Golf club head

Abstract

Providing a golf club head with improved performance through a new face structure. [Solution] A hollow golf club head 100 having a face portion 104. This golf club head 100 is formed by welding a body member b1 having an opening 114 and a face member f1 having a face portion 104 and closing the opening 114. The face member f1 has a rearward extension portion E1 extending from the outer edge of the face portion toward the back. The rearward extension portion E1 has a sole-side rearward extension portion Es provided on the sole side of the face member f1, a toe-side rearward extension portion Et provided on the toe side of the face member f1, and a heel-side rearward extension portion Eh provided on the heel side of the face member f1. On the crown side of the face member f1, there is a crown-side edge portion G1 formed by not providing the rearward extension portion E1.

Description

Technical Field

[0001] The present disclosure relates to a golf club head.

Background Art

[0002] A golf club head having a cup face as a face member is known. Japanese Patent Application Laid-Open No. 2016-26557 discloses a golf club head having a cup face including a rising portion extending from a peripheral edge of a face portion to a back side of the face portion and a head body. This cup face can be made of a material and a manufacturing method different from those of the head body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] It has been found that there is room for improvement in conventional cup faces. One object of the present invention is to provide a golf club head whose performance can be improved by a face member having a new structure.

Means for Solving the Problems

[0005] In one embodiment, the golf club head has a face portion with the striking face facing forward, a crown portion, and a sole portion. The golf club head is hollow. The golf club head is formed by welding a body member having an opening to a face member having the face portion and closing the opening. The face member has a rearward extension portion that extends from the outer edge of the face portion toward the back. The rearward extension portion has a sole-side rearward extension portion provided on the sole side of the face member, a toe-side rearward extension portion provided on the toe side of the face member, and a heel-side rearward extension portion provided on the heel side of the face member. The crown side of the face member is provided with a crown-side edge portion formed by not providing the rearward extension portion. [Effects of the Invention]

[0006] In one respect, a golf club head with a new face structure can be provided that offers improved performance. [Brief explanation of the drawing]

[0007] [Figure 1] Figures 1(a) and 1(b) are front views of a golf club head according to one embodiment. [Figure 2] Figure 2 is a perspective view of the body components that make up the golf club head described above. [Figure 3] Figure 3 is a perspective view of the face component that makes up the golf club head described above. [Figure 4] Figure 4 is a cross-sectional view along line AA in Figure 1(a). [Figure 5] Figure 5 is a cross-sectional view along line BB in Figure 1(a). [Figure 6] Figure 6 is a cross-sectional view along the CC line in Figure 1(a). [Figure 7] Figure 7 is a cross-sectional view along the DD line in Figure 1(a). [Figure 8] Figure 8 is an enlarged view of the same front view as Figure 1(a). [Figure 9]FIG. 9 is an enlarged view of the same cross-sectional view as FIG. 4. [Figure 10] FIG. 10 is a partially enlarged view of FIG. 4. [Figure 11] FIG. 11 is a partially enlarged view of FIG. 5. [Figure 12] FIG. 12 is a partially enlarged view of FIG. 10. [Figure 13] FIG. 13 is a conceptual diagram for explaining the reference state.

BEST MODE FOR CARRYING OUT THE INVENTION

[0008] Hereinafter, the present disclosure will be described in detail based on preferred embodiments while referring to the drawings as appropriate.

[0009] In this specification, a reference state, a reference vertical plane, a toe-heel direction, a face-back direction, an up-down direction, a face center, a radial cross-section, a longitudinal cross-section, a transverse cross-section, a vertical cross-section, and a vertical cross-section line are defined.

[0010] A state where the head is placed on the ground plane HP at a predetermined lie angle is defined as the reference state. As shown in FIG. 13, in this reference state, the shaft axis Z is included in a plane VP perpendicular to the ground plane HP. The shaft axis Z is the center line of the shaft. Usually, the shaft axis Z is the center line of the hosel hole. The plane VP is defined as the reference vertical plane. The predetermined lie angle is, for example, published in a product catalog.

[0011] In this reference state, the face angle is set to 0 degrees. That is, in a plan view seen from above, the tangent line at the face center of the striking face is parallel to the toe-heel direction. The definitions of the face center and the toe-heel direction are as described below.

[0012] The toe-heel direction is the direction of the intersection line NL of the reference vertical plane VP and the ground plane HP (see FIG. 13).

[0013] The face-back direction is perpendicular to the toe-heel direction and parallel to the ground plane HP. The face side is also referred to as the front. The back side is also referred to as the rear.

[0014] The up-down direction is perpendicular to the toe-heel direction and perpendicular to the face-back direction. In other words, the up-down direction is perpendicular to the ground plane HP.

[0015] The face center is determined as follows. First, in the up-down direction and the toe-heel direction, an arbitrary point Pr near the approximate center of the striking face is selected. Next, a plane is determined that passes through this point Pr, extends along the normal direction of the striking face at this point Pr, and is parallel to the toe-heel direction. An intersection line between this plane and the striking face is drawn, and the midpoint Pa is determined. Next, a plane is determined that passes through this midpoint Pa, extends along the normal direction of the striking face at this point Pa, and is parallel to the up-down direction. An intersection line between this plane and the striking face is drawn, and the midpoint Py is determined. Next, a plane is determined that passes through this midpoint Py, extends along the normal direction of the striking face at this point Py, and is parallel to the toe-heel direction. An intersection line between this plane and the striking face is drawn, and the midpoint Px is newly determined. Next, a plane is determined that passes through this new midpoint Px, extends along the normal direction of the striking face at this point Px, and is parallel to the up-down direction. An intersection line between this plane and the striking face is drawn, and the midpoint Py is newly determined. This process is repeated, and Px and Py are sequentially determined. During the repetition of this process, the position Py (the last position Py) when the distance between the new midpoint Py and the immediately preceding midpoint Py first becomes 0.5 mm or less is the face center.

[0016] Note that it may be difficult to determine the face center according to the above definition. In all descriptions of this specification, the face center can be replaced with the sweet spot. The sweet spot is the intersection point between the straight line passing through the center of gravity of the head and perpendicular to the striking face and the striking face.

[0017] A radial section is a cross-section defined by a plane that includes the normal to the striking face at the face center. Many such planes exist, and therefore many radial sections exist.

[0018] A longitudinal section is one of the radial sections, and is perpendicular to the ground plane HP. A transverse section is one of the radial sections, and is perpendicular to the longitudinal section.

[0019] A vertical section is a section that is perpendicular to the ground plane (HP) and parallel to the face-back direction. The vertical section is determined at each position in the toe-heel direction. The vertical section line is the section line of the outer surface of the head in the vertical section.

[0020] Figures 1(a) and 1(b) are front views of a golf club head 100 according to one embodiment, Figure 2 is a perspective view of the body member b1 of the head 100, and Figure 3 is a perspective view of the face member f1 of the head 100. Figure 3 is a perspective view of the face member f1 as seen from the back side of the face portion 104. Figure 4 is a cross-sectional view along line AA in Figure 1(a), Figure 5 is a cross-sectional view along line BB in Figure 1(a), Figure 6 is a cross-sectional view along line CC in Figure 1(a), and Figure 7 is a cross-sectional view along line DD in Figure 1(a).

[0021] Referring to Figure 1(a), Figure 4 (AA section) is a cross-section along plane PL1 containing the normal N1 of the striking face 104a at face center C1, Figure 5 (BB section) is a cross-section along plane PL2 containing the normal N1, Figure 6 (CC section) is a cross-section along plane PL3 containing the normal N1, and Figure 7 (DD section) is a cross-section along plane PL4 containing the normal N1. Figures 4, 5, 6, and 7 are the radial sections described above. Of these, Figure 4 is the longitudinal section described above, and Figure 5 is the cross-section described above.

[0022] The head 100 has a face portion 104, a crown portion 106, a sole portion 108, and a hosel portion 110. The face portion 104 has a striking face 104a and an inner face surface 104b. The striking face 104a is the outer surface (front) of the face portion 104. The inner face surface 104b is the inner surface (rear) of the face portion 104. The crown portion 106 has a crown outer surface 106a and a crown inner surface 106b. The sole portion 108 has a sole outer surface 108a and a sole inner surface 108b.

