JP2019115474A - Putter club - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a putter club equipped with a shaft made of FRP having excellent sense of distance, directionality and shot feeling. SOLUTION: The putter club according to the present invention has a shaft made of fiber reinforced resin mounted on a head, and the ratio of torsional rigidity to bending rigidity (GIp / EI) of the shaft is on the grip side from the head mounting position. It is formed so that the displacement width of the torsional rigidity to the bending rigidity ratio (GIp / EI) is 0.5 or less over the entire length, which is substantially uniform from the intermediate region to the grip region. It is characterized by being. [Selection diagram] Fig. 3

Description

  The present invention relates to a putter club carried when playing golf, and in particular to a putter club having a shaft formed of fiber reinforced resin (FRP).

  Conventionally, a putter club used for putting on golf requires a delicate touch, and its shaft is mainly made of steel. On the other hand, many ordinary wood type clubs and iron type clubs use a shaft made of fiber reinforced resin (FRP), and a golf club having an FRP shaft has a steel shaft. The weight of the FRP shaft can be reduced more than that of the object, so that the swing speed can be improved, and the FRP shaft can be easily bent.

  By the way, when assembling a golf club, there is a demand to make the appearance of all golf club shafts uniform. Recently, as with FRP shafts of wood-type clubs and iron-type clubs, shafts made of FRP in putter clubs are also required. The ones wearing the are coming out. Conventionally, in the case of mounting a shaft made of FRP in a putter club, the arrangement mode of the prepreg sheet constituting the same is the same as the shaft made of FRP mounted on a wood type club or an iron type club. For example, as described in Patent Document 1, it is described that an FRP shaft of a putter club is applied to a wood type club or an iron type club.

Unexamined-Japanese-Patent No. 2015-231426

  By the way, the putter club is for rolling the ball with a certain sense on the green, and it is completely different from the hitting form of the wood type club and the iron type club swinging a large swing, and a delicate touch Required Therefore, when using an FRP shaft in a putter club, it should be created with a completely different design concept from a wood type club or an iron type club, but a conventional putter club is disclosed in Patent Document 1 Thus, the idea is that the configuration of the FRP shaft of a wood type club or an iron type club can be applied, and sufficient consideration has not been made.

  For example, shafts of wood-type clubs and iron-type clubs need to take into consideration the flexural rigidity characteristics that give a certain degree of deflection when swinging, while shafts of putter clubs hit with a large swing. Instead of using a pendulum-like swing to hit the ball to give distance and directionality, it has a slight sense of distance with a low flexural rigidity like a shaft of a wood-type club or iron-type club. It is considered inappropriate for putting out. In addition, the impact at the time of hitting causes twist around the fixed part of the shaft, but considering the impact acting on the head at the time of hitting and swing trajectory etc., the shaft and putter of wood type club or iron type club regarding torsional rigidity. The shaft of the club needs to be configured differently.

  In this respect, steel shafts are often used for putter clubs because steel has an isotropic property, so the ratio of torsional rigidity to bending rigidity (GIp / EI) is in the longitudinal direction. This is considered to be the reason that it becomes substantially uniform over the entire length, which leads to stabilization of rigidity against bending and twisting, resulting in better distance and directionality. Therefore, when constructing a shaft for putter club with FRP, it seems to be better to have a steel shaft-like property, but it further improves the overall balance including the sense of distance, directionality, and feel at impact. There is room for improvement in order to

  The present invention was made focusing on the above-mentioned problems, and an object of the present invention is to provide a putter club equipped with an FRP shaft excellent in sense of distance, directionality and hitting feel.

  In order to achieve the above object, the putter club according to the present invention has a structure in which a shaft made of fiber reinforced resin is attached to a head, wherein the shaft has a ratio of torsional rigidity to bending rigidity (GIp / EI) It decreases from the mounting position to the middle area on the grip side, is substantially uniform from the middle area to the grip area, and the displacement width of the ratio (GIp / EI) of the torsional rigidity to the bending rigidity is 0.5 or less over the entire length. It is characterized in that it is formed as follows.

