Golf club head

A golf club head according to the present invention includes a head body and at least one cover member attached to the head body and having a specific gravity smaller than the head body. The head body has an internal space, and includes at least one opening and in communication with the internal space, and at least one bridge portion having a traverse portion that traverses at least the opening and extending along an inner wall surface of the head body. The opening is closed by the cover member, a height of the bridge portion from the inner wall surface of the head body changes in a direction in which the bridge portion extends.

TECHNICAL FIELD

The present invention relates to a golf club head.

BACKGROUND ART

Wood-type golf club heads have undergone many refinements heretofore, and various proposals have been made in order to increase the flexibility of center of gravity design. For example, in JP 3762906B, an opening is formed in the head, and a lightweight cover member formed with fiber-reinforced plastic or the like is arranged so as to close this opening. Since the weight of the region to which the cover member is attached is thereby reduced, the saved weight can be distributed to other regions. Thus, the flexibility of center of gravity design improves.

JP 3762906B is an example of related art.

However, there is a problem that the rigidity of the head decreases when the opening is formed. The present invention has been made in order to solve the above problem, and an object thereof is to provide a golf club head that is able to suppress a decrease in the rigidity of the head due to formation of an opening.

SUMMARY OF THE INVENTION

A golf club head according to the present invention includes a head body having a face portion, a crown portion and a sole portion, and at least one cover member attached to the head body and having a specific gravity smaller than the head body, the head body having an internal space surrounded by the face portion, the crown portion and the sole portion, and including at least one opening formed in at least one of the crown portion and the sole portion and in communication with the internal space, and at least one bridge portion having a traverse portion that traverses at least the opening and extending along an inner wall surface of the head body, the opening being closed by the cover member from an outer side of the head body, the bridge portion including a joining surface that contacts the cover member, and a height of the bridge portion from the inner wall surface of the head body changing in a direction in which the bridge portion extends.

In the golf club head, the bridge portion can extend in a toe-heel direction to a vicinity of a toe-side edge portion of the sole portion, and the height of the bridge portion can be formed to become lower proceeding toward the toe-side edge portion of the sole portion.

In the golf club head, the bridge portion can extend in the toe-heel direction to a vicinity of a heel-side edge portion of the sole portion, and the height of the bridge portion can be formed to become lower proceeding toward the heel-side edge portion of the sole portion.

In the golf club head, an installation portion on which a peripheral portion of the cover member is arranged can be formed on a peripheral portion of the opening, a step can be formed at a boundary between an outer edge of the installation portion and an outer surface of the head body, and the golf club head can be constituted such that the peripheral portion of the cover member arranged on the installation portion is substantially flush with the outer surface of the head body.

In the golf club head, a first thin portion having a small thickness can be formed in part of the installation portion.

In the golf club head, in the head body, a second thin portion having a smaller thickness than the installation portion can be formed at least partially around the installation portion.

In the golf club head, a thick portion having a larger thickness than the second thin portion can be formed at least partially around the second thin portion.

In the golf club head, the thick portion can be formed on the toe side and the heel side, sandwiching the opening.

In the golf club head, a configuration can be adopted in which one of the bridge portions extends in the toe-heel direction, the opening is partitioned by the bridge portion that extends in the toe-heel direction into a first opening on a face side and a second opening on a back side, and the first opening has a smaller area than the second opening.

In the golf club head, the opening can be formed on the toe side in the toe-heel direction.

In the golf club head, the opening can be formed in the sole portion.

With the golf club head according to the present invention, a decrease in the rigidity of the head due to formation of an opening can be prevented.

EMBODIMENTS OF THE INVENTION

Hereinafter, an embodiment of a golf club head according to the present invention will be described, with reference to the drawings.

1. Overview of Golf Club Head

FIG. 1is a perspective view of this golf club head,FIG. 2is a plan view of the head in a reference state, andFIG. 3is a plan view of the golf club head in the reference state viewed from below. As shown inFIGS. 1 to 3, this golf club head (hereinafter, may be referred to simply as “head”)100is a wood-type golf club head having a head body10that is a hollow structure having an internal space whose wall surface is formed by a face portion1, a crown portion2, a sole portion3and a hosel portion4, and a cover member5attached to the sole portion3of this head body10. Specifically, the present invention can be applied to golf club heads such as utilities (hybrids), fairway woods and drivers.