[0023] As shown in Figure 1(b), the striking face 104a has an outer edge k1. The outer edge k1 is the contour line of the striking face 104a. The outer edge k1 is the boundary line between the striking face 104a and other parts. The outer edge k1 of the striking face 104a can be defined as follows: In each of the radial sections, a point is determined where the radius of curvature of the cross-sectional line of the outer surface of the head first becomes 200 mm when moving from the face center C1 side toward the outside of the striking face 104a. The set of these points can be considered as the outer edge k1 of the striking face 104a.

[0024] The hosel portion 110 has a protruding portion 110a that is exposed to the outside and protrudes from the outer surface 106a of the crown, and an internally extending portion 110b located inside the head 100. The hosel portion 110 also has a hosel hole 112. The hosel hole 112 opens at the upper end of the protruding portion 110a and extends continuously from the protruding portion 110a to the internally extending portion 110b. The head 100 may also have a skirt portion (side portion) extending between the crown portion 106 and the sole portion 108. The striking face is also simply referred to as the face.

[0025] As shown in Figures 4 to 7, the head 100 has a hollow section 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. The head 100 may be a hybrid-type head. The head 100 may be a driver head. From the viewpoint of improving rebound performance when hitting a ball placed directly on the ground (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.

[0026] From a component standpoint, the head 100 has a face member f1 and a body member b1. The face member f1 is welded to the body member b1. As shown in Figure 2, the body member b1 has an opening 114 at its front. The opening 114 is closed by the face member f1. The body member b1 has the entire hosel portion 110. The body member b1 has the entire crown portion 106. The body member b1 has a portion of the sole portion 108 (excluding the front portion). The front portion of the sole portion 108 is provided on the face member f1.

[0027] As shown in Figure 2, the body member b1 has a joint surface 116. The joint surface 116 is the front end surface of the body member b1. At the joint surface 116, the body member b1 is joined to the face member f1.

[0028] As shown in Figure 3, the face member f1 has a joint surface 118. The joint surface 118 is the rear end surface of the rearward-extending portion E1 (described later). The joint surface 118 is joined to the joint surface 116 of the body member b1.

[0029] A boundary k2 exists on the outer surface of the head 100 between the body member b1 and the face member f1 (see Figures 1(a) and 1(b)). After polishing following welding, the outer surface of the head 100 becomes flush at boundary k2, forming a smooth, continuous curved surface. In the finished head 100, boundary k2 is not visible.

[0030] The face member f1 as a whole has a cup shape with the face portion 104 as its base. The face member f1 includes the entire face portion 104. The face member f1 includes the entire striking face 104a. The face member f1 has the face portion 104 and a rear extension portion E1 that extends from the outer edge of the face portion 104 toward the back. However, the face member f1 does not have a rear extension portion E1 on its crown side. Therefore, the face member f1 differs from a conventional cup face. As shown in Figure 3, the rear extension portion E1 has a sole-side rear extension portion Es provided on the sole side of the face member f1, a toe-side rear extension portion Et provided on the toe side of the face member f1, and a heel-side rear extension portion Eh provided on the heel side of the face member f1.

[0031] As shown in Figure 1(b), the outer edge k1 of the striking face 104a has a point Qt on its upper toe side where the radius of curvature is minimal. If the portion with the minimal radius of curvature has width, the midpoint of the path length of the outer edge k1 in that portion is Qt. If there is a point that forms an angle and has a radius of curvature of zero, the vertex of that angle is Qt. From the radial cross-section, the plane PL5 passing through point Qt is determined. If the outer edge k1 is interrupted on the upper toe side, the midpoint of the shortest line connecting the interrupted ends may be considered as point Qt.

[0032] Similarly, the outer edge k1 of the striking face 104a has a point Qh on its upper heel side where the radius of curvature is minimal. If the portion with the minimal radius of curvature has width, the midpoint of the path length of the outer edge k1 in that portion is Qh. If there is a point that forms an angle and has a radius of curvature of zero, the vertex of that angle is Qh. From the aforementioned radial cross-section, the plane PL6 passing through point Qh is determined. Note that if the outer edge k1 is interrupted on the upper heel side, the midpoint of the shortest line connecting the interrupted ends may be considered as point Qh.

[0033] The area above plane PL5 and above plane PL6 may be considered the crown area (CR). The area below plane PL5 and below plane PL6 may be considered the sole area (SL). The area above plane PL5 and below plane PL6 may be considered the heel area (HL). The area below plane PL5 and above plane PL6 may be considered the toe area (TE).

[0034] The posterior extension E1 located in the sole region SL may be referred to as the sole-side posterior extension Es. The posterior extension E1 located in the heel region HL may be referred to as the heel-side posterior extension Eh. The posterior extension E1 located in the toe region TE may be referred to as the toe-side posterior extension Et.

[0035] As shown in Figure 1(b), the toe-heel direction range U1 from point Qt to point Qh is determined. Range U1 is the range that is heel-side from point Qt and toe-side from point Qh. In range U1, there is no rearward extension E1 in the crown region CR. That is, in the range U1 that is heel-side from point Qt and toe-side from point Qh, there is no rearward extension E1. There may be a rearward extension E1 in the crown region CR on the toe side of point Qt, and there may be a rearward extension E1 in the crown region CR on the heel side of point Qh.

[0036] The crown side of the face member f1 is provided with a crown-side edge portion G1, which is formed by not providing a rearward-extending portion E1 (see Figure 3). The crown-side edge portion G1 is provided in the toe-heel direction range U1. The crown-side edge portion G1 is provided near the boundary between the crown portion 106 and the face portion 104.

[0037] As shown in Figure 3, the face member f1 has a notch 119 on the upper side of the heel. The notch 119 is located where it connects to the hosel portion 110. The rearward extension portion E1 does not exist at the location where the notch 119 is located. When the rearward extension portion E1 of the face member f1 is welded to the body member b1, the notch 119 forms a gap between it and the body member b1. By looking into the inner surface of the head through this gap, the state of the weld between the rearward extension portion E1 and the body member b1 can be confirmed. Subsequently, the gap caused by the notch 119 is filled with a weld bead.

[0038] The material of the face member f1 is metal. Examples of this metal include stainless steel, maraging steel, titanium alloy, aluminum alloy, and magnesium alloy. A portion of the face member f1 may be made of a non-metallic material. For example, a portion of the face member f1 may be made of carbon fiber reinforced resin. However, at least the portion 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 can be welded to the body member b1. From the viewpoint of strength, titanium alloy and maraging steel are preferred materials for the face member f1. The method of manufacturing the face member f1 is not limited. From the viewpoint of strength, the face member f1 may be manufactured by press working a sheet metal. Rolled material may be used as this sheet metal. Rolled material has few defects and excellent strength. Furthermore, rolled material has high thickness accuracy. By using rolled material, the thickness accuracy of the face portion 104 is improved. The face member f1 may be manufactured, for example, by forging. The face member f1 may be manufactured by casting. As described later, the face member f1 of this embodiment does not have a rearward extension E1 on the crown side. For this reason, the face member f1 can be easily formed by pressing or forging compared to a normal cup face. In this embodiment, the face member f1 is manufactured by pressing a rolled material. More specifically, the manufacturing process of the face member f1 may include a first step of processing the thickness of a sheet material (rolled material) by CNC machining, a second step of pressing the sheet material after the first step, and a third step of shaping the peripheral edge using the material after the second step by CNC machining. In the second step, a curved surface (bulge, roll) is given to the face portion and a rearward extension E1 is formed. A third step of shaping the rearward extension E1 may be performed after the pressing step. This third shaping step involves adjusting the length of the rearward extension E1 and / or shaping the outer surface of the rearward extension E1. Laser cutting may be used to adjust the length of the rearward extension E1. CNC machining may be used to shape the outer surface of the rearward extension E1. When shaping the outer surface of the rearward extension E1 in the third step, the wall thickness may be set in the first step, taking into account the amount of material removed from the outer surface in the third step.CNC stands for Computerized Numerical Control.

