JP2022062896A - Hollow golf club head - Google Patents

Abstract

To secure a high launch angle and increase durability, while increasing repulsion performance.SOLUTION: An area of a head body 12 which is sandwiched between a first plane Pr1 and a second plane Pr2 is defined as a first area A1. A straight line that passes through an intersection γ of an extension line α of a front wall outer surface 34A and an extension line β of a rear wall outer surface 36A and is orthogonal to a horizontal plane HP at any face reference cross section Pf parallel to a face center reference cross section Pfc in the first area A1 is defined as a first reference line Lr1. An angle formed by the extension line α of the front wall outer surface 34A and the first reference line Lr1 in the face reference cross section Pf in the first area A1 is defined as a first angle θ1. An angle formed by the extension line β of the rear wall outer surface 36A and the first reference line Lr1 in the face reference cross section Pf in the first area A1 is defined as a second angle θ2. The second angle θ2 is larger than the first angle θ1.SELECTED DRAWING: Figure 6

Description

Patent Law Article 30, Paragraph 2 Application Applicable On June 8, 2nd year of Reiwa (Korea), the address (https://www.prgrkorea.com/community/topic.php?category=&id=236&page=1&mode= Published on the website of PRGRGR Co., Ltd. (read)

Application for application of Article 30, Paragraph 2 of the Patent Law has been applied. Published on the website of Progear Co., Ltd. at the address (https://www.prgr-golf.com) on July 6, 2nd year of Reiwa (Japan).

The present invention relates to a hollow golf club head.

Improving the initial velocity when hitting a ball with a golf club head is important for improving the flight distance. Therefore, it is necessary to improve the repulsive performance of the golf club head.
Patent Documents 1 and 2 disclose that in a hollow golf club head, a groove portion extending in the toe heel direction is formed in a portion of the sole portion near the face portion.
According to the above technique, the deformation of the groove portion at the time of hitting is promoted to make the face portion more flexible, and the repulsion performance is improved.

Japanese Patent No. 6080916 Japanese Patent No. 5793545

However, although the above-mentioned conventional technique has a certain effect in improving the repulsion performance, there is room for improvement in the following points.
First, the groove portion is elastically deformed at the time of hitting, so that the portion of the face portion near the sole portion is displaced toward the face back side, the face surface is tilted, and the launch angle of the hit ball is lowered, so that the flight distance is improved. There is room for improvement in planning.
Secondly, when the groove portion is elastically deformed at the time of hitting a ball, stress is concentrated on the groove portion, and there is room for improvement in improving durability.
Thirdly, in order to improve the durability while ensuring the elastic deformation at the time of hitting the ball, it is conceivable to increase the wall thickness of the entire groove, but in that case, the weight of the golf club head is increased and the design is made. There is room for improvement in ensuring the degree of freedom.
The present invention has been made in view of such circumstances, and an object of the present invention is to improve the repulsion performance without increasing the weight of the golf club head, to secure a high launch angle, and to have durability. The purpose is to provide a golf club head which is advantageous for improving the performance.

In order to achieve the above object, the present invention includes a head body including a face portion having a vertical height and extending to the left and right, and a sole portion extending rearward from the lower portion of the face portion. A hollow golf club head in which the inside of the head body is a hollow portion, and a groove portion extending in the toe heel direction while being recessed upward is formed in a portion of the sole portion near the face portion, and the groove portion is the groove portion. A front wall portion that protrudes upward from the sole portion near the face portion, and a rear wall portion that protrudes upward from the sole portion closer to the face back than the front wall portion and faces the front wall portion. In a reference state in which the hollow golf club head is provided with a connecting wall portion connecting the upper end of the front wall portion and the upper end of the rear wall portion, and the hollow golf club head is installed according to a predetermined lie angle and loft angle with respect to a horizontal plane. The cross section including the normal line passing through the center point of the face surface and breaking the head body on a plane orthogonal to the horizontal plane is defined as the face center reference cross section, and is parallel to the face center reference cross section to the toe side from the face center reference cross section. The area of the head body sandwiched between the first plane located at a distance of 10 mm and the second plane located at a position 10 mm away from the face center reference cross section on the heel side in parallel with the face center reference cross section. The first region is an extension of the outer surface of the front wall, which is a surface located on the face back side of the front wall portion, and the rear wall portion, which is an arbitrary cross section parallel to the face center reference cross section in the first region. The first reference line is a straight line that passes through the intersection with the extension line of the outer surface of the rear wall, which is a surface located on the face portion side, and is orthogonal to the horizontal plane. When the angle formed by the line is the first angle θ1 and the angle formed by the extension line of the outer surface of the rear wall and the first reference line in the arbitrary cross section is the second angle θ2, the angle is higher than the first angle θ1. The second angle θ2 is large.

According to the present invention, by satisfying the condition that the first angle θ1 <the second angle θ2, the amount of deflection is appropriately suppressed while suppressing the excessive amount of deflection of the portion of the face portion near the sole portion at the time of hitting. Since it can be secured, the repulsion performance can be improved, and the displacement of the face surface near the sole portion at the time of hitting can be suppressed to be excessive, so that the launch angle can be secured high, and the initial velocity and flight distance of the hit ball can be secured. It is advantageous in improving the above.
Further, according to the present invention, by satisfying the condition that the first angle θ1 <the second angle θ2, the stress concentration in the groove portion and the portion near the sole portion of the face portion is relaxed, so that the durability is improved. It will be advantageous on.
In addition, if the wall thickness of the entire groove is increased in order to improve durability while ensuring elastic deformation at the time of hitting a ball, the weight of the hollow golf club head increases, which has the disadvantage of reducing the degree of freedom in design. On the other hand, in the present invention, since the condition that the first angle θ1 <the second angle θ2 is satisfied can be satisfied, it is possible to avoid an increase in the weight of the hollow golf club head, which is advantageous in ensuring the degree of freedom in design.

It is a front view which looked at the golf club head which concerns on embodiment from the front of the face surface. It is the A arrow view of FIG. It is a B arrow view of FIG. It is the C arrow view of FIG. It is sectional drawing of the face center reference cross section Pfc which was broken in the plane X of FIG. It is sectional drawing of the face center reference cross section Pfc which was broken in the plane X of FIG. 1, and depicts the lower part of a face part and the front part of a sole part. (A) is a cross-sectional view showing a deformed state of the golf club head of the comparative example in which the first angle θ1> the second angle θ2, and (B) is a contour diagram showing the distribution of stress in the cross section of the golf club head at the time of hitting a ball. be. (A) is a cross-sectional view showing a deformed state of the golf club head of the present invention in which the first angle θ1 <second angle θ2, and (B) is a contour diagram showing the distribution of stress in the cross section of the golf club head at the time of hitting a ball. be. It is 1st explanatory drawing which shows the method of defining the center point Pc of a face surface. It is a 2nd explanatory drawing which shows the method of defining the center point Pc of a face surface. It is a 3rd explanatory view which shows the method of defining the center point Pc of a face surface. It is a 4th explanatory view which shows the method of defining the center point Pc of a face surface. It is sectional drawing of the golf club head which shows the relationship between the center of gravity point G0 of a golf club head, and the center of gravity point FG on a face surface. It is a front view of the golf club head explaining the definition of the contour line I of a face surface. It is sectional drawing of the golf club head explaining the definition of the contour line I of a face surface. It is a front view of the golf club head explaining the definition of the center point Pc of a face surface. It is a figure which shows the evaluation result of the experimental example under condition 1. It is a figure which shows the evaluation result of the experimental example under condition 2. It is a figure which shows the evaluation result of the experimental example under condition 3. It is a figure which shows the evaluation result of the experimental example under condition 4. It is a figure which shows the evaluation result of the experimental example under condition 5. It is a figure which shows the evaluation result of the experimental example under condition 6. It is a figure which shows the evaluation result of the experimental example under condition 7. It is a figure which shows the evaluation result of the experimental example under condition 8.

