KR101335089B1 - Golf club head - Google Patents

Abstract

An object of the present invention is to prevent the ball from being greatly reduced in the case of rain or in the case of shots from the rough while preventing the ball from being damaged.

In a golf club head in which a plurality of grooves are formed in a face surface, a rounding having a radius of 0.2 mm or less is formed at an edge of the groove, and the width W (mm) of the groove when measured including the rounding is adjacent to the groove. The width Ws between the grooves (mm), the width Wr (mm) of the grooves and the cross-sectional area S (mm 2) of the grooves when measured by a 30 degree measurement method are W / Ws × 100 ≥ 35 (%), S / (Wr × 0.5) × 100 ≧ 70 (%).

Golf club head, face, spin quantity, sand wedge

Description

GOLF CLUB HEAD {GOLF CLUB HEAD}

The present invention relates to a golf club head, and more particularly to a groove formed in the face surface.

[Documentation information of the prior art]

[Document 1] Japanese Unexamined Patent Publication No. 9-19974

[Document 2] Japanese Unexamined Patent Publication No. 9-70457

[Document 3] Japanese Unexamined Patent Application Publication No. 10-179824

[Document 4] Japanese Unexamined Patent Publication No. 2003-93560

[Document 5] Japanese Unexamined Patent Publication No. 2005-287534

[Document 6] Japanese Patent No. 3463779

On the face of the golf club, a plurality of grooves called marking lines, score lines or face line grooves are formed. This groove affects the spin amount of the ball. In the case of iron-type golf club heads, especially wedges, this groove is preferably formed so that the spin amount of the ball is increased.

Document 1 discloses a golf club having a V-shaped or trapezoidal cross section. Documents 2 and 3 disclose golf club heads rounded at the edges of the grooves (the boundary between the side and face surfaces of the grooves). This rounding has the effect of preventing the ball from being damaged (such as grime). Documents 4 and 5 disclose golf club heads that are formed of two surfaces having different angles without making the side of the groove a single surface. Document 6 discloses a set of iron golf clubs in which the ratio of the area of the groove to the face is set differently according to the number of clubs. In addition, there is a rule constraint on the width or depth of the grooves and the pitch between the grooves in the golf club head for the official game, and in consideration of the use in the official game, the design in the range satisfying such a rule is necessary. .

Here, the amount of spin of the ball tends to be reduced in the case of the shot from the rainy weather or the rough, as compared with the shot from the clear sky or the fairway. As a measure for suppressing the reduction of the spin amount of the ball, it is possible to reduce the angle of the edge of the groove. However, if the angle of the edge of the groove is made small, the ball is likely to be damaged. Rounding the edges of the grooves, such as the golf club heads disclosed in Documents 2 and 3, can reduce damage to the ball, but also reduces the spin amount of the ball.

The present invention has been made to solve the above-mentioned conventional problems.

According to the present invention, in a golf club head in which a plurality of grooves are formed in a face surface, a rounding having a radius of 0.2 mm or less is formed at an edge of the groove, and the width W of the groove when measured including the rounding is measured. ) (Mm), width (Ws) between the adjacent grooves (mm), width (Wr) (mm) of the grooves and the cross-sectional area (S) (mm2) of the grooves as measured by a 30 degree measurement method A golf club head is provided, characterized in that: W / Ws × 100 ≧ 35 (%), S / (Wr × 0.5) × 100 ≧ 70 (%).

In this golf club head, a rounding having a radius of 0.2 mm or less is formed at the corners of the groove to reduce the damage to the ball. On the other hand, said "W / Ws x 100" used as an index of the area ratio of the said groove in the said face surface, and said "S / (Wr x 0.5) x 100 used as an index of the magnitude | size of the groove | channel. By setting "to the above numerical value, it is possible to prevent the spin amount of the ball from being greatly reduced in the case of rainy shots or shots from the rough by the balance between the area ratio of the grooves and the size of the volume.

As described above, according to the present invention, the spin amount of the ball can be prevented from being greatly reduced in the case of a rainy shot or a shot from the rough while preventing the ball from being damaged.

