JP2013048963A - Golf club head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf club head advantageous in enlarging a sweet area while increasing a carry.SOLUTION: A horizontal direction from the toe 8 side to the heel 5 side of a face surface 1 of a golf club head 10 is set as an X-direction, and a vertical upward direction is set as a Y-direction. Coordinates of a center point C of the face surface 1 are set to (0, 0). When the coordinates of a center-of-gravity point P are (X1, Y1) and the coordinates of a maximum deflection point Q are (X2, Y2), the following conditions are satisfied: X1 is within a range of 0 mm to 10 mm, Y1 is within a range of 0 to 10 mm, X2 is within a range of -10 mm to 0 mm, Y2 is within a range of -10 mm to 10 mm, a distance ΔL between the center-of-gravity point P and the maximum deflection point Q is 5 to 15 mm, and the angle φ defined by a straight line LA connecting the center-of-gravity point P to the maximum deflection point Q, and the X-direction is 0 to 70 degrees.

Description

  The present invention relates to a method for designing a golf club head.

There is provided a golf club head that improves the flight distance of a hit ball by appropriately arranging the position of the sweet spot and the position of the highest repulsion point on the face surface (see Patent Document 1).
Here, the sweet spot is an intersection of a straight line passing through the center of gravity of the head perpendicular to the face surface and the face surface, in other words, a center of gravity point.
The maximum repulsion point is a point having the maximum restitution coefficient among points on the face surface.
Here, the coefficient of restitution is measured by the USGA (National Golf Association) COR measurement method (Procedure for Measuring the Velocity Ratio of a Club Head for Conformance to Rule 4-1e, Revision 2 (February 8, 1999)). is there.
The coefficient of restitution is measured while the golf club head is stationary.
In this golf club head, the maximum repulsion point is arranged in the vicinity of the center point of the face surface that is in the vicinity of the center of the hitting point distribution of the golfer, thereby increasing the flight distance. In addition, by arranging the sweet spot near the heel of the face surface, even when hitting near the heel of the face surface, a flight distance is secured to some extent.
In this case, the initial velocity of the ball is maximized by hitting the ball at the highest rebound point.
Here, assuming that the point on the face surface where the initial velocity of the ball is the highest is the highest initial velocity point, the highest repulsion point coincides with the highest initial velocity point.

JP 2008-188366 A

By the way, when a ball is hit on the face surface by actually swinging the golf club, the speed distribution on the face surface is not uniform, and the speed distribution on the face surface depends on the shaft length dependency and the golf club head rolling (shaft Rotation around)).
Specifically, the speed of the face surface gradually increases from the upper part on the heel side to the lower part on the toe side.
Examination of the prior art based on such knowledge revealed the following problems.
That is, when the golf club is actually swung and the ball is hit with the face surface, the position of the maximum initial speed point is affected by the speed distribution of the face surface as described above, so that the position of the maximum rebound point is Shifts to the toe side and downward.
Therefore, a golf club head in which the maximum repulsion point is arranged based on the conventional technology is not necessarily sufficient for increasing the flight distance.
Further, in golf club heads, it is important to expand the sweet area, that is, to expand the hitting point area where the initial speed of 99% or more of the maximum initial speed point can be obtained on the face surface. The area has not been expanded.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a golf club head design method that is advantageous in increasing the flight distance and expanding the sweet area. is there.

  In order to achieve the above object, the golf club head designing method of the present invention has a horizontal direction from the toe side to the heel side of the face surface of the golf club head in a state where the golf club head is set along the lie angle. The X direction, the vertically upward direction is the Y direction, the coordinates of the center point of the face surface are (0, 0), and the coordinates of the center point of the center of gravity of the golf club head projected perpendicularly on the face surface are When (X1, Y1) and the coordinates of the maximum deflection point in the primary vibration of the face surface are (X2, Y2), X1 is in the range of 0 mm to 10 mm, and Y1 is 0 mm to 10 mm. Within a range, X2 is within a range of −10 mm to 0 mm, Y2 is within a range of −10 mm to 10 mm, and the center of gravity is separated from the maximum deflection point. Golf in which the distance is in the range of 5 to 15 mm, the angle between the straight line connecting the center of gravity and the maximum deflection point and the X direction is in the range of 0 to 70 degrees, and the golf club head is attached to the shaft When swinging a club and hitting a golf ball with the face surface, the hit point of the face surface at which the maximum initial speed of the golf ball is obtained is the maximum initial speed point, and the coordinates of the maximum initial speed point are (X3, Y3) X3 was set in the range of −5 mm to 5 mm, and Y3 was set in the range of −5 mm to 5 mm.

According to the present invention, the gravity center point and the maximum deflection point are arranged in consideration of the velocity distribution of the face surface, so that the position of the highest initial velocity point of the face surface is the vicinity of the center of the hitting point distribution of the golfer. It can match or be close to the center point, which is advantageous in increasing the flight distance.
Further, by enlarging the sweet area, it is advantageous for effectively suppressing the flight distance from decreasing even if the hit points vary.

1 is a front view showing a golf club head 10 which is an object of a golf club head design method of the present invention. It is a block diagram which shows the structure of the computer 30 used in order to perform the method of this invention. 2 is a functional block diagram of a computer 30. FIG. 4 is an explanatory diagram of rolling of the head body 4 of the golf club head 10. FIG. 4 is an explanatory diagram showing a speed distribution set on the face surface 1 of the golf club head 10. FIG. FIG. 6 is an explanatory diagram showing a velocity distribution of the face surface 1 when the amount of rolling of the head body 4 is minimum. 6 is an explanatory diagram showing a velocity distribution of the face surface 1 when the amount of rolling of the head body 4 is an average value. FIG. FIG. 6 is an explanatory diagram showing a velocity distribution of the face surface 1 when the amount of rolling of the head body 4 is maximum. (A) and (B) are schematic diagrams for explaining the deviation of the maximum initial speed point R due to the influence of the velocity distribution of the face surface 1. (A), (B), and (C) are schematic diagrams for explaining the deviation of the maximum initial speed point R due to the influence of the velocity distribution of the face surface 1. (A) is a front view of the golf club head 10 showing the positions of the center of gravity point P, the maximum deflection point Q, and the maximum initial speed point R, and (B) is a component in which the position of the center of gravity point P contributes to the ball initial speed and the maximum deflection. It is a schematic diagram which shows the relationship between the position of the point Q and the component which contributes to ball | bowl initial velocity. (A) is a front view of the golf club head 10 showing the positions of the center of gravity point P, the maximum deflection point Q, and the maximum initial speed point R, and (B) is a component in which the position of the center of gravity point P contributes to the ball initial speed and the maximum deflection. It is a schematic diagram which shows the relationship between the position of the point Q and the component which contributes to ball | bowl initial velocity. It is explanatory drawing which shows an example of the definition method of a face center. It is explanatory drawing which shows an example of the definition method of a face center. It is explanatory drawing which shows an example of the definition method of a face center. It is explanatory drawing which shows an example of the definition method of a face center. 1 is a cross-sectional view of a golf club head 10 showing a relationship between a gravity center position P0 and a gravity center point P. FIG. 1 is a front view of a golf club head 10 for explaining a definition of a contour line I of a face surface 1. FIG. 1 is a cross-sectional view of a golf club head 10 for explaining a definition of a contour line I of a face surface 1. FIG. 3 is a front view of the golf club head 10 for explaining the definition of the center point C of the face surface 1. FIG. 3 is an explanatory diagram showing a velocity distribution of a face surface 1, a center of gravity point P, a maximum deflection point Q, and a maximum initial speed point R. FIG. (A) is a front view of the golf club head 10 showing the positions of the center of gravity point P, the maximum deflection point Q, and the maximum initial speed point R, and (B) is a component in which the position of the center of gravity point P contributes to the ball initial speed and the maximum deflection. It is a schematic diagram which shows the relationship between the position of the point Q and the component which contributes to ball | bowl initial velocity. It is a schematic diagram showing the relationship between the separation distance ΔL between the center of gravity point P and the maximum deflection point Q and the initial ball speed Vb. (A) is a front view of the golf club head showing the positions of the center of gravity P, the maximum deflection point Q, and the maximum initial speed point R in the first golf club head, and (B) is the center of gravity P in the first golf club head. FIG. 6 is a schematic diagram showing a relationship between a component that contributes to the initial velocity of the ball and a component that contributes to the initial velocity of the ball with the position of the maximum deflection point Q. (A) is a front view of the golf club head showing the positions of the center of gravity P, the maximum deflection point Q, and the maximum initial speed point R in the second golf club head, and (B) is the center of gravity P in the second golf club head. FIG. 6 is a schematic diagram showing a relationship between a component that contributes to the initial velocity of the ball and a component that contributes to the initial velocity of the ball with the position of the maximum deflection point Q. (A) is a front view of the golf club head showing the positions of the center of gravity P, the maximum deflection point Q, and the maximum initial speed point R in the third golf club head, and (B) is the center of gravity P in the third golf club head. FIG. 6 is a schematic diagram showing a relationship between a component that contributes to the initial velocity of the ball and a component that contributes to the initial velocity of the ball with the position of the maximum deflection point Q. (A) is a front view of the golf club head showing the positions of the center of gravity P, the maximum deflection point Q, and the maximum initial speed point R in the fourth golf club head, and (B) is the center of gravity P in the fourth golf club head. FIG. 6 is a schematic diagram showing a relationship between a component that contributes to the initial velocity of the ball and a component that contributes to the initial velocity of the ball with the position of the maximum deflection point Q. (A) is a front view of the golf club head showing the positions of the center of gravity P, the maximum deflection point Q, and the maximum initial speed point R in the fifth golf club head, and (B) is the center of gravity P in the fifth golf club head. FIG. 6 is a schematic diagram showing a relationship between a component that contributes to the initial velocity of the ball and a component that contributes to the initial velocity of the ball with the position of the maximum deflection point Q. 2 is a front view of a golf club head showing a hitting point position on a face surface 1. FIG. It is a table | surface which shows the experimental result of Experimental example 1 thru | or 17. FIG. 6 is an explanatory diagram showing a positional relationship among a center of gravity point P, a maximum deflection point Q, and a maximum initial speed point R in a toe-side center of gravity head. It is explanatory drawing which shows the positional relationship of the gravity center point P, the largest deflection | deviation point Q, and the highest initial speed point R in a heel gravity center head. It is explanatory drawing which shows the relationship between the hit point position and flying distance in a toe side gravity center head and a heel gravity center head. It is explanatory drawing which shows an example of the measurement result of the hit point position by many golfers.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a golf club head that is an object of the designing method of the present invention will be described.
As shown in FIG. 1, the golf club head 10 includes a metal hollow structure head body 4.
The metal material of the head body 4 is preferably a high strength low specific gravity metal such as a titanium alloy or an aluminum alloy.
The head body 4 includes a face surface 1 that hits a golf ball, and a crown portion 2 and a sole portion 3 that are connected to the face surface 1.
Further, the crown portion 2 is provided with a hosel 7 connected to the shaft 6 at a position close to the heel 5 on the face surface 1 side.
A toe 8 is located on the opposite side of the head body 4 from the heel 5 when the face surface 1 is viewed from the front.