Next, an embodiment of the present invention will be described.
As shown in FIGS. 1 to 5, in the present embodiment, the case where the hollow golf club head 10 is a utility or a fairway wood for hitting a ball placed on the ground will be described, but the present invention is hollow. Of course, it can also be applied to wood type golf club heads (drivers) or hollow irons.
The hollow golf club head 10 includes a head body 12, and the head body 12 is mainly made of a metal material.
As the metal material, for example, one kind or two or more kinds such as stainless steel, maraging steel, pure titanium, titanium alloy or aluminum alloy are used.
It goes without saying that the head body 12 may have a composite structure in which the crown portion 16 and / or the sole portion 18 is made of carbon fiber reinforced resin (CFRP) and the remaining portion is made of the above metal material. be.
The head body 12 includes a face portion 14, a crown portion 16, a sole portion 18, and a side portion 20.
The face portion 14 has a vertical height and extends to the left and right.
The crown portion 16 has a wall thickness smaller than that of the face portion 14 and extends rearward from the upper portion of the face portion 14.

The sole portion 18 extends rearward from the lower portion of the face portion 14.
The side portion 20 extends between the crown portion 16 and the sole portion 18 through the face back 26 between the toe 22 side edge and the heel 24 side edge of the face portion 14.
As shown in FIG. 5, the head main body 12 has a hollow structure in which the inside surrounded by the face portion 14, the crown portion 16, the sole portion 18, and the side portion 20 is a hollow portion 28.
The outer surface exposed to the outside of the face portion 14 is the face surface 14A for hitting the ball, and the inner surface of the face portion 14 facing the hollow portion 28 is the face inner surface 14B.
The outer surface exposed to the outside of the crown portion 16 is the crown surface 16A, and the inner surface of the crown portion 16 facing the hollow portion 28 is the crown inner surface 16B.
As shown in FIG. 1, the crown portion 16 is provided with a hosel 30 connected to the shaft S on the face surface 14A side and at a position closer to the heel 24, and the golf club 100 is connected to the hosel 30 by connecting the shaft S. Is configured.
The outer surface exposed to the outside of the sole portion 18 is the sole surface 18A, and the inner surface of the sole portion 18 facing the hollow portion 28 is the sole inner surface 18B.
In FIGS. 2 to 5, reference numeral 19 indicates a leading edge which is a boundary between the face portion 14 (face surface 14A) and the sole portion 18 (sole surface).

Next, a method of defining the center point Pc of the face surface 14A will be described.
The center point Pc of the face surface 14A is the geometric center of the face surface 14A, and various conventionally known methods of defining the center point Pc include the first defining method and the second defining method exemplified below. The method can be adopted.

[A] First method of defining the center point Pc of the face surface 14A:
When the boundary between the face surface 14A and the portion of the other hollow golf club head 10 is clear, in other words, it is a method of defining the center point Pc when the peripheral edge of the face surface 14A is specified by a ridgeline. In this case, the face surface 14A is clearly defined. 9 to 12 are explanatory views showing a method of defining the center point Pc of the face surface 14A.

(1) First, as shown in FIG. 9, the hollow golf club head 10 is placed on the horizontal surface HP so that the lie angle and the face angle become specified values. The state of the hollow golf club head 10 at this time is used as a reference state. The set values of the lie angle and the face angle are, for example, the values described in the product catalog.

(2) Next, the temporary center point c0 in the direction connecting the crown portion 16 and the sole portion 18 is obtained.
That is, as shown in FIG. 9, a perpendicular line f0 that intersects the approximate center point of a line parallel to the horizontal plane HP connecting the toe 22 and the heel 24 (hereinafter referred to as a horizontal line) is drawn.
The midpoint between the a0 point where the perpendicular line f0 and the upper edge of the face surface 14A intersect and the b0 point where the perpendicular line f0 and the lower edge of the face surface 14A intersect is defined as a temporary center point c0.

(3) Next, as shown in FIG. 10, a horizontal line g0 passing through the temporary center point c0 is drawn.
(4) Next, as shown in FIG. 11, at the d0 point where the horizontal line g0 and the edge of the face surface 14A on the toe 22 side intersect, and the e0 point where the horizontal line g0 and the edge of the face surface 14A on the heel 24 side intersect. The midpoint is the temporary center point c1.

(5) Next, as shown in FIG. 12, a perpendicular line f1 passing through the temporary center point c1 is drawn, and the perpendicular line f1 and the lower edge of the face surface 14A intersect with the perpendicular line f1 and the upper edge of the face surface 14A. Let the midpoint of the b1 point where the two intersect is the temporary center point c2.
Here, if the temporary center points c1 and c2 match, that point is defined as the center point Pc of the face surface 14A.
If the temporary center points c1 and c2 do not match, the steps (2) to (5) are repeated.
Since the face surface 14A has a curved surface, the length of the horizontal line g0 and the lengths of the perpendicular lines f0 and f1 when the midpoint of the horizontal line g0 and the midpoint of the perpendicular lines f0 and f1 are obtained is the curved surface of the face surface 14A. Along the length shall be used.
The face center line CL is defined by a straight line that passes through the center point Pc and extends in a direction orthogonal to the toe heel direction.

[B] A second method for defining the center point Pc of the face surface 14A:
Next, the definition of the center point Pc when the peripheral edge of the face surface 14A and the portion of the other hollow golf club head 10 are connected by a curved surface and the face surface 14A cannot be clearly defined will be described.

As shown in FIG. 13, the hollow golf club head 10 is hollow, the reference numeral G0 indicates the center of gravity point of the hollow golf club head 10, and the reference numeral Lp is a straight line connecting the center of gravity point G0 and the center of gravity point FG on the face surface 14A. In other words, the straight line Lp is a perpendicular line of the face surface 14A passing through the center of gravity point G0.
That is, the point where the center of gravity point G0 of the hollow golf club head 10 is projected onto the face surface 14A is the center of gravity point FG on the face surface 14A.
Here, as shown in FIG. 14, consider a large number of planes H1, H2, H3, ..., Hn including a straight line Lp connecting the center of gravity point G0 and the center of gravity point FG on the face surface 14A.

As shown in FIG. 15, the radius of curvature r0 of the outer surface of the hollow golf club head 10 is measured in the cross section when the hollow golf club head 10 is broken along the planes H1, H2, H3, ..., Hn.
When measuring the radius of curvature r0, it is treated as if there is no face line, punch mark, etc. on the face surface 14A.
The radius of curvature r0 is continuously measured outward (upward and downward in FIG. 15) from the center point Pc of the face surface 14A.
Then, in the measurement, the portion where the radius of curvature r0 is first or less than a predetermined value is defined as the contour line I representing the peripheral edge of the face surface 14A.
The predetermined value is, for example, 200 mm.
A region surrounded by contour lines I determined based on a number of planes H1, H2, H3, ..., Hn is defined as the face surface 14A, as shown in FIGS. 14 and 15.

Next, as shown in FIG. 16, the hollow golf club head 10 is placed on a horizontal ground (horizontal plane HP) so that the lie angle and the face angle become specified values.
The straight line LT passes through the toe 22 side point PT of the face surface 14A and extends in the vertical direction.
The straight line LH passes through the heel 24 side point PH of the face surface 14A 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 numeral Pu indicates an upper point of the face surface 14A, and reference numeral Pd is a lower point of the face surface 14A. 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 Pc is defined by the midpoint of the line segment connecting the upper point Pu and the lower point Pd.

Next, the provisions of each part of the hollow golf club head 10 will be described in detail.
As shown in FIGS. 1 to 5, the hollow golf club head 10 is set in a reference state in which the hollow golf club head 10 is installed according to a predetermined lie angle and loft angle with respect to the horizontal plane HP. In the following, the reference state of the hollow golf club head 10 is simply referred to as a “reference state”.
As shown in FIGS. 1 and 5, in the reference state, a cross section obtained by breaking the head body 12 on a plane X including a normal line passing through the center point Pc of the face surface 14A and orthogonal to the horizontal plane HP is referred to as a face center reference cross section Pfc. do. In other words, the face center reference cross section Pfc is a cross section in which the head body 12 is broken at a plane X including the face center line CL and orthogonal to the horizontal plane HP in the reference state.
Further, a cross section obtained by breaking the head body 12 on an arbitrary plane parallel to the face center reference cross section Pfc is referred to as a face reference cross section Pf. Therefore, the face reference cross section Pf includes the face center reference cross section Pfc.