  The shaft of the putter club described above is formed so that the displacement width of the ratio (GIp / EI) of the torsional rigidity and the bending rigidity is 0.5 or less over the entire length and substantially uniform from the intermediate region to the grip region Therefore, like the steel shaft, the sense of rigidity against bending and twisting is uniformed along the length direction, and the ball feels the same sense of distance and direction as expected when swinging in a pendulum shape to hit the head against the ball. It becomes easy to convey. Further, in the present invention, the ratio (GIp / EI) of the torsional rigidity and the bending rigidity is reduced from the head mounting position to the middle region on the grip side (in other words, the bending rigidity of the grip region is increased from the middle region of the shaft) Therefore, the bending of the shaft before hitting is reduced and the behavior of the head, in particular the vertical direction, is stabilized, and the swing of the shaft after hitting is also stabilized, and the sense of distance as expected by the player and It makes it easier to convey a sense of direction to the ball.

  If the rigidity of the area to which the head is attached is increased, the flexibility in the head area is reduced compared to the steel shaft, and the shot feeling becomes hard. It is preferable that the griped hand feel is easily transmitted to the head side so as not to lower the feel at impact, specifically, a position about 200 mm from the tip of the shaft.

  According to the present invention, it is possible to obtain a putter club equipped with an FRP shaft excellent in feeling of distance, directionality and feel at impact.

The front view which shows an example of the putter club which concerns on this invention. It is a figure which shows the characteristic along an axial length direction about the shaft made from FRP which concerns on this invention, and the shaft made from steel, and the shaft for comparison FRP, (a) is a graph which shows bending rigidity distribution, (b) is. The graph which shows torsional rigidity distribution. The graph which shows the characteristic of (GIp / EI) along the longitudinal direction about each shaft shown in FIG. The figure which shows the position of the ball which hits a head in swinging the pendulum by a robot testing machine. BRIEF DESCRIPTION OF THE DRAWINGS The pattern figure which showed one structural example of the prepreg sheet which comprises the shaft made from FRP used for the putter club which concerns on this invention, and a prepreg sheet for reinforcement.

Hereinafter, embodiments of a putter club according to the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing an example of a putter club according to the present invention.

The putter club 1 shown in FIG. 1 includes a shaft 10 made of fiber reinforced resin (made of FRP) formed as described later, and a head (putter head) 20 is mounted on the tip end side thereof, and a base end On the side, a grip 30 formed of rubber or the like is mounted.
The head 20 has a main body 21 provided with a face surface 21a on which a ball is hit, and a protrusion 21b protruding upward is integrally formed on one end side of the upper surface of the main body 21. A hosel 21c having a circular fitting hole is integrally formed at the projecting end of the projecting portion 21b, and the tip of the shaft 10 is inserted and fixed in this portion. Although the fixing range between the shaft 10 and the fitting hole of the hosel 21c depends on the configuration of the head, it is about 20 mm in the present embodiment.

  The shaft 10 is formed by winding a plurality of prepreg sheets, in which reinforcing fibers are impregnated with a synthetic resin, around a core metal, as described above, and thermally curing the core to decore the core. The prepreg sheet constituting the shaft is wound on a prepreg sheet (main body layer) for the main body wound around its entire length and a partial sheet wound in a part in the longitudinal direction, for example, the tip region of the shaft 10 There is a reinforced prepreg sheet (reinforcement layer) to be turned. In addition, the structure of the prepreg sheet wound around a core metal, the prepreg sheet for reinforcement, and its arrangement example are mentioned later.

  The prepreg sheet has reinforcing fibers oriented in the axial direction (hereinafter, also referred to as an axial direction sheet) so that the body layer of the shaft constituting the FRP improves the bending rigidity and the torsional rigidity, and Reinforcing fibers are oriented in an inclined and cross direction in the axial direction (A fiber in which the reinforcing fibers are oriented at ± 45 ° with respect to the axial direction so as to improve the torsional rigidity in a balanced manner is preferred, and the cross direction) Is also used as a sheet). In this case, as the characteristics of the shaft, it is possible to construct a shaft of two characteristics by the configuration of the prepreg sheet to be the body layer on the outer layer side. That is, when the axial direction sheet is wound around the outer layer, the shaft becomes hard (high rigidity) and easily twisted. When the cross direction sheet is wound around the outer layer, the shaft becomes soft (low rigidity) and difficult to twist. Become.

