JP4253566B2 - Golf putter - Google Patents

Description

  The present invention relates to a golf putter.

The golf putter is a golf club mainly for rolling a ball on a green and putting it in a cup. Some golf putter heads concentrate weight on the toe side and heel side of the head to suppress the rotation of the head at the time of hitting and widen the sweet area (see, for example, Patent Document 1).
Japanese Patent No. 2613849

  In putting, the trajectory of the head in the putting stroke is important, and further, the orientation of the face surface at the time of impact and the hit point position (contact point between the face surface and the ball at the time of impact) are extremely important. Putting hits a small cup on a complex slanted green, and even if a slight error occurs in the hitting direction or hitting speed, the ball deviates from the small cup. This is because the trajectory of the ball rolling on the green slightly changes depending on the initial speed and launch direction of the ball, and the speed and inclination of the green. Therefore, in order to obtain good results in putting, it is necessary to control the launch direction and launch speed very accurately. To that end, the head trajectory during the stroke is stabilized, and the face during the impact is further improved. It is important to control the orientation of the surface and the location of the hit points very accurately.

However, it has been found that the accuracy of the orientation of the face surface, the head trajectory, and the hitting point position is not always sufficient in the conventional golf putter, and there is room for improvement.
That is, in the present invention, three types of inertia moments in the putter head, which were not considered at all in the prior art, were considered, and further, the characteristics of the putting stroke were considered. In other words, the putting stroke is different from other shots, such as the head speed (head speed) is much slower than the shots of other clubs such as so-called driver shots and iron shots, and the swing width is small. The behavior of the head during the stroke is also different from that of the other clubs. On the other hand, the head behavior is different between the long pad and the short pad among the putting strokes. This time, we also considered the characteristics of the head behavior based on the characteristics of the putting stroke, especially the stroke characteristics of long putts. As a result of these considerations, it has been found that a golf putter capable of further improving the various types of accuracy described above can be obtained by appropriately defining the three kinds of moments of inertia in the putter head.

  That is, an object of the present invention is to provide a golf putter that can stabilize the head trajectory in a putting stroke, particularly a long putt, and can stabilize the orientation of the face surface and the hit point position at the time of impact.

In order to achieve this object, the present invention provides three moments of inertia M1, M2 and M3 defined in the following (1) to (3) when placed on a horizontal surface in a standard installation state, where M2> The relational expression of M1> M3 and 3000 (g · cm2) ≦ M2 ≦ 7000 (g · cm2), 1000 (g · cm2) ≦ M1 ≦ 3500 (g · cm2) and 1000 (g · cm2) ≦ M3 ≦ 4000 A putter head set to a weight balance that satisfies any one of the relational expression (weight range) of (g · cm 2) and a shaft attached to the putter head are provided. .
(1) M1: moment of inertia of the head around the first axis passing through the center of gravity of the head and parallel to the face surface and the horizontal plane (2) M2: second axis that is a vertical axis passing through the center of gravity of the head Moment of inertia of the head around (3) M3: Moment of inertia of the head around the third axis passing through the center of gravity of the head and perpendicular to the first axis and perpendicular to the second axis

  In this case, since M2 is larger than M1 and M3, the rotation of the head around the second axis is stabilized, and the head behavior is stable during the putting stroke, particularly at the takeback which is the initial stage of the stroke. The orbit stabilizes. In the putting stroke, the head performs a rotational movement as well as a translational movement. The rotational movement of the head is mainly a rotation that approximates the rotation around the second axis among the three axes of the first axis to the third axis. As described above, by maximizing the second moment among the first to third moments, the rotation around the second axis, which is the reference axis of the second moment, is stabilized, so that the stroke (especially during takeback) ) The head rotation is stable and the stroke trajectory is stable. Further, since M2> M1> M3 is satisfied and the head rotation around the third axis that rotates relatively large in the long pad is stable, the head trajectory is stabilized particularly in the long pad. This action has been confirmed by the examples, and it has been found that it has a theoretical basis (tennis racket theorem). These points will be described later.

  As shown in FIG. 12, the “reference installation state” means that the golf putter is set on the horizontal plane such that the lie angle α is 71 degrees with respect to the horizontal plane, and the head is set at the lie angle. This is the state in which the posture is most stable. The reason why the lie angle is set to 71 degrees is that the lie angle of a general putter is about 70 to 72 degrees, and therefore an intermediate value thereof is adopted.

  Further, when the face surface of the head is not a plane, the “face surface” in the definition of M1 is “the two points at both ends of the ridge line of the leading edge and the ridge line that divides the top surface and the face surface of the head into two parts. It shall be replaced with a plane that passes through a total of three points.

The ratio of M1 to M2 (M1 / M2) is preferably 0.6 or more and less than 1.0. In this case, since (M1 / M2) is 0.6 or more, M1 does not become too small with respect to M2, and M1 becomes relatively large. Therefore, the head around the first axis is prevented from excessively rotating, and the hitting point position and the face surface direction are further stabilized. Since (M1 / M2) is less than 1.0, M2> M1.
Moreover, it is preferable that ratio (M3 / M1) of said M3 and said M1 is 0.9 or less. In this case, since the difference between M1 and M3 becomes large under the condition of M2>M1> M3, the rotation of the head around the third axis related to M3 is stabilized by the tennis racket theorem described later. This stabilizes the head rotation around the third axis, which rotates relatively large particularly in the long pad, and thus stabilizes the head trajectory particularly in the long pad.

