JP3056395B2 - Method of manufacturing hollow club head made of Ti alloy for golf club - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a hollow club head of a golf club using a Ti alloy, and more particularly, to a method of manufacturing a hollow club head material by a casting method or a forging method and a method of manufacturing the hollow club head. A method of appropriately adjusting the weight and thickness of the head by a simple method and producing a well-balanced club head at a low cost, and further casting using a β-type Ti alloy having a good diffusion property as a material. The present invention relates to a method for producing a hollow club head which can solve the problems caused when performing forging and forging, and can stably exhibit excellent hitting performance over a long period of time. The hollow club head of the present invention can be applied not only to hollow wood but also to hollow iron.

[0002]

2. Description of the Related Art Club heads of golf clubs are widely used from solid persimmons to hollow metals or carbons. In recent years, however, they can be expected to have a long flight distance due to their large moment of inertia. Hollow metal or carbon is becoming mainstream. Among these, stainless steel, A
It is preferable to use a product made of 1 alloy or Ti alloy.

[0003] Among metal club heads, a Ti alloy head has recently attracted particular attention.
This is due to the advantage that the i-alloy is lightweight and has high specific strength. In order to further enhance the feature, there is a tendency to shift to a so-called large head for the purpose of increasing the capacity of the hollow Ti alloy head to increase the repulsion and further increase the flight distance.

When such a Ti alloy hollow golf head is manufactured by casting or forging, the thickness of the thinnest portion is 1.5 to 1.8 m due to the relationship between the weight of the head and restrictions on the manufacturing process. / M, head capacity is 220 ~
The limit is about 230 cc. In this case, a large-capacity head having a capacity exceeding 230 cc or 230 c
To manufacture a head having a wide crown surface even if the head is smaller than or equal to c, the weight of the crown surface whose thickness is desired to be minimized in the head increases, and the head weight increases or the height of the center of gravity increases. A problem arises in that the balance as a whole deteriorates. Therefore, in order to further enhance the performance of a hollow head made of a Ti alloy, it is necessary to establish a technique capable of increasing the head capacity by thinning a desired portion of the head without impairing the balance of the entire head.

On the other hand, as a material for a hollow head made of a Ti alloy, an α-type titanium alloy has been widely used in the past, and for a case using a β-type Ti alloy, a cold press working method or a forging method is employed. However, there is no known club head that mentions the problems described below that occur when the β-type titanium alloy is used.

[0006]

SUMMARY OF THE INVENTION The inventors of the present invention have focused on the above circumstances, and a first object of the present invention is to impair the balance of a hollow golf head made of Ti alloy as a whole. In addition, it is an object of the present invention to establish a technique capable of increasing the capacity by reducing the thickness of a desired portion of the head and increasing the flight distance.

A second object of the present invention is to provide a method capable of selecting a β-type Ti alloy as a Ti alloy material and producing a club head having further excellent performance. This is because attention was paid to the fact that the β-type Ti alloy has excellent diffusibility, and it was expected that a further flight distance could be obtained by forming a hardened layer based on diffusion. However, there is a risk that the formation of a hardened layer may lead to cracking of the club head, and the probability of a manufacturing technique capable of enjoying only an increase in the flight distance without causing such cracking is cited as a second object.

[0008]

Means for Solving the Problems The structure of the manufacturing method according to the present invention, which can achieve the above-mentioned objects, is to provide a surface and / or a hollow club head material for a golf club formed by a casting method or a forging method using a Ti alloy. The gist is that the entire inner surface or at least a part of each surface is chemically polished to adjust the weight and thickness of the hollow club head material.

In carrying out the present invention, a β-type Ti alloy is selected as a material, and at least an inner surface of a face portion of the hollow club head material is chemically polished, so that oxygen diffusion during a casting process or a forging process is performed. By adopting a method of completely or partially removing the hardened layer of the inner surface based on the above, it is possible to obtain a β-type Ti alloy hollow club head with further excellent performance.

[0010]

[Function] The production of a general golf head using a Ti alloy material is performed following the procedure of heating and melting the Ti alloy material → casting to a predetermined sand mold → demolding and sand removal → sole welding → finishing polishing → painting. However, if the thickness of the hollow head material is excessively reduced in the casting step, particularly in the casting step, a casting defect occurs and causes a product defect. Even
Its thickness is limited to about 1.8 mm at most, and it is difficult to make it thinner. As a result, the Ti alloy hollow head material is generally heavy and the head capacity has to be reduced. As described above, the head weight as the final product increases and the height of the center of gravity increases. become worse.

