Method for manufacturing a golf club head

Abstract

To provide a golf club head with excellent repulsion performance and a manufacturing method thereof.SOLUTION: A golf club head 1 includes a face 2 for hitting a ball. The face 2 includes a face central area A. The golf club head 1 includes a face peripheral area B constituting a periphery of the face central area A. The face central area A and the face peripheral area B are constituted of the same metallic material. At least a part of the face peripheral area B has a degree of elasticity smaller than that of the face central area A.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a golf club head and a method for manufacturing the same.

Background Art

[0002] In recent years, in order to increase the hitting distance, various golf club heads with improved resilience performance have been proposed. For example, Patent Document 1 below describes a golf club head in which an annular thin portion is formed on the back surface of the face portion. In such a golf club head with a face thickness distribution design, the rigidity of the thin portion is relatively small, and thus, it is expected that this portion will greatly bend during hitting, thereby improving the resilience performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0004] In recent years, for various reasons, it has been desired to improve the resilience performance of a golf club head by a method different from the conventional ones.

[0005] The present invention has been devised in view of the above circumstances, and the main object thereof is to provide a golf club head capable of improving the resilience performance.

Means for Solving the Problems

[0006] The present invention relates to a golf club head having a face for striking a ball, the face including a central face region, the golf club head including a peripheral face region that constitutes the periphery of the central face region, the central face region and the peripheral face region being made of the same metal material, and at least a part of the peripheral face region having a modulus of elasticity smaller than that of the central face region.

[0007] In another aspect of the present invention, the portion having the small modulus of elasticity may be a first structure-changing portion having a metal structure different from that of the central face region.

[0008] In another aspect of the present invention, the first structure-changing portion may be a portion formed by heat treatment.

[0009] In another aspect of the present invention, the first structure-changing portion may be formed in at least a part of a region within 20 mm from the peripheral edge of the face toward the sweet spot side of the face.

[0010] In another aspect of the present invention, the first structure-changing portion may be formed in at least a part of a region within 20 mm from the peripheral edge of the face toward the rear side of the head.

[0011] In another aspect of the present invention, the first structure-changing portion may be formed in an annular shape so as to surround the central face region.

[0012] In another aspect of the present invention, the first structure-changing portion may be formed discontinuously.

[0013] In another aspect of the present invention, the central face region has a modulus of elasticity larger than that of the peripheral face region, the portion having the large modulus of elasticity is a second structure-changing portion having a metal structure different from that of the peripheral face region, and the second structure-changing portion may be a portion formed by heat treatment.

[0014] In another aspect of the present invention, the metal material may be stainless steel, mild steel, or a titanium alloy.

[0015] In another aspect of the present invention, the golf club head may be a wood type or an iron type.

[0016] Another aspect of the present invention is a method for manufacturing a golf club head, including a preparation step of preparing a golf club head having a face for hitting a ball, and a heat treatment step of heat-treating the golf club head. The preparation step prepares a golf club head in which a face central region and a face peripheral region constituting the periphery of the face central region are formed of the same metal material. The heat treatment step includes a partial heat treatment step of locally heat-treating the golf club head so that at least a part of the face peripheral region has an elastic modulus smaller than that of the face central region.

[0017] In another aspect of the present invention, the partial heat treatment step may be annealing of at least a part of the face peripheral region.

[0018] In another aspect of the present invention, the partial heat treatment step may be solution aging treatment or quenching of at least a part of the face central region.

Advantages of the Invention

[0019] By adopting the above configuration, the golf club head of the present invention can improve the repulsion performance.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be understood that the drawings include exaggerated expressions and expressions different from the dimensional ratios of actual structures in order to assist in understanding the present invention. Also, when there are a plurality of embodiments, the same or common elements are given the same reference numerals throughout the specification, and redundant explanations are omitted. Furthermore, the specific configurations shown in the embodiments and the drawings are for understanding the content of the present invention, and the present invention is not limited to the specific configurations shown.

