HOLLOW GOLF CLUB HEAD

Abstract

This invention provides a hollow golf club head comprising a face portion, a crown portion, a sole portion, a side portion, and a hosel portion. A crown projecting portion in which the crown portion partly projects upward is formed at a position including a face center in the face-side region of the crown portion, and the thickness of the crown projecting portion gradually decreases toward the back.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hollow golf club head.

2. Description of the Related Art

Conventionally, as a club head which can increase the flight distance with improved rebound characteristics, a golf club head with a specific outer shell structure has been proposed (Japanese Patent Laid-Open No. 10-263118). This golf club head is provided with a deformation assisting portion so as to increase the flexure of the face portion or the displacement of the face portion relative to the golf club head at the time of impact.

With the club head according to Japanese Patent Laid-Open No. 10-263118, the flexure or relative displacement of the face portion increases, so the elastic deformation of the face portion increases, thus reducing the deformation of a ball acting as a viscoelastic body. Therefore, the energy loss reduces, so the flight distance improves.

Also, FIG. 4 in Japanese Patent Laid-Open No. 10-263118 shows a triangular, low elastic modulus portion 14A which is provided in a crown portion 2 as the above-mentioned deformation assisting portion. The low elastic modulus portion 14A is configured by forming a triangular through-hole having a top line 6 as its base in the crown portion, and filling the through-hole with a material having a low Young's modulus.

Unfortunately, the golf club head described in Japanese Patent Laid-Open No. 10-263118 still has room for improvements in terms of increasing the launch angle and initial velocity of a struck ball.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of the above-mentioned situation, and has as its object to provide a hollow golf club head which attains a larger launch angle and higher initial velocity of a struck ball than the conventional hollow golf club head, thereby increasing the flight distance of the ball as compared to the latter head.

According to an aspect of the present invention, there is provided a hollow golf club head comprising a face portion, a crown portion, a sole portion, a side portion, and a hosel portion, wherein a crown projecting portion in which the crown portion partly projects upward is formed at a position including a face center in a face-side region of the crown portion, and a thickness of the crown projecting portion gradually decreases toward a back.

According to another aspect of the present invention, there is provided a hollow golf club head comprising a face portion, a crown portion, a sole portion, a side portion, and a hosel portion, wherein a crown projecting portion in which the crown portion partly projects upward is provided at a position including a face center in a face-side region of the crown portion, and the crown projecting portion is formed using a material having a Young's modulus lower than a Young's modulus of a portion other than the crown projecting portion in the crown portion.

In the hollow golf club head according to the present invention, the sole portion means a portion which extends backward from the lower portion of the face portion to form the bottom portion of the head, the crown portion means a portion which extends backward from the upper portion of the face portion to form the upper portion of the head, and the side portion means a portion which extends backward from the portion between the upper portion and lower portion of the face portion to form the side portion of the head. The above-mentioned side portion includes a toe-side side portion, heel-side side portion, and back-side side portion.

In the present invention, the shapes and thicknesses of the face portion, sole portion, and side portion can appropriately be set. The shape and thickness of a region other than a crown projecting portion in the crown portion can also appropriately be set.

The golf club head according to the present invention can appropriately be formed as a head for a hollow golf club such as a driver, a fairway wood, or a utility club (hybrid club).

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an embodiment of a hollow golf club head according to the present invention;

FIG. 2 is a front view of the golf club head shown in FIG. 1;

FIG. 3 is a side view of the golf club head shown in FIG. 1 when viewed from the heel side;

FIG. 4 is a sectional view taken along a line S-S in FIG. 1;

FIG. 5 is a sectional view showing the barycentric position on the face surface, and the angle formed between the face portion and the crown portion;

FIG. 6 is a plan view showing another embodiment of a hollow golf club head according to the present invention;

FIG. 7 is a front view of the golf club head shown in FIG. 6;

FIG. 8 is a side view of the golf club head shown in FIG. 6 when viewed from the heel side;

FIG. 9 is a sectional view taken along a line S-S in FIG. 6; and

FIG. 10 is a sectional view showing the barycentric position on the face surface, and the angle formed between the face portion and the crown portion.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

The present invention will be described in detail below with reference to the accompanying drawings. FIGS. 1 to 4 show an embodiment of a hollow golf club head (driver head) according to the present invention; in which FIG. 1 is a plan view, FIG. 2 is a front view, FIG. 3 is a side view when viewed from the heel side, and FIG. 4 is a sectional view taken along a line S-S in FIG. 1. Note that a face member is not illustrated in FIG. 4.

