U.S. patent application number 17/348992 was filed with the patent office on 2022-01-20 for golf club head.
The applicant listed for this patent is BRIDGESTONE SPORTS CO., LTD.. Invention is credited to Takaharu TAKECHI.
Application Number | 20220016497 17/348992 |
Document ID | / |
Family ID | 1000005668170 |
Filed Date | 2022-01-20 |
United States Patent
Application |
20220016497 |
Kind Code |
A1 |
TAKECHI; Takaharu |
January 20, 2022 |
GOLF CLUB HEAD
Abstract
A golf club head having a hollow structure and including a face,
a body, and a weight portion is provided. The body includes a
crown, a sole, and a hosel chamber. The crown, the sole, and the
hosel chamber include laminated layers of a fiber-reinforced resin.
The weight portion is formed of a material having a specific
gravity greater than specific gravities of the crown and of the
sole. The head volume is greater than or equal to 450 cc and less
than or equal to 470 cc. The head weight is less than or equal to
200 g. The average thickness of each of the crown and the sole is
greater than or equal to 0.7 mm. The weight of the weight portion
is greater than or equal to 20 g, and the weight portion is
attached to one or both of the crown and the sole.
Inventors: |
TAKECHI; Takaharu; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BRIDGESTONE SPORTS CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
1000005668170 |
Appl. No.: |
17/348992 |
Filed: |
June 16, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A63B 53/0433 20200801;
A63B 53/0412 20200801; A63B 53/0466 20130101 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 15, 2020 |
JP |
2020-121409 |
Jul 15, 2020 |
JP |
2020-121410 |
Claims
1. A golf club head having a hollow structure, the golf club head
comprising: a face; a body including at least a crown, a sole, and
a hosel chamber, the crown, the sole, and the hosel chamber
including laminated layers of a fiber-reinforced resin; and a
weight portion formed of a material having a specific gravity
greater than specific gravities of the crown and of the sole, and
disposed inward relative to a head shell, wherein a head volume is
greater than or equal to 450 cc and less than or equal to 470 cc,
wherein a head weight is less than or equal to 200 g, wherein an
average thickness of each of the crown and the sole is greater than
or equal to 0.7 mm, and wherein a weight of the weight portion is
greater than or equal to 20 g, and the weight portion is attached
to one or both of the crown and the sole.
2. The golf club head according to claim 1, wherein a
characteristic time (CT), corresponding to a coefficient of
restitution of the face, is less than or equal to 257 .mu.s.
3. The golf club head according to claim 1, wherein the head weight
is greater than or equal to 180 g, and the weight of the weight
portion is greater than or equal to 30 g and less than or equal to
55 g.
4. The golf club head according to claim 1, wherein the weight
portion is not exposed to inside of and outside of the body.
5. The golf club head according to claim 1, wherein the weight
portion has a first surface and a second surface, the first surface
contacting the head shell and the second surface not contacting the
head shell, at least one layer of a fiber-reinforced resin is
provided on the second surface, and the at least one layer of the
fiber-reinforced resin contacts one or both of an inner surface of
the crown and an inner surface of the sole.
6. The golf club head according to claim 1, wherein a maximum head
height is greater than or equal to 60 mm, and a maximum head width
is greater than or equal to 112 mm.
7. The golf club head according to claim 1, wherein the weight of
the weight portion is 20% or more of the head weight.
8. The golf club head according to claim 1, wherein the sole
includes a rib formed of a fiber-reinforced resin.
9. A golf club head having a hollow structure, the golf club head
comprising: a face; a body including at least a crown, a sole, and
a hosel chamber, the crown, the sole, and the hosel chamber
including laminated layers of a fiber-reinforced resin; and a
weight portion formed of a material having a specific gravity
greater than specific gravities of the crown and of the sole, and
disposed inward relative to a head shell, wherein a head volume is
greater than or equal to 450 cc and less than or equal to 470 cc,
wherein a head weight is less than or equal to 180 g, wherein an
average thickness of each of the crown and the sole is greater than
or equal to 0.7 mm, and wherein a weight of the weight portion is
greater than or equal to 10 g, and the weight portion is attached
to one or both of the crown and the sole.
10. The golf club head according to claim 9, wherein a
characteristic time (CT), corresponding to a coefficient of
restitution of the face, is less than or equal to 257 .mu.s.
11. The golf club head according to claim 9, wherein the head
weight is greater than or equal to 160 g, and the weight of the
weight portion is less than or equal to 35 g.
12. The golf club head according to claim 9, wherein the weight
portion is not exposed to inside of and outside of the body.
13. The golf club head according to claim 9, wherein the weight
portion has a first surface and a second surface, the first surface
contacting the head shell and the second surface not contacting the
head shell, at least one layer of a fiber-reinforced resin is
included at the second surface, and the at least one layer of the
fiber-reinforced resin contacts one or both of an inner surface of
the crown and an inner surface of the sole.
14. The golf club head according to claim 9, wherein a maximum head
height is greater than or equal to 60 mm, and a maximum head width
is greater than or equal to 112 mm.
15. The golf club head according to claim 9, wherein a
center-of-gravity angle is greater than or equal to 15 degrees and
less than or equal to 40 degrees.
16. The golf club head according to claim 9, wherein a
center-of-gravity distance is greater than or equal to 35 mm and
less than or equal to 45 mm.
17. The golf club head according to claim 9, wherein a value
obtained by dividing the weight of the weight portion by the head
weight is greater than or equal to 0.09 and less than or equal to
0.19.
18. The golf club head according to claim 9, wherein a value
obtained by dividing a center-of-gravity distance by the head
weight is greater than or equal to 0.21.
19. The golf club head according to claim 9, wherein a value
obtained by dividing a center-of-gravity angle by the head weight
is greater than or equal to 0.13 and less than or equal to
0.17.
20. The golf club head according to claim 9, wherein the sole
includes a rib formed of a fiber-reinforced resin.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority to Japanese
Patent Application No. 2020-121409, filed on Jul. 15, 2020, and
Japanese Patent Application No. 2020-121410, filed on Jul. 15,
2020, the entire contents of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The disclosures herein relate to a golf club head.
2. Description of the Related Art
[0003] Conventionally, wood-type golf club heads including crowns,
faces, and soles are known. Such a golf club head may be formed
solely of a metallic material such as titanium. A wood-type golf
club head that is formed of a metallic material and a
fiber-reinforced resin (namely partially formed of a
fiber-reinforced resin) has also been proposed.
[0004] A golf club head that is at least partially formed of a
fiber-reinforced resin can be reduced in weight, increased in
volume, and so on as compared to a golf club head formed solely of
a metallic material. Therefore, the golf club head at least
partially formed of a fiber-reinforced resin can provide a greater
degree of freedom in design in many ways than a golf club head
formed solely of a metallic material.
[0005] However, it is difficult to decrease the weight of and
increase the volume of the golf club head while also improving ball
striking performance. RELATED-ART DOCUMENTS
PATENT DOCUMENTS
[0006] Patent Document 1: Japanese Patent No. 5459432
SUMMARY OF THE INVENTION
[0007] According to an aspect of the present disclosure, a golf
club head having a hollow structure is provided. The golf club head
includes a face, a body, and a weight portion. The body includes at
least a crown, a sole, and a hosel chamber. The crown, the sole,
and the hosel chamber include laminated layers of a
fiber-reinforced resin. The weight portion is formed of a material
having a specific gravity greater than specific gravities of the
crown and of the sole, and is disposed inward relative to a head
shell. The head volume is greater than or equal to 450 cc and less
than or equal to 470 cc. The head weight is less than or equal to
200 g. The average thickness of each of the crown and the sole is
greater than or equal to 0.7 mm. The weight of the weight portion
is greater than or equal to 20 g, and the weight portion is
attached to one or both of the crown and the sole.
