Golf club head

Abstract

A golf club head includes a hollow interior and a face portion. The golf club head includes a body member that includes an opening, and a face member that includes the face portion, that covers the opening, and that is welded to the body member. The face member includes a rearward extending portion that extends from an outer edge of the face portion toward a back side. The rearward extending portion includes a sole-side rearward extending portion disposed in a sole-side portion of the face member, a toe-side rearward extending portion disposed in a toe-side portion of the face member, and a heel-side rearward extending portion disposed in a heel-side portion of the face member. The face member also includes a crown-side edge portion formed by an absence of the rearward extending portion in a crown-side portion of the face member.

Description

CROSS REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to Japanese Patent Application No. 2025-6467 filed on Jan. 16, 2025. The entire contents of this Japanese Patent Application are hereby incorporated by reference.BACKGROUNDTechnical Field

[0002] The present disclosure relates to golf club heads.Description of the Related Art

[0003] A golf club head including a cup face as a face member has been known. JP 2016-26557A (US 2015 / 0375068 A1) discloses a golf club head including: a cup face that includes a rising portion extending from a peripheral edge of a face portion toward the rear surface side of the face portion; and a head body. The cup face can be produced using a different material and a different manufacturing method from those used for the head body.SUMMARY

[0004] The inventor of the present disclosure has determined that conventional cup faces have room for improvement. One of the objectives of the present disclosure is to provide a golf club head that exhibits enhanced performance achieved by including a face member having a new structure.

[0005] In one aspect, a golf club head includes a face portion that includes a striking face as a front surface, a crown portion, and a sole portion. The golf club head includes a hollow interior. The golf club head includes a body member that includes an opening, and a face member that includes the face portion, that covers the opening, and that is welded to the body member. The face member includes a rearward extending portion that extends from an outer edge of the face portion toward a back side. The rearward extending portion includes a sole-side rearward extending portion disposed in a sole-side portion of the face member, a toe-side rearward extending portion disposed in a toe-side portion of the face member, and a heel-side rearward extending portion disposed in a heel-side portion of the face member. The face member also includes a crown-side edge portion formed by an absence of the rearward extending portion in a crown-side portion of the face member.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1A and FIG. 1B are front views of a golf club head according to an embodiment;

[0007] FIG. 2 is a perspective view of a body member that is a constituent member of the golf club head;

[0008] FIG. 3 is a perspective view of a face member that is a constituent member of the golf club head;

[0009] FIG. 4 is a cross-sectional view taken along line A-A in FIG. 1A;

[0010] FIG. 5 is a cross-sectional view taken along line B-B in FIG. 1A;

[0011] FIG. 6 is a cross-sectional view taken along line C-C in FIG. 1A;

[0012] FIG. 7 is a cross-sectional view taken along line D-D in FIG. 1A;

[0013] FIG. 8 is an enlarged view of the front view in FIG. 1A;

[0014] FIG. 9 is an enlarged view of the cross-sectional view in FIG. 4;

[0015] FIG. 10 is a partially enlarged view of FIG. 4;

[0016] FIG. 11 is a partially enlarged view of FIG. 5;

[0017] FIG. 12 is a partially enlarged view of FIG. 10; and

[0018] FIG. 13 is a conceptual diagram for illustrating a reference state.DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the present disclosure will be described in detail based on preferred embodiments with appropriate references to the accompanying drawings.

[0020] In the present disclosure, a reference state, a reference perpendicular plane, a toe-heel direction, a face-back direction, an up-down direction, a face center, a radial cross section, an upright cross section, a horizontal cross section, a vertical cross section, and a vertical cross-sectional contour line are defined.

[0021] The reference state is defined as a state where a head is placed at a predetermined lie angle on a ground plane HP. As shown in FIG. 13, in the reference state, a shaft axis line Z lies on (is contained in) a plane VP that is perpendicular to the ground plane HP. The shaft axis line Z is defined as the center line of a shaft. Typically, the shaft axis line Z coincides with the center line of a hosel hole. The plane VP is referred to as the reference perpendicular plane. The predetermined lie angle is shown in product catalogs, for example.

[0022] In the reference state, a face angle is 0°. That is, in a planer view of the head as viewed from above, a tangent line to the head at its face center on the striking face is set to be parallel to the toe-heel direction. The definitions of the face center and the toe-heel direction are explained below.

[0023] The toe-heel direction is defined as the direction of an intersection line NL between the reference perpendicular plane VP and the ground plane HP (see FIG. 13).

[0024] The face-back direction is defined as a direction that is perpendicular to the toe-heel direction and is parallel to the ground plane HP. The face side in the face-back direction is also referred to as “front side”. The back side in the face-back direction is also referred to as “rear side”.

[0025] The up-down direction is defined as a direction that is perpendicular to the toe-heel direction and perpendicular to the face-back direction. In other words, the up-down direction is a direction perpendicular to the ground plane HP. As used herein, “upper” in the up-down direction is also referred to as “above”, and “lower” in the up-down direction is also referred to as “below”. Additionally, as used herein, “ascend” refers to extending or going upward (toward the upper side), and “descend” refers to extending or going downward (toward the lower side).

[0026] The face center is determined in the following manner. First, a point Pr is selected roughly at the center of a striking face in the up-down direction and the toe-heel direction. Next, a flat plane that passes through the point Pr, extends in the direction of a line normal to the striking face at the point Pr, and is parallel to the toe-heel direction is determined. An intersection line between this flat plane and the striking face is drawn, and a midpoint Px of this intersection line is determined. Next, a flat plane that passes through the midpoint Px, extends in the direction of a line normal to the striking face at the midpoint Px, and is parallel to the up-down direction is determined. An intersection line between this flat plane and the striking face is drawn, and a midpoint Py of this intersection line is determined. Next, a flat plane that passes through the midpoint Py, extends in the direction of a line normal to the striking face at the midpoint Py, and is parallel to the toe-heel direction is determined. An intersection line between this flat plane and the striking face is drawn, and a midpoint Px of this intersection line is newly determined. Next, a flat plane that passes through this newly-determined midpoint Px, extends in the direction of a line normal to the striking face at this midpoint Px, and is parallel to the up-down direction is determined. An intersection line between this flat plane and the striking face is drawn, and a midpoint Py of this intersection line is newly determined. By repeating the above-described steps, points Px and Py are sequentially determined. In the course of repeating these steps, when the distance between a newly-determined midpoint Py and a midpoint Py determined in the immediately preceding step first becomes less than or equal to 0.5 mm, the newly-determined midpoint Py (the midpoint Py determined last) is defined as the face center.

[0027] Note that, for some heads, the face center may be difficult to determine based on the foregoing definition. As used throughout the present disclosure, the term “face center” may be replaced with the term “sweet spot”. The “sweet spot” is defined as an intersection point between the striking face and a straight line that passes through the center of gravity of the head and is perpendicular to the striking face.

[0028] The radial cross section is defined as each of cross sections taken along flat planes that contain a straight line normal to the striking face at the face center. A large number of such flat planes can be defined, and a large number of radial cross sections can be obtained accordingly.

[0029] Among the radial cross sections, a radial cross section that is perpendicular to the ground plane HP is referred to as the upright cross section. Among the radial cross sections, a radial cross section that is perpendicular to the upright cross section is referred to as the horizontal cross section.

[0030] A vertical cross section is defined as each of cross sections that are perpendicular to the ground plane HP and parallel to the face-back direction. Vertical cross sections are obtained at respective positions along the toe-heel direction. A vertical cross-sectional contour line refers to the contour line of the head outer surface in a vertical cross section.

[0031] FIG. 1A and FIG. 1B are front views of a golf club head 100 according to one embodiment. FIG. 2 is a perspective view of a body member b1 of the head 100. FIG. 3 is a perspective view of a face member f1 of the head 100. FIG. 3 is a perspective view of the face member f1 as viewed from the rear side of a face portion 104. FIG. 4 is a cross-sectional view taken along line A-A in FIG. 1A. FIG. 5 is a cross-sectional view taken along line B-B in FIG. 1A. FIG. 6 is a cross-sectional view taken along line C-C in FIG. 1A. FIG. 7 is a cross-sectional view taken along line D-D in FIG. 1A.

[0032] Referring to FIG. 1A, FIG. 4 (cross section taken along line A-A) shows a cross section taken along a flat plane PL1 that contains a normal line N1 that is a straight line normal to a striking face 104a at a face center C1. FIG. 5 (cross section taken along line B-B) shows a cross section taken along a flat plane PL2 that contains the normal line N1. FIG. 6 (cross section taken along line C-C) shows a cross section taken along a flat plane PL3 that contains the normal line N1. FIG. 7 (cross section taken along line D-D) shows a cross section taken along a flat plane PL4 that contains the normal line N1. FIG. 4, FIG. 5, FIG. 6, and FIG. 7 are the radial cross sections as defined above. Among the radial cross sections, FIG. 4 shows the upright cross section as defined above, and FIG. 5 shows the horizontal cross section as defined above.

[0033] The head 100 includes the face portion 104, a crown portion 106, a sole portion 108, and a hosel portion 110. The face portion 104 includes the striking face 104a and a face inner surface 104b. The striking face 104a is the outer surface (front surface) of the face portion 104. The face inner surface 104b is the inner surface (rear surface) of the face portion 104. The crown portion 106 includes a crown outer surface 106a and a crown inner surface 106b. The sole portion 108 includes a sole outer surface 108a and a sole inner surface 108b.

[0034] As shown in FIG. 1B, the striking face 104a includes an outer edge k1. The outer edge k1 is the contour line of the striking face 104a. The outer edge k1 is the boundary between the striking face 104a and its adjacent portions. The outer edge k1 of the striking face 104a can be defined as follows. In each of the radial cross sections, when a curvature radius of the cross-sectional contour line of the head outer surface is sequentially observed from the face center C1 toward the outside of the striking face 104a, a point at which the curvature radius becomes 200 mm for the first time is determined. A set of these points can be defined as the outer edge k1 of the striking face 104a.

[0035] The hosel portion 110 includes a protruding portion 110a that is exposed to the outside of the head 100 and protrudes from the crown outer surface 106a, and an internal extending portion 110b that is positioned inside the head 100. The hosel portion 110 also includes a hosel hole 112. The hosel hole 112 has an opening at the upper end of the protruding portion 110a and extends continuously from the protruding portion 110a to the internal extending portion 110b. The head 100 may also include a skirt portion (side portion) that extends between the crown portion 106 and the sole portion 108. Note that the “striking face” is also simply referred to as a “face”.

