JPH05177018A - Golf club head - Google Patents

Abstract

PURPOSE:To improve the directivity of a driven ball by making the curvature at the high-speed point on the face surface larger than the curvature at the low-speed point so that the flight direction is not drifted horizontally or vertically when the ball is driven at any point on the face surface. CONSTITUTION:In a golf club head 1 formed with the face 2 surface into a protruded curved surface, the angle theta at the point satisfying V1>V is set larger than the angle theta at the point satisfying V1<V, where V is the speed of the sweet spot S when a ball is driven, V1 is the speed of an optional point T on the face 2 surface other than the sweet spot S when the ball is driven, and thetais the angle between the normal line at the sweet spot S and the normal line at the optional point. The spin of the ball 3 driven by a high-speed face surface portion F is increased by a large gear effect, however the correcting effect of the flight direction of the ball 3 after it is driven is increased because the curvature of the portion F is large, and the directivity is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf club head having a face surface formed into a convex curved surface.

When hitting a ball with a golf club head, if the ball is hit at a position outside the sweet spot on the face surface, the directionality of the ball after hitting is reduced. In order to suppress such a problem, conventionally, the face surface of the golf club head is formed into a convex curved surface.

This point will be described in some detail for the understanding of the present invention. FIG. 8 shows a wood type head which is an example of a golf club head, and a sweet spot S is an intersection of a perpendicular line drawn from the center of gravity G of the head 1 to the face surface 2 which is a hitting surface and the face surface 2. It is assumed that the golf club head 1 shown in FIG. 8 has a face surface 2 formed flat.

Now, let us consider a situation where a golf club is swung and a ball is hit. First, when the ball hits the sweet spot S, the ball after the hit flies in a straight line as shown by a straight line A, and good directionality is obtained.

On the other hand, when the ball 3 is hit at the point B on the heel portion 4 side of the sweet spot S, the impact causes the golf club head 1 to rotate around the center of gravity G in the direction indicated by the arrow C. Therefore, due to the so-called gear effect, the ball 3 spins in the direction indicated by the arrow D, and the ball 3 after hitting flies while drawing a curve as exaggerated by the curve E, and its directionality decreases.

On the contrary, the toe part 5 is more than the sweet spot S.
When the ball 3 is hit at a point F on the side of, the club head 1 rotates around its center of gravity G in the direction indicated by the arrow H, so that the ball 3 spins in the direction indicated by the arrow I due to the gear effect, The flight direction bends as shown by exaggerated curve J, and its directionality also deteriorates.

When the ball hits a point on the top portion side of the sweet spot S or a point on the sole surface side of the sweet spot S, the directionality of the ball decreases for the same reason.

Therefore, as shown in FIG. 9, a golf club head 1 in which the face surface 2 is formed into a convex curved surface is used. According to such a club head 1, when the ball 3 is hit at the points B and F on the heel portion or toe side, the ball 3 receives a hitting force in the normal direction of the points B and F. The flight direction of, for example, arrow e,
It is corrected as shown by exaggerating with j, and its directionality is enhanced.

That is, since the face surface 2 is formed into a curved surface, the normal lines of the points B and F on the face surface 2 other than the sweet spot S are in the heel portion 4 with respect to the normal line of the sweet spot S. The ball 3, which is inclined toward the side or the toe portion 5 and hits these points B and F, receives a striking force in its normal direction and tries to fly in this direction. On the other hand, the ball 3 hitting these points B and F has the arrow D, as described above.
Since it spins in the I direction, it tries to fly in the directions shown by the curves E and J (FIG. 8) that are inclined in the opposite direction to the normal line of these points B and F. After all, these two effects cancel each other out, and the ball 3 is closer to the straight line than the curves E and J in FIG.
It flies in the directions of arrows e and j shown in FIG. As described above, the curved surface of the face surface 2 serves to correct the flight direction of the ball 3, and the larger the curvature is, the stronger the correction effect is.

FIG. 9 shows a curved surface in the horizontal plane of the face surface 2. The curved surface in this direction is generally called a bulge.

On the other hand, FIG. 10 shows a curved surface in the vertical plane of the face surface 2, which is generally called a roll. Also in this case, when the ball hits the point on the top portion 6 side or the sole surface 7 side with respect to the sweet spot S, the directionality of the ball is enhanced for the same reason as described above. However, when the ball hits a point on the side of the top portion 6 and when it hits a point on the side of the sole surface 7, the spin direction of the ball is the same direction.