  Fig.2 (a) is a graph which shows the bending rigidity characteristic (EI characteristic) which made the length of a shaft a horizontal axis, and made the bending rigidity a vertical axis, and FIG.2 (b) has a length of a shaft a horizontal axis. It is a graph which shows the torsional rigidity characteristic (GIp) which made the vertical axis the torsional rigidity. In these graphs, a shaft according to an embodiment embodying the configuration of the present invention (a), a first comparative example (a) which is a shaft made of FRP, and a steel shaft (c) are displayed. There is. Moreover, the graph shown in FIG. 3 shows the characteristic of GIp / EI about the shaft shown to FIG. 2 (a) (b).

Here, the bending stiffness (EI) and the torsional stiffness (GIp) described above are derived by the following calculation method.
With regard to flexural rigidity, Young's modulus (longitudinal elastic modulus) E can be specified by calculation from the specifications of the configuration (material) of the prepreg sheet constituting the shaft and the arrangement mode (laminated structure), I (cross-section For the second moment),
^{_{I = π (D 2 4 -D}} 1 4) / 64 can be derived by (Equation 1).

With regard to the torsional rigidity (GIp), the shear modulus (transverse modulus) G is calculated from the specifications of the configuration (material) of the prepreg sheet constituting the shaft and the arrangement mode (laminated structure) as described above. For Ip (section torsional moment),
^{_{Ip = π (D 2 4 -D}} 1 4) / 32 can be derived by (Equation 2).
In the above (Formula 1) and (Equation 2), D ₂ is the outer diameter of the shaft, D ₁ is the inside diameter of the shaft.
Further, since the FRP shaft is configured by winding a plurality of materials, the numerical value of the entire shaft can be calculated by adding the calculated values of each layer.

For bending stiffness (EI) of FRP shaft that is actually formed, the shaft is horizontal and two points away from the measurement point are supported, and the force from above is applied to the position of the central measurement point (P It can be derived by measuring the amount of deflection (δ) when adding. In particular,
^{EI = (L 3/48)} × (P / δ)
It is possible to derive from the formula of
The maximum load P is 20 kgf, and the distance L between supports is 200 mm.
By the above method, it is possible to obtain the EI of the center position measurement point between two points of support, and by shifting the support position, numerical values (numerical values for each position of the shaft across the longitudinal direction; for example, 50 mm) It becomes possible to calculate the interval numerical value).

In addition, with regard to the torsional rigidity (GIp) of the FRP shaft that is actually formed, the shaft was made horizontal and one end was fixed, held at a position separated by L mm from the fixed portion, and torque Tr was applied to the holding portion It can be derived by measuring the torsion angle A (radian) of the shaft. In particular,
GIp = L × Tr / A
It is possible to derive from the formula of
The torque Tr is 139 (kgf · mm), and the fixed holding distance L of the shaft is 200 mm.
By the above method, it is possible to obtain the GIp of the central position between the shaft fixing and holding, and by shifting the position, numerical values (numerical values for each shaft position across the longitudinal direction; for example, numerical values at intervals of 50 mm) ) Can be calculated.

  As for the steel shaft, as described above, the ratio of GIp / EI is uniformed over the entire length of the shaft because it is isotropic. It changes a little. If iron is considered to be the main component of the shaft, the Poisson's ratio is about 0.3, so it is considered to be about 0.87 from the relationship of E = 2 (1 + ν). For this reason, in an actual steel shaft, although depending on the constituent material, it is considered to be within the range of 0.85 ± 0.1 (in FIG. 3, it is 0.85).

As shown in FIG. 2 and FIG. 3, since the steel shaft (c) has isotropy, the distribution of bending stiffness and torsional rigidity becomes substantially the same over the entire length of the shaft, and bending stiffness and torsional rigidity are obtained. The ratio of (Gip / EI) is substantially uniform (substantially linear over the entire length of the shaft, and the displacement width is substantially zero). Although it is heavier than FRP shaft, it is thought that a shaft that easily conveys the sense of the player's image in terms of distance and direction to the head can be obtained because there is no deviation between bending and torsional rigidity. .
The object of the present invention is to provide an FRP shaft for a putter club which has an improved sense of distance and direction and further a feel at impact while having the advantages of such a steel shaft. The distribution of flexural rigidity and torsional rigidity is configured to have the following characteristics.

  It should be noted that since the FRP shaft is influenced by the direction of the reinforcing fiber of the prepreg sheet to be wound and has an anisotropic characteristic, when it is desired to make it a characteristic like a steel shaft, bending rigidity and torsion are required. The stiffness properties need to be configured to vary substantially the same over the longitudinal direction.

