GOLF CLUB HEAD

Abstract

A golf club head includes: a back portion; and a front striking portion connected to the back portion and having a thickness ranging from 1.0 mm to 4.2 mm. The front striking portion includes a striking front face plate that has a characteristic time ranging from 220 μ sec-257 μsec. The front striking portion is made by rolling a titanium-based alloy and the titanium-based alloy has a density ranging from 4.35 g/cm3 to 4.36 g/cm3, a tensile strength ranging from 130 ksi to 146 ksi, a yield strength ranging from 120 ksi to 132 ksi, and a Young's modulus ranging from 120 Gpa to 135 Gpa. A total volume of the back and front striking portions ranges from 300 cc to 460 cc, and a total weight of the back and front striking portions ranges from 170 grams to 220 grams.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a golf equipment, and more particularly to a golf club head.

2. Description of the Related Art

Golf sport involves a player twisting his/her waist to swing a golf club and strike a golf ball. Thus, in addition to having relatively high strength and abrasion resistance to enhance stroke stability, the golf club is required to have a suitable weight to minimize player fatigue when swinging the same.

Consequently, the golf equipment industry has been aggressive in searching, developing and designing new materials and manufacturing procedures for golf club heads. In particular, current major research and development of the golf equipment industry focus on preparation of the golf club head having various properties with alloys of different compositions. A golf club head made of 6Al-4V Ti alloy is most popular in recent years, since it has good mechanical strength as shown in Table 1 and abrasion resistance and satisfies the general requirements for strokes. Hence, the golf club head made of 6Al-4V Ti alloy is favored by golfers.

TABLE 1
Mechanical properties of 6Al—4V Ti alloy
		Tensile	Yield	Young's
Material	Density	strength	strength	modulus
6Al—4V Ti	4.43 g/cm3	152 ksi	143 ksi	105-116 Gpa
alloy

In order to avoid unrestricted enhancement in performance of the golf club head by manufacturers of the same and maintain fairness in golf competitions, the

United States Golf Association (USGA) has issued regulations governing the golf club head, wherein a maximum “characteristic time” (CT) that is a contact time between the face of the golf club head and a golf ball regulated by the USGA is lower than 257 μsec. That is to say, no matter what material the golf club head is made from, and no matter what shape the golf club head has, the CT value of the face of the golf club head should be lower than 257 μsec. The larger the CT value, the farther the golf ball flies. Therefore, almost all of the faces of the commercially available golf club heads are made to have the CT value close to 257 μsec.

The characteristics of the face of the golf club head made of 6Al-4V Ti alloy are shown in Table 2, in which the face of the golf club head has a CT value of 253 μsec and strength of 24880 hits. The weight of the golf club head is 188.5 grams.

It should be noted that, in Table 2, the value of “strength” of the face of the golf club head was tested by firing golf balls using a hitting machine at a velocity of 58 m/sec on the face, until the face breaks, and recording the total number of the golf balls fired from the hitting machine (hits). Based on current strength standard of faces of commercial golf clubs, the face of the golf club head is hit by golf balls fired from the hitting machine at a velocity of 50 m/sec, and the face is deemed to satisfy the strength standard of faces of commercial golf clubs if the face breaks after more than 3000 hits of the golf balls.

TABLE 2
Properties of the face of the golf club made of 6Al—4V Ti alloy
	Material	CT value	Weight	Strength
	6Al—4V Ti	253 μsec	188.5 g	24880 hits
	alloy

In view of the foregoing, although the face made of 6Al-4V Ti alloy can conform to the requirements for the CT value and the strength, the strength of the face is far higher than the requirement for faces of commercial golf clubs. It is well-known that the strength of the face may be reduced by decreasing the thickness thereof, thereby reducing the weight of the face at the same time. However, the CT value of the face will increase as a result of reduction of strength caused by decrease in the thickness. Since the CT value of the face made of 6Al-4V Ti alloy without decrease in thickness is very close to the maximum CT value, reduction of the strength of the face made of 6Al-4V Ti alloy by decreasing the thickness thereof will cause the CT value of the face to go beyond the maximum CT value.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a golf club head that is lightweight, has good mechanical properties, and has a CT value close to the upper limit (257 μsec) regulated by the USGA and a strength close to the lower limit (3000 hits) of the strength standard of the faces of commercial golf clubs.