[0039] The material of the body member b1 is metal. Examples of this metal include stainless steel, maraging steel, titanium alloy, aluminum alloy, and magnesium alloy. A portion of the body member b1 may be made of a non-metallic material. For example, a portion of the body member b1 may be made of carbon fiber reinforced resin. The body member b1 and the face member f1 are welded together, and the joint surface 116 of the body member b1 is made of metal. The body member b1 may be integrally molded as a whole. The body member b1 may be formed by joining multiple members. For example, the body member b1 may be formed by joining a metal member and a carbon fiber reinforced plastic member. In this embodiment, the entire body member b1 is made of metal. The method of manufacturing the body member b1 is not limited. In this embodiment, the body member b1 is manufactured by casting (lost-wax precision casting).

[0040] The head 100 has an internal weight portion 120. The body member b1 has an internal weight portion 120. The internal weight portion 120 is located inside the sole portion 108. The internal weight portion 120 is located on the inner surface 108b of the sole portion 108. The internal weight portion 120 is a portion that protrudes from the inner surface 108b of the sole.

[0041] The internal weight section 120 is integral with the sole section 108. The internal weight section 120 is integrally molded with the sole section 108. The internal weight section 120 is integral with the body member b1. The entire body member b1, including the internal weight section 120, is integrally molded. The method of molding the body member b1 is casting. The body member b1 is molded by lost-wax precision casting. The internal weight section 120 may be a separate component from the sole section 108. The internal weight section 120 may be molded separately from the body member b1. The internal weight section 120 may be molded independently and fixed to the sole section 108. Examples of this fixing method include welding, press-fitting, screwing, and bonding.

[0042] The internal weight section 120 is located on the back side of the face section 104. The internal weight section 120 is spaced apart from the face section 104. The internal weight section 120 is located on the back side of the planar PL (described later).

[0043] The internal weight section 120 (the central section 120M described later) has a base 122 and a projection 124 that protrudes from the base 122 toward the face. The base 122 protrudes upward from the inner surface 108b of the sole section 108. The base 122 is integral with the sole section 108. The projection 124 extends upward as it approaches the face.

[0044] The protrusion 124 is located on the face side of the head's center of gravity. The entire protrusion 124 is located on the face side of the head's center of gravity.

[0045] As shown in Figure 4, a recess r1 is formed between the internal weight portion 120 and the sole portion 108, opening towards the face. In each vertical cross-section, the point tx furthest back on the cross-sectional line forming the recess r1 is determined. Furthermore, in the vertical cross-section, a straight line X1 passing through this point tx and extending in the vertical direction is determined. Furthermore, the intersection point ty between this straight line X1 and the upper surface of the internal weight portion 120 is determined. The line segment connecting point tx and point ty can be considered the boundary between the base portion 122 and the protruding portion 124.

[0046] The projection 124 has an upper surface 124a and a lower surface 124b. Furthermore, the projection 124 has a front end surface 124c. The front end surface 124c is the face-side end surface of the projection 124. The front end surface 124c extends between the front edge of the upper surface 124a and the front edge of the lower surface 124b. The front end surface 124c is optional. For example, if the tip of the projection 124 is pointed, the front end surface 124c is not formed.

[0047] The upper surface 124a is inclined so that it becomes higher as it approaches the face portion 104. The lower surface 124b is inclined so that it becomes higher as it approaches the face portion 104. 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.

[0048] The base portion 122 has an upper surface 122a. The upper surface 122a is inclined to be upward as it approaches the face portion 104. The upper surface 122a may be a flat surface or a curved surface. In this embodiment, the upper surface 122a is a single flat surface. The upper surface 122a terminates on the back side by reaching the inner surface 108b of the sole portion 108. The upper surface 122a is inclined to be upward as it approaches the projection portion 124. The entire upper surface of the internal weight portion 120, including the upper surface 122a and the upper surface 124a, is inclined to be upward as it approaches the face portion 104. In the internal weight portion 120, the upper surface 122a and the upper surface 124a are flush. 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.

[0049] Referring to Figure 2, the internal weight section 120 has a toe-side portion 120T, a heel-side portion 120H, and a central portion 120M. The toe-side portion 120T is located 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 located 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 located between the toe-side portion 120T and the heel-side portion 120H. The entire toe-side portion 120T is located on the toe side of the face center C1. The entire heel-side portion 120H is located on the heel side of the face center C1. The toe-heel range of the central portion 120M includes the toe-heel position of the face center C1.

[0050] The central portion 120M has the base portion 122 and the protruding portion 124. As shown in Figure 2, the toe portion 120T does not have the protruding portion 124. In the toe portion 120T, there is no portion that floats above the inner surface 108b of the sole. The entire toe portion 120T protrudes upward from the inner surface 108b of the sole. In the toe portion 120T, the recess r1 (see Figure 4) is filled in. Also, the upper surface of the toe portion 120T is located above the upper surface of the central portion 120M. In the internal weight portion 120, the weight distribution to the toe portion 120T is large.

[0051] As shown in Figure 2, the heel portion 120H does not have a protrusion 124. No portion of the heel portion 120H is formed that is raised from the inner surface 108b of the sole. The entire heel portion 120H protrudes upward from the inner surface 108b of the sole. The recess r1 (see Figure 4) is filled in the heel portion 120H. Also, the upper surface of the heel portion 120H is located above the upper surface of the central portion 120M. In the internal weight section 120, the weight distribution to the heel portion 120H is large. Overall, the internal weight section 120 achieves weight distribution to the toe side and heel side. This weight distribution contributes to increasing the moment of inertia of the head.

[0052] As shown in Figure 2, the internal extension 110b is connected to the internal weight portion 120 (heel-side portion 120H). This configuration allows the internal weight portion 120 to be positioned closer to the heel, thereby reducing the center of gravity distance. Reducing the center of gravity distance promotes face rotation, resulting in a head that is easier to grip.

[0053] "Good grip" means that the 104a face is less likely to open at impact. With a head that grips well, the 104a face tends to be square or slightly closed at impact. With a head that grips well, the head's energy is efficiently transferred to the ball, which can increase distance. The center of gravity distance is the distance between the shaft axis and the head's center of gravity.

[0054] The back edge 126 of the internal weight section 120 (see Figure 4) is located behind the head's center of gravity. On the other hand, as mentioned above, the center of gravity of the protrusion 124 is located behind the head's center of gravity. The center of gravity of the internal weight section 120 is located behind the head's center of gravity. The center of gravity of the base 122 is located behind the head's center of gravity. As shown in Figure 4, in the base 122, the upper surface 122a has a sloping portion that becomes lower towards the back, extending behind the head's center of gravity. Therefore, more weight can be distributed to the underside of the head 100. On the other hand, by positioning the center of gravity of the protrusion 124 behind the head's center of gravity, the depth of the center of gravity is reduced. These configurations allow the sweet spot to be lowered. The effect of lowering the sweet spot is further enhanced by positioning the center of gravity of the internal weight section 120 behind the head's center of gravity. The effect of lowering the sweet spot is further enhanced by positioning the center of gravity of the base 122 closer to the face than the head's center of gravity. The center of gravity depth is the face-to-back distance between the shaft axis Z and the head's center of gravity.

[0055] Figure 8 is an enlarged view of the same front view as Figure 1(a). Figure 9 is an enlarged view of the same cross-sectional view as Figure 4.

[0056] The striking face 104a has a bulge and a roll. The bulge is a curve in the lateral direction. The bulge is a curve in a cross section parallel to the ground plane HP (see Figure 5). The roll is a curve in the longitudinal direction. The roll is a curve in a vertical cross section (see Figure 4).

[0057] The head 100 has a radius of curvature R at the boundary between the striking face 104a and the crown outer surface 106a (see Figures 4 and 8). The radius of curvature R is measured along the vertical section line. The radius of curvature R is determined at each position in the toe-heel direction. As shown in Figure 8, the radius of curvature R at a position 15 mm toe-side from the face center C1 is the radius of curvature Rt. The radius of curvature R at the face center C1 is the radius of curvature Rc. See also Figure 4 for the radius of curvature Rc. The radius of curvature R at a position 15 mm heel-side from the face center C1 is the radius of curvature Rh. For ease of understanding, in this specification, "R", "Rt", "Rc", "Rh", etc. are symbols that identify the type of radius of curvature, and are also used as reference numerals in drawings. The unit of these radii of curvature is mm.

