JP2003135632A - Iron-type golf club head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the carry. SOLUTION: The iron-type golf club head 1 has a back face B which is provided with a cavity C dented toward a face surface F. When it is placed on a horizontal surface HP in a standard state at a regular lie angle and a loft angle β, the depth D of center of gravity which is the distance between the head center of gravity G and a sweet spot SS which is the intersecting point between the normal line drawn from the head center of gravity G toward the face surface F and the face surface F is 4.0 mm or more and the sweet spot height H which is the height of the sweet spot SS from the horizontal surface HP is 21.5 mm or less. Furthermore, the moment of inertia of the head around a horizontal axis which passes through the head center of gravity G and is parallel to the face surface F is at least 500 g.cm<2> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron type golf club head useful for reducing variations in flight distance and obtaining stable flight performance.

[0002]

Prior Art and Problems to be Solved by the Invention FIG.
As shown in (A) and its sectional view (A), (B), there is a cavity c in the back face portion b, and the undercut portion d (the sole shown in the figure) is further recessed in the cavity c toward the outer periphery of the head. It shows the one that is dented on the side.)
In the iron type golf club head in which the head is formed, the center of gravity G of the head is located closer to the back face portion b side than a general cavity type head. Therefore, such a head has a large center-of-gravity depth D, which is the distance between the center of gravity G of the head and the sweet spot point SS where the normal line drawn from the center of gravity G of the head to the face surface f intersects the face surface f. Tends to be. The sweet area expands in the head having a large depth of gravity D.

Further, as a result of various experiments conducted by the inventors, when the depth of center of gravity D becomes large like a head having an undercut portion d, the sweet spot point SS is removed as seen in a wood type golf club head. It has also been found that a gear effect occurs when hitting a ball at a position. That is, FIG.
As shown in (A), when the ball is hit on the toe side of the sweet spot point SS, the head rotates around the center of gravity in the clockwise direction in the figure, and a force in the opposite direction is applied to the ball B. Therefore, after being hit to the right of the target flight line L, it is possible to gently return to the direction of the target flight line L by a so-called hook spin in the counterclockwise direction. Further, as shown in FIG. 3B, when the ball is hit on the heel side of the sweet spot point SS, the head rotates counterclockwise around the center of gravity in the figure, and
Since a force in the opposite direction is applied to the ball B, the ball B may be hit slightly to the left of the target flight line L and then slowly return to the target flight line L by a so-called slice spin in the clockwise direction. it can. As described above, the lateral gear effect is preferable in that the variation in the left and right of the hit ball is reduced during a miss shot.

By the way, since the iron type golf club is a club which directly aims at the green, the flight distance stability performance of a hit ball is always emphasized so that the same flight distance can always be obtained no matter how many times it is hit. However, when the above-mentioned gear effect appears in the vertical direction, the backspin amount of the ball changes, which appears in the height difference of the hit ball and the like, and may eventually occur as variations in flight distance. For example, as shown in FIG. 8 (A), when the ball B is hit above the sweet spot point SS, the head rotates counterclockwise around the center of gravity in the figure, and in the opposite case to the hit ball. Since the directional force is applied, generally, the launch angle is high, the backspin amount is reduced, and the flight distance is easily increased. On the other hand, as shown in (B) of the same figure, when the ball is hit below the sweet spot point SS, the head rotates clockwise around the center of gravity in the figure, and the ball is in the opposite direction to the hit ball. Since a force is applied, the launch angle is low, the amount of backspin is increased, and the flight distance is likely to be shortened due to rising.

As described above, in the head provided with the undercut portion d, in order to reduce the variation in the flight distance,
It becomes necessary to suppress the above-mentioned vertical gear effect. In order to reduce the gear effect, the center of gravity depth D may be reduced, but this is not preferable because the sweet area is reduced and the lateral gear effect is lost.

The present invention has been devised in view of the problems peculiar to the iron type golf club head having such a large depth of center of gravity, and basically sets a large moment of inertia about the horizontal axis of the head. As a result, by reducing the vertical gear effect while maintaining the horizontal gear effect, it is an object of the present invention to provide an iron type golf club head that is useful for reducing variations in the flight distance and obtaining a stable flight distance. .