[0036] As shown in FIG. 4 to FIG. 7, the head 100 includes a hollow interior h1. The head 100 is a hollow head. The head 100 is a wood type head. The head 100 is a fairway wood type head. Alternatively, the head 100 may be a hybrid type head. Further alternatively, the head 100 may be a driver head. From the viewpoint of an advantageous effect of improving rebound performance when striking a ball placed directly on the ground (as described later), the head 100 is preferably a fairway wood type head or a hybrid type head, and more preferably a fairway wood type head.

[0037] From the viewpoint of constituent members, the head 100 includes the face member f1 and the body member b1. The face member f1 is welded to the body member b1. As shown in FIG. 2, the body member b1 includes an opening 114 formed in its front portion. The opening 114 is covered by the face member f1. The body member b1 includes the entirety of the hosel portion 110. The body member b1 includes the entirety of the crown portion 106. The body member b1 includes a part of the sole portion 108 (excluding its front portion). The front portion of the sole portion 108 is included in the face member f1.

[0038] As shown in FIG. 2, the body member b1 includes a joint surface 116. The joint surface 116 is a front end surface of the body member b1. The body member b1 is joined to the face member f1 at the joint surface 116.

[0039] As shown in FIG. 3, the face member f1 includes a joint surface 118. The joint surface 118 is a rear end surface of a rearward extending portion E1 (described later). The joint surface 118 is joined to the joint surface 116 of the body member b1.

[0040] A boundary k2 between the body member b1 and the face member f1 is formed on the outer surface of the head 100 (see FIG. 1A and FIG. 1B). The outer surface of the head 100 is polished after the body member b1 and the face member f1 are welded together, whereby the outer surface of the head 100 becomes flush at the boundary k2 to form a smoothly continuous curved surface. The boundary k2 is not viewable in the finished head 100.

[0041] The face member f1 is a cup-shaped member as a whole that includes a bottom portion forming the face portion 104. The face member f1 includes the entirety of the face portion 104. The face member f1 includes the entirety of the striking face 104a. The face member f1 includes the face portion 104 and the rearward extending portion E1 that extends from the outer edge of the face portion 104 toward the back side. However, the face member f1 does not include a rearward extending portion E1 located in its crown-side portion. Accordingly, the face member f1 is different from a conventional cup face. As shown in FIG. 3, the rearward extending portion E1 includes a sole-side rearward extending portion Es disposed in a sole-side portion of the face member f1, a toe-side rearward extending portion Et disposed in a toe-side portion of the face member f1, and a heel-side rearward extending portion Eh disposed in a heel-side portion of the face member f1.

[0042] As shown in FIG. 1B, the outer edge k1 of the striking face 104a includes a point Qt, located on the upper toe side, at which the curvature radius reaches a local minimum. When the local minimum curvature radius occurs not only at a specific point but continues in a portion having a length, the point Qt is defined as the midpoint of the path length of that portion, the path length being measured following (along) the outer edge k1. When there is a point forming a corner and having a curvature radius of zero, an apex of the corner is defined as the point Qt. Among the radial cross sections, a flat plane PL5 passing through the point Qt is determined. Note that when the outer edge k1 is interrupted on the upper toe side, the midpoint of a shortest line connecting the interrupted ends of the outer edge k1 can be defined as the point Qt.

[0043] Similarly, the outer edge k1 of the striking face 104a includes a point Qh, located the upper heel side, at which the curvature radius reaches a local minimum. When the local minimum curvature radius occurs not only at a specific point but continues in a portion having a length, the point Qh is defined as the midpoint of the path length of that portion, the path length being measured following (along) the outer edge k1. When there is a point forming a corner and having a curvature radius of zero, an apex of the corner is defined as the point Qh. Among the radial cross sections, a flat plane PL6 passing through the point Qh is determined. Note that when the outer edge k1 is interrupted on the upper heel side, the midpoint of a shortest line connecting the interrupted ends of the outer edge k1 can be defined as the point Qh.

[0044] A region that is located above both the flat plane PL5 and the flat plane PL6 can be defined as a crown region CR. A region that is located below both the flat plane PL5 and the flat plane PL6 can be defined as a sole region SL. A region that is located above the flat plane PL5 and below the flat plane PL6 can be defined as a heel region HL. A region that is located below the flat plane PL5 and above the flat plane PL6 can be defined as a toe region TE.

[0045] A part of the rearward extending portion E1 that is located in the sole region SL can be defined as the sole-side rearward extending portion Es. A part of the rearward extending portion E1 that is located in the heel region HL can be defined as the heel-side rearward extending portion Eh. A part of the rearward extending portion E1 that is located in the toe region TE can be defined as the toe-side rearward extending portion Et.

[0046] As shown in FIG. 1B, a toe-heel directional zone U1 (a zone delimited only in the toe-heel direction) that extends from the point Qt to the point Qh is defined. In the head 100, a portion located on the heel side relative to the point Qt and on the toe side relative to the point Qh is the zone U1. Within the zone U1, the rearward extending portion E1 is absent from the crown region CR. That is, the rearward extending portion E1 is not present in the crown region CR within the zone U1 located on the heel side relative to the point Qt and on the toe side relative to the point Qh. On the toe side relative to the point Qt, the rearward extending portion E1 may be present in the crown region CR. On the heel side relative to the point Qh, the rearward extending portion E1 may be present in the crown region CR.

[0047] The face member f1 includes a crown-side edge portion G1, in its crown-side portion, formed by the absence of the rearward extending portion E1 (see FIG. 3). The crown-side edge portion G1 is disposed in the toe-heel directional zone U1. The crown-side edge portion G1 is positioned on and / or in the vicinity of the boundary between the crown portion 106 and the face portion 104.

[0048] As shown in FIG. 3, the face member f1 includes a beveled portion 119 on the upper heel side. The beveled portion 119 is disposed at a position adjoining the hosel portion 110. The rearward extending portion E1 is not present at the position where the beveled portion 119 is located. When the rearward extending portion E1 of the face member f1 is welded to the body member b1, the beveled portion 119 forms a gap between the face member f1 and the body member b1. By looking into the inner surface of the head 100 through this gap, the weld state between the rearward extending portion E1 and the body member b1 can be observed. The gap formed by the beveled portion 119 is then filled with a weld bead.

[0049] The face member f1 is made of a metal. Examples of the metal include stainless steel, maraging steel, a titanium alloy, an aluminum alloy, and a magnesium alloy. A part of the face member f1 may be made of a non-metal material. For example, a part of the face member f1 may be made of a carbon fiber reinforced resin. However, at least a portion to be welded to the body member b1 (the joint surface 118 and the crown-side edge portion G1 described later) is made of a material that is weldable to the body member b1. From the viewpoint of strength, examples of the preferable material for the face member f1 include a titanium alloy and maraging steel. There is no limitation on the method for producing the face member f1. From the viewpoint of strength, the face member f1 may be produced by pressing a plate material. A rolled material may be used as the plate material. Rolled materials have few defects and high strength. In addition, rolled materials are formed with high thickness accuracy. The use of a rolled material improves the accuracy of the wall thickness of the face portion 104. The face member f1 may be produced by forging, for example. Alternatively, the face member f1 may be produced by casting. As will be described later, the face member f1 of the present embodiment does not include the rearward extending portion E1 on the crown side.

[0050] Accordingly, the face member f1 can be formed more easily by pressing or forging compared to a conventional cup face. In the present embodiment, the face member f1 is produced by pressing a rolled material. More specifically, the producing process of the face member f1 may include: a first step of machining a plate material (rolled material) to adjust wall thickness by CNC processing; a second step of pressing the plate material after being subjected to the first step; and a third step of adjusting the shape of the rearward extending portion E1 of the material after being subjected to the second step by CNC processing. In the second step, the face portion is shaped to include curved surface (bulge and roll) and the rearward extending portion E1. The third step of adjusting the shape of the rearward extending portion E1 may be performed after the pressing step (second step). The third step includes adjusting the length of the rearward extending portion E1 and / or adjusting the shape of the outer surface of the rearward extending portion E1. Laser cutting may be used to adjust the length of the rearward extending portion E1. CNC processing may be used to adjust the shape of the outer surface of the rearward extending portion E1. When the shape of the outer surface of the rearward extending portion E1 is adjusted in the third step, the wall thickness of the rearward extending portion E1 in the first step can be set in consideration of the amount of material to be removed from the rearward extending portion E1 in the third step. Note that “CNC” is an abbreviation for Computerized Numerical Control.

[0051] The body member b1 is made of a metal. Examples of the metal include stainless steel, maraging steel, a titanium alloy, an aluminum alloy, and a magnesium alloy. A part of the body member b1 may be made of a non-metal material. For example, a part of the body member b1 may be made of a carbon fiber reinforced resin. The face member f1 is welded to the body member b1, and the joint surface 116 of the body member b1 is formed of a metal. The body member b1 may be integrally formed as a single-piece member. The body member b1 may be formed by joining a plurality of members to each other. For example, the body member b1 may be formed by joining a member made of a metal to a member made of a carbon fiber reinforced plastic. In the present embodiment, the entirety of the body member b1 is formed of a metal. There is no limitation on the method for producing the body member b1. In the present embodiment, the body member b1 is produced by casting (lost-wax precision casting).

[0052] The head 100 includes an internal weight portion 120. The body member b1 includes the internal weight portion 120. The internal weight portion 120 is disposed on the inner side of the sole portion 108. The internal weight portion 120 is located on the sole inner surface 108b of the sole portion 108. The internal weight portion 120 is a portion that protrudes from the sole inner surface 108b.

[0053] The internal weight portion 120 is integrated with the sole portion 108. The internal weight portion 120 is formed integrally with the sole portion 108. The internal weight portion 120 is integrated with the body member b1. The body member b1 including the internal weight portion 120 is integrally formed as a single-piece member. The method for forming the body member b1 is casting. The body member b1 is formed by lost-wax precision casting. The internal weight portion 120 may be a separate member from the sole portion 108. The internal weight portion 120 may be formed separately from the body member b1. The internal weight portion 120 may be formed independently and fixed to the sole portion 108. Examples of this fixing method include welding, press fitting, screwing, and bonding.

[0054] The internal weight portion 120 is positioned on the back side relative to the face portion 104. The internal weight portion 120 is spaced apart from the face portion 104. The internal weight portion 120 is positioned on the back side relative to a flat plane PL (described later).

[0055] The internal weight portion 120 (a central portion 120M described later) includes a base portion 122 and a protruding portion 124 that protrudes from the base portion 122 toward the face side. The base portion 122 protrudes upward from the sole inner surface 108b of the sole portion 108. The base portion 122 is integrated with the sole portion 108. The protruding portion 124 extends upward as it goes toward the face side.

