JP4339073B2 - 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. This time, we also considered the characteristics of the head behavior based on the characteristics of the putting stroke, especially the stroke characteristics of the short putt. 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 a head stroke in a putting stroke, particularly a short putt, and can stabilize the orientation of the face surface and the hitting 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 by the following (1) to (3) when placed on a horizontal surface in a standard installation state:
M2>M3> M1
And satisfy the relational expression
A putter head set to a weight balance where the value of (M3-M1) is 50 (g · cm ² ) or more and 1500 (g · cm ² ) or less ;
The putter head is used for hitting a ball, a top surface constituting the upper surface of the putter head, a sole surface constituting the lower surface of the putter head, a side surface extending between the sole surface and the top surface, and And a face surface that is a plane of
The putter head has a height of 20 to 35 mm, and
The golf putter has a weight of 280 to 400 g .
(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

  In this case, since M2 is larger than M3 and M1, the rotation of the head around the second axis is stabilized, and the head behavior is stable during the putting stroke, particularly during 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> M3> M1, the head rotation around the first axis is stabilized, so that the head trajectory is stabilized particularly in a short pad. This action has been confirmed by the examples, and has been found to have a further theoretical basis. These points will be described later.

Moreover, since the value of (M3-M1) is 1500 (g · cm ² ) or less, M3 becomes too large and M3 becomes larger than M2 or the difference between M3 and M2 becomes small. Is suppressed, and the effect described above (the effect of making M2 larger than M3 and M1) becomes remarkable. Or, if M1 becomes too small, it becomes easy to rotate around the first axis and the hitting point position varies in the vertical direction, but such hitting point variation is suppressed. Furthermore, since the value of (M3−M1) is 50 (g · cm ² ) or more, the above-described effect when M3> M1 is reliably achieved.

  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.

The M2 is preferably 4000 (g · cm ² ) or more, and the M3 is preferably 2500 (g · cm ² ) or more.
If M2 is 4000 (g · cm ² ) or more, it is easy to set M2 to a value larger than M1 and M3, so that the head trajectory is easily stabilized as described above. Further, since M2 is made large, the head is difficult to rotate around the second axis, so that the orientation of the face surface is difficult to vary in the left-right direction and the hitting point position is difficult to shift. In addition, since M3 is 2500 (g · cm ² ) or more, it is easy to set the magnitude relationship of M3> M1, the head rotation around the third axis is stable, and the hit point position is difficult to shift.

  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.

  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 short putt, and can also stabilize the orientation of the face surface and the hit 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. The shaft 11 is almost a straight bar, 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 the head 3 attached to the golf putter 1, FIG. 2 (a) is a plan view of the head 3 viewed from the top surface 15 side, and FIG. 2 (b) is a view from the heel side. FIG. 3A is a front view of the head 3 viewed from the face surface 2 side, and FIG. 3B is a cross-sectional view taken along the line CC in FIG. 2A. 4A is a cross-sectional view of the head 3 taken along the line AA in FIG. 3A, and FIG. 4B 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. 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 weight member J partially provided on the toe side and the heel side of the head main body h. Although not particularly illustrated, the weight member J and the head main body h are joined by an appropriate method such as fitting press fitting.

  Further, the head 3 has a hollow portion k therein. That is, the head body h of the head 3 exists over the entire head 3 except for the weight member J on the top side and the sole side, and forms most of the top surface 15 and the sole surface 4. However, inside the head 3, as shown in the cross-sectional views of FIGS. 4A and 4B, the face side portion hf that is substantially near the face surface 2 and the back side portion that is substantially near the back side. hb, and a cavity k is provided between the face side portion hf and the back side portion hb. That is, a portion between the substantially opposite top surface 15 and the sole surface 4 and other than the face side portion hf and the back side portion hb is the hollow portion k.

