JP4478011B2 - Manufacturing method of golf club head - Google Patents

Description

The present invention relates to a method for manufacturing a golf club head using a magnesium alloy, and more particularly to a method capable of improving aesthetics and durability over a long period of time by suppressing corrosion of the magnesium alloy.

  Magnesium alloy has a very small specific gravity (about 1.7) and a high specific strength as a practical alloy. For this reason, magnesium alloy can be used for some or all of the golf club heads, so that the head volume can be increased without losing the strength, and the center of gravity of the head can be designed at an optimal position, giving freedom to weight distribution design. There are benefits that can be enhanced. However, magnesium alloys belong to the thermodynamically most active class (standard potential: -2.363 V) and therefore have a strong corrosion tendency to be rapidly oxidized in the atmosphere. Such oxidation (rust) is undesirable because it significantly impairs the appearance of the head. The following Patent Documents 1 and 2 have been proposed as golf club heads using a magnesium alloy.

JP 2004-24736 A JP-A-9-38249

  Patent Document 1 teaches that a stainless steel or titanium alloy thin plate is joined to the outer surface of a head member made of a magnesium alloy to suppress corrosion. However, such a head is expensive because the structure is very complicated. Moreover, it is difficult to affix a thin plate such as a titanium alloy on the outside of the magnesium alloy. As a result, corrosion progresses from the joint between both members, and peeling or the like is likely to occur.

  In Patent Document 2, as shown in FIG. 7A, after a crown plate b made of a non-magnesium alloy is welded to a head body a made of a magnesium alloy, and a joint j is finished through a blasting process or the like. 7B, it is described that a protective film d for rust prevention is formed on the head main body a. However, with such a method, a protective film cannot be formed on the joint surface e of the head body a that has already been welded to the crown plate b.

  Since the golf club head repeatedly hits the ball, very small fine cracks c are likely to occur at the joint j such as a weld due to metal fatigue or the like. There may be a case where a pinhole remains in the junction j. When a protective film is not formed on the joint surface e of the head main body a made of a magnesium alloy as in Patent Document 2, air or moisture is transferred from the microcracks c or the like generated in the joint j to the joint surface of the head main body a. There is a defect that reaches e and corrodes the joint surface e. Such corrosion lowers the joint strength of the joint j and impairs the durability of the head. Such a problem can also occur when the head body a and the crown plate b are joined using an adhesive.

  The present invention has been devised in view of the above circumstances, and includes a first member made of a magnesium alloy on at least an outer surface facing the outer surface side of the head and a bonding surface bonded to the second member. Based on the formation of a protective film for preventing corrosion of the first member, corrosion of the magnesium alloy can be reliably suppressed, and aesthetics can be maintained over a long period of time. Another object of the present invention is to provide a method of manufacturing a golf club head that can be improved.

The invention according to claim 1 of the present invention has a plate-like first member made of a magnesium alloy, and an opening in which the first member is disposed, and the head has an outer surface around the opening. A golf club head that is recessed in a step shape and has a support surface on which the peripheral edge of the first member is placed, and at least a second member made of a non-magnesium alloy is joined to produce a golf club head having a hollow structure In this manufacturing method, prior to joining the first member and the second member, joining the second member and the outer surface of the first member facing at least the outer surface of the head. A first rust-preventing step for forming a protective film for preventing corrosion of the first member on a surface, a joining step for joining the first member and the second member, and the first member And the outer surface of the head including the joint portion of the second member A polishing step of the outer surface of the first member and the second member is polished flush, after the polishing step, the entire area of said outer surface of said first member, said first member And a second rust-preventing step for forming the protective film on the inner surface facing the hollow portion.

The invention according to claim 2, after the previous SL second anticorrosive process, according to claim 1, characterized in that it further comprises a film removal step of removing the adhered coating of the outer surface of the second member This is a method for manufacturing a golf club head.