  The shaft of the present embodiment, as shown in (a) of FIG. 2 (b), is configured so as to have substantially the same characteristics as the steel shaft (c) in terms of torsional rigidity, As shown in (a) of 2 (a), it is configured to be higher than the steel shaft (c) from the middle area to the grip area (area indicated by R). That is, as shown in FIG. 3, since the bending rigidity is set to be higher while the similar distribution curve is made from the intermediate region to the grip region (region indicated by R) as compared with the steel shaft, as shown in FIG. The ratio of rigidity to bending rigidity (GIp / EI) decreases from the head mounting position to the middle area on the grip side, and is substantially uniform from the middle area to the grip area (area indicated by R). In this case, the displacement width of the ratio of torsional rigidity to flexural rigidity (GIp / EI) is formed to be 0.5 or less over the entire length, and the ratio of flexural rigidity to torsional rigidity (GIp / EI) In order to prevent the displacement width of the shaft from increasing, the feeling does not largely deviate from the steel shaft.

  The shaft made of FRP of the comparative example (A) shown in FIG. 2 is obtained by reversing the disposition of the main body layer of the shaft of this embodiment, and the sheet in the cross direction is wound on the outer layer side and the axial length is on the inner layer side The directional sheet is wound into a shaft which is difficult to twist as a whole and is easy to bend. In such a shaft, as shown in FIG. 3, the characteristic of GIp / EI rises sharply in the shaft tip region.

  Since putting with a putter club strikes with a pendulum swing, the feel at the hand side is particularly important, but unlike a iron club or a wood club, there is no large impact on the head, so it is torsionally rigid. It is thought that improving bending stiffness is a factor to be considered rather than improvement. The shaft (a) of the present embodiment is made to be hard and not move (a feeling such as this can be obtained even when it is actually swung) by increasing the bending rigidity on the grip side from the intermediate region, The behavior of the head during the swinging of the pendulum, in particular, the vertical trajectory, is stabilized to facilitate center hitting (make it easier for the player to hit the center).

  That is, since the bending of the shaft before hitting is reduced, the variation in the vertical movement is suppressed, and it becomes easy to hit at a stable position. In addition, even if the ball is slightly displaced from the center and the ball is hit, the rigidity of the hand is increased, so that when the ball is hit, the shaft is prevented from returning due to the repulsion of the ball, thereby suppressing variation in distance. (Even if you hit the ball with the center off, there is not much variation in distance as when you hit the center).

In fact, when the same head (the head shown in FIG. 1) was attached to the shaft having the above-mentioned characteristics and a trial hit test was conducted, the following results were obtained.
In the test hitting test, using a robot testing machine, change the hitting position with the same pendulum width and hit four balls at a time so that the head hits the ball with the same impact force, and verify the variation in distance and variation in direction. I did. That is, when the player puts the ball, he swings the putter club like a pendulum and strikes the ball, but usually the head has a mark for grasping the center position and the player does not have high putting swing speed. , It can be grasped whether or not you hit at the center position. However, even if it is thought that the ball is hit at the center position, when hit on the upper side of the face surface and when hit on the lower side, it can not be easily determined just from above.

As described above, in the case where the hit point deviation occurs in the vertical direction, if the distance and the directionality are different between when the ball is hit at the center and when the ball is hit at the center position, the player is uneven even though the ball is hit at the center position. May feel that Therefore, in the following robot test, in consideration of this point, the steel shafts of FRP shafts (a) and (b) and (c) shown in FIGS. When the ball was hit, it was verified how much variation occurred.
The results are shown in the following table.

In the above evaluation results, the center of the hit point means that the height H from the ground P of FIG. 4 to the lower edge of the putter head 21 is set to 6 mm. The center hit point is a hit at the center C of the face surface 21a with respect to the ball 100, and is an ideal hit point position when the player actually puts. Further, 5 mm below the center of the hit point means one in which the height H from the ground P to the lower edge of the putter head 21 is set to 11 mm in FIG. Therefore, this hit point position is hit far below the center C of the face surface 21a. Moreover, 5 mm above the center of a hit point means what set height H from the ground P to the lower edge of the putter head 21 in FIG. 4 to 1 mm. Therefore, the hit position is hit far above the center C of the face surface 21a.