As shown in FIG. 4A, the face-side portion hf and the back-side portion hb are separated in the face-back direction of the head 3, so that a cavity is formed as shown in the side view of FIG. Part of the portion k constitutes a penetrating portion that penetrates from the toe side to the heel side of the head 3.
Further, as shown in FIG. 4A, in the most back side portion of the head 3 (near the back side vertex), the contour shape of the back side portion hb substantially matches the contour shape of the head 3, Except for the vicinity of the apex, the contour shapes do not match, 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. 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. 4A, the structure of the face side portion hf is such that the volume (weight) is concentrated on the toe side portion and the heel side portion, and the center portion in the toe / heel direction is relatively thin. It is plate-shaped. Therefore, as shown in FIGS. 4A and 4B, the cavity k is particularly widely distributed near the center of the head 3 in the toe-heel direction.

  The weight member J is joined to the toe side and the heel side of the face side portion hf. The weight member J itself is a solid member, and is made of a material having a specific gravity greater than that of the head body h (for example, copper, zinc, brass, tungsten, and an alloy mainly composed thereof). 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 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 side surface of the weight member J and the back side described above. It is only the side surface near the back side apex of the portion hb, and the side surface 5 does not exist in other portions (see 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 inside 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.

  As shown in FIG. 1, three axes of the first axis A1 to the third axis A3 are defined for the head 3. 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>M3> M1, and the value of (M3-M1) is 50 (g · cm ² ) or more and 1500 ( g · cm ² ) or less.
Further, the second moment M2 is set to 4000 (g · cm ² ) or more, and the third moment M3 is set to 2500 (g · cm ² ) or more.

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.

Further, since M2>M3> M1, in addition to the rotation of the head around the second axis, the rotation of the head around the first axis is relatively stable compared to the rotation of the head around the third axis. 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. Among such putting strokes, the short putt has a particularly small swing width. Here, short putting means that the distance to the target (cup) is about 3 m or less. In addition to the rotation about the second axis A2 described above, the rotation of the head during the stroke of the short pad becomes relatively large around the first axis A1, but the rotation around the third axis A3 is relatively small. Accordingly, the second moment M2 is maximized and the first moment M1 is minimized among the first moment M1 to the third moment M3, so that the rotation around the second axis A2 and the first axis A1 with relatively large rotation can be performed. It can be stabilized. Therefore, the head trajectory during the stroke is stabilized. The rationale is the tennis racket theorem described later.

Further, since the value of (M3−M1) is 1500 (g · cm ² ) or less, the third moment M3 becomes too large and the M3 becomes larger than the second moment M2, or the M3 and M2 It is suppressed that the difference between and becomes smaller. Therefore, the effect of making the second moment M2 larger than the first moment M1 and the third moment M3 becomes remarkable. Alternatively, it is suppressed that M1 becomes too small and rotates around the first axis so that the hit point position varies in the vertical direction. Furthermore, since the value of (M3−M1) is 50 (g · cm ² ) or more, the effect of M3> M1 is reliably achieved.

The second moment M2 is 4000 (g · cm ² ) or more, and the third moment M3 is 2500 (g · cm ² ) or more.
When the second moment M2 is small, the head 3 is likely to rotate around the second axis A2, the face surface 2 is likely to vary in the left-right direction, the hitting direction is likely to be varied, and the ball is in contact with the face surface 2. Since the angle changes, the hitting point position is also easily displaced. Further, when the third moment M3 is small, head rotation around the third axis A3 is likely to occur, and the hit point position is likely to be displaced in the top / sole direction (vertical direction). However, since M2 and M3 are not less than the above numerical values, this tendency is suppressed.

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 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.

  Further, since the swing width is extremely small in the short putting in the putting stroke, the rotation of the head during the stroke becomes relatively large in addition to the rotation around the second axis A2 described above. However, the rotation around the third axis A3 is relatively small. According to the tennis racket theorem described above, when M2> M3> M1, the rotation about the third axis A3 which is the reference axis of the third moment M3 where the moment of inertia is neither the maximum nor minimum is relatively unstable. However, in the short pad, the rotation around the third axis A3 is relatively small. Therefore, the head trajectory during the short pad stroke is stabilized by preferentially stabilizing the rotation around the second axis A2 and the first axis A1 with relatively large rotation.