[0058] The head 100 has a radius of curvature S at the boundary between the striking face 104a and the outer sole surface 108a (see Figures 4 and 8). The radius of curvature S is measured along the vertical section line. The radius of curvature S is measured at various positions in the toe-heel direction. As shown in Figure 8, the radius of curvature S at a position 15 mm toe-side from the face center C1 is the radius of curvature St. The radius of curvature S at the face center C1 is the radius of curvature Sc. See also Figure 4 for the radius of curvature Sc. The radius of curvature S at a position 15 mm heel-side from the face center C1 is the radius of curvature Sh. For ease of understanding, in this specification, "S", "St", "Sc", "Sh", etc. are symbols that identify the type of radius of curvature, and are also used as reference numerals in drawings. The unit of these radii of curvature is mm.

[0059] The striking face 104a has a face height F. The face height F is measured in a vertical section. The face height F is measured at various positions in the toe-heel direction. The face height F at a position 15 mm toe-side from the face center C1 is the face height Ft. The face height F at the position of the face center C1 is the face height Fc. The face height F at a position 15 mm heel-side from the face center C1 is the face height Fh. For ease of understanding, in this specification, "F", "Ft", "Fc", "Fh", etc., are symbols that identify the type of radius of curvature and are also used as reference numerals in drawings. The unit of these face heights is mm.

[0060] As shown in Figure 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 at various positions in the toe-heel direction. The head thickness T at a position 15 mm toe-side from the face center C1 is the head thickness Tt. The head thickness T at the position of the face center C1 is the head thickness Tc (see Figure 9). The head thickness T at a position 15 mm heel-side from the face center C1 is the head thickness Th. For ease of understanding, in this specification, "T", "Tt", "Tc", "Th", etc. are symbols that specify the type of radius of curvature, and are also used as reference numerals in drawings. "Tt" and "Th" are omitted from the illustration. The unit of these head thicknesses is mm.

[0061] The area from 15mm toe-side of face center C1 to 15mm heel-side of face center C1 has a high probability of being struck. This area is referred to as the primary striking area.

[0062] The definition of the radius of curvature R may be as follows: In a vertical section line, the point with the smallest radius of curvature between the point constituting the outer edge k1 on the crown side (outer edge point) and the outer surface 106a of the crown is determined as the crown specific point. If the portion with the smallest radius of curvature is a range rather than a point, the midpoint of that range is determined as the crown specific point. This midpoint is determined based on the distance along the vertical section line. A crown auxiliary point is determined on the crown side of this crown specific point. The crown auxiliary point is determined such that the crown specific point is the midpoint between the crown auxiliary point and the outer edge point. This midpoint is determined based on the distance. That is, the distance between the crown specific point and the crown auxiliary point is equal to the distance between the outer edge point and the crown specific point. The radius of curvature R may be defined as the radius of the circle passing through the three points: the outer edge point, the crown specific point, and the crown auxiliary point.

[0063] The definition of the radius of curvature S may be as follows: In a vertical section line, the point with the smallest radius of curvature between the point constituting the outer edge k1 on the sole side (outer edge point) and the outer surface 108a of the sole is determined as the sole specific point. If the portion with the smallest radius of curvature is a range rather than a point, the midpoint of that range is determined as the sole specific point. This midpoint is determined based on the distance along the vertical section line. A sole auxiliary point is determined on the sole side of this sole specific point. The sole auxiliary point is determined such that the sole specific point is the midpoint between the sole auxiliary point and the outer edge point. This midpoint is determined based on the distance. That is, the distance between the sole specific point and the sole auxiliary point is equal to the distance between the outer edge point and the sole specific point. The radius of curvature S may be defined as the radius of the circle passing through the three points: the outer edge point, the sole specific point, and the sole auxiliary point.

[0064] The face height F can be defined as follows: The distance between the outer edge point on the crown side and the outer edge point on the sole side (the straight-line distance between the two points on the vertical cross-section) can be defined as the face height F (see Figure 9).

[0065] The definition of head thickness T can be as follows: As shown in Figure 9, a horizontal line L1 tangent to the upper side of the vertical section line and a horizontal line L2 tangent to the lower side of the vertical section line are determined. The distance between lines L1 and L2 can be defined as the head thickness T. Lines L1 and L2 are parallel to the ground plane HP. The direction of measurement for head thickness T is vertical. Therefore, head thickness T corresponds to the maximum thickness of the head at each position in the toe-heel direction. The face-back position of the highest point of the head Jm tangent to line L1 is changing. In the main hitting area, the face-back position of the highest point of the head Jm moves towards the back as you move towards the toe.

[0066] In head 100, the radius of curvature R on the crown side is not constant. The radius of curvature R changes depending on the position in the toe-heel direction. This change in the radius of curvature R is continuous. Head 100 satisfies the following relationship (a). Furthermore, head 100 satisfies the following relationship (a1). (a) Rt > Rc ≥ Rh (a1) Rt > Rc > Rh

[0067] In head 100, the radius of curvature S on the sole side is not constant. The radius of curvature S changes depending on the toe-heel position. This change in the radius of curvature S is continuous. Head 100 does not satisfy the following relationship (b). Head 100 does not satisfy the following relationship (b1). Head 100 does not satisfy the following relationship (b2). Head 100 satisfies the following relationship (b3). In head 100, the radius of curvature St is smaller than the radius of curvature Sc. In head 100, the radius of curvature Sc is smaller than the radius of curvature Sh. Relationship (b3) can suppress the radius of curvature St. (b) St > Sc ≥ Sh (b1) St>Sc>Sh (b2) St <sc>Sh (b3) St <Sc<Sh

[0068] With respect to the head thickness T, head 100 does not satisfy the following relationship (c). Head 100 satisfies the following relationship (c1). In head 100, the head thickness Tt is smaller than the head thickness Tc. In head 100, the head thickness Tc is larger than the head thickness Th. (c)Tt>Tc>Th (c1)Tt <tc>Th

[0069] For Head 100 (fairway wood type head), the difference (Tt-Th) may be 5.0 mm or less, further 4.5 mm or less, and further 4.0 mm or less. The difference (Tt-Th) may be 1.0 mm or more, further 1.5 mm or more, and further 2.0 mm or more.

[0070] With respect to the face height F, head 100 satisfies the following relationship (d): (d)Ft <fc>Fh

[0071] In head 100, the face height Ft is suppressed and close to the face height Fh. The face height Ft is smaller than the face height Fc. The face height Ft is larger than the face height Fh. However, the face height Ft is approximately equal to the face height Fh. The face height Ft may be smaller than the face height Fh. The absolute value of the difference (Ft-Fh) may be 1.5 mm or less, further 1.0 mm or less, and further 0.5 mm or less.

[0072] Regarding the ratio of face height F to head thickness T, head 100 satisfies the following relationship (e). (e)Ft / Tt < Fh / Th

[0073] Furthermore, head 100 satisfies the following relationships (f) and (f1). (f)Ft / Tt < Fc / Tc ≤ Fh / Th (f1)Ft / Tt < Fc / Tc < Fh / Th

[0074] In head 100, the radius of curvature St is smaller than the radius of curvature Rt. In head 100, the radius of curvature Sc is smaller than the radius of curvature Rc. In head 100, the radius of curvature Sh is smaller than the radius of curvature Rh.