  In Table 1, the distance is the distance (mm) to the point where the ball stopped when putting on the same pendulum swing. In the horizontal direction, a line extending vertically from the face surface is taken as the center line, and the distance deviated from that line is indicated by (+) that deviates to the right and (-) that deviates to the left. ing. In this case, the three shafts (A), (B), and (C) are mounted on the head of the same structure, and the weight balance as a putter club causes differences in distance and directionality (the putter club edge) However, it is important to note that since the player is always aware of hitting at the center, there is no variation in distance or direction when hitting at center C, and when viewed from above, center C (see It is preferable that there is not much difference (does not greatly vary) between hitting the ball at the center (when the ball is hit at the center C) (it is actually hitting at an off position).

For this reason, what is evaluated by the robot test is the standard deviation (variation) when hitting at the proper position (center hitting point), and the amount of deviation from that when hitting at the proper position when hitting at the shifted position. And the standard deviation (variation) including the center hit.
In the trial hit test, four balls were run at different hit positions.

(Measurement result of distance)
As a result of centering, the standard deviation is 21.21 for the FRP shaft (a) of the present embodiment, while the comparative FRP shaft (a) is 28.61, the steel shaft (c) is As a result, the variation in the distance at the time of center hitting was the smallest in this embodiment.
As a result of 5 mm under the center, the FRP shaft (a) of this embodiment has an average value of 3510 mm compared to the average value 3490 mm when the center is hit, and a variation of 20 mm occurs on average. For the FRP shaft (a) for comparison, a variation of 10 mm occurred on average, and for the steel shaft (c), a variation of 60 mm occurred on average. In addition, when looking at the standard deviation including the hitting point at the center, the FRP shaft (a) of this embodiment is 26.46, the FRP shaft for comparison (a) is 31.52, and the steel shaft (c) is In the case of the variation including the hit point at the center, the result is obtained that the shaft of the present embodiment has the least variation.
As a result of 5 mm hitting on the center, the FRP shaft (a) of this embodiment has an average value of 3477.5 mm compared to the average value 3490 mm at the center hitting, and a variation of -12.5 mm occurs on average. For the FRP shaft (a) for comparison, a variation of -5 mm occurred on average, and for the steel shaft (c), a variation of 37.5 mm occurred on average. In addition, when looking at the standard deviation including the hit points at the center, the FRP shaft (a) of this embodiment is 34.62, the FRP shaft for comparison (a) is 46.64, and the steel shaft (c) is The variation was 39.67, and the variation including the hit point at the center was the result that the shaft of this embodiment was the least dispersed.
And, looking at the overall standard deviation in consideration of the center hitting point and all the 5 mm top and bottom hitting points, the FRP shaft (a) of this embodiment is 34.67, and the FRP shaft for comparison (a) is 43 The steel shaft (c) was 40.23, and the shaft of the present embodiment gave the least variation when hitting the center and the top and bottom of the center.

(Measurement result of directionality)
As a result of the center hit, the standard deviation of the FRP shaft (a) of this embodiment is 4.15, while the comparative FRP shaft (a) is 25.59, the steel shaft (c) is The variation in directionality at the time of center hitting was 11.92, which is the smallest result in this embodiment.
As a result of 5 mm under the center, as for the FRP shaft (a) of this embodiment, the average value becomes -107.5 mm compared to the average value -101.25 mm when the center is hit, and the average variation is -6.25 mm There has occurred. For the FRP shaft (a) for comparison, a variation of 56.25 mm occurred on average, and for the steel shaft (c), a variation of 26.25 mm occurred on average. In addition, when looking at the standard deviation including the hit points at the center, the FRP shaft (a) of this embodiment is 12.36, the FRP shaft for comparison (a) is 46.20, and the steel shaft (c) is 30.36, and the variation including the hitting point at the center is the result that the shaft of the present embodiment has the least variation.
As a result of 5 mm above the center, the FRP shaft (a) of this embodiment has an average value of -91.25 mm against an average value of -101.24 mm when the center is hit, and a variation of 10 mm occurs on average . For the FRP shaft (a) for comparison, a variation of 15 mm occurred on average, and for the steel shaft (c), a variation of 6.25 mm occurred on average. In addition, when looking at the standard deviation including the hit points at the center, the FRP shaft (a) of this embodiment is 6.50, the FRP shaft for comparison (a) is 48.72, and the steel shaft (c) is 9.16, and the variation including the hitting point at the center is the result that the shaft of the present embodiment has the least variation.
And, looking at the overall standard deviation in consideration of the center hitting point and all the 5 mm top and bottom hitting points, the FRP shaft (a) of this embodiment is 12.08, and the FRP shaft for comparison (a) is 52 The steel shaft (c) was 25.04, and the shaft of this embodiment gave the most consistent results when hit at the center and above and below the center.