[0011] Therefore, in order to solve these difficulties, it is necessary to grind the outer surface side of the cast material to reduce the thickness of a predetermined portion so as to reduce the weight and improve the balance. Since has a complicated curved surface, the grinding operation is very complicated and complicated, and a significant increase in product cost cannot be avoided. Moreover, in such a grinding process, only the outer surface of the hollow head can be ground, so that it is difficult to apply it to a large head by increasing the capacity.

In view of the above, various studies have been made in order to form a desired portion appropriately thin without causing the above-mentioned problems, to enable an increase in head capacity, and to achieve a reduction in the weight of the head and a further improvement in repulsion. As a result, the Ti
By adopting a method of chemically polishing the entire surface and / or the inner surface of the alloy hollow club head material or at least a part of each surface, it is extremely easy to adjust the weight and thickness of the hollow club head material. Knowing that the present invention can be performed, the present invention has been completed based on such knowledge.

Accordingly, in the present invention, the entire surface and / or at least a part of each surface of the hollow club head material formed by a casting method or a forging method using a Ti alloy is chemically polished to thereby form the hollow club head material. It is characterized by adjusting the weight and wall thickness.

In practicing the present invention, after forming a hollow club head material using a Ti alloy in accordance with a conventional method, the entire inner and outer surfaces of the material or a portion thereof particularly requiring thinning is subjected to a chemical polishing treatment. By employing a method of polishing (including pickling or electrolytic polishing), the thickness of the required portion can be easily reduced, and the inner surface can be easily polished, so that the head capacity can be easily increased. As a result, it is possible to avoid weight increase due to insufficient thinning and to avoid problems such as weight reduction and an increase in the position of the center of gravity. It is possible to obtain a Ti alloy club head having high excellent performance.

In the hollow golf club head, the position of the center of gravity is lowered as much as possible, and the face, sole, heel, etc., on which the external force acts, are relatively high in strength. It is preferable that the crown and the back face, which are hard to be affected by external force, are relatively thin, but according to the present invention, the face portion, the sole portion, the heel portion, and the like are preceded by a chemical polishing treatment. If it is masked with an acid-resistant paint or the like and the chemical polishing treatment liquid acts only on the inner surface and / or outer surface of the crown or the like that needs to be thinned, only the relevant portion is selectively polished. It is possible to reduce the thickness and the weight associated with the reduction of the thickness, and if the polishing portion is set on the inner surface side of the hollow portion, the head capacity can be increased at the same time.

The type of the chemical polishing treatment liquid used in the present invention is not particularly limited, and it is essential that the chemical liquid is capable of sequentially dissolving the Ti material from the surface side without deteriorating the Ti alloy material. Generally, a strong acid mixed aqueous solution of nitric acid and fluoric acid is used. Among them, a mixed aqueous solution having a nitric acid concentration of about 10 to 20% by weight and a fluoric acid concentration of about 10 to 20% by weight is recommended as the most preferable one. However, in the present invention, the type of these chemical polishing liquids is not limited at all,
Depending on the type of alloy, the treatment temperature, and the combination with the electrolytic polishing treatment, one or more of other acids such as sulfuric acid, hydrochloric acid, hydrofluoric acid, and oxalic acid can be used as appropriate.

As described above, the chemical polishing treatment according to the present invention can be applied to the entire inner and outer surfaces of the club head. However, the outer surface is stopped slightly to clean the surface, and the inner surface is mainly used. If the polishing treatment is performed, the effect of enlarging the capacity of the hollow portion can be increased at the same time, and it is preferable that the polishing treatment on the inner surface side of the crown portion as described above is particularly effective in reducing the weight and optimizing the position of the center of gravity. This is advantageous.

By the way, the chemical polishing treatment of the present invention is as follows.
Since the main focus is on reducing the weight and adjusting the weight by making the hollow head thinner, and further expanding the head capacity, there is no restriction on the type of Ti alloy used, and ordinary α-type Ti alloys and β-type Ti alloys are used. The present invention can be applied to all processes for manufacturing a hollow club head made of an alloy. Further, in the present invention, since the head capacity can be increased at the same time by applying to the polishing treatment on the inner surface side of the hollow portion for the above,
In particular, the advantage is effectively exhibited in the production of a large club head, but it can of course be utilized in the production of a club head of a normal size.

However, the present inventors have further studied and found that if the above-mentioned chemical polishing method is adopted, Ti
The following defects observed when a β-type Ti alloy was selected as the alloy were suppressed as much as possible, and it was confirmed that a hollow club head with a further increased flight distance was obtained. A description will be given of a case where a Ti alloy is used.