(Groove)
As shown in FIGS. 3, 5, and 6, a groove portion 32 extending in the toe heel direction while being recessed upward is formed in a portion of the sole portion 18 near the face portion 14, and the wall portion constituting the groove portion 32 is a hollow portion. It protrudes to the 28 side.
The groove portion 32 secures the amount of deflection of the face portion 14 by promoting elastic deformation when the ball is hit on the face surface 14A, and the groove portion 32 provides the repulsive performance of the hollow golf club head 10. Can be enhanced.

As shown in FIGS. 5 and 6, in the present embodiment, the wall portion constituting the groove portion 32 includes a front wall portion 34, a rear wall portion 36, and a connecting wall portion 38.
The front wall portion 34 projects upward from the portion of the sole portion 18 near the face portion 14.
In the present embodiment, as shown in FIG. 6, the front wall portion 34 extends upward on the first reference line Lr1, which will be described later, or is displaced toward the face back 26 as it goes upward.
Here, the surface of the front wall portion 34 located on the face back 26 side is referred to as the front wall outer surface 34A.

The rear wall portion 36 projects upward from the sole portion 18 closer to the face back 26 than the front wall portion 34 and faces the front wall portion 34.
In the present embodiment, the rear wall portion 36 is displaced toward the face portion 14 toward the upper side.
Here, the surface of the rear wall portion 36 located on the face portion 14 side is referred to as the rear wall outer surface 36A.

The connection wall portion 38 connects the upper end of the front wall portion 34 and the upper end of the rear wall portion 36.
Here, the surface facing downward of the connecting wall portion 38 is referred to as the connecting wall outer surface 38A.
Further, in any face reference cross section Pf, the portion where the outer surface 38A of the connecting wall is separated from the horizontal plane HP most upward is defined as the deepest portion 40 of the groove portion 32.
Further, the shape of the connecting wall portion 38 may be any shape as long as it smoothly connects the upper end of the front wall portion 34 and the upper end of the rear wall portion 36 so that stress is not concentrated at the time of hitting the ball, as shown in FIG. , The connecting wall portion 38 (connecting wall outer surface 38A) may have a curved surface shape, or the connecting wall portion 38 (connecting wall outer surface 38A) may be opposed to the upper end of the front wall portion 34 and the upper end of the rear wall portion 36. It may have a flat surface that is smoothly connected.

Further, the portion of the sole portion 18 connecting the lower end of the front wall portion 34 and the leading edge 19 is referred to as the front end sole wall 1802.
In the present embodiment, the case where the rear wall portion 36 has a shape as shown by the solid line in FIG. 5 will be described, but as shown by the imaginary line in FIG. 5, the sole portion 18 is located at the rear portion of the rear wall portion 36. Of course, the present invention can be applied even if the weight portion 39 is provided integrally with the weight portion 39.

(First angle θ1, second angle θ2)
As shown in FIG. 3, the plane located parallel to the face center reference cross section Pfc and 10 mm away from the face center reference cross section Pfc on the toe 22 side is defined as the first plane Pr1, and is parallel to the face center reference cross section Pfc and the face center. The plane located at a position 10 mm away from the reference cross section Pfc on the heel side is referred to as a second plane Pr2.
The region of the head body 12 sandwiched between the first plane Pr1 and the second plane Pr2 is referred to as the first region A1.
As shown in FIG. 6, at an arbitrary face reference cross section Pf parallel to the face center reference cross section Pfc in the first region A1, the intersection γ between the extension line α of the front wall outer surface 34A and the extension line β of the rear wall outer surface 36A is set. The straight line orthogonal to the horizontal plane HP is defined as the first reference line Lr1.
The angle formed by the extension line α of the front wall outer surface 34A and the first reference line Lr1 in the face reference cross section Pf in the first region A1 is defined as the first angle θ1.
The angle formed by the extension line β of the rear wall outer surface 36A and the first reference line Lr1 in the face reference cross section Pf in the first region A1 is defined as the second angle θ2.
In the present embodiment, the first angle θ1 <the second angle θ2.
In the following, "arbitrary face reference cross section Pf" including both "arbitrary face reference cross section Pf in the first region A1" and "arbitrary face reference cross section Pf in a portion other than the first region A1". I will say that.
When specifying the "face reference cross section Pf" corresponding to the "first region A1" in the "arbitrary face reference cross section Pf", it is described as "arbitrary face reference cross section Pf in the first region A1". And.

Here, with reference to FIGS. 7 and 8, the influence of the magnitude relationship between the first angle θ1 and the second angle θ2 of the groove portion 32 on the deformation amount and the stress distribution of the groove portion 32 at the time of hitting a ball will be described.
In the following, a hollow golf club head that does not satisfy the provisions of the present invention of a first angle θ1 <a second angle θ2 will be referred to as a hollow golf club head 10'of the comparative example, and the hollow golf club head 10'of this comparative example and the first. A hollow golf club head 10 satisfying the provision of the present invention of angle θ1 <second angle θ2 will be described.
FIG. 7A shows the amount of deformation of the hollow golf club head 10'of the comparative example at the time of hitting, the imaginary line shows the state before hitting, and the solid line shows the state at the time of hitting.
FIG. 7B is a contour diagram showing the stress distribution at the time of hitting in the above comparative example in a simplified manner. The fine part of the hatching shows the part with the highest stress, and the coarse part of the hatching shows the part with the next highest stress. Shows.
FIG. 8A shows the amount of deformation of the hollow golf club head 10 of the present embodiment at the time of hitting, and FIG. 8B shows the stress distribution at the time of hitting the ball of the present embodiment.
Note that FIGS. 7 (B) and 8 (B) show the stress distribution in two stages in order to simplify the drawing, but in the actual contour diagram, the higher the stress, the cooler the color to be displayed. The stress distribution is expressed in multiple stages by changing from to warm colors.

As is clear from comparing FIGS. 7 (A) and 8 (A), the present embodiment (first angle θ1 <second angle θ1) is compared with the comparative example (first angle θ1> second angle θ2). In θ2), the amount of elastic deformation of the front wall portion 34 toward the face back 26 side at the time of hitting is suppressed, and therefore the amount of deformation of the face portion 14 near the sole portion 18 toward the face back 26 side is suppressed. You can see that it has been done.
As is clear from comparing FIGS. 7 (B) and 8 (B), the present embodiment (first angle θ1 <second angle θ1) is compared with the comparative example (first angle θ1> second angle θ2). In θ2), the area where high stress is distributed is small in the portion extending from the lower part of the face portion 14 to the front wall portion 34 and the portion of the connecting portion, and therefore, in the groove portion 32 and the portion of the face portion 14 near the sole portion 18. It can be seen that the stress concentration is relaxed.

Therefore, in the hollow golf club head 10 of the present embodiment as compared with the hollow golf club head 10'of the comparative example, the sole of the face portion 14 at the time of hitting is satisfied by satisfying the condition that the first angle θ1 <the second angle θ2. Since the amount of deflection can be appropriately secured while suppressing the excessive amount of deflection at the portion near the portion 18, the repulsion performance can be improved, and the face surface 14A near the sole portion 18 at the time of hitting a ball can be improved. Since it is possible to suppress excessive displacement, a high launch angle can be secured, which is advantageous in improving the initial velocity and flight distance of the hit ball.
Further, in the hollow golf club head 10 of the present embodiment as compared with the hollow golf club head 10'of the comparative example, the soles of the groove portion 32 and the face portion 14 are provided by satisfying the condition that the first angle θ1 <the second angle θ2. Since the stress concentration in the portion near the portion 18 is relaxed, it is advantageous in improving the durability.
Further, if the wall thickness of the entire groove portion 32 is increased in order to improve the durability while ensuring the elastic deformation at the time of hitting the ball, the weight of the hollow golf club head 10 is increased, which is disadvantageous in that the degree of freedom in design is reduced. However, in the present embodiment, since the condition that the first angle θ1 <the second angle θ2 is satisfied can be satisfied, it is possible to avoid an increase in the weight of the hollow golf club head 10 and to secure the degree of freedom in design. It becomes advantageous in.

