GOLF CLUB HEAD

The golf club head includes a face portion, a plurality of score lines formed in the face portion and extending in a toe-heel direction, and a plurality of convex portions formed in the face portion, projecting from reference plane which includes edges of each of the plurality of score lines, and extending in the toe-heel direction. The plurality of convex portions include a first convex portion and a second convex portion formed between adjacent score lines. A projecting height of the first convex portion and/or a width in an orthogonal direction of the toe-heel direction of the first convex portion is larger than that of the second convex portion.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to and the benefit of Japanese Patent Application No. 2021-208410 filed on Dec. 22, 2021, the entire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a golf club head.

Description of the Related Art

There has been known a technique of improving the spin performance of a struck golf ball by score lines or grooves thinner than score lines on a face portion (for example, Japanese Patent Laid-Open Nos. 2019-217196 and 2019-217195).

However, the related art has room for improvement in terms of the spin performance of the face portion.

SUMMARY OF THE INVENTION

It is an object of the present invention to improve the spin performance of the face portion.

According to one aspect of the present invention, there is provided a golf club head comprising:a face portion;a plurality of score lines formed in the face portion and extending in a toe-heel direction; anda plurality of convex portions formed in the face portion, projecting from reference plane which includes edges of each of the plurality of score lines, and extending in the toe-heel direction,wherein the plurality of convex portions include a first convex portion and a second convex portion formed between adjacent score lines, anda projecting height of the first convex portion and/or a width in an orthogonal direction of the toe-heel direction of the first convex portion is larger than that of the second convex portion.

DESCRIPTION OF THE EMBODIMENTS

FIG.1shows an external view and a partial enlarged view of a golf club head1according to an embodiment of the present invention.FIG.1illustrates an example in which the present invention is applied to an iron type golf club head. The present invention is suitable for an iron type golf club head and, more particularly, for middle iron, short iron, and wedge type golf club heads. More specifically, the present invention is suitable for manufacturing a golf club head with a loft angle of 30° (inclusive) to 70° (inclusive) and a head weight of 240 g (inclusive) to 320 g (inclusive). However, the present invention is also applicable to wood type and utility (hybrid) type golf club heads.

The golf club head1includes a face portion2and a hosel portion5. The face portion2forms a striking surface for striking a golf ball. A shaft (not shown) is attached to the hosel portion5. InFIG.1, an arrow D1 indicates a toe-heel direction, and reference symbols T and H indicate the toe side and the heel side, respectively. An arrow D2indicates a vertical direction (a direction between a top line4and a leading edge3) orthogonal to the D1 direction and along the face portion2. Reference symbols U and L indicate the upper side (top line 4 side) and the lower side (leading edge3side), respectively, upon grounding the sole portion of the head1.

A plurality of score lines6and a plurality of convex portions7are formed in the face portion2. The score lines6and the convex portions7will be described with reference toFIG.2in addition toFIG.1.FIG.2is a sectional view taken along a line A - A inFIG.1. This is a sectional view of the golf club head1showing the structures of adjacent two score lines6and the structure between these score lines6.

Each score line6is a straight groove extending in the D1 direction. The plurality of score lines6are aligned parallel to each other in the D2 direction. Although the score lines6are aligned at equal intervals (equal pitches) in this embodiment, they may be aligned at different intervals. In this embodiment, each score line6has the same cross-sectional shape throughout its entire longitudinal portion except for its two ends (toe- and heel-side ends). Also, the score lines6have the same cross-sectional shape.

Each score line6includes a pair of side walls (side portions)61and a bottom wall (bottom portion)62, and has a trapezoidal cross-sectional shape bilaterally symmetric about a center line in the D2 direction. Note that the cross-sectional shape of the score line6is not limited to a trapezoidal shape, and may be other shapes such as a V shape. Rounded portions are formed on edge portions63of each score line6. The radius of the rounded portion is, for example, 0.05 mm (inclusive) to 0.3 mm (inclusive). The face portion2includes a reference plane10. The reference plane10is a flat plane and includes the edge of each edge portion63of the score line6. In other word, a virtual plane including the edge of each edge portion63is the reference plane10.

