Golf Club Head

The present disclosure relates to a golf club head.

In recent years, various golf club heads devised to be improved in coefficient of restitution have been proposed, for example, as shown in Patent Documents 1 to 3 listed below.

Golf club heads having enhanced forgiveness on miss shots have been known. In such a golf club head, the thickness distribution of the face portion is improved in order that the drop in flight distance will become small even if the ball is hit at a position that deviates from an ideal impact position on the club face (for example, the face center, the same applies hereinafter).

On the other hand, in the case of professional golfers and advanced golfers who can always hit the ball at an ideal impact position, golf club heads having enhanced forgiveness on miss shots have little benefit in improving the flight distance.

Therefore, for the golfers who can hit the ball at an ideal impact position, technology that can further increase the flight distance of the ball is required.

The present disclosure was devised in view of the problems as described above, and a primarily objective of the present disclosure is to provide a golf club head in which the flight distance of a ball when hit at an ideal impact position can be further improved.

According to the present disclosure, a golf club head provided with a cavity therein, comprises a face portion having a club face for striking a ball, a crown portion, a sole portion, a toe and a heel, wherein

In the golf club head according to the present disclosure, as the above-described configuration is employed, it is possible to further improve the flight distance of a ball when hit at an ideal impact position.

Hereinafter, embodiments of the present disclosure will be described in detail in conjunction with accompanying drawings. Throughout all the embodiments, the same or common components are denoted by the same reference numerals, and redundant explanations are omitted.

are a perspective view, a plan view, and a front view, respectively, of a golf club headas an embodiment of the present disclosure (hereinafter simply referred to as the head). In, the headis under its reference state.

In this application, the “reference state” of a golf club head is such a state that the head is placed on a horizontal plane HP at its lie angle α and loft angle (not shown) specified for the head, with a shaft axis CL of the head lying within a reference vertical plane VP () orthogonal to the horizontal plane HP at the lie angle α as shown in.

In this application, descriptions are made assuming that the head is under the a reference state unless otherwise noted. In the case of the head alone, the “shaft axis CL” can be defined by the center line of the shaft insertion holeformed in the hosel portionof the head.

As shown in, a front-rear direction of the headunder the reference state is a direction x perpendicular to the above-mentioned reference vertical plane VP.

In the front-rear direction of the head, the side of the club faceis the front side, and the opposite side is the rear side.

Further, a toe-heel direction of the headunder the reference state is a direction parallel to both the above-mentioned horizontal plane HP and the reference vertical plane VP.

Furthermore, an up-down direction of the headunder the reference state is a direction perpendicular to the horizontal plane HP.

The headin this embodiment is a golf club head provided with a cavity (i) therein (see). Examples of this type of head include heads for wood-type golf clubs and hybrid-type golf clubs.

In this embodiment, the headis designed as a wood-type head made of metal material or materials.

As shown in, the headcomprises a face portion, a crown portion, a sole portion, a toeand a heel.

is a front view of the headshowing the face portion.is a cross-sectional view of the face portion of the headtaken along line V-V in.is a cross-sectional view of the face portion of the headtaken along line VI-VI in.

As shown in, the face portionhas an outer surface defining a club facefor hitting a ball, and an inner surfacefacing the cavity (i) of the head, The club facemay be provided with a bulge and/or a roll, for example.

As is clear from, the club facein this embodiment is a smoothly three-dimensionally curved surface which is convex toward the outside of the head.

The club facemay be provided with narrow grooves called face lines (not shown) extending in the toe-heel direction.

The club facehas a sweet spot SS, a face peripherally edge E and a face center FC.

In this application, the “sweet spot SS” of the club faceis a point of intersection of a normal line N with the club face, wherein the normal line N is a straight line drawn from the gravity center CG of the head to the club facenormally to the club face

In this application, the peripherally edge E of the club face defines the contour of the club face, and is defined as follows.

For each cross section (s1, s2, s3 - - - ) including the normal line N as shown in, firstly, obtain positions Pe on the outer contour line Lf of the head at which the curvature radius (r) is decreased and first becomes 200 mm in a course from the sweet spot SS toward the periphery of the club face as shown in, and then, obtain a curve passing through the obtained positions Pe, and define it as the peripheral edge E.

