Patent Description:
<CIT> discloses a wood-type golf club head used for striking ball off ground and tee, which has a club head structure which defines a hollow interior region, a crown opening, and a sole opening, and a crown insert which is coupled to crown opening.

It is a main object of the present invention to provide a golf club head that is larger in high-resilience area in a face section and higher in durability than a golf club head in the related art.

A golf club head according to the present invention includes a face section, a crown section, a sole section, a heel section, and a toe section. A hollow section separated from the outside is formed inside the golf club head. The face section includes, on a back surface, a first thick section disposed substantially at the center in a toe-heel direction going from the toe section to the heel section, a second thick section disposed adjacent to the sole section relative to the first thick section, and a thin section thinner than the first thick section and the second thick section and disposed so as to surround the entire periphery of the first thick section and the entire periphery of the second thick section. The first thick section includes a first portion disposed substantially at a center in both the toe-heel direction and a crown-sole direction going from the crown section to the sole section and having a longitudinal direction coincident with the toe-heel direction, and a second portion protruding from a part at a center of the first portion in the longitudinal direction toward the crown section.

According to the present invention, it is possible to provide a golf club head that is larger in high-resilience area in a face section and higher in durability than a golf club head in the related art.

With reference to the drawings, an embodiment according to the present invention will be described below. Note that, in the following drawings, the same or corresponding parts are denoted by the same reference numerals, and no redundant description will be given of such parts.

With reference to <FIG>, a structure of a golf club head <NUM> according to the present embodiment will be described. As an example of the present embodiment, golf club head <NUM> illustrated in <FIG> is a wood-type golf club head used for a driver golf club. Golf club head <NUM> may be a golf club head used for a fairway wood golf club or utility club.

Note that <FIG> is a front view of golf club head <NUM> that is set on a horizontal plane so as to form a predetermined loft angle and lie angle with the horizontal plane (hereinafter, referred to as a set state). A first direction Z illustrated in <FIG> and <FIG> is an upward direction. A second direction Y illustrated in <FIG> is a direction intersecting first direction Z and in parallel with the horizontal plane. A third direction X illustrated in <FIG> and <FIG> is a direction intersecting first direction Z and second direction Y and in parallel with the horizontal plane.

As illustrated in <FIG>, golf club head <NUM> includes a face section <NUM>, a crown section <NUM>, a sole section <NUM>, a heel section <NUM>, a toe section <NUM>, a back section <NUM>, and a hosel section <NUM>.

As illustrated in <FIG>, face section <NUM> has a striking surface 1A and a back surface 1B positioned on the opposite side from striking surface 1A and facing the hollow section. As illustrated in <FIG>, face section <NUM> has an outer peripheral surface 1C connected to crown section <NUM>, sole section <NUM>, heel section <NUM>, and toe section <NUM>. Outer peripheral surface 1C connects striking surface 1A and back surface 1B and extends in a direction intersecting striking surface 1A and back surface 1B. Of outer peripheral surface 1C, an upper end surface section 1C2 positioned on an upper side in the set state is connected to crown section <NUM>. Of outer peripheral surface 1C, a lower end surface section 1C3 positioned on a lower side in the set state is connected to sole section <NUM>. For example, a plurality of score lines (not illustrated) are formed on striking surface 1A. Details of face section <NUM> will be described later.

Crown section <NUM> is a section disposed above face section <NUM> in the set state. Crown section <NUM> serves as a top of golf club head <NUM>. Crown section <NUM> is contiguous to face section <NUM>. Crown section <NUM> has a lower end surface connected to upper end surface section 1C2 of face section <NUM>.

Sole section <NUM> is a section positioned below face section <NUM> in the set state. Sole section <NUM> serves as a bottom of golf club head <NUM>. Sole section <NUM> has a sole surface 3A that comes into contact with the ground when hitting a ball. Sole surface 3A is a curved surface. Sole section <NUM> is contiguous to face section <NUM>. Sole section <NUM> has an upper end surface connected to lower end surface section 1C3 of face section <NUM>.