[0022] FIGS. 1 to 3 show a front view, a plan view, and a sectional view taken along line III-III of FIG. 1 of a golf club head (hereinafter simply referred to as "head") 1 according to the present embodiment, respectively.

[0023] [Definition of reference state, etc.] In FIGS. 1 to 3, the head 1 is in a reference state. In this specification, the "reference state" of the head 1 means a state in which the head 1 is placed on the horizontal plane HP at the lie angle α (FIG. 1) and the loft angle β (FIG. 3) set for the head 1. As shown in FIG. 2, in the reference state, the shaft axis center line CL of the head 1 is arranged in the reference vertical plane VP perpendicular to the horizontal plane HP, and the head 1 is held at the lie angle α and the loft angle β. Further, the "shaft axis center line CL" is defined by the axis center line of the shaft insertion hole 5a formed in the hosel portion 5 of the head 1. In this specification, unless otherwise specified, the head 1 is described as being in the reference state.

[0024] In this specification, in the reference state of the head 1, the direction perpendicular to the reference vertical plane VP is defined as the head front-rear direction. Regarding the head front-rear direction, the side of the face 2 is the front side, and the opposite side is the rear side. Also, the direction parallel to both the reference vertical plane VP and the horizontal plane HP is defined as the toe-heel direction. Furthermore, the direction perpendicular to the horizontal plane HP is defined as the head up-down direction.

[0025] [Basic Structure of the Head] The head 1 of this embodiment is configured as a wood type. The wood type head 1 includes, for example, heads called drivers, fairway woods, etc.

[0026] As shown in FIGS. 1 to 3, the head 1 includes, for example, a face 2, a crown 3, a sole 4, and a hosel portion 5. The head 1 of this embodiment has a hollow portion i formed inside.

[0027] The face 2 is a portion for hitting the ball, and its outer surface forms a hitting surface 2a. A plurality of grooves extending in the toe-heel direction called face lines may be provided on the hitting surface 2a (not shown).

[0028] Face 2 has a sweet spot SS. As shown in FIG. 3, the sweet spot SS is the intersection of the normal line N drawn from the head center of gravity G to the hitting surface 2a of face 2 and the hitting surface 2a. The sweet spot SS is a hitting point where high repulsion can be expected.

[0029] The hitting surface 2a is defined by the peripheral edge E of face 2. In this specification, when a ridge line that defines face 2 is formed between the crown 3 and the sole 4, the peripheral edge E of face 2 is defined as that ridge line. On the other hand, when such a ridge line is not clearly formed, the peripheral edge E of face 2 is determined as follows. First, as shown in FIG. 4(A), cross-sections s1, s2, s3... including the normal line N connecting the head center of gravity G and the sweet spot SS are obtained. Then, as shown in FIG. 4(B), in each cross-section, the position Pe where the radius of curvature r of the face outer contour line Lf first becomes 200 mm from the sweet spot SS side toward the outside of the face is defined as the peripheral edge E of face 2.

[0030] The crown 3 extends rearward from the peripheral edge E of face 2 to form the upper surface of the head. A hosel portion 5 is provided on the heel side of the crown 3. A shaft insertion hole 5a for fixing a club shaft (not shown) is formed in the hosel portion 5.

[0031] The sole 4 extends rearward from the peripheral edge E of face 2 to form the bottom surface of the head. The sole 4 is, for example, the portion visible in the bottom view of the head.

[0032] The head 1 is made of a metal material. The metal material is not particularly limited, but for example, stainless steel, mild steel, titanium alloy, etc. are suitable. A part of the head 1 (for example, the crown 3) may be made of a non-metal material such as a fiber-reinforced resin. The head 1 of this embodiment is formed of, for example, a titanium alloy.

[0033] [Face Central Region · Face Peripheral Region] As shown in FIG. 1, the head 1 includes a face central region A and a face peripheral region B that constitutes the periphery of the face central region A.