Further, as shown in FIG. 6, in the present embodiment, the front wall portion 34 extends upward on the first reference line Lr1 or is displaced toward the face back 26 as it goes upward, and the first angle θ1 Is 0 ° or more and less than 30 °.
When the first angle θ1 is within the above range, it is more advantageous in ensuring durability while ensuring repulsion performance and launch angle.
When the first angle θ1 is less than the above range, the deformation of the groove portion 32 becomes too large, so that the repulsion performance can be ensured, but the effect of securing the launch angle is lowered and the effect of ensuring durability is lowered.
When the first angle θ1 exceeds the above range, the deformation of the groove portion 32 becomes too small, so that the effect of ensuring the launch angle and the effect of ensuring durability can be obtained, but the effect of ensuring the repulsion performance is lowered.

Further, as shown in FIG. 6, in the present embodiment, the rear wall portion 36 is displaced toward the face portion 14 as it goes upward, and the second angle θ2 is 15 ° or more and 30 ° or less.
When the second angle θ2 is within the above range, it is more advantageous in ensuring durability while ensuring repulsion performance and launch angle.
When the second angle θ2 is less than the above range, the deformation of the groove portion 32 becomes too large, so that the repulsion performance can be ensured, but the effect of securing the launch angle is lowered and the effect of ensuring durability is lowered.
When the second angle θ2 exceeds the above range, the deformation of the groove portion 32 becomes too small, so that the effect of ensuring the launch angle and the effect of ensuring durability can be obtained, but the effect of ensuring the repulsion performance is lowered.

(Range of 1st distance L, 2nd distance Lt, 3rd distance Lh)
Further, as shown in FIG. 6, the deepest portion 40 of the groove portion 32 in the face center reference cross section Pfc is defined as the first deepest portion 40A, and the height of the first deepest portion 40A from the horizontal plane HP is defined as the first distance L0.
As shown in FIG. 3, the deepest portion 40 in the cross section broken by the third plane Pr3 located at a position parallel to the face center reference cross section Pfc and 20 mm away from the face center reference cross section Pfc is the second deepest portion 40B. As a result, the height of the second deepest portion 40B from the plane passing through the lowermost end of the sole surface 18A and parallel to the horizontal plane HP in the cross section broken by the third plane Pr3 is defined as the second distance Lt.
As shown in FIG. 3, the deepest portion 40 in the cross section broken by the fourth plane Pr4 located at a position parallel to the face center reference cross section Pfc and 20 mm away from the face center reference cross section Pfc is defined as the third deepest portion 40C. The height of the third deepest portion 40C from the plane passing through the lowermost end of the sole surface 18A and parallel to the horizontal plane HP in the cross section broken by the fourth plane Pr4 is defined as the third distance Lh.
At this time, the following equations (1) and (2) were satisfied.
0.5L0 ≤ Lt ≤ 1.5L0 (1)
0.5L0 ≤ Lh ≤ 1.5L0 (2)
When the second distance Lt and the third distance Lh satisfy the ranges of the above equations (1) and (2), it is advantageous in improving the durability while ensuring the repulsion performance.
When the second distance Lt and the third distance Lh are less than the ranges of the above equations (1) and (2), the elastic deformation of the groove portion 32 at the time of hitting the ball becomes small, so that the effect of ensuring the repulsion performance is lowered.
If the second distance Lt and the third distance Lh exceed the ranges of the above equations (1) and (2), the elastic deformation of the groove portion 32 at the time of hitting the ball becomes excessive, so that the repulsion performance can be ensured, but the durability is improved. The effect of securing is reduced.

(The magnitude relationship between the first distance L0, the second distance Lt, and the third distance Lh)
Further, any of the following conditions A to F that define the magnitude relationship between the first distance L0, the second distance Lt, and the third distance Lh is satisfied as described below.
Condition A: The third distance Lh is larger than the first distance L0 and the second distance Lt.
Condition B: The second distance Lt is larger than the first distance L0 and the third distance Lh.
Condition C: The third distance Lh is smaller than the first distance L0 and the second distance Lt.
Condition D: The second distance Lt is smaller than the first distance L0 and the third distance Lh.
Condition E: The first distance L0 is larger than the second distance Lt and the third distance Lh.
Condition F: The first distance L0 is smaller than the second distance Lt and the third distance Lh.
When any of the above conditions A to F is satisfied, the distance of the deepest portion 40 of the entire groove portion 32 from the horizontal plane HP can be optimized, which is more advantageous in achieving both resilience performance and durability.
That is, the condition A corresponds to, for example, a case where the first distance L0 and the second distance Lt have substantially the same value, and the third distance Lh is larger than the same value.
Condition B corresponds to, for example, a case where the first distance L0 and the third distance Lh have substantially the same value, and the second distance Lt is larger than the same value.
The condition C corresponds to a case where the first distance L0 and the second distance Lt have substantially the same value and the third distance Lh is smaller than the same value.
The condition D corresponds to a case where the first distance L0 and the third distance Lt have substantially the same value and the second distance Lh is smaller than the same value.
The condition E corresponds to a case where the first distance L0 is larger than the second distance Lt and the third distance Lh.
The condition F corresponds to the case where the first distance L0 is smaller than the second distance Lt and the third distance Lh.
On the other hand, when none of the conditions A to F is satisfied and all of the first distance L0, the second distance Lt, and the third distance Lh are uniformly increased, the rigidity of the entire groove portion 32 is lowered. Since the elastic deformation of the groove portion 32 at the time of hitting the ball becomes excessive, the repulsive performance can be ensured, but the effect of ensuring the durability is reduced.
Further, when none of the conditions A to F is satisfied and all of the first distance L0, the second distance Lt, and the third distance Lh are uniformly reduced, the rigidity of the entire groove portion 32 increases, so that the ball is hit. Since the elastic deformation of the groove portion 32 is too small, the durability can be ensured, but the effect of ensuring the repulsion performance is reduced.

(Thickness t1 of the connecting wall portion 38 in the deepest portion 40, wall thickness t4 of the rear wall portion 36)
Further, as shown in FIG. 6, in an arbitrary face reference cross section Pf, the wall thickness t4 of the rear wall portion 36 is larger than the wall thickness t1 of the connection wall portion 38 in the deepest portion 40.
When the above conditions are satisfied, stress is concentrated on the connection wall portion 38 at the deepest portion 40 at the time of hitting the ball, so that elastic deformation of the connection wall portion 38 at the deepest portion 40 can be promoted, which is more advantageous in improving the repulsion performance.
If the above conditions are not satisfied, the effect of stress concentration on the connection wall portion 38 at the deepest portion 40 at the time of hitting is reduced, the effect of promoting elastic deformation of the connection wall portion 38 at the deepest portion 40 is reduced, and the repulsion performance is improved. The effect of causing is reduced.

(Maximum wall thickness t2 of front end sole wall 1802)
Further, as shown in FIG. 6, the maximum wall thickness of the front end sole wall 1802 is t2 in an arbitrary face reference cross section Pf.
The maximum wall thickness t2 of the front end sole wall 1802 is larger than the wall thickness t1 of the connecting wall portion 38 in the deepest portion 40.
When the wall thickness t1 <maximum wall thickness t2, it is more advantageous in ensuring durability while improving the resilience performance.
When the wall thickness t1> the maximum wall thickness t2, stress is concentrated on the front end sole wall 1802 at the time of hitting a ball, and the effect of ensuring durability is reduced.
When the wall thickness t1 = the maximum wall thickness t2, it is necessary to increase the wall thickness t1 and the maximum wall thickness t2 in order to secure durability, and the rigidity is increased, so that elastic deformation of the groove portion 32 is promoted at the time of hitting a ball. The effect of improving the repulsion performance is reduced.