[0075] In head 100, which is an example of a fairway wood type head, the dimensions may be as follows: • Radius of curvature Rt on the crown side: 12.33 mm • Radius of curvature Rc on the crown side: 10.11 mm • Radius of curvature Rh on the crown side: 7.72 mm • Radius of curvature on the sole side St: 3.25mm • Radius of curvature (Sc) on the sole side: 3.47mm • Radius of curvature on the sole side: 3.63mm Face height Ft: 22.81mm Face height Fc: 24.46mm Face height Fh: 22.72mm • Head thickness Tt: 36.37mm • Head thickness Tc: 36.39mm • Head thickness Th: 33.45mm

[0076] By satisfying at least one of the following relationships (a) and (b), and increasing at least one of the radius of curvature Rt and St on the toe side, the face height Ft can be suppressed, and the following relationship (e) may hold. In this case, when hitting on the toe side, the boundary area with a large radius of curvature (the part with radius of curvature Rt and / or radius of curvature St) flexes, and because the face height Ft is small, the load on the face is reduced. Therefore, the durability of the head is improved (toe durability improvement effect). When the face height Ft is suppressed, the flexing of the face becomes smaller, which may cause a decrease in rebound performance. However, because the boundary area with a large radius of curvature Rt and / or St flexes, the overall amount of flexing on the toe side can be maintained. Therefore, rebound performance can be maintained (toe rebound maintenance effect). On the other hand, on the heel side, the face height Fh is basically small due to the structure of the head, which is advantageous in terms of durability. By reducing the radius of curvature Rh and / or radius of curvature Sh, the face height Fh can be secured. By securing the face height Fh, the flex of the face portion 104 is ensured on the heel side, thereby improving rebound performance (heel rebound improvement effect). In addition, by maintaining the face height Fh on the heel side, the visible hitting face does not become narrower, providing a sense of security at address. From these viewpoints, it is more preferable to satisfy at least one of the following (a1) and (b1). (a) Rt > Rc ≥ Rh (b) St > Sc ≥ Sh (a1) Rt > Rc > Rh (b1) St>Sc>Sh (e)Ft / Tt < Fh / Th

[0077] The above relationship in the main striking area enhances the effects described above in actual striking.

[0078] This embodiment satisfies the above relationship (a) or (a1), and relationship (e) is established. Therefore, when striking on the toe side, the crown-side boundary portion having a large radius of curvature Rt flexes, and the face height Ft on the toe side is suppressed. Thus, the load on the face portion on the toe side is reduced, and the durability of the head is improved (toe durability improvement effect). When the face height Ft is suppressed, the flexing of the face portion becomes smaller and the rebound performance may decrease, but since the portion with radius of curvature Rt flexes, the overall amount of flexing can be maintained. Thus, the rebound performance on the toe side can be maintained (toe rebound maintenance effect). On the other hand, on the heel side, the face height Fh is basically small, which is advantageous in terms of durability. By reducing the radius of curvature Rh, the face height Fh can be secured. By securing the face height Fh, the flexing of the face portion on the heel side can be secured, and the rebound performance can be improved (heel rebound improvement effect). Due to these effects, the rebound performance and durability of the entire face portion can be improved. Furthermore, by maintaining the face height Fh on the heel side, the visible impact face does not become smaller, providing a sense of confidence at address.

[0079] This embodiment satisfies the following relationship (f). Furthermore, this embodiment satisfies the following relationship (f1). Therefore, the effect based on the above relationship (e) is further enhanced. (f)Ft / Tt < Fc / Tc ≤ Fh / Th (f1)Ft / Tt < Fc / Tc < Fh / Th

[0080] This embodiment does not satisfy relationships (b) and (b1). The head of another embodiment may satisfy relationship (b) instead of relationship (a). Also, the head of another embodiment may satisfy relationship (b1) instead of relationship (a1). The head of another embodiment may satisfy relationships (a) and (b). Also, the head of another embodiment may satisfy relationships (a1) and (b1). If the face height Ft is too small, the hitting face may appear narrow, which can reduce confidence at address. From this viewpoint, if relationship (a) is satisfied, it is preferable that relationship (b) is not satisfied, and it is more preferable that relationship (b2) or (b3) is satisfied. If relationship (a1) is satisfied, it is preferable that relationship (b1) is not satisfied, and it is more preferable that relationship (b2) or (b3) is satisfied.

[0081] When relationships (b) and (b1) are satisfied, the change in the radius of curvature S on the sole side is large, which tends to increase the influence on the shape of the sole surface. The shape of the sole surface affects the ground contact resistance of the head. From the viewpoint of design freedom for the shape of the sole surface, a head that does not satisfy relationships (b) and (b1) is preferable. On the other hand, when relationship (b) or (b1) is satisfied, relationship (e) can be achieved without changing the radius of curvature R. When the radius of curvature R is changed, it tends to affect how the head looks at address. If you want the head to look the same at address as a conventional head, you can satisfy relationship (b) or (b1).

[0082] The distribution of impact points on the clubface is highest in the region from below the heel to above the toe. By satisfying relationship (b) or (b1), it is possible to form the impact face in a region with a high density of impact points.

[0083] The position 15 mm toe-side from the face center C1 is also called the toe reference position. The position of the face center C1 is also called the center position. The position 15 mm heel-side from the face center C1 is also called the heel reference position. The main hitting area is the area from the heel reference position to the toe reference position.

[0084] In the main striking region, the radius of curvature R changes continuously. In this main striking region, the radius of curvature R increases towards the toe. In the main striking region, the radius of curvature S may also change continuously. In this case, in this main striking region, the radius of curvature S may be made to increase towards the toe.

[0085] In the fairway wood type head (this embodiment) and the hybrid type head, the radius of curvature S on the sole side is smaller than the radius of curvature R on the crown side. That is, the radius of curvature St is smaller than the radius of curvature Rt, the radius of curvature Sc is smaller than the radius of curvature Rc, and the radius of curvature Sh is smaller than the radius of curvature Rh. With the fairway wood type head and the hybrid type head, there are many occasions when hitting a ball placed directly on the grass without teeing it up. If the radius of curvature S is large, the vertical distance from the contact surface to the leading edge tends to be large. In this case, when hitting a ball placed directly on the ground (grass, etc.), mis-shots (so-called tops, or thin shots in English) are more likely to occur. In this embodiment, these mis-shots are suppressed.

[0086] From the viewpoint of suppressing the above mis-shots, the following is preferable for fairway wood type heads and hybrid type heads: The radius of curvature St is preferably 7.0 mm or less, more preferably 6.0 mm or less, more preferably 5.0 mm or less, and more preferably 4.0 mm or less. From the viewpoint of suppressing face height Ft, the radius of curvature St is preferably 1.5 mm or more, more preferably 2.0 mm or more, and more preferably 2.5 mm or more.

[0087] From the viewpoint of suppressing the above mis-shots, the following is preferable for fairway wood type heads and hybrid type heads: The radius of curvature Sc is preferably 7.0 mm or less, more preferably 6.0 mm or less, more preferably 5.0 mm or less, and more preferably 4.0 mm or less. From the viewpoint of ground resistance, the radius of curvature Sc is preferably 1.5 mm or more, more preferably 2.0 mm or more, and more preferably 2.5 mm or more.

[0088] From the viewpoint of suppressing the above-mentioned mis-shots and maintaining the face height Fh, the following are preferred for fairway wood type heads and hybrid type heads. The radius of curvature Sh is preferably 7.0 mm or less, more preferably 6.0 mm or less, more preferably 5.0 mm or less, and more preferably 4.0 mm or less. From the viewpoint of ground resistance, the radius of curvature Sh is preferably 1.5 mm or more, more preferably 2.0 mm or more, and more preferably 2.5 mm or more.

[0089] In driver heads, the radius of curvature S can be set larger compared to fairway wood and hybrid heads. Driver heads are used to strike a teed-up ball, making them less prone to the aforementioned mis-shots. Also, driver heads have a relatively large face height F, allowing for greater room to reduce the face height F. From these perspectives, it is desirable to increase the radius of curvature S in driver heads to increase the flex at the boundary on the sole side and improve rebound performance. In driver heads, the radii of curvature St, Sc, and Sh can be 7.5 mm or more, and even 8.0 mm or more, and even 8.5 mm or more. From the perspective of preventing excessively small radius of curvature and face height Ft, in driver heads, the radii of curvature St, Sc, and Sh can be 12.0 mm or less, and even 11.0 mm or less, and even 10.0 mm or less.

[0090] From the viewpoint of suppressing the above mis-shots, Rt / St is preferably 1.5 or higher, more preferably 2.0 or higher, and most preferably 2.5 or higher. Considering the preferred values ​​of the radius of curvature St and face height Ft, Rt / St is preferably 5.0 or lower, more preferably 4.5 or lower, and most preferably 4.0 or lower.