  From the above measurement results, when the FRP shaft (a) of this embodiment is hit at an appropriate position, the variation in distance and directionality is small compared to the comparative FRP shaft (a) and steel shaft (c). The results are obtained, and when the ball is hit with a position offset above and below the center position, although the variation in distance is slightly inferior to the FRP shaft for comparison (i), the distance for the steel shaft (iii) is There was little variation in the results. In addition, when the ball is hit with a position shift at the upper and lower positions of the center position, the result of less variation in the directionality with respect to the FRP shaft for comparison (a) is obtained, and the variation in directionality with respect to the steel shaft (c) The result was obtained that can be evaluated as equal or better. In addition to the center hitting point, in consideration of the overall variation when hitting the ball at a position shifted above and below the center position, the FRP shaft of this embodiment has a result with the least variation compared to both shafts. It was done.

  That is, according to the putter club of this embodiment, even if the variation in distance and directionality when hitting at the center C is small, and even if the ball is hit above and below the center C (the player can easily recognize that he has hit the center). There is little variation between the distance and directionality when hitting at the center. Therefore, when the player senses that the player has struck at the center (near the center), the variation in distance and directionality is small, so that a comprehensively balanced and stable putter club can be obtained.

  This is because, by constructing the FRP shaft, the rigidity on the hand side (grip side) is increased, so that the bending of the shaft before hitting is reduced, the variation in the vertical direction of the head is suppressed, and after hitting It is considered that the repulsion of the hitting ball also prevents the head from fluctuating and the shaft from returning, which also contributes to the stability of the distance and also the stability of the direction. Further, as described above, the displacement width of the ratio (GIp / EI) of the torsional rigidity and the bending rigidity in the longitudinal direction of the shaft is set to 0.5 or less so as not to largely deviate from the characteristics of the steel shaft. It can be considered that a good effect was obtained.

Next, six players (average golfers) actually put on the putter club equipped with the three shafts described above, and the sense of distance (the ball stops at the feeling of one's thought or not Shows the results of sensory tests conducted on the directionality (does it roll in the direction as I thought) and the feel at impact.
In this sensory test, each person provided the above-mentioned three putter clubs (a) (i) (i) (u) and had them put on the green freely, and the putter clubs evaluated as good were given a circle. We have you attach (we may choose plural), and we evaluate relative to putter club which we evaluated good, although we are a little inferior, have you attach △ with thing which we evaluated as allowable range (may we choose plural) I was asked to attach a cross to those that were evaluated as better by improving it relative to the putter club that was evaluated as good (multiple items may be selected).
In this case, upon evaluation of each person, the sense of weight, balance, appearance ((The weight of the FRP shaft of this embodiment is 115 g, the weight of the FRP shaft for comparison is 115 g, the weight of the steel shaft is 125 g). The steel shaft gives the impression of a sense of rigidity), and the actual hitting position movement (upper and lower movement as well as movement on the toe and heel side) is considered to have some influence, but Table 2 below The following result was obtained.

As can be seen from the above evaluation results, regarding the sense of distance, the FRP shaft (a) of this embodiment gives better results than the FRP shaft for comparison (a), and the steel shaft (c) Although inferior, the evaluation almost identical to the steel shaft was obtained. Further, regarding the directionality, the FRP shaft (a) of the present embodiment had better results than the FRP shaft (a) for comparison and the steel shaft (c). Further, with regard to feel at impact, FRP is softer than steel, so that both FRP shafts are better (FRP shaft (a) for comparison is slightly better than this embodiment).
Assuming that the evaluation of ○ is 3 points, the evaluation of 2 is 2 points, and the evaluation of x is 1 point, the putter club fitted with the FRP shaft of this embodiment is evaluated as generally good as seen in the evaluation points. can do.

Next, a configuration example of a prepreg sheet for molding an FRP shaft having the above-described characteristics will be described with reference to FIG.
FIG. 5 is a pattern diagram showing an example of the arrangement and configuration of the prepreg sheet and the reinforcing prepreg sheet capable of obtaining the bending rigidity characteristics and the torsional rigidity characteristics as described above.