  By defining M1 to M3 as described above, it is possible to provide a golf putter that can stabilize the head track during a putting stroke, particularly a long putt, and can also stabilize the orientation of the face surface and the hitting point position during impact. it can.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 12 is an overall view of the golf putter 1 according to one embodiment of the present invention. The golf putter 1 includes a head 3 having a face surface 2 for hitting a ball, a grip 10 that is a part for a player to hold the golf putter 1, and a substantially rod-shaped shaft 11. The head 3 is attached to one end of the shaft 11, and the grip 10 is attached to the other end of the shaft 11. Most of the shaft 11 has a straight bar shape, but has a bent portion only near one end where the head 3 is attached. This is for setting the lie angle and the like of the golf putter 1 appropriately. Details of this point will be described later.

FIG. 1 is a perspective view of a head 3 according to a first embodiment of the present invention attached to a golf putter 1, and FIG. 2 (a) is a plan view of the head 3 viewed from the top surface 15 side. 2 (b) is a side view of the head 3 viewed from the heel side. 4A is a front view of the head 3 viewed from the face surface 2 side, and FIG. 4B is a cross-sectional view taken along the line CC in FIG. 2A. 3A is a cross-sectional view of the head 3 taken along the line AA in FIG. 4A, and FIG. 3B is a cross-sectional view of the head 3 taken along the line BB in FIG. is there.
The head 3 is a top surface 15 constituting the upper surface thereof, a sole surface 4 constituting the lower surface thereof, a side surface 5 extending between the sole surface 4 and the top surface 15, and a plane for hitting a ball. And a face surface 2. The contour shapes of the top surface 15 and the sole surface 4 are substantially semicircular as shown in FIG.

  The head 3 has no hosel portion (neck portion) and is bonded to the shaft 11 at the shaft hole 12 (see the broken line in FIG. 1). That is, the shaft hole 12 is provided in the heel side portion of the head 3, the shaft 11 is inserted into the shaft hole 12, and the inner peripheral surface of the shaft hole 12 and the outer surface of the shaft 11 are bonded to each other. Since the axis of the shaft hole 12 is oriented substantially perpendicular to the sole surface 4, if the straight shaft 11 is inserted into the shaft hole 12, the lie angle of the golf putter 1 becomes approximately 90 degrees as a putter. It is not an appropriate lie angle. Therefore, by appropriately bending the vicinity of one end side of the shaft 11 as described above, the real loft angle, face progression, and the like including the lie angle of the golf putter 1 are set to appropriate values.

  The head 3 includes a head main body h made of an aluminum alloy or the like, and a back side weight member Jb that is partially provided on the back side of the head main body h and made of a member having a higher specific gravity than the head main body h. Although not particularly illustrated, the back side weight member Jb and the head main body h are joined by an appropriate method such as fitting press-fitting or adhesion.

  Further, the head 3 has a hollow portion k therein. That is, the head body h of the head 3 forms most of the head 3 top surface 15 and the sole surface 4 except for the back-side weight member Jb, but inside the head 3, FIG. , (B), it is divided into a face side portion hf that is substantially near the face surface 2 and a back side portion hb that is on the back side of the face side portion hf. Further, a back side weight member Jb is disposed adjacent to the back side of the back side portion hb. A portion between the top surface 15 and the sole surface 4 and without the face side portion hf, the back side portion hb, and the back side weight member Jb is a hollow portion k that is a hollow portion.

  As shown in FIG. 3A, the face-side portion hf and the back-side portion hb are separated in the face-back direction of the head 3, and therefore, as shown in the side view of FIG. Part of the portion k constitutes a penetrating portion that penetrates the head 3 from the toe side to the heel side. The back side portion hb is provided on the face side adjacent to the back side weight member Jb, but the cavity portion k extends to the toe side and the heel side of the back side portion hb.

The back-side weight member Jb has an upper surface exposed on the top surface 15 side of the head 3 and constitutes a part of the top surface 15. Further, the back side weight member Jb has a lower surface exposed on the sole surface 4 side of the head 3 and constitutes a part of the sole surface 4.
Further, as shown in FIG. 3A, in the most back side portion of the head 3 (near the vertex on the back side), the contour shape of the back side portion hb is the contour of the head 3 (top surface 15 and sole surface 4). The shape is substantially the same, but the contour shapes are not the same except for the vicinity of the apex, and the contour shape of the back side portion hb is closer to the inner side of the head 3 than the contour shape of the head 3. Yes. As a result, the cavity k also exists on the toe side and the heel side of the back side portion hb.

  Further, as shown in FIG. 3A, the structure of the face side portion hf in the head body h is such that the volume (weight) is concentrated on the toe side portion and the heel side portion, while the toe / heel direction. The central portion is provided with a relatively thin plate-like portion. Therefore, as shown in FIGS. 3A and 3B, the cavity k is particularly widely distributed near the center of the head 3 in the toe-heel direction.

  The side surface 5 is a surface extending between the top surface 15 and the sole surface 4 and excluding the face surface 2. In this head 3, the side surface 5 is the toe side and the heel side surface of the face side portion hf. And, it exists only in the side surface near the back side vertex of the back side weight member Jb, and the side surface 5 does not exist in the other part (refer to the perspective view of FIG. 1). This is because, as described above, the cavity k is open from the inside of the head to the outside of the head. Thus, by providing the hollow portion k in the head 3 and dividing the inside of the head main body h into the back side portion hb and the face side portion hf, the degree of freedom in designing the weight distribution of the head 3 becomes extremely high. Further, the degree of freedom for setting the inertia moments M1 to M3 described later is also increased.