Heel section <NUM> is a section extending from a lower end of hosel section <NUM> to sole section <NUM>. Heel section <NUM> is contiguous to face section <NUM>. Toe section <NUM> is a section connecting crown section <NUM> and sole section <NUM> on a side remote from hosel section <NUM>. Back section <NUM> is a section smoothly connecting crown section <NUM> and sole section <NUM> on a side remotest from striking surface 1A in a direction perpendicular to striking surface 1A. A shaft <NUM> is connected to hosel section <NUM> of a golf club <NUM> (to be described later).

Hereinafter, a direction going from toe section <NUM> to heel section <NUM> along face section <NUM> is referred to as a toe-heel direction. A direction going from crown section <NUM> to sole section <NUM> along face section <NUM> is referred to as a crown-sole direction. A direction going from face section <NUM> to the back section is referred to as a face-back direction.

As illustrated in <FIG>, golf club head <NUM> has a hollow section <NUM> formed therein. Hollow section <NUM> is separated from the outside of golf club head <NUM> by face section <NUM>, crown section <NUM>, sole section <NUM>, heel section <NUM>, toe section <NUM>, back section <NUM>, and hosel section <NUM>. Hollow section <NUM> is positioned between face section <NUM> and back section <NUM> in the face-back direction, between crown section <NUM> and sole section <NUM> in the crown-sole direction, and between heel section <NUM> and toe section <NUM> in the toe-heel direction.

A material of which face section <NUM>, toe section <NUM>, heel section <NUM>, crown section <NUM>, sole section <NUM>, back section <NUM>, and hosel section <NUM> are each made includes at least one selected from the group consisting of pure titanium (Ti), a titanium alloy, iron (Fe), stainless steel, and special steel, for example.

The titanium alloy of which face section <NUM>, toe section <NUM>, heel section <NUM>, crown section <NUM>, sole section <NUM>, back section <NUM>, and hosel section <NUM> are each made may be any titanium alloy, and examples of such a titanium alloy include an α titanium alloy (for example, 5AL-<NUM>. 5V), an α-β titanium alloy (for example, Ti-6Al-4V, Ti811 (Ti-8Al-1Mo-1V)), and a β titanium alloy (for example, SAT2041, Ti-15V-3Cr-3Sn-3AL). The stainless steel of which face section <NUM>, crown section <NUM>, sole section <NUM>, heel section <NUM>, toe section <NUM>, back section <NUM>, and hosel section <NUM> are each made may be any stainless steel, and examples of such stainless steel include austenitic stainless steel (for example, SUS304), martensitic stainless steel (for example, SUS431), and precipitation hardening stainless steel (for example, SUS630). Examples of the special steel of which face section <NUM>, crown section <NUM>, sole section <NUM>, heel section <NUM>, toe section <NUM>, back section <NUM>, and hosel section <NUM> are each made include high-tensile steel, ultra-high-tensile steel, ausforming steel, maraging steel, and spring steel.

Face section <NUM>, crown section <NUM>, sole section <NUM>, heel section <NUM>, toe section <NUM>, back section <NUM>, and hosel section <NUM> may be made of the same material or different materials. As an example, a material of which crown section <NUM>, sole section <NUM>, heel section <NUM>, toe section <NUM>, back section <NUM>, and hosel section <NUM> is each made is an α-β titanium alloy, and a material of which face section <NUM> is made is a β titanium alloy.

<FIG> is a cross-sectional view as viewed from an arrow IV-IV in <FIG>. <FIG> is a cross-sectional view taken along a plane passing through the center of face section <NUM> in the toe-heel direction and extending in the crown-sole direction. <FIG> is a cross-sectional view as viewed from an arrow V-V in <FIG>. <FIG> is a cross-sectional view taken along a plane passing through a point closer to toe section <NUM> than the center of face section <NUM> in the toe-heel direction and extending in the crown-sole direction. <FIG> is a cross-sectional view as viewed from an arrow VI-VI in <FIG>. <FIG> is a cross-sectional view taken along a plane passing through the center of face section <NUM> in the crown-sole direction and extending in the toe-heel direction. <FIG> is a rear view of face section <NUM> alone as viewed from back surface 1B. In <FIG>, solid lines illustrated inside the contour indicating outer peripheral surface 1C indicate ridge lines of an uneven structure formed on back surface 1B.