In the conventional golf club head, the curvature of the face surface is set to a constant value both on the bulge and on the roll, and the curvature is constant at any point on the face surface. That is, each of the bulge radius R and the roll radius r shown in FIGS. 9 and 10 was constant over the entire face surface.

[0013]

As described above, conventionally, the face surface of a golf club head is formed into a convex curved surface, and the directionality of the ball when hit with the point where the sweet spot is removed is improved. However, according to a study made by the present inventor, the effect of improving the directionality of the ball is limited and the highly accurate directionality cannot be ensured only with such a conventional configuration. It turned out to be difficult.

It is an object of the present invention to provide a golf club head capable of further increasing the directionality of a ball after hitting, as compared with the prior art.

[0015]

In order to achieve the invention described above, the present invention is directed to a golf club head having a convexly curved face surface, in which the velocity of the sweet spot during hitting is V, and the face surface other than the sweet spot is V. Let V1 be the velocity at the time of hitting an arbitrary point above, and θ be the angle between the normal line at the sweet spot and the normal line at the arbitrary point, and the angle θ of the point satisfying V1> V is V1 <V We propose a golf club head that is set larger than the angle θ of the point that satisfies the condition.

To achieve the above object, in a golf club head having a convex curved surface, the axis line perpendicular to the ground at the time of hitting the ball and passing through the sweet spot is the x axis, and is orthogonal to the x axis. The axis extending from the toe side to the heel side while passing through the sweet spot is defined as the y-axis, and the sole surface side and the toe section are included in the four areas of the face surface divided by the x-axis and the y-axis. Side area is the first area, the top side and toe side area is the second area, the sole side and heel side area is the third area, and the top side and heel side area is the third area. In addition to 4 areas, the angle between the normal line of the center of the first area and the normal line of the sweet spot is θ.
1, the angle between the normal line of the central point of the second area and the normal line of the sweet spot is θ2, and the angle between the normal line of the central point of the third area and the normal line of the sweet spot is θ
3, θ1>θ2>, where θ4 is the angle formed by the normal line of the central point of the fourth area and the normal line of the sweet spot
A golf club head in which each angle is set so as to satisfy θ3> θ4 is proposed.

In order to achieve the same object, in a golf club head having a face surface formed into a convex curved surface, an axis line perpendicular to the ground at the time of hitting the ball and passing through the sweet spot is the x axis, and is orthogonal to the x axis. The axis extending from the toe side to the heel side while passing through the sweet spot is defined as the y-axis, and the sole surface side and the toe section are included in the four areas of the face surface divided by the x-axis and the y-axis. Side area is the first area, the top side and toe side area is the second area, the sole side and heel side area is the third area, and the top side and heel side area is the third area. 4 areas, the average curvature of the curved surface of the first area is C1, the average curvature of the curved surface of the second area is C2, the third
When the average curvature of the curved surface of the area is C3 and the average curvature of the curved surface of the fourth area is C4, a golf club head in which each curvature is set so as to satisfy C1>C2>C3> C4 is proposed.

Further, in a golf club head having a face surface formed into a convex curved surface, when the axis line perpendicular to the ground at the time of hitting the ball and passing through the sweet spot is taken as the x axis, the toe portion is the boundary of the x axis. We propose a golf club head in which the curvature of the curved surface of the face surface located on the side is set larger than the curvature of the curved surface of the face surface located on the heel side.

Further, in a golf club head having a face surface formed into a convex curved surface, an axis line perpendicular to the ground at the time of hitting the ball and passing through the sweet spot is the x axis.
When the axis line that is orthogonal to the axis and that passes through the sweet spot and extends from the toe side to the heel side is the y-axis, the y
A golf club head is proposed in which the curvature of the curved surface of the face surface located on the sole surface side with respect to the axis is set to be larger than the curvature of the curved surface of the face surface located on the top portion side.

At this time, it is desirable to set the curvatures of the face surface portion near the top portion and the face surface portion near the sole surface to be smaller than the curvature of the curved surface of the face surface portion between both portions. ..

Also, a face surface portion near the top portion,
It is advantageous that the face surface portion near the sole surface is formed flat.

[0022]

Embodiments of the present invention will be described in detail below along with its principle.

First, it will be clarified because it is difficult to improve the directionality of a ball after hitting with high accuracy by a conventional golf club head.