  Here, for the head 3, three axes of a first axis A1 to a third axis A3 as shown in FIG. 1 are defined. In this definition, the head 3 in the reference installation state as described above is considered. The first axis A1 passes through the center of gravity G of the head 3 and is parallel to the face surface 2 and the horizontal plane in the reference installation state. The second axis A <b> 2 is a vertical axis that passes through the center of gravity G of the head 3. The third axis A3 is an axis that passes through the center of gravity G of the head 3 and is perpendicular to the first axis A1 and perpendicular to the second axis A2. The inertia moment of the head 3 around the first axis A1 is defined as a first moment M1, the inertia moment of the head 3 around the second axis A2 is defined as a second moment M2, and the inertia moment of the head 3 around the third axis A3 is defined as The third moment M3 is assumed.

  In the head 3 according to the first embodiment, these M1 to M3 satisfy the relational expression of M2> M1> M3, and (M1 / M2) is 0.6 or more and less than 1.0. Furthermore, (M1 / M2) is set to 0.9 or less.

The head 3 configured as described above has the following operational effects.
First, since the second moment M2 is larger than the third moment M3 and the first moment M1, the rotation of the head 3 around the second axis A2 is stable, and the behavior of the head 3 is stable during the putting stroke, particularly during takeback. To do. Therefore, the stroke, especially the takeback trajectory is stabilized. In the putting stroke, the head 3 performs a rotational movement together with a translational movement. The rotational movement of the head is mainly the rotation that approximates the rotation around the second axis among the three axes of the first axis A1 to the third axis A3. As described above, by maximizing the second moment M2 among the first moment M1 to the third moment M3, the rotation of the head 3 around the second axis A2, which is the reference axis of the second moment M2, is stabilized. That is, the rotation of the head 3 during the stroke is stabilized, and the stroke trajectory is stabilized. The rationale is derived from the tennis racket theorem described later.

Furthermore, since M2>M1> M3, the head rotation around the third axis in addition to the head rotation around the second axis is relatively stable compared to the head rotation around the first axis, so that it is particularly long. The head trajectory becomes stable in the pad.
The putting stroke has a smaller swing width than a normal shot in a golf club other than the putter. Further, in such a putting stroke, the long pad has a relatively large swing width. Here, the long putting means that the distance to the target (cup) is about 4 m or more.

In addition to the rotation about the second axis A2, the rotation about the first axis A1 is relatively large, but the rotation about the third axis A3 is relatively small. On the other hand, in the case of the long pad, the rotation around the third axis A3 is relatively larger than that in the case of the short pad, and the influence of the head rotation around the third axis A3 on the stroke trajectory becomes large.
Therefore, the second moment M2 is maximized and the third moment M3 is minimized among the first moment M1 to the third moment M3, so that the second axis A2 having a relatively large rotation and particularly the long pad has a large influence. The head rotation around the three axes A3 can be stabilized. Therefore, the head trajectory is stabilized particularly during the long pad stroke. The rationale is the tennis racket theorem described later.

In the head 3 according to the first embodiment, these M1 to M3 satisfy the relational expression of M2>M1> M3, and (M1 / M2) is 0.6 or more and less than 1.0. ing. In this case, since (M1 / M2) is 0.6 or more, M1 does not become too small with respect to M2, and M1 becomes relatively large. Therefore, M1 can be increased while maintaining the relationship of M2>M1> M3, and the head around the first axis is prevented from rotating excessively. Therefore, the hit point position and the orientation of the face surface are further stabilized.
Further, since the ratio of M3 to M1 (M3 / M1) is set to 0.9 or less, the difference between M1 and M3 increases under the condition of M2>M1> M3. Thus, the rotation of the head around the third axis related to M3 is further stabilized. As a result, the head rotation around the third axis, which has a great influence on the long pad, is stabilized, so that the head trajectory is stabilized especially on the long pad.

Next, the theoretical basis of the present invention described above will be described. The following explanation of Euler's equation of motion (Euler's theorem) is “For Mechanics and New Perspectives” published by Baifukan Co., Ltd. (VD Barger and MG Olson, co-translated by Toda Morikazu and Tagami Yukiko The first edition was issued on January 20, 19th, and the 17th edition was issued on November 30, 1987). Using three Euler equations of rigid bodies with different main moments of inertia, the following results can be obtained in the movement around each axis. The values of inertia moments (main inertia moments) around the respective axes x, y, and z, which are three inertial main axes orthogonal to each other, are I _x , I _y , and I _z , respectively. In addition, it is assumed that the inequality I _x <I _y <I _z holds. Since gravity is a uniform force near the surface of the earth, there is no moment of gravity around the center of gravity of the rigid body. If the moment of force due to wind pressure is ignored, Euler's equation of motion is as follows:

Here, from the orthogonal axis theorem, the following equation (2) holds.
I _z = I _x + I _y (2)
The relationship (2) into equation _(1), r ₌ the put and _{(I y -I x) / (} I y + I x), the following equation (3) to (5) is obtained.

Here, if the smallest I _x among I _x , I _y , and I _z is very small compared to I _y , an approximation of r≈1 can be used. Hereinafter, qualitative motion characteristics are assumed when the rigid body is assumed to rotate mainly around one of the three main axes.

If the initial rotation is about axis x, the product ω _z ω _y appearing in equation (3) can be ignored. Then, it can be seen that ω _x becomes constant. That is, as shown in the following equation (6), ω _x is constant at the initial value ω _x (0).
ω _x = ω _x (0) (6)
In order to solve the remaining two equations (4) and (5), a complex variable such as the following equation (7) may be introduced.