A depth H1of the score line6(the distance between the bottom wall62and the reference plane10) is preferably 0.3 mm or more. When the golf club head1is intended for athletics, the depth H1 is set to 0.5 mm or less to comply with a relevant rule. A width W1 (the width defined by the 30-degree measurement rule) of the score line6is preferably 0.6 mm or more. When the golf club head1is intended for athletics, the width W1 is set to 0.9 mm or less to comply with a relevant rule.

The plurality of convex portions7are formed over the entire region of the face portion2. Each convex portion projects from the reference plane10, and extends linearly in the D1 direction parallel to the score line6. In this embodiment, each convex portion projects from the reference plane10in the normal direction of the reference plane10. The plurality of convex portions7are aligned parallel to each other in the D2 direction. At the time of striking a golf ball, its surface is readily caught between the adjacent convex portions, so that the spin performance of the golf ball can be improved.

In this embodiment, the plurality of convex portions7include two kinds of convex portions, that is, a convex portion8and a convex portion9having different specifications. In other words, the convex portion7is a general term for the convex portion8and the convex portion9. In this embodiment, the plurality of convex portions7include these two kinds of convex portions alone, but may include three or more kinds of convex portions. Four arrays of convex portions8and three arrays of convex portions9are formed between two score lines6adjacent to each other in the D2 direction. In other words, seven arrays of convex portions7in total are formed between the two score lines6adjacent to each other in the D2 direction. The number of convex portions7formed between two score lines6adjacent to each other in the D2 direction is five to nine, and preferably seven to nine.

In this embodiment, four arrays of convex portions8and three arrays of convex portions9are formed in the same alignment structure between arbitrary two score lines6adjacent to each other in the D2 direction. A deviation of the spin performance depending on the striking position in the face portion2can be suppressed.

As shown inFIG.2, the cross-sectional shape of each of the convex portion8and the convex portion9along a cutting line in the D2 direction is a trapezoid. However, the cross-sectional shape of each of the convex portion8and the convex portion9may be another shape such as a triangle, a rectangle, or a circular arced shape. A width W2 of the convex portion8in the D2 direction and a width W3 of the convex portion9in the D2 direction have a relationship expressed by W2 > W3. A projecting height H2 of the convex portion8from the reference plane10to its top and a projecting height H3 of the convex portion9from the reference plane10to its top have a relationship expressed by H2 > H3. In this manner, both the projecting height and the width in the D2 direction of the convex portion8are larger than those of the convex portion9. Since the convex portion8and the convex portion9having different projecting heights and widths are formed, it is possible to improve the drainage performance and prevent clogging of grass and the like. Thus, the spin performance can be further improved.

In this embodiment, alignment pitches P2 of the convex portions8are equal pitches, and the alignment pitch P2 is, for example, 500 µm ≤ P2 ≤ 1500 µm. In this embodiment, alignment pitches P3 of the convex portions9are equal pitches, and the alignment pitch P3 is, for example, 500 µm ≤ P3 ≤ 1500 µm. The convex portion8and the convex portion9adjacent to each other in the D2 direction are aligned at an equal interval (pitch).

In this embodiment, the convex portions8and the convex portions9are alternately formed in the D2 direction between the adjacent score lines6. A deviation of the spin performance depending on the striking position in the face portion2can be suppressed.

In the first embodiment, both the projecting height and the width in the D2 direction of the convex portion8are larger than those of the convex portion9. However, one of the projecting height and the width in the D2 direction of the convex portion8may be larger than that of the convex portion9. In the example shown inFIG.3A, the relationship between a projecting height H2 of a convex portion8and a projecting height H3 of a convex portion9is expressed by H2 = H3. On the other hand, the relationship between a width W2 of the convex portion8and a width W3 of the convex portion9is expressed by W2 > W3.