The face portion1has a face surface that is the surface that hits the ball, and the crown portion2adjoins the face portion1and constitutes the upper surface of the head body10. The sole portion3mainly constitutes the bottom surface of the head body10, and constitutes the outer peripheral surface of the head body10other than the face portion1and the crown portion2. That is, in addition to the bottom surface of the head body10, the region extending from the toe side of the face portion1around the back side of the head to the heel side of the face portion1is also part of the sole portion3. Furthermore, the hosel portion4is a region that is provided adjoining the heel side of the crown portion2, and has an insertion hole41into which a shaft (illustration omitted) of the golf club is inserted, and that is formed in a cylindrical shape extending inside the head. A center axis line Z of this insertion hole41coincides with the axis line of the shaft.

As shown inFIG. 3, a first opening31and a second opening32are formed in the sole portion3as will be discussed later, and the cover member5is attached with an adhesive or the like so as to close these openings31and32.

Here, the reference state when setting the golf club head100on the ground will be described. First, as shown inFIG. 2, a state where the above center axis line Z is contained in a plane P1that is perpendicular to the ground and the head is placed on the ground at a predetermined lie angle and real loft angle is prescribed as the reference state. The plane P1will be referred to as a reference perpendicular plane. Also, as shown inFIG. 2, the direction of the line of intersection between the reference perpendicular plane P1and the ground will be referred to as a toe-heel direction, and the direction that is perpendicular to this toe-heel direction and parallel to the ground will be referred to as a face-back direction. Also, the direction that is orthogonal to the toe-heel direction and the face-back direction may be referred to as an up-down direction.

In the present embodiment, the boundary between the face portion1and the crown portion2and between the face portion1and the sole portion3can be defined as follows. That is, in the case where a ridgeline is formed therebetween, this ridgeline will be the boundary. On the other hand, in the case where a clear ridgeline is not formed, then in each of cross-sections E1, E2, E3and so forth that contain a straight line N connecting a head center of gravity G and a sweet spot SS, as shown inFIG. 4A, a position Pe at which a curvature radius r of a contour line Lf of the face outer surface first reaches 200 mm in a direction toward the outer side of the face from the sweet spot side, as shown inFIG. 4B, will be the periphery of the face portion1, and this periphery is defined as the boundary with the crown portion2or the sole portion3. Note that the sweet spot SS is the point of intersection between the normal (straight line N) of the face surface that passes through the head center of gravity G and this face surface.

Also, in the present embodiment, the boundary between the crown portion2and the sole portion3can be defined as follows. That is, in the case where a ridgeline is formed between the crown portion2and the sole portion3, this ridgeline will be the boundary. On the other hand, in the case where a clear ridgeline is not formed therebetween, the contour when the head is set in the reference state and viewed from directly above the center of gravity of the head10will be the boundary.

The head body10can, for example, be formed with a titanium alloy (Ti-6Al-4V, Ti-8Al-1Mo-1V, etc.) having a specific gravity of substantially about 4.3 to 4.5. Apart from a titanium alloy, the head can also be formed using one or two or more materials selected from stainless steel, maraging steel, an aluminum alloy, a magnesium alloy and an amorphous alloy, for example.

On the other hand, the cover member5is formed with a material whose specific gravity is smaller than the head body10, and can, for example, be formed with a material whose specific gravity is 0.9 to 3.0. As such a material, plastics such as polyetheretherketone (PEEK) or polycarbonate (PC), fiber-reinforced plastic, an Mg alloy, an aluminum alloy or the like can be employed, for example. As another viewpoint, the cover member5can, for example, also be formed with a material whose Young's modulus is smaller than the head body10. In this case, Young's modulus of the cover member5can be set from 4 MPa to 125 GPa, and Young's modulus of the head body10can be set from 100 GPa to 130 GPa.

The volume of this golf club head100is desirably from 90 cm3to 470 cm3inclusive, for example.

2. Structure of Outer Surface of Sole Portion

Next, the structure of the outer surface of the sole portion3will be described, with reference also toFIG. 5.FIG. 5is a plan view showing a state in which the cover member is removed from the sole portion.

