US20060025235A1

US20060025235A1 - Hollow golf club head

Info

Publication number: US20060025235A1
Application number: US10/899,157
Authority: US
Inventors: Norihiko Nakahara; Yoh Nishizawa; Tomoaki Mori
Original assignee: Yokohama Rubber Co Ltd
Current assignee: Yokohama Rubber Co Ltd
Priority date: 2004-07-27
Filing date: 2004-07-27
Publication date: 2006-02-02

Abstract

Provided is a hollow golf club head capable of improving repulsion and degree of design freedom compared to the case where a golf club head is formed using only a single metallic material, by combining different kinds of materials as component materials of a face section. The face section of the hollow golf club head is made of a composite material in which metal and fiber-reinforced plastic are combined. For example, in the hollow golf club head comprising a plate member disposed on the face section, the plate member is partially made of fiber-reinforced plastic in a plane direction and the remainder of said plate member is made of metal.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a golf club head having a hollow structure and, more specifically, to a hollow golf club head in which repulsion and degree of design freedom are improved compared to the case where the golf club head is formed using only a single metallic material, by combining different kinds of materials as component materials of the face section.
2. Description of the Related Art
In a metallic hollow golf club head, in general, a large weight proportion is placed in the sole section in order to keep the center of gravity low. However, recently, it has been required to increase the head volume as much as possible within a limited mass of the head. Thus, the margin of the weight for keeping the center of gravity low becomes small and the varsity of the possible form features becomes limited. Therefore, the center of gravity of the head cannot be maintained sufficiently low or deep. Further, in the conventional hollow golf club head, the repulsion of the face surface cannot be utilized to maximum.
Japanese Patent No. 2764883, Japanese Patent Laid-Open No. 2000-229135, and Japanese Patent No. 2773009 disclose a golf club head formed by using a composite material in which different kinds of materials are combined. However, in the golf club head formed by using the material in which properties of the different kinds of materials are combined, the varsity of the possible form features and the repulsion are still insufficient.
Also, Japanese Patent No. 3007840 discloses a hollow golf club head in which several plate members are laminated to be disposed on the face section and only peripheral portions of the plate members are bonded to a head body. In the hollow golf club head, plate members can mutually slide to allow displacement. Thus, by reducing the thickness of each plate member, it is possible to increase the deflection amount and improve repulsion while maintaining the strength based on the overall thickness of a plurality of plate members. However, in the golf club head in which pluralities of the plate members are laminated to be disposed on the face section, the weight is increased, so that the weight margin is decreased and the varsity of the possible form features becomes limited. Thus, it is difficult to keep the center of gravity low or deep. The repulsion of the head is also insufficient.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a hollow golf club head capable of improving repulsion and degree of design freedom compared to the case where the golf club head is formed using only a single metallic material, by combining different kinds of materials as component materials of the face section.
In order to achieve the foregoing object, the hollow golf club head of the present invention in which a plate member is disposed on the face section is characterized in that the plate member is partially made of fiber-reinforced plastic in a plane direction and the remainder of the plate member is made of metal. More specifically, at least either the peripheral portion or the center portion is made of fiber-reinforced plastic over the entire thickness and the remainder of the plate member is made of metal.
Further, in order to achieve the foregoing object, the hollow golf club head of the present invention in which a plate member is disposed on the face section is characterized in that the plate member is made of metal and a reinforcing member made of fiber-reinforced plastic is laminated to the back face of the plate member.
As described, metal and fiber-reinforced plastic are combined as the component material of the face section so that weight of the face section can be reduced and a larger weight margin can be obtained. Accordingly, compared to the case where the face section is formed using only a single kind of metal, the degree of design freedom can be improved. As a result, the center of gravity of the head can be lowered and deepened. Also, by specifying the area to which the metal and the fiber-reinforced plastic are applied as described above, it enables to improve the repulsion of the head.