Further, in the first embodiment, the convex portions8and the convex portions9are alternately formed in the D2 direction between the adjacent score lines6. However, various alignment modes can be adopted as the alignment mode of the convex portions8and the convex portions9. In the example shown inFIG.3B, a plurality of convex portions8and a plurality of convex portions9are formed so as to be aligned in a D2 direction. More specifically, the convex portions8and the convex portions9are aligned in the order of the convex portion8→ the convex portion8→ the convex portion9→ the convex portion9→ the convex portion8→ the convex portion8from the side of a top line4in the D2 direction. Since the convex portions9are arranged continuously in the D2direction, it is possible to improve the drainage performance and prevent clogging of grass and the like between the convex portions.

InFIG.4, a plurality of convex portions11recessed on the side of a reference plane10in the projecting height direction of a convex portion7are formed in a plurality of convex portions7. The concave portions11include a concave portion12formed in a convex portion8, and a concave portion13formed in a convex portion9. In other words, the concave portion11is a general term for the concave portion12and the concave portion13. Since a droplet attached on a face portion2passes through the concave portion11and traverses the convex portion7, the drainage performance of the face portion2can be improved. The improvement in the drainage performance of the face portion2enhances the spin performance (the effect of suppressing a decrease in spin amount) in, for example, rainy weather.

FIG.5Ais a sectional view taken along a line B - B inFIG.4, andFIG.5Bis a sectional view taken along a line C - C inFIG.4. In this embodiment, the depth of the concave portion12is equal to the projecting height of the convex portion8. Accordingly, the bottom surface of the concave portion12is located on the same plane as the reference plane10, and the concave portion12divides the convex portion8halfway in a D1direction. Similarly, the depth of the concave portion13is equal to the projecting height of the convex portion9. Accordingly, the bottom surface of the concave portion13is located on the same plane as the reference plane10, and the concave portion13divides the convex portion9halfway in the D1 direction. Since the bottom surface of each of the concave portion12and the concave portion13is located on the same plane as the reference plane10, the drainage performance for droplets attached on the face portion2and stored between adjacent convex portions can be improved.

As shown inFIG.5B, a distance S in the D1 direction between arbitrary concave portions12adjacent to each other on the same convex portion8is preferably 10 mm or less. It is possible to suppress the deviation of the drainage performance in the toe-heel direction. Similarly, although not shown inFIG.5B, for the concave portion13, the distance in the D1 direction between arbitrary concave portions13adjacent to each other on the same convex portion9is preferably 10 mm or less. The width of each of the concave portion12and the concave portion13in a D2 direction is, for example, 15 µm (inclusive) to 100 µm (inclusive).

The plurality of concave portions11are formed in a continuous pattern over the entire region of the face portion2. Since the plurality of concave portions11are formed in the continuous pattern, the drainage performance of the face portion2can be made uniform, and a deviation of the spin performance depending on the striking position in the face portion2can be suppressed. The design of the face portion2can also be improved.FIG.6Ashows the basic pattern. The pattern in this embodiment is formed by using a symbol11aas one unit and arranging the symbols11aregularly in the D1 direction and the D2 direction. The concave portions11are formed in portions where this pattern overlaps the plurality of convex portions7.

The symbol11a is formed in a Y shape constituted by a vertical straight line extending in the D2 direction and two inclined straight lines branching from the vertical straight line and inclined in opposite directions. Accordingly, each of the plurality of concave portions11is located on any of a virtual line L1overlapping the vertical straight line and virtual lines L2and L3overlapping the inclined straight lines. Note that the virtual line L2is a virtual line inclined from the toe side to the heel side from the side of a leading edge3toward the side of a top line7. The virtual line L3is a virtual line inclined from the heel side to the toe side from the side of the leading edge3toward the side of the top line4and intersecting the virtual line L2. Even when striking a ball with a golf club head1while opening or closing the face portion2with respect to the target direction, a large change in the drainage performance of the face portion2can be prevented. In addition, when striking a ball while opening or closing the face portion2with respect to the target direction, the golf ball is easily caught by the edge of the concave portion11, so that the spin performance can be improved.

