MANUFACTURING METHOD AND GOLF CLUB HEAD

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a golf club head.

Description of the Related Art

To improve the performance of a golf club head, various structures have been proposed. For example, U.S. Pat. No. 6,558,271 discloses a golf club head that has a hollow structure incorporating a skeleton so as to improve the degree of freedom for the position of center of gravity and the like. For example, each of U.S. Pat. Nos. 7,140,977 and 8,602,912 and Japanese Patent No. 5438124 discloses a golf club head having a structure that reinforces the central portion of the face portion. Each of Japanese Patent No. 4608437 and 4608426 discloses a golf club head that includes an interchangeable part so as to allow a user to select desired characteristics. Each of Japanese Patent No. 4608437 and 4608426 discloses an interchangeable part that promotes attenuation of vibration in the face portion at impact. Japanese Patent Laid-Open No. 2012-525214 discloses a golf club head having a structure that reinforces the central portion of the face portion.

In a hollow golf club head represented by a driver head, the spring effect of the face portion has influence on distance performance. On the other hand, R&A and USGA regulate the spring effect of the face portion of the driver head to be the CT value of 257 μs or less (coefficient of restitution of 0.83 or less). Although a golf club head that has a spring effect close to such a regulation value is advantageous in terms of distance performance, a manufacturing error can occur in the manufacture of the golf club head. Hence, if a golf club head is designed to have a spring effect which is close to the regulation value as possible, an individual golf club head that exceeds the regulation value may be manufactured. If the golf club head is designed with a margin to the regulation value, an individual golf club head that is far below the regulation value, and thus inferior in distance performance, may be manufactured.

SUMMARY OF THE INVENTION

It is an object of the present invention to reduce individual differences in the spring effect.

According to an aspect of the present invention, there is provided a manufacturing method comprising: a measurement step of measuring a spring effect of a face portion of a hollow golf club head; and a selection step of selecting, based on a measurement result of the measurement step, an adjustment device, out of a plurality of adjustment devices, to be attached to an attachment portion of the golf club head, wherein the plurality of adjustment devices have different degrees of suppression to the spring effect of the face portion from each other.

According to another aspect of the present invention, there is provided a hollow golf club head comprising: a head body; a support member selected out of a plurality of support members, each of which is attachable to an attachment portion provided in the head body; and an abutment member attached to the attachment portion through the support member and abuts against a rear surface of a face portion of the head body, wherein the plurality of support members support the abutment member so that positions where the abutment members abut against the rear surfaces are different from each other.

According to still another aspect of the present invention, there is provided a hollow golf club head comprising: a head body; and an abutment member selected out of a plurality of abutment members, each of which is attachable to an attachment portion provided in the head body, wherein each of the plurality of abutment members has an abutment portion that abut against rear surface of face portion, and the plurality of abutment members include a plurality of abutment members having different abutment portion shapes from each other.

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. 1A is a perspective view of a golf club head according to an embodiment of the present invention;

FIG. 1B is a view showing the golf club head in FIG. 1A viewed from the side of a sole portion;

FIG. 2A is a sectional view taken along a line I-I in FIG. 1A;

FIGS. 2B to 2F are views showing examples of an adjustment device;

FIG. 3 is a flowchart of a manufacturing method according to the embodiment of the present invention;

FIGS. 4A to 4C are explanatory views of other examples;

FIGS. 5A and 5B are explanatory views of other examples; and

FIGS. 6A to 6C are explanatory views of other examples.

DESCRIPTION OF THE EMBODIMENTS
First Embodiment

FIG. 1A is a perspective view of a golf club head 1 according to an embodiment of the present invention. FIG. 1B is a view of the golf club head 1 viewed from the side of a sole portion 13. The golf club head 1 includes a head body 10 and an adjustment device 18.

The head body 10 is hollow and has peripheral walls formed from a face portion 11, a crown portion 12, the sole portion 13, and a side portion 14. The surface (front surface) of the face portion 11 forms a face (striking face). A bulge and a roll can be formed on the face. The crown portion 12 forms the upper portion of the golf club head 1. The sole portion 13 forms the bottom portion of the golf club head 1. The side portion 14 forms the portion between the sole portion 13 and the crown portion 12. The head body 10 includes a hosel portion 15 to which a shaft is attached.

