JPH10155942A - Golf club head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head by which the flexibility of the head (Young's modulus) can be adjusted in a wide range while the characteristic of a titanium alloy such as light weight, large specific strength and so on are kept, and which is more excellent in respect of function than the conventional head made of a titanium alloy. SOLUTION: The material of a part of a golf club head is crystallized titanium boride, deposited titanium boride, or a titanium alloy containing both of the above. Preferably the alloy contains 0.001wt.% to 5wt.% boron (B). Further 10wt.% or less aluminium (Al) and the other alloy components may be contained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention makes use of the properties of a titanium alloy having a high specific strength, and furthermore, from a low Young's modulus close to a conventional titanium alloy head to a high Young's modulus close to a stainless steel head. Golf club head that can have a Young's modulus (hereinafter simply referred to as “head”
Described).

[0002]

2. Description of the Related Art Among golf clubs, the head of what is called a wood club has conventionally been made of wood (persimmon material called persimmon). However, in recent years, from the depletion of natural persimmon, metal products that are rich in raw materials and can be produced industrially stably, that is, stainless steel, titanium alloy,
Heads made of aluminum alloys and the like have become mainstream.

[0003] A metal head is characterized in that the center of gravity can be arbitrarily changed by making the inside hollow for a wood club. Therefore, since it has an excellent function in terms of being able to hit a ball farther and more accurately than a wooden head, it has become very popular. Also, the design of the head of the iron club can be diversified, and heads of various shapes such as a cavity back have been put to practical use.

[0004] The above-mentioned metal heads have different characteristics as described below depending on the type of metal (alloy) as a material.

[0005] The most popular stainless steel head material is JIS SUS 630.
However, since the specific gravity is as large as about 7.8, the volume of the head and the length of the shaft are limited. Also, the Young's modulus
Since it is as high as 200 GPa, the deflection when hitting the ball is small and the ball is straight.

The most popular material for titanium alloy head material is 6Al-4V
-Ti (a titanium alloy containing 6% of aluminum and 4% of vanadium). This is because the specific gravity is as small as 4.4,
The volume of the head can be enlarged, and the position of the center of gravity and the design are rich. Further, the shaft can be lengthened by reducing the head weight, and the flight distance of the ball is increased by increasing the moment of inertia. Also, since the Young's modulus is as low as 116 GPa, it is advantageous when the deflection at the time of hitting the ball changes the trajectory of the ball.

Recently, a head using a titanium alloy has been developed.
It is becoming widespread, especially for golfers with low head speeds, such as beginners, the elderly, and women. Incidentally, JP-A-5-11
Japanese Patent No. 1554 proposes a head using a superelastic Ni-Ti alloy, and the alloy has a Young's modulus lower than that of the titanium alloy, and is about 80 GPa. With such an alloy head, a feeling close to that of wooden wood can be obtained, but since the Young's modulus is too low as described above, golfers with high head speed such as advanced players like tour professionals However, there is a problem that satisfactory performance cannot be obtained.

For an advanced player, ie, a golfer who has the technology and power to fly the ball far without relying on the deflection of the head, the one with the higher rigidity of the head fixes the angle at which the head hits the ball and applies the force directly. It is convenient to communicate. For such golfers, a head having a high Young's modulus close to stainless steel is suitable. On the other hand, a beginner or the like is desirably a head having a low Young's modulus and easy bending like a conventional titanium alloy. That is, it is ideal if heads having various Young's moduli (flexibility) can be manufactured according to the golfer's skill.

[0009] However, hitherto, no head has been able to meet such demands, so that only stainless steel or an existing titanium alloy could be selected.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to maintain the excellent properties of a titanium alloy, such as specific strength (ratio of strength to weight), as a lightweight structural material, and particularly to the ease of bending of a head. Can be set to a wide range,
It is an object of the present invention to provide a head that can have an optimal function according to the skill of a golfer.

[0011]

SUMMARY OF THE INVENTION The present invention provides a golf club head characterized in that at least a part of the material is a titanium alloy containing crystallized titanium boride or precipitated titanium boride or both. Is the gist.

[0012] Titanium boride is finely dispersed in the matrix of the alloy by crystallization when the melt of a titanium alloy containing B (boron) solidifies, or by precipitation during cooling after solidification. The amount of such crystallized titanium boride or precipitated titanium boride can be basically adjusted by the amount of B added.

The material forming at least a part of the head of the present invention is a titanium alloy. The alloy includes “crystallized titanium boride and / or precipitated titanium boride” (hereinafter collectively referred to as “crystallized / precipitated titanium boride”). Therefore, the alloy must contain enough B to produce crystalline and precipitated titanium boride. As described later, the content of B is 0.001% by weight.
The content is desirably at least 5% by weight.