  In this configuration example, the shape of the torsional rigidity distribution as shown in FIG. 1 (b) and the shape of the flexural rigidity distribution as shown in FIG. 1 (a) are obtained. It has a feature in enhancing the bending rigidity of the Specifically, in the shaft of the present embodiment, the main body prepreg sheets (main sheet) 51 to 54 are sequentially wound around the cored bar 50 whose diameter on the front end side is reduced, and the reinforcing sheets 55 to 57 from above. After winding and heating and baking in this state, it is cored and shaped by surface treatment and the like. In this case, in the metal core 50, a region having an axial length of 855 mm constitutes the total length L of the shaft.

  The main body sheet is wound a plurality of sheets to form the entire length of the shaft (forming the main body layer), and in the main body sheet 51 to be the innermost layer, reinforcing fibers are directed in the + 45 ° direction with respect to the axial length direction The first obliquely oriented sheet and the second obliquely oriented sheet in which the reinforcing fibers are oriented in the −45 ° direction with respect to the axial direction are superposed, for example, 4.0 ply at the tip end side and 3. at the proximal end side. 0 ply is cut to be wound. The same main body sheet 52 is also wound around the upper layer. Furthermore, on top of that, the reinforcing sheets are aligned in the axial direction, for example, the main sheets 53 and 54 cut so as to be wound by 2.0 plies at the tip end side and 2.0 plies at the base end side. It is wound sequentially.

  Among the main sheets wound in a plurality of sheets as described above, those in which reinforcing fibers are aligned in the axial direction contribute to the improvement of bending rigidity, and those in which reinforcing fibers are aligned in the cross direction improve the torsional rigidity. Contribute to In this case, in the present embodiment, since the shaft is hard to bend and easy to twist, the main sheets 53 and 54 in which the reinforcing fibers are oriented in the axial direction are wound on the outer layer side, and the reinforcing fibers are oriented in the cross direction on the inner layer side. By winding the body sheets 51, 52, a shaft having such characteristics is efficiently and effectively formed. In this case, if the main body sheets 51 and 52 are wound on the outer side of the main body sheets 53 and 54, it becomes possible to form the above-mentioned comparative FRP shaft (i), but such reinforcing fibers on the outer layer side In order to obtain the characteristics of the present invention, it is necessary to wind the reinforcing fiber aligned in the axial direction in order to obtain the characteristics of the present invention, when the body sheet is aligned in the cross direction. Because, it is not appropriate.

  Although it is the reinforcing fibers directed at ± 45 ° that most effectively contribute to the improvement of the torsional rigidity, the inclination angle with respect to the axial direction is not limited. In addition, as long as the above-described characteristics of the bending rigidity and the torsional rigidity can be obtained, the main body sheet in which reinforcing fibers are somewhat aligned may be wound in the circumferential direction.

  From the middle region to the proximal end region of the shaft, a reinforcing sheet 55 in which reinforcing fibers are aligned in the axial direction is wound so as to obtain a bending stiffness characteristic as shown in FIG. 2 (a). The reinforcing sheet 55 is cut from a position of 150 mm from the tip to a position covering substantially the grip area, and is cut so as to be wound by 4 plies on the tip side and 2 plies on the base end side. In this case, if the rigidity of the area to which the head is attached is increased, the flexibility in the head area is reduced compared to the steel shaft, and the feel at impact becomes hard. Feeling should be easy to be transmitted to the head side and it is preferable not to lower the feel at impact. Specifically, it is preferable not to improve bending rigidity within the range of about 200 mm from the tip of the shaft (reinforcement from 150 mm from the tip) Such an effect is exhibited by winding the sheet 55).

  Further, in the shaft of the present embodiment, a reinforcing prepreg sheet 56 in which reinforcing fibers are oriented in three axial directions (axial length direction, circumferential direction, inclined direction) is wound around an intermediate portion. The reinforcing prepreg sheet 56 is wound from a position of 256 mm from the front end to a position covering the grip portion, and is cut so as to be wound by 1 ply on the front end side and 1 ply on the rear end side.

  As described above, by winding a reinforcing prepreg sheet in which reinforcing fibers are oriented in three axial directions in the middle portion, the behavior of the head is stabilized even if the ball is shaken at the pendulum swing and misshot occurs, and the left and right direction It is possible to reduce the deviation of the

  Then, a reinforcing prepreg sheet 57 is wound around a portion to which the head is attached. The sheet for reinforcement is wound to a range of 159 mm from the tip, and the first oblique sheet and the reinforcement fibers in which the reinforcement fibers are oriented in the + 45 ° direction with respect to the axial length direction with respect to the axial length direction The second oblique sheet directed in the −45 ° direction is superimposed, and the sheet is cut so as to be wound by 2.11 plies on the tip side.