[0091] From the viewpoint of suppressing the above mis-shots, Rc / Sc is preferably 1.5 or higher, more preferably 2.0 or higher, and most preferably 2.5 or higher. Considering the preferred values ​​of radius of curvature Sc and face height Fc, Rc / Sc is preferably 5.0 or lower, more preferably 4.5 or lower, and most preferably 4.0 or lower.

[0092] From the viewpoint of suppressing the above mis-shots, Rh / Sh is preferably 1.0 or higher, more preferably 1.5 or higher, and even more preferably 2.0 or higher. Considering the preferred values ​​of radius of curvature Sh and face height Fh, Rh / Sh is preferably 4.5 or lower, more preferably 4.0 or lower, and even more preferably 3.5 or lower.

[0093] Rt / Rh is the ratio of the radius of curvature Rt on the toe side to the radius of curvature Rh on the heel side. From the viewpoint of improving toe durability, maintaining toe rebound, and improving heel rebound, Rt / Rh is preferably 1.20 or higher, more preferably 1.25 or higher, more preferably 1.30 or higher, more preferably 1.35 or higher, and more preferably 1.40 or higher. If the radius of curvature Rt is too large, the face height Ft will be too small, which may reduce the sense of security at address. From this viewpoint, Rt / Rh is preferably 1.80 or lower, more preferably 1.75 or lower, and more preferably 1.70 or lower.

[0094] When the above relationship (a) or (a1) is satisfied and Rt / Rh is large, it is preferable that St / Sh be small. If Rt / Rh and St / Sh are large, the face height Ft may be too small. If the face height Ft is too small, the sense of security at address may decrease. From this viewpoint, when Rt / Rh is in the above preferred range of 1.20 or more, St / Sh is preferably 1.15 or less, more preferably 1.10 or less, and more preferably 1.05 or less. If the radius of curvature St is too small, the face height Ft increases, and the above effect of improving toe durability may decrease. From this viewpoint, St / Sh is preferably 0.80 or more, more preferably 0.85 or more, and more preferably 0.90 or more.

[0095] Ft / Fh is the ratio of the face height Ft on the toe side to the face height Fh on the heel side. From the viewpoint of improving toe durability, maintaining toe rebound, and improving heel rebound, Ft / Fh is preferably 1.15 or less, more preferably 1.12 or less, more preferably 1.09 or less, and more preferably 1.06 or less. If the radius of curvature Rt or radius of curvature St is too large and the face height Ft is too small, the sense of security at address may decrease. From this viewpoint, Ft / Fh is preferably 0.85 or more, more preferably 0.90 or more, and more preferably 0.95 or more.

[0096] In order to satisfy the above relationship (a) or (a1) and relationship (e), enhance the above-mentioned effects based on these relationships, and conform to the specifications of each head type, the radius of curvature R may be within the following range. In the following description, (x) is a preferred range, (y) is a more preferred range, and (z) is an even more preferred range.

[0097] [Driver head radius of curvature Rt] (x)9.5mm or more and 13.5mm or less (y) 10.0 mm or more and 13.0 mm or less (z)10.5mm or more and 12.5mm or less

[0098] [Driver head radius of curvature Rc] (x)7.5mm or more and 11.5mm or less (y) 8.0 mm to 11.0 mm (z)8.5mm or more and 10.5mm or less

[0099] [Driver head radius of curvature Rh] (x)6.0mm or more and 10.0mm or less (y)6.5mm or more and 9.5mm or less (z)7.0mm or more and 9.0mm or less

[0100] [Rt - radius of curvature of fairway wood head] (x)10.0mm or more and 14.0mm or less (y) 10.5mm or more and 13.5mm or less (z) 11.0mm or more and 13.0mm or less

[0101] [Rc radius of curvature of fairway wood head] (x)8.0mm or more and 12.0mm or less (y)8.5mm or more and 11.5mm or less (z)9.0mm or more and 11.0mm or less

[0102] [Rh - radius of curvature of fairway wood head] (x)6.0mm or more and 10.0mm or less (y)6.5mm or more and 9.5mm or less (z)7.0mm or more and 9.0mm or less

[0103] [Hybrid head radius Rt] (x)7.5mm or more and 11.5mm or less (y) 8.0 mm to 11.0 mm (z)8.5mm or more and 10.5mm or less

[0104] [Hybrid head radius Rc] (x)6.0mm or more and 10.0mm or less (y)6.5mm or more and 9.5mm or less (z)7.0mm or more and 9.0mm or less

[0105] [Hybrid head radius of curvature Rh] (x)4.5mm or more and 8.5mm or less (y) 5.0 mm or more and 8.0 mm or less (z)5.5mm or more and 7.5mm or less

[0106] From the viewpoint of satisfying the above relationships (e), (f), or (f1), enhancing the above effects resulting from these relationships, and conforming to the specifications of each head type, the ratio (F / T) may be within the following range. In the following description, (x) is a preferred range, (y) is a more preferred range, and (z) is an even more preferred range.

[0107] [Driver head Ft / Tt] (x) 0.61 or more and 0.71 or less (y) 0.62 or more and 0.70 or less (z) 0.63 or more and 0.69 or less

[0108] [Driver head Fc / Tc] (x) 0.62 or more and 0.72 or less (y) 0.63 or more and 0.71 or less (z) 0.64 or more and 0.70 or less

[0109] [Driver head Fh / Th] (x) 0.64 or more and 0.74 or less (y) 0.65 or more and 0.73 or less (z) 0.66 or more and 0.72 or less

[0110] [Ft / Tt of fairway wood-type heads] (x)0.58 or more and 0.68 or less (y) 0.59 or more and 0.67 or less (z) 0.60 or more and 0.66 or less

[0111] [Fairway wood type head Fc / Tc] (x) 0.62 or more and 0.72 or less (y) 0.63 or more and 0.71 or less (z) 0.64 or more and 0.70 or less

[0112] [Fh / Th of fairway wood-type heads] (x) 0.63 or more and 0.73 or less (y) 0.64 or more and 0.72 or less (z) 0.65 or more and 0.71 or less

[0113] [Ft / Tt of hybrid head] (x)0.68 or more and 0.78 or less (y) 0.69 or more and 0.77 or less (z)0.70 or more and 0.76 or less

[0114] [Fc / Tc of hybrid heads] (x)0.71 or more and 0.81 or less (y) 0.72 or more and 0.80 or less (z) 0.73 or more and 0.79 or less

[0115] [Fh / Th of hybrid heads] (x) 0.72 or more and 0.82 or less (y) 0.73 or more and 0.81 or less (z) 0.74 or more and 0.80 or less

[0116] The following are typical specifications for a driver head (including mini-drivers that are similar to drivers): (1a) to (1e). (1a) Curved striking face (1b) Hollow structure (1c) 300cm 3 Over 470cm 3 The following volume (1d) Real loft angle between 7 and 13 degrees (1e) The presence of a crown

[0117] Examples of fairway wood-type heads include the 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). The following (2a) to (2e) are typical specifications for fairway wood-type heads. (2a) Curved striking face (2b) Hollow structure (2c) 100cm 3 That's 300cm 3 smaller volume (2d) Real loft angle greater than 13 degrees and less than or equal to 33 degrees (2e) The presence of the crown

[0118] Examples of hybrid heads include the Hybrid 3 (H3), Hybrid 4 (H4), Hybrid 5 (H5), and Hybrid 6 (H6). The following (3a) to (3e) are typical configurations of hybrid heads. (3a) Curved striking face (3b) Hollow structure (3c) 90cm 3 More than 140cm 3 The following volume (3D) Real loft angle between 15 and 33 degrees (3e) The presence of the crown

[0119] Hybrid heads are also called utility heads in Japan. Furthermore, hybrid heads are sometimes distinguished into wood-type and iron-type hybrid heads. Iron-type hybrid heads do not have a crown.