[0056] The protruding portion 124 is positioned on the face side relative to the head center of gravity. The entirety of the protruding portion 124 is positioned on the face side relative to the head center of gravity.

[0057] As shown in FIG. 4, the internal weight portion 120 and the sole portion 108 form a recess r1 that is open toward the face side. In each vertical cross section, a backmost point tx of a cross-sectional contour line that defines the contour of the recess r1 is determined. Further, in each vertical cross section, a straight line X1 that passes through the point tx and extends in the up-down direction is determined. Furthermore, an intersection point ty between the straight line X1 and the upper surface of the internal weight portion 120 is determined. A straight line that connects the point tx and the point ty can be defined as a boundary between the base portion 122 and the protruding portion 124.

[0058] The protruding portion 124 includes an upper surface 124a and a lower surface 124b. The protruding portion 124 also includes a front end surface 124c. The front end surface 124c is a face-side end surface of the protruding portion 124. The front end surface 124c extends from the front edge of the upper surface 124a and the front edge of the lower surface 124b. The front end surface 124c does not have to be present. For example, when the protruding portion 124 has a pointed end, no front end surface 124c is formed.

[0059] The upper surface 124a is inclined such that it goes upward as its proximity to the face portion 104 increases. The lower surface 124b is inclined such that it goes upward as its proximity to the face portion 104 increases. The upper surface 124a is parallel to the lower surface 124b. The upper surface 124a does not have to be parallel to the lower surface 124b.

[0060] The base portion 122 includes an upper surface 122a. The upper surface 122a is inclined such that it goes upward as its proximity to the face portion 104 increases. The upper surface 122a may be a flat surface, or may be a curved surface. In the present embodiment, the upper surface 122a is a single flat surface. The upper surface 122a extends until it reaches the sole inner surface 108b of the sole portion 108, thereby terminating on the back side. The upper surface 122a is inclined such that it goes upward as its proximity to the protruding portion 124 increases. The entirety of the upper surface of the internal weight portion 120, including the upper surface 122a and the upper surface 124a, is inclined such that it goes upward as its proximity to the face portion 104 increases. In the internal weight portion 120, the upper surface 122a is flush with the upper surface 124a. The upper surface 122a and the upper surface 124a form a single flat surface. The upper surface 122a and the upper surface 124a do not have to be flush with each other.

[0061] With reference to FIG. 2, the internal weight portion 120 includes a toe-side portion 120T, a heel-side portion 120H, and the central portion 120M. The toe-side portion 120T is positioned on the toe side of the central portion 120M. The toe-side portion 120T is adjacent to the central portion 120M. The heel-side portion 120H is positioned on the heel side of the central portion 120M. The heel-side portion 120H is adjacent to the central portion 120M. The central portion 120M is positioned between the toe-side portion 120T and the heel-side portion 120H. The entirety of the toe-side portion 120T is positioned on the toe side relative to the face center C1. The entirety of the heel-side portion 120H is positioned on the heel side relative to the face center C1. The position of the face center C1 in the toe-heel direction is included in a toe-heel directional zone (a zone delimited only in the toe-heel direction) where the central portion 120M is disposed.

[0062] The central portion 120M includes both the base portion 122 and the protruding portion 124. As shown in FIG. 2, the toe-side portion 120T does not include the protruding portion 124. There is no gap in the up-down direction between the toe-side portion 120T and the sole inner surface 108b. The entirety of the toe-side portion 120T protrudes upward from the sole inner surface 108b. In the toe-side portion 120T, the space corresponding to the recess r1 (see FIG. 4) is filled with the material of the toe-side portion 120T. Additionally, the upper surface of the toe-side portion 120T is positioned on the upper side relative to the upper surface of the central portion 120M. In the internal weight portion 120, weight is largely allocated to the toe-side portion 120T.

[0063] As shown in FIG. 2, the heel-side portion 120H does not include the protruding portion 124. There is no gap in the up-down direction between the heel-side portion 120H and the sole inner surface 108b. The entirety of the heel-side portion 120H protrudes upward from the sole inner surface 108b. In the heel-side portion 120H, the space corresponding to the recess r1 (see FIG. 4) is filled with the material of the heel-side portion 120H. Additionally, the upper surface of the heel-side portion 120H is positioned on the upper side relative to the upper surface of the central portion 120M. In the internal weight portion 120, weight is largely allocated to the heel-side portion 120H. In the internal weight portion 120 as a whole, weight is effectively distributed to the toe-side portion and the heel-side portion. This weight distribution contributes to an increase in the moment of inertia of the head.

[0064] As shown in FIG. 2, the internal extending portion 110b is connected to the internal weight portion 120 (heel-side portion 120H). This configuration allows the internal weight portion 120 to be located at a further heel-side position, which can reduce the center of gravity distance of the head. Reducing the center of gravity distance facilitates club face rotation during a swing, thereby enhancing ball catchability of the head.

[0065] The term “good (enhanced) ball catchability” means that the striking face 104a is unlikely to open at impact with a golf ball. In a head having good ball catchability, the striking face 104a is likely to be square or slightly closed at impact with a golf ball. A head having good ball catchability efficiently transmits energy from the head to the struck ball, which can increase flight distance of the ball. The center of gravity distance refers to a distance between the shaft axis line and the head center of gravity.

[0066] A back-side edge 126 of the internal weight portion 120 (see FIG. 4) is positioned on the back side relative to the head center of gravity. On the other hand, as described above, the center of gravity of the protruding portion 124 is positioned on the face side relative to the head center of gravity. The center of gravity of the internal weight portion 120 is positioned on the face side relative to the head center of gravity. The center of gravity of the base portion 122 is positioned on the face side relative to the head center of gravity. As shown in FIG. 4, in the base portion 122, a portion whose upper surface 122a is inclined such that it descends toward the back side extends to reach a position located on the back side relative to the head center of gravity. This configuration increases the amount of weight allocated to the lower portion of the head 100. On the other hand, the center of gravity of the protruding portion 124 is located on the face side relative to the head center of gravity, which reduces the depth of the center of gravity. These configurations can lower the position of the sweet spot. The effect of lowering the sweet spot is further enhanced by positioning the center of gravity of the internal weight portion 120 on the face side relative to the head center of gravity. The effect of lowering the sweet spot is further enhanced by positioning the center of gravity of the base portion 122 on the face side relative to the head center of gravity. Note that the depth of the center of gravity refers to the distance in the face-back direction between the shaft axis line Z and the head center of gravity.

[0067] FIG. 8 is an enlarged view of the front view shown in FIG. 1A. FIG. 9 is an enlarged view of the cross-sectional view shown in FIG. 4.

[0068] The striking face 104a includes a bulge and a roll. The bulge refers to the curvature (roundness) in the horizontal direction. The bulge means the curvature shown in a cross section parallel to the ground plane HP (see FIG. 5). The roll refers to the curvature (roundness) in the vertical direction. The roll means the curvature shown in a vertical cross section (see FIG. 4).

[0069] The head 100 has a curvature radius R at the boundary between the striking face 104a and the crown outer surface 106a (see FIG. 4 and FIG. 8) (hereinafter, the curvature radius R is also referred to as crown-side curvature radius R). The curvature radius R is measured on a vertical cross-sectional contour line. The curvature radius R is determined in vertical cross sections taken at respective positions in the toe-heel direction. As shown in FIG. 8, the curvature radius R at a position spaced 15 mm apart from the face center C1 toward the toe side is represented by a curvature radius Rt. The curvature radius R at the position of the face center C1 is represented by a curvature radius Rc. See also FIG. 4 for the curvature radius Rc. The curvature radius R at a position spaced 15 mm apart from the face center C1 toward the heel side is represented by a curvature radius Rh. For the sake of easy understanding, the symbols “R”, “Rt”, “Rc”, “Rh” and the like are used throughout the present disclosure to distinguish among the above-described curvature radii and also serve as reference symbols in drawings. These curvature radii are measured in millimeters (mm).

[0070] The head 100 has a curvature radius S at the boundary between the striking face 104a and the sole outer surface 108a (see FIG. 4 and FIG. 8) (hereinafter, the curvature radius S is also referred to as sole-side curvature radius S). The curvature radius S is measured on a vertical cross-sectional contour line. The curvature radius S is determined in vertical cross sections taken at respective positions in the toe-heel direction. As shown in FIG. 8, the curvature radius S at a position spaced 15 mm apart from the face center C1 toward the toe side is represented by a curvature radius St. The curvature radius S at the position of the face center C1 is represented by a curvature radius Sc. See also FIG. 4 for the curvature radius Sc. The curvature radius S at a position spaced 15 mm apart from the face center C1 toward the heel side is represented by a curvature radius Sh. For the sake of easy understanding, the symbols “S”, “St”, “Sc”, “Sh” and the like are used throughout the present disclosure to distinguish among the above-described curvature radii and also serve as reference symbols in drawings. These curvature radii are measured in millimeters (mm).

[0071] The striking face 104a has a face height F. The face height F is measured in a vertical cross section. The face height F is measured in vertical cross sections taken at respective positions in the toe-heel direction. The face height F at a position spaced 15 mm apart from the face center C1 toward the toe side is represented by a face height Ft. The face height F at the position of the face center C1 is represented by a face height Fc. The face height F at a position spaced 15 mm apart from the face center C1 toward the heel side is represented by a face height Fh. For the sake of easy understanding, the symbols “F”, “Ft”, “Fc”, “Fh” and the like are used throughout the present disclosure to distinguish among the above-described face heights and also serve as reference symbols in drawings. These face heights are measured in millimeters (mm).

[0072] As shown in FIG. 9, the head 100 has a head thickness T. The head thickness T is measured in a vertical cross section. The head thickness T is measured in vertical cross sections taken at respective positions in the toe-heel direction. The head thickness T at a position spaced 15 mm apart from the face center C1 toward the toe side is represented by a head thickness Tt. The head thickness T at the position of the face center C1 is represented by a head thickness Tc (see FIG. 9). The head thickness T at a position spaced 15 mm apart from the face center C1 toward the heel side is represented by a head thickness Th. For the sake of easy understanding, the symbols “T”, “Tt”, “Tc”, “Th” and the like are used throughout the present disclosure to distinguish among the above-described head thicknesses and also serve as reference symbols in drawings. The symbols “Tt” and “Th” are not shown in the drawings. These head thicknesses are measured in millimeters (mm).