  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 short pad, the rotation around the third axis A3 is relatively small. Therefore, the rotation around the second axis A2 and the first axis A1 is prioritized and stabilized over the rotation around the third axis A3. This stabilizes the head trajectory during the stroke.

  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.

In the present invention, preferred ranges in the magnitude relationship between the second moment M2 and the third moment M3 are as follows.
When the second moment M2 is equal to or less than the third moment M3 (M2 ≦ M3), M2 does not become the maximum among the three moments of inertia M1 to M3. In addition, the rotation of the head around the second axis A2 becomes unstable, and the path of the putter tends to vary in the toe-heel direction (left-right direction), particularly during takeback. According to the theory applying the tennis racket theorem described above, even if the second moment M2 is smaller than the third moment M3, the second moment M2 is smaller than the first moment M1 (that is, The rotation around the second axis A2 is stable even when the second moment M2 is minimum). However, in this case, the second moment M2 is small, so that the direction of the face surface is easily changed, and The directionality tends to deteriorate. For this reason, M2> M3 is good, and (M2-M3) is preferably 1490 (g · cm ² ) or more, more preferably 1970 (g · cm ² ) or more.
If (M2-M3) becomes too large, M3 becomes too small and M3 <M1 is likely to occur, head rotation around the third axis A3 is likely to occur, and the hit point position is likely to vary, Production may be difficult. Therefore, (M2-M3) is preferably 4000 (g · cm ² ) or less, and more preferably 3000 (g · cm ² ) or less.

In the present invention, preferred ranges in the magnitude relationship between the second moment M2 and the first moment M1 are as follows.
If the second moment M2 is equal to or less than the first moment M1 (M2 ≦ M1), M2 will not be the maximum among the three moments of inertia M1 to M3. In addition, the rotation of the head around the second axis A2 becomes unstable, and the path of the putter tends to vary in the toe-heel direction (left-right direction), particularly during takeback. When the second moment M2 is minimum, the second moment M2 is small as described above, so that the direction of the face surface is likely to change, and the directionality of the hit ball tends to deteriorate. For these reasons, M2> M1 is good, and (M2−M1) is preferably 1000 (g · cm ² ) or more, more preferably 1500 (g · cm ² ) or more, and further 2100 (g · cm ² ) or more is preferable.
If (M2-M1) is too large, the first moment M1 is too small and the head rotation around the first axis A1 is likely to occur, and the striking point position tends to vary in the vertical direction, or the head is difficult to manufacture. It may become. Therefore, (M2-M3) is preferably 4000 (g · cm ² ) or less, and more preferably 3000 (g · cm ² ) or less.

In the present invention, preferred ranges in the magnitude relationship between the third moment M3 and the first moment M1 are as follows.
When the third moment M3 is smaller than the first moment M1 (M3 <M1), the magnitude relationship of M2>M1> M3 is likely to occur, and therefore the rotation about the first axis A1 is unstable from the tennis racket theorem described above. Thus, the stroke trajectory in the short pad becomes unstable. Therefore, (M3-M1) is 50 (g · cm ² ) or more, preferably 100 (g · cm ² ) or more, and more preferably 160 (g · cm ² ) or more.
On the other hand, if (M3-M1) is too large, the third moment M3 becomes too large and the M3 becomes larger than the second moment M2, or the difference between the M3 and M2 becomes small. The effect of maximizing the two moments M2 may be lost or reduced. Alternatively, M1 may become too small and rotate excessively around the first axis, causing the hit point position to vary in the vertical direction or causing duffing. Therefore, (M3-M1) is set to 1500 (g · cm ² ) or less, more preferably 1350 (g · cm ² ) or less, and further preferably 1300 (g · cm ² ) or less.