(Thickness t3 of the front wall portion 34)
Further, as shown in FIG. 6, in an arbitrary face reference cross section Pf, the wall thickness t3 of the front wall portion 34 is equal to or larger than the wall thickness t1 of the connection wall portion 38 in the deepest portion 40, and the wall thickness of the front end sole wall 1802. The maximum wall thickness is t2 or less.
That is, t1 ≦ t3 ≦ t2.
When the wall thickness t3 of the front wall portion 34 is within the above range, it is more advantageous in ensuring durability while improving the repulsion performance.
When the wall thickness t3 of the front wall portion 34 is less than the above range, stress is concentrated on the front wall portion 34 at the time of hitting a ball, and the effect of improving durability is reduced.
When the wall thickness t3 of the front wall portion 34 exceeds the above range, the rigidity is increased, so that the effect of promoting elastic deformation of the groove portion 32 at the time of hitting is reduced, and the effect of improving the repulsion performance is reduced.

(Thickness t1 of the connecting wall portion 38 in the deepest portion 40)
In any face reference cross section Pf, the wall thickness t1 of the connecting wall portion 38 in the deepest portion 40 is 1.0 mm or more and 1.5 mm or less.
When the wall thickness t1 of the connecting wall portion 38 in the deepest portion 40 is within the above range, it is more advantageous in ensuring durability while improving the repulsion performance.
If the wall thickness t1 of the connecting wall portion 38 in the deepest portion 40 is less than the above range, the elastic deformation of the connecting wall portion 38 in the deepest portion 40 becomes excessive at the time of hitting a ball, so that the effect of improving durability is reduced.
If the wall thickness t1 of the connecting wall portion 38 in the deepest portion 40 exceeds the above range, the elastic deformation of the connecting wall portion 38 in the deepest portion 40 becomes too small at the time of hitting a ball, so that the effect of improving the repulsion performance is reduced.

(Maximum wall thickness t2 of front end sole wall 1802)
In any face reference cross section Pf, the maximum wall thickness t2 of the front end sole wall 1802 is 1.2 mm or more and 2.5 mm or less.
When the maximum wall thickness t2 of the front end sole wall 1802 is within the above range, it is more advantageous in ensuring durability while improving the resilience performance.
When the maximum wall thickness t2 of the front end sole wall 1802 is less than the above range, stress is excessively concentrated on the front end sole wall 1802 at the time of hitting a ball, and the effect of improving durability is reduced.
When the maximum wall thickness t2 of the front end sole wall 1802 exceeds the above range, stress is excessively concentrated on the front wall portion 34 connected to the front end sole wall 1802, and the effect of improving durability is reduced.

(Deepest distance Lx)
In any face reference cross section Pf, when the height of the deepest portion 40 from the horizontal plane HP is the deepest portion distance Lx, the deepest portion distance Lx is 3 mm or more and 20 mm or less.
When the deepest distance Lx is within the above range, it is more advantageous in ensuring durability while improving the repulsion performance.
When the deepest distance Lx is less than the above range, the depth of the groove 32 becomes too small at the time of hitting the ball, so that the elastic deformation of the groove 32 becomes small and the effect of improving the repulsion performance decreases.
If the deepest distance Lx exceeds the above range, the depth of the groove 32 becomes excessive at the time of hitting, so that the effect of securing the launch angle is reduced and the effect of ensuring durability is reduced.

(Groove length W)
As shown in FIG. 3, the groove length W of the groove portion 32 along the toe heel direction is 40 mm or more and 80 mm or less.
When the groove length W is within the above range, it is more advantageous in ensuring durability while improving the repulsion performance.
When the groove length W is less than the above range, the elastic deformation of the groove portion 32 is small at the time of hitting a ball, and the effect of improving the repulsion performance is reduced.
If the groove length W exceeds the above range, the rigidity of the groove portion 32 becomes too low, so that the elastic deformation of the groove portion 32 becomes excessive at the time of hitting the ball, the effect of securing the launch angle is reduced, and the effect of ensuring durability is obtained. descend.

(Shortest distance Lf connecting the deepest portion 40 and the inner surface 14B of the face)
As shown in FIG. 6, in an arbitrary face reference cross section Pf, the shortest distance Lf connecting the deepest portion 40 and the face inner surface 14B is 4 mm or more and 10 mm or less.
When the shortest distance Lf connecting the deepest portion 40 and the inner surface 14B of the face is within the above range, it is more advantageous in ensuring durability while improving the repulsion performance.
If the shortest distance Lf connecting the deepest portion 40 and the inner surface 14B of the face is less than the above range, the distance between the groove portion 32 and the face portion 14 is too short, so that the impact force applied to the groove portion 32 at the time of hitting the ball becomes excessive and durability is ensured. The effect is reduced.
If the shortest distance Lf connecting the deepest portion 40 and the inner surface 14B of the face exceeds the above range, the distance between the groove portion 32 and the face portion 14 is too long. Decreases.

Further, the present invention is mainly applied to a utility, fairway wood, in which the volume of the head body 12 is 100 cc or more and 200 cc or less, particularly for hitting a ball placed on the ground. Of course, it can be applied to a driver having a volume of more than 200 cc and a hollow iron having a head body 12 having a volume of less than 100 cc.

Hereinafter, experimental examples of the present invention will be described.
17 to 24 are views showing experimental results of the hollow golf club head 10 according to the present invention.
A hollow golf club head 10 as a sample was prepared for each experimental example, and the following three evaluation items were measured to obtain an index (evaluation point), and a total score of the three indexes was obtained.

(1) Repulsion performance (initial speed)
The resilience performance was evaluated at the initial velocity.
A golf club equipped with a hollow golf club head 10 was installed in a swing robot, an actual hit test was performed under the following conditions, and the average value of the initial velocity at 9 RBIs was evaluated as an index. The index of Experimental Example A corresponding to the comparative example is set to 100, and the larger the index, the faster the initial velocity and the better the evaluation.
Head speed: 40m / s
The hitting positions were the following 9 hitting points in total, and the ball was hit 5 times at each hitting point.
Three dots: a center point Pc of the face surface 14A, a point 7 mm away from the center point Pc in the toe direction on a straight line passing through the center point Pc and orthogonal to the face center line CL, and a point 7 mm away in the heel direction.
A point separated from the center point Pc by 5 mm in the crown portion 16 direction on the face center line CL, and a point separated from the above point by 7 mm in the toe direction on the upper 5 mm line passing through this point and orthogonal to the face center line CL. Three RBIs that are 7 mm apart in the heel direction.
A point 5 mm away from the center point Pc on the face center line CL in the 18 direction of the sole portion, and a point 7 mm away from the above point in the toe direction on the lower 5 mm line passing through this point and orthogonal to the face center line CL. Three RBIs that are 7 mm apart in the heel direction.

(2) Launch angle The launch angle obtained in the actual hit test at the above hit point position was measured.
The index of Experimental Example A is set to 100, and the larger the index, the larger the launch angle, indicating that the evaluation is better.

(3) Durability A golf ball is repeatedly hit on the face surface 14A of the hollow golf club head 10 fixed to the shaft with an air cannon, and the number of hits required until the face portion 14 is deformed or damaged is measured and hit. The number of times was indexed. The ball speed was 50 m / s. The hitting point position was the center point Pc of the face surface 14A.
In this case, the measurement result of the hollow golf club head 10 of Experimental Example A is shown as an index set to 100. The larger the index, the better the evaluation.
(4) Total score The total score was the sum of the above-mentioned three indices of initial velocity, launch angle, and durability.
The total score of Experimental Example A is set to 300, and the larger the total score, the better the evaluation.