[0073] A region that extends from a position spaced 15 mm apart from the face center C1 toward the toe side to a position spaced 15 mm apart from the face center C1 toward the heel side has a high probability of striking a ball. This region is referred to as a main striking region.

[0074] The curvature radius R can be defined as follows. A vertical cross-sectional contour line includes a crown specific point that is defined as a point having a minimum curvature radius in a region located between the crown outer surface 106a and a point constituting the outer edge k1 on the crown side (hereinafter, a point constituting the outer edge k1 is referred to as an outer edge point). When the minimum curvature radius occurs not only at a specific point but continues in a portion having a length within the region, the crown specific point is defined as the midpoint of the path length of that portion. The midpoint is determined based on the path length measured following (along) the vertical cross-sectional contour line. A crown auxiliary point is disposed on the crown side of the crown specific point. The crown auxiliary point is positioned such that the crown specific point becomes the midpoint between the crown auxiliary point and the outer edge point. This midpoint is determined based on the path length measured following (along) the vertical cross-sectional contour line. That is, the path length between the crown specific point and the crown auxiliary point is equal to the path length between the outer edge point and the crown specific point. The curvature radius R can be defined as a radius of a circle passing through the three points: the outer edge point, the crown specific point, and the crown auxiliary point.

[0075] The curvature radius S can be defined as follows. A vertical cross-sectional contour line includes a sole specific point that is defined as a point having a minimum curvature radius in a region located between the sole outer surface 108a and a point (outer edge point) constituting the outer edge k1 on the sole side. When the minimum curvature radius occurs not only at a specific point but continues in a portion having a length within the region, the sole specific point is defined as the midpoint of the path length of that portion. The midpoint is determined based on the path length measured following (along) the vertical cross-sectional contour line. A sole auxiliary point is disposed on the sole side of the sole specific point. The sole auxiliary point is positioned such that the sole specific point becomes the midpoint between the sole auxiliary point and the outer edge point. This midpoint is determined based on the path length measured following (along) the vertical cross-sectional contour line. That is, the path length between the sole specific point and the sole auxiliary point is equal to the path length between the outer edge point and the sole specific point. The curvature radius S can be defined as a radius of a circle passing through the three points: the outer edge point, the sole specific point, and the sole auxiliary point.

[0076] The face height F can be defined as follows. The face height F can be defined as a distance between the crown-side outer edge point and the sole-side outer edge point (shortest distance between the two points in a vertical cross-sectional contour line) (see FIG. 9).

[0077] The head thickness T can be defined as follows. As shown in FIG. 9, a horizontal straight line L1 that is in contact with the upper-most point (also referred to as head upper-most point Jm) of a vertical cross-sectional contour line, and a horizontal straight line L2 that is in contact with the lower-most point of the vertical cross-sectional contour line are determined. A distance between the straight line L1 and the straight line L2 can be defined as the head thickness T. The straight lines L1 and L2 are parallel to the ground plane HP. The head thickness T is measured in the up-down direction. Accordingly, the head thickness T is equivalent to the maximum thickness of the head in a vertical cross section taken at each position in the toe-heel direction. The face-back directional position (position in the face-back direction) of the head upper-most point Jm at which a vertical cross-sectional contour line contacts the straight line L1 varies. In the main striking region, the position of the head upper-most point Jm in the face-back direction shifts toward the back side as the position of the head upper-most point Jm shifts toward the toe side.

[0078] In the head 100, the crown-side curvature radius R is not constant. The curvature radius R varies depending on its position in the toe-heel direction. The curvature radius R varies in a continuous manner. The head 100 satisfies the following relationship (a). The head 100 further satisfies the following relationship (a1).

[0079] (a) Rt>Rc≥Rh

[0080] (a1) Rt>Rc>Rh

[0081] In the head 100, the sole-side curvature radius S is not constant. The curvature radius S varies depending on its position in the toe-heel direction. The curvature radius S varies in a continuous manner. The head 100 does not satisfy the following relationship (b). The head 100 does not satisfy the following relationship (b1). The head 100 does not satisfy the following relationship (b2). The head 100 satisfies the following relationship (b3). In the head 100, the curvature radius St is smaller than the curvature radius Sc. In the head 100, the curvature radius Sc is smaller than the curvature radius Sh. The relationship (b3) can suppress the increase of the curvature radius St.

[0082] (b) St>Sc≥Sh

[0083] (b1) St>Sc>Sh

[0084] (b2) St<Sc>Sh

[0085] (b3) St<Sc<Sh

[0086] As to the head thickness T, the head 100 does not satisfy the following relationship (c). The head 100 satisfies the following relationship (c1). In the head 100, the head thickness Tt is smaller than the head thickness Tc. In the head 100, the head thickness Tc is greater than the head thickness Th.

[0087] (c) Tt>Tc>Th

[0088] (c1) Tt<Tc>Th

[0089] In the head 100 (fairway wood type head), the difference (Tt−Th) can be less than or equal to 5.0 mm, further can be less than or equal to 4.5 mm, and even further can be less than or equal to 4.0 mm. The difference (Tt−Th) can be greater than or equal to 1.0 mm, further can be greater than or equal 1.5 mm, and even further can be greater than or equal 2.0 mm.

[0090] As to the face height F, the head 100 satisfies the following relationship (d).

[0091] (d) Ft<Fc>Fh

[0092] In the head 100, the increase of the face height Ft is suppressed, and the face height Ft is similar in value to the face height Fh. The face height Ft is smaller than the face height Fc. The face height Ft is greater than the face height Fh. However, the face height Ft is substantially equal to the face height Fh. Alternatively, the face height Ft may be smaller than the face height Fh. The absolute value of the difference (Ft−Fh) can be less than or equal to 1.5 mm, further can be less than or equal to 1.0 mm, and even further can be less than or equal to 0.5 mm.

[0093] As to the ratio of the face height F to the head thickness T, the head 100 satisfies the following relationship (e).

[0094] (e) Ft / Tt<Fh / Th

[0095] Furthermore, the head 100 satisfies the following relationships (f) and (f1).

[0096] (f) Ft / Tt<Fc / Tc≤Fh / Th

[0097] (f1) Ft / Tt<Fc / Tc<Fh / Th

[0098] In the head 100, the curvature radius St is smaller than the curvature radius Rt. In the head 100, the curvature radius Sc is smaller than the curvature radius Rc. In the head 100, the curvature radius Sh is smaller than the curvature radius Rh. The head 100 is an example of a fairway wood type head and may have the following dimensions.

[0099] Crown-side curvature radius Rt: 12.33 mm

[0100] Crown-side curvature radius Rc: 10.11 mm

[0101] Crown-side curvature radius Rh: 7.72 mm

[0102] Sole-side curvature radius St: 3.25 mm

[0103] Sole-side curvature radius Sc: 3.47 mm

[0104] Sole-side curvature radius Sh: 3.63 mm

[0105] Face height Ft: 22.81 mm

[0106] Face height Fc: 24.46 mm

[0107] Face height Fh: 22.72 mm

[0108] Head thickness Tt: 36.37 mm

[0109] Head thickness Tc: 36.39 mm

[0110] Head thickness Th: 33.45 mm

[0111] By satisfying the following relationship (a) and / or relationship (b), and increasing the curvature radius Rt and / or curvature radius St on the toe side, the increase of the face height Ft is suppressed, and the following relationship (e) can be satisfied. In this configuration, since the boundary portion(s) having a large curvature radius (portion having the curvature radius Rt and / or portion having the curvature radius St) bends, and the head 100 has a small face height Ft, a load applied to the face portion is reduced when the head 100 strikes a ball at a toe-side position. This improves durability of the head (hereinafter, this advantageous effect is referred to as “toe durability improvement effect”). The small face height Ft can reduce the amount of bending of the face portion, which can lead to deterioration of rebound performance of the head 100. However, since the boundary portion(s) having a large curvature radius Rt and / or having a large curvature radius St bends, the overall amount of bending in the toe-side part of the head 100 can be maintained. Accordingly, the rebound performance can be maintained (hereinafter, this advantageous effect is referred to as “toe rebound performance maintaining effect”). On the other hand, the heel-side part of a head has a small face height Fh as a basic head structure, which is advantageous for durability. The head 100 can have a sufficient face height Fh by reducing the curvature radius Rh and / or the curvature radius Sh. Such a sufficient face height Fh leads to sufficient bending of the heel-side part of the face portion 104, which can enhance the rebound performance (hereinafter, this advantageous effect is referred to as “heel rebound performance improvement effect”). In addition, the viewable area of the striking face is not narrowed by maintaining the sufficient face height Fh on the heel side, which can provide a golfer with a feeling of relief when addressing a golf ball with the head 100. From these viewpoints, it is more preferable that the following relationship(s) (a1) and / or (b1) is satisfied.

[0112] (a) Rt>Rc≥Rh

[0113] (b) St>Sc≥Sh

[0114] (a1) Rt>Rc>Rh

[0115] (b1) St>Sc>Sh

[0116] (e) Ft / Tt<Fh / Th

[0117] The above-described advantageous effects are enhanced in actual shots with the head 100 by satisfying the above relationship(s) in the main striking region.

[0118] The present embodiment satisfies the above relationship (a) or (a1), and satisfies the above relationship (e). For this reason, the boundary portion on the crown side having a large curvature radius Rt bends when the head 100 strikes a ball at a toe-side position of the striking face, and the increase of the face height Ft on the toe side is suppressed. This reduces a load applied on the toe-side part of the face portion, and improves durability of the head (toe durability improvement effect). A small face height Ft can reduce the amount of bending of the face portion and can worsen the rebound performance. However, a portion having a curvature radius of Rt bends, and thus the overall amount of bending in the toe-side part of the head can be maintained. Accordingly, the rebound performance in the toe-side part of the head can be maintained (toe rebound performance maintaining effect). On the other hand, the heel-side part of a head usually has a small face height Fh, which is advantageous in durability. The head can have a sufficient face height Fh by reducing the curvature radius Rh. Such a sufficient face height Fh can bring about a sufficient bending in the heel-side part of the face portion, which can enhance the rebound performance (heel rebound performance improvement effect). These advantageous effects can improve the rebound performance and durability in the entirety of the face portion. In addition, the viewable area of the striking face is not reduced by maintaining the sufficient face height Fh in the heel-side part, which can provide a golfer with a feeling of relief when addressing a golf ball with the head 100.

[0119] The present embodiment satisfies the following relationship (f). Furthermore, the present embodiment satisfies the following relationship (f1). Accordingly, the advantageous effects brought by the above relationship (e) are further enhanced.