An embodiment of such a golf club head design method will be described in detail below.
The present inventors conducted finite element analysis using a golf club head model, which is a finite element model of the golf club head 10 described above, and conducted experiments and verifications using a swing robot.
As a result, the sweet area and the flight area when the velocity distribution of the face surface 1 during the swing of the golf club, the positional relationship between the center of gravity of the golf club head 10 and the maximum deflection point of the face surface 1 satisfy a specific condition. It has been found that it is advantageous for increasing the distance.
In the present specification, the center of gravity point refers to a point obtained by projecting the position of the center of gravity of the golf club head 10 perpendicularly to the face surface 1.
The maximum deflection point refers to the maximum deflection point in the primary vibration of the face surface 1.
Further, in the present specification, the sweet area refers to a region on the face surface 1 where the initial velocity of the golf ball when hitting the golf ball on the face surface 1 is equal to or greater than a predetermined threshold value.
As another definition of the sweet area, an area on the face surface 1 where the flight distance of the golf ball when hitting the golf ball on the face surface 1 is equal to or greater than a predetermined threshold value may be referred to.
Hereinafter, when it is simply described as “sweet area”, or when it is described as “sweet area relating to initial speed”, the former sweet area is indicated.
Further, when referring to the latter sweet area, the term “sweet area relating to flight distance” will be used.
Hereinafter, it will be described that it is advantageous to increase the sweet area and the flight distance when the velocity distribution of the face surface 1 and the positional relationship between the center of gravity and the maximum deflection point satisfy specific conditions.

FIG. 2 is a block diagram showing a configuration of a computer 30 for performing a finite element analysis of the golf club head 10.
The computer 30 includes a CPU 32, a ROM 34, a RAM 36, a hard disk device 38, a disk device 40, a keyboard 42, a mouse 44, a display 46, a printer 48, an input / output interface 50, etc. connected via an interface circuit (not shown) and a bus line. have.
The ROM 34 stores a control program and the like, and the RAM 36 provides a working area.
The hard disk device 38 stores a finite element analysis program for performing finite element analysis of the golf club head 10.
As the finite element analysis program, various conventionally known commercially available finite element analysis software that performs finite element analysis, for example, ABAQUS (registered trademark of SIMULIA Americas) can be used.
The disk device 40 records and / or reproduces data on a recording medium such as a CD or a DVD.
The keyboard 42 and the mouse 44 receive an operation input by the operator.
The display 46 displays and outputs data, and the printer 48 prints and outputs data. The display 46 and the printer 48 output data.
The input / output interface 50 exchanges data with an external device.

FIG. 3 is a functional block diagram of the computer 30.
As shown in FIG. 3, the computer 30 is functionally configured to include an input unit 30A, a processing unit 30B, and an output unit 30C.
The input means 30A inputs data necessary for analyzing the golf club head 10 by the finite element method.
The data includes a finite element analysis data d1 for setting a golf club head model composed of a finite element model and analyzing the set golf club head model by a finite element method.
The processing means 30B constructs a golf club head model based on the finite element analysis data d1.
Further, the processing means 30B performs a finite element analysis using the golf club head model on the velocity distribution, the center of gravity, the maximum deflection point, etc. of the face surface 1 in a golf club head model, which will be described later, based on the second data d2. Ask by.
The processing means 30B is realized by loading a finite element analysis program stored in the hard disk device 38 into the RAM 36 and the CPU 32 operating based on these programs.
The output means 30C outputs the calculation result by the processing means 30B.

Hereinafter, the analysis of the golf club head 10 will be described.
First, the processing means 30B sets a golf club head model composed of a finite element model based on the finite element analysis data d1 supplied from the input means 30A.
The processing means 30B also sets a golf ball model composed of a finite element model for the golf ball based on the finite element analysis data supplied from the input means 30A in the same manner as the golf club head model.
Specifically, the head body 4 is divided into a plurality of finite elements Xijk, and the golf ball is divided into a plurality of finite elements Yijk (i, j, k are integers).
Here, the finite element is an element for performing analysis by the finite element method, and examples thereof include a beam element, a shell element, and a solid element.
Examples of the physical property values necessary for the calculation include a loft angle, a center of gravity depth, a bulge & roll radius, an FP value (face progression), an inertia moment, a head mass, and the like. These physical property values are included in the finite element analysis data d1.

Next, the processing means 30B obtains the velocity distribution of the face surface 1 by calculation using the golf club head model set above, and sets the velocity distribution of the face surface 1 to the face surface 1.
Here, the speed distribution of the face surface 1 means the speed distribution of the face surface 1 immediately before hitting when the player hits a golf ball with a golf club having the head body 4.
The velocity distribution of the face surface 1 is mainly determined from a component depending on the length of the shaft 6 and a component due to rolling of the head body 4 (rotation around the shaft 6).
As shown in FIG. 4, the component depending on the length of the former shaft 6 is maximized at a point A where the perpendicular of the extension line L of the central axis of the shaft 6 contacts the sole portion 3 of the head body 4.
The latter component depending on the rolling of the head main body 4 is maximum at a point B (the end portion on the toe 8 side of the head main body 4) farthest from the extension line L of the central axis of the shaft 6.
Therefore, as shown in FIG. 5, the face speed is distributed so as to gradually increase from the upper part a on the heel 5 side to the lower part g on the toe 8 side of the face surface 1. In FIG. 5, a contour line v is shown for each speed of 0.5 m / s.
Here, the contour line v of the speed distribution is a line connecting points of the same face speed on the face surface 1 in order to show the distribution of the face speed.
In the finite element analysis, the length of the shaft 6 and the size of the rolling of the head main body 4 are determined based on the length of the shaft 6 in the average golf club and the size of the rolling of the head main body 4 in the average golf club. Set to.