The present inventor has studied in detail the behavior of the face surface when the golf club is swung to hit the ball in order to clarify the problems of the conventional golf club head. As a result, it was possible to clarify the novel fact that the velocities of the points on the face surface at the time of hitting the balls were different from each other, and the velocities peculiar to the points were shown. This can be thought of as follows.

FIG. 1 is a view showing a state in which a wood type golf club is swung. At this time, the golf club head 1 first forms an arc K around the grip 9 on the base end side of the shaft 8. Draw and exercise. At the same time, immediately before hitting the ball 3, the player rotates the shaft 8 around its axis as indicated by the arrow L in an attempt to align the face surface 2 of the head 1 with the ball 3 at a right angle, so that the head 1 moves along this axis. Rotate around. That is, the golf club head 1 performs a synthetic motion of the above two motions when hitting the ball.

Now, considering the arcuate motion of the golf club head 1 around the grip, the speed of each part of the head 1 due to this motion is higher in the part far from the grip 9 than in the part close to the grip 9. Become. For example, the velocity distribution of the face surface 2 passing through the sweet spot S of the golf club head 1 as shown in FIG. 2 and along the line N parallel to the axis M of the shaft 8 is from the grip (FIG. 1) as indicated by O. The farther it gets, the bigger it becomes.

On the other hand, due to the rotational movement of the golf club head 1 about the shaft axis M, the speed of the head portion distant from the axis M becomes higher than that of the portion closer to the axis. For example, the velocity distribution of the face surface 2 passing through the sweet spot S as shown in FIG. 2 and along the line P orthogonal to the axis M of the shaft 8 increases as the distance from the axis M increases as indicated by Q.

FIG. 3 shows the velocity distribution of the face surface 2 due to the circular arc movement around the grip of the golf club head 1.
Shows the velocity distribution of the face surface 2 due to the rotational movement of the head 1 around the axis of the shaft 8.

Each point on the face surface 2 when hitting a ball is equal to the above-mentioned 2 points.
It moves at a speed that combines the velocities of the two movements. Therefore, the velocities of the points on the face surface 2 are not all equal, and the velocities peculiar to the points are shown.

However, the conventional golf club head is
As described above, the curvature of the face surface is set to be constant over the entire surface. That is, the curvature of the face surface was set to be uniform and uniform without giving any consideration to the difference in speed between the points on the face surface when hitting a ball. This is the biggest reason why the directionality of the ball cannot be enhanced with high accuracy.

As will be described later in detail, the toe portion at the time of hitting moves at a higher speed than the heel portion. However, when the ball hits such a high-speed toe portion, the ball is greatly affected by the gear effect. The spin becomes remarkable. On the other hand, if the ball hits the slow heel, the ball will have less spin. At this time, as in the conventional golf club head 1 shown in FIG. 9, if the curvature of the face surface 2 is constant, the effect of correcting the flight direction of the ball becomes constant, so that the ball 3 hitting the toe portion 5 becomes constant. The amount of deflection of the ball 3 hitting the heel portion 4 in the flight direction is significantly different. That is, since the ball 3 hitting the point F in FIG. 9 spins strongly, the flight direction of the ball 3 cannot be corrected by the curvature of the point F, while the ball 3 hitting the point B has a degree of its spin. Therefore, the effect of correcting the flight direction of the ball due to the curvature of the point B is too strong, and in any case, the flight direction of the ball 3 deviates from the straight line. In other words, in the golf club head 1 shown in FIG. 9, if the curvature of the face surface 2 is set so as to enhance the directionality of the ball 3 hitting the heel portion 4 side, it hits the toe portion 5 side. When the curvature of the face surface 2 is set so that the directionality of the ball 3 is significantly reduced, and conversely the directionality of the ball 3 hitting the toe portion 5 side is increased,
This time, the directionality of the ball 3 hitting the side of the heel 4 is greatly reduced. This is true for all but the sweet spot S.

The present invention has been made on the basis of such a novel recognition. Taking into consideration the speed at the time of hitting each point on the face surface, a large curvature is set for a large part of the speed. The effect of correcting the flight direction of the ball is strengthened, and conversely, for the portion of low speed, the curvature is set to be small to weaken the effect of correcting the flight direction of the ball, so that when the ball hits any point on the face surface, The basic idea is that the directionality is enhanced.

