JPH09322951A - Head for golf club - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head for golf clubs having an excellent carry characteristic by noticing the compsn. and structure of a titanium alloy in order to take advantage of the material characteristics of the titanium alloy to the max. possible extent. SOLUTION: This head for golf clubs is produced by integrally and precisely casting a hollow titanium alloy golf club head body having an aperture at its sole surface, pressing the sole cap of the titanium plate aligned to the aperture and sealing this golf club head to the sole cap. In such a case, the golf club head body is produced by precisely casting the titanium alloy contg. molybdenum at 0 to 10 equiv. and controlling the cooling time in the as-cast state until 300 deg.C is attained right after the casting to 20 to 60 minutes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf club head in which a hollow golf club head body having a cavity therein is formed from a titanium alloy.

[0002]

2. Description of the Related Art A conventional golf club head is mainly formed of persimmon, an aluminum alloy, or an iron alloy such as carbon steel or stainless steel. More recently, a titanium alloy has attracted attention as a golf club head. And the accompanying α + β type Ti-6% Al-4% V alloy and β
Club heads made of titanium alloys such as molds of Ti-15% V-3% Al-3% Cr-3% Sn have been used.

From the viewpoint of the degree of freedom in designing the shape of the head, these titanium alloy golf club heads are generally hollow having an opening in the sole surface as described in Japanese Patent Publication No. 7-112498. The golf club head body of titanium alloy is precision-cast integrally, a sole cover of a titanium plate corresponding to the opening is manufactured by press working, and the golf club head body is manufactured by a method of sealing with the sole cover. And various shapes are designed.

By the way, it is important for the above-described hollow golf club head made of a titanium alloy to have a great flight distance characteristic. To this end, not only the design of the head shape but also the material of the head are sufficient. It is necessary to consider. However, the above-mentioned hollow head cast by titanium alloy is selected only from the topicality and novelty of the use of titanium alloy, and takes full advantage of the inherent material properties of titanium alloy. Is difficult.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention focuses on the composition and structure of a titanium alloy in order to maximize the material properties of the titanium alloy, and provides a golf club head having excellent flight distance characteristics. The purpose is to provide.

[0006]

Means for Solving the Problems Titanium alloys are roughly classified into α, α + β and β-type alloys according to the type of phase that appears at room temperature. Among them, the β-type alloy is excellent in heat treatment properties, so that the mechanical properties can be improved by changing the quantitative ratio, shape, distribution and size (structure morphology) of α and β phases.

[0007] The flight distance characteristic of a golf head is attributed to the repulsive force of the head, and the repulsive force is considered to be closely related to the mechanical properties of the material. Therefore, it is presumed that the flight distance characteristics can be improved by using a β-type alloy as a golf head material and performing heat treatment. Data on heat treatment in the field of titanium and titanium alloy castings are available from Ti-6% Al-4% V alloy (α
+ Β type alloy)
Nothing is known about cast β-type alloys.

[0008] Casting is a process utilizing a phase transformation from liquid to solid, and this process always includes a cooling step from solidification to room temperature. Therefore, the cooling process of the casting after casting is regarded as a heat treatment, and if it is used properly, there is no need for a heat treatment process for control to create a structure that improves the flight distance characteristics of the product in the golf head casting process. It is presumed that it becomes. In other words,
If the structure of the titanium alloy casting can be controlled by utilizing the cooling process of the casting after casting, the flight distance characteristics of the golf head can be improved by the cooling condition in the as-cast state when casting the shape of the golf club head It is thought that it is possible to create an alloy structure to be made. In addition, there may be a β-type titanium alloy composition having a desirable structure for increasing the flight distance characteristics of the golf head under the above-mentioned as-cast cooling condition.