[0008] According to another aspect of the present disclosure, a
golf club head having a hollow structure is provided. The golf club
head includes a face, a body, and a weight portion. The body
includes at least a crown, a sole, and a hosel chamber. The crown,
the sole, and the hosel chamber include laminated layers of a
fiber-reinforced resin. The weight portion is formed of a material
having a specific gravity greater than specific gravities of the
crown and of the sole, and is disposed inward relative to a head
shell. The head volume is greater than or equal to 450 cc and less
than or equal to 470 cc. The head weight is less than or equal to
180 g. The average thickness of each of the crown and the sole is
greater than or equal to 0.7 mm. The weight of the weight portion
is greater than or equal to 10 g, and the weight portion is
attached to one or both of the crown and the sole.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Other objects and further features of the present invention
will be apparent from the following detailed description when read
in conjunction with the accompanying drawings, in which:
[0010] FIG. 1 is a perspective view of a golf club head 1 according
to a first embodiment;
[0011] FIG. 2 is an exploded perspective view of the golf club head
1 according to the first embodiment;
[0012] FIG. 3 is a plan view of the golf club head 1 according to
the first embodiment;
[0013] FIG. 4 is a front view of a body of the golf club head 1
according to the first embodiment;
[0014] FIG. 5 is a partially enlarged cross-sectional view of the
golf club head 1 according to the first embodiment;
[0015] FIG. 6 is a perspective view of a golf club head 1A
according to a second embodiment;
[0016] FIG. 7 is an exploded perspective view of the golf club head
1A according to the second embodiment;
[0017] FIG. 8 is a plan view of the golf club head 1A according to
the second embodiment;
[0018] FIG. 9 is a front view of a body of the golf club head 1A
according to the second embodiment;
[0019] FIG. 10 is a partially enlarged cross-sectional view of the
golf club head 1A according to the second embodiment;
[0020] FIG. 11 is a plan view of a golf club head 1B according to a
third embodiment;
[0021] FIG. 12 is a front view of the body of the golf club head 1B
according to the third embodiment;
[0022] FIG. 13 is a plan view of a golf club head 1C according to a
fourth embodiment;
[0023] FIG. 14 is a front view of the body of the golf club head 1C
according to the fourth embodiment;
[0024] FIG. 15 is a perspective view of a golf club head 1D
according to a fifth embodiment;
[0025] FIG. 16 is a perspective view of the body of the golf club
head 1D according to the fifth embodiment;
[0026] FIG. 17 is a perspective view of a metal hosel 27;
[0027] FIG. 18 is a diagram illustrating a variable shaft
adjustability mechanism;
[0028] FIG. 19 is a perspective view of a golf club head 1E when
viewed from the bottom side according to a sixth embodiment;
[0029] FIG. 20 is a front view of the body of the golf club head 1E
according to the sixth embodiment;
[0030] FIG. 21 is a cross-sectional view (part 1) of the golf club
head 1E according to the sixth embodiment;
[0031] FIG. 22 is a cross-sectional view (part 2) of the golf club
head 1E according to the sixth embodiment;
[0032] FIG. 23 is a plan view of a golf club head 1F according to a
seventh embodiment;
[0033] FIG. 24 is a partially enlarged view of the golf club head
1F when viewed from the inner surface of a crown 21 according to
the seventh embodiment;
[0034] FIG. 25 is a diagram illustrating a specific configuration
of rigidity control portions of the crown 21;
[0035] FIG. 26 is a bottom view of the golf club head 1F according
to the seventh embodiment;
[0036] FIG. 27 is a front view of the body of the golf club head 1F
according to the seventh embodiment;
[0037] FIG. 28 is an exploded perspective view of a golf club head
1G according to an eighth embodiment; and
[0038] FIG. 29 is an exploded perspective view of a golf club head
1H according to the eighth embodiment.
DESCRIPTION OF THE EMBODIMENTS
[0039] According to an aspect of the present disclosure, a golf
club head at least partially formed of a fiber-reinforced resin can
be reduced in weight and increased in volume while also improving
ball striking performance.
[0040] In the following, embodiments of the present invention will
be described with reference to the accompanying drawings. In the
drawings, the same elements are denoted by the same reference
numerals and a duplicate description thereof may be omitted.
First Embodiment
[0041] FIG. 1 is a perspective view of a golf club head 1 according
to a first embodiment. FIG. 2 is an exploded perspective view of
the golf club head 1 according to the first embodiment. In FIG. 1,
the double-headed arrow d.sub.1 indicates the "toe-heel"
(left-right) direction, namely, the direction from the toe side to
the heel side or the direction from the heel side to the toe side,
of the golf club head 1, the double-headed arrow d.sub.2 indicates
the "crown-sole" (up-down) direction, namely, the direction from
the crown side to the sole side or the direction from the sole side
to the crown side, of the golf club head 1, and the double-headed
arrow d.sub.3 indicates the "face-back" (front-rear) direction,
namely, the direction from the face side to the back side or the
direction from the back side to the face side, of the golf club
head 1.
[0042] The golf club head 1 depicted in FIG. 1 and FIG. 2 is a
wood-type golf club head such as a driver club head. The golf club
head 1 includes a face 10 and a body 20, and has a hollow structure
in which the face 10 is joined to and integrated with the body
20.
[0043] The body 20 has an opening 201 on the face side of the golf
club head 1. A step, on which the face 10 is positioned, is formed
on the outer periphery of the opening 201 of the body 20. The face
10 is fitted to the step and joined to the body 20 so as to close
the opening 201. Note that the surface inside the hollow structure
may be referred to as an inner surface, and the surface outside the
hollow structure may be referred to as an outer surface.
[0044] The face 10 has a face surface 10f, which serves as a
ball-striking surface. The face 10 has a predetermined thickness,
and the face surface 10f forms the outer surface of the face 10.
The face 10 may be formed of titanium, a titanium alloy, stainless
steel, aluminum, an aluminum alloy, a ferrous metal, magnesium, a
magnesium alloy, or the like.
[0045] The face 10 may be formed of a fiber-reinforced resin. The
fiber-reinforced resin is a composite material of a resin and
fibers to serve as a reinforcing member. Examples of the fibers
constituting the fiber-reinforced resin include carbon fibers,
glass fibers, aramid fibers, polyethylene fibers, Zyron.RTM., and
boron fibers. Examples of the resin constituting the
fiber-reinforced resin include epoxy resins, phenolic resins,
polyester resins, and polycarbonate resins. For example, the face
10 can be formed of a carbon fiber-reinforced resin.
[0046] The body 20 includes a crown 21, a sole 22, and a hosel
chamber 23. The crown 21 defines a top portion of the golf club
head 1. The sole 22 defines a bottom portion of the golf club head
1. The hosel chamber 23 houses a hosel to which a shaft is coupled.
A back end 25 is of the body 20 located on the opposite side from
the face 10, and is a portion by which the crown 21 and the sole 22
are connected.
[0047] In the body 20, at least the crown 21, the sole 22, and the
hosel chamber 23 may be formed by laminating layers of a
fiber-reinforced resin. The crown 21, the sole 22, and the hosel
chamber 23 may be integrally formed by laminating layers of a
fiber-reinforced resin. For example, the crown 21, the sole 22, and
the hosel chamber 23 can be formed by laminating layers of a carbon
fiber-reinforced resin. Note that if the face 10 is formed of a
fiber-reinforced resin, the crown 21, the sole 22, and the hosel
chamber 23 may be formed of the same fiber-reinforced resin as the
face 10.
[0048] FIG. 3 is a plan view of the golf club head 1 according to
the first embodiment. FIG. 4 is a front view of the body of the
golf club head according to the first embodiment. FIG. 5 is a
partially enlarged cross-sectional view of the golf club head 1
according to the first embodiment. FIG. 5 depicts a cross section
of the golf club head 1 taken in a plane parallel to a horizontal
ground plane.
