Golf Club Head

The present disclosure relates to a golf club head.

In a typical golf club, the center of gravity of the head is located away from the axis of the golf club shaft toward the toe of the head. Therefore, during the downswing, so-called toe-down may occur as shown in.

The toe-down is a phenomenon in which the toe side of the golf club head becomes lower due to the centrifugal force during the downswing.

Such toe-down changes the position or posture of the golf club head at impact, which will worsen the flight distance and direction of the hit golf ball.

The following Patent Document 1 discloses a conventional technique for suppressing such toe-down phenomenon.

In the golf club head of Patent Document 1, the outer surface of the crown portion is provided with a protrusion located at a specific position such that the protrusion increases a force (drag force) being capable of canceling the centrifugal force during downswing, thereby suppressing the toe-down phenomenon.

A golf club head provided with a protrusion as described above can suppress the toe-down during the downswing. But, due to the presence of the protrusion, the frequency of hitting sound tends to become lower. This is a new problem because many golfers tend to prefer higher frequency ball hitting sound. Thus, the golf club head is still required to be improved in ball hitting sound.

The present disclosure was made in view of the above-mentioned problem, and a primary objective of the present disclosure is to provide a golf club head which can prevent the frequency of ball hitting sound from becoming lower while suppressing the toe-down phenomenon occurring during downswing.

According to the present disclosure, a golf club head has a cavity therein, and, in a reference state of the golf club head placed on a horizontal plane at its specified lie angle and loft angle, comprise:

In the golf club head according to Present Disclosure, the lowering of the frequency of the ball hitting sound can be suppressed, while suppressing the toe-down during the downswing.

Embodiments of the present disclosure will now be described in detail in conjunction with accompanying drawings.

The drawings may include exaggerations or representations different from the actual dimensional proportions of the structures in order to facilitate understanding of the present disclosure.

Identical or common components in different embodiments are given the same reference numerals, and redundant descriptions will be omitted.

The specific configurations and structures illustrated in the embodiments and drawings are for understanding the present disclosure, and the present disclosure is not limited thereto.

are a plan view, a front view and a side view from the heel side, respectively, of a golf club headas a first embodiment of the present disclosure (hereinafter, simply referred to as the “head”).

are a perspective view of the headviewed from the heel side and a perspective view of the headviewed from the rear side.

In, the headcomprises a face portion, a crown portion, a sole portion, a hosel, a toe T and a heel H in this example.

In, the headis under its reference state.

In this application, the “reference state” of the headmeans a state in which the headis set on a horizontal plane HP at its lie angle α () and loft angle β () specified for the head. Incidentally, the lie angle α and loft angle β are, for example, listed in product catalogs and the like.

Further, the reference state is such that a club shaft axis CL of the headlies in a reference vertical plane VP defined as being perpendicular to the above-said horizontal plane HP while the headis held at the lie angle α and the loft angle β as shown in.

The club shaft axis CL corresponds to the center line of a shaft insertion holewhich is formed in the hoselof the headand into which a tip end of a club shaft is inserted and fixed.In this application, the descriptions are made based on that the headis under the reference state unless otherwise noted.

Further, the reference state is such that the face angle is set at 0 degrees. In other words, a tangent to the club faceat a face center FC extends in parallel to the toe-heel direction in the plan view of the headas shown in.

As shown in, a front-rear direction of the headunder the reference state is a direction perpendicular to the above-mentioned reference vertical plane VP. In the front-rear direction of the head, the side of the face portionis 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.

In this embodiment, the headhas a hollow structure having a cavity (i) therein (shown inas described later).

The headcan be configured as a head used for a driver, a fairway wood or a hybrid, for example.

In the embodiment shown in, the headis for a driver.

For example, when the headis for a driver, it may have a loft angle β of about 7 to 13 degrees, a head weight of 180 to 210 grams, and a head volume of 300 to 470 cc.