According to a third aspect of the present invention, the golf club head includes a neck portion having a shaft insertion hole into which one end of the shaft is mounted, and the second rust prevention step includes inserting the shaft of the neck portion 7 into the shaft. The golf club head manufacturing method according to claim 1, further comprising a step of spreading a treatment liquid for forming a protective film from the opening provided in the hole and communicating with the hollow portion to the hollow portion of the head.

According to a fourth aspect of the present invention, there is provided the golf club head manufacturing method according to any one of the first to third aspects, wherein the first member is joined to the second member with an adhesive .

A fifth aspect of the present invention is the golf club head manufacturing method according to any one of the first to fourth aspects , wherein the thickness t of the first member is not less than 0.4 mm and not more than 1.5 mm .

The invention according to claim 6 is the ratio (Sc / Sa) of the covering area Sc, which is the area of the first member covering the opening of the second member, to the total surface area Sa of the head. The golf club head manufacturing method according to claim 1, wherein the golf club head is 0.3 or more and 0.9 or less . According to a seventh aspect of the present invention, in the first and second rust prevention steps, a chemical conversion treatment is performed in which the first member is immersed in an aqueous electrolyte containing no vanadium acid and containing no chromium in a room temperature environment for 5 minutes. A golf club head manufacturing method according to claim 1, comprising: According to an eighth aspect of the present invention, the height of the center of gravity of the head from the horizontal plane is 35 mm in the reference state where the head is placed on the horizontal plane at the specified lie angle and real loft angle by the method according to any one of the first to seventh aspects. A golf club head manufacturing method comprising manufacturing the following golf club head.

The golf club head obtained by the present invention is constituted by joining at least a first member made of a magnesium alloy and a second member made of a non-magnesium alloy. The first member has a protective film for preventing corrosion of the first member on at least an outer surface facing the outer surface side of the head and a bonding surface bonded to the second member. Therefore, even when air or moisture reaches the bonding surface of the first member from the fine cracks or pinholes generated at the bonding portion, corrosion from this portion can be prevented. Therefore, the durability of the joint can be maintained high without impairing the appearance of the head.

Further, in the present invention, prior to joining the first member and the second member, at least the outer surface of the first member made of magnesium alloy facing the outer surface side of the head and the joining surface joined to the second member. And a protective film (first rust prevention step) is formed. Also after joining the first member and the second member, further protective coatings over the entire and the inner surface of the outer side surface of the first member (second anticorrosive process) is formed.

In the golf club head manufactured through these treatments, a protective film is formed on the joint surface of the magnesium alloy by the first rust prevention process, so that air and moisture are generated from fine cracks and pinholes generated at the joint portion. Even when the joining surface of the first member is reached, corrosion from this portion can be prevented. In addition, after the first member and the second member are joined, the protective film on the outer surface of the first member may be lost due to, for example, the influence of heat at the time of joining or polishing. This can be repaired by the rust prevention process. Moreover, when water enters the hollow portion of the head, the humidity in the hollow portion i increases, but the protective coating can be formed as thick as possible on the inner surface to enhance the rust prevention effect. Therefore, the golf club head manufactured according to the present invention has excellent aesthetics over a long period of time and can maintain durability of the joint portion.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an overall perspective view of the golf club head of the present embodiment. 2 is a sectional view taken along line AA in FIG. 1, FIG. 3 is a sectional view taken along line BB, and FIG. 4 is an exploded perspective view.

  A golf club head 1 (hereinafter sometimes simply referred to as “head”) 1 includes a face portion 3 having a face surface 2 that is a surface for hitting a ball, and an upper surface of the head connected to the upper edge 2 a of the face surface 2. The crown portion 4 that is formed, the sole portion 5 that is connected to the lower edge 2b of the face surface 2 and forms the bottom surface of the head, and the crown portion 4 and the sole portion 5 are joined to each other through the back face from the toe side edge 2c of the face surface 2. A side portion 6 that extends to the heel side edge 2d of the surface 2, and a neck portion 7 that is disposed in the vicinity of the heel side intersection of the face portion 2, the crown portion 3, and the side portion 5 and to which one end of a shaft (not shown) is attached. And a hollow structure and a wood type having a hollow portion i provided therein. The hollow portion i may remain as it is or may be appropriately filled with a foamed resin or the like.