[0049] As illustrated in FIG. 3 through FIG. 5, the golf club head
1 includes a weight portion 70 in the vicinity of the back end 25
of the crown 21 and/or the sole 22. The weight portion 70 is
disposed to extend from the toe side to the heel side in the
toe-heel direction, and is disposed on the back end 25 side in the
face-back direction. For example, the weight portion 70 is disposed
such that the weight on the toe side of the weight portion 70 is
approximately equal to the weight on the heel side of the weight
portion 70.
[0050] In the golf club head 1, the weight portion 70 is attached
to the crown 21 and/or the sole 22. That is, the weight portion 70
may be provided on the crown 21 or may be provided on the sole 22.
Alternatively, the weight portion 70 may be provided across the
crown 21 and the sole 22.
[0051] The body 20 is formed of a fiber-reinforced resin 251. A
surface 70a of the weight portion 70 contacts the fiber-reinforced
resin 251, and a surface 70b of the weight portion 70 contacts a
fiber-reinforced resin 252. The fiber-reinforced resin 252 extends
along the surface 70b of the weight portion 70 and contacts the
fiber-reinforced resin 251, which forms the inner surface of the
crown 21 and/or the inner surface of the sole 22. The
fiber-reinforced resin 251 and/or fiber-reinforced resin 252 may
have a laminated structure of multiple layers of a fiber
reinforcement resin.
[0052] As described above, in the golf club head 1, the weight
portion 70 is disposed inward relative to a head shell 20a. The
weight portion 70 is sandwiched between adjacent fiber-reinforced
resin layers, and is not exposed to the inside of and the outside
of the body 20. The surface 70a of the weight portion 70 contacts
the head shell 20a, which serves as the inner surface of the
fiber-reinforced resin 251, and the surface 70b does not contact
the head shell 20a. At least one layer of the fiber-reinforced
resin 252 is provided on the surface 70b. Note that the head shell
20a serves as the inner surface of the body 20 when the weight
portion 70 is not attached.
[0053] The weight portion 70 is formed of a material having a
specific gravity greater than specific gravities of the crown 21
and of the sole 22, which are formed of a fiber reinforced resin.
Examples of the material of the weight portion 70 include stainless
steel, a stainless steel alloy, tungsten, a tungsten alloy, and
brass.
[0054] The volume of the golf club head 1 (hereinafter may be
referred to as a "head volume") is, for example, greater than or
equal to 450 cc and less than or equal to 470 cc, preferably
greater than or equal to 450 cc and less than or equal to 465 cc,
and more preferably greater than or equal to 455 cc and less than
or equal to 460 cc. The weight of the golf club head 1 including
the weight portion 70 (hereinafter may be referred to as a "head
weight") is, for example, greater than or equal to 180 g and less
than or equal to 200 g. In order to exhibit remarkable effects of
the weight portion 70, the weight of the weight portion 70 is
preferably 20% or more of the head weight. Specifically, the weight
of the weight portion 70 is greater than or equal to 20 g, and
preferably greater than or equal to 30 g and less than or equal to
55 g.
[0055] The maximum head height of the golf club head 1 is, for
example, greater than or equal to 60 mm. The maximum head width of
the golf club head 1 is, for example, greater than or equal to 112
mm. The maximum head height of the golf club head 1 is the height
from the lowest point of the sole 22 to the highest point of the
crown 21 when the golf club head 1 is placed in a reference state.
The maximum head width of the golf club head 1 is the width from
the leading edge to the maximum protrusion on the back side of the
golf club head 1.
[0056] For example, a characteristic time (CT), corresponding to
the coefficient of restitution of the face 10, of the golf club
head 1 is less than or equal to 257 .mu.s. Further, the average
thickness of the crown 21 and the average thickness of the sole 22
are both greater than or equal to 0.7 mm. The center-of-gravity
angle of the golf club head 1 is, for example, greater than or
equal to 25 degrees and less than or equal to 45 degrees. The
center-of-gravity distance of the golf club head 1 is, for example,
greater than or equal to 35 mm and less than or equal to 45 mm. As
used herein, the "average thickness" refers to the average value of
the thicknesses at 45 points selected from any 5 points in each of
9 flat areas, where a weight portion or a reinforcing portion (such
as a rib or a thick portion) is not formed, obtained by equally
dividing each of the crown 21 and the sole 22 into three areas in
the face-back direction and in the toe-heel direction.
[0057] The golf club head 1 can be manufactured by using a mold
assembly and a pressure forming device, for example. The mold
assembly can be assembled and disassembled, and the pressure
forming device includes an openable sealed container, and a
pneumatic mechanism and a heating mechanism installed in the
openable sealed container.
[0058] Specifically, the golf club head 1 may be manufactured by a
method as described below. First, a mold assembly that can be
assembled and disassembled is prepared. Then, a plurality of layers
of prepregs formed of a fiber-reinforced resin are prepared, and
the prepregs are attached to the mold assembly so as to be
laminated to form a blank of the body 20.
[0059] In order to form the weight portion 70 integrally with a
fiber-reinforced resin of the crown 21 and/or the sole 22, the
weight portion 70 may be placed within the blank of the body 20
when the blank of the body 20 is formed by attaching the plurality
of prepregs to the mold assembly such that the prepregs are
laminated. Specifically, the weight portion 70 may be bonded to the
prepregs, or the weight portion 70 may be covered by the
prepregs.
[0060] Next, the mold assembly including the blank of the body 20
is placed into a bag. The bag is placed in the openable sealed
container, and heat is applied by the heating mechanism while a
vacuum is created by the pneumatic mechanism. In this manner, the
prepregs formed of the fiber-reinforced resin, which constitute the
blank of the body 20, are cured by a cross-linking reaction. After
the heating, the body 20 is bonded to the preformed face 10 to form
a semi-finished golf club head. The semi-finished golf club head is
deburred and subjected to surface finishing to obtain the golf club
head 1.
[0061] In the above-described method, when heat is applied by the
heating mechanism while a vacuum is created by the pneumatic
mechanism, the vacuum pressure value can be set in a range from
-0.1 mbar to -1000 mbar, the heating temperature can be set in a
range from 40.degree. C. to 250.degree. C., and the vacuum
treatment and heating time can be set in a range from 1 minute to
60 minutes.
[0062] An autoclave may be used as the pressure forming device. If
an autoclave is used as the pressure forming device, the autoclave
is able to heat, evacuate air, and apply positive air pressure to a
blank of the golf club head 1. For example, a positive air pressure
value may be set in a range from 2 bar to 100 bar.
[0063] Further, the vacuum, the heating temperature, and the
positive air pressure may be adjusted in accordance with the shape
of a wood-type golf club head, the thickness of prepregs formed of
a fiber-reinforced resin, or the like. Further, the vacuum pressure
value, the heating temperature, and the positive air pressure value
may also be adjusted in accordance with the cross-linking reaction
of prepregs formed of a fiber-reinforced resin. That is, the shape
and weight of a golf club head can be readily controlled by using a
fiber-reinforced resin as the material of the body.
[0064] Table 1 and Table 2 below indicate examples of function
values of conventional golf club head (driver club head) models
recently put on the market. Note that although the weight of model
F is as light as 182.8 g, this model is designed for senior citizen
use. The values in Table 1 and Table 2 are obtained by actually
measuring the conventional golf club heads.