Therefore, the inventors of the present invention first cast a golf club head from a β-type titanium alloy, and change the cooling condition in the as-cast state at that time, and the change in the structure in each case changes the golf head. Experiments were carried out to determine how it affects the flight distance characteristics of, and then the flight distance characteristics of the as-cast state of the golf heads cast from β-type titanium alloys having various compositions were compared. As a result, it has been found that the composition of the β-type titanium alloy showing a structure in which the flight distance improves under the cooling conditions of the as-cast state is such that the molybdenum equivalent is in a range including 0 to 10, and further, the molybdenum equivalent is 0 to 10. Immediately after casting when casting a golf head with β-type titanium alloy
Cooling time in the as-cast state until the temperature reaches 20 ° C.
It was found that a 60-minute range would result in a good aging precipitate structure in which a fine α-precipitated phase was dispersed in the β-phase. By manufacturing a hollow golf head from these titanium alloys by casting, The present invention has succeeded in developing a golf club head capable of greatly improving the flight distance as compared with a titanium alloy.

Although there are many elements that make up various β-type titanium alloys, recently, the molybdenum equivalent (Mo eq. = Mo% +0.67) has been used as a standard for classifying β-type titanium alloys.
V% + 0.44W% + 0.28Nb% + 0.22Ta% + 2.9Fe% + 1.6Cr% −
Al%) is often used (where% represents the weight percentage of each element).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) A golf head (a head volume of 270 cc) made of a Ti-10% V-2% Fe-3% Al alloy was manufactured by the following casting procedure. In this production, a vacuum and pressure frequency induction melting furnace was used for melting. First, after preheating titanium sponge in a lime crucible in a vacuum, argon was introduced into the furnace at about 1.5 atm, and after the titanium sponge was dropped, a vanadium chip, electrolytic iron and aluminum ingot were added. Next, the titanium alloy was centrifugally cast into a zirconia ceramic shell mold while keeping the melting output and the molten metal holding time after melting down. Thereafter, the mold was separated and chemically polished, and an industrial pure titanium sole lid manufactured in advance by a warm press was sealed to the golf head body by TIG welding in an argon atmosphere, and finally finished by mechanical polishing.

The golf club head made of the Ti-10% V-2% Fe-3% Al alloy thus manufactured was heated at a temperature of 75 Pa under a vacuum of 0.01 Pa.
After maintaining at 0 ° C. for 60 minutes, the golf club head was cooled by forced convection of argon.

As shown in FIG. 1, various experiments were conducted by changing the relationship between the temperature and the time at the time of cooling by changing the flow rate of argon. As a result, as shown in FIG. As shown in (a) to (d), the following microstructure was obtained on the face surface of the golf club head body.

That is, when rapidly cooled as shown by cooling 1 in FIG. 1, a single phase structure of β equiaxed crystal as shown in FIG. 2A is obtained. When cooled slowly as shown in FIG. 4, a needle-like mixed structure of α and β as shown in FIG. 2D was obtained, and a precipitated phase of α was obtained along the old β crystal grain boundary. .

Further, in the cooling 2 and the cooling 3 in which the cooling time in the middle of the cooling 1 and the cooling 4, that is, the cooling time in the as-cast state until reaching 300 ° C. is between 20 minutes and 60 minutes, As shown in (b) and (c) of FIG. 2, both are obtained as a structure (aged-out structure) in which β acicular crystals of α are uniformly dispersed in the equiaxed β crystals. In Cooling 3, in which the cooling time was slower than that in Example 1, a crystal in which the acicular equiaxed crystals of α were coarsened was obtained.

Each of the golf heads manufactured as described above is attached with a carbon shaft to assemble a golf club, and the results of a golf ball flight distance test performed by a robot are shown in Table 1 below.

[0017]

[Table 1]

In Table 1, condition A, condition B, condition C,
Condition D is that the head speed is 35 m / s and 40 m, respectively.
/ s, 45 m / s, 50 m / s, each corresponding to a woman, ordinary person, smasher, professional equivalent.