FIG. 5 is an explanatory view of an embodiment of the present invention in which a face surface 2 of a golf club head 1 having a convex curved surface is enlarged. Here, when a golf club is swung to hit a ball (not shown), its head 1 moves from left to right in FIG.
The speed of the sweet spot S at the time of hitting the ball is V, and the speed at the time of hitting an arbitrary point T on the face surface 2 other than the sweet spot S is V1. Further, the angle formed by the normal line of the sweet spot S and the normal line of the arbitrary point T is θ. If the moving direction of the sweet spot S, that is, the direction of the velocity V is orthogonal to the face surface 2 and the direction of the velocity V of another arbitrary point T is parallel to the direction of the velocity of the sweet spot S, it is arbitrary. Speed V1 at point T and speed V1 in the normal direction
The angle formed by the component V2 of the above becomes the above-mentioned angle θ.

Here, of the arbitrary points T on the face 2 other than the sweet spot S, the angle θ of the point satisfying V1> V is set larger than the angle θ of the point satisfying V1 <V. That is, with reference to the speed V of the sweet spot S, the angle θ of the point having a speed higher than the speed V of this point is
The curvature of each point is set so as to be larger than the angle θ of the point having a velocity smaller than V.

If the curvature of each point on the entire face surface is determined in this way, the spin of the ball 3 hitting the high-speed face surface portion F becomes remarkable due to the large gear effect as shown in FIG. Since the curvature of the part F is large, the correction effect on the flight direction of the ball after hitting is strengthened,
The ball 3 flies in a substantially straight direction, and its directionality is enhanced. On the other hand, the ball 3 hitting the face surface portion B having a low speed has a small spin, but the curvature of the portion B is reduced accordingly, so that the correction effect in the flight direction of the ball is weakened, and in this case, eventually. Also, the ball 3 flies in a substantially straight direction, and its directionality is enhanced.

In other words, the ball 3 hitting the high speed portion of the face surface 2 tends to change its flight direction from a straight state to a large extent due to its remarkable spin, but the high speed portion of the face surface hit by the ball 3 has a curvature. Because it is big, the flight direction is strongly modified and it flies in a straight line. On the other hand, the ball 3 hitting the low-speed portion of the face surface 2 has a small degree of spin, and the flight direction is originally less likely to deviate from the straight state. By reducing the curvature of the low-speed portion of the face surface hit by the sand to weaken the sand by the correction of the flight direction of the ball, the ball 3 is caused to fly in a straight line.

In this way, the directionality of the ball can be effectively enhanced no matter where the ball hits the face surface.

By the way, in order to form the face surface 2 as described above, the velocities of a number of points on the face surface 2 at the time of hitting a ball are measured, and the angle θ, that is, the curvature is correspondingly made to satisfy the above-mentioned condition. The angle θ or the curvature can be set correctly as the number of the actual measurement points increases. However, when such a design method is actually adopted, it is necessary to measure the velocities of a large number of points on the face surface of each golf club, which requires a great deal of labor and increases the cost of the club head. To do.

Therefore, when the golf club head is constructed as follows, the design thereof is facilitated and the cost can be reduced.

FIG. 7 is a front view of the golf club head 1 in which the face surface 2 is formed into a convex curved surface. The face surface 2 of the head 1 is disassembled into four areas. That is, an axis line that is perpendicular to the ground at the time of hitting the ball and that passes through the sweet spot S is the x axis, is orthogonal to this x axis, passes through the sweet spot S, and extends from the toe portion 5 side to the heel portion 4 side. The axis line is the y-axis, and the face surface 2 is divided into four areas by the x-axis and the y-axis. Here, of these four areas, the area on the sole surface 7 side and the toe portion 5 side is the first area I, and the area on the top portion 6 side and the toe portion 5 side is the second area I. Area I
I, the area on the sole surface 7 side and the heel portion 4 side is the third area III, and the area on the top portion 6 side and the heel portion 4 side is the fourth area IV.

According to a study made by the present inventor, although the speeds at the respective points on the face surface 2 are different,
It is known that there is a rough regularity in the magnitude of the speed. That is, the speed of the above-mentioned first area I is the highest, the speed of the second area II is the next, and the speed of this is the third area III.
The speed of Area IV is the slowest. In this way, the speed of the face surface 2 can be grasped in a large amount of 4 minutes. Therefore, paying attention to the center point of each area,
The angles θ described above at the respective points are θ1 and θ, respectively.
2, θ3 and θ4. That is, the angle between the normal line of the point U1 at the center of the first area I and the normal line of the sweet spot S is θ1, and the normal line of the point U2 at the center of the second area II and the normal line of the sweet spot S. The angle formed by θ2, the third
The angle between the normal line of the point U3 at the center of the area III and the normal line of the sweet spot S is θ3, and the angle between the normal line of the point U4 at the center of the fourth area IV and the normal line of the sweet spot S is It is set to θ4. Then, the relationship between these angles is set to θ1>θ2>θ3> θ4. That is,
The angle θ is increased as the speed increases. By doing so, the directionality of the ball after hitting can be enhanced for the above-mentioned reasons, and furthermore, the golf club head 1 can be easily designed and the cost thereof can be reduced.