The β-type Ti alloy is a β-stabilizing element M
o, V, Nb, Ta (above all solid solution type) or Fe,
Cr, Mn, Co, Ni (above eutectoid type), Sn and Z
Although those containing r are typically shown, Al which is an α-stabilizing element may be added to an age hardening type β alloy. Accordingly, non-limiting examples of particularly typical β-type Ti alloys include: Ti-13V-11Cr-3AlTi-8Mo-8V-2Fe-3Al Ti-3Al-8V-6Cr-4Mo-4Zr Ti-11 .5Mo-6Zr-4.5SnTi-15Mo-5ZrTi-15Mo-5Zr-3AlTi-15V-3Al-3Sn-3Cr and the like. It goes without saying that the compounding amounts of the alloying elements in the above-described exemplary alloys can be slightly increased or decreased, respectively.

As a method of manufacturing a club head using the above-mentioned β-type Ti alloy, a casting method will be first described. As a casting mold, a zirconia sand mold is generally used. The oxygen atoms therein diffuse into the casting and the diffusion layer hardens. And it is expected that the hardened layer formed on the outer surface of the face part will exert an excellent repulsive force at the time of hitting ball and act in the direction of increasing the flight distance, and according to the actual results of various experiments, it is very good A great flight distance.

However, according to further studies, since the cast club head has a hollow structure, the inner surface of the club head protrudes greatly toward the inner surface of the hollow when a ball is hit, and excessive tensile stress is repeatedly applied to the surface. As a result, it has been found that fine cracks occur and give serious quality defects to the club head. Although the outer side of the club head was subjected to a large compressive stress at the time of hitting the ball, the hardened layer was strong against the compressive stress and no crack was generated on the outer side of the face.

Also, the case of forming by forging was examined. Particularly, under the high heat conditions during the hot forging process, oxygen atoms in the atmosphere diffused deeply into the surface of the forged product, and the same as the cast product. (The flight distance becomes longer, but cracks occur on the face inner surface side).

Then, when the hardened layer on the inner surface side of the face was studied, the hardened layer grew considerably thick and became brittle with little ductility because the β-type alloy had high diffusivity as described above. Therefore, it was suggested that it is necessary to remove the hardened layer on the inner face side of the face in order to prevent the occurrence of the crack. However, with regard to the means for removing the hardened layer, it was considered difficult to apply polishing by mechanical means since the face inner surface side is located at the back of the cavity. Considering the use of the chemical polishing method as described above, when the hardened layer on the inner surface of the face was subjected to chemical polishing, it was found that only the desired portion of the hardened layer could be removed in a short time. Although the hardened layer removal at this time may be performed over the entire width direction and depth direction of the face inner surface,
As long as the crack due to the inner side protrusion at the time of hitting can be prevented, it can be stopped at an arbitrary size and an arbitrary depth. Also, if the hardened layer is removed from a portion adjacent to the face, for example, a transition portion to the crown portion, good crack resistance can be exhibited even in a use method where a hit is bad.

As for the hardened layer on the outer surface of the face,
From the viewpoint of increasing the flight distance due to curing, protection from the chemical polishing is desired, but slight removal does not adversely affect the essence of the present invention. Regarding each part other than the face part, for example, the crown and the back face, the presence or absence of polishing is not important.

As described above, if the chemical polishing method of the present invention is used for removing the hardened layer on the inner surface side of the face, it is possible to reduce the thickness of the hollow wall and to reduce the weight, and furthermore, to increase the capacity of the internal space. In addition, it is possible to simultaneously enhance the crack resistance of the face portion. Therefore, when carrying out this method, it is advantageous to set the polishing position so that the polishing liquid acts on the inner face of the face where the hardened layer needs to be removed and on the inner face of the crown where thinning is desired most.

It is necessary to carry out the chemical polishing method before the sole welding of the club head, and the process after the sole welding is not particularly different from that of the conventional method. Age hardening treatment commonly used in Ti alloy products can be arbitrarily employed in the present invention.

[0028]

EXAMPLES Next, the structure and operation and effect of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and the present invention is applicable to the above and following points. It is, of course, possible to carry out the present invention with appropriate modifications within the scope of the invention, and all of them are included in the technical scope of the present invention.