[0120] (f) Ft / Tt<Fc / Tc≤Fh / Th

[0121] (f1) Ft / Tt<Fc / Tc<Fh / Th

[0122] The present embodiment satisfies neither the relationship (b) nor (b1). A head according to another embodiment may satisfy the relationship (b) instead of the relationship (a). A head according to still another embodiment may satisfy the relationship (b1) instead of the relationship (a1). A head according to still another embodiment may satisfy both the relationships (a) and (b). A head according to still another embodiment may satisfy both the relationships (a1) and (b1). When the face height Ft is excessively small, the striking face looks narrow, which can reduce golfer's feeling of relief when addressing a golf ball with the head. From this viewpoint, when the relationship (a) is satisfied, it is preferable that the relationship (b) is not satisfied, and it is more preferable that the relationship (b2) or the relationship (b3) is satisfied. When the relationship (a1) is satisfied, it is preferable that the relationship (b1) is not satisfied, and it is more preferable that the relationship (b2) or the relationship (b3) is satisfied.

[0123] When a head satisfies the relationships (b) and (b1), the range of variation of the sole-side curvature radius S is wide, which tends to exert an increased effect on the shape of the sole surface. The shape of the sole surface influences the ground resistance of the head. From the viewpoint of flexibility in designing the shape of the sole surface, a head that satisfies neither the relationship (b) nor (b1) is preferable. On the other hand, when the relationship (b) or (b1) is satisfied, the relationship (e) can also be attained without needing to vary the curvature radius R. A variation of the curvature radius R tends to affect the appearance of the head as observed by a golfer addressing a golf ball with the head. When it is required that the appearance of the head, as viewed by a golfer addressing a golf ball with the head, be the same as that of a conventional head, the head may satisfy the relationship (b) or (b1).

[0124] As to the distribution of golf ball impact points on the face surface, the face surface has a higher density of golf ball impact points in a region extending from the heel lower side to the toe upper side. The striking face can be formed in such a region having a high density of golf ball impact points by satisfying the relationship (b) or (b1).

[0125] A position spaced 15 mm apart from the face center C1 toward the toe side is also referred to as a toe reference position. The position of the face center C1 is also referred to as a center position. A position spaced 15 mm apart from the face center C1 toward the heel side is also referred to as a heel reference position. The main striking region is a region that extends from the heel reference position to the toe reference position.

[0126] The curvature radius R continuously varies in the main striking region. In this main striking region, the curvature radius R increases toward the toe side. The curvature radius S may continuously vary in the main striking region. This configuration can increase the curvature radius S toward the toe side in the main striking region.

[0127] In a fairway wood type head (present embodiment) and in a hybrid type head, the sole-side curvature radius S is smaller than the crown-side curvature radius R. That is, the curvature radius St is smaller than the curvature radius Rt, the curvature radius Sc is smaller than the curvature radius Rc, and the curvature radius Sh is smaller than the curvature radius Rh. Fairway wood type heads and hybrid type heads are often used to strike a ball that is placed directly on turf without being teed up. When the curvature radius S is large, a distance in the vertical direction between the ground surface and the leading edge tends to be large. This tends to cause missed shots (so called tops in Japanese, or thin shots in English) when striking a ball placed directly on the ground surface (such as turf). The present embodiment can prevent such missed shots.

[0128] From the viewpoint of preventing the above-described missed shots, the following condition is preferable for fairway wood type heads and hybrid type heads. The curvature radius St is preferably less than or equal to 7.0 mm, more preferably less than or equal to 6.0 mm, still more preferably less than or equal to 5.0 mm, and even more preferably less than or equal to 4.0 mm. From the viewpoint of suppressing the increase of the face height Ft, the curvature radius St is preferably greater than or equal to 1.5 mm, more preferably greater than or equal to 2.0 mm, and still more preferably greater than or equal to 2.5 mm.

[0129] From the viewpoint of preventing the above-described missed shots, the following condition is preferable for fairway wood type heads and hybrid type heads. The curvature radius Sc is preferably less than or equal to 7.0 mm, more preferably less than or equal to 6.0 mm, still more preferably less than or equal to 5.0 mm, and even more preferably less than or equal to 4.0 mm. From the viewpoint of ground resistance, the curvature radius Sc is preferably greater than or equal to 1.5 mm, more preferably greater than or equal to 2.0 mm, and still more preferably greater than or equal to 2.5 mm.

[0130] From the viewpoints of preventing the above-described missed shots and maintaining a sufficient face height Fh, the following condition is preferable for fairway wood type heads and hybrid type heads. The curvature radius Sh is preferably less than or equal to 7.0 mm, more preferably less than or equal to 6.0 mm, still more preferably less than or equal to 5.0 mm, and even more preferably less than or equal to 4.0 mm. From the viewpoint of ground resistance, the curvature radius Sh is preferably greater than or equal to 1.5 mm, more preferably greater than or equal to 2.0 mm, and still more preferably greater than or equal to 2.5 mm.

[0131] A driver head can have a larger curvature radius S compared to the curvature radii S of a fairway wood type head and a hybrid type head. A driver head strikes a ball that is teed up, and thus is less likely to cause the above-described missed shots. Additionally, a driver head has a relatively large face height F, and thus there is a large room to reduce the face height F. From these viewpoints, it is preferable to enhance the rebound performance of driver heads by having a relatively larger curvature radius S and increasing the amount of bending in the boundary portion on the sole. In driver heads, the curvature radius St, the curvature radius Sc and the curvature radius Sh can be greater than or equal to 7.5 mm, further can be greater than or equal to 8.0 mm, and still further can be greater than or equal to 8.5 mm. From the viewpoint of preventing an excessively small face height Ft, the curvature radius St, the curvature radius Sc, and the curvature radius Sh of driver heads can be less than or equal to 12.0 mm, further can be less than or equal to 11.0 mm, and still further can be less than or equal to 10.0 mm.

[0132] From the viewpoint of preventing the above-described missed shots, the ratio Rt / St is preferably greater than or equal to 1.5, more preferably greater than or equal to 2.0, and still more preferably greater than or equal to 2.5. Considering preferable values of the curvature radius St and the face height Ft, the ratio Rt / St is preferably less than or equal to 5.0, more preferably less than or equal to 4.5, and still more preferably less than or equal to 4.0.

[0133] From the viewpoint of preventing the above-described missed shots, the ratio Rc / Sc is preferably greater than or equal to 1.5, more preferably greater than or equal to 2.0, and still more preferably greater than or equal to 2.5. Considering preferable values of the curvature radius Sc and the face height Fc, the ratio Rc / Sc is preferably less than or equal to 5.0, more preferably less than or equal to 4.5, and still more preferably less than or equal to 4.0.

[0134] From the viewpoint of preventing the above-described missed shots, the ratio Rh / Sh is preferably greater than or equal to 1.0, more preferably greater than or equal to 1.5, and still more preferably greater than or equal to 2.0. Considering preferable values of the curvature radius Sh and the face height Fh, the ratio Rh / Sh is preferably less than or equal to 4.5, more preferably less than or equal to 4.0, and still more preferably less than or equal to 3.5.

[0135] Rt / Rh is a ratio of the curvature radius Rt on the toe side to the curvature radius Rh on the heel side. From the viewpoints of the toe durability improvement effect, the toe rebound performance maintaining effect, and the heel rebound performance improvement effect, the ratio Rt / Rh is preferably greater than or equal to 1.20, more preferably greater than or equal to 1.25, still more preferably greater than or equal to 1.30, still more preferably greater than or equal to 1.35, and even more preferably greater than or equal to 1.40. An excessively large curvature radius Rt can lead to an excessively small face height Ft, which can worsen golfer's feeling of relief when addressing a golf ball with the head. From this viewpoint, Rt / Rh is preferably less than or equal to 1.80, more preferably less than or equal to 1.75, and still more preferably less than or equal to 1.70.

[0136] When the relationship (a) or (a1) is satisfied and Rt / Rh is great, St / Sh is preferably small. When both Rt / Rh and St / Sh are great, the face height Ft can be excessively small. An excessively small face height Ft can lead to deterioration of golfer's feeling of relief when addressing a golf ball with the head. From this viewpoint, when Rt / Rh falls within the above-described preferable range of greater than or equal to 1.20, St / Sh is preferably less than or equal to 1.15, more preferably less than or equal to 1.10, and still more preferably less than or equal to 1.05. An excessively small curvature radius St can increase the face height Ft, which can lead to deterioration of the toe durability improvement effect. From this viewpoint, St / Sh is preferably greater than or equal to 0.80, more preferably greater than or equal to 0.85, and still more preferably greater than or equal to 0.90.

[0137] Ft / Fh is a ratio of the face height Ft on the toe side to the face height Fh on the heel side. From the viewpoints of the toe durability improvement effect, the toe rebound performance maintaining effect, and the heel rebound performance improvement effect, the ratio Ft / Fh is preferably less than or equal to 1.15, more preferably less than or equal to 1.12, still more preferably less than or equal to 1.09, and even more preferably less than or equal to 1.06. An excessively large curvature radius Rt or an excessively large curvature radius St can cause an excessively small face height Ft, which can lead to deterioration of golfer's feeling of relief when addressing a golf ball with the head. From this viewpoint, the ratio Ft / Fh is preferably greater than or equal to 0.85, more preferably greater than or equal to 0.90, and still more preferably greater than or equal to 0.95.