[0007]

According to a first aspect of the present invention, there is provided an iron type golf club head having a cavity in the back face portion which is recessed toward the face surface. 3. In a standard state in which the head is placed on a horizontal plane at a loft angle, the depth of center of gravity D, which is the distance between the center of gravity of the head and the sweet spot point where the normal to the face surface drawn from the center of gravity of the head intersects the face surface, is 4.
The sweet spot height, which is 0 mm or more and the height of the sweet spot from the horizontal plane, is 21.5 mm or less, and the moment of inertia of the head around the horizontal axis passing through the head center of gravity and parallel to the face surface is 500. (G
・ It is characterized by being more than cm ² ).

In the invention according to claim 2, the ratio (Ia / m) between the inertia moment Ia (g · cm ² ) and the head mass m (g) is 2.8 to 3.80 (cm ² ). The iron type golf club head according to claim 1, wherein:

The invention according to claim 3 is the iron type golf club head according to claim 1 or 2, wherein the moment of inertia Ia is 700 to 1000 (g · cm ² ).

The invention according to claim 4 is the iron type golf club head according to any one of claims 1 to 3, wherein the coefficient of restitution is 0.755 to 0.830.

In the present specification, the restitution coefficient is "U.S.G.A. Procedure for Measuring the V".
elocity Ratio of a Club Head for Conformance to Ru
Measurement shall be based on le 4-1e, Revision 2 (February 8, 1999). Specifically, a golf ball is shot by using a ball launching device and is made to collide with a sweet spot on a face portion of a head mounted without being fixed on a pedestal, and an incident velocity Vi and a rebound velocity immediately before the collision of the golf ball. Measure Vo and. Then, when the incident velocity of the golf ball is Vi, the rebound velocity is Vo, the head mass is MH, and the average mass of the golf ball is MB, the restitution coefficient e was calculated by the following formula. (Vo / Vi) = (e.MH-MB) / (MH + MB) The distance from the launch port of the golf ball to the face is 55 inches, and the ball is not more than 5 mm away from the sweet spot of the head. And it is made to collide with the face surface at right angles. The golf ball uses Pinnacle Gold made by Titleist, and the initial ball speed is 160
Feet ± 0.5 feet (48.768 ± 0.152
4 m / s).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing an embodiment of the iron type golf club head of the present invention, and FIG.
3 is a cross-sectional view taken along line A, and FIG. 3 is a rear view of FIG. 1 to 3 show a reference state in which the head is placed on a horizontal plane with a prescribed lie angle α and loft angle β. In the drawings, an iron-type golf club head (hereinafter, also simply referred to as “head”) 1 of the present embodiment has a plate-shaped face member 2 having a face surface F for hitting a ball.
And a head main body 3 having the face member 2 on the front surface thereof.
A cavity C that is recessed toward the face surface F is formed in.

In the present embodiment, the head main body 3 is made of a metal material having a relatively large specific gravity, such as stainless steel (for example, SUS630), and has a top portion 3a as an upper portion of the head and a sole portion 3b as a lower portion of the head. A toe portion 3c connecting the head tip side of the head portion 3c, a neck portion 3d connecting the top portion 3a and the sole portion 3b of the head heel side, and a shaft (not shown) extending upward from the neck portion. It has a shaft mounting portion 3e. In the reference state, the shaft center edge CL of the shaft mounting portion 3e is set to the lie angle α. Further, the head main body portion 3 has an opening portion which is surrounded by the top portion 3a, the toe portion 3c, the sole portion 3b and the neck portion 3d and penetrates in the front and rear direction in this example, and the front peripheral edge thereof is as shown in FIG. An inwardly facing surface 7 facing the outer peripheral end surface 2a of the face member 2,
A face support portion 10 having a stepped shape is formed, which includes a support surface 9 that supports the back surface 2b of the face member 2.

The face member 2 is made of a material different from that of the head body 3, and in this example, the head body 3 is formed.
Metal material having a smaller specific gravity than that of titanium alloy (Ti-
6Al-4V), for example, by caulking, adhering, brazing, to the face attaching portion 10 of the head main body portion 3,
When possible, they are fixed by means such as welding. When the face member 2 is made of a metal material having a specific gravity smaller than that of the head body 3 in this way, the head weight is reduced to the face surface F.
More can be distributed around or behind the. More preferably, it is desirable to set the mass of the face member to about 45 to 55 g by using a material having a high specific strength for the face member 2. The face member 2 may be appropriately provided with a face line groove or the like that enhances the frictional force with the ball.

The thickness t of the face member 2 is not particularly limited, but if it is too large, the resilience performance tends to decrease and the flight distance tends to decrease as a whole. It is not preferable because it deteriorates the sex. From such a viewpoint, the thickness t of the face member 2 is preferably 2.0.
˜3.0 mm, more preferably 2.3 to 2.8 mm.