[0034] The face central region A is an area including the sweet spot SS of the face 2 and is an area inside the periphery E of the face 2. The face central region A is desirably defined as an area including the main hitting position of the golfer. The face central region A of the present embodiment is defined as an area surrounded by a circle Ec with a radius of 10 mm centered on the sweet spot SS of the face 2, as shown in FIG. 1.

[0035] The face peripheral region B is an area outside the face central region A in the head 1. Also, the face peripheral region B may include not only the face 2 but also the front portions of the crown 3 and the sole 4.

[0036] In the head 1, the face central region A and the face peripheral region B are made of the same metal material. In this specification, the same metal material means that the two metal materials being compared have the same chemical composition.

[0037] As shown in FIG. 2, the head 1 of the present embodiment is formed by welding and fixing a so-called cup-shaped face member 1A and a head body 1B.

[0038] The face member 1A integrally includes, for example, the face 2 and a return portion 7 that extends from its periphery E to the rear of the head with a small length. The return portion 7 constitutes the front portions of the crown 3 and the sole 4. Such a face member 1A is formed by using one metal material and through manufacturing processes such as pressing, casting, forging, and cutting, so that the face 2 and the return portion 7 are integrally formed. By using such a face member 1A in the head 1 of the present embodiment, the face central region A and the face peripheral region B are made of the same metal material.

[0039] The head 1 of the present embodiment has at least a part of the face peripheral region B having a modulus of elasticity smaller than that of the face central region A. Such a head 1 can be configured such that the face peripheral region B with a small modulus of elasticity is easily bent during ball hitting. Therefore, the head 1 of the present embodiment can improve its repulsion performance.

[0040] In the present embodiment, since the modulus of elasticity of the face peripheral region B is configured to be smaller than that of the face central region A, there is no need to rely on the wall thickness distribution design of the face 2. Therefore, the thickness t2 of the face peripheral region B in the face 2 may be the same as the thickness t1 of the face central region A.

[0041] On the other hand, the present invention does not prevent the adoption of the face wall thickness distribution design. Therefore, the present invention may further enhance the effect of improving the repulsion performance by using the face wall thickness distribution design in combination. In a preferred embodiment, the thickness t2 of the face peripheral region B is formed smaller than the thickness t1 of the face central region A. Thereby, the bending stiffness of the face peripheral region B is more effectively reduced, and the face peripheral region B can be more effectively bent during ball hitting, thereby improving the repulsion performance.

[0042] The head 1 of the present embodiment has at least a part of the face peripheral region B having a modulus of elasticity smaller than that of the face central region A in the face central region A and the face peripheral region B made of the same metal material. Such a head 1 can be realized in two forms: relatively reducing the modulus of elasticity of the face peripheral region B (the first embodiment) and relatively increasing the modulus of elasticity of the face central region A (the second embodiment). Hereinafter, these specific embodiments will be described respectively.

[0043] [First Embodiment] In the first embodiment, by relatively reducing the elastic modulus of the face peripheral region B, a difference in elastic modulus is provided between the face central region A and the face peripheral region B. In this embodiment, the portion with a small elastic modulus in the face peripheral region B is formed by a first structure change portion 10 that is processed to have a metal structure different from that of the face central region A.

[0044] The first structure change portion 10 is formed, for example, by locally heat-treating the face peripheral region B. Examples of the heat treatment for reducing the elastic modulus of the metal material include various annealing processes (full annealing, stress relief annealing, etc.). Annealing is performed, according to convention, by holding the target region at a high temperature and then slowly cooling it. The annealed portion has its structure homogenized due to a reduction in lattice defects and recrystallization in the metal structure, and the elastic modulus decreases due to a reduction in residual stress. Therefore, by locally annealing the face peripheral region B, the first structure change portion 10 with a small elastic modulus is locally formed in the same metal material.

[0045] As shown in FIG. 1, the first structure change portion 10 is preferably formed in an annular shape so as to surround the face central region A. Thereby, when hitting a ball, the face peripheral region B can be bent more greatly, and the repulsion performance of the head 1 is further improved. In other aspects, as shown in FIG. 5(A), the first structure change portion 10 may be formed discontinuously in the face peripheral region B. Further, the first structure change portion 10 may be formed in a single strip, as shown in FIGS. 5(B) and 5(C).