Example 1 Ti-6Al-4V was melted, and a club head material was cast using a zirconia sand mold (crown thickness:
1.8mm, weight 205g, head capacity: 180c
c). Two obtained castings are prepared, and using the pickling solution of the following formulation, (1) the entire inner and outer surface polishing treatment, and (2) the entire surface masking with an acid-resistant paint and the entire surface polishing treatment only on the inner surface side. In each case, a chemical polishing treatment was performed with a target weight of 170 g and a target thickness of the crown portion of 1.3 mm. As a result, in the above (1), the target weight and the crown thickness were adjusted in about 2 minutes, and in the (2), the target weight and the crown thickness were adjusted in about 5 minutes. (2)
In the above method, the polishing process requires a slightly longer time. However, in this method, only the inner surface of the hollow portion is polished without causing the polishing liquid to act on the outer surface of the head. It can be seen that the reduction in the size does not occur, and therefore, it is more effective for manufacturing a large head. (Polishing liquid formulation) 70% HF: 40 g 67.5% HNO ₃ : 40 g Water: 120 g Liquid temperature: 30 to 60 ° C.

Example 2 Ti-15V-3Cr-3Sn-3Al was dissolved, and a club head (face thickness: 3.0 mm and 3.5 mm) was cast using a zirconia sand mold. When the hardness distribution of the section in the face thickness direction of the cast product having the face thickness of 3.5 mm was examined, the result shown in FIG. 1 was obtained. As can be seen from the figure, a region having a thickness of 220 to 240 μm (oxygen-rich layer) due to the diffusion and penetration of oxygen.
Showed high hardness.

Next, the above cast product was formulated according to the following formulation (A),
Chemical polishing was performed with the pickling solution of (B). The processing temperature is 43 to 5
At 7 ° C., both sides of the face were chemically polished in the case of using the prescription (A), and the outside surface of the face was protected with an acid-resistant paint in the case of using the prescription (B). Since the protection was removed, only the inner surface was chemically polished. The time required for the chemical polishing was 80 to 90 seconds, and the cured layer was removed over a depth of 250 μm. Therefore, in the case of using the prescription (A), a total of 500 μm
In the case of using the prescription (B), 250 μm was removed only on the face inner surface side.

Formulation (A) 70% HF: 75 g 67.5% HNO ₃ : 1078 g Urea: 31 g Benzoic acid: 4.9 g Sodium nitrate: 12 g Phosphoric acid: 9.6 g To 80 parts by weight of the above mixture was added 20 parts by weight of water. 1
00 parts. Formulation (B) 70% HF: 150 g 67.5% HNO ₃ : 200 g Water: 650 g

(Test Example) A club head (Example) obtained by chemically polishing both sides of the face with the pickling solution of the formula (A),
Using a club head (comparative example) manufactured without performing chemical polishing, a test hitting experiment was performed by a robot. Test conditions Ball: Large size 2 pieces Head speed: 50 m / s Hit position: Face center Club used: No. 1 wood test result

[0034]

[Table 1]

As is evident from the results in Table 1, the club head produced by the method of the present invention exhibited excellent crack resistance against repeated hit balls. Also, a good flight distance could be obtained by the action of the elastic force.

In addition, when the inventors tried a test using a club head obtained by chemically polishing only the inner surface of the face with the pickling solution of the formula (B), the repelling action of the face surface resulted in a superior flying performance over the conventional product. The distance was shown, and no cracking of the face was observed.

[0037]

The present invention is configured as described above,
When manufacturing a hollow club head using an i-alloy, by processing a material formed by casting or forging by a chemical polishing method, it is possible to easily reduce the thickness of a portion required to be reduced by a simple operation. As a result, the weight can be reduced without adversely affecting the center of gravity and balance of the head, and the repulsive force can be easily increased by expanding the head capacity.
It has become possible to provide an i-alloy hollow club head.
Further, when the present invention is applied to the production of a club head using a β-type Ti alloy, it is possible to provide an excellent β-type Ti alloy club head which does not cause a crack in the face.

[Brief description of the drawings]

FIG. 1 is a diagram showing a hardness distribution of a cross section in a face thickness direction of a cast club head.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-2267 (JP, A) JP-A-2-191474 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A63B 53/04

Claims (2)

(57) [Claims] 1. A hollow club head material for a golf club formed by a casting method or a forging method using a Ti alloy, wherein the entire surface and / or at least a part of each surface of the hollow club head material for a golf club is chemically polished. For controlling weight and thickness of a golf club
A method for manufacturing an alloy hollow club head. 2. Using a β-type Ti alloy as a material and chemically polishing at least the inner surface side of the face portion of the hollow club head material, the inner surface side based on oxygen diffusion during a casting process or a forging process. 2. The method according to claim 1, wherein the hardened layer is entirely or partially removed.