[0120] It has a crown, a loft angle (real loft angle) greater than 13 degrees, and a volume of 300 cm³. 3 Smaller heads may be classified as fairway wood type heads or hybrid type heads. Fairway wood type heads and hybrid type heads can be distinguished by W1 / W2. In Figure 9, the double arrow W1 indicates the face-back width of head 100 at the face center C1. In Figure 8, the double arrow W2 indicates the toe-heel width of head 100. For hybrid type heads, W1 / W2 is less than 0.65. For fairway wood type heads, W1 / W2 is 0.65 or more. They have a crown and a volume of 300 cm³. 3 A head that meets the above criteria can be considered a driver head.

[0121] Figure 10 is a magnified section of Figure 4, and Figure 11 is a magnified section of Figure 5.

[0122] A weld bead wb is formed at the welded joint between the face member f1 and the body member b1. The weld bead wb is formed on the inner surface of the head 100. The weld bead wb is raised on the inner surface of the head 100. In Figures 10 and 11, the weld bead wb is shown as a black fill. The cross-sectional shape of the weld bead wb is irregular, but in Figures 10 and 11, the cross-sectional shape of the weld bead wb is schematically shown as a semicircle. Note that the weld bead wb is omitted from the cross-sectional views in Figures 4 to 7 and Figure 9.

[0123] The face member f1 and the body member b1 are joined by welding. The type of welding is not limited, and examples include laser welding, arc welding, gas welding, and resistance welding. Filler material (welding rod, etc.) may or may not be used. In this embodiment, laser welding is employed. The weld bead wb may be formed by the base material alone, by the filler material alone, or by the base material and filler material. In this embodiment, no filler material is used, and the weld bead wb is formed by the molten and solidified base material (body member b1 and face member f1). 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.

[0124] As shown in Figures 10 and 11, in each radial section, an outer surface reference line CV1 is determined that passes through the face center C1 and extends along the striking face 104a. If the striking face 104a is a curved surface, the outer surface reference line CV1 is a curve. In each radial section, the cross-sectional line of the striking face 104a has a point C2 1 mm away from the face center C1 on one side and a point C3 1 mm away from the face center C1 on the other side. These 1 mm are the path lengths of the cross-sectional line of the striking face 104a. The arc of a circle passing through the three points C1, C2 and C3 can be the outer surface reference line CV1.

[0125] The normal vector N1 of the impact face 104a at the face center C1 intersects with the inner surface 104b of the face. The intersection point C4 of the normal vector N1 and the inner surface 104b of the face is defined. In each radial section, the inner surface reference line CV2 is determined by translating the outer surface reference line CV1 to a position passing through the intersection point C4. That is, the inner surface reference line CV2 is a line that passes through the intersection point C4 and is parallel to the outer surface reference line CV1.

[0126] The portion that protrudes backward from the inner reference line CV2 may be defined as the rearward extension E1. The length D1 of the rearward extension E1 may be measured starting from the inner reference line CV2. The length D1 of the rearward extension E1 is measured along the direction of the normal N1. The length D1 of the rearward extension E1 is measured at each of the radial sections.

[0127] In the radial section of Figure 10, the face member f1 has a rearward extension E1 that extends from the outer edge of the face member f1 toward the back. The rearward extension E1 has a sole-side rearward extension Es provided on the sole side of the face member f1. In the radial section of Figure 10, the rearward extension E1 is not provided on the crown side of the face member f1. On the crown side of the face member f1, the length D1 of the rearward extension E1 is zero. On the crown side of the face member f1, there is a crown-side edge portion G1 formed by the absence of the rearward extension E1. The entire crown-side edge portion G1 is located between the outer surface reference line CV1 and the inner surface reference line CV2.

[0128] In the radial section of Figure 11, the face member f1 has a rearward extension E1 that extends from the outer edge of the face member f1 toward the back. The rearward extension E1 has a toe-side rearward extension Et provided on the toe side of the face member f1. In the radial section of Figure 11, the rearward extension E1 is not provided on the heel side of the face member f1. At the cross-sectional position in Figure 11 (the position of line BB in Figure 1), the rearward extension E1 does not exist due to the notch 119. Below the cross-sectional position in Figure 11, the rearward extension E1 (heel-side rearward extension Eh) exists (see Figure 3).

[0129] Referring to Figure 3, on the toe side of the face member f1, the length D1 of the rearward extension E1 decreases as it approaches the crown side (upper side). That is, the length D1 of the rearward extension Et on the toe side decreases as it approaches the crown side (upper side). On the heel side of the face member f1, the length D1 of the rearward extension E1 decreases as it approaches the crown side (upper side). That is, the length D1 of the rearward extension Eh on the heel side decreases as it approaches the crown side (upper side).

[0130] Figure 12 is a magnified view of a portion of Figure 10. The head 100 has a wall thickness t1. The wall thickness t1 is measured along the direction normal to the outer surface of the head 100. The wall thickness t1 is the distance from the inner surface of the head to the outer surface of the head.

[0131] From a strength standpoint, the thickness t1 of the face portion 104 may be 1.2 mm or more, more specifically 1.3 mm or more, and more specifically 1.4 mm or more. From a rebound performance standpoint, the thickness t1 of the face portion 104 may be 4.0 mm or less, more specifically 3.8 mm or less, and more specifically 3.6 mm or less.

[0132] In the welded joint between the face member f1 and the body member b1, the thickness t1 of the head 100 is increased by the weld bead wb. The rigidity is locally enhanced by the weld bead wb.

[0133] Of the weld beads wb, the weld bead wb1 located on the crown side (crown region CR) is connected to the crown side edge portion G1. The weld bead wb1 has an endpoint 130 on the body side. The thickness t1 at the endpoint 130 is the thickness t10. Preferably, the thickness t10 is 0.7 mm or more and 1.0 mm or less. The thickness t10 is smaller than the width LG of the crown side edge portion G1. The width LG is measured in a vertical cross section. The thickness t10 is larger than the thickness t1 of the sole side rear extension portion Es. A thickness change portion 132 is formed in the weld bead wb1 from the body side endpoint 130 toward the back side, where the thickness t1 continuously decreases. The face-to-back length of the thickness change portion 132 may be 3 mm or more and 20 mm or less.

[0134] In the face member f1, the entire edge of the rearward extension E1 and the crown-side edge G1 are located on the same plane PL. The edge of the sole-side rearward extension Es, the edge of the toe-side rearward extension Et, the edge of the heel-side rearward extension Eh, and the crown-side edge G1 are located on the same plane PL (see Figures 12 and 5 to 7). The joint surface 118 of the sole-side rearward extension Es, the joint surface 118 of the toe-side rearward extension Et, the joint surface 118 of the heel-side rearward extension Eh, and the crown-side edge G1 are located on the same plane PL. All joint surfaces 118 extend along the plane PL. The crown-side edge G1 extends along the plane PL.

[0135] When the plane PL is considered horizontal and the face member f1 is placed on this horizontal plane PL, the edges of the sole-side rearward extension Es, the toe-side rearward extension Et, the heel-side rearward extension Eh, and the crown-side edge G1 all come into contact with the horizontal plane PL. At this time, the only part that does not come into contact with the horizontal plane PL is the portion where the notch 119 is formed.

[0136] The edges of the body member b1 also lie on the same plane PL. That is, the entire joint surface 116 of the body member b1 lies on the same plane PL. The joint surface 116 extends along the plane PL.

[0137] This head 100 provides the following effects:

[0138] The face member f1 comprises the entire face portion 104 (impact face 104a). While rigidity tends to increase at welded joints, there are no welded joints in the face portion 104 (impact face 104a). As a result, the entire face portion 104 becomes more flexible, improving rebound performance.

[0139] From the perspective of preventing deformation and damage during welding, a certain thickness t1 is required for the welded area. Increasing the thickness t1 at the welded area can also increase the joint strength. However, when welding is performed at the rear extension E1 on the crown side, and the thickness t1 of this rear extension E1 is increased, the center of gravity of the head 100 tends to rise. In contrast, by welding the crown side of the face member f1 at the crown side edge G1, it is possible to utilize the part that originally has a relatively large thickness t1 (the transition area from the face part 104). Therefore, it is not necessary to increase the thickness of the rear extension E1 on the crown side as in the conventional method. As a result, the weight of the crown side of the head 100 can be reduced, and the center of gravity of the head 100 can be lowered. Lowering the center of gravity of the head 100 brings the point of impact closer to the sweet spot, especially when hitting a ball placed directly on the ground, improving rebound performance.