Similarly, the average curvature of the curved surface of the first area I is C1, the average curvature of the curved surface of the second area II is C2, and the third curvature is the third curvature.
When the average curvature of the curved surface of the area III is C3 and the average curvature of the curved surface of the fourth area IV is C4, C1>C2>C3> C
Even if each curvature is set so as to satisfy 4, it is possible to enhance the directionality of the ball after hitting due to the above-mentioned reason, and the golf club head can be easily designed, and the cost thereof can be reduced.

Since the first area I and the second area II shown in FIG. 7 have a higher hitting speed than the third area III and the fourth area IV, the face surface 2 is divided into two parts by the x axis. A face surface (first portion) located on the toe portion 5 side with this axis as a boundary
The curvature of the curved surface of the area I and the second area II is set to the face surface (the third area III and the fourth area III) located on the heel portion 4 side.
It may be set larger than the curvature of the curved surface of area IV).
This also makes it possible to improve the directionality of the ball after hitting, and further, to manufacture the golf club head 1 at a lower cost.

When the face surface 2 is divided into two parts on the y axis, the first area I and the third area III on the side of the sole surface 7, which is the lower side, are the second area on the side of the upper top portion 6. I
The hitting speed is faster than I and 4th area IV. Therefore,
Face surface 2 located on the side of the sole surface 7 with the y-axis as a boundary
Also, by setting the curvature of the curved surface of the above to be larger than the curvature of the curved surface of the face surface 2 located on the side of the top portion 6,
The directionality of the ball after hitting can be enhanced, and the manufacturing cost of the golf club head can be reduced.

In the above-mentioned embodiment, the curvature of the face surface 2 is changed with the x-axis or the y-axis, or both of these axes as the boundaries. At that time, the x-axis and the y-axis serving as the boundaries are changed.
It is needless to say that the face surface 2 should be formed so that the curvature does not change rapidly on the axis, that is, the curved surface is smooth even at the boundary.

By the way, it is possible to set the curvatures of the face surface portion W1 near the top portion 6 and the face surface portion W2 near the sole surface 7 according to the configurations of the above-described embodiments. If the curvatures of W1 and W2 are too large, the ball after hitting may suddenly rise, or the rise may be extremely suppressed, and it may be difficult to extend the flight distance.

From this point of view, in each of the above-described configurations, the face surface portion W1 near the top portion 6 and the face surface portion W2 near the sole surface 7 are exceptionally changed in curvature. It is set to be smaller than the curvature of the curved surface of the face surface portion between the two portions, and particularly these portions W1,
It is desirable to form W2 flat rather than curved. With this configuration, the directionality of the ball can be enhanced by the above-described configurations, and the face surface portions W1, W can be formed.
Even if the ball is hit with 2, the flight distance can be greatly extended.

Although the respective embodiments have been described above by taking the wood type golf club as an example, the present invention is also applicable to other types of golf club heads.

[0049]

According to the structure of the first aspect, the curvature is set according to the speed of each point on the face surface at the time of hitting the ball, so that the directionality of the ball after hitting can be made more reliable than before. Can be improved.

According to the structures described in claims 2 to 5, in addition to the above-mentioned effects, there is an advantage that the golf club head can be easily manufactured.

According to the constitutions of claims 6 and 7, in addition to the above-mentioned effects, when the ball is hit with the face surface portion near the top portion or the face surface portion near the sole surface, the flight distance is also improved. The advantage is that it can be stretched.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a state of movement of a golf club head when a golf club is swung and a ball is hit.

FIG. 2 is a front view for explaining that the speed of each part of the golf club head is different when hitting a ball.

FIG. 3 is a diagram showing a velocity distribution on a face surface when hitting a ball.

FIG. 4 is a diagram showing a velocity distribution on a face surface when hitting a ball.

FIG. 5 is an explanatory diagram illustrating an embodiment of the present invention.

FIG. 6 is a diagram for explaining the effect of the above embodiment.