Next, in order to confirm the validity of the calculation result of the velocity distribution of the face surface 1 obtained by the finite element analysis as described above, swing data of a large number of golfers was measured.
More specifically, the face speed distribution was obtained by measuring the face speed of the face when a large number of golfers actually swing the golf club.
The face speed was measured using a conventionally known measuring device as disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-34619 (golf club head behavior measuring device).
FIG. 6 is an explanatory diagram showing the velocity distribution of the face surface 1 when the amount of rolling of the head body 4 is minimum.
FIG. 7 is an explanatory diagram showing the velocity distribution of the face surface 1 when the amount of rolling of the head body 4 is an average value.
FIG. 8 is an explanatory diagram showing the velocity distribution of the face surface 1 when the amount of rolling of the head body 4 is maximum.
6 to 8, the horizontal axis indicates the coordinate value X (mm) in the X direction, and the vertical axis indicates the coordinate value Y (mm) in the Y direction. In addition, the coordinates of the center point C of the face surface 1 are (0, 0).
Each hatching indicates the speed of the face surface 1 (face speed) Vf (m / sec), and the speed of the face surface 1 gradually increases from the upper part on the heel 5 side to the lower part on the toe 8 side of the face surface 1. It is distributed to become.
The hatched rectangular area indicates an impact area that is a target for measuring the velocity distribution.
In the present embodiment, the velocity distribution of the face surface 1 obtained by the finite element analysis has almost the same result as the velocity distribution of the face surface 1 when the rolling amount of the head body 4 shown in FIG. The validity of the numerical value of the velocity distribution of the face surface 1 calculated by the finite element analysis could be confirmed.

Next, the relationship among the gravity center point P, the maximum deflection point Q, and the maximum initial speed point R (the point on the face surface 1 at which the initial speed of the ball is the highest) when the speed distribution of the face surface 1 is not considered will be described.
FIG. 9 is a schematic diagram showing a positional relationship among the center of gravity point P, the maximum deflection point Q, and the maximum initial speed point R when the velocity distribution of the face surface 1 is not considered.
It is considered that the initial ball velocity at the hitting point of the face surface 1 is determined by a value obtained by adding the component contributed by the position of the center of gravity P and the component contributed by the position of the maximum deflection point Q.
In the figure, reference signs p1 and p2 indicate contour lines indicating a distribution indicating the component to which the position of the center of gravity P contributes, and the magnitude relationship between the contributing components is p1> p2.
Symbols q1 and q2 indicate contour lines indicating distributions indicating components to which the position of the maximum deflection point Q contributes, and the magnitude relationship between the contributing components is q1> q2.
Therefore, as shown in FIG. 9, the maximum initial speed point R is located on a substantially straight line LA connecting the center of gravity P and the maximum deflection point Q. However, the maximum initial speed point R may slightly deviate from the straight line LA depending on the head shape, the bulge of the face surface, the roll, and the like.
That is, when the velocity distribution of the face surface 1 is not taken into consideration, if the gravity center point P and the maximum deflection point Q are arranged so that the maximum initial velocity point R matches or is close to the center point C of the face surface 1, This is advantageous in increasing the sweet area and flight distance.

When the golfer swings the golf club and hits the golf ball with the face surface 1 of the golf club head 10, the velocity distribution of the face surface 1 occurs as described above.
Since the maximum initial speed point R is affected by such a face speed, it deviates from the position shown in FIG.
As shown in FIG. 10 (A), it is orthogonal to the contour line v (see FIG. 5) indicating the velocity distribution of the face surface 1, in other words, connecting the points where the amount of change in the face speed is maximum, and the highest A straight line L0 passing through the initial speed point R is assumed.
Then, as shown in FIG. 10 (B), the maximum initial speed point R is affected by the velocity distribution of the face surface 1, and when the angle at which the straight line LA and the straight line L0 intersect is θ, it is approximately θ. It moves in a direction along the angle (for example, about 3 to 5 mm). The angle θ varies depending on the deflection amount distribution and the face surface velocity distribution. Specifically, the highest rebound point R moves closer to the toe 5 side and downward.
Further, as shown in FIG. 10C, the maximum initial velocity point R moves further downward due to the influence of the face surface 1 having a curved surface (R is given to the face surface 1). (For example, a total moving distance of about 6 to 10 mm).
As shown in FIG. 10 (C), the reason why the maximum initial speed point R moves further downward is as follows. That is, a curved surface (bulge) in the direction connecting the toe 8 and the heel 5 and a curved surface (roll) in the direction connecting the crown 4 and the heel 3 are formed on the face surface 1 of a normal wood head.
By forming such a curved surface on the face surface 1, the loft angle of the face surface 1 changes. As a result, the maximum initial speed point R moves downward. The downward movement amount changes not only due to the difference in the curved surface of the face surface 1 but also due to the deflection amount distribution and the face surface velocity distribution.
Accordingly, when the golf club is actually swung and the ball is hit with the face surface 1, the position of the maximum initial speed point R is affected by the velocity distribution of the face surface 1 as described above, and therefore, FIG. The position is shifted closer to the toe side and lower than the position of the maximum rebound point R shown in FIG.
That is, it was found that the actual maximum initial speed point R is located at a position deviating from the straight line LA connecting the center of gravity P and the maximum deflection point Q due to the influence of the velocity distribution of the face surface 1.
The present invention is based on such knowledge, and the center of gravity P and the maximum are set so that the actual maximum initial velocity point R matches or is close to the center point C of the face surface 1 near the center of the golfer's hitting point distribution. By arranging the deflection point Q, the flight distance can be increased and the sweet area can be expanded. As a result, even when the hit points vary, the flight distance can be effectively suppressed.

FIG. 11 is a front view of the golf club head 10 showing the positional relationship among the center of gravity point P, the maximum deflection point Q, and the maximum initial speed point R in the first embodiment.
In this embodiment, with the golf club head 10 set according to the lie angle, the horizontal direction from the toe 8 side to the heel 5 side of the face surface 1 of the golf club head 10 is the X direction, and the vertical upward direction is Y. It is assumed that the coordinate of the center point C of the face surface 1 is (0, 0).

  The center point C of the face surface 1 is the geometric center of the face surface 1, and is defined as follows, for example. It should be noted that various conventionally known defining methods as described below can be adopted as the defining method of the center point C of the face surface 1.

First, a method for defining the center point C of the face surface 1 when the boundary between the face surface 1 and the other head main body 4 is clear, in other words, when the periphery of the face surface 1 is specified by the ridgeline will be described. To do. In this case, the face surface 1 is clearly defined.
FIG. 13 to FIG. 16 are explanatory diagrams showing an example of a face center defining method.
(1) First, as shown in FIG. 13, the golf club head 10 (head main body 4) is placed on a horizontal ground so that the lie angle and the face angle become prescribed values. The state of the golf club head 10 at this time is set as a reference state. Note that the set values of the lie angle and the hook angle are values described in, for example, a product catalog.

(2) Next, a temporary center point c0 in the direction connecting the crown portion 2 and the sole portion 3 is obtained.
That is, as shown in FIG. 13, a perpendicular line f <b> 0 that intersects with the approximate center point of a line parallel to the ground connecting the toe 8 and the heel 5 (hereinafter referred to as a horizontal line) is drawn.
The midpoint of the point a0 where the perpendicular f0 and the upper edge of the face surface 1 intersect and the middle point of the b0 where the perpendicular f0 and the lower edge of the face surface 1 intersect are defined as a temporary center point c0.