An arrow d1 in FIG. 1A indicates the face-back direction, and an arrow d2 indicates the toe-heel direction. The face-back direction normally corresponds to a target line direction (target direction of a shot). The toe-heel direction is the direction in which the toe-side end and the heel-side end of the sole portion 13 are connected. The vertical direction of the face portion 11 is defined based on the golf club head 1 grounded in accordance with a predetermined lie angle. In this embodiment, the vertical direction is the direction of sole portion 13—crown portion 12.

The golf club head 1 is a golf club head for a driver. However, the present invention is applicable to golf club heads of other types such as wood-type golf club heads including a fairway wood other than a driver.

The head body 10 can be made of a metal material. Examples of the metal material are a titanium-based metal (for example, titanium alloy 6Al-4V-Ti), stainless steel, and a copper alloy such as beryllium copper.

The head body 10 can be assembled by joining a plurality of parts. For example, the golf club head 10 can be formed from a main body member and a face member. The main body member includes the crown portion 12, the sole portion 13, the side portion 14, a peripheral portion of the face portion 11 and an opening formed at a part of the portion corresponding to the face portion 11. The face member is joined to the opening of the main body member.

The head body 10 includes an attachment portion 16. In this embodiment, the attachment portion 16 is disposed in the sole portion 13. More specifically, the sole portion 13 includes a concave portion 13a that is recessed with respect to the periphery, and the attachment portion 16 is formed in the wall portion of the concave portion 13a and located inside the head body 10. In addition, the attachment portion 16 is located at the central portion of the sole portion 13 concerning the direction d2, and disposed at a position close to the side of the face portion 11 concerning the direction d1.

In the embodiment, the attachment portion 16 is a threaded hole. The attachment portion 16 is formed such that a center line d3 crosses the face portion 11. The adjustment device 18 is attachable to the attachment portion 16. Although the attachment portion 16 is located inside the golf club head 10, the concave portion 13a makes it relatively easy to attach the adjustment device 18.

In the embodiment, the adjustment device 18 forms an abutment member that abuts against the rear surface of the face portion 11. More particularly, in the embodiment, the adjustment device 18 is a member integrally including a screw shaft 18a, a head portion 18b, and a distal end portion 18c which faces the rear surface of the face portion 11. The head portion 18b has a hole that has a closed bottom and engages with a tool such as a hexagonal wrench. The screw shaft 18a has a shaft diameter and a screw thread pitch to threadably engage with the attachment portion 16. The distal end portion 18c forms an abutment portion that abuts against the rear surface (the internal space side surface of the head body 10) of the face portion 11. FIG. 2A is a sectional view taken along a line I-I in FIG. 1A and shows the abutment manner of the distal end portion 18c against the rear surface of the face portion 11.

Deformation of the face portion 11 is restricted when the distal end portion 18c abuts against the face portion 11 than when it does not. That is, the spring effect at impact of the face portion 11 is suppressed. The distal end portion 18c may be in contact so as not to press the rear surface of the face portion 11 or so as to press the rear surface to the face side in the natural state.

The abutment manner of the distal end portion 18c against the face portion 11 has an influence on the degree of restriction to deformation of the face portion 11. For example, the larger the abutment area of the distal end portion 18c that abuts against the rear surface of the face portion 11, the higher the degree of restriction to the face portion 11. Hence, a plurality of adjustment devices 18 having different degrees of spring effect suppression to the face portion 11 from each other are prepared, and an adjustment device 18 corresponding to the individual head body 10 is selected to adjust the spring effect of the face portion 11 and reduce individual differences.

FIGS. 2B to 2F illustrate five types of adjustment devices 18 attachable to the attachment portion 16, respectively. The adjustment devices 18 of FIGS. 2B to 2F have the same total length and the same structure of the screw shaft 18a and the head portion 18b, but the distal end portions 18c have different shapes.