There are no particular restrictions on the alloy components other than B.
Pure titanium may be added with only B, and besides,
For example, up to 10% by weight of aluminum (Al), up to 25% by weight of vanadium (V), up to 6% by weight of tin (Sn), up to 12% by weight of chromium (Cr), up to 16% by weight of molybdenum (Mo) , 6% by weight or less of iron (Fe), and 0.2% by weight or less of oxygen (O). A small amount of Zr,
Si, Mn, Nb, Ta, Pd, Co, Ni, Bi, and C may be contained. However, it is desirable that nitrogen (N) and hydrogen (H) are as small as possible. B may be added to an existing titanium alloy containing one or more of these alloy components to produce crystallized / precipitated titanium boride.

[0015]

FIG. 3 is a Ti-B binary phase diagram (JL
Murray, PKLiao, and KESpear, 1987). As shown, since B hardly forms a solid solution with titanium, almost all of B added to titanium crystallizes or precipitates as titanium boride (TiB) during solidification and cooling. The crystal / precipitated titanium boride has a function of improving the Young's modulus of the titanium alloy. Titanium boride has a Young's modulus of 500 G
Above Pa, it is much higher than titanium and improves the Young's modulus of titanium alloys according to the composite rule proportional to the particle volume fraction.

FIG. 1 shows the effect of the B content on the Young's modulus. This is a test result of an as-cast material in which various amounts of B are added to pure titanium (JIS type 2). As shown, the Young's modulus increases in proportion to the B content.
This is because the content of TiB is increasing as shown on the horizontal axis in FIG. The relationship between the Ti content and the TiB content is approximately TiB (% by weight) = 5.43 × B content (% by weight).

When the content of B is 5% by weight or more, ductility (toughness) is reduced, and cracking may be caused by casting solidification, hot working, welding, or the like. Therefore, the B content is preferably set to 5% by weight or less. If the B content is less than 0.001% by weight, the amount of crystallized and precipitated titanium boride is insufficient.
Since the improvement of the Young's modulus cannot be expected, the B content is preferably set to 0.001% by weight or more. More preferably, it is 0.01% by weight or more.

As can be seen from FIG. 1, by changing the B content, the amount of dispersion of the crystallized and precipitated titanium boride can be adjusted to obtain an alloy having a desired Young's modulus. For example, B is added to pure titanium (Young's modulus: 108.5 GPa),
When the content is 5% by weight, the Young's modulus is about 200 GPa, the same as that of stainless steel, and the head can be made of a titanium alloy and has little deflection like stainless steel. Also, keep the content of B at about 1% by weight,
A head having a Young's modulus of about 120 GPa and a flexibility similar to that of an existing 6Al-4V titanium alloy head can be used. That is, it can be adjusted according to a golfer's requirement, from the flexibility of a conventional stainless steel head to the flexibility of a conventional titanium alloy head.

The specific gravity of the titanium alloy containing B is about 4.5 and the strength (tensile strength) is more than 1000 MPa, and the high specific strength, which is an advantage of the titanium alloy, is still maintained. There is no problem in the design.

The characteristics of the head of the present invention can be changed by the addition of another alloying element as described above in addition to B. Hereinafter, Al and V which are typical additive elements of the titanium alloy will be described.

1) Regarding Al FIG. 2 is a diagram showing the influence of the Al content and the V content on the Young's modulus. This test, like the test for B above, is based on an as-cast material obtained by adding Al or V to pure titanium (JIS type 2).

Al has the function of increasing the Young's modulus by solution hardening, and can be added to adjust the Young's modulus. However, if its content exceeds 10% by weight, the ductility (toughness) is increased.
Decrease. Therefore, the content of Al is preferably limited to 10% by weight or less. In consideration of the balance between strength and ductility, the Al content is more preferably 0.1% by weight or more and 8% by weight or less.

2) V As shown in FIG. 2, V is an element that lowers the Young's modulus, but is a β-phase stabilizing element, and improves heat treatment properties, hot workability and cold workability. Contribute to improvement. Even when V is added to take advantage of these effects, the lowered Young's modulus can be recovered by adding B or further adding Al. However, excessive addition of V diminishes the effect of improving the Young's modulus of B or Al.
Even when it is added, its content is desirably 25% by weight or less.

The above-mentioned titanium alloy containing the crystal / precipitated titanium boride and having a controlled Young's modulus may be used as a material for the entire head, or may be used for only a part of the head, for example, only the face portion. Good. By doing so, it is possible to design a head having various characteristics and a head corresponding to delicate requirements.

Next, a method of manufacturing a golf club head according to the present invention will be described.

I. In the case of manufacturing by the casting method A desirable example of the manufacturing by the casting method includes the following steps.

A mold for the head is made, and a wax model is made with this mold.

A ceramic mold is made using a wax model.

The ceramic mold from which the wax has been removed is fired.