In this application, the radius of curvature at any position on a curved line may be determined as the radius of a circle passing through three points: a first point at said any position, a second point on the curved line at 1 mm toward one side of the first point along the curved line, and a third point on the curved line at 1 mm toward the other side of the first point along the curved line.

In this application, the face center FC is determined as follows.

(step 1) arbitrary-select a point P (not shown) on the club facewhich is regarded as being approximately center in the up-down direction and also approximately center in the toe-heel direction of the head.(step 2) determine a plane parallel with the toe-heel direction which passes through the point P and extends along the normal direction to the club faceat the point P.(step 3) obtain a midpoint Px of a line of intersection between the plane determined in step 2 and the club face(step 4) determine a plane parallel with the up-down direction which passes through the midpoint Px obtained in step 3 and extends along the normal direction to the club faceat this midpoint Px.(step 5) obtain a midpoint Py of a line of intersection between the plane determined in step 4 and the club face(step 6) determine a plane parallel with the toe-heel direction which passes through the midpoint Py obtained in step 5 and extends along the normal direction to the club faceat this midpoint Py.(step 7) obtain a new midpoint Px of a line of intersection between the plane determined in step 6 and the club face(step 8) determine a plane parallel with the up-down direction which passes through the new midpoint Px obtained in step 7 and extends along the normal direction to the club faceat this midpoint Px.(step 9) obtain a new midpoint Py of a line of intersection between the plane determined in step 8 and the club face

As described above, by repeating the steps such as step 1-step 9, midpoints Px and midpoints Py are sequentially obtained. And, during sequentially obtaining midpoints Py, when the distance between the newly obtained midpoint Py and the last obtained midpoint Py first becomes 0.5 mm or less, the position of the newly obtained midpoint Py is determined as the face center FC.

The crown portionextends from the face portiontoward the rear of the head so as to form the upper surface of the head.

On the heel side of the crown portion, a hosel portionis formed.

The hosel portionis provided with a shaft insertion holeinto which a tip end of a club shaft (not shown) is inserted and fixed.

The sole portionextends from the face portiontoward the rear of the head so as to form the bottom surface of the head.

The sole portionis, for example, defined as a portion visible in a bottom view of the head.

In the front view of the head, as shown in, the toeof the headmeans a position which is opposite to the hosel portionand farthest from the hosel portionin the toe-heel direction. The term “toe side” means a direction approaching the toe.

In the front view of the head, as shown in, the heelof the headmeans a position which is located on the hosel portionside and 0.875 inches above the horizontal plane HP. The term “heel side” means a direction approaching the heel.

The headin this example comprises a main portion made of a metal material or materials. As to the metal materials, for example, pure titanium, titanium alloys, stainless steels, maraging steels, aluminum alloys, magnesium alloys, tungsten-nickel alloys, etc. can be used although not particularly limited.

Further, a part of the head(for example, the crown portion) may be made of a non-metallic material such as fiber-reinforced resin.

In this embodiment, the headis made of a titanium alloy.

As shown in, the club faceof the face portioncomprises a central partin which a face center FC is located, and a transitional partformed outside the central part.

The central partis a region in which the face portion has a constant thickness tc.

In this application, the constant thickness tc in the central partmeans not only a case where the thickness is completely the same continuously along the club face, but also a case where the thickness varies within a range of manufacturing errors and a range of measurement errors which may inevitably occur.

Regarding the latter case, based on the thickness of the face portionat the face center FC, if the difference from this thickness is within +/−0.05 mm, then a portion having such difference is considered to be a portion having the same thickness, namely, the central part.

Incidentally, when face lines or face grooves are formed on the club face, the thickness of such grooved part of the face portionis determined assuming that the face groove is filled up, in other words, assuming that there is no face groove.

The central parthas a surface area of not less than 100 sq.mm.

In, the boundary positionof the central partis indicated by a short-dashes line. The surface area of the central partis measured on the club face

If the above-mentioned face lines or face grooves are formed on the club face, then the surface area of the central partis determined assuming that the face grooves are filled up.