1A is an external view of a golf club head 1 according to an embodiment of the present invention. 1A shows an example in which the present invention is applied to an iron golf club head. The present invention is suitable for a golf club head where a large amount of spin of the ball is required, and is particularly suitable for wedges such as sand wedges, pitching wedges and approach wedges. However, the present invention can also be applied to wood or utility golf club heads.

The golf club head 1 has a plurality of grooves 20 formed in its face surface 10. In the case of this embodiment, each groove 20 is a straight groove extending in the toe-heel direction, and an arrangement interval (pitch) of each groove 20 is an equal interval (equal pitch). FIG. 1B is a cross-sectional view of the groove 20 in a direction orthogonal to its longitudinal direction (toe-heel direction) and shows two adjacent grooves 20. In this embodiment, the cross-sectional shape of the groove | channel 20 is the same except for the both ends of the longitudinal direction. In addition, the cross-sectional shape of each groove | channel 20 is the same.

The groove 20 is formed by the pair of side surfaces 21 and 22 and the bottom surface 23, and the cross-sectional shape is trapezoidal. In the case of this embodiment, the cross-sectional shape of the groove | channel 20 is symmetrical with respect to the center line CL. The pair of side surfaces 21 and 22 of the groove 20 are flat surfaces (cross section is straight), respectively, with the upper end continuing on the face surface 10 and the lower end continuing on the bottom surface 23. The angle θ means an angle formed between the side surface 21 and the side surface 22. Bottom surface 23 is parallel to face surface 10. In this embodiment, the cross-sectional shape of the groove 20 is trapezoidal, but may be rectangular, square, or triangular.

The corners 24 of the grooves 20 are rounded. The radius of the rounding of the corners 24 is 0.2 mm or less. This rounding has the effect of preventing the ball from being damaged (such as grime). It is preferable that the radius of rounding is 0.05 (mm) or more and 0.1 (mm) or less.

Each groove 20 has a bottom surface width Wb, a depth D, and a width W. In addition, the width Ws is set between the adjacent grooves 20. Bottom width Wb means the distance between the two ends of the bottom surface 23. In addition, the depth D means the distance from the face surface 10 to the bottom surface 23. The width W is the width of the direction orthogonal to the longitudinal direction of the groove 20. The width W means the width when measured including the rounding (radius r) of the corner 24 of the groove 20, as shown in Fig. 2A, and the rounding starts. It is assumed that the width W is measured from the point (dashed line position in Fig. 2A). In addition, the width Ws means the distance between the point where the rounding of two adjacent grooves 20 starts (broken line position of Fig.2 (a)).

In this specification, when it is "the width | variety of the groove | channel when it is measured including rounding", it means the width | variety (W) by the said measuring method, and so-called 30 which is a measuring method of the width | variety of the groove | channel of a golf club head for a competition. It is distinguished from the width by a degree measuring method (R & A rule internal regulations "30 degree measuring method"). The 30-degree measuring method is a point where the imaginary line L having a 30 degree inclination with respect to the face surface 10 is in contact with the side surfaces 21 and 22 of the groove 20, as shown in Fig. 2C. The gap is measured as the width Wr of the groove 20. Hereinafter, the width at the time of measuring by this 30 degree measurement method is called width on a rule. When rounding is applied to the edge 24 of the groove 20 as in the present embodiment, the width W of the groove 20 may be different from the width Wr on the rule. In addition, when the edge of the groove 20 is not rounded, the width W of the groove 20 coincides with the width Wr on the rule.

In addition, it is determined that the width Wr on a rule is 0.9 (mm) or less. In addition, on the rule, the depth D of the groove is 0.5 (mm) or less. In addition, the pitch of the grooves (distance between the center lines CL of the grooves) on the rule is "width on the rule" (Wr: mm) x 4 or more.

Next, the larger the volume of the groove 20 is, the larger the cross-sectional area of the groove 20 is. As an index which evaluates the magnitude | size of the cross-sectional area of the groove | channel 20, in other words, the volume of the groove | channel 20, in this embodiment, the cross-sectional area ratio mentioned below is proposed. As described above, on the rule of the golf club head for competition, the depth D is 0.5 (mm) or less. Accordingly, the maximum cross-sectional area of the groove 20 in the case where there is no rounding at the corner of the groove 20 and the width Wr on the rule of the groove 20 is as shown on the right side of Fig. 2 (b). Similarly, Wr (mm) x 0.5 (mm) = 0.5 Wr (mm <2>).