A golf club head 10 according to this embodiment is obtained by fixing, using plasma welding, a face member 24 into a face opening portion 22 in a head body 20 including a sole portion 12, crown portion 14, side portion 16, and hosel portion 18. The head body 20 is made of Ti-6Al-4V, and the face member 24 is made of Ti-15Mo-5Zr-3Al.

In the golf club head 10 according to this embodiment, a crown projecting portion 28 in which the crown portion 14 partly projects upward is formed at a position including a face center 26 (indicated by an alternate long and short dashed line) in the face-side region of the crown portion 14. Also, the crown projecting portion 28 according to this embodiment is positioned above a barycentric position P on the face surface. The face center 26 is a normal to a flat surface, which passes through a point at which the sole portion 12 comes into contact with the flat surface when the golf club head 10 is set on the flat surface at a normal lie angle. The barycentric position P on the face surface is a point at which a normal L to the golf club head 10, which is dropped from the center of gravity G of the golf club head 10 intersects with the face surface, as shown in FIG. 5.

The crown projecting portion 28 is continuous with the upper edge portion of a face portion 30, its flat surface shape is an almost quadrangle having an almost arcuated back-side side (see FIG. 1), its front surface shape is an almost arcuated shape (see FIG. 2), and its side surface shape includes an almost arcuated shape on the face side and a downwardly inclined shape at the back-side end portion (see FIGS. 3 and 4). Note that a band-shaped bulging portion 32 which slightly bulges out upward is formed in the region of the crown portion 14, which is on the back side with respect to the crown projecting portion 28.

The thickness of the crown projecting portion 28 gradually decreases toward the back. More specifically, in this embodiment, the crown projecting portion 28 includes a face-side end portion 28x having a thickness of about 1.7 mm, and a back-side end portion 28y having a thickness of about 0.6 mm.

Also, in this embodiment, the projection height c of the back-side end portion of the crown projecting portion 28 from the crown surface is about 2.5 mm, and the projection height of the band-shaped bulging portion 32 from its two lateral side portions is about 4 mm.

Moreover, in this embodiment, the distance A of the crown portion in the toe-to-heel direction is 126 mm, the distance a of the crown projecting portion in the toe-to-heel direction is 48 mm, the ratio a/A is [(48/126)×100%]=about 38%, the distance of the crown portion in the face-to-back direction is 102 mm, the distance b of the crown projecting portion in the face-to-back direction is 23 mm, and the ratio b/B is [(23/102)×100%]=about 23%.

In this embodiment, the angle θ formed between the face portion 30 and the crown portion 14 is larger in the region in which the crown projecting portion 28 is formed than in the regions of the crown portion 14, which are on both the heel and toe sides with respect to the crown projecting portion 28, and this produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball. More specifically, the angle θ between the face portion 30 and the crown portion 14 is about 75° in the region in which the crown projecting portion 28 is formed, and is about 40° in the regions of the crown portion 14, which are on both the heel and toe sides with respect to the crown projecting portion 28.

When a driver was manufactured using the driver head according to this embodiment, it attains a relatively large launch angle and relatively high initial velocity of a struck ball, thereby increasing the flight distance of the ball.

Note that the hollow golf club head according to the present invention is not limited to the above-described embodiment, and can be changed into various forms without departing from the scope of the present invention. For example, the flat surface shape, front surface shape, and side surface shape of the crown projecting portion can appropriately be selected.

In the present invention, the thickness of the face-side end portion of the crown projecting portion is preferably 1.5 to 3.0 mm and more preferably 1.7 to 2.7 mm, and that of the back-side end portion of the crown projecting portion is preferably 0.5 to 1.2 mm and more preferably 0.6 to 0.8 mm. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball.

In the present invention, the projection height of the back-side end portion of the crown projecting portion from the crown surface is preferably 1 to 4 mm and more preferably 1 to 2.5 mm. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball.

In the present invention, the ratio [(a/A)×100%] of the distance a of the crown projecting portion in the toe-to-heel direction to the distance A of the crown portion in the toe-to-heel direction is preferably 20% to 60% and more preferably 30% to 50%. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball. More specifically, the distance a of the crown projecting portion in the toe-to-heel direction is preferably 30 to 70 mm and more preferably 45 to 55 mm.

In the present invention, the ratio [(b/B)×100%] of the distance of the crown projecting portion in the face-to-back direction to the distance B of the crown portion in the face-to-back direction is preferably 10% to 40% and more preferably 20% to 30%. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball. More specifically, the distance b of the crown projecting portion in the face-to-back direction is preferably 15 to 30 mm and more preferably 20 to 25 mm.