(3) Next, as shown in FIG. 14, a horizontal line g0 passing through the temporary center point c0 is drawn.
(4) Next, as shown in FIG. 15, the point d0 where the horizontal line g0 and the edge on the toe 8 side of the face surface 1 intersect, and the point e0 where the horizontal line g0 and the edge on the heel 5 side of the face surface 1 intersect. The midpoint is defined as a temporary center point c1.
(5) Next, as shown in FIG. 16, a perpendicular line f1 passing through the temporary center point c1 is drawn, and the perpendicular line f1 and the upper edge of the face surface 1 intersect with each other, and the perpendicular line f1 and the lower edge of the face surface 1 The midpoint of the b1 point where the two intersect is defined as the temporary center point c2.
Here, if the temporary center points c1 and c2 match, that point is defined as the center point C of the face surface 1.
If the temporary center points c1 and c2 do not match, the procedures (2) to (5) are repeated.
Since the face surface 1 has a curved surface, the length of the horizontal line g0 and the lengths of the vertical lines f0 and f1 when determining the midpoint of the horizontal line g0 and the midpoints of the vertical lines f0 and f1 are the curved surfaces of the face surface 1. The length along the line shall be used.

  Next, a method for defining the center point C of the face surface 1 when the periphery of the face surface 1 and the other head body 4 are connected by a curved surface and the face surface 1 cannot be clearly defined will be described.

As shown in FIG. 17, the golf club head 10 is hollow, the symbol P0 indicates the center of gravity position of the golf club head 10, and the symbol Lp is a straight line connecting the center of gravity position P0 and the center of gravity point P. Lp is a perpendicular of the face surface 1 passing through the gravity center position P0.
Here, as shown in FIG. 18, a large number of planes H1, H2, H3,..., Hn including a straight line Lp connecting the gravity center position P0 and the gravity center point P are considered.
In a cross section when the golf club head 10 is broken along the planes H1, H2, H3,..., Hn, the curvature radius r0 of the outer surface of the golf club head 10 is measured as shown in FIG.
When measuring the radius of curvature r0, it is assumed that there are no face lines or punch marks on the face surface 1.
The curvature radius r0 is continuously measured from the center point C of the face surface 1 outward (upward and downward in FIG. 19).
In the measurement, a portion where the radius of curvature r0 is initially equal to or smaller than a predetermined value is defined as an outline I representing the periphery of the face surface 1. The predetermined value is, for example, 200 mm.
A region surrounded by the contour line I determined based on a large number of planes H1, H2, H3,..., Hn is defined as the face surface 1 as shown in FIGS.
Next, as shown in FIG. 20, the golf club head 10 (head main body 4) is placed on a horizontal ground so that the lie angle and the face angle become specified values.
The straight line LT passes the toe side point PT of the face surface 1 and extends in the vertical direction.
The straight line LH passes through the heel side point PH of the face surface 1 and extends in the vertical direction.
The straight line LC is parallel to the straight line LT and the straight line LH. The distance between the straight line LC and the straight line LT is equal to the distance between the straight line LC and the straight line LH.
Reference symbol Pu indicates an upper point of the face surface 1, and reference symbol Pd indicates a lower point of the face surface 1. The upper point Pu and the lower point Pd are both intersections of the straight line LC and the contour line I.
The center point C is defined by the midpoint of the line segment connecting the upper point Pu and the lower point Pd.

Returning to FIG. 11, the description will be continued.
In the present embodiment, the golf club head 10 is designed to satisfy the following conditions when the coordinates of the center of gravity P are (X1, Y1) and the coordinates of the maximum deflection point Q are (X2, Y2).
X1 is in the range of 0 mm to 10 mm, and Y1 is in the range of 0 mm to 10 mm.
X2 is in the range of −10 mm to 0 mm, and Y2 is in the range of −10 mm to 10 mm.
11 shows the case where X2 is in the range of −10 mm to 0 mm and Y2 is in the range of 0 mm to 10 mm, and FIG. 12 is the case where X2 is in the range of −10 mm to 0 mm. Is in the range of −10 mm to 0 mm. 11 will be described below, but the range of the center of gravity point P and the maximum deflection point Q is also applied in the case of FIG.
In FIG. 11, symbol A1 indicates the range of the coordinates (X1, Y1) of the barycentric point P, and symbol A2 indicates the range of the coordinates (X2, Y2) of the maximum deflection point Q.
The distance ΔL between the center of gravity P and the maximum deflection point Q is set within a range of 5 to 15 mm.
An angle φ formed by the straight line LA connecting the center of gravity P and the maximum deflection point Q with the X direction is set within a range of 0 to 70 degrees.
In this specification, the angle φ is a positive value of the angle φ in a range where the slope of the straight line connecting the center of gravity P and the maximum deflection point Q is positive on the coordinate plane formed by the X axis and the Y axis. And the value of the angle φ in the range where the inclination is negative is a negative value.
By arranging the gravity center point P and the maximum deflection point Q so as to satisfy such conditions, the position of the maximum initial velocity point R when the golfer actually swings the golf club and hits the ball with the face surface 1 is determined. It can match or be close to the center point C of the face surface 1 near the center of the golfer's hitting point distribution, which is advantageous in increasing the flight distance. Furthermore, the sweet area can be enlarged, and therefore, even if the hit points vary, it is advantageous in effectively suppressing the decrease in the flight distance.

Here, it will be described that the center point C of the face surface 1 is near the center of the hitting point distribution of the golfer.
FIG. 34 is an explanatory diagram showing an example of measurement results of hitting point positions by a large number of golfers.
Specifically, the hit points when a total of 3757 swingers of 743 golfers have swung for one golf club head are measured, and the hit point positions are plotted on the face surface 1 by the symbol “♦”.
Numerical values on the X-axis and Y-axis are coordinate values indicating the hit point position when the center point C of the face surface 1 is the origin (0, 0), and the unit is mm.
The average value of the hitting positions is indicated by the symbol □ in the figure, and was as follows.
X coordinate value: 1.8 mm (1.8 mm in the heel 5 direction from the center point C)
Y coordinate value: 3.9 mm (3.9 mm in the crown 2 direction from the center point C)
That is, the center of the golfer's hitting point distribution is located near the center point C.
Therefore, when the golfer actually swings the golf club and hits the ball with the face surface 1, if the position of the highest initial velocity point R matches or is close to the center point C of the face surface 1, the majority of golfers Therefore, it is advantageous in increasing the flight distance, and the sweet area can be enlarged. Therefore, even if the hit points vary, it is advantageous in effectively suppressing the decrease in the flight distance.

FIG. 21 is an explanatory diagram showing the velocity distribution of the face surface 1, the barycentric point P, the maximum deflection point Q, and the maximum initial speed point R.
In FIG. 21, the horizontal axis indicates the coordinate value X (mm) in the X direction, and the vertical axis indicates the coordinate value Y (mm) in the Y direction.
Each hatching indicates the speed (face speed) Vf (m / sec) of the face surface 1, and the speed of the face surface 1 is from the upper part of the face surface 1 on the heel 5 side to the toe 8 side as shown in FIG. It is distributed so as to gradually increase toward the lower part of.

22A is a front view of the golf club head 10 showing the positions of the center of gravity point P, the maximum deflection point Q, and the maximum initial speed point R, and FIG. 22B is a component in which the position of the center of gravity point P contributes to the ball initial speed. It is a schematic diagram which shows the relationship between the position of the maximum deflection point Q and the component which contributes to ball | bowl initial velocity.
The initial ball speed Vb at a certain hitting point is considered to be determined by the contribution of three factors: the face speed Vf, the position of the center of gravity P, and the position of the maximum deflection point Q.
That is, the higher the face speed Vf at the hitting point, the higher the ball initial speed Vb.
Further, the closer the center of gravity P is to the hit point, the higher the ball initial speed Vb becomes.
Further, the closer the maximum deflection point Q is to the hit point, the higher the ball initial speed Vb becomes.
That is, as shown in FIG. 22B, the initial ball velocity Vb at a certain hit point is a component contributed by the face speed Vf, a component contributed by the position of the center of gravity P, and a component contributed by the position of the maximum deflection point Q. It is thought that it is determined by the sum of
In FIG. 22A, the broken line Ap indicates the contour line of the component contributed by the position of the center of gravity P, the broken line Aq indicates the contour line of the component contributed by the position of the maximum deflection point Q, and the broken line Avb indicates the initial ball velocity Vb. Contour lines are shown.
The position at which the sum of these values becomes the maximum, in other words, the hit point of the face surface 1 at which the highest initial velocity of the golf ball is obtained becomes the highest initial velocity point R.
In the present embodiment, when the coordinates of the maximum initial speed point R in the golf club head 10 that satisfies the above-mentioned conditions are (X3, Y3), X3 is in the range of −5 mm to 5 mm, and Y3 is −5 mm. Therefore, the position of the maximum initial speed point R can be matched with or brought close to the center point C of the face surface 1.