If the second moment M2 is too small, it becomes difficult to set the second moment M2 to be larger than the first moment M1 and the third moment M3, or the difference between M2 and M3 (and M1) becomes small. The effect of maximizing M2 is lost or decreased, and the head behavior tends to become unstable. For this reason, the head trajectory during the putting stroke tends to vary. Further, if the second moment M2 is small, head rotation around the second axis A2 is likely to occur, the face surface direction becomes unstable, and the hitting ball direction and the hitting point position vary. Therefore, the second moment M2 is preferably 4000 (g · cm ² ) or more, more preferably 4500 (g · cm ² ) or more, and particularly preferably 4880 (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. Therefore, the first moment M1 is preferably 1000 (g · cm ² ) or more, more preferably 1500 (g · cm ² ) or more, and particularly preferably 2100 (g · cm ² ) or more. If the first moment M1 is too large, the head weight may become too large, or the head shape may be uncomfortable, so 3500 (g · cm ² ) or less is preferable, and 2750 (g · cm ² ) or less is more preferable. 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 2500 (g · cm ² ) or more, and particularly preferably 2900 (g · cm ² ) or more. Become too third the moment M3 is too large head weight is large, because it may discomfort the head shape or cause, preferably 4000 (g · cm ²⁾ or less, still is 3500 (g · cm ²⁾ or less preferable.

  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. Further, when the weight member J is used as in the above-described embodiment, the material of the weight member J can be copper, brass, tungsten, tungsten alloy such as W—Ni, W—Cu, or the like. . Further, when using the weight member J 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 with the weight member J is increased, and the degree of freedom in designing the weight distribution of the head 3 is improved. This is preferable.

(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 was copper, and the material of the head body h was an aluminum alloy.

  Example 1 was the same as the embodiment shown in FIGS. 1 to 4 as in the embodiment described above. The toe / heel direction width Wc of the weight member J provided on the toe side and the heel side is 12 mm. Further, the thickness of the thin portion near the center of the face surface is set to 5 mm for Tf (see FIG. 4A), the thickness Tc of the head body h on the top side of the cavity k is set to 3 mm, and the sole of the cavity k is set. The thickness Ts of the head main body h on the side was set to 3 mm (see FIG. 4B).

The form of Example 2 is shown in FIG.5 and FIG.6. FIG. 5A is a plan view of the second embodiment viewed from the top surface side, and FIG. 5B is a side view of the second embodiment 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.
The structure of the second embodiment is basically the same as the structure of the first embodiment. However, the weight member J is not only attached to the toe side and the heel side of the face side portion hf of the head body h, but also the back side portion hb. This is different from the first embodiment in that the back side weight member Jb is attached to the back side. That is, the back side portion of the back side portion hb in the first embodiment is replaced by the back side weight member Jb. 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 lower surface of the back side weight member Jb is exposed to the sole surface 4 side of the head 3 and constitutes a part of the sole surface 4. The back-side weight member Jb has a maximum width Hc in the top / sole direction (see FIG. 5B) of 20 mm, and a face-back direction width Dc (see FIG. 5A) of 14.5 mm. ing. The width Wc is 7 mm, which is smaller than that of the first embodiment. The wall thicknesses Tf, Tc, and Ts are the same as those in the first embodiment.

The form of the comparative example 1 is shown in FIG.7 and FIG.8. Fig.7 (a) is the top view which looked at the comparative example 1 from the top surface side, FIG.7 (b) is the side view seen 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.
The comparative example 1 has a structure similar to that of the second embodiment, but there is no weight member J on the toe side and heel side of the face side portion hf of the head body h provided in the second embodiment, and the weight member J portion. Is replaced by the face side portion hf. Further, the size of the back side weight member Jb is different from that of the second embodiment, the maximum width Hc in the top / sole direction (see FIG. 7B) is 23 mm, and the face / back direction width Dc (see FIG. 7A). )) Is 22 mm.

The form of the 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 a 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 the comparative example 2 is constituted by an aluminum alloy face plate Fp having the same contour shape as the face surface 2, and on the back side of the face plate Fp, the face plate A thick plate-like head front portion hz having substantially the same shape as 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, this Comparative Example 2 has a hosel 21. 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 and 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 results are shown in Table 1.