[0046] As shown in FIG. 3, the first structure change portion 10 is preferably formed in a region L1 within 20 mm, more preferably within 15 mm, and even more preferably within 10 mm from the peripheral edge E of the face 2 toward the sweet spot SS side of the face 2. By forming the first structure change portion 10 close to the peripheral edge E of the face 2 in this way, the bending of the face 2 during ball hitting can be made larger, and the repulsion performance of the head 1 is further improved.

[0047] In another aspect, as shown in FIG. 6, the first tissue change portion 10 may be formed in the crown 3 and / or the sole 4 behind the face 2 as the face peripheral region B. In this case, the first tissue change portion 10 is formed in a region L2 within 20 mm, more preferably within 15 mm, and even more preferably within 10 mm from the periphery E of the face 2 toward the rear side of the head. In this way, even if the first tissue change portion 10 is formed behind the face 2, the deflection of the face 2 during ball hitting can be increased more, and the repulsion performance of the head 1 can be improved more effectively. Note that the first tissue change portion 10 shown in FIG. 6 and the first tissue change portion 10 shown in FIG. 3 may be used in combination.

[0048] In any of the aspects of FIGS. 3 and 6, if the first tissue change portion 10 approaches too close to the periphery E of the face 2, there is a possibility that sufficient deflection of the face 2 during ball hitting cannot be obtained. From such a viewpoint, the first tissue change portion 10 is preferably formed at a distance of 3 mm or more, more preferably 4 mm or more, and even more preferably 5 mm or more from the periphery E of the face 2.

[0049] As shown in FIG. 3, the width W of the first tissue change portion 10 measured in the direction orthogonal to the periphery E of the face 2 is not particularly limited, but in order to improve the repulsion performance, for example, it is desirably 1 mm or more, preferably 3 mm or more, and even more preferably 5 mm or more. On the other hand, the width W of the first tissue change portion 10 is desirably, for example, 20 mm or less, preferably 15 mm or less, and even more preferably 10 mm or less.

[0050] Also, in order to sufficiently increase the repulsion performance, the ratio (Em1 / Em2) of the elastic modulus Em1 of the face central region A to the small elastic modulus Em2 of the face peripheral region B is, for example, 1.1 or more, preferably 1.2 or more, and more preferably 1.3 or more. On the other hand, if the ratio (Em1 / Em2) is too large, stress concentration and the like are likely to occur at the boundary position of the first tissue change portion 10. From such a viewpoint, the ratio (Em1 / Em2) is, for example, 2.0 or less, preferably 1.8 or less, and more preferably 1.6 or less.

[0051] [Second Embodiment] FIG. 7 shows a front view of the head 1 as the second embodiment. In the second embodiment, by relatively increasing the elastic modulus of the face central region A, a difference in elastic modulus is provided between the face central region A and the face peripheral region B. In the second embodiment, the portion with a large elastic modulus in the face central region A is formed by a second structure change portion 20 that is processed to have a metal structure different from that of the face peripheral region B.

[0052] The second structure change portion 20 is formed, for example, by locally heat-treating the face central region A. Examples of heat treatment for increasing the elastic modulus of a metal material include solution aging treatment and quenching.

[0053] Solution aging treatment is to perform aging treatment after solution treatment to precipitate fine intermetallic compounds in the metal structure and increase the elastic modulus of the material. Therefore, by locally performing solution aging treatment on the face 2, a second structure change portion 20 with a large elastic modulus is locally formed in the same metal material. Solution aging treatment is suitable for, for example, titanium alloys and maraging steels. On the other hand, quenching is to obtain a martensite structure by locally maintaining the target region at a high temperature and then rapidly cooling it, thereby making the material highly elastic. Therefore, quenching is mainly suitably used for steel materials. As described above, when forming the second structure change portion 20, an optimal heat treatment may be appropriately selected according to the target metal material.