[0138] From the viewpoints of: satisfying the relationship (a) or (a1), and the relationship (e); enhancing the advantageous effects brought by these relationships; and conforming to the specifications of respective head types, the curvature radius R can be set to fall within the following ranges. In the following descriptions, (x) shows a preferable range, (y) shows a more preferable range, and (z) shows an even more preferable range.Curvature Radius Rt of a Driver Head

[0139] (x) greater than or equal to 9.5 mm and less than or equal to 13.5 mm

[0140] (y) greater than or equal to 10.0 mm and less than or equal to 13.0 mm

[0141] (z) greater than or equal to 10.5 mm and less than or equal to 12.5 mmCurvature Radius Rc of a Driver Head

[0142] (x) greater than or equal to 7.5 mm and less than or equal to 11.5 mm

[0143] (y) greater than or equal to 8.0 mm and less than or equal to 11.0 mm

[0144] (z) greater than or equal to 8.5 mm and less than or equal to 10.5 mmCurvature Radius Rh of a Driver Head

[0145] (x) greater than or equal to 6.0 mm and less than or equal to 10.0 mm

[0146] (y) greater than or equal to 6.5 mm and less than or equal to 9.5 mm

[0147] (z) greater than or equal to 7.0 mm and less than or equal to 9.0 mmCurvature Radius Rt of a Fairway Wood Type Head

[0148] (x) greater than or equal to 10.0 mm and less than or equal to 14.0 mm

[0149] (y) greater than or equal to 10.5 mm and less than or equal to 13.5 mm

[0150] (z) greater than or equal to 11.0 mm and less than or equal to 13.0 mmCurvature Radius Rc of a Fairway Wood Type Head

[0151] (x) greater than or equal to 8.0 mm and less than or equal to 12.0 mm

[0152] (y) greater than or equal to 8.5 mm and less than or equal to 11.5 mm

[0153] (z) greater than or equal to 9.0 mm and less than or equal to 11.0 mmCurvature Radius Rh of a Fairway Wood Type Head

[0154] (x) greater than or equal to 6.0 mm and less than or equal to 10.0 mm

[0155] (y) greater than or equal to 6.5 mm and less than or equal to 9.5 mm

[0156] (z) greater than or equal to 7.0 mm and less than or equal to 9.0 mmCurvature Radius Rt of a Hybrid Type Head

[0157] (x) greater than or equal to 7.5 mm and less than or equal to 11.5 mm

[0158] (y) greater than or equal to 8.0 mm and less than or equal to 11.0 mm

[0159] (z) greater than or equal to 8.5 mm and less than or equal to 10.5 mmCurvature Radius Rc of a Hybrid Type Head

[0160] (x) greater than or equal to 6.0 mm and less than or equal to 10.0 mm

[0161] (y) greater than or equal to 6.5 mm and less than or equal to 9.5 mm

[0162] (z) greater than or equal to 7.0 mm and less than or equal to 9.0 mmCurvature Radius Rh of a Hybrid Type Head

[0163] (x) greater than or equal to 4.5 mm and less than or equal to 8.5 mm

[0164] (y) greater than or equal to 5.0 mm and less than or equal to 8.0 mm

[0165] (z) greater than or equal to 5.5 mm and less than or equal to 7.5 mm

[0166] From the viewpoints of: satisfying the relationship (e), (f), or (f1); enhancing the advantageous effects brought by these relationships; and conforming to the specifications of respective head types, the ratio (F / T) can be set to fall within the following ranges. In the following descriptions, (x) shows a preferable range, (y) shows a more preferable range, and (z) shows an even more preferable range.Ft / Tt of a Driver Head

[0167] (x) greater than or equal to 0.61 and less than or equal to 0.71

[0168] (y) greater than or equal to 0.62 and less than or equal to 0.70

[0169] (z) greater than or equal to 0.63 and less than or equal to 0.69Fc / Tc of a Driver Head

[0170] (x) greater than or equal to 0.62 and less than or equal to 0.72

[0171] (y) greater than or equal to 0.63 and less than or equal to 0.71

[0172] (z) greater than or equal to 0.64 and less than or equal to 0.70Fh / Th of a Driver Head

[0173] (x) greater than or equal to 0.64 and less than or equal to 0.74

[0174] (y) greater than or equal to 0.65 and less than or equal to 0.73

[0175] (z) greater than or equal to 0.66 and less than or equal to 0.72Ft / Tt of a Fairway Wood Type Head

[0176] (x) greater than or equal to 0.58 and less than or equal to 0.68

[0177] (y) greater than or equal to 0.59 and less than or equal to 0.67

[0178] (z) greater than or equal to 0.60 and less than or equal to 0.66Fc / Tc of a Fairway Wood Type Head

[0179] (x) greater than or equal to 0.62 and less than or equal to 0.72

[0180] (y) greater than or equal to 0.63 and less than or equal to 0.71

[0181] (z) greater than or equal to 0.64 and less than or equal to 0.70Fh / Th of a Fairway Wood Type Head

[0182] (x) greater than or equal to 0.63 and less than or equal to 0.73

[0183] (y) greater than or equal to 0.64 and less than or equal to 0.72

[0184] (z) greater than or equal to 0.65 and less than or equal to 0.71Ft / Tt of a Hybrid Type Head

[0185] (x) greater than or equal to 0.68 and less than or equal to 0.78

[0186] (y) greater than or equal to 0.69 and less than or equal to 0.77

[0187] (z) greater than or equal to 0.70 and less than or equal to 0.76Fc / Tc of a Hybrid Type Head

[0188] (x) greater than or equal to 0.71 and less than or equal to 0.81

[0189] (y) greater than or equal to 0.72 and less than or equal to 0.80

[0190] (z) greater than or equal to 0.73 and less than or equal to 0.79Fh / Th of a Hybrid Type Head

[0191] (x) greater than or equal to 0.72 and less than or equal to 0.82

[0192] (y) greater than or equal to 0.73 and less than or equal to 0.81

[0193] (z) greater than or equal to 0.74 and less than or equal to 0.80

[0194] Examples of general specifications for a driver head (including mini driver heads treated equally with a driver head) include the following (1a) to

[0195] (1e):

[0196] (1a) a curved striking face;

[0197] (1b) a hollow structure;

[0198] (1c) a head volume of greater than or equal to 300 cm3 and less than or equal to 470 cm3;

[0199] (1d) a real loft angle of greater than or equal to 7 degrees and less than or equal to 13 degrees; and

[0200] (1e) presence of a crown.

[0201] Examples of club numbers of fairway wood type heads include 3-wood (W #3), 4-wood (W #4 ), 5-wood (W #5), 7-wood (W #7 ), 9-wood (W #9), 11-wood (W #11), and 13-wood (W #13). Examples of general specifications for a fairway wood type head include the following (2a) to (2e):

[0202] (2a) a curved striking face;

[0203] (2b) a hollow structure;

[0204] (2c) a head volume of greater than or equal to 100 cm3 and less than 300 cm3;

[0205] (2d) a real loft angle of greater than 13 degrees and less than or equal to 33 degrees; and

[0206] (2e) presence of a crown.

[0207] Examples of club numbers of hybrid type heads include 3-hybrid (H3), 4-hybrid (H4), 5-hybrid (H5), and 6-hybrid (H6). Examples of general specifications for a hybrid type head include the following (3a) to (3e):

[0208] (3a) a curved striking face;

[0209] (3b) a hollow structure;

[0210] (3c) a head volume of greater than or equal to 90 cm3 and less than or equal to 140 cm3;

[0211] (3d) a real loft angle of greater than or equal to 15 degrees and less than or equal to 33 degrees; and

[0212] (3e) presence of a crown.

[0213] Hybrid type heads are also referred to as utility type heads in Japan. Hybrid type heads may be classified into wood type or iron type. An iron-type hybrid head does not include a crown.

[0214] A head that includes a crown, has a loft angle (real loft angle) of greater than 13 degrees, and has a head volume of less than 300 cm3 can be classified as a fairway wood type head or a hybrid type head. The ratio W1 / W2 can be used to distinguish between a fairway wood type head and a hybrid type head. A double-headed arrow W1 in FIG. 9 indicates the face-back directional width of the head 100 at the position of the face center C1. A double-headed arrow W2 in FIG. 8 indicates the toe-heel directional width of the head 100. The ratio W1 / W2 of a hybrid type head is less than 0.65. The ratio W1 / W2 of a fairway wood type head is greater than or equal to 0.65. A head that includes a crown and has a head volume of greater than or equal to 300 cm3 can be classified as a driver head.

[0215] FIG. 10 is a partially enlarged view of FIG. 4. FIG. 11 is a partially enlarged view of FIG. 5.

[0216] A weld bead wb is formed at a boundary between the face member f1 and the body member b1 where the face member f1 is welded to the body member b1 (hereinafter also referred to as a welded portion). The weld bead wb is formed on the inner surface of the head 100. The weld bead wb juts from the inner surface of the head 100. In FIG. 10 and FIG. 11, the weld bead wb is indicated in solid black. Although the weld bead wb actually has an irregular cross-sectional shape, the cross-sectional shape of the weld bead wb is schematically shown as a semicircle in FIG. 10 and FIG. 11. Note that in the cross-sectional views of FIG. 4 to FIG. 7 and FIG. 9, the weld bead wb is omitted.

[0217] The face member f1 is joined to the body member b1 by welding. There is no limitation on the method of welding. Examples of the welding method include laser welding, arc welding, gas welding, and resistance welding. A filler material (such as a welding rod) may or may not be used. In the present embodiment, the welding is performed by laser welding. The weld bead wb may be formed only of a base material(s), may be formed only of a filler material, or may be formed of both a base material(s) and a filler material. In the present embodiment, no filler material is used, and the weld bead wb is formed of base materials (the body member b1 and the face member f1) that have been melted and solidified. The welding is performed from the outside of the head 100. The weld bead formed on the outer surface of the head 100 is removed by polishing.

[0218] As shown in FIG. 10 and FIG. 11, an outer surface reference line CV1 that passes through the face center C1 and extends along the striking face 104a is determined in each of the radial cross sections. When the striking face 104a is a curved surface, the outer surface reference line CV1 is a curved line. In each radial cross section, the cross-sectional contour line of the striking face 104a has a point C2 that is spaced 1 mm apart from the face center C1 toward one side and a point C3 that is spaced 1 mm apart from the face center C1 toward the other side. The 1 mm distance is a path length measured following (along) the cross-sectional contour line of the striking face 104a. An arc of a circle that passes through the three points C1, C2, and C3 can be defined as the outer surface reference line CV1.

[0219] The normal line N1 to the striking face 104a at the face center C1 intersects the face inner surface 104b. An intersection point C4 between the normal line N1 and the face inner surface 104b is defined. In each radial cross section, the outer surface reference line CV1 is shifted in parallel to a position passing through the intersection point C4, whereby an inner surface reference line CV2 is determined. That is, the inner surface reference line CV2 is a line passing through the intersection point C4 and parallel to the outer surface reference line CV1.

[0220] The rearward extending portion E1 can be defined as a portion that extends toward the back side from the inner surface reference line CV2. A length D1 of the rearward extending portion E1 can be measured from the inner surface reference line CV2. The length D1 of the rearward extending portion E1 is measured in the direction of the normal line N1. The length D1 of the rearward extending portion E1 is measured in each of the radial cross sections.

[0221] In the radial cross section shown in FIG. 10, the face member f1 includes the rearward extending portion E1 extending from the outer edge of the face portion 104 toward the back side. The rearward extending portion E1 includes the sole-side rearward extending portion Es disposed in the sole-side portion of the face member f1. In the radial cross section shown in FIG. 10, the rearward extending portion E1 is not disposed in the crown-side portion of the face member f1. The length D1 of the rearward extending portion E1 is zero in the crown-side portion of the face member f1. The crown-side edge portion G1 formed by the absence of the rearward extending portion E1 is disposed in the crown-side portion of the face member f1. The entirety of the crown-side edge portion G1 is positioned between the outer surface reference line CV1 and the inner surface reference line CV2.