TABLE-US-00001 TABLE 1 FUNCTION MODEL MODEL MODEL MODEL MODEL MODEL
VALUE A B C D E F HEAD 201.2 196.0 193.2 201.8 199.2 182.8 WEIGHT
[g] CENTER-OF- 33.7 34.2 38.4 33.0 39.0 34.7 GRAVITY DEPTH [mm]
MOMENT OF 4489.0 3925.0 4846.0 4309.0 4845.0 3832.0 INERTIA Y [g
cm.sup.2] CENTER-OF- 39.3 47.0 51.3 42.3 46.8 38.9 GRAVITY DISTANCE
[mm] CENTER-OF- 28.0 22.0 28.0 25.0 29.0 33.0 GRAVITY ANGLE
[DEGREE] HEAD 441.0 458.0 453.0 456.0 462.0 446.0 VOLUME [cc]
TABLE-US-00002 TABLE 2 FUNCTION MODEL MODEL MODEL MODEL MODEL MODEL
VALUE G H I J K L HEAD 202.7 194.8 193.9 202.6 195.0 194.1 WEIGHT
[g] CENTER-OF- 32.8 34.5 38.4 40.5 32.9 30.6 GRAVITY DEPTH [mm]
MOMENT OF 4437.0 4464.0 4647.0 5439.0 4398.0 3869.0 INERTIA Y [g
cm.sup.2] CENTER-OF- 41.1 46.8 47.7 57.4 42.6 36.5 GRAVITY DISTANCE
[mm] CENTER-OF- 25.0 26.0 28.0 29.0 26.0 29.0 GRAVITY ANGLE
[DEGREE] HEAD 459.0 451.0 456.0 454.0 448.0 454.0 VOLUME [cc]
[0065] Conversely, Table 3 indicates examples of function values of
the golf club head 1 according to the first embodiment. In Table 3,
the moment of inertia X indicates the moment of inertia in the
face-back direction, and the moment of inertia Y indicates the
moment of inertia in the toe-heel direction. Note that the values
in Table 3 are obtained from computer aided design (CAD) data.
[0066] In Table 3, the head volume of each of model M and model N
is greater than or equal to 450 cc and less than or equal to 470
cc, and the head weight is less than or equal to 200 g. In each of
the model M and the model N, even if the head weight is light,
sufficiently high moments of inertia can be obtained. Further,
although the center-of-gravity distance is 40 mm or less, the
moments of inertia are high and the center-of-gravity angle is
large.
TABLE-US-00003 TABLE 3 FUNCTION MODEL MODEL VALUE M N HEAD 192.0
182.0 WEIGHT [g] WEIGHT OF 45.3 35.3 WEIGHT PORTION [g] CENTER-OF-
39.9 36.9 GRAVITY DEPTH [mm] MOMENT OF 3457.0 3130.0 INERTIA X [g
cm.sup.2] MOMENT OF 4819.0 4472.0 INERTIA Y [g cm.sup.2] CENTER-OF-
39.5 38.3 GRAVITY DISTANCE [mm] CENTER-OF- 35.2 31.3 GRAVITY ANGLE
[DEGREE] HEAD 455 455 VOLUME [cc]
[0067] In the case of titanium driver club heads recently put on
the market, the average thickness of a crown is approximately 0.5
mm to 0.7 mm and the average thickness of a sole is approximately
0.8 mm. For such a golf club head, in order to secure additional
weight to enable a unique design, it would be required to reduce
the weight of a part of the golf club head so as to avoid an
increase in the entire head weight. Because the coefficient of
restitution of a face is limited by the official rules of golf,
reducing the weight of the face would be difficult. Therefore, the
weight of the crown or the sole would need to be reduced.
[0068] That is, if the weight of the face is reduced by reducing
the thickness of the face, the coefficient of resilience of the
face would increase due to the reduced thickness. As a result, the
CT, corresponding to the coefficient of restitution of the face,
would be highly likely to exceed 257 .mu.s, which is the limit on
spring-like effect (SLE) set by the Royal and Ancient Golf Club of
St Andrews (R&A). For this reason, the weight of the crown or
the sole would need to be reduced.
[0069] However, for conventional driver club heads, there is a
limitation on reducing the thickness of the crown or the sole while
securing strength, and thus, it would be difficult to have large
additional weight while maintaining certain thicknesses of the
crown and the sole. Conversely, in the golf club head 1 according
to the first embodiment, because the crown 21, the sole 22, and the
hosel chamber 23 are formed by laminating layers of a
fiber-reinforced resin, additional weight can be readily secured as
compared to the conventional driver club heads.
[0070] Specifically, a weight of 20 g or more can be added to the
golf club head 1 even when each of the crown 21 and the sole 22 has
the average thickness of 0.7 mm or more. That is, a weight of 20 g
or more can be added to the weight portion 70. In other words, the
weight portion 70 with a weight of 20 g or more can be attached to
the crown 21 and/or the sole 22. Accordingly, as can be seen from
Table 3, even if the head weight is 200 g or less, the golf club
head 1 having a sufficiently large head volume with high moments of
inertia can be provided.
[0071] The moment of inertia Y is preferably greater than or equal
to 4000 gcm.sup.2 and less than or equal to 6000 gcm.sup.2, and
more preferably greater than or equal to 4350 gcm.sup.2 and less
than or equal to 5200 gcm.sup.2. The center-of-gravity angle is
preferably greater than or equal to 25 degrees and less than or
equal to 45 degrees, and more preferably greater than or equal to
30 degrees and less than or equal to 40 degrees.
[0072] Among the conventional golf club heads, a golf club head
whose moment of inertia Y per head weight is close to that of the
golf club head 1 has a small center-of-gravity angle, and a golf
club head whose center-of-gravity angle per head weight is close to
that of the golf club head 1 has a low moment of inertia Y. That
is, unlike the conventional golf club heads, in the golf club head
1, both the moment of inertia Y per head weight and the
center-of-gravity angle per head weight can be largely increased at
the same time.
[0073] As can be calculated from the functional values indicated in
Table 3, a value obtained by dividing the weight of the weight
portion 70 by the head weight of the golf club head 1 can be
greater than or equal to 0.19 and less than or equal to 0.24.
Further, a value obtained by dividing the center-of-gravity
distance by the head weight of the golf club head 1 can be greater
than or equal to 0.20. Further, a value obtained by dividing the
center-of-gravity angle by the head weight of the golf club head 1
can be greater than or equal to 0.17 and less than or equal to
0.19.
[0074] Accordingly, in the golf club head 1, because the crown 21,
the sole 22, and the hosel chamber 23 are formed by laminating
layers of a fiber-reinforced resin, the head weight can be reduced.
That is, the golf club head 1 whose head volume is greater than or
equal to 450 cc and less than or equal to 470 cc and whose head
weight is less than or equal to 200 g can be provided. In addition,
the average thickness of each of the crown 21 and the sole 22 can
be 0.7 mm or more, thus allowing the strength of each of the crown
21 and the sole 22 to be sufficiently maintained.
[0075] Further, in the golf club head 1, the crown 21, the sole 22,
and the hosel chamber 23 are integrally formed by laminating layers
of a fiber-reinforced resin with a high strength-to-weight ratio,
thus allowing additional weight to be readily secured as compared
to the conventional golf club heads. Further, the weight portion 70
can be readily provided at any position of the crown 21 and/or the
sole 22 by sandwiching the weight portion 70 between adjacent
fiber-reinforced resin layers.
[0076] Accordingly, various designs using the weight portion 70 are
possible. For example, effects of increasing the head speed
associated with a reduction in the head weight can be exhibited
while also preventing a deterioration in performance due to the
reduction in the head weight. As an example, in the golf club head
1, the weight portion 70 is disposed to extend from the toe side to
the heel side in the toe-heel direction, and is disposed on the
back end 25 side in the face-back direction. In addition, the
weight portion 70 is disposed such that the weight on the toe side
of the weight portion 70 is approximately equal to the weight on
the heel side of the weight portion 70.
[0077] Accordingly, although the weight of the golf club head 1 is
less than or equal to 200 g, the moments of inertia can be
increased, thereby increasing the stability of the head and the
straightness of the ball trajectory. As a result, in the golf club
head 1, the rotation of the head when mishitting a golf ball can be
suppressed and thus slicing can be avoided.
Second Embodiment
[0078] In the following, a golf club head 1A according to a second
embodiment will be described. In the second embodiment, differences
from the first embodiment will be described, and descriptions of
elements having the same configuration and functions as those of
the first embodiment may be omitted.