As shown inFIG. 3mentioned above, a square-shaped cover member5is attached to the sole portion3, and, as shown inFIG. 5, in the region in which the cover member5is attached, a triangular first opening31and a square-shaped second opening32that is larger than the first opening31are formed further on the toe side than the center of the sole portion3in the toe-heel direction, and these openings31and32are in communication with the internal space of the head body10. Also, a first installation portion33and a second installation portion (first thin portion)34that the cover member5abuts against are formed around these openings31and32, and a partition portion (traverse portion)35that the cover member5abuts against is formed between the two openings31and32. The cover member5is fixed by an adhesive or the like to these portions.

The first installation portion33is slightly recessed from the outer surface of the sole portion3, and is formed in a square frame shape so as to surround the two openings31and32. That is, a step is formed at the boundary between the outer edge of the first installation portion33and the outer surface of the sole portion3. Here, for convenience of description, the face-side outer edge, the toe-side outer edge, the back-side outer edge and the heel-side outer edge of the first installation portion31will be respectively referred to as a first edge portion331, a second edge portion332, a third edge portion333and a fourth edge portion334. The first edge portion331is slightly away from the face portion1, and extends generally parallel to the face portion1. The second edge portion332is in proximity to the toe-side edge portion of the sole portion3and extends in an arc along that edge portion. The third edge portion333is formed as a straight line that bends part way along, and the heel-side end portion is located further on the heel side than the heel-side end portion of the first edge portion331. The fourth edge portion334is formed so as to extend on the toe side proceeding toward the face side, while extending in the face-back direction.

The second installation portion34is formed in a square shape extending from the first installation portion33towards the second edge portion332, and is formed to be thinner than the first installation portion33, as will be discussed later. Furthermore, the partition portion35extends so as to connect the second edge portion332and the fourth edge portion334of the first installation portion33, and the two openings31and32are partitioned by this partition portion35. The partition portion35is formed so as to extend slightly on the face side proceeding toward the toe side, while extending in the toe-heel direction. Also, a rib351is formed on the inner surface of the partition portion35, that is, on the surface of the partition portion35on the internal space side, as will be discussed later.

Note that, on the outer surface side of the head body10, the first installation portion33, the second installation portion34and the partition portion35are formed to be flush without any step, and the cover member5is thereby firmly fixed. The height of the step between the first installation portion33and the outer surface of the sole portion3is generally the same as the thickness of the cover member5. Accordingly, the outer surface of the cover member5will be generally flush with the outer surface of the sole portion3, when the cover member5is attached to the sole portion3.

Also, in the sole portion3, a fixing hole38for attaching a weight member (illustration omitted) is formed further on the back side than the cover member5. A female thread (illustration omitted) for screwing in a male thread attached to the weight member is formed in the inner wall surface of the fixing hole38.

3. Structure of Inner Surface of Sole Portion

Next, the structure of the inner surface of the sole portion3will be described, with reference also toFIGS. 6 to 8.FIG. 6is a plan view of an inner surface viewed through the sole portion from a lower surface side,FIG. 7is a perspective view showing the internal space of the head with the head partially cut away, andFIG. 8is a cross-sectional view along line A-A inFIG. 5.

As shown inFIGS. 6 to 8, on the inner surface of the sole portion3, the first installation portion33is a region that mainly supports the cover member5, and thus the thickness thereof can, for example, be set from 0.4 to 1.0 mm. The partition portion35is also the same thickness as the first installation portion33. On the other hand, the second installation portion34is a region that supports the cover member5, so as to complement the first installation portion33, and is thus formed to be thinner than the first installation portion33.

Also, as shown inFIG. 6, in the sole portion3, a first area371(light gray colored portion: second thin portion) formed in an L-shape so as to surround the third edge portion333and the fourth edge portion334of the first installation portion33, and, furthermore, a second area372(dark gray colored portion: thick portion) formed so as to surround this first area371and the second edge portion332of the first installation portion33are provided in an area further on the outer side than the first installation portion33. The first area371is arranged generally in the vicinity of the middle in the toe-heel direction, and part of the second area372is arranged further on the heel side than the first area371. Also, since part of the second area372is arranged further on the toe side than the openings31and32, the second area372is arranged on both sides in the toe-heel direction across the openings31and32.

As shown inFIG. 8, the first area371is formed to be thinner than the first installation portion33, and the second area372is formed to be thicker than the first area371but thinner than the first installation portion33. Furthermore, a rear area373is formed around the fixing hole38further on the back side than the second area372. This rear area373is formed so as to follow the edge portion of the sole portion3on the back side, and includes a region whose thickness in the sole portion3is equivalent to or greater than the first installation portion33.