Further, in order to achieve the foregoing object, the hollow golf club head of the present invention in which several laminated plate members are disposed on the face section and only the peripheral portions of the plate members are bonded to a head body is characterized in that at least one of the plate members is made of metal and the other members are made of fiber-reinforced plastic.
Furthermore, in order to achieve the foregoing object, the hollow golf club head of the present invention in which several laminated plate members are disposed on the face section and only the peripheral portions of the plate members are bonded to the head body is characterized in that at least one of the plate members is partially made of fiber-reinforced plastic in a plane direction and the remainder of the plate members is made of metal. More specifically, at least either the peripheral portions or the center portions of the plate members are made of fiber-reinforced plastic over the entire thickness and the remainder of said plate members is made of metal.
Further, in order to achieve the foregoing object, the hollow golf club head of the present invention in which a plurality of laminated plate members are disposed on the face section and only the peripheral portions of the plate members are bonded to a head body is characterized in that the plurality of the plate members are made of metal and a reinforcing member made of fiber-reinforced plastic is laminated to an opposing face of the plate members.
Furthermore, in order to achieve the foregoing object, the hollow golf club head of the present invention in which a plurality of laminated plate members are disposed on the face section and only the peripheral portions of the plate members are bonded to a head body is characterized in that the plurality of the plate members are made of metal and a spacer made of fiber-reinforced plastic is interposed between the peripheral portions of the plate members.
In the hollow golf club head in which a plurality of laminated plate members are disposed on the face section, metal and fiber-reinforced plastic are combined as the component material of the face section, so that weight of the face section can be reduced and a larger weight margin can be obtained. Accordingly, compared to the case where the face section is formed using only a single kind of metal, the degree of design freedom can be improved. As a result, the center of gravity of the head can be lowered and deepened. Also, the plurality of the plate members can be slid to be displaced from each other. Thus, by reducing the thickness of each plate member, it is possible to increase the deflection amount of the face section and improve the repulsion while maintaining the strength based on the overall thickness of a plurality of plate members.
As for the metal to be used, two or more kinds of metals can be combined. As for the fiber-reinforced plastic to be used, two or more kinds of fiber-reinforced plastics can be combined. As the fiber-reinforced plastic, the one with the fiber having an elastic modulus of less than 27 ton/mm²or the one with the fiber having an elastic modulus of 27 ton/mm²or more can be appropriately selected according to the position of the face section so as to increase the rigidity in the peripheral portion of the face section than that of the center portion of the face section. Thereby, the face section can be easily deflected, so that the repulsion can be further improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) to 1(c) show a golf club head according to the first embodiment of the present invention, in which FIG. 1(a) is a plan view, FIG. 1(b) is a front view, and FIG. 1(c) is a cross section taken along the line I-I;
FIGS. 2(a) to 2(c) show a golf club head according to a second embodiment of the present invention, in which FIG. 2(a) is a plan view, FIG. 2(b) is a front view, and FIG. 2(c) is a cross section taken along the line II-II;
FIGS. 3(a) to 3(c) show a golf club head according to a third embodiment of the present invention, in which FIG. 3(a) is a plan view, FIG. 3(b) is a front view, and FIG. 3(c) is a cross section taken along the line III-III;
FIGS. 4(a) to 4(c) show a golf club head according to a fourth embodiment of the present invention, in which FIG. 4(a) is a plan view, FIG. 4(b) is a front view, and FIG. 4(c) is a cross section taken along the line IV-IV;
FIGS. 5(a) to 5(c) show a golf club head according to a fifth embodiment of the present invention, in which FIG. 5(a) is a plan view, FIG. 5(b) is a front view, and FIG. 5(c) is a cross section taken along the line V-V;
FIGS. 6(a) to 6(c) show a golf club head according to a sixth embodiment of the present invention, in which FIG. 6(a) is a plan view, FIG. 6(b) is a front view, and FIG. 6(c) is a cross section taken along the line VI-VI;