  Therefore, Formula (4) and Formula (5) become like the following Formula (8) and Formula (9), respectively. By combining Expression (8) and Expression (9) into one expression for the complex variable of Expression (7), Expression (10) is established. The differential equation represented by the equation (10) has an exponential solution as the following equation (11).

Therefore, the corresponding ω _y and ω _z are as a function of time t:
ω _y (t) = a · sin (ω _x t + α) (12)
ω _z (t) = a · cos (ω _x t + α) (13)
It can be expressed as. Since the amplitude a is small due to the initial condition, it can be seen that both the values of the two angular velocity components of the equations (12) and (13) are always small. In such an approximate solution, the following equations (14) and (15) are obtained.

  Therefore, the angular velocity vector ω shown in the following equation (16) precesses by drawing a small cone around the main axis x. This is why the rotational movement about the axis x is stable.

When initially rotating around the axis z, the solution of the Euler equation is similar to the one just handled. When r = 1, the mathematical structure of each of the three formulas (3), (4), and (5) does not change even if ω _x and ω _z are interchanged. Therefore, the following approximate solutions (17) to (19) are obtained following the equations (6), (12), and (13).
ω _z (t) = ω _z (0) (17)
ω _x (t) = a · cos (ω _z t + α) (18)
ω _y (t) = a · sin (ω _z t + α) (19)
Again, the rotational movement about the axis is stable.

However, the situation is different if the initial rotation is about the inertial axis y. In this case, ignoring the product ω _x ω _z in the beginning (4),
ω _y (t) = ω _y (0) (20)
Is obtained. Next, if a sum and a difference are made from the equations (3) and (5), the following equations (21) and (22) are obtained. The solutions of these linear combinations are as shown in equations (23) and (24), respectively. If these equations (23) and (24) are solved to obtain ω _x and ω _z , equations (25) and (26) are obtained.

In this motion, the angular velocities around the two axes, axis x and axis z, both increase rapidly with time, and the rigid object will tip over. The form of the solution clearly given by Equation (20), Equation (25), and Equation (26) is limited to the time when the object is rotated and thrown up, so long as there is not much time after throwing up. That is, it is correct only while ω _x ω _z can be ignored in Equation (4). In this way, the object has a stable rotational movement around the inertial main axis where the moment of inertia around each of the three inertial main axes is the maximum or minimum value, and rotation around the other inertial main axes. Movement becomes unstable. This conclusion is called the tennis racket theorem.

This conclusion can be explained with a simple model as follows. A simple (solid) flat plate having a length L in the longitudinal direction, a width W, and a thickness T as shown in FIG. 13 is considered as a model. In this model, the moments of inertia around the three principal axes of inertia pass through the center of gravity G of the flat plate and the moment of inertia I _x about the x axis parallel to the upper and lower surfaces of the flat plate and the side on the long side. An inertia moment I _y around the y axis that is parallel to the top and bottom surfaces and perpendicular to the x axis, and an inertia moment I _z that passes through the center of gravity G and is perpendicular to the top and bottom surfaces around the z axis. As shown in FIG. 13, the flat plate has a shape in which the length L in the longitudinal direction is longer than the width W and the width W is longer than the thickness T. Obviously, the magnitude relationship between the moments of inertia about the three principal axes of inertia is I _z > I _y > I _x . That is, I _z is the largest, then I _y is the largest, and I _x is the smallest.

  From the above conclusion, when rotating around the axis with the maximum or minimum moment of inertia among the three main axes of inertia, it rotates stably as it is, while the moment of inertia of the three main axes of inertia is maximum or minimum. It can be seen that if the rotation is performed around an axis that does not exist, the rotation occurs around all three inertial main axes and the rotation becomes unstable. When this is applied to this flat plate, it becomes as follows. Consider a case where this flat plate is rotated in any of the three principal axes of inertia, the x-axis, y-axis, and z-axis, and thrown into the air. If the initial rotation is about either axis x or axis z, the plate continues to rotate stably. On the other hand, if the initial rotation is about the axis y, the rotational movement will quickly become irregular and rotation will occur around all three inertial axes.

  Although the above document does not describe that Euler's theorem can be applied to a golf putter head, the present invention has found that this can be applied to a golf putter head. Here, as described above, as shown in FIG. 1, three axes of the first axis A1, the second axis A2, and the third axis A3 that are orthogonal to each other are defined for the golf putter head. The first axis A1 is an axis in a direction coinciding with the toe / heel direction of the head. The second axis A2 is an axis in the vertical direction passing through the center of gravity of the head, and is an axis in a direction coinciding with the top / sole direction of the head. The third axis A3 is an axis that passes through the center of gravity of the head and is perpendicular to the first axis and perpendicular to the second axis. Therefore, the third axis A3 is an axis in the face / back face direction of the head.

  In the putting stroke, the head performs a rotational motion as well as a translational motion. During this stroke, particularly in take-back, it can be said that the rotational movement of the head is mainly the rotation close to the rotation around the second axis among the three axes of the first axis A1, the second axis A2, and the third axis A3. The reason is as follows.

  It is inevitable that the head rotates around the shaft axis not only in the putting stroke but also in a normal full shot. In other words, when a person who is a golfer swings, it is impossible to swing without changing the orientation of the face surface because of the swing structure, and the head rotates around the shaft axis. Then, the head is rotating around the second axis A2. Furthermore, when swinging with a large swing such as a shot such as a normal driver shot or an iron shot, especially a shot close to a full shot, the posture of the head changes greatly and the first axis A1 and the third axis A3 around The rotation is also relatively large. On the other hand, since the swing width is small in the putting stroke, the rotation around the first axis A1 and the rotation around the third axis A3 are relatively small, and are smaller than the rotation around the second axis A2. From the above, it is considered that the rotation of the head in the putting stroke is mainly the rotation that approximates the rotation around the second axis A2.