[0054] In this embodiment, for example, after forming the face member 1A with a metal material having a small elastic modulus, by locally increasing the elastic modulus of the face central region A, a head 1 excellent in repulsion performance can be provided.

[0055] In addition, in a head that has already been made highly resilient over a wide area of the face 2 by face thickness distribution design or the like, an index related to the resilience performance such as the CT value or COR may exceed the upper limit defined by the golf rules. In such a case, by forming the second structure change portion 20 at a specific location of the face 2 (for example, the measurement location of the resilience performance), the resilience performance at that portion can be locally reduced to within the golf rules. Therefore, such a head 1 can provide a high-resilience area over a wider range of the face 2 than before while satisfying the golf rules.

[0056] [Other Embodiments] The head 1 may be configured not only as a wood type but also as an iron type, a hybrid type, or the like. FIG. 8 shows a front view of an iron-type head 1. In this embodiment, the face 2 includes a face central region A and a face peripheral region B which is the outer region thereof, and a first structure change portion 10 is formed in the face peripheral region B.

[0057] [Method for Manufacturing Head] The head 1 of this embodiment can be manufactured including a preparation step of preparing the head 1 having the face 2 and a heat treatment step of heat-treating the head 1.

[0058] As described above, the head 1 prepared in the preparation step is formed of the same metal material for the face central region A and the face peripheral region B that constitutes the periphery of the face central region A. In a desirable aspect, as shown in FIG. 2, the head 1 is formed (prepared) by fixing a cup-shaped face member 1A and a head body 1B that constitutes the rear portion thereof by welding. Needless to say, the face member may be plate-shaped without the return portion 7.

[0059] The heat treatment step includes a partial heat treatment step of partially heat-treating the head 1 so that at least a part of the face peripheral region B has an elastic modulus smaller than the elastic modulus of the face central region A.

[0060] The partial heat treatment process can include, for example, a partial annealing process of the face peripheral region B as shown in FIG. 9. For such partial annealing, for example, a laser beam 32 output from the laser oscillator 30 can be used as a heat source. More specifically, by relatively moving the laser oscillator 30 with respect to the face 2, the laser beam 32 can be locally irradiated to a predetermined position in the face peripheral region B. The laser beam 32 is desirable in that it can reduce the thermal influence on parts other than the irradiated part.

[0061] In the partial annealing, the laser beam 32 is repeatedly irradiated locally to the face peripheral region B of the face 2 (not irradiated to the face central region A), and after keeping that part at a high temperature, it is gradually cooled. As a result, the annealed part of the face peripheral region B has a relatively small elastic modulus and becomes the above-described first structure change part 10.

[0062] Regarding the annealing temperature for obtaining the first structure change part 10, it can be appropriately determined according to the target metal material. For example, for titanium, it can generally be carried out in the following temperature range.

[0063]

Table 1

[0064] The partial heat treatment process may be, instead of the above partial annealing process, or in addition to the above partial annealing process, for example, a partial solution aging process of the face central region A, or a partial quenching process.

[0065] For example, in the partial quenching process, as shown in FIG. 9, the laser beam 32 is repeatedly irradiated partially to the face central region A of the face 2 (not irradiated to the face peripheral region B), and after keeping the irradiated part at a high temperature, it can be carried out by rapid cooling. As a result, the quenched part of the face central region A has a relatively high elastic modulus and becomes the above-described second structure change part 20.

[0066] Regarding the temperature of the partial solutionizing aging treatment or partial quenching for obtaining the second structure change portion 20, it can be appropriately determined according to the target metal material. For example, the solutionizing and aging treatment of a titanium alloy can generally be carried out in the following temperature range.

[0067]

Table 2

[0068] The above partial heat treatment process has the advantage that after manufacturing the head 1, the repulsion performance can be adjusted to be high or low. For example, in the adjustment of the repulsion performance by the wall thickness distribution design of the face 2, since machining of the back surface of the face 2 is required, the repulsion performance cannot be adjusted. On the contrary, in the manufacturing method as in this embodiment, even after the face member 1A is welded and fixed to the head body 1B, it is possible to increase the repulsion performance by the partial annealing process, and to decrease the repulsion performance by the partial solutionizing aging process or the partial quenching process.