As illustrated in <FIG>, face section <NUM> has a plurality of portions different in thickness. A thickness of face section <NUM> corresponds to a width of face section <NUM> in the direction perpendicular to striking surface 1A. A thickness distribution of face section <NUM> is determined based on the uneven structure on back surface 1B illustrated in <FIG>.

As illustrated in <FIG>, face section <NUM> mainly includes a first thick section <NUM>, a second thick section <NUM>, and a thin section <NUM>. In <FIG>, hatching is applied to first thick section <NUM> and second thick section <NUM> in order to make first thick section <NUM> and second thick section <NUM> clear. All areas that are not hatched in <FIG> serve as thin section <NUM>.

First thick section <NUM> is disposed substantially at the center in the toe-heel direction. First thick section <NUM> has a first portion 11A and a second portion 11B. First portion 11A of first thick section <NUM> is disposed substantially at the center in the toe-heel direction and the crown-sole direction. Second portion 11B of first thick section <NUM> is disposed substantially at the center in the toe-heel direction. Note that "substantially at the center in the toe-heel direction" means, for example, an area extending by <NUM> toward both the toe section and the heel section from a first imaginary center straight line passing through the center in the toe-heel direction and extending in the crown-sole direction. "Substantially at the center in the crown-sole direction" means, for example, an area extending by <NUM> toward both the crown section and the sole section from a second imaginary center straight line passing through the center in the crown-sole direction and extending in the toe-heel direction. First thick section <NUM> is, for example, the thickest portion of face section <NUM>.

Second thick section <NUM> is disposed closer to sole section <NUM> than first thick section <NUM>. Second thick section <NUM> is disposed between first thick section <NUM> and sole section <NUM> in the crown-sole direction. Second thick section <NUM> is thinner than first thick section <NUM>. Second thick section <NUM> is not in contact with sole section <NUM>. A second thin portion <NUM> (to be described later) of thin section <NUM> is disposed between second thick section <NUM> and sole section <NUM>.

Thin section <NUM> is thinner than first thick section <NUM> and second thick section <NUM>. Thin section <NUM> is disposed so as to surround the entire periphery of first thick section <NUM> and the entire periphery of second thick section <NUM>.

As illustrated in <FIG>, thin section <NUM> has a plurality of portions different in thickness. The thickest portion of thin section <NUM> is thinner than the thinnest portion of first thick section <NUM> and the thinnest portion of second thick section <NUM>. Face section <NUM> smoothly changes in thickness at a connection portion between an outer edge of first thick section <NUM> and an outer edge of thin section <NUM>. Face section <NUM> smoothly changes in thickness at a connection portion between an outer edge of second thick section <NUM> and the outer edge of thin section <NUM>. The thickest portion of thin section <NUM> is, for example, the connection portion between the outer edge of first thick section <NUM> and the outer edge of thin section <NUM>.

As illustrated in <FIG>, thin section <NUM> includes a first thin portion <NUM>, a second thin portion <NUM>, a third thin portion <NUM>, a fourth thin portion <NUM>, and a fifth thin portion <NUM>, which are defined based on the ridge lines or positions on back surface 1B illustrated in <FIG>. First thin portion <NUM> is disposed between first thick section <NUM> and second thick section <NUM>. Second thin portion <NUM> is a portion of face section <NUM> connected to sole section <NUM>. Second thin portion <NUM> is partially disposed between second thick section <NUM> and sole section <NUM>. Third thin portion <NUM> is a portion of face section <NUM> connected to crown section <NUM>. Third thin portion <NUM> is partially disposed between first thick section <NUM> and crown section <NUM>. Fourth thin portion <NUM> is a portion of face section <NUM> connected to heel section <NUM>. Fourth thin portion <NUM> is partially disposed between first thick section <NUM>, second thick section <NUM>, and first thin portion <NUM>, and heel section <NUM>. Fifth thin portion <NUM> is a portion of face section <NUM> connected to toe section <NUM>. Fifth thin portion <NUM> is partially disposed between first thick section <NUM>, second thick section <NUM>, and first thin portion <NUM>, and toe section <NUM>. In other words, crown section <NUM>, sole section <NUM>, heel section <NUM>, and toe section <NUM> are each connected to thin section <NUM> of face section <NUM>.