  Furthermore, the swing width of a long pad is larger than that of a short pad among the putting strokes. Therefore, the rotation of the head around the third axis A3 during the stroke becomes larger than that of the short pad, and the rotation around the third axis A3 greatly affects the stability of the stroke. According to the tennis racket theorem described above, when the magnitude relationship of M2> M1> M3 is established, the rotation around the first axis A1, which is the reference axis of the third moment M1 where the moment of inertia is not the maximum or minimum, is relatively unstable. However, in the long pad, the influence on the stroke of the rotation around the first axis A1 is relatively small. Therefore, the head trajectory during the long pad stroke is stabilized by preferentially stabilizing the rotation around the second axis A2 and the third axis A3, which has a relatively large influence on the stability of the stroke.

  When the rotation of the head about the second axis A2, which is the reference axis of the second moment M2, is stabilized, the orientation of the face surface 2 is stabilized, so that the striking point position and the ball launch direction are stabilized. Further, since the main rotation at the time of the stroke is a rotation approximate to the rotation around the second axis A2, the behavior around the stroke of the head 3 (especially at the time of takeback at the initial stage of the stroke) is achieved by stabilizing the rotation around the second axis A2. In addition, the behavior of the initial take-back from the head stationary state to the operating state is stabilized, and the head trajectory becomes stable. In the long pad, as described above, the influence of the rotation about the third axis A3 is relatively larger than the rotation about the first axis A1. Therefore, the head trajectory during the stroke is stabilized by giving priority to the rotation around the second axis A2 and the third axis A3 over the rotation around the first axis A1.

  Although the three axes of the first axis A1, the second axis A2, and the third axis A3 in the putter head are usually not completely coincident with the main axis of inertia of the putter head, the conclusion from the Euler equation is approximated. It is considered applicable. Moreover, by thinking in that way, the test result by the below-mentioned Example can be demonstrated.

  As described above, it is preferable that (M1 / M2) is 0.6 or more because M1 does not become too small with respect to M2 and M1 becomes relatively large. However, for the same reason, (M1 / M2) ) Is preferably 0.61 or more, and more preferably 0.68 or more. In order to satisfy the relationship of M2> M1, (M1 / M2) is less than 1.0. However, if this value is too close to 1.0, the difference between M1 and M2 becomes small, and the tennis racket theorem. The effect of M2> M1> M3 based on the above tends to decrease. Therefore, (M1 / M2) is more preferably 0.9 or less, and further preferably 0.8 or less.

  As described above, it is preferable that (M3 / M1) is 0.9 or less because the difference between M1 and M3 becomes large and the rotation of the head around the third axis related to M3 becomes more stable. For the same reason, (M3 / M1) is more preferably 0.86 or less, and even more preferably 0.74 or less. On the other hand, if (M3 / M1) is too small, it may be difficult to produce the head. Therefore, (M3 / M1) is preferably 0.4 or more, and more preferably 0.5 or more.

If the second moment M2 is too small, it is difficult to set the second moment M2 to be larger than the first moment M1 and the third moment M3. Further, when the second moment M2 is small, the head rotation around the second axis A2 is likely to occur, and the change in the orientation of the face surface tends to be large and the hitting ball direction and the hit point position tend to vary. Therefore, the second moment M2 is preferably 3000 (g · cm ² ) or more, more preferably 3100 (g · cm ² ) or more, and particularly preferably 4200 (g · cm ² ) or more.
If the second moment M2 is too large, the weight of the head may become too large, or the head shape may be uncomfortable, so it is preferably 7000 (g · cm ² ) or less, and 6000 (g · cm ² ) or less. Is more preferable, and 5000 (g · cm ² ) or less is particularly preferable.

If the first moment M1 becomes too small, head rotation around the first axis A1 is likely to occur, so that the hitting point position is likely to vary in the top / sole direction (vertical direction) and duffing is also likely to occur. Furthermore, it becomes difficult to set the magnitude relationship of M1> M3. Accordingly, the first moment M1 is preferably 1000 (g · cm ² ) or more, more preferably 1900 (g · cm ² ) or more, and particularly preferably 2900 (g · cm ² ) or more. If the first moment M1 is too large, the head weight may become too large, the head shape may become uncomfortable, and it may be difficult to set the magnitude relationship of M2> M1, so 3500 (g · cm ² ) Or less is preferable, and 3000 (g · cm ² ) or less is more preferable.

If the third moment M3 is too small, head rotation around the third axis A3 is likely to occur, and the hit point position tends to vary in the top / sole direction (vertical direction) and the toe / heel direction (left / right direction). The variation in the sole direction (vertical direction) tends to increase. Therefore, M3 is preferably 1000 (g · cm ² ) or more, particularly preferably 1600 (g · cm ² ) or more. If the third moment M3 is too large, the head weight may become too large, or the head shape may become uncomfortable. Further, it becomes difficult to set M1> M3. Accordingly, it is preferably 4000 (g · cm ² ) or less, and more preferably 3500 (g · cm ² ) or less.