FIGS. 7(a) to 7(c) show a golf club head according to a seventh embodiment of the present invention, in which FIG. 7(a) is a plan view, FIG. 7(b) is a front view, and FIG. 7(c) is a cross section taken along the line VII-VII;
FIGS. 8(a) to 8(c) show a golf club head according to en eighth embodiment of the present invention, in which FIG. 8(a) is a plan view, FIG. 8(b) is a front view, and FIG. 8(c) is a cross section taken along the line VIII-VIII;
FIGS. 9(a) to 9(c) show a golf club head according to a ninth embodiment of the present invention, in which FIG. 9(a) is a plan view, FIG. 9(b) is a front view, and FIG. 9(c) is a cross section taken along the line IX-IX;
FIGS. 10(a) to 10(c) show a golf club head according to a tenth embodiment of the present invention, in which FIG. 10(a) is a plan view, FIG. 10(b) is a front view, and FIG. 10(c) is a cross section taken along the line X-X; and
FIGS. 11(a) to 11(c) show a golf club head according to an eleventh embodiment of the present invention, in which FIG. 11(a) is a plan view, FIG. 11(b) is a front view, and FIG. 11(c) is a cross section taken along the line XI-XI;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the appended drawings, the configuration of the present invention will be described in detail below.
FIGS. 1(a) to 1(c) show the golf club head according to the first embodiment of the present invention. As shown in FIGS. 1(a) to 1(c), the golf club head according to the present embodiment has a hollow structure, and a plate member 2 is disposed on the face section of a head body 1 thereof. A peripheral portion 2 a of the plate member 2 is made of fiber-reinforced plastic, and the remainder is made of metal as the other section of the head body 1 than the face section. In this case, the fiber-reinforced plastic with the elastic modulus of fiber of less than 27 ton/mm²is used for the peripheral portion 2 a of the plate member 2. As a result, the center and the peripheral portion of the face section have high rigidity and low rigidity respectively.
FIGS. 2(a) to 2(c) show the golf club head according to the second embodiment of the present invention. As shown in FIGS. 2(a) to 2(c), the golf clu b head according to the present embodiment has a hollow structure, and a plate member 2 is disposed on the face section of a head body 1 thereof. A center portion 2 b of the plate member 2 is made of fiber-reinforced plastic, and the remainder is made of metal as the other section of the head body 1 than the face section. In this case, the fiber-reinforced plastic with the elastic modulus of fiber of 27 ton/mm²or more is used for the center portion 2 b of the plate member 2. As a result, the center and the peripheral portion of the face section have high rigidity and low rigidity respectively.
FIGS. 3(a) to 3(c) show the golf club head according to the third embodiment of the present invention. As shown in FIGS. 3(a) to 3(c), the golf club head according to the present embodiment has a hollow structure, and a plate member 2 is disposed on the face section of a head body 1 thereof A peripheral portion 2 a and a center portion 2 b of the plate member 2 are made of fiber-reinforced plastic, and the remainder is made of metal as the other section of the head body 1 than the face section. In this case, the fiber-reinforced plastic with the elastic modulus of fiber of less than 27 ton/mm²is used for the peripheral portion 2 a of the plate member 2, while the fiber-reinforced plastic with the elastic modulus of fiber of 27 ton/mm²or more is used for the center portion 2 b of the plate member 2. As a result, the center and the peripheral portion of the face section have high rigidity and low rigidity respectively.
FIGS. 4(a) to 4(c) show the golf club head according to the fourth embodiment of the present invention. As shown in FIGS. 4(a) to 4(c), the golf club head according to the present embodiment has a hollow structure, and a plate member 2 is disposed on the face section of a head body 1 thereof. The plate member 2 is made of metal as the other section of the head body 1 than the face section, and a reinforcing member 3, which is made of fiber-reinforced plastic, is laminated to the back face thereof. Furthermore, the thickness of the plate member 2 is reduced compared to the conventional case with the addition of the reinforcing member 3. In this case, the thickness of the reinforcing member 3 is increased gradually from the peripheral portion side of the face section towards the center thereof. As a result, the center and the peripheral portion of the face section have high rigidity and low rigidity respectively.
In the first to fourth embodiments described above, the face section of the head body 1 is made of composite material of metal and fiber-reinforced plastic. Thus, the mass of the face section can be lightened and a larger weight margin can be obtained. Accordingly, compared to the case where the face section is formed using only a single kind of metal, the degree of design freedom can be improved. As a result, the center of gravity of the head can be lowered and deepened. Furthermore, by appropriately selecting the properties of the fiber-reinforced plastic, the center and the peripheral portion of the face section are provided with high rigidity and low rigidity respectively. Thereby, the face section can be easily deflected and the repulsion can be further improved.