Further, the head 1 of this example is constructed as a so-called cavity iron in which a cavity C which is recessed toward the face surface F is formed in the back face portion B. Particularly preferably, as shown in FIG. 2, the inner wall portion 11 of the head main body portion 3 surrounding the cavity C is preferably provided with an undercut portion U which is recessed toward the outer peripheral portion of the head. The undercut portion U is formed as a so-called countersinking groove by being provided on the face surface side of the inner wall portion 11. Further, the undercut portion U can transfer the weight of the portion to the rear of the inner wall portion 11 of the cavity C, for example. Specifically, the center of gravity G of the head,
The center of gravity depth D, which is a distance parallel to the normal line between the face spot F drawn from the center of gravity G of the head and the sweet spot point SS intersecting the face face F, is 4.0 mm or more, and more preferably. It is desirable that the thickness is 4.0 to 6.0 mm, more preferably 4.5 to 5.5 mm. The value of the depth D of the center of gravity becomes larger than that of the conventional head.

Therefore, the center of gravity of the head 1 can be located further rearward. The undercut portion U is shown in FIG.
3 to 3, the toe portion 3c is formed only on the sole portion 3b side, as shown in FIGS. 4 (A) and 4 (B).
Alternatively, it may be recessed toward the top portion 3a or may be used in various forms such as being continuously formed in an annular shape on the inner wall portion 11 of the cavity C as shown in FIG. 4 (C).

By setting the depth of the center of gravity D in this manner, it is possible to produce the above-described gear effect despite the iron type head. Therefore, when the hitting point position deviates to the left or right with respect to the sweet spot SS, the above-described lateral gear effect is generated, which helps stabilize the directionality of the hit ball. If the depth of center of gravity D is less than 4.0 mm, it becomes difficult to obtain the effect of enhancing the directional stability of the hit ball due to the gear effect as in the conventional case.

On the other hand, if the depth of center of gravity D exceeds 6.0 mm, it becomes difficult to secure a low center of gravity, and it becomes difficult to hit the ball at the sweet spot point SS. Such a depth of the center of gravity D uses a metal material having a low specific gravity for the face member 2 as in this example, uses a metal material having a high specific gravity for the head body portion 3, and forms an undercut portion U in the cavity portion C. It can be adjusted by changing the size and so on.

In the head 1 of this embodiment, the sweet spot height H, which is the height of the sweet spot point SS from the horizontal plane HP, is set to 21.5 mm or less.
If the height of the sweet spot point SS is larger than 21.5 mm, the sweet spot point SS becomes high, and it becomes difficult to hit the ball at the sweet spot point SS, and the flight distance of the hit ball cannot be stabilized. In addition, even if the sweet spot height H is too small, the ball is not moved to the sweet spot point S.
It becomes difficult to hit with S. From such a viewpoint, the sweet spot height H is preferably 18.0 to 21.5 m.
m, and more preferably 19.0 to 21.0 mm.

By the way, in the head 1 of this embodiment, the depth of the center of gravity D is set to be extremely large as described above, so that even if it is an iron type, a gear effect is likely to occur in the vertical and horizontal directions. The lateral gear effect is preferable for improving the directional stability of the hit ball, but the vertical gear effect is not preferable because it causes variations in the flight distance of the hit ball. Therefore, in the head 1 of the present embodiment, as shown in FIG. 1, the inertial moment of the head around the horizontal axis Ha that passes through the center of gravity G of the head and is parallel to the face surface F (hereinafter, the inertial moment in this direction will be referred to for convenience. It is called the upper and lower moments of inertia.) Ia 500g
By setting it to be not less than cm ² and making it difficult to rotate in the vertical direction, the vertical gear effect can be reduced without impairing the horizontal gear effect.

As a result of various experiments conducted by the inventors, when the vertical inertia moment Ia is less than 500 g · cm ² , the vertical gear effect cannot be sufficiently suppressed in the above-described head having the deep center of gravity depth D. However, there is a tendency that variations in flight distance during miss shots occur easily. On the other hand, if the upper and lower inertia moments Ia are too large, the center of gravity G of the head tends to increase, and it becomes difficult to set the sweet spot height H and the like within the regulation range. From such a viewpoint, the upper and lower inertia moments Ia are 500 to 1000 g ·
It is desirable to set it to be cm ² , more preferably about 700 to 1000 g · cm ² .