  The material of the head is not particularly limited, and a material usually used as a golf putter head can be used. As the material of the head main body, for example, iron-based metals such as brass and soft iron, stainless steel, aluminum alloy, titanium, titanium alloy and the like can be used. These materials can be used singly or in combination. Moreover, when using the weight member J or the back side weight member Jb as in the above-described embodiment, the material of the weight member J or the like includes copper, brass, tungsten, a tungsten alloy such as W-Ni or W-Cu, High specific gravity materials such as can be used. Further, when the weight member J or the like is used in this way, if aluminum or aluminum alloy having a particularly low specific gravity is used as the head main body h, the difference in specific gravity from the weight member J or the like becomes large, and the design flexibility of the weight distribution of the head 3 is increased. It is preferable in terms of improvement.

(Example)
The effect of the present invention was confirmed by examples and comparative examples. Two examples and two comparative examples were produced. The four types of heads of Examples 1 and 2 and Comparative Examples 1 and 2 have the same shape, the head weight is 374 g, the head height Hh is 27 mm, the head width Hw is 97 mm, and the head depth Hd is It was made common at 85.5 mm. The material of the weight member J and the back side weight member Jb was copper, and the material of the head body h was an aluminum alloy.

  The head 3 of Example 1 was configured as shown in FIGS. 1 to 4 as in the first embodiment. The thickness of the thin portion near the center of the face surface is set to 5 mm for Tf (see FIG. 3A), and the thickness Tc of the head body h on the top side of the cavity k (see FIG. 3B) is set to 3 mm. The thickness Ts of the head body h on the sole side of the cavity k was 3 mm. Further, the height Hc of the back side weight member Jb was 23 mm, and the length Dc of the back side weight member Jb in the face-back direction was 22 mm (see FIG. 2).

The form of the head 3 according to the second embodiment is shown in FIGS. FIG. 5A is a plan view of the head 3 according to the second embodiment viewed from the top surface side, and FIG. 5B is a side view of the head 3 viewed from the heel side. 6A is a cross-sectional view taken along the line AA in FIG. 5B, and FIG. 6B is a cross-sectional view taken along the line BB in FIG. 5A.
In the second embodiment, the back side weight member Jb in the first embodiment is replaced with the back side portion hb of the head body h, and the back side weight member Jb does not exist. A central weight member Js extending in the face / back direction is provided between the face side surface of the back side portion hb and the head inner side surface (back surface) of the face surface 2. The central weight member Js is made of copper and is a straight bar member having a rectangular cross section whose longitudinal direction is oriented in the face-back direction, and is provided so as to fill a space between the top surface 15 and the sole surface 4. (See FIG. 6B). Further, compared with the first embodiment, the weight of the toe side portion and the heel side portion of the face side portion hf in the head body h is reduced. The thickness of the thin portion near the center of the face surface is set to 5 mm for Tf (see FIG. 6A), and the thickness Tc of the head body h on the top side of the central weight member Js (see FIG. 6B) is set to 3 mm. The thickness Ts of the head main body h on the sole side of the central weight member Js was 3 mm.

  The form of the head 3 according to Comparative Example 1 is shown in FIGS. FIG. 7A is a plan view of the head 3 according to Comparative Example 1 as viewed from the top surface side, and FIG. 7B is a side view of the head 3 as viewed from the heel side. 8A is a cross-sectional view taken along the line AA in FIG. 7B, and FIG. 8B is a cross-sectional view taken along the line BB in FIG. 7A.

  In Comparative Example 1, the back side portion hb of the head main body h is provided at the same position and size as in Example 2. The shape of the face side portion hf of the head body h is based on the face side portion hf of the first embodiment, and the weight member J is joined to the toe side and the heel side. The weight member J itself is a solid member and is made of copper having a specific gravity larger than that of the head body h. The upper surface and the lower surface of the weight member J form a part of the top surface 15 and the sole surface 4 smoothly and continuously with the upper surface and the lower surface of the head body h. Further, the side surface of the weight member J constitutes a part of the side surface 5. The toe-heel direction width Wc (see FIG. 7A) of the weight member J is 12 mm.

The form of the head 3 according to Comparative Example 2 is shown in FIGS. 9A is a plan view of Comparative Example 2 viewed from the top surface side, and FIG. 9B is a side view of the Comparative Example 2 viewed from the heel side. 10A is a cross-sectional view taken along line AA in FIG. 9B, FIG. 10B is a cross-sectional view taken along line BB in FIG. 9A, and FIG. It is sectional drawing in the CC line of Fig.9 (a).
In Comparative Example 2, the cavity k is made larger than those in Examples 1 and 2 and Comparative Example 1 described above, the back side portion hb is not provided in the head body h, and the back side weight member Jb is also provided. Not. The cavity k is opened not only on the toe side and heel side of the head 3 but also on the back side of the head 3.

  The face surface 2 of the head 3 of this comparative example 2 is made of a flat face plate Fp made of an aluminum alloy having the same contour shape as the face surface 2, and on the back side of the face plate Fp, A thick plate-like head front portion hz having substantially the same shape as the face plate Fp and thicker than the face plate Fp is provided in parallel with the face plate Fp. Further, a head rear portion hk is provided on the back side of the head front portion hz. As shown in FIG. 11, the head rear portion hk is opened with a shape substantially the same as the contour shape of the head front portion hz on the face surface side, and a part of the head rear portion hz on the rear side is formed in the opening. By fitting, the head front part hz and the head rear part hk are joined. Further, the inside of the head rear portion hk is a cavity except for one standing pillar 20 erected between the inner surface on the top surface 15 side and the inner surface on the sole surface 4 side, and this cavity is the cavity portion k of the head 3. It is said that. The hollow portion k is open to the head rear side, the head toe side, and the heel side in the head 3.