The fiber-reinforced plastic mentioned above includes those obtained by impregnating matrix resin such as epoxy resin, unsaturated polyester resin, vinyl ester resin or the like with reinforcing fiber such as carbon fiber, glass fiber, aramid fiber or the like. The fiber-reinforced plastic that uses carbon fiber as the reinforcing fiber is especially preferable. Further, titanium alloy, aluminum alloy, stainless steel or the like can be used alone or in combination for the metal mentioned above.
FIGS. 5(a) to 5(c) show the golf club head according to the fifth embodiment of the present invention. As shown in FIGS. 5(a) to 5(c), the golf club head according to the present embodiment has a hollow structure, and several plate members 2, 2 are laminated and disposed on the face section of a head body 1 thereof. Only the peripheral portions of the plate members 2, 2 are unified with the head body 1. The outer plate member 2 is made of metal as the other section of the head body 1 than the face section, and the inner plate member 2 is made of fiber-reinforced plastic. In this case, the thickness of the plate member 2, which is made of fiber-reinforced plastic, is increased gradually from the peripheral portion side of the face section towards the center thereof. As a result, the center and the peripheral portion of the face section have high rigidity and low rigidity respectively.
FIGS. 6(a) to 6(c) show the golf club head according to the sixth embodiment of the present invention. As shown in FIGS. 6(a) to 6(c), the golf club head according to the present embodiment has a hollow structure, and several plate members 2, 2 are laminated and disposed on the face section of a head body 1 thereof. Only the peripheral portions of the plate members 2, 2 are unified with the head body 1. The peripheral portion 2 a of each plate member 2 is made of the fiber-reinforced plastic, and the remainder is made of metal as the other section of the head body 1 than the face section. In this case, the fiber-reinforced plastic with the elastic modulus of fiber of less than 27 ton/mm²is used for the peripheral portion 2 a of the plate member 2. As a result, the center and the peripheral portion of the face section have high rigidity and low rigidity respectively.
FIGS. 7(a) to 7(c) show the golf club head according to the seventh embodiment of the present invention. As shown in FIGS. 7(a) to 7(c), the golf club head according to the present embodiment has a hollow structure, and several plate members 2, 2 are laminated and disposed on the face section of a head body 1 thereof. Only the peripheral portions of the plate members 2, 2 are unified with the head body 1. The center portion 2 b of each plate member 2 is made of the fiber-reinforced plastic, and the remainder is made of metal as the other section of the head body 1 than the face section. In this case, the fiber-reinforced plastic with the elastic modulus of fiber of 27 ton/mm²or more is used for the center portion 2 b of the plate member 2. As a result, the center and the peripheral portion of the face section have high rigidity and low rigidity respectively.
FIGS. 8(a) to 8(c) show the golf club head according to the eighth embodiment of the present invention. As shown in FIGS. 8(a) to 8(c), the golf club head according to the present embodiment has a hollow structure, and several plate members 2, 2 are laminated and disposed on the face section of a head body 1 thereof. Only the peripheral portions of the plate members 2, 2 are unified with the head body 1. A peripheral portion 2 a and a center portion 2 b of the plate member 2 are made of fiber-reinforced plastic, and the remainder is made of metal as the other section of the head body 1 than the face section. In this case, the fiber-reinforced plastic with the elastic modulus of fiber of less than 27 ton/mm²is used for the peripheral portion 2 a of the plate member 2, and the fiber-reinforced plastic with the elastic modulus of fiber of 27 ton/mm²or more is used for the center portion 2 b of the plate member 2. As a result, the center and the peripheral portion of the face section have high rigidity and low rigidity respectively.