As illustrated in <FIG>, first portion 11A has a longitudinal direction coincident with the toe-heel direction and a lateral direction coincident with the crown-sole direction. Second portion 11B protrudes from a part at the center of first portion 11A in the longitudinal direction toward crown section <NUM>. Second portion 11B has, for example, a longitudinal direction coincident with the toe-heel direction and a lateral direction coincident with the crown-sole direction. An end of first portion 11A adjacent to crown section <NUM> is connected to an end of second portion 11B adjacent to sole section <NUM>. The maximum thickness of first portion 11A is equal to, for example, the maximum thickness of second portion 11B.

As illustrated in <FIG>, first thick section <NUM> has an inverted T shape when face section <NUM> is viewed from back surface 1B. Herein, the inverted T shape is defined as a three-dimensional area including only first portion 11A having a longitudinal direction coincident with the toe-heel direction and a lateral direction coincident with the crown-sole direction, and second portion 11B protruding from a part at the center of first portion 11A in the longitudinal direction toward crown section <NUM>. As described above, second portion 11B has, for example, a longitudinal direction coincident with the toe-heel direction and a lateral direction coincident with the crown-sole direction.

In the cross section illustrated in <FIG>, face section <NUM> mainly includes first thick section <NUM>, second thick section <NUM>, and first thin portion <NUM>, second thin portion <NUM>, and third thin portion <NUM> of thin section <NUM>. As illustrated in <FIG> and <FIG>, second thin portion <NUM> is, for example, thinner than first thin portion <NUM>. A lower end surface of second thin portion <NUM> serves as lower end surface section 1C3 of face section <NUM>. Third thin portion <NUM> is, for example, thinner than first thin portion <NUM>. An upper end surface of third thin portion <NUM> serves as upper end surface section 1C2 of face section <NUM>. At least either second thin portion <NUM> or third thin portion <NUM> is the thinnest portion of face section <NUM> in the cross section illustrated in <FIG>. Second thin portion <NUM> is, for example, thinner than third thin portion <NUM> and is thus the thinnest portion of face section <NUM> in the cross section illustrated in <FIG>.

In the cross section illustrated in <FIG>, third thin portion <NUM>, first thick section <NUM>, first thin portion <NUM>, second thick section <NUM>, and second thin portion <NUM> are arranged side by side in the crown-sole direction from crown section <NUM> to sole section <NUM> in this order. In the cross section illustrated in <FIG>, face section <NUM> gradually changes in thickness in the crown-sole direction.

In the cross section illustrated in <FIG>, face section <NUM> mainly includes first thick section <NUM>, first thin portion <NUM>, second thin portion <NUM>, and third thin portion <NUM>, but does not include second thick section <NUM>. In the cross section illustrated in <FIG>, face section <NUM> gradually decreases in thickness from first thick section <NUM> to sole section <NUM>. In the cross section illustrated in <FIG>, third thin portion <NUM>, first thick section <NUM>, first thin portion <NUM>, and second thin portion <NUM> are arranged side by side in the crown-sole direction from crown section <NUM> to sole section <NUM> in this order. In the cross section illustrated in <FIG>, thin section <NUM> gradually decreases in thickness from first thin portion <NUM> to second thin portion <NUM>.

In the cross section illustrated in <FIG>, face section <NUM> mainly includes first thick section <NUM>, fourth thin portion <NUM>, and fifth thin portion <NUM>. In the cross section illustrated in <FIG>, fourth thin portion <NUM>, first thick section <NUM>, and fifth thin portion <NUM> are arranged side by side in the toe-heel direction from heel section <NUM> to toe section <NUM> in this order. Heel section <NUM> is connected to fourth thin portion <NUM>. Toe section <NUM> is connected to fifth thin portion <NUM>. In the cross section illustrated in <FIG>, face section <NUM> gradually changes in thickness in the toe-heel direction.