Although a method of manufacturing a golf club head according to the present invention is not particularly limited, a golf club head can be manufactured by, for example, sealing a face opening portion in a head body with a face member. In this case, although neither a material nor shaping method for the head body is particularly limited, titanium, a titanium alloy, stainless steel, or an amorphous alloy, for example, can be used as the material, and the casting method can be used as the shaping method. In the present invention, the crown portion of the head body has a complex shape due to the presence of the crown projecting portion, so at least the crown portion is preferably manufactured by the casting method. Although neither a material nor shaping method for the face member is particularly limited either, titanium, a titanium alloy, stainless steel, or an amorphous alloy, for example, can be used as the material, and the forging method, the press forming method of pressing a plate material, or the die casting method is preferable as the shaping method.

Although a method of joining the head body and the face member is not particularly limited, these members are preferably joined by plasma welding, laser welding, or electron beam welding and especially by plasma welding from the viewpoint of, for example, finishing the joined portion with a good appearance and improving the weight precision of the golf club head. In this case, a known plasma welding technique of fusing a material to be welded using high-temperature energy produced by a plasma arc, and solidifying it again, thereby performing welding can be used for plasma welding. A known laser welding technique which uses a gas laser such as a CO laser or a CO₂ laser, or a solid-state laser such as a YAG laser can be used for laser welding. A known electron beam welding technique which uses an appropriately output electron beam can be used for electron beam welding.

Second Embodiment

The present invention will be described in detail below with reference to the accompanying drawings. FIGS. 6 to 9 show another embodiment of a hollow golf club head (driver head) according to the present invention; in which FIG. 6 is a plan view, FIG. 7 is a front view, FIG. 8 is a side view when viewed from the heel side, and FIG. 9 is a sectional view taken along a line S-S in FIG. 1. Note that a face member is not illustrated in FIG. 9.

A golf club head 110 according to this embodiment is obtained by fixing, using plasma welding, a face member 124 into a face opening portion 122 in a head body 120 including a sole portion 112, crown portion 114, side portion 116, and hosel portion 118, and fixing, using plasma welding, a crown projecting portion forming member 125 into a crown opening portion 123. The head body 120 is made of Ti-6Al-4V (Young's modulus: about 115 G), the face member 124 is made of Ti-15Mo-5Zr-3Al, and the crown projecting portion forming member 125 is made of Ti-15Mo-3Al (annealed material; Young's modulus: about 65 GPa).

In the golf club head 110 according to this embodiment, by fixing the crown projecting portion forming member 125 into the crown opening portion 123, as described above, a crown projecting portion 128 in which the crown portion 114 partly projects upward is formed at a position including a face center 126 (indicated by an alternate long and short dashed line) in the face-side region of the crown portion 114. Also, the crown projecting portion 128 according to this embodiment is positioned above a barycentric position P on the face surface. The face center 126 is a normal to a flat surface, which passes through a point at which the sole portion 112 comes into contact with the flat surface when the golf club head 110 is set on the flat surface at a normal lie angle. The barycentric position P on the face surface is a point at which a normal L to the golf club head 110, which is dropped from the center of gravity G of the golf club head 110 intersects with the face surface, as shown in FIG. 10.

The crown projecting portion 128 is continuous with the upper edge portion of a face portion 130, its flat surface shape is an almost quadrangle having an almost arcuated back-side side (see FIG. 6), its front surface shape is an almost arcuated shape (see FIG. 7), and its side surface shape includes an almost arcuated shape on the face side and a downwardly inclined shape at the back-side end portion (see FIGS. 8 and 9). Note that a band-shaped bulging portion 132 which slightly bulges out upward is formed in the region of the crown portion 114, that is on the back side with respect to the crown projecting portion 128.

The thickness of the crown projecting portion 128 gradually decreases toward the back. More specifically, in this embodiment, the crown projecting portion 128 includes a face-side end portion 128x having a thickness of about 1.7 mm, and a back-side end portion 128y having a thickness of about 0.6 mm.

Also, in this embodiment, the projection height c of the back-side end portion of the crown projecting portion 128 from the crown surface is about 2.5 mm, and the projection height of the band-shaped bulging portion 132 from its two lateral side portions is about 4 mm.

Moreover, in this embodiment, the distance A of the crown portion in the toe-to-heel direction is 126 mm, the distance a of the crown projecting portion in the toe-to-heel direction is 48 mm, the ratio a/A is [(48/126)×100%]=about 38%, the distance of the crown portion in the face-to-back direction is 102 mm, the distance b of the crown projecting portion in the face-to-back direction is 23 mm, and the ratio b/B is [(23/102)×100%]=about 23%.