[0222] In the radial cross section shown in FIG. 11, the face member f1 includes the rearward extending portion E1 extending from the outer edge of the face portion 104 toward the back side. The rearward extending portion E1 includes the toe-side rearward extending portion Et disposed in the toe-side portion of the face member f1. In the radial cross section shown in FIG. 11, the rearward extending portion E1 is not disposed in the heel-side portion of the face member f1. At the cross-sectional position of FIG. 11 (the position of line B-B in FIG. 1A), the rearward extending portion E1 is not present due to the presence of the beveled portion 119. The rearward extending portion E1 (heel-side rearward extending portion Eh) is present at a position below the cross-sectional position of FIG. 11 (see FIG. 3).

[0223] Referring to FIG. 3, the length D1 of the rearward extending portion E1 in the toe-side portion of the face member f1 decreases toward the crown side (upward). That is, the length D1 of the toe-side rearward extending portion Et decreases toward the crown side (upward). The length D1 of the rearward extending portion E1 in the heel-side portion of the face member f1 decreases toward the crown side (upward). That is, the length D1 of the heel-side rearward extending portion Eh decreases toward the crown side (upward).

[0224] FIG. 12 is a partially enlarged view of FIG. 10. The head 100 has a wall thickness t1. The wall thickness t1 is measured in a direction that is normal to the outer surface of the head 100. The wall thickness t1 is defined as the distance from the head inner surface to the head outer surface.

[0225] From the viewpoint of strength, the wall thickness t1 of the face portion 104 can be greater than or equal to 1.2 mm, further can be greater than or equal to 1.3 mm, and even further can be greater than or equal to 1.4 mm. From the viewpoint of rebound performance, the wall thickness t1 of the face portion 104 can be less than or equal to 4.0 mm, further can be less than or equal to 3.8 mm, and even further can be less than or equal to 3.6 mm.

[0226] The wall thickness t1 of the head 100 is increased at the welded portion between the face member f1 and the body member b1 because of the presence of the weld bead wb. The weld bead wb locally enhances the rigidity of the head 100.

[0227] A portion of the weld bead wb positioned on the crown side (in the crown region CR), which is hereinafter referred to as a weld bead wb1, is connected to the crown-side edge portion G1. The weld bead wb1 has an end point 130 on the body side (hereinafter also referred to as a body-side end point 130). The wall thickness t1 at the end point 130 is referred to as a wall thickness t10. Preferably, the wall thickness t10 is greater than or equal to 0.7 mm and less than or equal to 1.0 mm. The wall thickness t10 is smaller than a width LG of the crown-side edge portion G1. The width LG is measured in the vertical cross section. The wall thickness t10 is greater than the wall thickness t1 of the sole-side rearward extending portion Es. The head 100 includes a wall thickness varying portion 132 in which the wall thickness t1 continuously decreases from the body-side end point 130 of the weld bead wb1 toward the back side. The face-back directional length of the wall thickness varying portion 132 can be greater than or equal to 3 mm and less than or equal to 20 mm.

[0228] In the face member f1, the entirety of the edge of the rearward extending portion E1 and the crown-side edge portion G1 lie on the same flat plane PL. The edge of the sole-side rearward extending portion Es, the edge of the toe-side rearward extending portion Et, the edge of the heel-side rearward extending portion Eh, and the crown-side edge portion G1 lie on the same flat plane PL (see FIG. 12 and FIG. 5 to FIG. 7). The joint surface 118 of the sole-side rearward extending portion Es, the joint surface 118 of the toe-side rearward extending portion Et, the joint surface 118 of the heel-side rearward extending portion Eh, and the crown-side edge portion G1 lie on the same flat plane PL. The entirety of the joint surface 118 extends on the flat plane PL. The crown-side edge portion G1 extends on the flat plane PL.

[0229] When the flat plane PL is laid horizontally and the face member f1 is placed on this horizontal flat plane PL, the edge of the sole-side rearward extending portion Es, the edge of the toe-side rearward extending portion Et, the edge of the heel-side rearward extending portion Eh, and the crown-side edge portion G1 abut against the horizontal flat plane PL. In this state, of the periphery of the face member f1, only the beveled portion 119 does not abut against the horizontal flat plane PL.

[0230] The edge of the body member b1 also lies on the same flat plane PL. That is, the entirety of the joint surface 116 of the body member b1 lies on the same flat plane PL. The joint surface 116 extends on the flat plane PL.

[0231] The head 100 exhibits the following advantageous effects.

[0232] The face member f1 includes the entirety of the face portion 104 (striking face 104a). Although the welded portion tends to exhibit increased rigidity, no welded portion is present in the face portion 104 (striking face 104a). This configuration facilitates bending of the entirety of the face portion 104, thereby enhancing the rebound performance of the head 100.

[0233] From the viewpoint of preventing deformation and breakage during the welding process, it is necessary that the welded portion has a sufficient wall thickness t1. Additionally, the welded portion having an increased wall thickness t1 attains an increased joining strength. However, when welding is performed at a crown-side rearward extending portion E1 and the wall thickness t1 of the rearward extending portion E1 is increased, the center of gravity of the head 100 tends to be located at a higher position. On the other hand, when welding is performed at the crown-side edge portion G1 on the crown side of the face member f1 as in the present embodiment, the welded portion is located at a position originally having a relatively large wall thickness t1 (a transition portion from the face portion 104 to the crown portion 106). Accordingly, it is not necessary for the head 100 to thicken a crown-side rearward extending portion E1, unlike conventional heads. This configuration enables the head 100 to include a crown-side portion having a reduced weight, and to have a lowered center of gravity. The lowered center of gravity of the head 100 brings the impact point of a ball closer to the sweet spot, particularly when striking a ball placed directly on the ground, which can improve the rebound performance of the head 100.

[0234] The width LG of the crown-side edge portion G1 is larger than the wall thickness t1 of the sole-side rearward extending portion Es. This configuration enhances the joining strength of the welded portion on the crown side. When a head includes a rearward extending portion E1 on the crown side and the welded portion has a wall thickness t1 that is as thick as the width LG, the rearward extending portion E1 has a large thickness, causing the center of gravity of the head 100 to tend to be located at a higher position. Eliminating the rearward extending portion E1 on the crown side and performing welding at the crown-side edge portion G1 reduces the weight of the crown-side portion of the head 100 while increasing the width LG of the welded portion.

[0235] As described above, the head 100 includes the wall thickness varying portion 132 having a wall thickness t1 that continuously decreases rearward from the body-side end point 130 of the weld bead wb1 on the crown side. The wall thickness varying portion 132 can reduce the weight of the crown-side portion of the head 100 while increasing the width LG of the welded portion. The reference numeral 134 shown in FIG. 10 indicates a point where the wall thickness t1 of the wall thickness varying portion 132 is equal to (the minimum value of) the wall thickness t1 of the sole-side rearward extending portion Es. The wall thickness t1 of the crown portion 106 on the back side relative to the point 134 is thinner than the wall thickness t1 of the sole-side rearward extending portion Es. From the viewpoint of lowering the position of the center of gravity of the head 100, a distance D2 from the inner surface reference line CV2 to the point 134 is preferably smaller than the length D1 of the sole-side rearward extending portion Es, and more preferably smaller than half the length D1. From the viewpoint of lowering the position of the center of gravity of the head 100, the distance D2 from the inner surface reference line CV2 to the point 134 is preferably less than or equal to 3 mm, more preferably less than or equal to 2 mm, and even more preferably less than or equal to 1 mm. The distance D2 may be zero. The point 134 may be positioned on the front side relative to the inner surface reference line CV2. The distance D2 is measured in the direction of the normal line N1 to the striking face 104a at the face center C1.

[0236] When a head does not include a rearward extending portion E1 on the crown side and includes the rearward extending portion E1 on the sole side, and the edge of the rearward extending portion E1 on the sole side and the crown-side edge portion G1 lie on the same flat plane PL, the flat plane PL is oriented obliquely relative to the direction normal to the head outer surface (see FIG. 12). This configuration can increase the width LG of the crown-side edge portion G1, and can enhance the welding strength.

[0237] From the viewpoint of rebound performance, the length D1 of the sole-side rearward extending portion Es is preferably greater than or equal to 6 mm, more preferably greater than or equal to 7 mm, and even more preferably greater than or equal to 8 mm. From the viewpoint of welding workability, the length D1 of the sole-side rearward extending portion Es is preferably less than or equal to 20 mm, more preferably less than or equal to 15 mm, and even more preferably less than or equal to 12 mm.

[0238] A weld bead (jutted portion) is formed at the welded portion on the outer surface of the head 100. The weld bead needs to be removed by polishing. If the polished portion forms the contour line of the head 100 when addressing a golf ball with the head, variations in the contour shape among individual heads 100 increase. In the head 100, the sole-side rearward extending portion Es, the toe-side rearward extending portion Et, and the heel-side rearward extending portion Eh are disposed at positions that form the contour line of the head 100 when addressing a golf ball. This configuration eliminates the need for welding at positions forming the contour line of the head 100, thereby suppressing variations in the contour shape among individual heads 100. By reducing such variations, the sense of incongruity in the appearance of the striking face 104a when addressing a golf ball can be lessened. Note that the upper edge portion of the face portion 104 does not form the contour line of the head 100 when addressing a golf ball. Accordingly, polishing the weld bead at the crown-side edge portion G1 does not affect the contour shape of the head 100.

[0239] In the face member f1, the entirety of the edge of the rearward extending portion E1 and the crown-side edge portion G1 lie on the same flat plane PL. That is, the rear end of the face member f1, which is the portion to be welded, lies on the same flat plane PL. This configuration facilitates processing of the edge portion of the face member f1. For example, the edge portion of the face member f1 can be cut along a flat plane by milling. Accordingly, this configuration facilitates processing and enhances processing accuracy. As a result, the face member f1 and the body member b1 abut each other with high accuracy, which can reduce variations in shape among individual finished heads 100. Similarly, the front end (joint surface 116) of the body member b1 also lies on the same flat plane PL. The body member b1 exhibits the same advantageous effects as the face member f1.