The upper and lower moments of inertia Ia (g · c
m ² ), head mass m (g), ratio (Ia / m)
Is about 2.8 to 3.8 (cm ² ) and more preferably 3.0
It is good to set it to about 3.3 (cm ² ). The ratio (Ia /
When m) is less than 2.8 (cm ² ), the upper and lower moments of inertia Ia commensurate with the head mass cannot be obtained, and the effect of suppressing the gear effect in the vertical direction is insufficient, and conversely the ratio (Ia /
When m) exceeds 3.80 (cm ² ), the vertical moment of inertia Ia is significantly increased, and at the same time, the sweet spot height H tends to be larger than 21.5 mm.
It is difficult to hit at the sweet spot point SS, and as a result, the flight distance tends to decrease.

The moment of inertia about a vertical axis passing through the center of gravity G of the head (hereinafter, the moment of inertia in this direction is referred to as left and right moments of inertia) Ib is not particularly limited, but is preferably 2500 to 2500. 3300
g · cm ^2, more preferably 2800~3100g · cm ²
Is desirable. Left and right moment of inertia Ib is 25
If it is less than 200 g · cm ^2, the orientation of the head is changed excessively easy tend not directional stability is obtained of the ball due to the lateral gear effect On the contrary, more than 3300 g · cm ^2. The ratio (Ib / m) of the left and right moments of inertia Ib (g · cm ² ) and head mass m (g) is 10-14.
It is about (cm ² ) and more preferably about 11 to 13 (cm ² ).

The head 1 has a coefficient of restitution of 0.755 to
It is desirable to set it to 0.830, more preferably to the range of 0.770 to 0.820. In order to set the coefficient of restitution to such a value, for example, the thickness t1 of the central portion of the face member 2 is set to about 2.5 to 3.0 mm, and the portion contacting the supporting surface 9 of the head main body portion 3 is used. It is effective that the thickness t2 of the peripheral edge portion including is smaller than t1 and about 2.0 to 2.5 mm. The width of the peripheral portion is, for example, the outer peripheral end surface 2
About 3 to 10 mm is preferable from a. As a result, the natural frequency of the face portion can be reduced to approach that of the golf ball. Therefore, by reducing the energy loss at the time of hitting the ball, the coefficient of restitution of the head can be improved as a result.

When the coefficient of restitution is less than 0.755,
The flight distance tends to decrease as a whole, and on the contrary, if it is more than 0.830, it is preferable in that the flight distance of the hit ball increases, but it is necessary to reduce the thickness of each part of the head, which deteriorates the durability. easy.

In the head of this embodiment, the iron type golf club head is not particularly limited in its count. Therefore,
For example, in the case of an iron type golf club set, the present invention may be applied to all the heads, or may be applied to the heads of at least one club. Preferably, the loft angle β is about 15 to 48 degrees, and the club length is 40.
It is preferably applied to a head mounted on a golf club of about 35 inches. In particular, the smaller the loft angle, the greater the original flight distance, and therefore the greater the variation during miss shots. Therefore, the loft angle β is 16
It is particularly desirable to apply to a low count head having a club length of approximately 27 degrees and a club length of approximately 40 to 37.5 inches.

Next, FIGS. 5 and 6 show an example of a concrete structure of a head which can be designed with such a center of gravity. The face member 2 is Ti-6Al-4V, and the head body 3 is SUS6.
30 is used. Further, as shown in FIG. 5, the face width W is set to about 77 to 83 mm, more preferably about 80 to 82 mm. In addition, the face height h1 on the toe side is set to 55
The face height h2 on the heel side is set to 62 mm and about 32 to 43 mm. The face height h1 on the toe side and the face height h2 on the heel side are respectively measured at the toe side end and the heel side end of the substantial striking area. For this position, for example, the toe of the face groove (score line) is measured. Side edges and heel edges are desirable.

Also, the toe side sole width SW1 is set to 22 to 25.
The sole width SW2 on the heel side is set to about 16 to 21 mm. The sole width SW1 on the toe side and the sole width SW2 on the heel side are the sole widths at the positions where the face heights h1 and h2 are measured.

Further, at the center line passing through the center of the horizontal width W of the substantial striking area of the face surface, the face height h3 is 42 to 48 mm, more preferably 43 to 46.
It is set to about mm. The face height is measured in the vertical direction.