Accordingly, a golf club head of the present invention comprises:

a back portion; and

a front striking portion connected to the back portion and having a thickness ranging from 1.0 mm to 4.2 mm, the front striking portion including a striking front face plate that has a characteristic time ranging from 220 μsec -257 μsec, the front striking portion being made by rolling a titanium-based alloy that has a density ranging from 4.35 g/cm³ to 4.36 g/cm³, a tensile strength ranging from 130 ksi to 146 ksi, a yield strength ranging from 120 ksi to 132 ksi, and a Young's modulus ranging from 120 Gpa to 135 Gpa;

wherein a total volume of the back and front striking portions ranges from 300 cc to 460 cc, and a total weight of the back and front striking portions ranges from 170 grams to 220 grams.

Because the striking front face plate of the front striking portion is made from the rolled titanium-based alloy with a relatively low density and a relatively high Young's modulus, it can achieve effects including lightweight, good mechanical strength and abrasion resistance, and can comply with the regulations of the USGA. Therefore, the golf club head of the present invention can have a reduced total weight such that a center of gravity thereof may be easily adjusted using a weight unit, while complying with the regulations of the USGA related to a golf club head.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:

FIG. 1 is a perspective view illustrating a first preferred embodiment of a golf club head according to the present invention;

FIG. 2 is an exploded perspective view illustrating a second preferred embodiment of a golf club head according to the present invention; and

FIG. 3 is an exploded perspective view illustrating a third preferred embodiment of a golf club head according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Before the present invention is described in greater detail with reference to the accompanying preferred embodiments, it should be noted herein that like elements are denoted by the same reference numerals throughout the disclosure.

Referring to FIG. 1, a golf club head 1 according to the first preferred embodiment of this invention comprises a back portion 11 and a front striking portion 12 connected to the back portion 11. The front striking portion 12 includes a striking front face plate 121 connected to the back portion 11 and has a thickness ranging from 1.0 mm to 4.2 mm. A total volume of the back portion 11 and the striking front face plate 121 ranges from 300 cc to 460 cc. A total weight of the back portion 11 and the striking front face plate 121 ranges from 170 grams to 220 grams.

The striking front face plate 121 is made by rolling a titanium-based alloy (811 Ti alloy) . Preferably, the 811 Ti alloy has a density ranging from 4.35 g/cm³ to 4.36 g/cm³, a tensile strength ranging from 130 ksi to 146 ksi, a yield strength ranging from 120 ksi to 132 ksi, and a Young's modulus ranging from 120 Gpa to 135 Gpa, and includes: aluminum in an amount ranging from 7.2 wt % to 7.8 wt %; molybdenum in an amount ranging from 0.6 wt % to 0.9 wt %; vanadium in an amount ranging from 0.6 wt % to 0.9 wt %; silicon in an amount not greater than 2.0 wt %; and a balance of titanium and an unavoidable impurity, based on a total weight of the 811 Ti alloy. In the first preferred embodiment, the 811 Ti alloy has mechanical properties shown in Table 3 and includes: aluminum in an amount of 7.5 wt %; molybdenum in an amount of 0.7 wt %; vanadium in an amount of 0.7 wt %; silicon in an amount of 0.15 wt %; and a balance of titanium and the unavoidable impurity, based on a total weight of the 811 Ti alloy.

TABLE 3
Mechanical properties of 811 Ti alloy
		Tensile	Yield	Young's
Material	Density	strength	strength	modulus
811 Ti alloy	4.35 g/cm3	146 ksi	132 ksi	132 Gpa

In the process of rolling, a 811 Ti alloy is subjected to one hot rolling treatment, followed by two cold rolling treatments. Thereafter, the 811 Ti alloy is cut to form the front striking portion 12.

Titanium is a material with properties of lightweight, high hardness, and high strength. Aluminum is a good deoxidizer. Aluminum in the amount of 7.5 wt % in combination with a large amount of titanium in the alloy reduces specific gravity of the alloy, and thus, the golf club head made of the alloy according to the present invention has a relatively lightweight per unit volume. Moreover, aluminum inhibits grain overgrowth and promotes dispersion of oxides and nitrides in the alloy. Thus, the grains of the alloy are maintained with a relatively small size, and the ductility, workability and toughness of the alloy are improved.

However, since the alloy has aluminum in the amount of up to 7.5 wt %, the alloy has a relatively low flowability unsuitable to be made by a casting method. Besides, since the addition of aluminum can enhance the ductility, workability and toughness of the alloy, the striking front face plate 121 should be made by rolling to improve precision and production rate of the same.