FIGS. 9(a) to 9(c) show the golf club head according to the ninth embodiment of the present invention. As shown in FIGS. 9(a) to 9(c), the golf club head according to the present embodiment has a hollow structure, and several plate members 2, 2 are laminated and disposed on the face section of a head body 1 thereof. Only the peripheral portions of the plate members 2, 2 are unified with the head body 1. The plate members 2, 2 are made of metal as the other section of the head body 1 than the face section, and a reinforcing member 3, which is made of fiber-reinforced plastic, is laminated to the opposing back thereof. In this case, the thickness of the reinforcing member 3 is increased gradually from the peripheral portion side of the face section towards the center. As a result, the center and the peripheral portion of the face section have high rigidity and low rigidity respectively. Furthermore, the thickness of the plate member 2 is reduced compared to the conventional case with the addition of the reinforcing member 3.
FIGS. 10(a) to 10(c) show the golf club head according to the tenth embodiment of the present invention. As shown in FIGS. 10(a) to 10(c), the golf club head according to the present embodiment has a hollow structure, and several plate members 2, 2 are laminated and disposed on the face section of a head body 1 thereof. Only the peripheral portions of the plate members 2, 2 are unified with the head body 1. The plate members 2, 2 are made of metal as the other section of the head body 1 than the face portion, and a spacer 4, which is made of fiber-reinforced plastic, is inserted between the peripheral portions of the plate members. In other words, the metal spacer that is conventionally inserted between the peripheral portions of several plate members is replaced with the fiber-reinforced plastic spacer in the present embodiment.
FIGS. 11(a) to 11(c) show the golf club head according to the eleventh embodiment of the present invention. As shown in FIGS. 11(a) to 11(c), the golf club head according to the present embodiment has a hollow structure, and several plate members 2, 2 are laminated and disposed on the face section of a head body 1 thereof. Only the peripheral portions of the plate members 2, 2 are unified with the head body 1. The center portion 2 b of each plate member 2 is made of fiber-reinforced plastic, and the remainder is made of metal as the other section of the head body 1 than the face section. In this case, the fiber-reinforced plastic with the elastic modulus of fiber of 27 ton/mm²or more is used for the center portion 2 b of the plate member 2. As a result, the center and the peripheral portion of the face section have high rigidity and low rigidity respectively. Furthermore, a spacer 4, which is made of fiber-reinforced plastic, is inserted between the peripheral portions of the plate members 2, 2.
In the fifth to eleventh embodiments described above, the face section of the head body 1 is made of composite material of metal and fiber-reinforced plastic. Thus, the mass of the face section can be lightened and a larger weight margin can be obtained. Accordingly, compared to the case where the face section is formed using only a single kind of metal, the degree of design freedom can be improved. As a result, the center of gravity of the head can be lowered and deepened. Furthermore, by appropriately selecting the properties of the fiber-reinforced plastic, the center and the peripheral portion of the face section are provided with high rigidity and low rigidity respectively. Thereby, the face section can be easily deflected and the repulsion can be further improved.
Furthermore, in the fifth to eleventh embodiments described above, a plurality of the plate members 2, 2 can be slid and displaced from each other by collision of the face section of the head body 1 and a ball, causing the deflection of these plate members 2, 2. In such a case, the break strength of the face section is proportional to the overall thickness (including the reinforcing member 3) of a plurality of the plate members 2, 2, realizing the setup of a sufficient strength based on the overall thickness thereof. Meanwhile, the deflection amount of the face section increases as each of the plate members 2, 2 becomes thinner. Thus, when the face section comprises the lamination of several plate members 2, 2 as described above, the repulsion can be improved while maintaining the sufficient strength. Therefore, it is possible to achieve a notable improvement in the repulsion due to multiplier effect together with the effect of improving the repulsion by using the composite material.
The fiber-reinforced plastic mentioned above includes those obtained by impregnating matrix resin such as epoxy resin, unsaturated polyester resin, vinyl ester resin or the like with reinforcing fiber such as carbon fiber, glass fiber, aramid fiber or the like. The fiber-reinforced plastic that uses carbon fiber as the reinforcing fiber is especially preferable. Further, titanium alloy, aluminum alloy, stainless steel or the like can be used alone or in combination for the metal mentioned above.
The preferred embodiments of the present invention are described above in detail; however, it should be understood that various modifications, replacements, and displacements may be made therein, as long as such modifications, replacements, and displacements fall within the true spirit and the scope of the present invention covered by the appended claims.