The face portionhas a club facewhich is a surface for hitting a ball.

The face portionis formed in a thin plate shape in this example, and the outer surface (front surface) of the face portionforms the club facefor hitting a ball.The club faceis, for example, provided with a bulge and a roll. Thereby, the club faceis formed as a three-dimensional curved surface which is convex toward the outside of the head.The club faceis usually provided with grooves called face lines extending in the toe-heel direction. Such grooves are however omitted in the drawings showing the embodiments of the present disclosure.

The club faceis a region surrounded by its peripheral edge E.

In this application, the peripheral edge E of the club faceis defined as follows.Firstly, obtain a sweet spot SS of the club faceas 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 faceSecondly, for each cross section (s, s, s. . . ) including the normal line N as shown in, obtain positions Pe on the outer contour line Lf of the head at which the curvature radius (r) first becomes 200 mm in a course from the sweet spot SS toward the periphery of the club face as shown in.Thirdly, obtain a curve passing through the obtained positions Pe, and define as the peripheral edge E.In the case that the outer contour line Lf includes face lines or face grooves formed in the club face, the outer contour line Lf is defined assuming that the face grooves are filled and there is no face groove.For example, the curvature radius (r) at any position on the outer contour line Lf 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 line Lf at 1 mm toward one side of the first point along the line Lf, and a third point on the line Lf at 1 mm toward the other side of the first point along the line Lf.

The club facehas a face center FC. In this application, the face center FC is a center point on the club facewhich is defined as follows.

(step 1) arbitrary-select a point P 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 faceAs 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 considered to be 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.

The crown portionis defined as a portion which is visible in the plan view, for example, shown in, and from which the club faceis excluded.On the heel H side of the crown portion, there is formed a hosel.The hoselis provided with a shaft insertion holeinto which the tip end of a club shaft (not shown) is inserted and fixed.

The crown portionis, for example, composed of a thin plate-like member, and its outer or upper surface includes a curved surfacethat is convex toward the upside so as to define a crown apex.

The crown apexis an uppermost position on the curved surfacesThe curved surfacein this example is a curved surface whose height decreases continuously from the crown apextoward the toe T side, the face portionside, the heel H side and the rear side.

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

The sole portionis defined as a portion which is, for example, visible in a bottom view of the head.In the headin the present embodiment, while extending toward the periphery of the head, as shown in, the sole portionis curved upward and connected to the periphery of the crown portion. The connection between the sole portionand the crown portionis made through an arc surface with a relatively small radius of curvature in the cross-section, so the connecting portion is provided with relatively high bending rigidity.

The face portion, the crown portionand the portionof the headare made of a metal material or metal materials, for example.

As 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 thereto.

The crown portionis provided, in the curved surface, with a protrusion.

The protrusionis a part locally protruding from the curved surfaceThe protrusionhas a protruding height which is defined as being measured from a virtual curved surface in the normal direction thereto, wherein the virtual curved surface is a virtual extension of the curved surfaceshow examples of the virtual curved surface (two-dot chain line) and the protruding height h.In the embodiment shown in, the protrusionhas the protruding height h whose maximum is approximately 5 mm.

Such protrusionhas the effect of suppressing the toe-down phenomenon as will be described later.

Preferable examples of the protrusionwill be described later.

In the front view of the headunder the reference state viewed from the face portionside, as shown in, the protrusiondoes not constitute a first profile line Cof the head which is the outer contour line of the head in the front view. In other words, the protrusionis invisible in substance when the headunder the reference state is viewed from the front of the head.

Hereinafter, this feature may be referred to as the first featureof the present disclosure.

show the headunder its vertical state.

The vertical state is such that the headunder the reference state is rotated around an axis extending in parallel to the front-rear direction while keeping the club shaft axis CL of the headwithin the reference vertical plane VP, until the club shaft axis CL of the headbecomes perpendicular to the horizontal plane HP.