Although the distal end portion 18c is tapered in each of the adjustment devices 18 in FIGS. 2B to 2D, the areas of the respective distal end surfaces are different. Among the examples, the example of FIG. 2C has the largest area of distal end surface, and the example of FIG. 2D has the smallest area of distal end surface. The distal end surfaces of FIGS. 2B to 2D have circular shapes. The distal end portion 18c of the adjustment device 18 of FIG. 2E has a spherical shape. The distal end portion 18c of FIG. 2F has a columnar shape and has the largest area of distal end surface out of the adjustment devices 18 of FIGS. 2B to 2F. Assuming that the abutment area of the distal end portion 18c against the rear surface of the face portion 11 is the same as the area of distal end surface of the adjustment device 18, the adjustment device 18 of FIG. 2F has the highest degree of restriction to deformation of the face portion 11.

Here, it should be noted that R&A and USGA regulate the spring effect of a face portion to the CT value of 257 μs or less (0.83 or less in coefficient of restitution). Although a golf club head which has a spring effect close to such a regulation value is advantageous in terms of distance performance, a manufacturing error can occur in the manufacture of the golf club head. Hence, the manufacturing error can be absorbed by selecting the type of the adjustment device 18, and the spring effect can be brought closer to a CT value intended by a designer. FIG. 3 is a flowchart showing an example of a manufacturing method of a plurality of golf club heads 1 that are to be shipped to the market.

In step S1, the golf club head 1 is designed. A prototype may be manufactured and an inspection operation may be performed as needed. In terms of the design of the golf club head 1, the golf club head can be designed so that the CT value of the face portion 11 of the head body 10 will be 257 μs or more. Alternatively, the CT value of the head main body 10 can actually be 257 μs or more. By designing and manufacturing the head main body to have a CT value as close to the regulation value as possible or to exceed the regulation value and then decreasing the CT value to not more than the regulation value by selecting the adjustment device 18, a golf club head 1 that has a CT value close to the regulation value can be manufactured.

In step S2, the head body 10 of the golf club head 1 designed in step S1 is mass-produced. The adjustment device 18 is also mass-produced in parallel. All the components of the golf club head 1 are prepared in step S2.

In step S3, the spring effect of the face portion 11 of each head body 10 which was mass-produced in step S2 is measured. All or some of the mass-produced head bodies 10 can be set as measurement targets. If only some of the mass-produced head bodies are to be measurement targets, the head bodies can be divided into groups based on the thickness of each face portion 11 or the like so that one or a plurality of head bodies 10 can be set as measurement targets on a group basis. The obtained result can be regarded as the measurement result of all of the mass-produced head bodies in the group, and an adjustment device 18 can be commonly selected. As a method of measuring the spring effect, for example, the CT value can be measured by a dedicated CT pendulum testing device that is in compliance with the pendulum test of R&G and USGA.

In step S4, based on the measurement results of step S3, an adjustment device 18 to be attached to each attachment portion 16 is selected out of the plurality of adjustment devices 18 and attached to the attachment portion 16. Although the plurality of adjustment devices 18 have different degrees of suppression to the spring effect of the face portion 11 (as already described above), it is sufficient to have at least 2 types of selectable adjustment devices 18.

In step S5, the spring effect of the face portion 11 of each golf club head 1 attached with the adjustment device 18 is measured again. The measurement method is the same as that in step S3.

In step S6, it is determined whether each remeasurement result of step S5 is within a predetermined range. As the predetermined range, an upper limit and the lower limit of the CT value can be set at 257 μs and 250 μs, respectively. If a measurement error is expected, for example, the upper limit and the lower limit of the CT value can be set at 255 μs and 248 μs, respectively. In addition, if the adjustment device 18 is to be selected on a group basis as described above, the upper limit and the lower limit of the CT value can be set to 250 μs and 240 μs, respectively, in consideration of individual differences within the group.

If the remeasurement result is not within a predetermined range, the process returns to step S4, and the adjustment device 18 is changed. For example, if the CT value has exceeded the upper limit, an adjustment device 18 having a higher degree of restriction to the face portion 11 is selected and attached. On the other hand, if the CT value is less than the lower limit, an adjustment device 18 having a lower degree of restriction to the face portion 11 is selected and attached.