As illustrated in <FIG>, first thick section <NUM>, second thick section <NUM>, first thin portion <NUM>, and second thin portion <NUM> each have, for example, a longitudinal direction coincident with the toe-heel direction and a lateral direction coincident with the crown-sole direction.

The width of each of first thick section <NUM>, second thick section <NUM>, first thin portion <NUM>, and second thin portion <NUM> in the toe-heel direction is not limited to any specific width. The width may be determined as desired in a manner that depends on the face shape.

The width of each of first thick section <NUM>, second thick section <NUM>, first thin portion <NUM>, and second thin portion <NUM> in the crown-sole direction is not limited to any specific width. The width may be determined as desired in a manner that depends on the face shape.

When golf club head <NUM> is a head of a fairway wood golf club or a head of a utility golf club, first thick section <NUM> has a thickness greater than or equal to <NUM> and less than or equal to <NUM>, second thick section <NUM> has a thickness greater than or equal to <NUM> and less than or equal to <NUM>, and second thin portion <NUM> and third thin portion <NUM> each have a thickness greater than or equal to <NUM> and less than or equal to <NUM>, for example. When golf club head <NUM> is a driver golf club, first thick section <NUM> has a thickness greater than or equal to <NUM> and less than or equal to <NUM>, second thick section <NUM> has a thickness greater than or equal to <NUM> and less than or equal to <NUM>, and second thin portion <NUM> and third thin portion <NUM> each have a thickness greater than or equal to <NUM> and less than or equal to <NUM>, for example.

A method for manufacturing golf club head <NUM> may be any manufacturing method, but, for example, members each made by forging or casting are welded together to form golf club head <NUM>. Crown section <NUM>, sole section <NUM>, heel section <NUM>, and toe section <NUM> are formed in a single body by solid casting, for example. The single body has a hollow section and an opening formed therein, the opening communicating with the hollow section. Face section <NUM> covers the opening. Outer peripheral surface 1C of face section <NUM> is welded to an end surface of the opening of the molded body. In this case, a parting line is formed, due to casting, on an edge of the end surface of the opening adjacent to the hollow section, so that face section <NUM> can be defined as a portion including striking surface 1A and surrounded by the parting line.

In golf club head <NUM>, first thick section <NUM> and second thick section <NUM> are each entirely surrounded by thin section <NUM>, so that thin section <NUM> of face section <NUM> is connected to sole section <NUM>, specifically, to second thin portion <NUM>. This can make a whole area between first thick section <NUM> and second thin portion <NUM> in face section <NUM> of golf club head <NUM> higher in resilience than the end adjacent to the sole section disclosed in PTL <NUM>. This can make golf club head <NUM> larger in high-resilience area in the face section than the golf club head disclosed in PTL <NUM> in which the end adjacent to the sole section is formed as a thick section. Such a golf club head <NUM> makes face section <NUM> flexible even when a ball is hit at a point shifted from the sweet spot toward the sole section, that is, off-center shot, for example. This allows golf club head <NUM> to make a difference in distance between the sweet-spot shot and the off-center shot small as compared with the golf club head disclosed in PTL <NUM>.

Face section <NUM> of golf club head <NUM> further includes second thick section <NUM> disposed closer to sole section <NUM> than first thick section <NUM>. When face section <NUM> does not include second thick section <NUM>, face section <NUM> may become insufficient in durability. Further, when face section <NUM> does not include second thick section <NUM> and has a whole area between first thick section <NUM> and second thin portion <NUM> of face section <NUM> formed as a thin section, face section <NUM> may become too high in resilience. In golf club head <NUM>, face section <NUM> includes second thin portion <NUM> and second thick section <NUM>, thereby providing face section <NUM> with high durability and high resilience.