Molybdenum increases hot strength, creep strength and hot hardness of the alloy, and thus, the striking front face plate 121 as made can be made to have increased abrasion resistance and strength. If the striking front face plate 121 as made is further subjected to a plating treatment, the corrosion resistance and oxidation resistance may be further improved.

Vanadium is effective to avoid formation of coarse grains and to make the grain size of the alloy finer, and thus, the mechanical strength and abrasion resistance of the striking front face plate 121 of the golf club head 1 may be improved.

Silicon makes grains of the alloy to be uniformly and finely formed to enhance the mechanical strength of the alloy, while not adverse to elongation of the alloy. In order to demonstrate the effects of the golf club head 1 of the present invention, the applicants conducted experiments with respect to the front striking portions 12 respectively made of the 811 Ti alloy of this invention and the conventional 6Al-4V Ti alloy, and the results thereof are shown in Table 4. It should be noted that, in Table 4, Examples 1 to 3 indicate the striking front face plates 121 of the front striking portions 12 being made from the 811 Ti alloy of this invention, and Comparative Example indicates the striking front face plate 121 of the front striking portion 12 being made from the conventional 6Al-4V Ti alloy. The strength for each of the striking front face plates 121 in Table 4 was tested by firing golf balls in a hitting machine at a velocity of 64 m/sec on right, middle and left portions of each striking front face plate 121 for 1000 hits, respectively, followed by firing golf balls on the middle portion of each striking front face plate 121 until the striking front faceplate 121 breaks, and the total number of the golf balls (hits) needed to break each striking front face plate 121 was recorded.

TABLE 4
Comparison between front striking portions made of 811 Ti alloy
of this invention and the conventional 6Al—4V Ti alloy
		Thickness	Weight	CT value	Strength
	Example	(mm)	(g)	(μsec)	(hit)
	Comparative	4.0/2.2	188.5	253	3651
	Example
	Example 1	4.0/2.2	187	233	5100
	Example 2	4.1/2.3	188.5	232	7248
	Example 3	3.7/1.9	182.4	252	3399
	* The column of thickness shows the maximum and the minimum values of the thickness.

As shown in Table 4, when the thicknesses of the front striking portions 12 of this invention and Comparative example are the same (see Example 1 and Comparative Example) the front striking portion 12 of Example 1 is lighter than that of Comparative Example by 1.5 grams, since the 811 Ti alloy has a specific gravity lower than that of the 6Al-4V Ti alloy. Besides, since the Young's modulus of the 811 Ti alloy is larger than that of the 6Al-4V Ti alloy (i.e., the 811 Ti alloy has a higher resilience potential than that of the 6Al-4V Ti alloy) the CT value of the striking front face plate 121 of Example 1 is lower than that of Comparative Example by 20 μsec. Furthermore, the strength of the striking front face plate 121 of Example 1 is higher than that of Comparative Example by 1449 hits.

When the weight of the front striking portions 12 of this invention and Comparative Example are the same (see Example 2 and Comparative Example) the thickness of the front striking portion 12 of Example 2 is thicker than that of Comparative Example by 0.1 mm, since the 811 Ti alloy has the specific gravity lower than that of the 6Al-4V Ti alloy. Because the 811 Ti alloy has relatively larger thickness and Young's modulus than those of the 6Al-4V Ti alloy, the CT value of the striking front face plate 121 of Example 2 is lower than that of Comparative Example by 21 μsec at the same weight . Besides, the strength of the striking front face plate 121 of Example 2 is higher than that of Comparative Example by 3597 hits.

When the CT values of the striking front face plate 121 of this invention and Comparative Example are similar (see Example 3 and Comparative Example) , the thickness of the front striking portion 12 of Example 3 is thinner than that of Comparative Example by 0.3 mm. With the reduction of the thickness, the weight of the front striking portion 12 of Example 3 is lighter than that of Comparative Example by 6.1 grams. Although the strength of the striking front face plate 121 of Example 3 is lower than that of Comparative Example by 252 hits, the front striking portion 12 of Example 3 is lighter than that of Comparative Example and the striking front face plate 121 has the CT value that is close to that of the Comparative Example and that complies with the commercial requirement for a front striking portion of a golf club head.

Therefore, when the front striking portions 12 of this invention and Comparative Example have similar CT values, the front striking portion 12 of this invention can be lighter and thinner, and can comply with the strength requirement for faces of the commercial golf clubs. Accordingly, by virtue of the golf club head 1 using the striking front face plate 121 of the front striking portion 12 of this invention, the weight of the golf club head 1 can be reduced, and the reduced weight can enhance flexibility of adjustment of a center of gravity of the golf club head 1 and disposition of a weight unit in the golf club head 1.