  Since the reinforcing prepreg sheet 57 is formed such that the diameter of the tip end of the shaft is reduced, the outer surface of the shaft and the inner surface of the fitting hole of the hosel portion of the head are attached to the portion where the head is attached. It has an effect of fixing in a straight shape and not reducing the strength of the fixing region and the vicinity thereof. Although a sheet in which reinforcing fibers are oriented in the axial direction may be used as a prepreg sheet for reinforcement, the bending property in the head region is reduced (the bending rigidity is increased) and the shot feeling becomes hard. It is preferable to use a cross sheet because it will

Further, when winding the prepreg sheet as described above, it is preferable that the specific gravity from the position of 200 mm from the tip to the grip portion is higher than the specific gravity from the position of 200 mm from the tip.
As described above, the swing feeling can be improved by increasing the specific gravity on the grip side from the intermediate region. In addition, as described above, by winding a reinforcing prepreg sheet 56 in which reinforcing fibers are oriented in three axial directions (axial length direction, circumferential direction, and inclination direction) around the middle portion, the grip is provided from the tip side. It is possible to increase the specific gravity of the side.

  In addition, when the thickness of the molded shaft is too thin, it is preferable that the vibration at the time of hitting a ball is easily transmitted to the grip portion or that the thickness of the shaft has a certain degree of thickness. Specifically, by making the thickness 4 mm or more over the entire length, it becomes thicker compared to the FRP shaft used in the conventional putter, and it is possible to soften the feel at impact.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to above-described embodiment, It is possible to deform | transform variously. According to the present invention, the shaft is formed such that the displacement width of the ratio of torsional rigidity to flexural rigidity (GIp / EI) is 0.5 or less over the entire length, and the torsional rigidity characteristic in the intermediate region is The structure of the main body sheets 51 to 54 and the reinforcing sheets 55 to 57 may be appropriately modified as long as such conditions are satisfied. For example, the number of plies of each sheet described above is merely an example, and in the pattern diagram shown in FIG. 5, another main body sheet may be wound, or a prepreg sheet for adjustment may be wound. You may turn it. Further, the reinforcing sheet may be wound also on the grip area on the proximal side.

  Further, the numerical value of the ratio (GIp / EI) of the torsional rigidity and the bending rigidity can be appropriately modified. In the graph shown in FIG. 3, the ratio of the steel shaft having an isotropic property is around 0.85 over the entire length, but in the present invention, the ratio is close to the feel of the steel shaft. It is preferable to form in the range of 0.5 to 1.2.

Reference Signs List 1 putter club 10 shaft made of FRP 20 putter head 21a face surface 30 grip 50 core metal 51 to 54 main body prepreg sheet 55 to 57 prepreg sheet for reinforcement

Claims (6)

In a putter club with a fiber reinforced resin shaft attached to the head,
The shaft has a ratio of torsional rigidity to flexural rigidity (GIp / EI), which decreases from the head mounting position to the middle area on the grip side, is substantially uniform from the middle area to the grip area, and is torsional rigidity over the entire length A putter club characterized in that the displacement width of the ratio of bending rigidity to that (GIp / EI) is 0.5 or less.   The putter club according to claim 1, wherein the region where the ratio of torsional rigidity to bending rigidity (GIp / EI) decreases is present at a position of 200 mm from the tip of the shaft.   In the shaft, a prepreg sheet in which reinforcing fibers are oriented in the axial direction is wound on the outer layer side, and a prepreg sheet in which reinforcing fibers are crosswise oriented to the axial direction is wound on the inner layer side. The putter club according to claim 1 or 2, which is wound over the entire length.   4. The shaft according to claim 1, wherein the specific gravity from the tip to the position of 200 mm from the tip to the grip portion is higher than the specific gravity from the tip to the position of 200 mm. The putter club described in.   The putter club according to any one of claims 1 to 4, wherein the shaft is formed to have a thickness of 4 mm or more over the entire length.   The putter club according to any one of claims 1 to 5, wherein in the shaft, a prepreg sheet in which reinforcing fibers are oriented in three axial directions is wound around an intermediate portion.