The hollow golf club head 10 of the experimental example will be described below.
The hollow golf club head 10 used in the experimental examples is a fairway wood, and the following conditions are common except for the parameters specified in the experimental examples.
Material of head body 12: Maraging steel (AM355P)
Material of face portion 14: Maraging steel (C300)
Material of crown part 16: Carbon (CFRP)
Loft angle 15 °
Rye angle 57.5 °
Head volume 180cc

(Condition 1)
With respect to Experimental Examples 1 to 4, as shown in FIG. 17, the conditions specified in claims 1, 2 and 3, that is, the first angle θ1 <the second angle θ2, 15 ° ≦ the second angle θ2 ≦ 30 °, 0. ° ≤ 1st angle θ1 <30 ° was changed.
The conditions specified in claims 4 to 16 are fixed conditions and do not satisfy claims 4 to 16.
Further, in all the experimental examples of the conditions 1 to 8, the head volume is set to be constant at 180 cc to satisfy the claim 17, so that the description of the condition of the claim 17 is omitted in the following description.

Experimental example A corresponds to a comparative example, in which the first angle θ1 (15 °)> the second angle θ2 (10 °), and the first angle θ1 <second angle θ2 defined in claim 1 is satisfied. It does not meet the requirements and is outside the scope of the present invention.
In Experimental Example 1, the first angle θ1 (32 °) <second angle θ2 (34 °), which satisfies claim 1, but does not satisfy claims 2 and 3, and is within the scope of the present invention. be.
In Experimental Example 2, the first angle θ1 (-2 °) <the second angle θ2 (25 °), which satisfies claims 1 and 2, but does not satisfy claim 3, and is within the scope of the present invention. be.
The first angle θ1 is -2 °, which is a negative value, but this is when the extension line α of the front wall outer surface 34A is displaced in the direction closer to the face portion 14 as it goes upward. Equivalent to.
In Experimental Example 3, the first angle θ1 (10 °) <second angle θ2 (12 °), which satisfies claims 1 and 3, but does not satisfy claim 2, and is within the scope of the present invention. be.
In Experimental Example 4, the first angle θ1 (15 °) <the second angle θ2 (30 °), which satisfies claims 1, 2 and 3, and is within the scope of the present invention.

Therefore, as shown in FIG. 17, Experimental Examples 1 to 4 satisfying all the provisions of claim 1 exceed Experimental Example A in which the initial velocity, launch angle, durability, and total score are outside the scope of the present invention.
Further, in Experimental Example 4, which is within the scope of the present invention and satisfies both claims 2 and 3, the initial velocity, launch angle, durability, and total score are within the scope of the present invention, but one of claims 2 and 3. The number exceeds that of Experimental Examples 2 and 3 which do not satisfy the above conditions.

(Condition 2)
As shown in FIG. 18, the conditions specified in claims 4 to 8 were changed for Experimental Examples 5 to 14.
That is, claim 4 satisfies the following equations (1) and (2).
0.5L0 ≤ Lt ≤ 1.5L0 (1)
0.5L0 ≤ Lh ≤ 1.5L0 (2)
Further, claim 5 is that the third distance Lh is larger than the first distance L0 and the second distance Lt, or the second distance Lt is larger than the first distance L0 and the third distance Lh.
Further, claim 6 is that the third distance Lh is smaller than the first distance L0 and the second distance Lt, or the second distance Lt is smaller than the first distance L0 and the third distance Lh.
Further, claim 7 is that the first distance L0 is larger than the second distance Lt and the third distance Lh.
Further, claim 8 is that the first distance L0 is smaller than the second distance Lt and the third distance Lh.
The conditions specified in claims 1 to 3 are fixed conditions and satisfy claims 1 to 3, and the conditions specified in claims 9 to 17 are fixed conditions except for the conditions specified in claim 14. , Claims 9 to 13, 15 and 16 are not satisfied.

Experimental Examples 5, 6, 7, and 8 do not satisfy the conditions specified in claim 4, but satisfy the conditions specified in any of claims 5 to 8.
Experimental Examples 9 to 14 satisfy the conditions specified in claim 4, and satisfy the conditions specified in any of claims 5 to 8.

Therefore, as shown in FIG. 18, Experimental Examples 5 to 14 satisfying any of claims 4 or 5 to 8 do not satisfy the provisions of claim 4 (FIG. 17). The initial velocity, launch angle, and durability are almost the same or higher, and the initial velocity, launch angle, and durability are well-balanced, and the total score exceeds that of Experimental Example 4.

(Condition 3)
As shown in FIG. 19, the conditions specified in claim 9 were changed for Experimental Examples 15 to 17.
That is, claim 9 is that the wall thickness t4 of the rear wall portion 36 is larger than the wall thickness t1 of the connection wall portion 38 in the deepest portion 40.
The conditions specified in claims 1 to 4 shall be satisfied as certain conditions, and any of the conditions specified in claims 5 to 8 shall be satisfied, and the conditions specified in claims 10 to 16 shall be satisfied. , A certain condition was set, and claims 10 to 16 were not satisfied.

Experimental Examples 15 and 17 do not satisfy the conditions specified in claim 9, and Experimental Example 16 satisfies the conditions specified in claim 9.

Therefore, as shown in FIG. 19, Experimental Example 16 satisfying the provision of claim 9 has a good balance of initial velocity, launch angle, and durability as compared with Experimental Examples 15 and 17 not satisfying the provision of claim 9. The total score is excellent.

(Condition 4)
As shown in FIG. 20, the conditions specified in claim 10 were changed for Experimental Examples 17 and 18.
The experimental example 17 in FIG. 20 is the same as the experimental example 17 shown in the above-mentioned condition 3 (FIG. 19).
That is, claim 10 is the wall thickness t1 of the connection wall portion 38 in the deepest portion 40 <the maximum wall thickness t2 of the front end sole wall 1802.
The conditions specified in claims 1 to 4 shall be satisfied as certain conditions, and any of the conditions specified in claims 5 to 8 shall be satisfied, and are specified in claims 9, 11 to 16. The conditions were fixed and did not satisfy claims 9, 11 to 16.

Experimental Example 17 does not satisfy the conditions specified in claim 10, and Experimental Example 18 satisfies the conditions specified in claim 10.

Therefore, as shown in FIG. 20, the experimental example 18 satisfying the provision of claim 10 has a particularly high initial velocity as compared with the experimental example 17 not satisfying the provision of claim 10, and the total score is excellent.

(Condition 5)
As shown in FIG. 21, the conditions specified in claim 11 were changed for Experimental Examples 19, 20, and 21.
That is, claim 11 is the wall thickness t1 of the connection wall portion 38 in the deepest portion 40 ≦ the wall thickness t3 of the front wall portion 34 ≦ the maximum wall thickness t2 of the front end sole wall 1802.
The conditions specified in claims 1 to 4 shall be satisfied as certain conditions, and any of the conditions specified in claims 5 to 8 shall be satisfied, and the conditions specified in claims 9 and 10 shall be satisfied. The conditions specified in claims 11 to 16 are defined as constant conditions and do not satisfy the conditions.

Experimental Examples 19 and 20 do not satisfy the conditions specified in claim 11, and Experimental Example 21 satisfies the conditions specified in claim 11.

Therefore, as shown in FIG. 21, Experimental Example 21 satisfying the provision of claim 11 has the same initial velocity, launch angle, durability, and total score as those of Experimental Examples 19 and 20 not satisfying the provision of claim 11. As mentioned above, the total score is excellent.

(Condition 6)
As shown in FIG. 22, the conditions specified in claims 12 and 13 were changed for Experimental Examples 22 to 27.
That is, claim 12 is a wall thickness t1 ≦ 1.5 mm of the connection wall portion 38 in 1.0 mm ≦ the deepest part 40.
Further, claim 13 is a maximum wall thickness t2 ≦ 2.5 mm of 1.2 mm ≦ front end sole wall 1802.
The conditions specified in claims 1 to 4 shall be satisfied as certain conditions, and any of the conditions specified in claims 5 to 8 shall be satisfied, and the conditions specified in claims 9 and 10 shall be satisfied. The conditions specified in claims 14 to 16 are fixed and do not satisfy the conditions.
Further, the conditions specified in claim 11 do not satisfy the conditions in Experimental Examples 22, 23, and 26, and satisfy the conditions in Experimental Examples 24, 25, and 27.