For wood type head of the present embodiment, the volume of the head, for example, 200 cm ³ or more, more preferably 260 cm ³ or more, more preferably 300 cm ³ or more, particularly preferably 320 cm ³ or more. By increasing the head volume in this way, it is possible to increase the moment of inertia of the head and improve the resilience performance.On the other hand, if the head volume is too large, the club weight increases and the swing balance tends to be impaired. is there. From this point of view, the upper limit of the volume of the head, for example, 470 cm ³ or less, more preferably 420 cm ³ or less.

  The head 1 is configured by joining a first member M1 made of a magnesium alloy and a second member M2 made of a non-magnesium alloy.

  In the present embodiment, the first member M1 is exemplified by a plate-like member disposed on the crown portion 4 that forms the upper surface of the head. The second member includes the face portion 3, the sole portion 5, the side portion 6, the neck portion 7, and a crown edge portion 9 surrounding the opening portion O in which the first member M1 is disposed. Yes.

  The second member M2 is made of a material other than the magnesium alloy, and a metal material having a specific gravity greater than that of the first member M1, such as an aluminum alloy, titanium, a titanium alloy, and stainless steel, is particularly suitable. Further, the second member M2 does not need to be formed of one type of material, and may be, for example, a composite body in which a fiber reinforced resin and a metal material are combined. In this case, it is desirable that at least the crown edge 9 is made of a metal material.

  The second member M2 can be made by various methods. For example, any of a cast product in which the respective parts are integrally formed by casting or a joined product in which two or more parts are joined may be used. The second member M2 of the present embodiment is exemplified by a cast product obtained by integrally casting a titanium alloy (Ti-6Al-4V) with lost wax precision casting.

  In this embodiment, the crown edge portion 9 of the second member M2 is provided on the crown surface portion 9a that forms the outer surface of the head 1 and on the inner edge side thereof, and a step from the crown surface portion 9a to the hollow portion i side. A support surface 9b that is recessed in a shape, and an inner side surface 9c that connects the crown surface portion 9a and the support surface 9b.

  The periphery of the first member M1 is placed on and joined to the support surface 9b. The support surface 9b of this embodiment is continuously provided in an annular shape around the opening O, and continuously supports the periphery of the first member M1. Such a support surface 9b is useful for firm joining of the first and second members M1 and M2. The surface of the support surface 9b is recessed from the crown surface portion 9a toward the hollow portion i with a thickness substantially equal to the thickness of the first member M1. Therefore, when the first member M1 is joined to the support surface 9b, the outer surfaces of the first member M1 and the crown surface portion 9a are useful for being substantially flush with each other. Accordingly, the subsequent polishing and finishing steps are facilitated, and the head productivity is improved.

  The first member M1 is made of a magnesium alloy. In this specification, the magnesium alloy is defined as an alloy containing the largest amount of magnesium per unit weight of the alloy, but in this specification, pure magnesium is included. Moreover, although it does not specifically limit as an alloy element added to magnesium, For example, Al, Zn, Cu, Mn, Zr, Fe, and / or Ni etc. can be mentioned.

  In the present embodiment, the first member M1 has a contour shape along the inner side surface 9c of the crown edge portion 9 and slightly smaller than that. Therefore, the first member M1 can be placed on the support surface 9b without interfering with the inner side surface 9c of the crown edge portion 9. Therefore, when the first member M1 is joined to the crown edge portion 9, the first member M1 can be temporarily fixed and positioned, which helps to facilitate the joining work of both members. Such a first member M1 can be easily formed by, for example, a die casting method, a thixo molding method, a pressing method, and a press forging method.

  The magnesium alloy has a very small specific gravity, for example, 1.5 to 1.8. Therefore, the low center of gravity can be easily realized by arranging the first member M1 made of a magnesium alloy on the top of the head. Specifically, as shown in FIG. 2, in a reference state in which the head 1 is placed on the horizontal plane HP at a specified lie angle and real loft angle, the height h of the head gravity center G from the horizontal plane HP is 35 mm or less, More preferably, it is 30 mm or less, More preferably, it is 25 mm or less, and can be set lower.