[0079] FIG. 6 is a perspective view of the golf club head 1A
according to the second embodiment. FIG. 7 is an exploded
perspective view of the golf club head 1A according to the second
embodiment.
[0080] The golf club head 1A depicted in FIG. 6 and FIG. 7 is a
wood-type golf club head such as a driver club head. The golf club
head 1A includes a face 10 and a body 20, and has a hollow
structure in which the face 10 is joined to and integrated with the
body 20.
[0081] The body 20 includes a crown 21, a sole 22, and a hosel
chamber 23. In the body 20, at least the crown 21, the sole 22, and
the hosel chamber 23 may be formed by laminating layers of a
fiber-reinforced resin. The crown 21, the sole 22, and the hosel
chamber 23 may be integrally formed by laminating layers of a
fiber-reinforced resin. For example, the crown 21, the sole 22, and
the hosel chamber 23 can be formed by laminating layers of a carbon
fiber-reinforced resin. Note that if the face 10 is formed of a
fiber-reinforced resin, the crown 21, the sole 22, and the hosel
chamber 23 may be formed of the same fiber-reinforced resin as the
face 10.
[0082] FIG. 8 is a plan view of the golf club head 1A according to
the second embodiment. FIG. 9 is a front view of the body of the
golf club head 1A according to the second embodiment. FIG. 10 is a
partially enlarged cross-sectional view of the golf club head 1A
according to the second embodiment. FIG. 10 depicts a cross section
of the golf club head 1A taken in a plane parallel to a horizontal
ground plane.
[0083] Similar to the first embodiment, as illustrated in FIG. 8
through FIG. 10, the golf club head 1A includes a weight portion 70
in the vicinity of the back end 25 of the crown 21 and/or the sole
22. The weight portion 70 is disposed to extend from the toe side
to the heel side in the toe-heel direction, and is disposed on the
back end 25 side in the face-back direction. For example, the
weight portion 70 is disposed such that the weight on the toe side
of the weight portion 70 is approximately equal to the weight on
the heel side of the weight portion 70.
[0084] In the golf club head 1A, the weight portion 70 is attached
to the crown 21 and/or the sole 22. That is, the weight portion 70
may be provided on the crown 21 or may be provided on the sole 22.
Alternatively, the weight portion 70 may be provided across the
crown 21 and the sole 22.
[0085] The body 20 is formed of a fiber-reinforced resin 251. A
surface 70a of the weight portion 70 contacts the fiber-reinforced
resin 251, and a surface 70b of the weight portion 70 contacts a
fiber-reinforced resin 252. The fiber-reinforced resin 252 extends
along the surface 70b of the weight portion 70 and contacts the
fiber-reinforced resin 251, which forms the inner surface of the
crown 21 and/or the inner surface of the sole 22. The
fiber-reinforced resin 251 and/or fiber-reinforced resin 252 may
have a laminated structure of multiple layers of a fiber
reinforcement resin.
[0086] As described above, in the golf club head 1, the weight
portion 70 is disposed inward relative to a head shell 20a. The
weight portion 70 is sandwiched between adjacent fiber-reinforced
resin layers, and is not exposed to the inside of and the outside
of the body 20. The surface 70a of the weight portion 70 contacts
the head shell 20a, which serves as the inner surface of the
fiber-reinforced resin 251, and the surface 70b does not contact
the head shell 20a. The surface 70b has at least one layer of the
fiber-reinforced resin 252. Note that the head shell 20a serves as
the inner surface of the body 20 when the weight portion 70 is not
attached.
[0087] The weight portion 70 is formed of a material having a
specific gravity greater than specific gravities of the crown 21
and of the sole 22, which are formed of a fiber reinforced resin.
Examples of the material of the weight portion 70 include stainless
steel, a stainless steel alloy, tungsten, a tungsten alloy, and
brass.
[0088] The volume of the golf club head 1A (hereinafter may be
referred to as a "head volume") is, for example, greater than or
equal to 450 cc and less than or equal to 470 cc, preferably
greater than or equal to 450 cc and less than or equal to 465 cc,
and more preferably greater than or equal to 455 cc and less than
or equal to 460 cc. The weight of the golf club head 1A including
the weight portion 70 (hereinafter may be referred to as a "head
weight") is, for example, greater than or equal to 160 g and less
than or equal to 180 g. In order to exhibit remarkable effects of
the weight portion 70, the weight of the weight portion 70 may be
greater than or equal to 10 g and less than or equal to 35 g.
[0089] The maximum head height of the golf club head 1A is, for
example, greater than or equal to 60 mm. The maximum head width of
the golf club head 1A is, for example, greater than or equal to 112
mm. The maximum head height of the golf club head 1A is the height
from the lowest point of the sole 22 to the highest point of the
crown 21 when the golf club head 1A is placed in a reference state.
The maximum head width of the golf club head 1A is the width from
the leading edge to the maximum protrusion on the back side of the
golf club head 1A.
[0090] For example, a characteristic time (CT), corresponding to
the coefficient of restitution of the face 10, of the golf club
head 1A is less than or equal to 257 .mu.s. Further, the average
thickness of the crown 21 and the average thickness of the sole 22
are both greater than or equal to 0.7 mm. The center-of-gravity
angle of the golf club head 1A is, for example, greater than or
equal to 15 degrees and less than or equal to 40 degrees. The
center-of-gravity distance of the golf club head 1A is, for
example, greater than or equal to 35 mm and less than or equal to
45 mm.
[0091] The golf club head 1A according to the second embodiment can
be manufactured in the same manner as that described in the first
embodiment.
[0092] Table 4 below indicates examples of function values of the
golf club head 1A according to the second embodiment. In Table 4,
the moment of inertia X indicates the moment of inertia in the
face-back direction, and the moment of inertia Y indicates the
moment of inertia in the toe-heel direction. Note that the values
in Table 4 are obtained from CAD data.
[0093] In Table 4, the head volume of each of model O and model P
is greater than or equal to 450 cc and less than or equal to 470
cc, and the head weight is less than or equal to 180 g. In the
conventional golf club heads whose head volumes are approximately
440 cc to 160 cc as indicated in Table 1 and Table 2 above, the
head weights are approximately 180 g to 200 g, and no conventional
golf club head has a weight as light as 180 g or less. In each of
the model O and the model P, even if the head weight is light,
sufficiently high moments of inertia can be obtained. In addition,
the center-of-gravity depth and center-of-gravity angle indicate
values comparable to those of the models A through L each having a
weight greater than 180 g. Further, although the center-of-gravity
distance is 40 mm or less, the moments of inertia are high and the
center-of-gravity angle is large.
TABLE-US-00004 TABLE 4 FUNCTION MODEL MODEL VALUE O P HEAD 172.0
162.0 WEIGHT [g] WEIGHT OF 25.3 15.3 WEIGHT PORTION [g] CENTER-OF-
33.5 29.7 GRAVITY DEPTH [mm] MOMENT OF 2761.0 2349.0 INERTIA X [g
cm.sup.2] MOMENT OF 4082.0 3649.0 INERTIA Y [g cm.sup.2] CENTER-OF-
37.2 36.4 GRAVITY DISTANCE [mm] CENTER-OF- 26.7 21.5 GRAVITY ANGLE
[DEGREE] HEAD 455 455 VOLUME [cc]
[0094] In the case of titanium driver club heads recently put on
the market, the average thickness of a crown is approximately 0.5
mm to 0.7 mm and the average thickness of a sole is approximately
0.8 mm. For such a golf club head, in order to secure additional
weight to enable a unique design, it would be required to reduce
the weight of a part of the golf club head so as to avoid an
increase in the entire head weight. Because of the coefficient of
restitution of a face by the official rules of golf, reducing the
weight of the face would be difficult. Therefore, the weight of the
crown or the sole would need to be reduced.