If the remeasurement result is within the predetermined range, final processes (ornamentation processing, and the like) are performed as needed, and the manufacture of the golf club heads 1 is completed.

In this manner, according to the first embodiment, the individual differences in the spring effect of the face portions 11 can be reduced, and the golf club heads 1 each having a CT value close to the regulation value can be stably manufactured. The adjustment of the spring effect of the face portion 11 can be performed based on the measurement of the spring effect and the selection of the adjustment device 18 based on the measurement result, so the spring effect can be adjusted relatively easily.

Second Embodiment

As a result of the measurement in step S3, the CT value of a face portion 11 of a head body 10 may already be within a predetermined range. In such a case, there is no need to attach an adjustment device 18 in terms of the spring effect. However, the position of the center of gravity, the weight of the head, and the like may differ greatly in some cases unless the adjustment device 18 is attached, and this may influence the performance of a golf club head 1. Hence, an adjustment device 18 which has no influence on the spring effect can be included among the plurality of adjustment devices 18 that are selectable in step S4.

FIGS. 4A and 4B show such an example. The adjustment device 18 in FIGS. 4A and 4B is formed with a short distal end portion 18c, and, as shown in FIG. 4A, the distal end portion 18c is spaced apart from the rear surface of the face portion 11 in the natural state. Hence, it becomes a state in which the deformation of the face portion 11 at impact is not restricted or the distal end portion 18c abuts only slightly against the face portion 11, and there is almost no influence on the spring effect of the face portion 11. On the other hand, a screw shaft 18a and a head portion 18b are the same as those in other adjustment devices 18, thereby avoiding a case in which the position of the center of gravity, the weight of the head, and the like of the golf club head 1 differ greatly.

Third Embodiment

In the first embodiment, the adjustment device 18 has an arrangement that integrally includes the screw shaft 18a, the head portion 18b, and the distal end portion 18c. However, it may be an arrangement in which a distal end portion 18c is selectable. FIG. 4C shows an example. In the example of FIG. 4C, an engagement portion 18e is formed on the distal end surface of a screw shaft 18a, and each distal end portion 18c has an engagement portion 18d which engages with the engagement portion 18e. In the example of FIG. 4C, the engagement portion 18e is a hole that has a closed bottom, and each engagement portion 18d is a shaft to be inserted to this hole. The engagement portion 18e and the engagement portion 18d can have an arrangement in which they fit each other or an arrangement in which they are joined by an adhesive or the like.

Fourth Embodiment

In the first embodiment, the distal end portions 18c of the plurality of adjustment devices 18 have been exemplified as having different shapes. However, at least parts of the materials of the adjustment devices 18 may be different. By using different materials, the deformation of each adjustment device 18 to the deformation against the deformation of a face portion 11 at impact will be different, and the degree of suppression to the spring effect of the face portion 11 can be made different. In this case, the plurality of adjustment devices 18 can have different shapes, all have the same shape, or have a mixture of same and different shapes of distal end portions 18c.

As the material, for example, resin, rubber, or the like may be used in addition to a metal such as stainless steel or aluminum. If the rigidity of the material is high, the degree of suppression to the spring effect becomes relatively high, and if the rigidity of the material is low, the degree of suppression to the spring effect becomes relatively low.

The portion using a different material can be all or a part of each adjustment device 18. If only a part of the adjustment device 18 is to use a different material, for example, the distal end portion 18c can be configured to be selectable as in the third embodiment, and the plurality of distal end portions 18c can be made of different materials.

Fifth Embodiment

In the first embodiment, the plurality of adjustment devices 18 have been exemplified as having different shapes of distal end portions 18c. However, the position at which each device abuts against the rear surface of a face portion 11 can be different. FIGS. 5A and 5B show an example. FIG. 5A shows an exploded view, and FIG. 5B shows an assembly view.