The contents of “sensory evaluation” described in Table 1 will be described.
Nine testers made six hits (putting) for each test club, and performed sensory evaluation on the stability of the stroke (hardness of blur). That is, each tester performed a sensory evaluation as to whether or not the stroke was stable for each club. And, when the number of testers who felt that “the stroke was stable” was 8 or more out of 9, ◎, the case of 5-7, ○, and the case of 0-4, x.

Next, the “variation index” shown in Table 1 will be described.
This “variation index” is an index indicating the degree of variation (reproducibility) of the head track with respect to the toe-heel direction (left-right direction) at the time of takeback of the stroke. The “variation index 1” is a variation index in the tester 1, and this test was performed for nine testers 1 to 9.

A method for calculating the variation index will be described.
In calculating this index, each tester performs a putting stroke with a cup 2 m ahead, and the orbit of the putter head at the time of takeback is taken from above with a high-speed camera. That is, the head trajectory projected on the ground is observed by photographing the head trajectory from above. And how much this trajectory is in the left / right direction (perpendicular to the reference direction line on the ground) with respect to a straight line (hereinafter referred to as a reference direction line) connecting the ball position before hitting the ball (hereinafter referred to as ball position) and the cup. ) Is measured backward from the ball position (in the direction opposite to the cup) at a point of 100 mm, a point of 150 mm, and a point of 200 mm. The measurement is performed using an image taken by the high speed camera.

  The trajectory actually obtained in this way is shown in FIG. FIG. 14 shows the measurement results of each club in one of the nine testers. Each curve on the graph of FIG. 14 shows the orbit of the putter head taken from above. The horizontal axis (X axis) passing through the origin (coordinates 0, 0) in the graph indicates the above-described reference direction line, and the origin indicates the above-described ball position (center thereof). The vertical axis (Y-axis) direction of the graph is the left-right direction, and the numerical value of the Y coordinate indicates the deviation (mm) in the left-right direction from the reference direction line, plus is the deviation distance to the left, and minus is the deviation to the right. The deviation distance is indicated. The coordinate on the horizontal axis (X coordinate) indicates the distance from the ball position in the reference direction line direction, and the front of the ball position (cup side) is described as positive and the rear of the ball position (side opposite the cup) is described as negative. Therefore, in this test that measured the trajectory in takeback, the X coordinate is a negative value. Since each club has made six strokes, six orbits are listed for each club.

Then, with respect to each measured trajectory, the trajectory of the trajectory at each of the 100 mm point (that is, X coordinate is −100), 150 mm point (X coordinate is −150), and 200 mm point (X coordinate is −200) from the ball position is measured. Read the deviation in the left-right direction (that is, the numerical value of the Y coordinate). Then, for each of these points, the standard deviation σ of the measurement value (6 data) of the horizontal deviation in the six hits is calculated, and for each club, at the rear 100 mm point, the rear 150 mm point, and the rear 200 mm point The standard deviations σ100, σ150, and σ200 are calculated. These σ100, σ150, and σ200 are averaged to calculate σave of the club. That is, σave = (σ100 + σ150 + σ200) / 3.
Then, σ AVE in each tester is calculated by averaging σ ave in each club. That is, σAVE in a certain tester is
(Σave [Example 1] + σave [Example 2] + σave [Comparative Example 1] + σave [Comparative Example 2]) / 4
Further, by calculating (σave−σAVE) for each club, a variation index for the club in the tester is calculated.

In this way, the variation index is calculated by subtracting the average of the variation degrees of the four clubs from the variation degree of the trajectory of each club for a certain tester. It is an index indicating the degree of the club. The smaller the value (the smaller the value), the smaller the variation of the track. In particular, when the variation index is a negative value, σave of the club is smaller than σAVE, which is the average of the four clubs in each tester.
Comparing the example and the comparative example, in Example 1, there are 7 testers in which the variation index is a negative value, and in Example 2, the tester is also 7 out of 9. On the other hand, negative values are few in Comparative Example 1, which is 2 out of 9 people, and Comparative Example 2 is similarly 3 out of 9 people. As described above, Examples 1 and 2 were superior to Comparative Examples 1 and 2.