[0095] That is, if the weight of the face is reduced by reducing
the thickness of the face, the coefficient of resilience of the
face would increase due to the reduced thickness. As a result, the
CT, corresponding to the coefficient of restitution of the face,
would be highly likely to exceed 257 .mu.s, which is the limit on
spring-like effect (SLE) set by the Royal and Ancient Golf Club of
St Andrews (R&A). For this reason, the weight of the crown or
the sole would need to be reduced.
[0096] However, for conventional driver club heads, there is a
limitation on reducing the thickness of the crown or the sole while
securing strength, and thus, it would be difficult to have large
additional weight while maintaining certain thicknesses of the
crown and the sole. Conversely, in the golf club head 1A according
to the second embodiment, because the crown 21, the sole 22, and
the hosel chamber 23 are formed by laminating layers of a
fiber-reinforced resin, additional weight can be readily secured as
compared to the conventional driver club heads.
[0097] Specifically, a weight of 10 g or more can be added to the
golf club head 1A even when each of the crown 21 and the sole 22
has the average thickness of 0.7 mm or more. That is, a weight of
10 g or more can be added to the weight portion 70. In other words,
the weight portion 70 with a weight of 10 g or more can be attached
to the crown 21 and/or the sole 22. Accordingly, as can be seen
from Table 4, even if the head weight is 180 g or less, the golf
club head 1A having a sufficiently large head volume with high
moments of inertia can be provided.
[0098] The moment of inertia Y is preferably greater than or equal
to 3000 gcm.sup.2 and less than or equal to 4000 gcm.sup.2, and
more preferably greater than or equal to 3550 gcm.sup.2 and less
than or equal to 4400 gcm.sup.2. The center-of-gravity angle is
preferably greater than or equal to 15 degrees and less than or
equal to 40 degrees, and more preferably greater than or equal to
20 degrees and less than or equal to 30 degrees.
[0099] Among the conventional golf club heads, a golf club head
whose moment of inertia Y per head weight is close to that of the
golf club head 1A has a small center-of-gravity angle, and a golf
club head whose center-of-gravity angle per head weight is close to
that of the golf club head 1A has a low moment of inertia Y. That
is, unlike the conventional golf club heads, in the golf club head
1A, both the moment of inertia Y per head weight and the
center-of-gravity angle per head weight can be largely increased at
the same time.
[0100] As can be calculated from the functional values indicated in
Table 4, a value obtained by dividing the weight of the weight
portion 70 by the head weight of the golf club head 1A can be
greater than or equal to 0.09 and less than or equal to 0.19.
Further, a value obtained by dividing the center-of-gravity
distance by the head weight of the golf club head 1A can be greater
than or equal to 0.21. Further, a value obtained by dividing the
center-of-gravity angle by the head weight of the golf club head 1A
can be greater than or equal to 0.13 and less than or equal to
0.17.
[0101] Accordingly, in the golf club head 1A, because the crown 21,
the sole 22, and the hosel chamber 23 are formed by laminating
layers of a fiber-reinforced resin, the head weight can be reduced.
That is, the golf club head 1A whose head volume is greater than or
equal to 450 cc and less than or equal to 470 cc and whose head
weight is less than or equal to 180 g can be provided. In addition,
the average thickness of each of the crown 21 and the sole 22 can
be 0.7 mm or more, thus allowing the strength of each of the crown
21 and the sole 22 to be sufficiently maintained.
[0102] Further, in the golf club head 1A, the crown 21, the sole
22, and the hosel chamber 23 are integrally formed by laminating
layers of a fiber-reinforced resin with a high strength-to-weight
ratio, thus allowing additional weight to be readily secured as
compared to the conventional golf club heads. Further, the weight
portion 70 can be readily provided at any position of the crown 21
and/or the sole 22 by sandwiching the weight portion 70 between
adjacent fiber-reinforced resin layers.
[0103] Accordingly, various designs using the weight portion 70 are
possible. For example, effects of increasing the head speed
associated with a reduction in the head weight can be exhibited
while also preventing a deterioration in performance due to the
reduction in the head weight. As an example, in the golf club head
1A, the weight portion 70 is disposed to extend from the toe side
to the heel side in the toe-heel direction, and is disposed on the
back end 25 side in the face-back direction. In addition, the
weight portion 70 is disposed such that the weight on the toe side
of the weight portion 70 is approximately equal to the weight on
the heel side of the weight portion 70. Accordingly, although the
weight of the golf club head 1A is less than or equal to 180 g, the
moments of inertia can be increased, thereby increasing the
stability of the head and the straightness of the ball trajectory.
As a result, in the golf club head 1A, the rotation of the head
when mishitting a golf ball can be suppressed and thus slicing can
be avoided.
Third Embodiment
[0104] A third embodiment depicts an example of a golf club head in
which a weight portion is provided at a different position from
that of the above-described embodiments. In the third embodiment,
descriptions of elements identical to those in the above-described
embodiments may be omitted.
[0105] FIG. 11 is a plan view of a golf club head 1B according to
the third embodiment. FIG. 12 is a front view of the body of the
golf club head 1B according to the third embodiment.
[0106] As illustrated in FIG. 11 and FIG. 12, the golf club head 1B
includes a weight portion 71 in the vicinity of the back end 25 of
the crown 21 and/or the sole 22. In the golf club head 1B, the
weight portion 71 may be provided on the crown 21 or may be
provided on the sole 22. Alternatively, the weight portion 71 may
be provided across the crown 21 and the sole 22.
[0107] The weight portion 71 is located closer to the heel side
than to the toe side in the toe-heel direction, and is located on
the back end 25 side in the face-back direction. For example, the
weight portion 71 is disposed such that the weight of the weight
portion 71 is greater on the heel side than on the toe side.
[0108] The volume, the weight, the maximum head height, the maximum
head width, the CT, the average thickness of the crown 21, and the
average thickness of the sole 22 of the golf club head 1B are
similar to those of the golf club head 1. Further, the material and
the weight of the weight portion 71 are similar to those of the
weight portion 70.
[0109] Accordingly, in the golf club head 1B, because the crown 21,
the sole 22, and the hosel chamber 23 are formed by laminating
layers of a fiber-reinforced resin, the head weight can be reduced.
That is, the golf club head 1B whose head volume is greater than or
equal to 450 cc and less than or equal to 470 cc and whose head
weight is less than or equal to 200 g or less than or equal to 180
g can be provided. In addition, the average thickness of each of
the crown 21 and the sole 22 can be 0.7 mm or more, thus allowing
the strength of each of the crown 21 and the sole 22 to be
sufficiently maintained.
[0110] Further, similar to the above-described embodiments, in the
golf club head 1B, the crown 21, the sole 22, and the hosel chamber
23 are formed by laminating layers of a fiber-reinforced resin,
thus allowing additional weight to be readily secured as compared
to the conventional golf club heads. Further, the weight portion 71
can be readily provided at the crown 21 and/or the sole 22 by
sandwiching the weight portion 71 between adjacent fiber-reinforced
resin layers.
[0111] Accordingly, various designs using the weight portion 71 are
possible. For example, a deterioration in performance due to a
reduction in the head weight can be prevented. As an example, in
the golf club head 1B, the weight portion 71 is disposed closer to
the heel side than to the toe side in the toe-heel direction, and
is disposed on the back end 25 side in the face-back direction.
Therefore, in the golf club head 1B, the center-of-gravity angle
can be increased, thus improving catchability when striking a golf
ball. As a result, slicing can be avoided and a draw can be readily
hit.
Fourth Embodiment
[0112] A fourth embodiment depicts another example of a golf club
head in which a weight portion is provided at a different position
from that of the first embodiment. In the fourth embodiment,
descriptions of elements identical to those in the above-described
embodiments may be omitted.
[0113] FIG. 13 is a plan view of a golf club head 10 according to
the fourth embodiment. FIG. 14 is a front view of the body of the
golf club head 10 according to the fourth embodiment.