Further, when the ball initial velocity Vb when hitting the ball at the maximum initial velocity point R is 100%, and the area on the face surface 1 that is 99% or more of the ball initial velocity Vb is the sweet area, the sweet area is the maximum initial velocity point. Distributed around R. Specifically, the sweet area is distributed along the contour line Avb (FIG. 22A) of the ball initial speed Vb with the maximum initial speed point R as the center.
Therefore, the center of the sweet area coincides with or is close to the center point C of the face surface 1 by making the position of the maximum initial speed point R substantially coincide with or close to the center point C of the face surface 1.
For this reason, the center point C of the face surface 1 where the hit point distribution is the highest matches or is close to the center of the sweet area, which is advantageous in increasing the flight distance.

Further, it is a well-known fact that the initial ball velocity Vb increases as the deflection amount at the maximum deflection point Q increases. Therefore, securing a region with a large deflection amount in the face surface 1 with a larger area is advantageous in increasing the flight distance of the ball.
From this point of view, when the deflection amount at the maximum deflection point Q is 100%, and the area of the face surface where the deflection amount is 95% or more is the deflection area, the deflection area is 150 mm ² or more. This is even more advantageous in increasing the flight distance of the ball.
Further, when the deflection amount at the maximum deflection point Q is 100% and the area of the face surface where the deflection amount is 95% or more is defined as the deflection area, the ratio of the deflection area to the face area is 4% or more. This is even more advantageous in increasing the flight distance of the ball.

Various conventionally known measurement methods can be used as a method for measuring the deflection amount and the deflection area of the face surface 1.
For example, a method described in Japanese Patent Application Laid-Open No. 2004-138484 (a method for measuring a vibration distribution of a striking surface of a golf club head and a method for evaluating a golf club head) can be used.
That is, in this method, the face surface (striking surface) of the golf club head is vibrated in the vertical direction to vibrate the striking surface, and the vibration distribution on the face surface (by a laser vibrometer disposed at a position facing the face surface ( Measure the amplitude distribution).
Then, based on the measurement result of the vibration distribution (amplitude distribution), the amount of deflection at each point is calculated, the amount of deflection at the maximum deflection point is 100%, and the area of the face surface where the amount of deflection is 95% or more is calculated. What is necessary is just to calculate.
More specifically, a rectangular measurement area centered on the center point C of the face surface 1 is set, and a plurality of measurement points are set in this measurement area, and the amplitude distribution is measured for each measurement point.
Thereafter, spline interpolation is performed, the maximum deflection point is calculated, the deflection amount at the maximum deflection point is set to 100%, and the area of the face surface 1 where the deflection amount is 95% or more may be calculated.
As the measurement area, for example, a square of 28 mm each in the toe direction and the heel direction around the center point C of the face surface 1 and 12 mm each in the crown direction and the sole direction around the center point C of the face surface 1. Set the area.
That is, in this example, the measurement area has a square shape of 56 mm in the toe-heel direction and 24 mm in the crown-sole direction.
Further, as the measurement points, for example, the measurement points are set at a pitch of about 0.8 mm in the toe-heel direction and the crown-sole direction.
That is, in this example, all the measurement points in the measurement area are 2048 points.

As described above, according to the present embodiment, the gravity center point P and the maximum deflection point Q are arranged on the face surface 1 in consideration of the velocity distribution of the face surface 1. Therefore, when the golfer actually swings the golf club and hits the ball with the face surface 1, the position of the highest initial velocity point R matches the center point C of the face surface 1 that is near the center of the golfer's hitting point distribution, or Since they can be close to each other, it is advantageous in increasing the flight distance.
In particular, compared to the case where the highest repulsion point measured with the golf club head stationary is arranged near the center point of the face surface without considering the velocity distribution of the face surface 1 as in the prior art described above. The present invention is greatly different in that the center of gravity P and the maximum deflection point Q are arranged in consideration of the velocity distribution of the face surface 1.
By doing so, in the present invention, it is advantageous to make the position of the maximum initial speed point R more precisely match or approach the center point C of the face surface 1, and therefore, the flight distance is increased as compared with the prior art. This is advantageous in achieving this.
Further, the separation distance ΔL between the center of gravity P and the maximum deflection point Q is within a range of 5 to 15 mm, and the angle φ between the straight line LA connecting the center of gravity P and the maximum deflection point Q and the X direction is set to 0 to 70. Since it is within the range of degrees, as shown in FIG. 22B, it is advantageous in expanding the area of the sweet area. The reason will be described below.
In the following description, it is assumed that the restitution coefficient corresponding to the maximum initial speed point R is 0.83 and the restitution coefficient corresponding to 99% of the ball initial speed at the maximum initial speed point R is 0.81.

First, the reason why it is advantageous in enlarging the area of the sweet area that the distance ΔL between the center of gravity P and the maximum deflection point Q is in the range of 5 to 15 mm will be described.
FIG. 23 is a schematic diagram showing the relationship between the separation distance ΔL between the center of gravity P and the maximum deflection point Q and the initial ball speed Vb.
If the separation distance ΔL is less than 5 mm, is the peak of the component in which the position of the center of gravity P contributes to the ball initial speed Vb and the peak of the component in which the position of the maximum deflection point Q contributes to the ball initial speed Vb? Alternatively, the maximum initial speed point R becomes higher because they match, but the area of the high initial speed area where the restitution coefficient is 0.81 or more is narrow.
If the separation distance ΔL is 15 mm or more, the peak of the component in which the position of the center of gravity P contributes to the ball initial speed Vb and the peak of the component in which the position of the maximum deflection point Q contributes to the ball initial speed Vb are too far apart. The initial speed point R decreases and the area of the high initial speed area where the coefficient of restitution becomes 0.81 or more is almost lost.
When the separation distance ΔL is in the range of 5 to 15 mm, the peak of the component where the position of the center of gravity P contributes to the ball initial speed Vb and the peak of the component where the position of the maximum deflection point Q contributes to the ball initial speed Vb are appropriate. Therefore, while ensuring the size of the maximum initial speed point R, it is possible to sufficiently secure the area of the high initial speed area where the restitution coefficient is 0.81 or more.

Next, the reason why the angle φ formed by the straight line LA connecting the centroid point P and the maximum deflection point Q with the X direction is within the range of 0 to 70 degrees is advantageous in expanding the sweet area. explain.
As is apparent from FIGS. 6 to 8, when the golfer actually swings the golf club, the angle α formed by the straight line orthogonal to the contour line indicating the velocity distribution of the face surface 1 and the X axis is as follows. is there.
When the rolling amount shown in FIG. 6 is the minimum: the angle α is 65 degrees When the rolling amount shown in FIG. 7 is an average value: the angle α is 36 degrees When the rolling amount shown in FIG. 8 is the maximum: the angle α is 7 degrees When the golfer actually swings the golf club, the angle α is in the range of 7 degrees to 65 degrees.
Therefore, as shown in FIG. 22B, when the maximum deflection point Q is arranged at a position where the face speed is faster, in other words, the angle φ formed by the straight line LA connecting the center of gravity P and the maximum deflection point Q with the X direction. Is set within the range of the angle α, it is advantageous in increasing the height of the peak of the component that the position of the maximum deflection point Q contributes to the ball initial velocity Vb.
As a result, the height of the mountain of the ball initial speed Vb can be increased, which is advantageous for securing a larger area for the high initial speed, and advantageous for increasing the area of the sweet area.
In the present embodiment, the angle φ is set in the range of 0 to 70 degrees in consideration of variations in the angle α when the golfer actually swings the golf club.