In the third embodiment, the depth of the concave portion12is equal to the projecting height of the convex portion8. However, the depth of the concave portion12may be smaller than the projecting height of the convex portion8.FIG.6Bis a sectional view showing this example, and corresponds to a sectional view taken along the line C - C inFIG.4. In the example shown inFIG.6B, the bottom surface of a concave portion12is located at a position higher than a reference plane10(a position on the top side of a convex portion8). Since the convex portion8is continuous in a D1direction with no interruption, when striking a ball while facing a face portion2toward the target direction, the spin performance can be improved while maintaining the drainage performance by the concave portion12. Although not shown, the depth of a concave portion13may also be smaller than the projecting height of a convex portion9. The concave portion12and the concave portion13may have different depths.

When the plurality of concave portions11are formed in a continuous pattern, the basic pattern is not limited to the example shown inFIG.6A.FIGS.7and8are external views of golf club heads 1 having different basic patterns.

FIG.9Ashows a basic pattern of a plurality of concave portions11formed in a continuous pattern in the example shown inFIG.7. The pattern shown inFIG.9Ais formed by using a symbol11bas one unit and arranging the symbols11bregularly in a D1direction and a D2 direction. The concave portions11are formed in portions where this pattern overlaps a plurality of convex portions7.

The symbol11bis a polygon, particularly, a quadrangle, and more particularly, a parallelogram. Each side of the symbol11bextends in a direction intersecting the D2direction. Each of virtual lines L4and L5is a virtual line overlapping a long side of the symbol11band inclined with respect to the D1direction. The plurality of concave portions11include concave portions located on the virtual lines L4and L5. Note that the virtual line L4is a virtual line inclined from the toe side to the heel side from the side of a leading edge3toward the side of a top line4. The virtual line L5is a virtual line inclined from the heel side to the toe side from the side of the leading edge3toward the side of the top line4and intersecting the virtual line L4. Even when striking a ball with the golf club head1while opening or closing a face portion2with respect to the target direction, a large change in the drainage performance of the face portion2can be prevented. In addition, when striking a ball while opening or closing the face portion2with respect to the target direction, the golf ball is easily caught by the edge of the concave portion11, so that the spin performance can be improved.

The symbol11bmay be not a parallelogram but a rectangle or a square, and may be not a quadrangle but a triangle, a pentagon, a hexagon, a circle, or an oval.

Next,FIG.9Bshows the basic pattern of the plurality of concave portions11formed in the continuous pattern in the example shown inFIG.8. The pattern shown inFIG.9Bis constituted by two kinds of polygonal lines11cand11dshown inFIG.9C, each of which has regular bends. The pattern shown inFIG.9Bis formed by arranging a plurality of the polygonal lines11cregularly in the D1 direction and arranging a plurality of the polygonal lines lid regularly in the D2 direction. The concave portions11are formed in portions where this pattern overlaps the plurality of convex portions7.

Each of the polygonal line11cand the polygonal line lid is generally inclined with respect to the D1 direction, and the inclination of the polygonal line11cis different from the inclination of the polygonal line11d. In the pattern shown inFIG.9B, the polygonal line11cand the polygonal line11dintersect each other. Since the multiple polygonal lines11cand polygonal lines11dintersect each other, a network of water channels is formed, and the drainage performance can be improved.

In the third to fifth embodiment, by quantifying the relationship between the number of the convex portions7and the number of the concave portions11between adjacent two score lines6and using it as an index, the design efficiency of the golf club head1can be increased.FIG.10Ais a view for explaining an example. In the example shown inFIG.10A, three arrays of convex portions8and six arrays of convex portions9are formed between adjacent two score lines6. The total number of convex portions7is nine. In addition, three concave portions12and two concave portions13are formed.

At an arbitrary position in an D1 direction, a virtual reference line extending in a D2 direction is drawn so as to traverse the two score lines6. Let X be the number of the convex portions7intersecting the virtual reference line, and Y be the number of concave portions11intersecting the virtual reference line. An index Z is set to Z = Y/X. In the example shown inFIG.10A, three virtual reference lines L11 to L13 are exemplarily shown.

For the virtual reference line L11, the index Z = 2/9 ≈ 0.22. For the virtual reference line L12, the index Z = 0/9 ≈ 0. For the virtual reference line L13, the index Z = 3/9 ≈ 0.33.