  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. 15, 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 is easy to set the weight balance of the putter head to a weight balance where M2>M3> M1 and the value of (M3-M1) is 50 (g · cm ² ) or more and 1500 (g · cm ² ) or less. It is. First, the depth of the center of gravity is preferably 10 mm or more, more preferably 15 to 25 mm. 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, and more preferably 5 mm to 15 mm. The ratio Hw / Hd of the head width Hw to the head depth Hd is preferably 1.1 to 2.8, and more preferably 1.1 to 2. Furthermore, the head height Hh is preferably 20 mm to 35 mm. Furthermore, the head weight is preferably 280 to 400 g, more preferably 320 to 380 g.

It is a perspective view of the putter head with which the golf putter in one embodiment 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 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 sectional drawing in the AA line of Fig.3 (a), (b) is sectional drawing in the BB 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 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 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 figure (graph) which shows the head track in the takeback measured in order to calculate a variation index. It is a perspective view which shows an example of the conventional putter head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Golf putter 2 Face surface 3 Head G Center of gravity M1 1st moment M2 2nd moment M3 3rd moment A1 1st axis A2 2nd axis A3 3rd axis

Claims (9)

Three inertia moments M1, M2 and M3 defined by the following (1) to (3) when placed on a horizontal surface in the reference installation state are:
M2>M3> M1
And satisfy the relational expression
A putter head set to a weight balance where the value of (M3-M1) is 50 (g · cm ² ) or more and 1500 (g · cm ² ) or less ;
The putter head is used for hitting a ball, a top surface constituting the upper surface of the putter head, a sole surface constituting the lower surface of the putter head, a side surface extending between the sole surface and the top surface, and And a face surface that is a plane of
The putter head has a height of 20 to 35 mm, and
The golf putter having a weight of 280 to 400 g .
(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 Wherein M2 is not less 4000 (g · cm ²⁾ or more and golf putter according to the M3 is 2500 (g · cm ²⁾ or more Der Ru請 Motomeko 1. The golf putter according to claim 1 or 2, wherein a ratio of the width of the putter head to the depth of the putter head is 1.1 to 2.8. The golf putter according to claim 1, wherein the putter head has a shaft hole into which a shaft is inserted and joined. The center of gravity depth of the putter head is 10 to 25 mm, the center of gravity height of the putter head is 5 to 20 mm, and the M1 is 1000 to 3500 (g · cm ² ), And (M2-M3) is 1490 to 4000 (g · cm) ² ) And (M2-M1) is 1000 (g · cm) ² The golf putter according to any one of claims 1 to 4. The putter head includes a head main body and a weight member having a specific gravity larger than that of the head main body. The material of the head main body is a single or composite of brass, soft iron, stainless steel, aluminum alloy, titanium, and titanium alloy. The golf putter according to claim 1, wherein the weight member is made of copper, brass, tungsten, or a tungsten alloy. The said putter head has a cavity part in the inside, and a part of this cavity part comprises the penetration part penetrated from the toe side of the said putter head to the heel side. Crab golf putter. The putter head includes a head body and a weight member having a larger specific gravity than the head body,
The putter head has a hollow portion therein,
The head body covers the entire putter head except for the weight member portion on the top side and the sole side,
Inside the putter head, the head body is divided into a face side portion that is substantially close to the face surface and a back side portion that is substantially close to the back side, and between the face side portion and the back side portion. Is provided with the cavity portion,
A portion other than the face side portion and the back side portion between the substantially opposing top surface and the sole surface is the hollow portion, and
The face-side portion and the back-side portion are spaced apart in the face-back direction of the putter head, and a part of the hollow portion constitutes a penetrating portion that penetrates from the toe side to the heel side of the putter head. The golf putter according to any one of 1 to 7. The putter head includes a head body and a weight member having a larger specific gravity than the head body,
The golf putter according to claim 1, wherein the weight member is attached to a toe side, a heel side, and a back side of the head main body.

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