[0240] The center of gravity of the internal weight portion 120 is positioned on the face side relative to the head center of gravity. Additionally, as shown in FIG. 4, in the base portion 122, a portion whose upper surface 122a is inclined such that it descends toward the back side extends to reach a position located on the back side relative to the head center of gravity. This configuration increases the amount of weight allocated to the lower portion of the head 100. On the other hand, the center of gravity of the protruding portion 124 is located on the face side relative to the head center of gravity, which reduces the depth of the center of gravity. These configurations can lower the position of the sweet spot. The lowered sweet spot brings the impact point of a ball closer to the sweet spot when striking a ball placed directly on the ground. This can improve the rebound performance of the head 100.

[0241] Regarding the above-described embodiments, the following clauses are disclosed.

[0242] [Clause 1]

[0243] A golf club head including: a hollow interior, a face portion that includes a striking face as a front surface, a crown portion, and a sole portion, wherein

[0244] the golf club head includes a body member that includes an opening, and a face member that includes the face portion, that covers the opening, and that is welded to the body member,

[0245] the face member includes a rearward extending portion that extends from an outer edge of the face portion toward a back side,

[0246] the rearward extending portion includes a sole-side rearward extending portion disposed in a sole-side portion of the face member, a toe-side rearward extending portion disposed in a toe-side portion of the face member, and a heel-side rearward extending portion disposed in a heel-side portion of the face member, and

[0247] the face member also includes a crown-side edge portion formed by an absence of the rearward extending portion in a crown-side portion of the face member.

[0248] [Clause 2]

[0249] The golf club head according to clause 1, wherein an edge of the sole-side rearward extending portion, an edge of the toe-side rearward extending portion, an edge of the heel-side rearward extending portion, and the crown-side edge portion lie on a same flat plane.

[0250] [Clause 3]

[0251] The golf club head according to clause 1 or 2, wherein

[0252] the golf club head includes a weld bead formed at a boundary between the crown-side edge portion and the body member, and

[0253] the body member has a wall thickness at a body-side end point of the weld bead of greater than or equal to 0.7 mm and less than or equal to 1.0 mm.

[0254] [Clause 4]

[0255] The golf club head according to any one of clauses 1 to 3, wherein the sole-side rearward extending portion has a length of less than or equal to 20 mm.

[0256] [Clause 5]

[0257] The golf club head according to any one of clauses 1 to 4, wherein the golf club head is a fairway wood type head.LIST OF REFERENCE SYMBOLS100 Golf club head

[0259] 104 Face portion

[0260] 104a Striking face

[0261] 104b Face inner surface

[0262] 106 Crown portion

[0263] 108 Sole portion

[0264] 110 Hosel portion

[0265] 112 Hosel hole

[0266] 120 Internal weight portion

[0267] 122 Base portion of the internal weight portion

[0268] 124 Protruding portion of the internal weight portion

[0269] f1 Face member

[0270] b1 Body member

[0271] h1 Hollow interior

[0272] wb Weld bead

[0273] k1 Outer edge of the striking face

[0274] CR Crown region

[0275] SL Sole region

[0276] TE Toe region

[0277] HL Heel region

[0278] C1 Face center

[0279] E1 Rearward extending portion

[0280] Es Sole-side rearward extending portion

[0281] Et Toe-side rearward extending portion

[0282] Eh Heel-side rearward extending portion

[0283] R Curvature radius at the boundary between the striking face and the crown outer surface

[0284] Rt Curvature radius R at a position spaced 15 mm apart from the face center toward the toe side

[0285] Rc Curvature radius R at the position of the face center

[0286] Rh Curvature radius R at a position spaced 15 mm apart from the face center toward the heel side

[0287] S Curvature radius at the boundary between the striking face and the sole outer surface

[0288] St Curvature radius S at a position spaced 15 mm apart from the face center toward the toe side

[0289] Sc Curvature radius S at the position of the face center

[0290] Sh Curvature radius S at a position spaced 15 mm apart from the face center toward the heel side

[0291] The above descriptions are merely illustrative and various modifications can be made without departing from the principles of the present disclosure.

[0292] The terminology used in the description of the various described embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The use of the terms “a”, “an”, “the”, and similar referents in the context of throughout this disclosure (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. As used throughout this

[0293] disclosure, the word “may” is used in a permissive sense (i.e., meaning “having the potential to”), rather than the mandatory sense (i.e., meaning “must”). Similarly, as used throughout this disclosure, the terms “comprising,”“having,”“including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted.

[0294] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, sections, steps, processings, and / or operations, these elements, components, regions, layers, sections, steps, processings, and / or operations should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer, section, step, processing, or operation from another element, component, region, layer, section, step, processing, or operation. Terms such as “first,”“second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer, section, step, processing, or operation discussed herein could be termed a second element, component, region, layer, section, step, processing, or operation without departing from the teachings of the example embodiments.

Claims

1. A golf club head comprising: a hollow interior, a face portion that includes a striking face as a front surface, a crown portion, and a sole portion, whereinthe golf club head includes a body member that includes an opening, and a face member that includes the face portion, that covers the opening, and that is welded to the body member,the face member includes a rearward extending portion that extends from an outer edge of the face portion toward a back side,the rearward extending portion includes a sole-side rearward extending portion disposed in a sole-side portion of the face member, a toe-side rearward extending portion disposed in a toe-side portion of the face member, and a heel-side rearward extending portion disposed in a heel-side portion of the face member, andthe face member also includes a crown-side edge portion formed by an absence of the rearward extending portion in a crown-side portion of the face member.

2. The golf club head according to claim 1, wherein an edge of the sole-side rearward extending portion, an edge of the toe-side rearward extending portion, an edge of the heel-side rearward extending portion, and the crown-side edge portion lie on a same flat plane.

3. The golf club head according to claim 2, whereinthe golf club head includes a weld bead formed at a boundary between the crown-side edge portion and the body member, andthe body member has a wall thickness at a body-side end point of the weld bead of greater than or equal to 0.7 mm and less than or equal to 1.0 mm.

4. The golf club head according to claim 1, wherein the sole-side rearward extending portion has a length of less than or equal to 20 mm.

5. The golf club head according to claim 1, wherein the golf club head is a fairway wood type head.

6. The golf club head according to claim 1, whereinin an upright cross section that passes through a face center of the striking face,a contour line of the striking face includes the following three points: the face center, a point that is spaced 1 mm upward from the face center, and a point that is spaced 1 mm downward from the face center,an arc of a circle that passes through the three points is defined as an outer surface reference line,a line that is parallel to the outer surface reference line and that passes through an intersection point between an inner surface of the face portion and a straight line that is normal to the striking face at the face center is defined as an inner surface reference line,the crown-side edge portion is positioned on a face side relative to the inner surface reference line, andthe sole-side rearward extending portion extends further backward than the inner surface reference line.

7. The golf club head according to claim 6, whereinthe golf club head includes a weld bead formed at a boundary between the crown-side edge portion and the body member,the golf club head also includes a wall thickness varying portion in which a wall thickness of the golf club head continuously decreases backward from a body-side end point of the weld bead,in the upright cross section,the wall thickness varying portion includes a point where the wall thickness in the wall thickness varying portion is equal to a minimum value of a wall thickness of the sole-side rearward extending portion,a wall thickness of the crown portion on the back side relative to the point is smaller than the wall thickness at the point, anda distance D2 from the point to the inner surface reference line is smaller than a length D1 of the sole-side rearward extending portion.

8. The golf club head according to claim 7, wherein the distance D2 from the point to the inner surface reference line is smaller than half the length D1 of the sole-side rearward extending portion.

9. The golf club head according to claim 7, whereinin the upright cross section, the wall thickness of the golf club head at the body-side end point of the weld bead is smaller than a width LG of the crown-side edge portion.

10. The golf club head according to claim 9, whereinin the upright cross section, the wall thickness of the golf club head at the body-side end point of the weld bead is greater than or equal to 0.7 mm and less than or equal to 1.0 mm.

11. A golf club head comprising: a hollow interior, a face portion that includes a striking face as a front surface, a crown portion, and a sole portion, whereinthe golf club head includes a body member that includes an opening, and a face member that includes the face portion, that covers the opening, and that is welded to the body member,the face member includes a rearward extending portion that extends from an outer edge of the face portion toward a back side,the rearward extending portion includes a sole-side rearward extending portion disposed in a sole-side portion of the face member, andthe face member also includes a crown-side edge portion formed by an absence of the rearward extending portion in a crown-side portion of the face member.

12. The golf club head according to claim 11, wherein an edge of the sole-side rearward extending portion and the crown-side edge portion lie on a same flat plane.

13. The golf club head according to claim 12, whereinthe golf club head includes a weld bead formed at a boundary between the crown-side edge portion and the body member, andthe body member has a wall thickness at a body-side end point of the weld bead of greater than or equal to 0.7 mm and less than or equal to 1.0 mm.

14. The golf club head according to claim 11, wherein the sole-side rearward extending portion has a length of less than or equal to 20 mm.

15. The golf club head according to claim 11, wherein the golf club head is a fairway wood type head.

16. The golf club head according to claim 11, whereinin an upright cross section that passes through a face center of the striking face,a contour line of the striking face includes the following three points: the face center, a point that is spaced 1 mm upward from the face center, and a point that is spaced 1 mm downward from the face center,an arc of a circle that passes through the three points is defined as an outer surface reference line,a line that is parallel to the outer surface reference line and that passes through an intersection point between an inner surface of the face portion and a straight line that is normal to the striking face at the face center is defined as an inner surface reference line,the crown-side edge portion is positioned on a face side relative to the inner surface reference line, andthe sole-side rearward extending portion extends further backward than the inner surface reference line.

17. The golf club head according to claim 16, whereinthe golf club head includes a weld bead formed at a boundary between the crown-side edge portion and the body member,the golf club head also includes a wall thickness varying portion in which a wall thickness of the golf club head continuously decreases backward from a body-side end point of the weld bead,in the upright cross section,the wall thickness varying portion includes a point where the wall thickness in the wall thickness varying portion is equal to a minimum value of a wall thickness of the sole-side rearward extending portion,a wall thickness of the crown portion on the back side relative to the point is smaller than the wall thickness at the point, anda distance D2 from the point to the inner surface reference line is smaller than a length D1 of the sole-side rearward extending portion.

18. The golf club head according to claim 17, wherein the distance D2 from the point to the inner surface reference line is smaller than half the length D1 of the sole-side rearward extending portion.

19. The golf club head according to claim 17, whereinin the upright cross section, the wall thickness of the golf club head at the body-side end point of the weld bead is smaller than a width LG of the crown-side edge portion.

20. The golf club head according to claim 19, whereinin the upright cross section, the wall thickness of the golf club head at the body-side end point of the weld bead is greater than or equal to 0.7 mm and less than or equal to 1.0 mm.

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