[0114] As illustrated in FIG. 13 and FIG. 14, the golf club head 10
includes a weight portion 72 in the vicinity of the back end 25 of
the crown 21 and/or the sole 22. In the golf club head 1C, the
weight portion 72 may be provided on the crown 21 or may be
provided on the sole 22. Alternatively, the weight portion 71 may
be provided across the crown 21 and the sole 22.
[0115] The weight portion 72 is disposed to extend from the toe
side to the heel side in the toe-heel direction, and is located on
the back end 25 side in the face-back direction. For example, the
weight portion 72 is disposed such that the weight of the weight
portion 72 is greater on the heel side than on the toe side. That
is, the weight portion 72 has a shape as if the weight portion 71
is added to the weight portion 70.
[0116] The volume, the weight, the maximum head height, the maximum
head width, the CT, the average thickness of the crown 21, and the
average thickness of the sole 22 of the golf club head 1C are
similar to those of the golf club head 1. Further, the material and
the weight of the weight portion 72 are similar to those of the
weight portion 70.
[0117] Similar to the above-described embodiments, in the golf club
head 1C, because the crown 21, the sole 22, and the hosel chamber
23 are formed by laminating layers of a fiber-reinforced resin, the
head weight can be reduced. That is, the golf club head 10 whose
head volume is greater than or equal to 450 and less than or equal
to 470 cc and whose head weight is less than or equal to 200 g or
less than or equal to 180 g can be provided. In addition, the
average thickness of each of the crown 21 and the sole 22 can be
0.7 mm or more, thus allowing the strength of each of the crown 21
and the sole 22 to be sufficiently maintained.
[0118] Further, similar to the above-described embodiments, in the
golf club head 1C, the crown 21, the sole 22, and the hosel chamber
23 are formed by laminating layers of a fiber-reinforced resin,
thus allowing additional weight to be readily secured as compared
to the conventional golf club heads. Further, the weight portion 72
can be readily provided at the crown 21 and/or the sole 22 by
sandwiching the weight portion 72 between adjacent fiber-reinforced
resin layers.
[0119] Accordingly, various designs using the weight portion 72 are
possible. For example, a deterioration in performance due to a
reduction in the head weight can be prevented. As an example, in
the golf club head 1C, the weight portion 72 is disposed to extend
from the toe side to the heel side in the toe-heel direction, and
is disposed on the back end 25 side in the face-back direction. In
addition, the weight portion 72 is disposed such that the weight of
the weight portion 72 is greater on the heel side than on the toe
side. Accordingly, in the golf club head 1C, although head weight
is less than or equal to 200 g or less than or equal to 180 g, the
moments of inertia can be increased, thereby increasing the
stability of the golf club head 1C and the straightness of the ball
trajectory. As a result, in the golf club head 1C, the rotation of
the head when mishitting a golf ball can be suppressed and thus
slicing can be avoided. Further, in the golf club head 1C, the
center-of-gravity angle can be increased, thus improving
catchability when striking a golf ball. As a result, slicing can be
avoided and a draw can be readily hit.
[0120] The golf club heads 1 through 10 can be manufactured by
using the same mold assembly. A weight portion may be disposed at
any location in a blank of a body. That is, various function values
can be achieved by using the same mold assembly and simply changing
the size, the weight, or the position of the weight portion. The
above-described high moments of inertia and high center-of-gravity
angle are merely examples. By using the same mold assembly and
simply changing the size, the weight, or the position of the weight
portion, various characteristics can be achieved in accordance with
the requirements of a golfer, such as a low center of gravity
(easiness in hitting high balls and a low spin rate) and a forward
center of gravity (a low spin rate and a strong ballistic
trajectory). In addition, golf club heads having various
characteristics are expected to be used for fitting.
Fifth Embodiment
[0121] A fifth embodiment depicts an example of a golf club head in
which a metal hosel is attached to the hosel chamber 23. In the
fifth embodiment, descriptions of elements identical to those in
the above-described embodiments may be omitted.
[0122] FIG. 15 is a perspective view of a golf club head 1D
according to the fifth embodiment. FIG. 16 is a perspective view of
the body of the golf club head 1D according to the fifth
embodiment. FIG. 17 FIG. 17 is a perspective view of a metal hosel
27.
[0123] As illustrated in FIG. 15 through FIG. 17, in the golf club
head 1D, at least the crown 21, the sole 22, and the hosel chamber
23 of the body 20 are formed by laminating layers of a
fiber-reinforced resin.
[0124] In the golf club head 1D, the hosel chamber 23 extends
through the body 20 and to the sole 22. The hosel chamber 23 has a
hollow cylindrical shape and houses the metal hosel 27. A large
diameter portion on one end side of the metal hosel 27 is exposed
from the hosel chamber 23. A portion of the hosel chamber 23
located within the body 20 is cut out to expose the side surface of
the metal hosel 27.
[0125] The metal hosel 27 may be a member having a hollow
cylindrical shape. For example, titanium, a titanium alloy,
aluminum, an aluminum alloy, tungsten, a tungsten alloy, stainless
steel, or the like may be used as the material of the metal hosel
27. The metal hosel 27 may be integrally formed with the
fiber-reinforced resin included in the body 20.
[0126] In order to form the metal hosel 27 integrally with the
fiber-reinforced resin included in the body 20, the metal hosel 27
may be placed within a blank of the body 20 when the blank of the
body 20 is formed by attaching a plurality of prepregs to a mold
assembly such that the plurality of prepregs are laminated.
Specifically, the metal hosel 27 may be bonded to the prepregs, or
the metal hosel 27 may be covered by the prepregs.
[0127] In this manner, in the golf club head 1D, at least the crown
21, the sole 22, and the hosel chamber 23 of the body 20 are formed
by laminating layers of a fiber-reinforced resin. Therefore, the
metal hosel 27 can be readily embedded into the body 20. By
embedding the metal hosel 27, the strength of the metal hosel 27
can be enhanced as compared to when a hosel formed of a resin is
used.
[0128] The golf club head 1D may have a variable shaft
adjustability mechanism. The variable shaft adjustability mechanism
may include the metal hosel 27, a shaft case 28, and an attachment
screw 29 as illustrated in FIG. 18. Specifically, the shaft case 28
is housed within the metal hosel 27 and is removably attached to
the metal hosel 27 by the attachment screw 29 from the sole 22
side. For example, the shaft case 28 may be affixed to a shaft with
an adhesive.
[0129] One or both of a hole of the metal hosel 27 and a hole of
the shaft case 28 may be eccentric. Therefore, attaching the shaft
case 28 to the metal hosel 27 by causing the shaft case 28 to
rotate in a circumferential direction allows the positional
relationship between the golf club head 1D and the shaft (for
example, a lie angle, a face angle, and the like) to be
adjusted.
[0130] Accordingly, in the golf club head 10, the crown 21, the
sole 22, and the hosel chamber 23 are formed by laminating layers
of a fiber-reinforced resin, thus allowing additional weight to be
readily secured as compared to the conventional golf club heads. As
a result, the additional weight can be added to the metal hosel 27
or the shaft case 28 constituting the variable shaft adjustability
mechanism.
Sixth Embodiment
[0131] A sixth embodiment depicts an example of a golf club head
that includes a connector to which/from which a rod is
attachable/detachable. In the sixth embodiment, descriptions of
elements identical to those in the above-described embodiments may
be omitted.
[0132] FIG. 19 is a perspective view of a golf club head 1E when
viewed from the bottom side according to the sixth embodiment. FIG.
20 is a front view of the body of the golf club head 1E according
to the sixth embodiment. As illustrated in FIG. 19 and FIG. 20, a
recessed portion 222 is provided in the sole 22 of the golf club
head 1E. The recessed portion 222 is recessed from the outer
surface side toward the inner surface side of the sole 22. The
recessed portion 222 includes a connector 223 that is made of metal
and to which/from which a rod 90 is attachable/detachable. The face
10 is, for example, made of metal, and the face 10 is apart from
the connector 223. FIG. 19 and FIG. 20 depict a state in which the
rod 90 is not attached to the connector 223.