Therefore, the cross-sectional area ratio of the cross-sectional area S of the groove 20 (mm 2: the left side in FIG. 2B) to this maximum cross-sectional area is an index for evaluating the size of the volume of the groove 20. The cross-sectional area ratio is shown in the following equation.

[Equation 1]

Cross sectional area ratio (%) = S / (Wr × 0.5) × 100

Next, the area ratio of the grooves 20 in the face surface 10 affects the spin amount of the ball. In this embodiment, the groove area ratio derived from the following formula 2 is proposed as an index of the area ratio of the groove 20.

[Formula 2]

Groove area ratio (%) = W / Ws × 100

In the golf club head 1 of this embodiment, since the rounding of 0.2 mm or less of radius is formed in the edge 24 of the groove | channel 20, damage to a ball is reduced. On the other hand, by the balance between the groove area ratio of the groove 20 defined by Equation 2 and the cross-sectional area ratio of the groove 20 defined by Equation 1, the amount of spin of the ball in the case of a rainy shot or a shot from the rough It can prevent that it is greatly reduced. In this embodiment, the said groove area ratio of the groove | channel 20 shall be 35% or more, and the said cross-sectional area ratio of the groove | channel 20 shall be 70% or more.

(Example)

Fig. 3 shows the first to fifth embodiments of the present invention and the first to seventh comparative examples of the prior art, and shows the results of experiments in which the degree of damage (abrasion degree) and the spin amount of the ball were measured by changing the specification of the grooves. The experiment was performed by forming grooves with different specifications in a sand wedge having a loft angle of 56 degrees and hitting an unused ball with a robot machine. The sand wedge head speed is 40 m / s. In addition, assuming that the shot is in the clear and the rain and the shot from the rough, the ball face is dry (dry) and the ball face is covered with thin paper moistened with water (wet). It was to beat.

In FIG. 3, "specification of a groove" shows the specification of each groove of a comparative example and an Example. In any of the comparative examples and examples, the cross-sectional shape of the grooves is trapezoidal as shown in Fig. 1B. "Angle (theta)" is an angle (angle (theta) of FIG. 1 (b)) between the side surfaces of a groove | channel. The radius of rounding is the radius of rounding on the edge of the groove. The first to third comparative examples do not have rounding at the edges of the grooves. The "groove width W" is the width of the groove in the case of including the rounding as described with reference to Fig. 2A, and the "groove width Wr on the rule" is measured by the 30 degree measurement method. The width of the groove in the case.

"Width between grooves" is the width Ws described with reference to Fig. 2A. "Pitch" is the distance between the centerline of the groove (centerline CL in Fig. 1B). "Groove area ratio" is the groove area ratio calculated by the above expression (2). Depth D is the distance from the face face to the bottom face of the groove. "Section area S" is a cross-sectional area of a groove. "Cross-sectional area ratio" is the said cross-sectional area ratio computed by said formula (1).

Next, in the "experimental result", when "face level" is dry, three evaluators visually observe the rough state of the ball surface after a shot by visual confirmation and a touch, and evaluated in 10 steps. In this experiment, the thing with the roughest surface of the ball was 10, and the one with the least roughness was 1. The "spin amount" is obtained by attaching a mark to the surface of the ball in advance, capturing the ball at impact with a video camera, and calculating the change in the position of the mark. Average of 10 shots for dry and wet.

"Rule fit" indicates whether the golf club heads of the first to seventh comparative examples and the first to fifth embodiments are suitable for the rules of the golf club head for competition. Only the third comparative example is not suitable for the rule in terms of the pitch of the grooves.