Experimental Examples 22 and 24 satisfy the conditions specified in claim 12 and do not satisfy the conditions specified in claim 13.
Experimental Examples 23 and 25 do not satisfy the conditions specified in claim 12, but satisfy the conditions specified in claim 13.
Experimental Examples 26 and 27 satisfy the conditions specified in claims 12 and 13.

Therefore, as shown in FIG. 22, Experimental Examples 26 and 27 satisfying the conditions specified in claims 12 and 13 do not satisfy the provisions of either claim 12 or claims 22 to 25. Compared to, the initial velocity, launch angle, and durability are almost the same or better, and the balance is good, and the total score is excellent.

(Condition 7)
As shown in FIG. 23, the conditions specified in claims 14, 15 and 16 were changed for Experimental Examples 28 to 36.
That is, claim 14 is the deepest distance Lx ≦ 20 mm of the deepest portion 40 of the 3 mm ≦ groove 32.
Since the deepest distance Lx almost coincides with the maximum distance among the three distances of the first distance L0, the second distance Lt, and the third distance Lh, Experimental Example 28 to Condition 7 shown in FIG. 23 In 36, the deepest distance Lx is, for convenience, the maximum distance among the three distances of the first distance L0, the second distance Lt, and the third distance Lh.
Further, claim 15 is 40 mm ≦ groove length W ≦ 80 mm.
Further, claim 16 is the shortest distance Lf ≦ 10 mm or less connecting 4 mm ≦ the deepest portion 40 and the face inner surface 14B.
The conditions specified in claims 1 to 4 shall be satisfied as certain conditions, and any of the conditions specified in claims 5 to 8 shall be satisfied, and the conditions specified in claims 9 to 12 shall be satisfied. , It was assumed that certain conditions were met.

Experimental Example 28 satisfies the conditions specified in claims 14 and does not satisfy the conditions specified in claims 15 and 16.
Experimental example 29 satisfies the conditions specified in claim 15 and does not satisfy the conditions specified in claims 14 and 16.
Experimental example 30 satisfies the conditions specified in claims 16 and does not satisfy the conditions specified in claims 14 and 15.
Experimental example 31 satisfies the conditions specified in claims 14 and 15, and does not satisfy the conditions specified in claim 16.
Experimental example 32 satisfies the conditions specified in claims 14 and 15, and does not satisfy the conditions specified in claim 16.
Experimental example 33 satisfies the conditions specified in claims 15 and 16, and does not satisfy the conditions specified in claim 14.
Experimental Example 34 satisfies the conditions specified in claims 15 and 16, and does not satisfy the conditions specified in claim 14.
Experimental example 35 satisfies the conditions specified in claims 14 and 16, and does not satisfy the conditions specified in claim 15.
Experimental example 36 satisfies the conditions specified in claims 14 and 16, and does not satisfy the conditions specified in claim 15.

Therefore, as shown in FIG. 23, the experimental examples 31 to 36 satisfying the conditions of the two claims among the claims 14, 15 and 16 are the conditions of one of the claims 14, 15 and 16. The initial velocity, launch angle, and durability are almost the same or higher as compared with Experimental Examples 28 to 30 which do not satisfy the conditions of the remaining two claims, and the total score is excellent.

(Condition 8)
As shown in FIG. 24, for Experimental Examples 37, 38, and 39, the conditions specified in claims 1 to 16 were set to suitable values within those conditions.
That is, the conditions specified in claims 1 to 4 are satisfied, and any of the conditions specified in claims 5 to 8 is satisfied, and the conditions specified in claims 9 to 16 are satisfied.
Therefore, as shown in FIG. 24, Experimental Examples 37, 38, and 39 have substantially the same or higher initial velocity, launch angle, and durability than the other Experimental Examples 1 to 36, and are excellent in total points.

10 Hollow golf club head 12 Head body 14 Face body 14A Face surface 14B Face inner surface 16 Crown part 16A Crown surface 16B Crown inner surface 18 Sole part 18A Sole surface 18B Sole inner surface 1802 Front end sole wall 19 Leading edge 20 Side part 22 Toe 24 Heel 26 Face back 28 Hollow part HP Horizontal plane Pc Face center point CL Face center line X Plane Pfc Face center reference cross section Pf Face reference cross section 32 Groove 34 Front wall 34A Front wall outer surface 36 Rear wall 36A Rear wall outer surface 38 Connection wall 38A Connection wall outer surface 39 Weight part 40 Deepest part 40A 1st deepest part 40B 2nd deepest part 40C 3rd deepest part Pr1 1st plane Pr2 2nd plane Pr3 3rd plane Pr4 4th plane Lr1 1st reference line α Front wall outer surface Extension line β Extension line of the outer surface of the rear wall γ Intersection point L0 First distance (face center reference plane)
Lt 2nd distance (toe side)
Lh 3rd distance (heel side)
Lx Deepest distance t1 Wall thickness at the deepest part t2 Maximum wall thickness at the front end sole wall t3 Wall thickness at the front wall t4 Wall thickness at the rear wall W Groove length Lf Shortest connecting the deepest part and the inner surface of the face distance

Claims (17)