  Further, although not particularly limited, the thickness t of the first member M1 is preferably 0.4 mm or more, more preferably 0.6 mm or more, and further preferably 0.8 mm or more. The upper limit is preferably 1.5 mm or less, more preferably 1.3 mm or less, and still more preferably 1.0 mm or less. If the thickness t is less than 0.4 mm, the strength of the first member M1 may be insufficient, and damage or the like may occur due to impact at the time of hitting the ball. Is excessively increased, the resilience of the head is lowered, and the weight reduction effect cannot be obtained.

  The first member M1 is supported by the support surface 9b of the second member M2 in the area of the portion covering the opening O of the second member M2 (in other words, out of the surface area of the first member M1). The ratio (Sc / Sa) of the covering area Sc, which is the area of the uncovered portion, to the total surface area Sa of the head 1 is 0.3 or more, more preferably 0.5 or more, and even more preferably 0.7 or more. Thereby, the weight of the second member M2 can be more effectively replaced with a low specific gravity magnesium alloy, and an effective weight reduction effect can be obtained. Conversely, even if the covering area Sc is too large, the rigidity of the crown portion 4 tends to be low and the strength tends to decrease. From such a viewpoint, the ratio (Sc / Sa) is preferably 0.9 or less, more preferably 0.8 or less. The total surface area of the head 1 is measured by filling the shaft insertion hole 7a of the neck portion 7.

  The arrangement position of the first member M1 is not limited to the crown portion 4, and may be another position. Magnesium alloys generally have high vibration absorption performance that attenuates vibrations by converting them into heat. Therefore, the vibration of the crown portion 4 generated at the time of hitting the ball is effectively damped, and it is useful for obtaining a good shot feeling.

  FIG. 5 shows an enlarged view of part C of FIG. In the head 1 of the present embodiment, a first member M1 and a second member M2 are joined via an adhesive 15.

  Further, the first member M1 is for preventing corrosion of the first member M1 on at least the outer surface 10 facing the outer surface side of the head 1 and the joint surface 11 joined to the second member M2. A protective coating 12 is provided. In FIG. 5, the protective film 12 is exaggeratedly drawn as having a predetermined thickness for easy understanding, but it is needless to say that the actual thickness is as thin as several μm.

  The protective film 12 includes a first protective film 12a that covers the outer surface 10 of the first member M1, a second protective film 12b that covers the bonding surface 11 of the first member M1, and the first member M1. And a third protective film 12c covering the inner surface 13 facing the hollow portion i.

  The outer side surface 10 of the first member M1 is visually recognized from the outside. Accordingly, the first protective film 12a covering the outer surface 10 can prevent the appearance of rust.

  Further, in the present embodiment, the joint surface 11 of the first member M1 faces the support surface 9b of the crown edge portion 9 and faces the inward peripheral edge surface 11a joined to the support surface 9b and the inner side surface 9c of the crown edge portion 9. And an outer end face 11b facing and joined thereto. The second protective film 12b covers both the inward peripheral edge surface 11a and the outer end surface 11b over the entire area.

  As described above, fine cracks or pinholes are likely to occur in the joint portion (the adhesive 15 in this example) that joins the first member M1 and the second member M2. When such a crack or the like occurs, air or moisture can reach the joint surface 11 of the first member M1 through the crack or the like. In the conventional head, since no protective film is formed on the bonding surface 11, it is presumed that corrosion has progressed on the bonding surface 11 due to the air or the like and the bonding strength with the second member M 2 has been reduced. . In the head of the present invention, such corrosion at the joint can be effectively prevented by the second protective film 12b disposed on the joint surface 11. Therefore, corrosion at the joint between the first member M1 and the second member M2 is suppressed over a long period of time, and high durability is exhibited.