Using a water-cooled crucible in a vacuum, the raw materials whose components have been adjusted are arc-melted to prepare a molten titanium alloy.
At this time, to uniformly disperse the titanium boride in the matrix, aluminum boride or iron boride having a low melting point (2000 ° C. or lower) is used rather than mixing titanium boride having a high melting point (about 3000 ° C.) as it is. Is desirably added to the molten metal to crystallize and / or precipitate titanium boride during solidification and / or cooling. Further, an ingot or a forged material in which titanium boride is already uniformly dispersed can be used as a melting raw material.

The molten metal is poured into a ceramic mold.

With the above steps, a casting head is completed. Thereafter, post-processing such as polishing and painting is performed as necessary.

Ii. In the case of manufacturing by forging method For example, it is desirable to adopt the following steps.

A titanium alloy ingot in which titanium boride is dispersed is melted from the adjusted raw material by the VAR method. Regarding the method of dispersing titanium boride, a low melting point aluminum boride or iron boride is added and titanium boride is added during solidification and / or cooling, rather than mixing the high melting point titanium boride directly into the VAR electrode. Crystallization and / or
Alternatively, a precipitation method is preferable for uniformly dispersing the titanium boride in the matrix.

A plate is formed by hot forging and hot rolling.

The processed structure is erased by heat treatment.

The oxide scale on the surface is removed by shot blasting, pickling and grinding.

Each part of the head (each part of the face, sole, and crown) is manufactured by machining.

The head is assembled by welding.

The forging head is completed by the above steps. Thereafter, post-processing such as polishing and painting is performed as necessary.

In the case of an alloy that can be cold-forged and cold-rolled, these processes may be performed during the above steps. Further, when the strength can be increased and the Young's modulus can be adjusted by aging treatment, an aging treatment step may be provided after the head is assembled by welding.

As described above, in the head of the present invention, the alloy containing the crystallized / precipitated titanium boride may be used for all or only a part of the alloy. Further, the head may be used for all or a part of the head by changing the content of the crystal and precipitated titanium boride in each part of the head. Such a head may be manufactured for each part by a casting method or a forging method, and each part may be assembled by welding to form a head.

The head according to the present invention includes not only a head for a wood club but also a head for an iron club.

[0044]

EXAMPLES Table 1 was prepared using titanium sponge, granular aluminum, granular vanadium, and granular aluminum boride as raw materials.
An alloy having the chemical composition shown in Table 1 was produced by a vacuum arc melting method and cast into a wood club head of a titanium alloy containing crystallized and precipitated titanium boride by a lost wax precision casting method.

The head has a face portion with a thickness of 3 mm, other portions with a thickness of 1.2 mm, and a volume of about 260 cc.
For comparison, a 6Al-4V-Ti alloy and SUS 630 stainless steel were used as raw materials and a head having the same shape was cast in the same manner. Using a test piece prepared by the same casting method as for the head for each alloy, the Young's modulus was measured by the resonance method, and the tensile strength and elongation were measured by a tensile test (JIS No. 10 subsize, φ6.25 round bar test piece). A measurement was made. The results are also shown in Table 1.

[0046]

[Table 1]

Comparative Example 1 is a head made of a 6Al-4V-Ti alloy, which is the most common of conventional titanium alloy heads, and has a low Young's modulus of 116 GPa and is easy to bend. Comparative Example 2 is the most common of the conventional stainless steel heads.
SUS 630 steel head with a high Young's modulus of 200 GPa and low deflection.

Examples 1 to 5 are heads made of titanium boride dispersed alloy. By adjusting the amount of titanium boride, the Young's modulus can be set to any value between about 130 GPa and about 190 GPa, and it is clear that a head having a desired flexibility can be obtained according to the characteristics of the golfer. is there. Among these, the examples (from the examples) using a titanium alloy in which the contents of B and Al are in the desired ranges have an elongation of 8% or more and show excellent characteristics.

[0049]

According to the present invention, it is possible to easily adjust the Young's modulus of the head, which has been difficult so far. Therefore, Young's modulus, which cannot be obtained with a conventional metal head, for example,
A titanium alloy head having a Young's modulus between 110 GPa and 200 GPa is obtained. That is, it is possible to cope with a wide range of characteristics required for the head.

[Brief description of the drawings]

FIG. 1 is a graph showing the effect of the B content on the Young's modulus of a titanium alloy.

FIG. 2 is a diagram showing the influence of Al content and V content on the Young's modulus of a titanium alloy.

FIG. 3 is a Ti-B binary phase diagram.

Claims (3)

[Claims] 1. A golf club head wherein at least a part of the material is a titanium alloy containing crystallized titanium boride, precipitated titanium boride, or both. 2. The golf club head according to claim 1, wherein the titanium alloy is a titanium alloy containing 0.001 to 5% by weight of boron. 3. The golf club head according to claim 1, wherein the titanium alloy is a titanium alloy containing 0.001 to 5% by weight of boron and 10% by weight or less of aluminum.