Next, referring to the experimental example, the separation distance ΔL between the center of gravity P and the maximum deflection point Q is within a range of 5 to 15 mm, and the straight line LA connecting the center of gravity P and the maximum deflection point Q is the X direction. It will be specifically described that the angle φ formed is within the range of 0 to 70 degrees, which is advantageous in expanding the sweet area.
The five types of golf club heads 10 in which the range of the separation distance ΔL and the range of the angle φ are set as follows will be described.
Hereinafter, the five types of golf club heads 10 will be described as first to fifth golf club heads.
In the first to fifth golf club heads, the range of the separation distance ΔL and the range of the angle φ are set as follows.
(First Golf Club Head) Separation Distance ΔL: Within 5-15 mm, Angle φ: Within 0-70 ° (Second Golf Club Head) Separation Distance ΔL: Less than 5 mm, Angle φ: 0-70 Within a range of degrees (third golf club head) separation distance ΔL: more than 15 mm, angle φ: Within a range of 0 to 70 degrees (fourth golf club head) separation distance ΔL: within a range of 5-15 mm, angle φ: over 70 degrees (fifth golf club head) separation distance ΔL: within a range of 5 to 15 mm, angle φ: less than 0 degrees FIGS. 24 to 28 correspond to the first golf club heads through 5, respectively. (A) is a front view of the golf club head 10 showing the positions of the center of gravity P, the maximum deflection point Q, and the maximum initial velocity point R, and (B) is the position of the center of gravity P contributing to the initial velocity of the ball. The component and the position of the maximum deflection point Q It is a schematic diagram showing the relationship between the components that contribute to Le initial velocity.

(First golf club head)
As shown in FIG. 24, since the angle φ is in the range of 0 to 70 degrees, the maximum deflection point Q is arranged at a position where the face speed is faster. Therefore, the position of the maximum deflection point Q is advantageous in increasing the height of the peak of the component that contributes to the ball initial speed Vb.
Further, since the separation distance ΔL is in the range of 5 to 15 mm, the high initial speed area (area surrounded by the contour line Avb) in which the coefficient of restitution is 0.81 or more while ensuring the height of the peak of the ball initial speed Vb. It is advantageous for securing a wider area, and is advantageous for expanding the area of the sweet area.

(Second golf club head)
As shown in FIG. 25, even if the angle φ is in the range of 0 to 70 degrees, the separation distance ΔL is less than 5 mm, so the peak of the component in which the position of the center of gravity P contributes to the ball initial speed Vb. And the position of the maximum deflection point Q is close to or coincides with the peak of the component that contributes to the ball initial velocity Vb. Therefore, the maximum initial speed point R becomes higher corresponding to the restitution coefficient 0.83, but the area of the high initial speed area where the restitution coefficient is 0.81 or more is narrow.

(Third golf club head)
As shown in FIG. 26, even if the angle φ is in the range of 0 to 70 degrees, the separation distance ΔL exceeds 15 mm, so that the peak of the component that the position of the center of gravity P contributes to the ball initial speed Vb ( The peak) is separated from the peak of the component in which the position of the maximum deflection point Q contributes to the ball initial speed Vb. Therefore, the maximum initial speed point R is less than the restitution coefficient 0.83, and the area of the high initial speed area where the restitution coefficient is 0.81 or more is narrow.

(4th golf club head)
As shown in FIG. 27, even when the separation distance ΔL is in the range of 5 to 15 mm, the angle φ exceeds 70 degrees, so that the maximum deflection point Q is larger than that of the first golf club head. It is arranged at a position where the face speed is slower. Therefore, the position of the maximum deflection point Q is disadvantageous in increasing the height of the peak of the component that contributes to the ball initial speed Vb. Therefore, the maximum initial speed point R is less than the restitution coefficient 0.83, and the area of the high initial speed area where the restitution coefficient is 0.81 or more is narrow.

(5th golf club head)
As shown in FIG. 28, even when the separation distance ΔL is within the range of 5 to 15 mm, the angle φ is less than 0 degrees, so that the maximum deflection point Q is the face speed compared to the first golf club head. Placed at a later position. Therefore, the position of the maximum deflection point Q is disadvantageous in increasing the height of the peak of the component that contributes to the ball initial speed Vb. Therefore, the maximum initial speed point R is less than the restitution coefficient 0.83, and the area of the high initial speed area where the restitution coefficient is 0.81 or more is narrow.

Based on the results of the first golf club head to 5 described above, the distance ΔL between the center of gravity P and the maximum deflection point Q is within a range of 5 to 15 mm, and the straight line connecting the center of gravity P and the maximum deflection point Q. It is apparent that the angle φ formed by LA with respect to the X direction is in the range of 0 to 70 degrees, which is advantageous in expanding the sweet area.
Enlarging the area of the sweet area in this manner is advantageous in effectively suppressing a decrease in flight distance even if the hit points vary.

(Experimental example)
Next, experimental examples will be described.
The experimental conditions are as follows.
A golf club having the golf club head 10 was swung using a conventionally known swing robot to hit a golf ball.
As shown in FIG. 29, the hit points on the face surface 1 are centered on the center point C of the face surface 1, 9 points at a pitch of 7 mm in the X direction, and 5 points in the Y direction with the center point C as the center. It was a hit point.
In the figure, the intersection of the grid indicates each hit point, and the number in the vicinity of each hit point indicates the hit number assigned to identify each hit point.
The head speed was 40 m / s.
When the golf ball was hit at the center point C, the side spin was ± 200 rpm, and the launch angle was 13.5 ° ± 0.5 °.
The golf ball was a general three-piece ball.
Forty-one hit points were hit three times, the ball initial speed and flight distance were measured to determine the average value, and the initial ball speed and flight distance were determined for each hit point.
The angle α formed by the straight line orthogonal to the contour line representing the velocity distribution of the face surface 1 and the X axis is 65 degrees, and this angle α is the same as that of the golfer with the minimum rolling amount shown in FIG. Is an angle.

FIG. 30 is a table showing experimental results of Experimental Examples 1 to 22.
The evaluation items are the following five.
(1) The area SS1 of the sweet area for the initial ball speed
First, data interpolation (spline interpolation) was performed from the ball initial speed data of 41 hit points to obtain the maximum initial speed point.
Next, data interpolation (spline interpolation) is performed from the ball initial velocity data of 41 hit points, and when the maximum initial velocity point is set to 100%, the area of the face surface 1 that has a ball initial velocity of 99% or more is a sweet related to the ball initial velocity. Sought as an area.
In FIG. 30, the area SS1 (mm ² ) of the sweet area related to the ball initial velocity is described, and the area SS1 is displayed as an index in parentheses in order to easily display the size relationship. This index represents the ratio of the area SS1 of the remaining experimental examples 2 to 22 as a percentage when the area SS1 of the experimental example 1 is set to 100.

(2) Sweet area area SS2 regarding flight distance
First, data interpolation (spline interpolation) was performed from the flight distance data of 41 hit points to obtain the maximum flight distance point.
Next, data interpolation (spline interpolation) is performed from the flying distance data of 41 hit points, and the area of the face surface 1 having a flying distance of 99% or more when the maximum flying distance point is set to 100% is related to the flying distance. Sought as a sweet area.
In FIG. 30, the area SS2 (mm ² ) of the sweet area relating to the flight distance is described, and the area SS2 is displayed as an index in parentheses in order to display the size relationship in an easy-to-understand manner. This index represents the ratio of the area SS2 of the remaining experimental examples 2 to 22 as a percentage when the area SS2 of the experimental example 1 is set to 100.

(3) Flying distance index 15 mm above center point C Data interpolation (spline interpolation) is performed from the flying distance data of 41 hit points, and the flight distance at the hit point 15 mm away from the center point C (in the Y direction) is calculated. Asked.
In FIG. 30, the ratio of the flight distance at the upper 15 mm to the maximum flight distance is expressed as a percentage.

(4) Flying distance index at 20 mm from heel side from center point C Data interpolation (spline interpolation) is performed from flying distance data at 41 hit points, and at a hit point spaced 20 mm from the center point C to the heel 5 side (in the X direction). The flight distance was determined.
In FIG. 30, the ratio of the flight distance at the heel side of 20 mm to the maximum flight distance is displayed as a percentage.

(5) Flying distance index from center point C to toe side 20mm Data interpolation (spline interpolation) is performed from flying distance data of 41 hit points, and at a hit point 20mm away from center point C to toe 8 side (in the X direction). The flight distance was determined.
In FIG. 30, the ratio of the flight distance on the toe side 20 mm to the maximum flight distance is expressed as a percentage.
In FIG. 30, the numerical values in parentheses below the flight distance index 20 mm from the center point C to the toe side are the above-described three flight distance indices (flight distance index 15 mm above the center point C, from the center point C). The flight distance index total value consisting of the sum of the flight distance index on the heel side 20 mm and the flight distance index on the toe side 20 mm from the center point C is shown.