FIG. 7 is a front view of the golf club head showing a state in which the face surface is divided into four areas.

FIG. 8 is an explanatory view showing a conventional golf club head having a flat face surface and its defects.

FIG. 9 is an explanatory view showing a conventional golf club head having a convex curved surface and its defects,
It is a figure which shows the curved surface in the horizontal surface of a golf club head.

FIG. 10 is an explanatory view showing a curved surface in a vertical plane of a conventional golf club head.

[Explanation of symbols]

 1 golf club head 2 face surface 4 heel portion 5 toe portion 6 top portion 7 sole surface I 1st area II 2nd area III 3rd area IV 4th area S sweet spot T arbitrary point W1 face surface portion W2 face surface portion

Front page continuation (72) Inventor Yuji Mori 288, Matsuhidai, Matsudo-shi, Chiba Marmangolf Co., Ltd. Matsudo factory (72) Inventor Yasushi Sasaki 288, Matsuhidai, Matsudo-shi, Chiba Marmangolf Co., Ltd. Matsudo factory

Claims (7)

[Claims] 1. A golf club head having a face surface formed into a convex curved surface, wherein the velocity of a sweet spot when hitting a ball is V, the velocity when hitting an arbitrary point on the face surface other than the sweet spot is V1, and a sweet When the angle formed by the normal line of the spot and the normal line of the arbitrary point is θ, the angle θ of the point satisfying V1> V is set larger than the angle θ of the point satisfying V1 <V. And a golf club head. 2. A golf club head having a face surface formed into a convex curved surface, wherein an axis line perpendicular to the ground at the time of hitting and passing through the sweet spot is the x axis, and the sweet spot is perpendicular to the x axis. Of the four areas of the face surface divided by the x-axis and the y-axis, with the axis extending from the toe side to the heel side as the y-axis,
The area on the sole side and the toe side is the first area, the area on the top side and the toe side is the second area, the area on the sole side and the heel side is the third area, and the top side and While making the area on the heel side the fourth area,
The angle formed by the normal line of the central point of the first area and the normal line of the sweet spot is θ1, and the angle formed by the normal line of the central point of the second area and the normal line of the sweet spot is θ2, the third When the angle between the normal line of the point near the center of the area and the normal line of the sweet spot is θ3, and the angle between the normal line of the point near the center of the fourth area and the normal line of the sweet spot is θ4, θ1 A golf club head, wherein each angle is set so as to satisfy &gt;&thgr; 2 &gt;&thgr; 3 &gt;&thgr; 4. 3. A golf club head having a face surface formed into a convex curved surface, wherein an axis line perpendicular to the ground at the time of hitting and passing through the sweet spot is the x axis, and the sweet spot is perpendicular to the x axis. Of the four areas of the face surface divided by the x-axis and the y-axis, with the axis extending from the toe side to the heel side as the y-axis,
The area on the sole side and the toe side is the first area, the area on the top side and the toe side is the second area, the area on the sole side and the heel side is the third area, and the top side and While making the area on the heel side the fourth area,
The average curvature of the curved surface of the first area is C1, the average curvature of the curved surface of the second area is C2, and the average curvature of the curved surface of the third area is C.
Let C4 be the average curvature of the curved surfaces of the 3rd and 4th areas.
A golf club head, wherein each curvature is set so as to satisfy 1>C2>C3> C4. 4. A golf club head having a convexly curved face surface, wherein a toe portion is the boundary of the x-axis, where the x-axis is an axis perpendicular to the ground when hitting the ball and passing through the sweet spot. A curvature of the curved surface of the face surface located on the side is set to be larger than the curvature of the curved surface of the face surface located on the heel side. 5. A golf club head having a face surface formed into a convex curved surface, wherein an axis line perpendicular to the ground at the time of hitting the ball and passing through the sweet spot is the x axis, and the sweet spot is perpendicular to the x axis. When the axis extending from the toe side to the heel side is defined as the y-axis, the curvature of the curved surface of the face surface located on the sole surface side with the y-axis as a boundary is defined as the curvature of the curved surface of the face surface located on the top side. A golf club head characterized by being set larger than the curvature. 6. The curvatures of the face surface portion near the top portion and the face surface portion near the sole surface are set to be smaller than the curvature of the curved surface of the face surface portion between the two portions. 5. The golf club head according to any one of 5. 7. The golf club head according to claim 6, wherein the face surface portion near the top portion and the face surface portion near the sole surface are formed flat.