In this embodiment, the angle θ formed between the face portion 130 and the crown portion 114 is larger in the region in which the crown projecting portion 128 is formed than in the regions of the crown portion 114, which are on both the heel and toe sides with respect to the crown projecting portion 128, and this produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball. More specifically, the angle θ between the face portion 130 and the crown portion 114 is about 75° in the region in which the crown projecting portion 128 is formed, and is about 40° in the regions of the crown portion 114, which are on both the heel and toe sides with respect to the crown projecting portion 128.

When a driver was manufactured using the driver head according to this embodiment, it attains a relatively large launch angle and relatively high initial velocity of a struck ball, thereby increasing the flight distance of the ball.

Note that the hollow golf club head according to the present invention is not limited to the above-described embodiment, and can be changed into various forms without departing from the scope of the present invention. For example, the flat surface shape, front surface shape, and side surface shape of the crown projecting portion can appropriately be selected.

In the present invention, a portion other than the crown projecting portion in the crown portion is formed using a material having a Young's modulus of preferably 100 GPa or more, and the crown projecting portion is formed using a material having a Young's modulus of preferably 65 to 95 GPa and more preferably 65 to 85 GPa. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball.

Also, the difference between the Young's modulus of the material which forms the portion other than the crown projecting portion in the crown portion and that of the material which forms the crown projecting portion is preferably 15 to 50 GPa and more preferably 30 to 50 GPa. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball.

More specifically, examples of the material which has a high Young's modulus and forms the portion other than the crown projecting portion in the crown portion include titanium, a titanium alloy, stainless steel, and an amorphous alloy, and examples of the material which has a Young's modulus lower than the former material having a high Young's modulus include titanium, a titanium alloy, stainless steel, and an amorphous alloy.

A first high-strength titanium alloy is especially preferable as the material which has a high Young's modulus and forms the portion other than the crown projecting portion in the crown portion, and a second high-strength titanium alloy is especially preferable as the material which has a low Young's modulus and forms the crown projecting portion. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball.

A detailed example of the above-mentioned first high-strength titanium alloy is Ti-6Al-4V that is a general alpha-beta alloy. Ti-6Al-4V has a Young's modulus of about 115 GPa.

A detailed example of the above-mentioned second high-strength titanium alloy is Ti-15Mo-3Al. An annealed material made of Ti-15Mo-3Al has a Young's modulus of about 65 GPa, and therefore has a relatively low Young's modulus and excellent spring property, among beta titanium alloys. Other examples of the second high-strength titanium alloy include Ti-22V-3Nb (Young's modulus: about 72 GPa), and Ti-15Mo-5Zr-3Al (Young's modulus: about 75 GPa).

In the present invention, the face-side end portion of the crown projecting portion is preferably continuous with the upper edge portion of the face portion. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball.

In the present invention, the projection height of the back-side end portion of the crown projecting portion from the crown surface is preferably 1 to 4 mm and more preferably 1 to 2.5 mm. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball.

In the present invention, the ratio [(a/A)×100%] of the distance a of the crown projecting portion in the toe-to-heel direction to the distance A of the crown portion in the toe-to-heel direction is preferably 20% to 60% and more preferably 30% to 50%. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball. More specifically, the distance a of the crown projecting portion in the toe-to-heel direction is preferably 30 to 70 mm and more preferably 45 to 55 mm.

In the present invention, the ratio [(b/B)×100%] of the distance of the crown projecting portion in the face-to-back direction to the distance B of the crown portion in the face-to-back direction is preferably 10% to 40% and more preferably 20% to 30%. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball. More specifically, the distance b of the crown projecting portion in the face-to-back direction is preferably 15 to 30 mm and more preferably 20 to 25 mm.

The thickness of the crown projecting portion preferably gradually decreases toward the back. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball.

In this case, the thickness of the face-side end portion of the crown projecting portion is preferably 1.5 to 3.0 mm and more preferably 1.7 to 2.7 mm, and that of the back-side end portion of the crown projecting portion is preferably 0.5 to 1.2 mm and more preferably 0.6 to 0.8 mm. This produces an effect of more easily flexing the face portion to further improve the launch angle and initial velocity of a struck ball, thereby further increasing the flight distance of the ball.