In the present embodiment, by covering the inner surface 13 of the first member M1 in the third protection film 12c, but not visible from the outside, the rust in the first member M1 Oite the hollow portion i side occurs Can be prevented. Furthermore, in this embodiment, the 4th protective film 12d which covers the outer surface 16 which faces the outer surface side of the head of the 2nd member M2 is provided. Such a structure originates in the formation method of the protective film mentioned later. However, it is not particularly limited to such an embodiment, and for example, the third to fourth protective films 12c and 12d can be omitted.

  Various protective coatings 12 can be used as long as they prevent corrosion of the first member M1 made of a magnesium alloy. For example, various platings, coatings by chemical conversion treatment, or coatings by anodizing treatment are suitable for practical use. As the plating, for example, one or more of electroless nickel plating, zinc plating, or copper plating can be employed. Further, in the chemical conversion treatment, a chromate treatment or a non-chromate treatment can be adopted as a classification based on the presence or absence of chromium in the treatment liquid. For the latter non-chromate treatment, for example, manganese-based, phosphate-based or oxalic acid-based, molybdenum / tungsten-based and zirconium-based processing solutions can be used, which is particularly preferable in that no harmful chromium is used.

  The joining method of the 1st member M1 and the 2nd member M2 is not specifically limited. However, when both are joined by welding, the first or second protective coating 12a, 12b of the first member M1 may be altered or destroyed by welding heat. In this case, not only the outer surface 10 of the first member M1, but also the welded surface is corroded easily due to air or the like entering from that portion when a fine crack or the like is generated in the welded portion due to impact. From this point of view, the bonding method of the two members is particularly preferably adhesion.

  In this connection, it is desirable that the first member M1 and the second member M2 have a sufficient adhesion area. In the present embodiment, since the support surface 9b of the second member M2 is formed with a relatively large width L, a sufficient adhesion area is secured between the two. From such a viewpoint, the width L of the support surface 9b is preferably 2 mm or more, more preferably 3 mm or more, and further preferably 5 mm or more. Conversely, even if the width L is too large, there is a tendency for useless weight to be generated. Therefore, the width L of the support surface 9b is preferably 15 mm or less, more preferably 10 mm or less.

  In addition, the thickness tc of the adhesive 15 (the thickness after curing) is not particularly limited, but if the thickness tc of the adhesive is too small, the first member M1 and the second member Fine gaps are formed between the joint surfaces with the member M2, and rust is likely to occur on the joint surface 11 of the first member M1 due to air remaining in the gap portions. On the other hand, if the thickness tc of the adhesive is too large, the shearing force acting on the adhesive 15 when the ball is hit tends to cause adhesion peeling or destruction of the adhesive layer, and rust may be generated from the portion. is there. From such a viewpoint, the thickness tc of the adhesive is preferably 0.01 mm or more, more preferably 0.05 mm or more, and the upper limit is preferably 0.20 mm or less, more preferably 0.13 mm or less. A range is desirable.

  The adhesive 15 preferably has strong adhesive strength and resistance to deterioration that can withstand high temperature and high humidity. Specifically, an epoxy-based adhesive is suitable. Note that it is particularly desirable to use a one-pack type epoxy adhesive from the viewpoint of productivity and the like.

  In the case of a one-pack type adhesive, the viscosity is preferably 200 Pas or more, more preferably 400 Pas or more, more preferably 600 Pas, for example, in a B-type rotational viscometer (BS type, rotor # 7, 10 rpm, 25 ° C.). The above is desirable, and the upper limit is preferably 2000 Pas or less, more preferably 1500 Pas or less, and still more preferably 1000 Pas or less. In the case where the viscosity of the adhesive is less than 600 Pas or greater than 2000 Pas, both of the coating properties are liable to be poor and the adhesive is poorly applied. As a result, there is a tendency that the adhesive strength is reduced or rust is generated at the poorly applied part. is there.

  Further, the adhesive 15 desirably has a small dielectric constant. In the present invention, since the second protective film 12b is present on the joint surface 11 of the first member M1, this is not a serious problem. However, if a pinhole or the like is present in the second protective film 12b, However, by reducing the dielectric constant of the adhesive 15, the corrosion of the first member M1 can be suppressed as much as possible. The specific value is preferably 10 or less, more preferably 8 or less, in the dielectric constant (measuring frequency f = 1 kHz) obtained according to JISK6911. The lower limit of the dielectric constant does not need to be particularly limited, but may be set to 2 or more, 3 or more, or 4 or more, for the reason of obtaining an adhesive having desirable adhesive strength or the like.