EXAMPLES

First, an experiment regarding the first to fourth embodiments was carried out. The hollow golf club heads of comparative examples 1, 2 (conventional ones) in which the face sections were made of a single metallic material and that of examples 1 to 4 in which the face sections were made of a composite material of metal and fiber-reinforced plastic were fabricated, respectively. In table 1, “FRP” means the fiber-reinforced plastic, “below 27t” means that the fiber elasticity modulus is less than 27 ton/mm², and “above 27t” means that the fiber elasticity modulus is 27 ton/mm²or more.

The restitution coefficient and the degree of design freedom of the golf club heads were evaluated. The results are shown in table 1. The results of the evaluation are shown with the comparative example 1 being the index as 100. A larger index value of the restitution coefficient means the increased initial ball speed and the increased carry. The degree of design freedom is the weight margin when the overall mass of the head is constant and a larger index value of the varsity means a larger weight margin.

	TABLE 1


		Material of
	Material of plate member of face section	reinforcing

	Center	Peripheral	Remainder	member of	Thickness of face	Repulsion	Degree of
Figure	portion	portion	portion	face section	section	coefficient	design freedom

Comparative	—	Titanium	Titanium	Titanium	—	Uniform	100	100
example 1		alloy	alloy	alloy
Comparative	—	Titanium	Titanium	Titanium	—	Center -thick	105	106
example 2		alloy	alloy	alloy		Peripheral -thin
Example 1		FRP	Titanium	Titanium	—	Uniform	107	110
		(above 27t)	alloy	alloy
Example 2		Titanium	Titanium	Titanium	FRP	Center-thick	109	115
		alloy	alloy	alloy	(above 27t)	Peripheral-thin
Example 3		FRP	FRP	Titanium	—	Uniform	111	119
		(above 27t)	(below 27t)	alloy
Example 4		FRP	FRP	Titanium	—	Center-thick	115	122
		(above 27t)	(below 27t)	alloy		Peripheral-thin

As can be seen from table 1, all of the golf club heads of examples 1 to 4 exhibited a larger degree of design freedom and the restitution coefficient compared to comparative examples 1, 2.
Next, an experiment regarding the fifth to eleventh embodiments was carried out. The hollow golf club head of comparative examples 11 (conventional one) in which the face section was made of a single metallic material and that of examples 11 to 17 in which the face sections were made of a composite material of metal and fiber-reinforced plastic were fabricated, respectively. In table 2, “SUS alloy” means stainless steel, “FRP” means the fiber-reinforced plastic, “below 27t” means that the fiber elasticity modulus is less than 27 ton/mm², and “above 27t” means that the fiber elasticity modulus is 27 ton/mm²or more.

The restitution coefficient and the degree of design freedom of the golf club heads were evaluated. The results are shown in table 2. The results of the evaluation are shown with the comparative example 11 being the index as 100. A larger index value of the restitution coefficient means the increased initial ball speed and the increased carry. The degree of design freedom is the weight margin when the overall mass of the head is constant and a larger index value of the varsity means a larger weight margin.

TABLE 2


			Materi-		Degree
Material of outer plate member of face	Material of inner plate member of face	Material of	al of	Repul-	of
section	section	reinforcing	spacer	sion	design

Center

Peripheral

Remainder

Center

Peripheral

Remainder

member of

of face

coeffi-

free-

Figure

portion

face section

section

cient

dom

Comparative	—	Titanium	Titanium	Titanium	Titanium	Titanium	Titanium	—	Titanium	100	100
example 11		alloy	alloy	alloy	alloy	alloy	alloy		alloy
Example 11		Titanium	Titanium	Titanium	FRP	FRP	FRP	—	—	103	118
		alloy	alloy	alloy	(above27t)	(below27t)	(below27)
Example 12		Titanium	Titanium	Titanium	Titanium	Titanium	Titanium	FRP	—	104	102
		alloy	alloy	alloy	alloy	alloy	alloy	(above27t)
Example 13		FRP	Titanium	Titanium	FRP	Titanium	Titanium	—	—	106	105
		(above27t)	alloy	alloy	(above27t)	alloy	alloy
Example 14		Titanium	FRP	Titanium	Titanium	FRP	Titanium	—	—	105	103
		alloy	(below27t)	alloy	alloy	(below27t)	alloy
Example 15		FRP	FRP	Titanium	FRP	FRP	Titanium	—	—	108	106
		(above27t)	(below27t)	alloy	(above27t)	(below27t)	alloy
Example 16		Titanium	Titanium	Titanium	Titanium	Titanium	Titanium	—	FRP (be-	109	103
		alloy	alloy	alloy	alloy	alloy	alloy		low27t)
Example 17		FRP	Titanium	Titanium	FRP	SUS alloy	SUS alloy	—	FRP (be-	110	106
		(above27t)	alloy	alloy	(above27t)				low27t)

As can be seen from table 2, all of the golf club head of examples 11 to 17 exhibited a larger degree of design freedom and the restitution coefficient compared to the comparative example 11.