[0069] In the partial heat treatment process, the conditions of the laser beam 32 are not particularly limited. For example, in a laser oscillation device using a Yb (ytterbium) disk (lens), it is desirable to carry out the process in the range of an output of about 500 to 2000 W and a scanning speed of about 50 to 400 mm / min.

[0070] In the portion irradiated with the laser beam 32, burn marks, unevenness, etc. may be formed on the surface. In order to improve the appearance of the face 2, it is desirable to, for example, polish the locally annealed portion. After that, the face 2 may be painted as necessary.

[0071] The above partial heat treatment process can be carried out by various methods other than the laser beam. For example, as the heat source, a flame, an electron beam, a high-frequency current, etc. can be used.

[0072] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above specific disclosure.

Example

[0073] Hereinafter, more specific and non-limiting examples of the present invention will be described. Wood-type golf club heads having the basic structures of FIGS. 1 to 3 were manufactured based on the specifications in Table 3, and their repulsion performances were evaluated. Also, as a comparative example, one without a partial heat treatment process was prepared, and its repulsion performance was similarly evaluated. The thickness of the face is constant at 3.1 mm for all the heads.

[0074] In the partial heat treatment process, a laser oscillator using a Yb disk was used, the output was 530 to 570 W, and the scanning speed was 1000 mm / min. Also, the portion of the head to be annealed was repeatedly irradiated with a laser beam, held at a temperature range of about 780 to 800 °C for about 10 minutes, and then air-cooled.

[0075] Regarding the repulsion performance, the COR at the sweet spot was measured. COR means the coefficient of restitution and was measured based on the "Interim Procedure for Measuring the Coefficient of Restitution of an Iron Clubhead Relative to a Baseline Plate Revision 1.3 January 1, 2006" defined by the USGA (United States Golf Association). In Table 3, it is an index display with the COR of the comparative example set to 100, and the larger the numerical value, the higher the repulsion performance tends to be.

[0076] The test results are shown in Table 3.

Table 3

[0077] As a result of the test, it was confirmed that the golf club head of the example is excellent in repulsion performance compared to the head of the comparative example.

Explanation of symbols

[0078] 1 Head 2 Face 10 First tissue change part 20 Second tissue change part A Face central region B Face peripheral region SS Sweet spot

Claims

1. A method for manufacturing a golf club head, comprising: a preparation step of preparing a golf club head having a face for striking a ball; a heat treatment step of heat treating the golf club head; wherein the preparation step prepares a golf club head in which a face central region and a face peripheral region constituting the periphery of the face central region are formed of the same metal material; the heat treatment step includes a partial heat treatment step of locally heat treating the golf club head such that at least a part of the face peripheral region has a modulus of elasticity smaller than that of the face central region; the partial heat treatment step includes a step of locally increasing the modulus of elasticity by heat treating a measurement location of the resilience performance of the face when an index related to the resilience performance of the prepared golf club head exceeds an upper limit defined by golf rules, and reducing the resilience performance within the golf rules; A method for manufacturing a golf club head.

2. The method for manufacturing a golf club head according to claim 1, wherein the step of reducing the resilience performance within the golf rules includes solution aging treatment or quenching for the measurement location.

3. The face central region has a modulus of elasticity larger than that of the face peripheral region, the portion with the larger modulus of elasticity is a second structure change portion having a metal structure different from that of the face peripheral region, and the second structure change portion is a portion formed by the heat treatment. The method for manufacturing a golf club head according to claim 1.

4. The method for manufacturing a golf club head according to any one of claims 1 to 3, wherein the metal material is stainless steel, mild steel or a titanium alloy.

5. The method for manufacturing a golf club head according to any one of claims 1 to 4, wherein the golf club head is of a wood type.

6. The method for manufacturing a golf club head according to any one of claims 1 to 4, wherein the golf club head is of an iron type.

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