  Examples of the adhesive satisfying these physical properties include Scotch Weld (registered trademark) EW2010 manufactured by Sumitomo 3M Limited.

Next, a method for manufacturing the head 1 as described above will be described.
In the present embodiment, prior to the joining of the first member M1 and the second member M2, corrosion of the first member M1 is prevented on at least the outer surface 10 and the joining surface 11 of the first member M1. A first rust prevention step for forming the protective coating 12 is performed. In the present embodiment, the first rust prevention step is performed including degreasing, pickling, neutralization, chemical conversion, and drying.

  A degreasing process is performed by immersing the 1st member M1 in the process liquid containing NaOH, a phosphoric acid compound, and surfactant, for example. Although immersion time and temperature can be determined suitably, it is desirable to carry out at the temperature of 70-80 degreeC, for example for immersion time 10 minutes or more. Prior to degreasing, the first member M1 may be subjected to a surface treatment, for example, by shot blasting. Moreover, after the degreasing treatment, the first member M1 is washed with water for about 250 to 300 seconds using, for example, running water.

  The pickling treatment is performed by immersing the first member M1 in a solution containing phosphoric acid, hydrofluoric acid, nitric acid or the like (for example, H3 PO4) according to a conventional method. After the pickling treatment, the first member M1 is washed with water for about 200 to 300 seconds using running water, for example.

  The neutralization treatment is performed by immersing the first member M1 in an aqueous NaOH solution having a concentration of about 10% for 60 to 70 seconds in a room temperature environment. Thereafter, the first member M1 is washed with water for about 200 to 300 seconds using, for example, running water.

  The chemical conversion treatment is performed by immersing the first member M1 in an aqueous electrolyte containing no chromium and containing vanadate in a room temperature environment for about 5 minutes. Thereby, the 1st thru | or 3rd protective film 12a thru | or 12c are firmly formed in the whole surface of the 1st member M1. In addition, harmful chromium is not used in the processing solution, which helps to protect the environment. In the rust prevention treatment of the first member M1, a protective film 12 is formed at least on the outer surface 10 which forms the outer surface of the head when the head 1 is configured and the joining contact 11 of the second member M2. However, it is preferable to form the protective film 12 on the entire surface as in the present embodiment.

  Moreover, after the chemical conversion treatment, the first member M1 is washed with running water for about 200 to 300 seconds. After washing with water, a drying process is performed. The drying process is performed by putting the first member M1 into an oven at 120 to 130 ° C. for at least 30 minutes.

  Next, as shown in FIG. 6A, a joining step for joining the first member M1 having the protective film 12 formed thereon and the second member M2 is performed. In this embodiment, as described above, both members are joined using the adhesive 15.

  As shown in FIG. 6A, in the joining step, the adhesive 15 that joins the first member M1 and the second member M2 protrudes from the joined portion to the outside of the head or due to manufacturing errors or the like. In some cases, the outer surfaces of the member M1 and the second member M2 are not flush with each other. For this reason, a polishing process for polishing the outer surface of the head 1 including the bonded portion is usually performed after the bonding process regardless of adhesion or welding. Such a polishing process is also performed in the present embodiment.

  In the polishing step, for example, as shown in FIG. 6B, the outer surface 10 of the first member M1, the outer surface 16 of the second member M2, and the adhesive 15 protruding from between them are scraped and smoothed. The For this reason, at least a part of the first protective film 12a formed on the outer surface 10 of the first member M1 is lost. Therefore, after the polishing step, as shown in FIG. 6C, a second rust prevention step for forming the protective film 12 over at least the entire outer surface 10 of the first member M1 is performed. Thereby, the head 1 having the protective film 12 can be formed on the entire outer surface 10 and the bonding surface 11 of the first member M1. Thus, in the manufacturing method of the present embodiment, even when the head 1 is polished after the joining, the corrosion of the first member M1 can be prevented and the aesthetics of the head 1 can be maintained.