A head body including a face portion having a vertical height and extending to the left and right and a sole portion extending rearward from the lower portion of the face portion is provided, and the inside of the head body is a hollow portion. A hollow golf club head in which a groove portion extending in the toe heel direction is formed while being recessed upward in a portion of the sole portion near the face portion.
The groove portion protrudes upward from the portion of the sole portion closer to the face portion and protrudes upward from the portion of the sole portion closer to the face back than the front wall portion and faces the front wall portion. A rear wall portion and a connecting wall portion connecting the upper end of the front wall portion and the upper end of the rear wall portion are provided.
In a reference state in which the hollow golf club head is installed according to a predetermined lie angle and loft angle with respect to the horizontal plane, the head body is mounted on a plane including a normal passing through the center point of the face surface and orthogonal to the horizontal plane. The broken cross section is used as the face center reference cross section.
A first plane parallel to the face center reference cross section and 10 mm away from the face center reference cross section to the toe side, and a place parallel to the face center reference cross section and 10 mm away from the face center reference cross section to the heel side. The area of the head body sandwiched between the second plane and the second plane located in is defined as the first area.
Arbitrary cross section parallel to the face center reference cross section in the first region, located on the face portion side of the rear wall portion and an extension line of the front wall outer surface which is a surface located on the face back side of the front wall portion. The first reference line is a straight line that passes through the intersection with the extension line of the outer surface of the rear wall, which is the surface to be crossed, and is orthogonal to the horizontal plane.
The angle formed by the extension line of the outer surface of the front wall and the first reference line in the arbitrary cross section is defined as the first angle θ1.
When the angle formed by the extension line of the outer surface of the rear wall and the first reference line in the arbitrary cross section is the second angle θ2.
The second angle θ2 is larger than the first angle θ1.
A hollow golf club head that features that. The rear wall portion is displaced toward the face portion as it goes upward, and the rear wall portion is displaced toward the face portion.
The second angle θ2 is 15 ° or more and 30 ° or less.
The hollow golf club head according to claim 1. The front wall portion extends upward on the first reference line or is displaced toward the face back as it reaches upward.
The first angle θ1 is 0 ° or more and less than 30 °.
The hollow golf club head according to claim 1 or 2. In any cross section parallel to the face center reference cross section, a portion where the outer surface of the connecting wall, which is a downwardly facing surface of the connecting wall portion, is separated most upward from the horizontal plane is defined as the deepest portion of the groove portion.
The deepest portion in the face center reference cross section is defined as the first deepest portion, and the height of the first deepest portion from the horizontal plane is defined as the first distance L0.
A cross section broken in the third plane, with the deepest part of the cross section broken in the third plane located parallel to the face center reference cross section and 20 mm away from the face center reference cross section on the toe side as the second deepest part. The height of the second deepest portion from the plane passing through the lowermost end of the sole surface and parallel to the horizontal plane is defined as the second distance Lt.
A cross section broken in the fourth plane, with the deepest part of the cross section broken in the fourth plane located parallel to the face center reference cross section and 20 mm away from the face center reference cross section on the heel side as the third deepest part. When the height of the third deepest portion from the plane passing through the lowermost end of the sole surface and parallel to the horizontal plane is the third distance Lh.
The following equations (1) and (2) are satisfied.
The hollow golf club head according to any one of claims 1 to 3.
0.5L0 ≤ Lt ≤ 1.5L0 (1)
0.5L0 ≤ Lh ≤ 1.5L0 (2) In any cross section parallel to the face center reference cross section, a portion where the outer surface of the connecting wall, which is a downwardly facing surface of the connecting wall portion, is separated most upward from the horizontal plane is defined as the deepest portion of the groove portion.
The deepest portion in the face center reference cross section is defined as the first deepest portion, and the height of the first deepest portion from the horizontal plane is defined as the first distance L0.
A cross section broken in the third plane, with the deepest part of the cross section broken in the third plane located parallel to the face center reference cross section and 20 mm away from the face center reference cross section on the toe side as the second deepest part. The height of the second deepest portion from the plane passing through the lowermost end of the sole surface and parallel to the horizontal plane is defined as the second distance Lt.
A cross section broken in the fourth plane, with the deepest part of the cross section broken in the fourth plane located parallel to the face center reference cross section and 20 mm away from the face center reference cross section on the heel side as the third deepest part. When the height of the third deepest portion from the plane passing through the lowermost end of the sole surface and parallel to the horizontal plane is the third distance Lh.
The third distance Lh is larger than the first distance L0 and the second distance Lt, or the second distance Lt is larger than the first distance L0 and the third distance Lh.
The hollow golf club head according to any one of claims 1 to 4. In any cross section parallel to the face center reference cross section, a portion where the outer surface of the connecting wall, which is a downwardly facing surface of the connecting wall portion, is separated most upward from the horizontal plane is defined as the deepest portion of the groove portion.
The deepest portion in the face center reference cross section is defined as the first deepest portion, and the height of the first deepest portion from the horizontal plane is defined as the first distance L0.
A cross section broken in the third plane, with the deepest part of the cross section broken in the third plane located parallel to the face center reference cross section and 20 mm away from the face center reference cross section on the toe side as the second deepest part. The height of the second deepest portion from the plane passing through the lowermost end of the sole surface and parallel to the horizontal plane is defined as the second distance Lt.
A cross section broken in the fourth plane, with the deepest part of the cross section broken in the fourth plane located parallel to the face center reference cross section and 20 mm away from the face center reference cross section on the heel side as the third deepest part. When the height of the third deepest portion from the plane passing through the lowermost end of the sole surface and parallel to the horizontal plane is the third distance Lh.
The third distance Lh is smaller than the first distance L0 and the second distance Lt, or the second distance Lt is smaller than the first distance L0 and the third distance Lh.
The hollow golf club head according to any one of claims 1 to 4. In any cross section parallel to the face center reference cross section, a portion where the outer surface of the connecting wall, which is a downwardly facing surface of the connecting wall portion, is separated most upward from the horizontal plane is defined as the deepest portion of the groove portion.
The deepest portion in the face center reference cross section is defined as the first deepest portion, and the height of the first deepest portion from the horizontal plane is defined as the first distance L0.
A cross section broken in the third plane, with the deepest part of the cross section broken in the third plane located parallel to the face center reference cross section and 20 mm away from the face center reference cross section on the toe side as the second deepest part. The height of the second deepest portion from the plane passing through the lowermost end of the sole surface and parallel to the horizontal plane is defined as the second distance Lt.
A cross section broken in the fourth plane, with the deepest part of the cross section broken in the fourth plane located parallel to the face center reference cross section and 20 mm away from the face center reference cross section on the heel side as the third deepest part. When the height of the third deepest portion from the plane passing through the lowermost end of the sole surface and parallel to the horizontal plane is the third distance Lh.
The first distance L0 is larger than the second distance Lt and the third distance Lh.
The hollow golf club head according to any one of claims 1 to 4. In any cross section parallel to the face center reference cross section, a portion where the outer surface of the connecting wall, which is a downwardly facing surface of the connecting wall portion, is separated most upward from the horizontal plane is defined as the deepest portion of the groove portion.
The deepest portion in the face center reference cross section is defined as the first deepest portion, and the height of the first deepest portion from the horizontal plane is defined as the first distance L0.
A cross section broken in the third plane, with the deepest part of the cross section broken in the third plane located parallel to the face center reference cross section and 20 mm away from the face center reference cross section on the toe side as the second deepest part. The height of the second deepest portion from the plane passing through the lowermost end of the sole surface and parallel to the horizontal plane is defined as the second distance Lt.
A cross section broken in the fourth plane, with the deepest part of the cross section broken in the fourth plane located parallel to the face center reference cross section and 20 mm away from the face center reference cross section on the heel side as the third deepest part. When the height of the third deepest portion from the plane passing through the lowermost end of the sole surface and parallel to the horizontal plane is the third distance Lh.
The first distance L0 is smaller than the second distance Lt and the third distance Lh.
The hollow golf club head according to any one of claims 1 to 4. In any cross section parallel to the face center reference cross section, when the portion where the outer surface of the connecting wall is most upwardly separated from the horizontal plane is defined as the deepest portion of the groove portion.
The wall thickness t4 of the rear wall portion is larger than the wall thickness t1 of the connection wall portion in the deepest portion.
The hollow golf club head according to any one of claims 1 to 8. The sole portion has a front end sole wall connecting the lower end of the front wall portion and the leading edge.
In any cross section parallel to the face center reference cross section, when the portion where the outer surface of the connecting wall is most upwardly separated from the horizontal plane is defined as the deepest portion of the groove portion.
The maximum wall thickness t2 of the front end sole wall is larger than the wall thickness t1 of the connection wall portion in the deepest portion.
The hollow golf club head according to any one of claims 1 to 9. The sole portion has a front end sole wall connecting the lower end of the front wall portion and the leading edge.
In any cross section parallel to the face center reference cross section, when the portion where the outer surface of the connecting wall is most upwardly separated from the horizontal plane is defined as the deepest portion of the groove portion.
The wall thickness t3 of the front wall portion is not less than or equal to the wall thickness t1 of the connection wall portion in the deepest portion and is equal to or less than the maximum wall thickness t2 of the front end sole wall.
The hollow golf club head according to any one of claims 1 to 9. The wall thickness t1 of the connection wall portion in the deepest portion is 1.0 mm or more and 1.5 mm or less.
The hollow golf club head according to claim 10 or 11. In any cross section parallel to the face center reference cross section, the maximum wall thickness t2 of the front end sole wall is 1.2 mm or more and 2.5 mm or less.
The hollow golf club head according to any one of claims 10 to 12. In any cross section parallel to the face center reference cross section, the portion where the outer surface of the connecting wall is separated most upward from the horizontal plane is defined as the deepest portion of the groove portion.
When the height of the deepest part from the horizontal plane is taken as the deepest part distance Lx,
The deepest distance Lx is 3 mm or more and 20 mm or less.
The hollow golf club head according to any one of claims 1 to 13. The groove length W along the toe heel direction of the groove portion is 40 mm or more and 80 mm or less.
The hollow golf club head according to any one of claims 1 to 14. The surface of the face portion facing the hollow portion is defined as the inner surface of the face.
In any cross section parallel to the face center reference cross section, when the portion where the outer surface of the connecting wall is most upwardly separated from the horizontal plane is defined as the deepest portion of the groove portion.
In the arbitrary cross section, the shortest distance Lf connecting the deepest portion and the inner surface of the face is 4 mm or more and 10 mm or less.
The hollow golf club head according to any one of claims 1 to 15. The volume of the head body is 100 cc or more and 200 cc or less.
The hollow golf club head according to any one of claims 1 to 16.

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