Fig. 4A shows a bar graph of the degree of grind among the experimental results shown in Fig. 3. Fig. 4B is a graph obtained by dividing the experimental results shown in Fig. 3 into dry and wet in relation to "groove area ratio"-"spin amount". Fig. 4 (c) is a graph obtained by dividing the experimental results of Fig. 3 into dry and wet in the relation of "cross-sectional area ratio" to "spin amount".

In terms of "abrasion degree," the first to third comparative examples having a small angle θ and no rounding at the corners of the grooves have a large amount of burr. Therefore, rounding the edge of the groove is effective because it prevents the ball from being damaged.

As for the "spin amount", the second comparative example and the third comparative example have a large amount of spin even in wet time, and in particular, in the third comparative example, the spin amount in wet time exceeds the spin amount in dry time. However, as for the 2nd comparative example and the 3rd comparative example, since the "duty degree" is bad as mentioned above, practicality is bad.

Although the "cross-sectional area ratio" is comparatively large (all 70% or more) in the 1st comparative example and the 4th comparative example, the fall of the spin amount at the time of dry and wet is large. This is considered to be due to the small "groove area ratio" (10%, 25%, respectively). In the first embodiment, the "groove area ratio" is the smallest (38%) among the first to fifth embodiments, but the decrease in the amount of spin during wet is small compared with the first and fourth comparative examples.

In the fifth to seventh comparative examples, the "groove area ratio" is relatively large, but the drop in the spin amount between dry and wet is large. This is considered to be attributable to the small "cross-sectional area ratio" (59%, 63%, 50%, respectively). In the third and fifth embodiments, the "cross-sectional ratio" is the smallest (70%) among the first to fifth examples, but the decrease in the amount of spin during wet is small as compared with the fifth to seventh comparative examples.

Based on the above experimental results, it can be seen that the amount of spin during wet can be improved by balancing the "groove area ratio" and the "cross-sectional area ratio". When the "groove area ratio" and "cross-sectional area ratio" of the first to fifth embodiments are set, the "groove area ratio" is set to 35% or more, and the "cross-sectional area ratio" is set to 70% or more. It can be said that a small golf club can be obtained.

In addition, when using the golf club head of this invention for competition, the groove width Wr on a rule needs to be 0.9 (mm) or less. However, excessively narrowing the groove width Wr on the rule also results in a narrow cross-sectional area of the groove. In the third embodiment, the groove width Wr on the rule is 0.6 (mm), but the amount of spin during wet is not significantly lowered compared with the other first, second, fourth and fifth embodiments. Therefore, it is preferable that the groove width Wr on the rule of the groove of the golf club head of the present invention is 0.6 (mm) or more and 0.9 (mm) or less.

1A is an external view of a golf club head 1 according to an embodiment of the present invention, and FIG. 1B is a sectional view of the groove 20. FIG.

2 (a) is an explanatory diagram in the case of providing a rounding at the corner of the groove 20, FIG. 2 (b) is an explanatory diagram of the cross sectional area ratio, and FIG. 2 (c) is an explanatory diagram of the 30 degree measurement method.

3 is a diagram showing experimental conditions and experimental results of an embodiment of the present invention and a comparative example.

4 (a) to 4 (c) are diagrams showing experimental results of Examples of the present invention and Comparative Examples.

<Explanation of symbols for the main parts of the drawings>

1: golf club head

10: face side

20: home

21, 22: side

24: corner of the groove

Claims (2)

In the golf club head formed with a plurality of grooves in the face surface, The groove has a pair of side surfaces and a bottom surface, the cross-sectional shape of which is a trapezoid having a wide width at the face surface side; Rounding with a radius of 0.2 mm or less is formed at the corners of the groove, By the depth D of the groove (mm), the width W of the groove (mm) in the case of including the rounding, the width Ws between the adjacent grooves (mm), 30 degrees The width Wr (mm) of the groove in the case of measurement and the cross-sectional area S of the groove (mm 2), D ≤ 0.5, Wr ≤ 0.9, Ws + W ≥ Wr × 4, W / Ws × 100 ≥ 35 (%), S / (Wr × 0.5) × 100 ≥ 70 (%) Golf club head, characterized in that to satisfy. The golf club head according to claim 1, wherein the width Wr is 0.6 mm or more and 0.9 mm or less.

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