Claims

1. A hollow golf club head in which a plate member is disposed on a face section, wherein

said plate member is partially made of fiber-reinforced plastic in a plane direction and the remainder of said plate member is made of metal.

2. The hollow golf club head as claimed in claim 1, wherein a peripheral portion of said plate member is made of fiber-reinforced plastic and the remainder of said plate member is made of metal.

3. The hollow golf club head as claimed in claim 1, wherein a center portion of said plate member is made of fiber-reinforced plastic and the remainder of said plate member is made of metal.

4. The hollow golf club head as claimed in claim 1, wherein a peripheral portion and a center portion of said plate member are made of fiber-reinforced plastic and the remainder of said plate member is made of metal.

5. A hollow golf club head in which a plate member is disposed on a face section, wherein

said plate member is made of metal and a reinforcing member made of fiber-reinforced plastic is laminated to the back face of said plate member.

6. The hollow golf club head as claimed in any one of claims 1 to 5, wherein, as said fiber-reinforced plastic, two or more kinds of fiber-reinforced plastics are combined to be used.

7. The hollow golf club head as claimed in any one of claims 1 to 5, wherein an elastic modulus of fiber in said fiber-reinforced plastic is less than 27 ton/mm².

8. The hollow golf club head as claimed in any one of claims 1 to 5, wherein an elastic modulus of fiber in said fiber-reinforced plastic is 27 ton/mm²or more.

9. A hollow golf club head in which a plurality of laminated plate members are disposed on a face section and only the peripheral portions of said plate members are bonded to a head body, wherein

at least one of said plate members is made of metal and the other members are made of fiber-reinforced plastic.

10. A hollow golf club head in which a plurality of laminated plate members are disposed on a face section and only the peripheral portions of said plate members are bonded to a head body, wherein

at least one of said plate members is partially made of fiber-reinforced plastic in a plane direction and the remainder of said plate members is made of metal.

11. The hollow golf club head as claimed in claim 10, wherein the peripheral portions of said plate members are made of fiber-reinforced plastic and the remainder of said plate members is made of metal.

12. The hollow golf club head as claimed in claim 10, wherein a center portions of said plate members are made of fiber-reinforced plastic and the remainder of said plate members is made of metal.

13. The hollow golf club head as claimed in claim 10, wherein the peripheral portions and center portions of said plate members are made of fiber-reinforced plastic and the remainder of said plate members is made of metal.

14. A hollow golf club head in which a plurality of laminated plate members are disposed on a face section and only the peripheral portions of said plate members are bonded to a head body, wherein

said plurality of plate members are made of metal and a reinforcing member made of fiber-reinforced plastic is laminated to an opposing face of said plate members.

15. A hollow golf club head in which a plurality of laminated plate members are disposed on a face section and only the peripheral portions of said plate members are bonded to a head body, wherein

said plurality of plate members are made of metal and a spacer made of fiber-reinforced plastic is interposed between the peripheral portions of said plate members.

16. The hollow golf club head as claimed in any one of claims 9 to 15, wherein, as said metal, two or more kinds of metals are combined to be used.

17. The hollow golf club head as claimed in any one of claims 9 to 15, wherein, as said fiber-reinforced plastic, two or more kinds of fiber-reinforced plastics are combined to be used.

18. The hollow golf club head as claimed in any one of claims 9 to 15, wherein an elastic modulus of fiber in said fiber-reinforced plastic is less than 27 ton/mm².

19. The hollow golf club head as claimed in any one of claims 9 to 15, wherein an elastic modulus of fiber in said fiber-reinforced plastic is 27 ton/mm²or more.