As shown inFIGS. 6 and 7, the rib351is formed on the inner surface of the sole portion3. This rib351passes through the inner surface of the abovementioned partition portion35, and further extends on the toe side and the heel side. That is, the toe-side end portion of the rib351extends to the second edge portion332of the first installation portion33, and the heel-side end portion extends to the heel-side edge portion of the sole portion3. Accordingly, the rib351extends so as to approach the back side proceeding toward the heel side, rather than extending parallel to the face portion1.

The width of the rib351is narrower than the partition portion35, and can, for example, be set from 0.5 to 1.5 mm. Also, the height of the rib351can, for example, be set to a height of 1.0 to 7.0 mm from the first installation portion33and the partition portion35. As shown inFIG. 7, the height of the rib351becomes lower proceeding toward the toe side, and the height from the inner surface of the sole portion is zero at both end portions thereof. Also, from the viewpoint of the hitting sound discussed later, the large rib351is preferably formed near the face portion1, and is, for example, preferably formed in an area within 50 percent of the length of the head100in the face-back direction from the face portion1.

4. Assembly Structure of Golf Club Head

The golf club head100according to the present embodiment can be configured to have various assembly structures. For example, a structure can be adopted in which an opening is formed in the face portion1, and a face member is fitted into this opening and fixed by welding. The face member can, for example, be manufactured by a method such as forging, plate pressing or casting. On the other hand, portions other than the face member can be manufactured by casting such as a well-known lost wax precision casting process.

Alternatively, a so-called cup face structure can also be adopted in which a cup-shaped face member provided with the face portion1and a peripheral portion that projects from a periphery of the face portion1are formed, and this cup-shaped face member is attached to an opening formed on the face side of the crown portion2and the sole portion3. In this case, the face member can similarly be manufactured by a method such as forging, plate pressing or casting, as mentioned above, and other portions can be formed by a precision casting process such as the above.

Also, the openings31and32can be formed by cutting the sole portion3with a laser or the like, after casting the head or after attaching the face member as mentioned above. Thereafter, the head100is completed when the cover member5is fixed with an adhesive to the two installation portions33and34and the partition portion35.

According to the above embodiment, the following effects can be obtained.

(1) Since the openings31and32are formed in the sole portion3, and the cover member5having a low specific gravity is attached so as to close these openings31and32, the weight of the sole portion3can be reduced. Since that saved weight can be distributed to other regions, the flexibility of center of gravity design of the head100can be improved. In particular, since the openings31and32are formed on the toe side, and, furthermore, the thickness of the first area371surrounding the first installation portion33is made smaller, the weight on the toe side can be reduced. Also, the height of the rib351becomes lower proceeding toward the toe side, contributing to the weight reduction on the toe side. On the other hand, since the second area372having a large thickness is formed on the heel side, the weight on the heel side can be increased. Accordingly, the head readily returns to square during the swing, and slicing can be reduced.

Note that since the second area372is formed on both the toe side and the heel side, sandwiching the openings31and32, the heavy portions are formed in the vicinity of the toe-side and heel-side end portions of the sole portion3. Accordingly, the moment of inertia of the right and left of the head100can be increased.

(2) Since the rear area373having a large thickness is formed on the back side of the sole portion3, the center of gravity depth of the head100can be increased. Since the loft angle at the time of impact thereby increases, the launch angle can be increased.

(3) Since the rib351is formed so as to traverse between the openings31and32, a decrease in the rigidity of the head caused by the openings31and32can be suppressed. On the other hand, since the height of the rib351becomes smaller proceeding toward the toe side, the increase in weight caused by the rib351can be suppressed. As a result, the flexibility of weight distribution can be prevented from being impaired. Also, since the sole portion3curves such that the toe side gradually becomes higher, the rib351becomes smaller proceeding toward the toe side, enabling the height of the rib351from the lowest point of the sole portion3to be kept at a low position on the toe side. Accordingly, an increase in the center of gravity of the head due to the weight of the rib351can be suppressed, while obtaining the effects of reinforcement by the rib351.

