body section ( 10 b ) is returned to its initial position by the elastic force of the elastic member ( 18 ). accordingly , the time of maximization of the hitting power can be easily recognized visually through the change of the length of the training device for golf swing . when swing is done using the training device for golf swing according to the first example of the present invention as described above , the centrifugal force can be maximally exhibited at the time of rotation of the head section ( 14 ) by swing in a stable and natural posture with the shoulders and arms of the user being relaxed . furthermore , a training can be easily carried out repeatedly for producing centripetal force corresponding to the centrifugal force produced at the time of rotation of head section ( 14 ) through the body of the user . that is , more stable and exact swing motion is made possible such that the centrifugal force according to rotation of the training device for golf swing and the centripetal force corresponding to the centrifugal force are balanced . fig3 is a perspective view showing a training device for golf swing according to a second example of the present invention . referring to fig3 , in the training device for golf swing according to the second example of the present invention , a head section ( 24 ) is installed at one end part of a first body section ( 21 b ) of a rod shape , and a neck ( 28 ) of the head section ( 24 ) is screw - joined to the first body section ( 21 b ) such that the head section can be changed . furthermore , the other end part of the first body section ( 21 b ) is integrally connected with one end part of a rod section ( 21 a ) having an inner space and a larger outer diameter than that of the first body section ( 21 b ). an insertion hole ( 29 ) is formed at the other end part of the rod section ( 21 a ), and inserted into this insertion hole ( 29 ) is a part of a second body section ( 20 ), and one end part of the second body section inserted is formed with a protrusion ( 26 ) having a larger outer diameter than the diameter of the insertion hole ( 29 ). furthermore , a grip section ( 25 ) is fitted at the other end part of the second body section ( 20 ). furthermore , an elastic member ( 27 , refer to fig4 a ) is arranged around the second body section ( 20 ) in such a way that both end parts of the member contact with the protrusion ( 26 , refer to fig4 a ) and inner surface of the other end part of the rod section ( 21 a ). the elastic member generates the elastic resistance according to swing speed in swing motion such that a part of the second body section ( 20 ) can be moved within the rod section ( 21 a ) by the centrifugal force . in this connection , the elastic member ( 27 ) is in a coil spring shape and formed in such a way that its pitch gradually narrows from one end part contacting with the protrusion ( 26 ) to the other end part contacting with the inner surface of the other end part of the rod section ( 21 a ). a plurality of recesses ( 22 ) are formed with a fixed interval on outer surface of the part of the second body section ( 20 ) inserted within the rod section ( 21 a ) of the training device for golf swing according to the second example . outside the other end part of the rod section ( 21 a ), a length - adjusting means ( 23 ) is fitted in any one selected from the plurality of the recesses ( 22 ), thereby controlling position of the protrusion ( 26 ) within the rod section ( 21 a ) to adjust the range of movement of the elastic member ( 27 ). fig4 a is a sectional view taken along line b - b ′ of fig3 before swing , and fig4 b is a sectional view taken along line b - b ′ of fig3 after swing . referring to fig4 a and fig4 b , when the user takes up the swing posture holding the grip section ( 25 ) of the training device for golf swing according to the second example of the present invention , the protrusion ( 26 ) at one end part of the second body section ( 20 ) is in the position controlled by the recess ( 22 ) and the length - adjusting means ( 23 ) within the rod section ( 21 a ), as shown in fig4 a . at this time , if swing is done , the elastic member ( 27 ) is pressed toward the inner surface of the other end part of the rod section ( 21 a ) by the centrifugal force generated in swing , as shown in fig4 b . at this time , the protrusion ( 26 ) at one end part of the second body section ( 20 ) fully presses the elastic member ( 27 ) toward the other end part of the rod section ( 21 a ), and the second body section ( 20 ) is extended out from the rod section ( 21 a ) while the protrusion ( 26 ) engages the inside of the rod section ( 21 a ). that is , by overcoming the elastic resistance from the elastic member ( 27 ) and accelerating the head speed , the second body section ( 20 ) is extended out from the rod section ( 21 a ), and thus the length of the training device for golf swing is increased . in this connection , the magnitude of maximum elastic resistance from the elastic member ( 27 ) may be varied by adjusting of the range of movement of the elastic member ( 27 ) by fitting of the length - adjusting means ( 23 ) in the recesses ( 22 ) formed on the outer surface of the second body section ( 20 ). that is , since the higher the swing speed is , the larger the centrifugal force is and accordingly the larger the magnitude of the elastic resistance that can be overcome is , the user can acquaint him or herself with swing feeling by properly adjusting the strength according to swing . if the centrifugal force is decreased after swing , the second body section ( 20 ) is returned to its initial position by the elastic force of the elastic member ( 27 ). accordingly , the time of maximization of the hitting power can be easily recognized visually through the change of the length of the training device for golf swing . the elastic member ( 27 ) used in the training device for golf swing of the second example is in a coil spring shape and formed in such a way that its pitch gradually narrows from one end part contacting with the protrusion ( 26 ) to the other end part contacting with the inner surface of the other end part of the rod section ( 21 a ), as in the first example . accordingly , elastic resistance can be adjusted stepwise according to the high or low swing speed , and the highest swing speed can be obtained at the moment of impact . fig5 is a perspective view showing a training device for golf swing according to a third example of the present invention . referring to fig5 , in the training device for golf swing according to the third example of the present invention , an insertion groove ( 35 , refer to fig6 a ) is formed at one end part of a first body section ( 30 a ) of a rod shape , and a grip section ( 31 ) is fitted at the other end part of the first body section ( 30 a ). furthermore , a part of a second body section ( 30 b ) is inserted into the insertion groove ( 35 ) of the first body section ( 30 a ), wherein formed at one end part of the second body section ( 30 b ) inserted is a protrusion ( 34 ) having a larger outer diameter than the inner diameter of the insertion groove ( 35 ), and a head section ( 32 ) is installed at the other end part of the second body section ( 30 b ). a neck ( 33 ) of the head section ( 32 ) is screw - joined to the second body section ( 30 b ) such that the head section can be changed . furthermore , an elastic member ( 36 , refer to fig6 a ) is arranged between the first body section ( 30 a ) and the second body section ( 30 b ) such that one end part of the member contacts with the protrusion ( 34 ) and the other end part is secured on inner surface of one end part of the first body section ( 30 a ). such an elastic member ( 36 ) generates elastic resistance according to swing speed in swing motion such that a part of the second body section ( 30 b ) can be moved within the insertion groove ( 35 ) by the centrifugal force . in this connection , the elastic member ( 36 ) is in a coil spring shape and formed in such a way that its pitch gradually narrows from one end part contacting with the protrusion ( 34 ) to the other end part contacting with the inner surface of one end part of the first body section ( 30 a ). accordingly , the elastic resistance can be adjusted stepwise according to the high or low swing speed . fig6 a is a sectional view taken along line c - c ′ of fig6 before swing , and fig6 b is a sectional view taken along line c - c ′ of fig6 after swing . referring to fig6 a and fig6 b , when the user takes up the swing posture holding the grip section ( 31 ) of training device for golf swing according to the third example of the present invention , the protrusion ( 34 ) at one end part of the second body section ( 30 b ) and a part of the second body section ( 30 b ) are inserted within the insertion groove ( 35 ), as shown in fig6 a . at this time , if swing is done , the elastic member ( 36 ) is pressed while the protrusion ( 34 ) is moving toward the inner surface of one end part of the first body section ( 30 a ) by the centrifugal force generated in swing , as shown in fig6 b . accordingly , the second body section ( 30 b ) is pushed out through the insertion groove ( 35 ) toward the side of the head section ( 32 ) by the generated centrifugal force . therefore , if the training device for golf swing according to the third example of the present invention is used , the head speed can be accelerated through overcoming of the elastic resistance produced from the coil spring in golf swing . accordingly , by increasing the centrifugal force while making the impact strong and fast , muscles for golf swing can be strengthened and the training for increasing a flying distance of the golf ball and power can be easily carried out . fig7 a is a sectional view before swing of the training device for golf swing according to a fourth example of the present invention , and fig7 b is a sectional view after swing of the training device for golf swing according to the fourth example of the present invention . referring to fig7 a and fig7 b , since a grip section ( 41 ), a first body section ( 40 a ) and a second body section ( 40 