[0140] The width LG of the crown-side edge portion G1 is greater than the thickness t1 of the sole-side rear extension portion Es. This increases the welding joint strength on the crown side. In a configuration where the crown side has a rear extension portion E1, if the thickness t1 of the welded portion is made to be about the same as the width LG, the rear extension portion E1 becomes thicker, and the center of gravity of the head 100 tends to rise. By eliminating the rear extension portion E1 on the crown side and welding at the crown-side edge portion G1, it is possible to increase the width LG of the welded portion while reducing the weight of the crown side of the head 100.

[0141] As described above, a thickness change section 132 is provided in which the thickness t1 continuously decreases from the body-side endpoint 130 of the crown-side weld bead wb1 toward the back side. The thickness change section 132 makes it possible to increase the width LG of the weld while reducing the weight of the crown side of the head 100. Point 134 shown in Figure 10 is the point where the thickness t1 of the thickness change section 132 is the same as the thickness t1 (minimum value) of the sole-side rear extension Es. Towards the back from point 134, the thickness t1 of the crown section 106 is thinner than the thickness t1 of the sole-side rear extension Es. From the viewpoint of lowering the center of gravity of the head 100, the distance D2 from the inner surface reference line CV2 to point 134 is preferably smaller than the length D1 of the sole-side rear extension Es, and more preferably smaller than half the length D1. From the viewpoint of lowering the center of gravity of the head 100, the distance D2 from the inner reference line CV2 to point 134 is preferably 3 mm or less, more preferably 2 mm or less, and even more preferably 1 mm or less. This distance D2 may be zero, and point 134 may be located in front of the inner reference line CV2. The distance D2 is measured along the normal N1 of the striking face 104a at the face center C1.

[0142] In a configuration where the rearward extension portion E1 is eliminated on the crown side and the rearward extension portion E1 is present on the sole side, if the edge of the rearward extension portion E1 on the sole side and the edge portion G1 on the crown side are positioned on the same plane PL, the plane PL will be oriented obliquely with respect to the direction of the normal to the outer surface of the head (see Figure 12). As a result, the width LG of the crown side edge portion G1 can be increased, and the welding strength can be improved.

[0143] From the viewpoint of rebound performance, the length D1 of the rear extension Es on the sole side is preferably 6 mm or more, more preferably 7 mm or more, and even more preferably 8 mm or more. From the viewpoint of weldability, the length D1 of the rear extension Es on the sole side is preferably 20 mm or less, more preferably 15 mm or less, and even more preferably 12 mm or less.

[0144] At the welded area, a weld bead (raised area) is formed on the outer surface of the head 100. This weld bead needs to be removed by grinding. If this ground-down portion constitutes the contour line of the head 100 at address, the variation in the contour shape of the head 100 will be large. In the head 100, the sole-side rear extension Es, the toe-side rear extension Et, and the heel-side rear extension Eh are provided in the portion that forms the contour line at address. Therefore, welding is unnecessary in the portion that constitutes the contour line of the head 100, and the variation in the contour shape of the head 100 is suppressed. By suppressing this variation, the sense of incongruity in the appearance of the striking face 104a at address can be reduced. Note that the upper edge of the face portion 104 does not constitute the contour line of the head 100 at address. Therefore, grinding the weld bead at the crown-side edge portion G1 does not affect the contour shape of the head 100.

[0145] In the face member f1, the entire edge of the rearward-extending portion E1 and the crown-side edge portion G1 are located on the same plane PL. That is, the rear end of the face member f1, which is the welded portion, is located on the same plane PL. This makes it easier to process the edge portion of the face member f1. For example, the edge portion of the face member f1 can be cut along the plane by milling. Thus, processing becomes easier and processing accuracy can be improved. As a result, the accuracy of the butt joint with the body member b1 is improved, and variations in the shape of the finished head 100 can be reduced. Similarly, the front end (joint surface 116) of the body member b1 is also on the same plane PL. The same effect as with the face member f1 is achieved with the body member b1.

[0146] The center of gravity of the internal weight section 120 is located closer to the face than the head's center of gravity. Also, as shown in Figure 4, the base section 122 has a sloping portion where the upper surface 122a becomes lower towards the back, extending beyond the head's center of gravity. Therefore, more weight can be distributed to the underside of the head 100. On the other hand, by positioning the center of gravity of the protruding section 124 closer to the face than the head's center of gravity, the depth of the center of gravity is reduced. These configurations allow the sweet spot to be lowered. Lowering the sweet spot allows the point of impact when hitting a ball placed directly on the ground to be closer to the sweet spot. This improves rebound performance.

[0147] The following additional information is disclosed regarding the embodiments described above. [Note 1] A hollow golf club head having a face portion with the striking face facing forward, a crown portion, and a sole portion, It is formed by welding together a body member having an opening and a face member having the face portion and closing the opening. The face member has a rearward-extending portion that extends from the outer edge of the face portion toward the back side, The rearward extension comprises a sole-side rearward extension provided on the sole side of the face member, a toe-side rearward extension provided on the toe side of the face member, and a heel-side rearward extension provided on the heel side of the face member. A golf club head in which the crown side of the face member is provided with a crown-side edge portion formed by not providing the rearward-extending portion. [Note 2] The golf club head described in Appendix 1, wherein the edge of the rearward-extending portion on the sole side, the edge of the rearward-extending portion on the toe side, the edge of the rearward-extending portion on the heel side, and the crown side edge are located on the same plane. [Note 3] A weld bead is formed at the boundary between the crown-side edge portion and the body member. The golf club head according to Appendix 1 or 2, wherein the thickness of the body member at the body-side endpoint of the weld bead is 0.7 mm or more and 1.0 mm or less. [Note 4] A golf club head as described in any one of the appendices 1 to 3, wherein the length of the rearward extension on the sole side is 20 mm or less. [Note 5] A golf club head described in any one of the appendices 1 to 4, which is a fairway wood type head. [Explanation of Symbols]

[0148] 100... Golf club heads 104...Face section 104a...Hitting face 104b...Face interior 106... Crown section 108... Sole 110...Hosel section 112···Hosel hole 120...Internal weight part 122...Base of the internal weight section 124...Protrusions in the internal weight section f1...Face component b1... Body parts h1...Hollow part wb... weld bead k1... Outer edge of the striking face CR...Crown area SL... Sole area TE...Tow region HL...Healing Area C1...Face Center E1... Rear extension part Es...Sole side rear extension part Et...Toe side rear extension part Eh... Heel-side rear extension R... Radius of curvature at the boundary between the striking face and the outer surface of the crown Rt... Radius of curvature R at a position 15mm toe-side from the face center. Rc... Radius of curvature at the face center position R Rh... Radius of curvature R at a position 15mm heel-side from the face center. S... Radius of curvature at the boundary between the striking face and the outer surface of the sole St... Radius of curvature S at a position 15mm toe-side from the face center. Sc... Radius of curvature S at the face center position Sh... Radius of curvature S at a position 15mm heel-side from the face center.< / fc> < / tc> < / sc>

Claims

1. A hollow golf club head having a face portion with the striking face facing forward, a crown portion, and a sole portion, It is formed by welding together a body member having an opening and a face member having the face portion and closing the opening. The face member has a rearward-extending portion that extends from the outer edge of the face portion toward the back side, The rearward extension comprises a sole-side rearward extension provided on the sole side of the face member, a toe-side rearward extension provided on the toe side of the face member, and a heel-side rearward extension provided on the heel side of the face member. A golf club head in which the crown side of the face member is provided with a crown-side edge portion formed by not providing the rearward-extending portion.

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

3. A weld bead is formed at the boundary between the crown-side edge portion and the body member. The golf club head according to claim 2, wherein the thickness of the body member at the body-side endpoint of the weld bead is 0.7 mm or more and 1.0 mm or less.

4. The golf club head according to any one of claims 1 to 3, wherein the length of the rearward extension on the sole side is 20 mm or less.

5. A golf club head according to any one of claims 1 to 3, which is a fairway wood type head.

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