  The 2nd rust prevention process of this embodiment is performed in the procedure similar to a 1st rust prevention process. Specifically, each of the steps performed by the first member M1 alone is different in that it is performed as the head 1 in which the first member M1 and the second member M2 are joined. Are the same.

The protective coating 12 is formed on the entire outer side surface 11 of the first member M1, Ru including the inner side surface 13. When water enters the hollow part i of the head 1, the humidity in the hollow part i increases. For this reason, it is desirable to form a coating film by chemical conversion treatment on the inner side surface 13 as thick as possible to enhance the rust prevention effect.

  In this case, as shown in FIG. 3, for example, by providing an opening 7 h that can communicate with the hollow portion i of the head 1 in the shaft insertion hole 7 a provided in the neck portion 7. Can be easily distributed to the hollow portion i of the head 1. Therefore, even after the head 1 is formed, the protective film 12 can be easily formed on the inner surface 13 of the first member M1.

  After the second rust prevention step, the head 1 is finished as a product by painting part or all of the outer surface as necessary.

  As another embodiment of the present invention, the second rust prevention step may form the protective film 12a only on the outer surface 10 of the first member M1. This prevents the chemical conversion liquid from entering the hollow portion i into the head 1 and scrapes off the film 12d formed on the outer surface 16 of the second member M2 by, for example, blasting or polishing (film removal process). This can be achieved. In this case, for example, the opening 7h of the shaft insertion hole 7a is preferably closed.

  Further, the second rust prevention step is not limited to the above embodiment, and may be performed by a method different from the first rust prevention step. For example, even if the first rust-preventing step is a chemical conversion treatment, the second rust-preventing step can be performed by, for example, anodizing treatment.

  A wood-type golf club head was prototyped based on the specifications in Table 1, and the effects of the present invention were confirmed. As shown in FIGS. 1 to 4, each of the heads is a cast of Ti-6Al-4V having a plate-like first member made of a magnesium alloy disposed in the crown portion and an opening in the crown portion. It formed by joining the 2nd member which consists of goods. As the magnesium alloy, AZ-91 (Mg: about 90% by weight, Al: about 9% by weight, Zn: about 1% by weight), which is an Mg—Al—Zn alloy, was used.

Moreover, about the example which adhere | attached the 1st member and the 2nd member, the one-pack type epoxy adhesive (the product name "Scotch Weld (registered trademark of the company)" EW2010 manufactured by Sumitomo 3M Co., Ltd.) was used, The curing conditions were unified at a curing temperature of 120 ° and a curing time of 70 minutes. The chemical conversion treatment was performed by immersing in the next aqueous treatment liquid for about 5 minutes.
(Processing liquid)
3g / l KMnO4
1g / l NH4 VO3
In the second rust prevention step, Examples 1 and 2 treated the entire outer surface and inner surface of the head, but in Example 3, a protective film was formed only on the outer surface of the first member.
The test method is as follows.

<Salt spray test>
A 12 hour salt spray test with 5% NaCl solution was performed. After spraying with salt water, it was left in the atmosphere for 12 hours, and the surface of the first member was observed by visual inspection. The case where no rust was generated was indicated as “OK”. The thing which rust generate | occur | produced in part was set to "NG".

<First moisture resistance test>
Each test head was left in an oven at a temperature of 50 ° C. and a humidity of 90% for 10 days, and then the surface of the first member was visually inspected for rust. The case where no rust was generated was defined as OK.

<First durability test>
The same FRP shaft (MP-300 Flex R SRI Sports Co., Ltd.) was attached to each test head after the first moisture resistance test, and a 45-inch wood type golf club was manufactured as a prototype. Then, each test club was mounted on a swing robot, and a durability test was performed in which 3000 balls of golf balls (“everio” manufactured by SRI Sports Co., Ltd.) were hit continuously at a head speed of 50 m / s. In addition, the joint part of the 1st member and the 2nd member was visually confirmed every 100 shots, and the number of hit balls at the time when damage such as cracking or detachment occurred was examined. Those that were not damaged were accepted.