b ) illustrated are the same as those of the third example of the present invention , description of detailed construction and operations thereof will be omitted . of course , the grip section ( 41 ), the first body section ( 40 a ) and the second body section ( 40 b ) illustrated may be formed according to the first and second examples . in the fourth example of the present invention , the head section consists of a supporting part ( 47 ) connected with the other end part of the second body section ( 40 b ) and a weight - adjusting weight ( 48 ) coupled with the supporting part ( 47 ). in this connection , formed in a central part of lower surface of the supporting part ( 47 ) is a groove ( 47 a ) into which a protrusion ( 48 a ) of the weight - adjusting weight ( 48 ) can be inserted . the protrusion ( 48 a ) of the weight - adjusting weight ( 48 ) is in a bolt shape and is formed with threads on its outer surface , and inner surface of the groove ( 47 a ) of the supporting part ( 47 ) is formed in a nut shape so as to engage the threads of the protrusion ( 48 a ). in this connection , the supporting part ( 47 ) and the weight - adjusting weight ( 48 ) may be coupled with each other in another various ways other than thread engagement . furthermore , it goes without saying that the protrusion ( 48 a ) may be formed in a nut shape and the supporting part ( 47 a ) may be formed in a bolt shape . as described above , the weight - adjusting weight ( 48 ) coupled with the supporting part ( 47 ) can be easily assembled and disassembled , whereby the weight - adjusting weight ( 48 ) can be changed to one having a weight suitable for the user in use of the training device for golf swing . fig8 is a sectional view showing the weight - adjusting weight according to the fourth example . referring to fig8 , the weight - adjusting weights ( 48 - 1 , 48 - 2 , 48 - 3 , 48 - 4 ) are provided in various sizes , and its weight varies depending on its size , wherein the larger the size of the weight - adjusting weight ( 48 - 1 , 48 - 2 , 48 - 3 , 48 - 4 ) is , the heavier the weight is . that is , if the weight - adjusting weight of the smallest size is “ 48 - 1 ” and the weight - adjusting weight of the largest size is “ 48 - 4 ”, and the weight - adjusting weights having a size between the smallest and largest sizes are “ 48 - 2 ” and “ 48 - 3 ” in the order of size , the order of weight is “ 48 - 1 ”& lt ;“ 48 - 2 ”& lt ;“ 48 - 3 ”& lt ;“ 48 - 4 ”. in this connection , the sizes of the protrusions ( 48 a - 1 , 48 a - 2 , 48 a - 3 , 48 a - 4 ) coupled with the groove ( 47 a , refer to fig7 ) of the supporting part ( 47 , refer to fig7 ) are all the same . furthermore , although the weight - adjusting weight ( 48 - 1 , 48 - 2 , 48 - 3 , 48 - 4 ) may be heavier as its size increases , if the material for each weight - adjusting weight ( 48 - 1 , 48 - 2 , 48 - 3 , 48 - 4 ) is different from each other , its specific weight is also different from each other , so the weight - adjusting weight ( 48 - 1 , 48 - 2 , 48 - 3 , 48 - 4 ) may be made using different material . although the technical concepts of the present invention have been concretely described according to the preferred examples as described above , it should be understood that the examples are given only for the purpose of illustration of the technical concepts , not limitation thereof . furthermore , persons having ordinary skills in the art will understand that various modified examples can be made without departing from the technical concepts of the present invention .
the present invention relates to a training device for golf swings , which overcomes the elastic resistance arising from the coil - spring on a golf swing and accelerates the head speed to strengthen and to accelerate the impact , thus magnifying the centrifugal force . the training device for golf swings according to the present invention includes : a first body section having a rod - shape ; a grip section equipped on one side of the above first body section ; a rod section which has one end thereof screw joined to the other side of the first body section , a larger outer - diameter than that of the first body section , and an inner space ; a second body section wherein a part thereof is inserted into the insertion hole formed in the other side of the above rod section , and a protrusion having a larger outer diameter than that of the above insertion hole is formed in one side of the inserted part ; a head section installed in the other side of the above second body section ; and an elastic member positioned around the second body to come in contact with both ends at the protrusion and the inner space of the other side of the rod , and thus by the centrifugal force , causing elastic resistance letting the other side of the second body be movable in the inner space of the rod according to the swing speed when the user performs the swing . with this constitution , the present invention enables easy training to increase the flying distance of a golf ball and power as well as strengthening muscles for golf swings .