The undercut portion U has a length L (shown in FIG. 3) of 25 along the inner wall portion 11 of the cavity C, for example.
mm or more, more preferably 30 mm or more, further preferably 35 mm or more, and the depth d (shown in FIG. 3) is preferably about 3 to 10 mm. The thickness T of the undercut portion (thickness in the direction perpendicular to the face surface and shown in FIG. 2) is set to 3 to 10 mm, more preferably about 5 to 8 mm. In this example head,
Center of gravity depth D is 5.6 mm, sweet spot height H is 2
It was possible to set 0.0 mm and the moment of inertia Ia as about 800 g · cm ² .

[0032]

EXAMPLES Examples in which the present invention is embodied will be described below. The face member is made of titanium alloy (Ti-6Al
-4V) and stainless steel (SUS6
30) is used to form an iron type golf club head having the basic structure shown in FIGS. 1 to 3 (5 iron with a loft angle of 25 degrees).
Was prototyped based on the specifications of Table 1 and the coefficient of restitution was measured. Also, the same shaft was attached to each head to make an iron type golf club as a prototype, and it was attached to a swing robot manufactured by Golf Lab Co., and the head speed was 34.5 m /
s golf ball (Sumitomo Rubber Industries, Ltd. "HI-BR
Each club was hit with 5 balls, and the backspin amount, launch angle, and total flight distance (carry + run) of the launched ball were measured and evaluated as an average value.

In addition, in order to evaluate the stability of the flight distance, the hit point position is 13 mm, 18 mm and 2 from the lower end surface of the sole portion.
The measurement was carried out at 3 points of 3 mm (values at other positions are relative values with 18 mm as a reference). In addition, in order to confirm the gear effect in the lateral direction, the impact was performed at a position of ± 10 mm in the horizontal direction from the sweet spot point, and the maximum variation in the left and right flight distances was also measured. The test results are shown in Tables 1 and 2.

[0034]

[Table 1]

[0035]

[Table 2]

As a result of the test, it can be confirmed that, compared with the comparative example, the variation of the flight distance with respect to the variation of the hitting point in the vertical direction is small, and the flight distance stability of the example is excellent. Also, it was confirmed that the depth of the center of gravity is large and a lateral gear effect is obtained, and the variation in the directionality on a miss shot is suppressed to a small level.

[0037]

As described above, the iron type golf club head of the present invention has a lateral gear which is limited by limiting the depth of the center of gravity, the height of the sweet spot, the moment of inertia about the horizontal axis, etc. to a certain range. By reducing the vertical gear effect while maintaining the effect, it is possible to reduce variations in the flight distance and obtain stable flight distance performance.

[Brief description of drawings]

FIG. 1 is a front view of a head in a normal state showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA.

FIG. 3 is a rear view of FIG. 1.

FIG. 4A to FIG. 4C are rear views showing another embodiment of the present invention.

5A is a front view of the head, and FIG. 5B is a bottom view thereof.

6A and 6B are a front view and a sectional view of a conventional head.

7A and 7B are diagrams illustrating a gear effect in a lateral direction.

8A and 8B are diagrams illustrating a gear effect in a vertical direction.

[Explanation of symbols]

1 golf club head 2 Face member 3 head body 3a Top section 3b sole part 3c toe part 3d neck 3e Shaft mounting part D depth of center of gravity H sweet spot height

Claims (4)

[Claims] 1. An iron-type golf club head having a back face portion having a cavity recessed toward the face surface, the center of gravity of the head being in a standard state of being placed on a horizontal plane at a specified lie angle and loft angle. The center of gravity depth D, which is the distance from the center of gravity of the head to the sweet spot where the normal to the face surface intersects, is 4.0 mm or more, and the height of the sweet spot point from the horizontal plane is The height H of a certain sweet spot is 21.5 mm or less, and the moment of inertia Ia of the head about a horizontal axis passing through the center of gravity of the head and parallel to the face surface is 500 (g).
・ Iron type golf club head characterized by having a size of at least cm ² . 2. The ratio (Ia / m) of the moment of inertia Ia (g · cm ² ) to the head mass m (g) is 2.8 to 3.8.
The iron type golf club head according to claim 1, wherein the iron type golf club head is 0 (cm ² ). 3. The inertia moment Ia is 700 to 100.
0 claim, characterized in that (g · cm ²⁾ is 1 or 2
The described iron type golf club head. 4. The iron type golf club head according to claim 1, wherein the coefficient of restitution is 0.755 to 0.830.