Also, vibration occurs in the sole portion3due to the ball hitting the face portion1, and a plurality of antinodes of this vibration may occur in the toe-heel direction of the sole portion3. When the rib351extending in the toe-heel direction is formed, so as to pass through the portion where such antinodes of vibration occur, the vibration can be reduced. In particular, antinodes of vibration of low frequency often occur adjacent to the face portion1, and thus by forming a rib in a position near the face portion1, as in the present embodiment, such vibration of low frequency can be suppressed, and the pitch of the hitting sound can be increased. Accordingly, vibration of desired frequencies can be suppressed by forming the rib351extending in the toe-heel direction.

(4) In the sole portion3, the first installation portion33, the second installation portion34and the partition portion35are formed as a region that contacts the cover member5. In this way, the joining strength between the head body10and the cover member5can be improved, by enlarging the area that contacts the cover member5. Also, the cover member5is further reinforced, as a result of the partition portion35on which the rib351is formed contacting the cover member5. Also, since the cover member5is generally formed with a material of lower rigidity than the head body10, vibration thereby tends to occur with a low vibration frequency when the ball is hit. Thus, a low pitched hitting sound tends to occur. In contrast, as mentioned above, when the cover member5is reinforced, vibration of low vibration frequency can be suppressed. As a result, vibration of high vibration frequency can be produced, and the hitting sound can be configured to be high pitched.

Although an embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. Also, the following variations can be combined as appropriate. For example, the following modifications can be made.

6-1. The openings31and32are not particularly limited in terms of shape, position and number, and can, for example, also be formed on the heel side or the back side. Also, in the above embodiment, two installation portions33and34and a partition portion35that the cover member5abuts against are formed, and the shape of the area that the cover member5abuts against is not particularly limited.

6-2. Also, in the above embodiment, the first installation portion33is formed so as to be recessed from the outer surface of the sole portion3, and the cover member5and the outer surface of the sole portion3are thereby formed to be flush. In contrast, for example, the cover member5can also be adhered to the outer surface of the sole portion3on the outer side of the openings31and32, without forming the first installation portion33recessed from the outer surface of the sole portion3. Although a step will thereby be formed between the cover member5and the outer surface of the sole portion3, such a mode is also possible.

6-3. The rib351need only be formed so as to pass between at least the two openings31and32. Alternatively, it can also be said that the rib351need only be formed so as to traverse one opening. Accordingly, the number and position of ribs is not particularly limited. For example, in the above embodiment, the rib351passes beyond the openings31and32and extends on the toe side and the heel side, but can also be formed only in the vicinity of where the openings31and32are traversed.

In the above embodiment, the height of the rib351becomes lower proceeding toward the toe side, but may become lower proceeding toward the heel side. Similar effects to the effects resulting from the rib351becoming lower proceeding toward the toe side can thereby be obtained. Also, the height of the rib351may change incrementally, or a configuration can also be adopted in which the height is changed by providing a step. Additionally, the height of the rib351is not particularly limited, and the portion that is lowered can be changed as appropriate according to factors such as the center of gravity design corresponding to the performance that is required. That is, weight can be arranged at a desired position by adjusting the height of the rib351.

Also, the rib351and the partition portion35of the present embodiment constitute a bridge portion of the present invention, and the portion that abuts against the cover member5in the partition portion35constitutes a joining surface of the present invention. A configuration can also be adopted in which the bridge portion is formed with only the rib351without providing the partition portion35, and the rib351abuts against the cover member5. In this case, the portion of the rib351that abuts against the cover member5corresponds to the joining surface of the present invention. Alternatively, the bridge portion can also be formed with only the partition portion35.

6-4. The thickness of the sole portion3is not limited to that shown in the above embodiment, and various thickness distributions can be configured. For example, the first area371need only be formed at least partially around the openings31and32or the first installation portion33. The shape of the second area372is also not particularly limited.

6-5. In the above embodiment, the openings31and32are formed in the sole portion3, but can also be formed in the crown portion2. Since the crown portion2is, however, generally smaller in thickness compared with the sole portion3, the weight reduction effects obtained by forming the openings31and32is considered to be higher when forming the openings in the sole portion3. Also, in the case of forming the openings in the crown portion2, the position and number of openings, the mode for installing the cover member5and the mode of the bridge can be changed as appropriate similarly to the case of forming openings and a bridge in the sole portion3. Alternatively, openings and a bridge portion can also be formed in both the sole portion3and the crown portion2.

LIST OF REFERENCE NUMERALS