An adjustment device 18 of the fifth embodiment is formed by an abutment member 181 and a support member 182. The abutment member 181 has the same arrangement as the adjustment device 18 of the first embodiment and is a member that integrally includes a screw shaft 181a, a head portion 181b, and a distal end portion 181c facing the rear surface of the face portion 11. The abutment member 181 is attached to an attachment portion 16 through the support member 182, and the distal end portion 18c forms the abutment portion that abuts against the rear surface of the face portion 11.

The support member 182 is an angle adjustment member that adjusts the direction of the abutment member 181. The support member 182 includes a threaded hole 182a that threadably engages with the screw shaft 18a. The structure fixing the support member 182 to the attachment portion 16 can be a screw structure, be fitted by press-fitting, or be adhered by an adhesive or the like.

The abutment position of the distal end portion 181c to the face portion 11 influences the degree of restriction to deformation of the face portion 11. For example, if the abutment position of the distal end portion 181c is at the central portion of the face portion 11, the degree of restriction to the entire face portion 11 becomes high. On the other hand, if the abutment portion of the distal end portion 181c is at the peripheral portion of the face portion 11, the degree of restriction to the entire face portion becomes low. Hence, by preparing a plurality of support members 182 each configured to support the abutment member 181 so that the position where the abutment portion 181 abuts against the rear surface of the face portion 11 changes and selecting the support member 182 corresponding to each individual head body 10, the spring effect of the face portion 11 can be adjusted, and individual differences can be reduced. Note that the abutment member 181 can be prepared for each support member. However, an arrangement in which a common abutment member 181 is usable for each support member 182 is exemplified in the fifth embodiment.

FIGS. 6A to 6C exemplify three types of adjustment devices 18 (particularly, the support members 182) attachable to the attachment portion 16. The support members 182 in the examples of FIGS. 5A and 5B and in each of the examples of FIGS. 6B and 6C are arranged so as to have different positions where the abutment members 181 abut against the rear surfaces of the face portions 11 depending on how the outer shapes or directions of the threaded hole 182a are different from each other.

The support member 182 of FIG. 6A is arranged so that the abutment position of the abutment member 181 is located closer to the side of a sole portion 13 than in the example of FIGS. 5A and 5B. The support member 182 of FIG. 6B is arranged so that the abutment position of the abutment member 181 is located further on the side of the sole portion 13 than in the example of FIG. 6A. Out of the examples of FIGS. 5B, 6A, and 6B, the degree of restriction to the face portion 11 is highest in the example of FIG. 5B and lowest in the example of FIG. 6B.

The example of FIG. 6C is an example of an adjustment device 18 which has no influence on the spring effect, and its purpose is the same as the second embodiment. In the case of the fifth embodiment, the distal end portion 181c is spaced apart from the rear surface of the face portion 11 in a natural state by increasing the thickness of the support member 182. Hence, the deformation of the face portion 11 is not restricted at impact or the distal end portion 18c abuts only slightly against the face portion 11, and the spring effect of the face portion 11 is hardly influenced. On the other hand, it can avoid a case in which the position of the center of gravity, the weight of the head, and the like of a golf club head 1 differ greatly.

In the case of the fifth embodiment, since the abutment member 181 is common to the support members 182, a support member 182 can be selected, out of the plurality of support members 182, in step S4 of FIG. 3 based on the measurement result of step S3.

Note that the arrangement example of the adjustment device 18 of each of the first embodiment to the third embodiment can be applied to the abutment member 181 of the fifth embodiment.

Sixth Embodiment

In the first to fifth embodiments, the sole portion 13 is the attachment portion of the adjustment device 18. However, the attachment portion may be a crown portion 12 or a side portion 14. In addition, one pair of the adjustment device 18 and the attachment portion 16 is provided in the first to fifth embodiments. However, a plurality of pairs may be provided. If a plurality of pairs of the adjustment devices 18 and the attachment portions 16 are to be provided, all pairs may have the same structure or the pairs having different structures (for example, a mixture of one pair of the first embodiment and one pair of the fifth embodiment) may be provided.

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 Application No. 2015-142382, filed Jul. 16, 2015, which is hereby incorporated by reference herein in its entirety.

MANUFACTURING METHOD AND GOLF CLUB HEAD

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Priority Claims (1)