  The head front portion hz has a heel-side portion and a toe-side portion made of brass, and a center portion in the toe-heel direction is made of an aluminum alloy. The toe-heel direction length Ft of the toe-side portion is 42 mm, the toe-heel direction length Fh of the heel-side portion is 17 mm, and the toe-heel direction length Fc of the center portion made of aluminum alloy is 38 mm. It is said that. The thickness Tn of the face plate Fp is 3 mm, the thickness Tm of the head front part hz is 16 mm, and the fitting length Tk of the head front part hz to the head rear part hk is 3 mm.

  Unlike Comparative Example 1 and Examples 1 and 2, Comparative Example 2 has a hosel 21 (see FIG. 9B). The hosel 21 is made of brass having an axial length of 70 mm, but is a so-called over hosel. The hosel 21 is inserted into the pipe-shaped shaft 11 and bonded to the head 3 to be bonded to the head 3. 11 is attached. As shown in FIG. 9B, a step substantially the same as the wall thickness of the shaft 11 is provided in the midway position of the hosel 21 in the axial direction, and the end surface of the shaft 11 is in contact with the step. The shaft 11 and the head 3 are bonded (see FIG. 9B).

  As described above, in Examples 1 and 2 and Comparative Examples 1 and 2, the position and size of the cavity k, the specific gravity of the head body h, the presence or absence of the face side portion hf, the position and size thereof, and the back side Presence / absence and position / size of portion hb, presence / absence / position / size of weight member J on toe side and heel side, specific gravity of weight member J, presence / absence of back side weight member Jb, position / size thereof, back By appropriately adjusting the specific gravity of the side weight member Jb, the presence / absence and position / size of the head front portion hz, the presence / absence of the hosel 20 and the material / length / position thereof, etc., the degree of freedom in head design is increased. The first moment M1 to the third moment M3 are set to desired values.

The test was performed on two items of sensory evaluation and track variation after using the same shaft and the same grip in all the examples and comparative examples, and unifying the club weight at 560 g. The test was a human hitting test with 12 testers (all right-handed), and the test was performed with a 4 m putting to the target (cup).
The test results are shown in Table 1.

The “open angle difference σ” described in Table 1 will be described.
The opening angle difference σ is an index indicating the stability of the face surface direction (left-right direction) at the time of hitting, and the smaller the value, the higher the stability.
The open angle indicates the left-right direction deviation angle of the face direction with respect to the target direction, and how many times the face direction is deviated with respect to the target (cup) in a plan view when the head in the stroke is viewed from above. Is shown. A state where the face is square with respect to the target is an opening angle of 0 degree. The opening angle was measured by taking an image at 60 frames / second using a CCD video camera and obtaining the opening angle from the image.
The difference in opening angle means that the opening angle at the moment when the head hits the ball during the stroke (impact moment) is the opening angle 1, and the opening angle of the head (head moving toward the ball) 20 cm before the ball is opened. When the angle is 2, it is given by (open angle 2−open angle 1). The opening angle when the face turns to the right with respect to the target (cup) is positive, and the opening angle when the face faces the left is negative. The σ of the opening angle difference is a value obtained by averaging the data for 12 persons by obtaining the standard deviation of the opening angle difference in each tester when each tester takes 20 shots.

Next, the contents of “sensory evaluation” described in Table 1 will be described.
As described above, twelve testers made 20 hits (putting) for each test club and performed sensory evaluation on the stability of the stroke (hardness of blur). Each tester evaluated for each club whether it felt the stroke was stable or the stroke felt unstable. And, when the tester who felt that the stroke was stable was 10 or more out of 12, ◎, the case of 8-9, ○, the case of 6-7, △, “stroke The case where there were 7 or more people who felt that “is unstable” was rated as x.

  Comparing the example and the comparative example, the examples 1 and 2 have a smaller opening angle difference σ and a stable face orientation and superior sensory evaluation compared to the comparative examples 1 and 2. The result is sexual.

  Note that the measurement of the first moment M1 to the third moment M3 was performed using INEATIA DYNAMICS. It measured by the inertia moment measuring device of MODEL NUMBER RK / 005-002 made by INC. The measurement was performed by fixing the head with clay so that each axis of the head coincides with the rotation axis of the moment of inertia measuring device. In the measurement procedure, the moment of inertia was first measured with the head fixed with clay, and then the head was removed without changing the shape of the clay, and the moment of inertia of the clay alone was measured. From these values, the moment of inertia of the head only was calculated.

  A so-called toe heel balance type putter head as shown in FIG. 14, for example, is widely known as a conventional golf putter head. In this head, by concentrating the weight on the toe portion 30 and the heel portion 31, the rotation of the head at the time of hitting is suppressed and the sweet area is expanded. When the weight is concentrated on the toe side and the heel side of the head, the second moment M2 around the second axis A2 is increased as compared with the case where the weight is substantially uniformly distributed from the toe side to the heel side. At the same time, the third moment M3 about the third axis A3 also increases. In the conventional toe heel balance type putter head, the second moment M2 increases and the third moment M3 also increases. As a result, the third moment M3 is larger than the second moment M2. Thus, in the conventional putter head, the second moment M2 never becomes larger than the third moment M3 and the first moment M1. Conventionally, since no consideration was given to the three axes of the first moment M1 to the third moment M3, the magnitude relationship between the three parties of M1 to M3 was not taken into consideration. The present invention defines this magnitude relationship.