Although a method of manufacturing a golf club head according to the present invention is not particularly limited, a golf club head can be manufactured by, for example, sealing, with a face member, a face opening portion in a head body which includes the face opening portion and a crown opening portion in the portion of a crown portion in which a crown projecting portion is to be formed, and sealing the crown opening portion with a crown projecting portion forming member. In this case, although neither a material nor shaping method for the head body is particularly limited, titanium, a titanium alloy, stainless steel, or an amorphous alloy, for example, can be used as the material, and the casting method can be used as the shaping method. In the present invention, when the crown portion of the head body has a complex shape due to the presence of the crown projecting portion, at least the crown portion is preferably manufactured by the casting method. Although neither a material nor shaping method for the face member is particularly limited either, titanium, a titanium alloy, stainless steel, or an amorphous alloy, for example, can be used as the material, and the forging method, the press forming method of pressing a plate material, or the die casting method is preferable as the shaping method.

Although a method of joining the head body and the face member and crown projecting portion forming member is not particularly limited, these members are preferably joined by plasma welding, laser welding, or electron beam welding and especially by plasma welding from the viewpoint of, for example, finishing the joined portion with a good appearance and improving the weight precision of the golf club head. In this case, a known plasma welding technique of fusing a material to be welded using high-temperature energy produced by a plasma arc, and solidifying it again, thereby performing welding can be used for plasma welding. A known laser welding technique which uses a gas laser such as a CO laser or a CO₂ laser, or a solid-state laser such as a YAG laser can be used for laser welding. A known electron beam welding technique which uses an appropriately output electron beam can be used for electron beam welding.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Applications No. 2010-273594, filed Dec. 8, 2010, and No. 2010-273595, Dec. 8, 2010, which are hereby incorporated by reference herein in their entirety.

Claims

1. A hollow golf club head comprising a face portion, a crown portion, a sole portion, a side portion, and a hosel portion, wherein

a crown projecting portion in which the crown portion partly projects upward is formed at a position including a face center in a face-side region of the crown portion, and

a thickness of the crown projecting portion gradually decreases toward a back.

2. The head according to claim 1, wherein a face-side end portion of the crown projecting portion is continuous with an upper edge portion of the face portion.

3. The head according to claim 1, wherein a thickness of a face-side end portion of the crown projecting portion is 1.5 to 3.0 mm, and a thickness of a back-side end portion is 0.5 to 1.2 mm.

4. The head according to claim 1, wherein a projection height of a back-side end portion of the crown projecting portion from a crown surface is 1 to 4 mm.

5. The head according to claim 1, wherein a ratio [(a/A)×100%] of a distance a of the crown projecting portion in a toe-to-heel direction to a distance A of the crown portion in the toe-to-heel direction is 20% to 60%.

6. The head according to claim 1, wherein a ratio [(b/B)×100%] of a distance b of the crown projecting portion in a face-to-back direction to a distance B of the crown portion in the face-to-back direction is 10% to 40%.

7. A hollow golf club head comprising a face portion, a crown portion, a sole portion, a side portion, and a hosel portion, wherein

a crown projecting portion in which the crown portion partly projects upward is provided at a position including a face center in a face-side region of the crown portion, and

the crown projecting portion is formed using a material having a Young's modulus lower than a Young's modulus of a portion other than the crown projecting portion in the crown portion.

8. The head according to claim 7, wherein the portion other than the crown projecting portion in the crown portion is formed using a material having a Young's modulus of not less than 100 GPa, and the crown projecting portion is formed using a material having a Young's modulus of 65 to 95 GPa.

9. The head according to claim 7, wherein a difference between the Young's modulus of the material which forms the portion other than the crown projecting portion in the crown portion and the Young's modulus of the material which forms the crown projecting portion is 15 to 50 GPa.

10. The head according to claim 7, wherein the portion other than the crown projecting portion in the crown portion is formed using a first high-strength titanium alloy, and the crown projecting portion is formed using a second high-strength titanium alloy having a Young's modulus lower than a Young's modulus of the first high-intensity titanium alloy.

11. The head according to claim 7, wherein a face-side end portion of the crown projecting portion is continuous with an upper edge portion of the face portion.

12. The head according to claim 7, wherein a projection height of a back-side end portion of the crown projecting portion from a crown surface is 1 to 4 mm.

13. The head according to claim 7, wherein a ratio [(a/A)×100%] of a distance a of the crown projecting portion in a toe-to-heel direction to a distance A of the crown portion in the toe-to-heel direction is 20% to 60%.

14. The head according to claim 7, wherein a ratio [(b/B)×100%] of a distance b of the crown projecting portion in a face-to-back direction to a distance B of the crown portion in the face-to-back direction is 10% to 40%.

15. The head according to claim 7, wherein a thickness of the crown projecting portion gradually decreases toward a back.

16. The head according to claim 15, wherein a thickness of a face-side end portion of the crown projecting portion is 1.5 to 3.0 mm, and a thickness of a back-side end portion is 0.5 to 1.2 mm.