In golf club head <NUM>, in the cross-section illustrated in <FIG>, third thin portion <NUM> of face section <NUM> is connected to crown section <NUM>. This makes a whole area between third thin portion <NUM> connected to crown section <NUM> and second thin portion <NUM> connected to sole section <NUM> in face section <NUM> of golf club head <NUM> flexible. That is, this makes golf club head <NUM> larger in high-resilience area in the face section than the golf club head disclosed in PTL <NUM> in which the end adjacent to the sole section and the end adjacent to the crown section are each formed as a thick section. Such a golf club head <NUM> makes face section <NUM> flexible even when a ball is hit at a point shifted from the sweet spot toward the crown section, that is, off-center shot, for example.

As illustrated in <FIG>, golf club <NUM> includes golf club head <NUM>, shaft <NUM>, and a grip <NUM>. Shaft <NUM> has one end attached to hosel section <NUM> of golf club head <NUM>. Shaft <NUM> has the other end attached to grip <NUM>.

In the present example, a result of evaluation of a characteristic time (CT) value of a face section will be described. As an example, golf club head <NUM> described above was prepared. As a comparative example, a golf club head having a thick section formed extending from the center of the face section to the lower end of the face section and having a thin section formed only in an area adjacent to the crown section, the toe section, and the heel section relative to the thick section was prepared. In other words, as the comparative example, a golf club head having neither the second thick section nor the thin section disposed so as to surround the entire periphery of the second thick section was prepared. The CT value is measured according to a procedure defined by the United States Golf Association (USGA).

<FIG> illustrates CT value measurement points <NUM> to <NUM> on the face section of a driver. As illustrated in <FIG>, the sweet spot was set as measurement point <NUM>. The measurement points <NUM> to <NUM> were each set at a corresponding intersection of six imaginary straight lines drawn in a lattice pattern centered on measurement point <NUM>. An interval in the toe-heel direction between three imaginary straight lines of the six imaginary straight lines extending in the crown-sole direction was set to <NUM>. An interval in the crown-sole direction between three imaginary straight lines extending in the toe-heel direction was set to <NUM>. Note that, in this example, measurement points <NUM>, <NUM>, <NUM> were set on the first thick section. In this example, measurement points <NUM>, <NUM>, <NUM> were set on second thin portion <NUM>. In this example, measurement points <NUM>, <NUM>, <NUM> were set on third thin portion <NUM>. Further, in the comparative example, measurement points <NUM>, <NUM>, <NUM>, <NUM>, <NUM> were set on the thick section, and measurement points <NUM>, <NUM>, <NUM>, <NUM> were set on the thin section.

Table <NUM> shows ratios obtained by normalizing the CT values measured at measurement points <NUM> to <NUM> of the example and the comparative example with the CT value measured at measurement point <NUM> of the example set to <NUM>.

Table <NUM> shows that the example is higher than the comparative example in the ratios of measurement points <NUM>, <NUM>, <NUM> positioned closer to the sole section than measurement point <NUM>. In particular, the ratio of the CT value of measurement point <NUM> of the example was greatly improved as compared with the ratio of the CT value of measurement point <NUM> of the comparative example, and was almost equal to the ratios of the CT values of measurement point <NUM> and measurement point <NUM> of the example arranged side by side with measurement point <NUM> in the toe-heel direction.

It should be understood that the embodiment disclosed herein is illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims.

Claim 1:
A golf club head comprising:
a face section (<NUM>);
a crown section;
a sole section;
a heel section; and
a toe section,
wherein a hollow section separated from an outside is formed,
the face section includes, on a back surface, a first thick section (<NUM>) disposed substantially at a center in a toe-heel direction going from the toe section to the heel section, a second thick section (<NUM>) disposed closer to the sole section than the first thick section, and a thin section (<NUM>) thinner than the first thick section and the second thick section and disposed so as to surround an entire periphery of the first thick section and an entire periphery of the second thick section, and
the first thick section includes a first portion (11A) disposed substantially at a center in both the toe-heel direction and a crown-sole direction going from the crown section to the sole section and having a longitudinal direction coincident with the toe-heel direction, and a second portion (11B) protruding from a part at a center of the first portion in the longitudinal direction toward the crown section.