The numerical values made different in each experimental example are as follows.
(1) Deflection area (mm ² )
The area of the face surface 1 at which the deflection amount is 95% or more when the deflection amount at the maximum deflection point Q is 100%.
In Experimental Example 1～9,11～22 was a value exceeding 150 mm ² specified by the present invention a bending area and 153 mm ^2.
In Experimental Example 10, the deflection area was 148 mm ^2, which was less than 150 mm ² defined in the present invention.

(2) Deflection area ratio (%)
When the deflection amount at the maximum deflection point Q is 100% and the area of the face surface 1 where the deflection amount is 95% or more is defined as the deflection area, the ratio of the deflection area to the face area.
In Experimental Examples 1-9 and 11-22, the deflection rate was set to 4.0%, which was 4% or more as defined in the present invention.
In Experimental Example 10, the deflection rate was 3.9%, which was less than 4% defined in the present invention.

(3) Coordinate value of the center of gravity point P X1 (mm), Y1 (mm)
In Experimental Examples 1 to 10, 13 to 18, 20, and 22, X1 = 0.0 to 6.5 mm, Y1 = 0.0 to 7.0 mm, and X1 defined by the present invention is in the range of 0 mm to 10 mm. Thus, Y1 is set to a value in the range of 0 mm to 10 mm.
In Experimental Example 11, X1 = 10.4 mm, Y1 = 6.5 mm, X1 specified in the invention was outside the range of 0 mm to 10 mm, and Y1 was within the range of 0 mm to 10 mm.
In Experimental Example 12, X1 = 4.0 mm, Y1 = 10.5 mm, X1 specified in the invention was in the range of 0 mm to 10 mm, and Y1 was outside the range of 0 mm to 10 mm.
In Experimental Example 19, X1 = −1.0 mm, Y1 = 6.5 mm, X1 specified in the invention was outside the range of 0 mm to 10 mm, and Y1 was within the range of 0 mm to 10 mm.
In Experimental Example 20, X1 = 4.0 mm, Y1 = −1.0 mm, X1 specified in the invention was in the range of 0 mm to 10 mm, and Y1 was outside the range of 0 mm to 10 mm.

(4) Coordinate value of maximum deflection point Q X2 (mm), Y2 (mm)
In Experimental Examples 1 to 16, 19, and 21, X2 = −8.0 mm to 0.0 mm, Y2 = −4.0 mm to 4.0 mm, and X2 specified in the present invention is in the range of −10 mm to 0 mm. , Y2 is set to a value within a range of −10 mm to 10 mm.
In Experimental Example 17, X2 = −10.4 mm, Y2 = 0.0 mm, X2 specified in the present invention is outside the range of −10 mm to 0 mm, and Y2 is within the range of −10 mm to 10 mm. did.
In Experimental Example 18, X2 = −1.5 mm, Y2 = 10.5 mm, X2 specified in the present invention is in the range of −10 mm to 0 mm, and Y2 is outside the range of −10 mm to 10 mm. did.
In Experimental Example 20, X2 = 2.1 mm, Y2 = 1.0 mm, X2 defined in the present invention was outside the range of −10 mm to 0 mm, and Y2 was within the range of −10 mm to 10 mm. .
In Experimental Example 22, X2 = −1.5 mm, Y2 = −10.4 mm, X2 specified in the present invention is in the range of −10 mm to 0 mm, and Y2 is outside the range of −10 mm to 10 mm. It was.

(5) Separation distance ΔL (mm) between the center of gravity P and the maximum deflection point Q
In Experimental Examples 1 to 12, 15, 16, and 18 to 21, ΔL = 5.3 mm to 15.0 mm, and ΔL defined in the present invention was set to a value in the range of 5 to 15 mm.
In Experimental Example 13, ΔL = 16.2 mm, and the separation distance ΔL defined in the present invention was outside the range of 5 to 15 mm.
In Experimental Example 14, ΔL = 4.0 mm, and the separation distance ΔL defined in the present invention was outside the range of 5 to 15 mm.
In Experimental Example 17, ΔL = 15.8 mm, and the separation distance ΔL defined in the present invention was outside the range of 5 to 15 mm.
In Experimental Example 22, ΔL = 17.8 mm, and the separation distance ΔL defined in the present invention was outside the range of 5 to 15 mm.

(6) Angle φ (degree) formed by the straight line connecting the center of gravity P and the maximum deflection point Q with the X direction
In Experimental Examples 1 to 14 and 17, φ = 0.0 ° to 70.0 °, and φ defined in the present invention was set to a value in the range of 0 to 70 °.
In Experimental Example 15, φ = −1.0 °, and the angle φ = 0.0 ° to 70.0 ° specified in the present invention was outside the range.
In Experimental Example 16, φ = 71.3 degrees, and the angle φ = 0.0 degrees to 70.0 degrees defined by the present invention was outside the range.
In Experimental Example 18, φ = −36.0 °, and the angle φ = 0.0 ° to 70.0 ° specified in the present invention was outside the range.
In Experimental Example 19, φ = 85.6 degrees and the angle φ = 0.0 degrees to 70.0 degrees defined in the present invention was outside the range.
In Experimental Example 20, φ = 70.9 degrees, and the angle φ = 0.0 degrees to 70.0 degrees defined in the present invention was outside the range.
In Experimental Example 21, φ was set to −10.3 degrees, and the angle φ according to the present invention was set to a value outside the range of 0.0 degrees to 70.0 degrees.
In Experimental Example 22, φ = 72.0 degrees, and the angle φ = 0.0 degrees to 70.0 degrees defined in the present invention was outside the range.

(7) Coordinate value of maximum initial speed point R X3 (mm), Y3 (mm)
In Experimental Examples 1 to 7 and 10 to 22, X3 = −4.9 mm to 4.9 mm, Y3 = −5.0 mm to 4.5 mm, and X3 specified in the present invention is in the range of −5 mm to 5 mm. , Y3 was set to a value within a range of −5 mm to 5 mm.
In Experimental Example 8, X3 = −6.0 mm, Y3 = 1.2 mm, X3 specified in the present invention is outside the range of −5 mm to 5 mm, and Y3 is within the range of −5 mm to 5 mm. did.
In Experimental Example 9, X3 = −1.1 mm, Y3 = −6.2 mm, X3 specified in the present invention is in the range of −5 mm to 5 mm, and Y3 is outside the range of −5 mm to 5 mm. It was.

Next, experimental examples and evaluation items will be described.
When the indices of the area SS1 and SS2 of the sweet area are evaluated as evaluation items, the following is clear.
Examples 1 to 9 in which the position of the center of gravity P, the position of the maximum deflection point Q, the separation distance ΔL, the angle φ, the deflection area, and the deflection area ratio are values within the range defined by the present invention are the sweet areas Each of the areas SS1 and SS2 has a high index of 78 or more.
On the other hand, the position of the center of gravity P, the position of the maximum deflection point Q, the separation distance ΔL, and the angle φ are values within the ranges defined by the present invention, but the deflection area and the deflection area ratio are defined by the present invention. In Example 10 having a value out of the range, the index of the sweet area area SS1 is 67, and the index of SS2 is 68, which is lower than in Examples 1-9.
In addition, experimental examples 11 to 22 in which any one of the position of the center of gravity P, the position of the maximum deflection point Q, the separation distance ΔL, and the angle φ is outside the range defined in the present invention are as follows. The indexes of SS1 and SS2 are lower than those of Examples 52 to 80 and 52 to 77 and Examples 1 to 9, respectively.
From the above, by setting the position of the center of gravity P, the position of the maximum deflection point Q, the separation distance ΔL, the angle φ, the deflection area, and the deflection area ratio within the range defined by the present invention, It can be seen that it is advantageous in securing a large area.