FIG. 2 illustrates the second preferred embodiment of a golf club head 1 of this invention. The second preferred embodiment differs from the first preferred embodiment only in that the front striking portion 12 further includes a peripheral flange 123 fixed to the back portion 11. The striking front face plate 121 has top and bottom ends and two opposite sides interconnecting the top and bottom ends. The peripheral flange 123 extends rearwardly from the top and bottom ends and the two opposite sides of the striking front face plate 121. Since the striking front face plate 121 of the front striking portion 12 of this preferred embodiment is also made from the 811 Ti alloy, the golf club head 1 of the second preferred embodiment of this invention can achieve the effect of the first preferred embodiment and may serve as an alternative for users.

FIG. 3 illustrates the third preferred embodiment of a golf club head 1 of this invention. The third preferred embodiment differs from the first preferred embodiment only in that the front striking portion 12 further includes a bottom plate 124 that extends rearwardly from a bottom end of the striking front face plate 121. The striking front face plate 121 and the bottom plate 124 are fixed to the back portion 11. The golf club head 1 of the third preferred embodiment of this invention may serve as another alternative for users.

In the second and third embodiments, the front striking portion 12 is made in a manner similar to that of the first preferred embodiment, but the 811 Ti alloy further undergoes forging after rolling of the same.

In summary, since the front striking portion 12 of the golf club head 1 of this invention is made by rolling the titanium-based alloy and the titanium-based alloy has a density ranging from 4.35 g/cm³ to 4.36 g/cm³, a tensile strength ranging from 130 ksi to 146 ksi, a yield strength ranging from 120 ksi to 132 ksi, and a Young's modulus ranging from 120 Gpa to 135 Gpa, it can achieve effects including lightweight, good mechanical strength and abrasion resistance, and can comply with the regulations of the USGA. Furthermore, since the total volume of the back and front striking portions 11, 12 ranges from 300 cc to 460 cc, and since the total weight of the back and front striking portions 11, 12 ranges from 170 grams to 220 grams, the total weight of the golf club head 1 may be reduced, a center of gravity of the golf club head 1 may be easily adjusted, and the golf club head 1 of this invention can also comply with the regulations of the USGA related to a golf club head.

While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.

Claims

1. A golf club head comprising:

a back portion; and

a front striking portion connected to said back portion and having a thickness ranging from 1.0 mm to 4.2 mm, said front striking portion including a striking front face plate that has a characteristic time ranging from 220 μsec -257 μsec, said front striking portion being made by rolling a titanium-based alloy that has a density ranging from 4.35 g/cm3 to 4.36 g/cm3, a tensile strength ranging from 130 ksi to 146 ksi, a yield strength ranging from 120 ksi to 132 ksi, and a Young's modulus ranging from 120 Gpa to 135 Gpa;

wherein a total volume of said back and front striking portions ranges from 300 cc to 460 cc, and a total weight of said back and front striking portions ranges from 170 grams to 220 grams.

2. The golf club head of claim 1, wherein said titanium-based alloy includes: aluminum in an amount ranging from 7.2 wt % to 7.8 wt %; molybdenum in an amount ranging from 0.6 wt % to 0.9 wt %; vanadium in an amount ranging from 0.6 wt % to 0.9 wt %; silicon in an amount not greater than 2.0 wt %; and a balance of titanium and an unavoidable impurity, based on a total weight of said titanium-based alloy.

3. The golf club head of claim 1, wherein said titanium-based alloy includes: aluminum in an amount of 7.5 wt %; molybdenum in an amount of 0.7 wt %; vanadium in an amount of 0.7 wt %; silicon in an amount of 0.15 wt %; and a balance of titanium and an unavoidable impurity, based on a total weight of said titanium-based alloy.

4. The golf club head of claim 1, wherein said front striking portion further includes a peripheral flange fixed to said back portion, said striking front face plate having top and bottom ends and two opposite sides interconnecting said top and bottom ends, said peripheral flange extending rearwardly from said top and bottom ends and said two opposite sides of said striking front face plate.

5. The golf club head of claim 1, wherein said front striking portion further includes a bottom plate that extends rearwardly from a bottom end of said striking front face plate, said striking front face plate and said bottom plate being fixed to said back portion.