As shown in Table 1, it can be seen that the flying distance characteristics of the cooling 2 and the cooling 3 are superior to the cooling 1 and the cooling 4 even at the head speed of each condition. Therefore, in order to improve the flight distance characteristics of the golf head,
It is necessary to cool the titanium alloy at the cooling rate of the casting of cooling 2 and cooling 3 as shown in FIG. 1 to obtain an aging structure as shown in (b) and (c) of FIG. Conceivable.

(Embodiment 2) Next, golf heads (having the same shape as in Embodiment 1) made of various titanium alloys shown in Table 2 below are manufactured by the same precision casting as in Embodiment 1 above.
At this time, the cooling time in the as-cast state was set to 300 ° C. immediately after casting.
20 minutes to 60 minutes (cooling 2 in the first embodiment).
And the state of cooling 3), and the structure of the face surface of the golf head body made of each titanium alloy was observed.

[0021]

[Table 2]

As a result, in the Ti-6% Al-4% V alloy, the structure showed a mixed structure of α and β, which was similar to the state of cooling 4 ((d) in FIG. 2). In addition, Ti-10% V-2% Fe-3% Al
For Ti-5% Al-2% Cr-1% Fe alloy, (b) and (c) in Fig. 2
As shown in (1), a structure in which acicular equiaxed crystals of α were uniformly dispersed in β equiaxed crystals (aged precipitation structure) was obtained. Ti-15% V-3% Al
The -3% Cr-3% Sn alloy had a β phase equiaxed single phase structure as shown in FIG. In Table 2, the unit is% by weight, and the balance is titanium (Ti).

A golf club was assembled by attaching a carbon shaft to the golf head produced by casting each of the titanium alloys manufactured as described above, and a flying distance test of a golf ball was performed by a robot. The experimental results shown in Table 3 below were obtained.

[0024]

[Table 3]

As is evident from the experimental results in Table 3, the molybdenum equivalent (Mo eq.), Which became an age-expanded structure in the as-cast state.
Was in the range of 0 to 10, and the flight distance of the golf head made of a titanium alloy was much larger than that of other titanium alloys. The conditions A, B, C and D are the same as the head speed conditions shown in Table 1 above.

[0026]

According to the present invention, the titanium alloy golf club head formed by casting has a molybdenum equivalent of 0 to 10 of the titanium alloy, and has a cooling rate of the casting when casting a golf club head having the shape of the main body. Since the aging structure is used, the flight distance of the golf head can be remarkably improved as compared with the conventional product, and can greatly contribute to score making. Further, since this golf club head is manufactured by casting, it is suitable for a golf head shape design having a large degree of freedom in the club shape and a long flight distance.

[Brief description of drawings]

FIG. 1 is a diagram illustrating cooling curves of a golf head when cooled from 750 ° C. under forced convection of argon.

2 (a), (b), (c), and (d) show schematic diagrams of the microstructure of a casting obtained corresponding to each cooling curve of FIG. 1. FIG. Cooling 1
2 (b) is a microstructure obtained in the state of cooling 2 in FIG. 1, and FIG. 2 (c) is a microstructure obtained in the state of cooling 3 in FIG. Microstructure,
FIG. 2D shows the microstructure obtained in the state of cooling 4 in FIG.

Front page continuation (72) Inventor Yoshinori Terada 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Incorporated company Kobe Steel Ltd. Tokyo headquarters (72) Inventor Takashi Sato 2-20 Chigaoka, Natori-shi, Miyagi No. 9

Claims (1)

[Claims] 1. A golf club head, wherein a hollow titanium alloy golf club head body having an opening on a sole surface is precision-cast integrally and a titanium plate sole lid corresponding to the opening is manufactured by pressing. A hollow golf club head manufactured by sealing a main body with a sole lid, wherein the golf club head main body has a molybdenum equivalent of 0 to 10.
Precision casting with a titanium alloy containing
Cooling time in the as-cast state until the temperature reaches 20 ° C.
A golf club head manufactured by controlling for 60 minutes.