In the example shown inFIG.10B, three arrays of the convex portions8and four arrays of the convex portions9are formed between the adjacent two score lines6. The total number of the convex portions7is seven. In addition, three concave portions12and two concave portions13are formed. In the example shown inFIG.10B, three virtual reference lines L21 to L23 are exemplarily shown.

For the virtual reference line L21, the index Z = 2/7 ≈ 0.29. For the virtual reference line L22, the index Z = 0/7 ≈ 0. For the virtual reference line L23, the index Z = 3/7 ≈ 0.43.

In terms of the spin performance, the total number of the convex portions7between adjacent two score lines6is preferably seven or more. On the other hand, in terms of the space, drainage performance, and clogging between the adjacent two score lines6, the total number of the convex portions7between the adjacent two score lines6is preferably nine or less. In terms of achieving both the drainage performance and the spin performance, it is preferable that a position with no concave portion11, a position with a few concave portions11, and a position with many concave portions11exist in the D2 direction. For example, as in the example shown in each ofFIGS.10A and10B, it is preferable that a position with no concave portion11(L12 or L22), a position with a few concave portions11(L11 or L21), and a position with many concave portions11(L13 or L23) exist.

From the viewpoints as described above, when a virtual reference line is drawn at an arbitrary position in the D2 direction, it has one of indices Z1 to Z3 expressed as:

0.22<Z2<0.29; or

By setting the number of the convex portions7and the number of the concave portions11in the D2 direction so as to satisfy these three index ranges alone and setting a distance S in the D1 direction between arbitrary concave portions11adjacent to each other on the same convex portion7to 10 mm or less as described above, a surface structure that further suppresses a deviation of the spin performance depending on the striking position and a deviation of the drainage performance can be obtained.

A formation method of convex portions7and concave portions11will be described next. As a golf club head1, for example, a primary molded product without the convex portions7and the concave portions11is manufactured by forging or casting. Then, the convex portions7and the concave portions11are formed in the primary molded product. After that, coating and a surface treatment are performed to complete the golf club head1. The primary molded product may be formed with or without score lines6. When the primary molded product includes no score line6, it is possible to form the score lines6upon forming the convex portions7and the concave portions11. The primary molded product may be formed from a single member or multiple members. When the primary molded product is formed from multiple members, it may be formed from, for example, a face forming member which forms a face portion2and a head body which forms the part other than the face portion2. In this case, the face forming member and the head body may be combined after the convex portions7and the concave portions11are formed in the face forming member.

The convex portions7and the concave portions11can be formed by laser processing or cutting.FIGS.11A and11Bexemplify a case in which the convex portions7and the concave portions11are formed by laser processing. A primary molded product1′ in which the convex portions7and the concave portions11are to be formed is fixed to a laser irradiation device (not shown) via a jig100. The laser irradiation device includes an irradiation unit101which emits laser light. The convex portions7and the concave portions11can be formed while irradiating the face portion2with laser light emitted by the irradiation unit101, and relatively moving the face portion2(primary molded product 1’) or irradiation unit101.

FIG.11Cexemplifies a case in which the convex portions7and the concave portions11are formed by cutting. The primary molded product 1′ is fixed to an NC milling machine via the jig100. The NC rotatably driven about the Z-axis, and a cutting tool (end mill) is attached to the lower end of the spindle102. As in the case of laser processing, the convex portions7and the concave portions11are formed while relatively moving the face portion2(primary molded product 1’) or cutting tool.

Note that after the formation of the convex portions7and the concave portions11, a surface treatment for increasing the hardness of the face portion2is preferably performed. Examples of such a surface treatment are a carburizing treatment, nitriding treatment, soft nitriding treatment, PVD (Physical Vapor Deposition) treatment, ion plating, DLC (Diamond-Like Carbon) treatment, and plating treatment. Especially surface treatments such as a carburizing treatment and nitriding treatment, which modify the surface without forming another metal layer on the surface, are preferable. The surface of the face portion2may be covered with a plating layer.