Further, as the evaluation items, the flight distance index 15 mm above the center point C, the flight distance index 20 mm from the center point C to the heel side, the flight distance index 20 mm from the center point C to the toe side, and the flight distance index total value are seen. The following is clear.
The position of the center of gravity point P, the position of the maximum deflection point Q, the separation distance ΔL, the angle φ, the deflection area, the deflection area ratio are values within the range defined by the present invention, and the position of the maximum initial speed point R is the present invention. In Experimental Examples 1 to 7 that are within the range defined by the above, the above three flight distance indexes are all 99.0% or more, and the total flight distance index value is 297% or more.
The position of the center of gravity P, the position of the maximum deflection point Q, the separation distance ΔL, the angle φ, the deflection area, and the deflection area ratio are values within the range defined by the present invention, but the position of the maximum initial velocity point R is In Experimental Examples 8 and 9, which are outside the range defined by the present invention, the above three flight distance indexes are 97.5% to 98.0%, and the total flight distance index value is 294%. Compared to Examples 1-7, it is slightly lower.
From the above, by setting the position of the maximum initial speed point R within the range defined by the present invention, the hitting point hitting the golf ball is slightly shifted upward from the center point C or toward the heel side or toe side. Even if it exists, it turns out that it is more advantageous in suppressing the fall of a flight distance.
Note that any of the positions of the center of gravity P, the position of the maximum deflection point Q, the separation distance ΔL, the angle φ, the deflection area, and the deflection area ratio is a value outside the range defined in the present invention. No. 22 has a flight distance index total value of 288 to 294%, which is clearly lower than those of Examples 1 to 7. Therefore, it can be seen that it is disadvantageous to suppress the decrease in the flight distance when the hitting point hitting the golf ball is slightly shifted upward from the center point C or toward the heel side or the toe side.

  Next, by setting the positions of the center of gravity P, the maximum deflection point Q, and the maximum initial velocity point R within the ranges defined in the present invention, it is possible to more effectively suppress the flight distance reduction when the hit points vary. Will be further described with reference to experimental examples.

Two types of golf club heads shown below were prepared.
In one golf club head, as shown in FIG. 31, the position of the center of gravity P is X1 = −2 mm, Y = 8 mm, and the position of the center of gravity P in the X direction is shifted to the toe side from the center C. Yes. Hereinafter, for convenience of explanation, the golf club head shown in FIG. 31 is referred to as a “toe-centered gravity head”.
Further, the position of the maximum deflection point Q is X2 = −7 mm, Y2 = 3 mm, X2 defined in the present invention is in the range of −10 mm to 0 mm, and Y2 is in the range of −10 mm to 10 mm. It was set as the value which becomes.
Symbol R0 indicates the highest initial speed point when the velocity distribution of the face surface 1 is not considered, and symbol R1 indicates the highest initial velocity point when the velocity distribution of the face surface 1 is considered.
Here, the position of the maximum initial speed point R considering the speed distribution of the face surface 1 moves to the toe side with respect to the maximum initial speed point R0 not considering the speed distribution of the face surface 1.
The position of the maximum initial speed point R is X3 = 6 mm and Y3 = 0 mm. Therefore, the maximum initial speed point R is offset by 6 mm toward the toe side from the center point C.

In the other golf club head, as shown in FIG. 32, the position of the center of gravity P is X1 = 3.5 mm, Y = 8 mm, and the position of the center of gravity P in the X direction is closer to the heel than the center C. Is biased. Hereinafter, for convenience of explanation, the golf club head shown in FIG. 32 is referred to as a “heel center of gravity head”.
Further, the position of the maximum deflection point Q is the same as in FIG.
Also in this case, the maximum initial speed point R considering the speed distribution of the face surface 1 moves to the toe side with respect to the maximum initial speed point R0 not considering the speed distribution of the face surface 1.
The position of the maximum initial speed point R is X3 = 0 mm and Y3 = 0 mm. Therefore, the maximum initial speed point R coincides with the center point C.

The following experiment was performed using the above-described toe-side center of gravity head and heel center of gravity head.
A golf ball was actually hit at the following hit points at each of the toe-side center of gravity head and the heel center of gravity head, and the flight distance was measured.
As shown in FIG. 29, the hitting points for hitting the golf ball are center point C (spot number 1) and three hit points on the heel side (spot numbers 4, 15, 31) across the center point C along the X direction. ) And 3 hit points on the toe side (spot numbers 8, 23, 28).

The measurement results are shown in FIG.
As is clear from FIG. 33, in the heel center of gravity head, the flight distance has the maximum value at the center point C, and the flight distance decreases as the hit position moves away from the center point C. The toe side and heel side are almost even and balanced.
On the other hand, in the toe-side center-of-gravity head, the flight distance has a maximum hitting point of hitting point number 8, and the flying distance decreases as the hitting point position moves away from the hitting point of hitting point number 8, but the inclination at which the flying distance decreases is The heel side is more prominent than the toe side, and is not balanced.
In particular, the toe-side center-of-gravity head has a flying distance of 4 yards lower at the hit number 15 and 7 yards at the hit number 31 than the heel center of gravity head.

From the above, the following can be said.
As described above, the average hitting point position of the golfer is the center point C. Therefore, it is advantageous in securing the flight distance that the highest initial speed point R is coincident with or close to the center point C. .
As shown in FIGS. 31 and 32, the position of the maximum initial speed point R is affected by the velocity distribution of the face surface 1, in other words, by the influence of rolling due to the golfer's swing, and the velocity distribution is fast from the vicinity of the center of gravity P. Move in the direction.
Therefore, in order to arrange the maximum initial speed point R so as to coincide with or be close to the center point C, it is necessary to arrange the barycentric point P closer to the heel.
That is, in the heel center-of-gravity head shown in FIG. 32, the maximum initial speed point R is arranged so as to coincide with or be close to the center point C, which is advantageous in securing a flight distance. Furthermore, when the hit points vary on the heel side or the toe side, the degree of flight distance reduction on both the heel side and the toe side is balanced, and the reduction of the flight distance due to hit point variations is suppressed. Even more advantageous.
In other words, the position of the maximum initial speed point R is within the range defined by the present invention, that is, the position of the maximum initial speed point R is within the range of -5 mm to 5 mm and Y3 is within the range of -5 mm to 5 mm. By doing so, the above-described effects are exhibited.

On the other hand, in the toe-side center of gravity head shown in FIG. 31, the maximum initial speed point R is arranged to be deviated to the toe side from the center point C, so that when the hit point varies on the heel side or the toe side, The decrease in the flight distance at the hitting point closer to the toe becomes more remarkable than the decrease in the flight distance at the hitting point closer to the toe.
Therefore, the balance of the degree of decrease in the flight distance is biased depending on whether the hit point is closer to the heel or toe, which is disadvantageous in suppressing a decrease in the flight distance due to the hit point variation.

  DESCRIPTION OF SYMBOLS 1 ... Face surface, 5 ... Heel, 6 ... Shaft, 8 ... Toe, 10 ... Golf club head, P ... Center of gravity point, Q ... Maximum deflection point, ΔL ... Center of gravity point P and maximum deflection The separation distance of point Q, φ …… An angle formed by the straight line connecting the center of gravity P and the maximum deflection point Q with the X direction, R …… the maximum initial speed point.

Claims (3)

A golf club head design method comprising:
With the golf club head set along the lie angle, the horizontal direction from the toe side to the heel side of the face surface of the golf club head is the X direction, the vertically upward direction is the Y direction, and the center point of the face surface is Let the coordinates be (0,0),
The coordinates of the barycentric point obtained by projecting the barycentric position of the golf club head perpendicularly to the face surface are (X1, Y1),
When the coordinate of the maximum deflection point in the primary vibration of the face surface is (X2, Y2),
X1 is in the range of 0 mm to 10 mm, Y1 is in the range of 0 mm to 10 mm,
X2 is in the range of −10 mm to 0 mm, Y2 is in the range of −10 mm to 10 mm,
The separation distance between the barycentric point and the maximum deflection point is within a range of 5 to 15 mm,
The angle formed by the straight line connecting the barycentric point and the maximum deflection point with the X direction is in the range of 0 to 70 degrees,
When swinging a golf ball with the face surface by swinging a golf club with the golf club head attached to a shaft,
The hit point of the face surface where the maximum initial speed of the golf ball can be obtained is the maximum initial speed point,
When the coordinate of the maximum initial speed point is (X3, Y3),
X3 was in the range of −5 mm to 5 mm, and Y3 was in the range of −5 mm to 5 mm.
Golf club head design method. When the amount of deflection at the maximum deflection point is 100%, and the area of the face surface at which the deflection amount is 95% or more is defined as a deflection area,
The deflection area was 150 mm ² or more,
The method for designing a golf club head according to claim 1. When the amount of deflection at the maximum deflection point is 100%, and the area of the face surface at which the deflection amount is 95% or more is defined as a deflection area,
The ratio of the deflection area to the face area is 4% or more,
The method for designing a golf club head according to claim 1.

Images