In order to manufacture a head having a large first moment M1, a large amount of weight may be distributed to a position as far as possible from the first axis A1. The opposite is true to make it smaller. For example, when the first moment M1 is reduced, the head depth Hd may be reduced, or the back-side weight member Jb may be lightened, for example.
In order to produce a head having a large second moment M2, a large amount of weight may be distributed to a position as far as possible from the second axis A2. The opposite is true to make it smaller. For example, in order to increase the second moment M2, the head width Hw may be increased, or the weight member J disposed on the toe side and the heel side of the head 3 may be adjusted to be appropriate.
In order to produce a head having a large third moment M3, a large amount of weight may be distributed to a position as far as possible from the third axis A3. The opposite is true to make it smaller. For example, in order to reduce the third moment M3, the head height Hh may be reduced, or the head width Hw may be reduced as appropriate.

  In the present invention, it is preferable to set the head specifications as follows. This is because it becomes easy to set the weight balance of the putter head to a weight balance satisfying M2> M1> M3. First, the depth of the center of gravity is preferably 10 mm or more, more preferably 15 mm or more, and preferably 25 mm or less. The center of gravity depth is a value measured from the leading edge. The height of the center of gravity is preferably 20 mm or less, more preferably 15 mm or less, and preferably 5 mm or more. Further, the ratio Hw / Hd of the head width Hw to the head depth Hd is preferably 1.1 or more, and the upper limit is preferably 2.8 or less, more preferably 2.0 or less. Further, the head height Hh is preferably 20 mm or more, and preferably 35 mm or less. The head weight is preferably 280 g or more, more preferably 320 g or more, and preferably 400 g or less, more preferably 380 g or less.

It is a perspective view of the putter head with which the golf putter in one embodiment (and Example 1) of the present invention was equipped. (A) is the top view which looked at the putter head of FIG. 1 from the top surface side. (B) is the side view seen from the heel side. (A) is sectional drawing in the AA line of FIG.2 (b), (b) is sectional drawing in the BB line of Fig.2 (a). (A) is the front view which looked at the putter head of FIG. 1 from the face surface direction, (b) is sectional drawing in CC line of Fig.2 (a). (A) is the top view which looked at the putter head with which the golf putter of Example 2 was mounted | worn from the top surface side, (b) is the side view seen from the heel side. (A) is sectional drawing in the AA line of FIG.5 (b), (b) is sectional drawing in the BB line of Fig.5 (a). (A) is the top view which looked at the head concerning the comparative example 1 from the top surface side, (b) is the side view seen from the heel side. (A) is sectional drawing in the AA line of FIG.7 (b), (b) is sectional drawing in the BB line of Fig.7 (a). (A) is the top view which looked at the head concerning the comparative example 2 from the top surface side, (b) is the side view seen from the heel side. (A) is sectional drawing in the AA line of FIG.9 (b), (b) is sectional drawing in the BB line of Fig.9 (a). It is sectional drawing in the CC line of Fig.9 (a). 1 is an overall view of a golf putter that is one embodiment of the present invention. It is a figure for demonstrating the theorem of a tennis racket. It is a perspective view which shows an example of the conventional putter head.

Explanation of symbols

1 Golf putter 2 Face surface 3 Head G Center of gravity M1 First moment M1
M2 Second moment M2
M3 Third moment M3
A1 1st axis A2 2nd axis A3 3rd axis

Claims (5)

The three moments of inertia M1, M2 and M3 defined by the following (1) to (3) when placed on a horizontal surface in the standard installation state are M2>M1> M3 and 3000 (g · cm 2). ) ≦ M2 ≦ 7000 (g · cm 2) , a putter head set to a weight balance that satisfies the relational expression ;
A golf putter comprising: a shaft attached to the putter head .
(1) M1: Moment of inertia of the head around a first axis passing through the center of gravity of the head and parallel to the face surface and the horizontal plane. (2) M2: Second axis which is a vertical axis passing through the center of gravity of the head. Moment of inertia of the head around (3) M3: Moment of inertia of the head around the third axis passing through the center of gravity of the head and perpendicular to the first axis and perpendicular to the second axis The three moments of inertia M1, M2, and M3 defined by the following (1) to (3) when placed on a horizontal surface in the reference installation state are M2> M1> M3 and 1000 (g · cm 2). ) ≦ M1 ≦ 3500 (g · cm 2), a putter head set to a weight balance that satisfies the relational expression;
A golf putter comprising: a shaft attached to the putter head.
(1) M1: Moment of inertia of the head around the first axis passing through the center of gravity of the head and parallel to the face surface and the horizontal plane
(2) M2: Moment of inertia of the head about the second axis that is a vertical axis passing through the center of gravity of the head
(3) M3: Moment of inertia of the head about the third axis that passes through the center of gravity of the head and is perpendicular to the first axis and perpendicular to the second axis The three moments of inertia M1, M2, and M3 defined by the following (1) to (3) when placed on a horizontal surface in the reference installation state are M2> M1> M3 and 1000 (g · cm 2). ) ≦ M3 ≦ 4000 (g · cm 2), a putter head set to a weight balance that satisfies the relational expression;
A golf putter comprising: a shaft attached to the putter head.
(1) M1: Moment of inertia of the head around the first axis passing through the center of gravity of the head and parallel to the face surface and the horizontal plane
(2) M2: Moment of inertia of the head about the second axis that is a vertical axis passing through the center of gravity of the head
(3) M3: Moment of inertia of the head about the third axis that passes through the center of gravity of the head and is perpendicular to the first axis and perpendicular to the second axis The golf putter according to any one of claims 1 to 3, wherein a ratio (M1 / M2) between the M1 and the M2 is 0.6 or more and less than 1.0. The golf putter according to any one of claims 1 to 4, wherein a ratio (M3 / M1) between the M3 and the M1 is 0.9 or less.

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