<Second moisture resistance test>
Each test club subjected to the first durability test was left in an oven at a temperature of 50 ° C. and a humidity of 90% for 10 days, and then the surface of the first member of the head was visually inspected for rust. It was. The case where no rust was generated was defined as OK.

<Second durability test>
A durability test was conducted in each of the test clubs subjected to the second moisture resistance test. The hitting condition is the same as in the first durability test.
Table 1 shows the test results.

  As a result of the test, only Comparative Example 1 advanced to the severest second durability test among Comparative Examples. However, in Comparative Example 1, a large number of rusts can be confirmed on the bonding surface of the first member peeled from the second member, and this caused a lack of bonding strength with the second member, leading to peeling. I can guess. On the other hand, it can be confirmed that the heads of the examples exhibit higher corrosion resistance and durability than the comparative examples.

It is a perspective view of the head of this embodiment. It is the AA sectional view. It is BB sectional drawing of FIG. FIG. 2 is an exploded perspective view of FIG. 1. It is the C section enlarged view of FIG. (A)-(B) are the fragmentary sectional views explaining the manufacturing method of a head. (A), (B) is a fragmentary sectional view of the head explaining the manufacturing method of the conventional golf club head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Golf club head 2 Face surface 3 Face part 4 Crown part 5 Sole part 6 Side part 7 Neck part 10 Outer surface 11 of 1st member Joining surface 12 of 1st member Protective film 15 Adhesive M1 1st member M2 Second member

Claims (8)

A plate-like first member made of a magnesium alloy, an opening in which the first member is disposed, and a recess formed in a step shape from the outer surface of the head around the opening, and the periphery of the first member A golf club head manufacturing method for manufacturing a golf club head having a hollow structure by joining at least a second member made of a non-magnesium alloy with a support surface on which a portion is placed ,
Prior to joining the first member and the second member, the first member has at least an outer surface facing the outer surface of the head and a joining surface joined to the second member. A first rust preventive step for forming a protective film for preventing corrosion of the member;
A joining step of joining the first member and the second member;
A polishing step of polishing the outer surface of the head including the joint between the first member and the second member so that the outer surfaces of the first member and the second member are flush with each other;
After the polishing step, including a second rust prevention step of forming the protective film on the entire outer surface of the first member and an inner surface facing the hollow portion of the first member. A method for manufacturing a golf club head, comprising:
The golf club head manufacturing method according to claim 1, further comprising a film removing step of removing the film adhered to the outer surface of the second member after the second rust prevention step.
The golf club head includes a neck portion having a shaft insertion hole to which one end of a shaft is attached,
The second rust prevention step includes a step of spreading a protective film forming treatment liquid from the opening provided in the shaft insertion hole of the neck portion 7 and communicating with the hollow portion to the hollow portion of the head. Item 3. A method for producing a golf club head according to Item 1 or 2 . Said first member, the manufacturing method of the golf club head according to any one of claims 1 to 3 is joined to the second member by an adhesive. 5. The method of manufacturing a golf club head according to claim 1, wherein a thickness t of the first member is not less than 0.4 mm and not more than 1.5 mm . The ratio (Sc / Sa) of the covering area Sc, which is the area of the first member covering the opening of the second member, to the total surface area Sa of the head is 0.3 or more and 0.9 or less. The method for manufacturing a golf club head according to claim 1, wherein: The first and second rust preventive steps include a chemical conversion treatment in which the first member is immersed in an aqueous electrolyte containing no chromium and containing vanadium acid for 5 minutes in a room temperature environment. A method for producing a golf club head according to claim 1. A golf club head having a height of the center of gravity of the head from the horizontal plane of 35 mm or less is manufactured by the method according to any one of claims 1 to 7 in a reference state in which the head is placed on the horizontal plane at a specified lie angle and real loft angle. A method for manufacturing a golf club head, comprising:

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