[0133] The connector 223 is formed integrally with a
fiber-reinforced resin of the sole 22. In order to form the
connector 223 integrally with the fiber-reinforced resin of the
sole 22, the connector 223 may be placed within a blank of the body
20 when the blank of the body 20 is formed by attaching a plurality
of prepregs to a mold assembly such that the plurality of prepregs
are laminated. Specifically, the connector 223 may be bonded to the
prepregs, or the connector 223 may be covered by the prepregs.
[0134] The connector 223 includes a female thread 224. The
connector 223 is located approximately at the center of the sole 22
in the toe-heel direction, and is located on the face 10 side of
the sole 22 in the face-back direction. For example, titanium, a
titanium alloy, aluminum, an aluminum alloy, tungsten, a tungsten
alloy, stainless steel, or the like may be used as the material of
the connector 223.
[0135] FIG. 21 is a cross-sectional view (part 1) of the golf club
head 1E according to the sixth embodiment. In FIG. 21, the rod 90
is attached to the connector 223. The rod 90 illustrated in FIG. 21
is attachable to and detachable from the connector 223. For
example, the rod 90 includes a head 91, a male thread 92, a
cylindrical portion 93, and a cap 94. The male thread 92 is
provided on one side of the head 91 concentrically with the head
91. The cylindrical portion 93 is provided on one side of the male
thread 92 concentrically with the head 91 and the male thread 92.
The tip side of the cylindrical portion 93 is reduced in diameter
and is covered by the cap 94.
[0136] For example, a metallic material such as titanium, a
titanium alloy, aluminum, tungsten, a tungsten alloy, stainless
steel, or a ferrous metal may be used as the material of each of
the head 91, the male thread 92, and the cylindrical portion 93.
For example, a non-metallic material such as a resin, rubber, or a
fiber-reinforced resin may be used as the material of the cap
94.
[0137] The head 91 of the rod 90 may be provided with a hexagonal
groove, for example. The male thread 92 of the rod 90 can be
screwed into the female thread 224 of the connector 223 by
inserting the tip of a hex wrench or the like into the groove of
the head 91 of the rod 90 and causing the rod 90 to rotate. The rod
90 is screwed into the connector 223 such that the rod 90 extends
from the recessed portion 222 toward the back surface of the face
10, and the cap 94 contacts the back surface of the face 10.
[0138] That is, when the rod 90 is attached to the connector 223,
the cylindrical portion 93, which is a metallic member, indirectly
contacts the back surface of the face 10 via the cap 94, which is a
non-metallic member. In other words, the total length of the rod 90
and the position of the connector 223 are designed such that the
cap 94 at the tip side of the rod 90 contacts the back surface of
the face 10.
[0139] The rod may be configured as illustrated in FIG. 22. FIG. 22
is a cross-sectional view (part 2) of the golf club head 1E
according to the sixth embodiment. In FIG. 22, a rod 90A is
attached to the connector 223. The rod 90A illustrated in FIG. 22
is attachable to and detachable from the connector 223. The rod 90A
differs from the rod 90 in that the rod 90A does not include the
cap 94. In addition, because the cap 94 is not included, the tip
side of the cylindrical portion 93 is not reduced in diameter.
[0140] In FIG. 22, when the rod 90A is attached to the connector
223, the tip of the cylindrical portion 93 of the rod 90A contacts
the back surface of the face 10. In other words, the total length
of the rod 90A and the position of the connector 223 are designed
such that the tip of the cylindrical portion 93 of the rod 90A
contacts the back surface of the face 10.
[0141] As described above, the tip of the rod 90 or the rod 90A
contacts the back surface of the face 10, thereby restricting the
deformation of a contact portion between the face 10 and the rod 90
or the rod 90A. That is, the rod 90 and the rod 90A each function
as a reinforcing member that restricts the local deformation of the
face 10. The tip of the rod 90 or the rod 90A is tapered so as to
make point contact with the back surface of the face 10, thus
preventing the deformation of the face 10 from being excessively
restricted.
[0142] The tip of the rod 90 or the rod 90A may contact the back
surface of the face 10 so as not to press the back surface of the
face 10 in a natural state, or may contact the back surface of the
face 10 so as to press the back surface of the face 10 toward the
face surface 10f side. In addition, the degree of pressing the back
surface of the face 10 may be adjusted in accordance with the
degree of tightening of the male thread 92 to the connector 223. If
the male thread 92 is tightened to the maximum extent, the distal
end of the rod 90 or the rod 90A may slightly displace the back
surface of the face 10 toward the face surface 10f side.
[0143] With regard to the rigidity distribution of the face 10,
restricting the deformation of the contact portion between the face
10 and the rod 90 or the rod 90A causes the rigidity from the
center portion to the upper portion of the face 10 to be relatively
low and causes the rigidity of the lower portion of the face 10 to
be relatively high. That is, the upper portion of the face 10
readily deflects toward the back side by the impact of a golf ball.
Accordingly, the launch angle of the golf ball can be further
increased.
[0144] Further, the weight of the rod 90 or the rod 90A causes the
center of gravity of the golf club head if to be located on the
face 10 side. Accordingly, the amount of backspin of a golf ball
tends to be reduced, and thus the maximum flight distance of the
golf ball can be increased. That is, the rod 90 or the rod 90A may
also function as a threaded weight member.
[0145] As described above, in the golf club head 1E, at least the
sole 22 of the body 20 is formed by laminating layers of a
fiber-reinforced resin. Therefore, the connector 223 made of metal
can be readily embedded into the sole 22. Further, the rod 90 or
the rod 90A is attached to the connector 223 such that the tip of
the rod 90 or the rod 90A contacts the back surface of the face 10,
thereby allowing the deformation of the face 10 to be restricted.
The upper limit of the resilience of the face 10 is defined by the
official rules of golf. However, by causing the tip of the rod 90
or the rod 90A to contact the back surface of the face 10 such that
the deformation of the face 10 is restricted, the resilience of the
face 10 can be intentionally reduced. As a result, the golf club
head 1C can be designed to have a higher resilience over a wider
range than conventional designs.
[0146] Further, as described above, the rod 90 or the rod 90A is
attached to the connector 223 such that the tip of the rod 90 or
the rod 90A contacts the back surface of the face 10, thereby
allowing the deformation of the face 10 to be restricted.
Accordingly, the upper portion of the face 10 readily deflects
toward the back side by the impact of a golf ball, and thus the
launch angle of the golf ball can be further increased. Further, if
the crown 21 is formed by laminating layers of a fiber-reinforced
resin, the crown 21 is more readily deflected, and as a result, an
initial velocity can be increased as compared to the related
art.
[0147] In the above, an example in which the rod 90 or the rod 90A
is attached to the connector 223 has been described. However,
instead of the rod 90 or the rod 90A, a threaded weight member that
is exposed to the outside of the golf club head 1E may be attached
to the connector 223. Similar to the rods 90 and 90A, the weight
member can be configured to include a male thread; however, the tip
of the weight member does not necessarily contact the face.
Further, a plurality of weight members having different weights may
be prepared, and the position of the center of gravity of the golf
club head 1F can be adjusted by varying a weight member attached to
the connector 223. Further, a plurality of connectors may be
provided in the sole 22, and two or more weight members may be
attached to the connectors.
[0148] Accordingly, in the golf club head 1E, the crown 21, the
sole 22, and the hosel chamber 23 are formed by laminating layers
of a fiber-reinforced resin, thus allowing additional weight to be
readily secured as compared to conventional golf club heads. As a
result, the additional weight can be added to a rod or a weight
member.
Seventh Embodiment
[0149] A seventh embodiment depicts a golf club head in which the
rigidity of the crown and the rigidity of the sole are controlled.
In the seventh embodiment, descriptions of elements identical to
those in the above-described embodiment may be omitted.
[0150] FIG. 23 is a plan view of a golf club head 1F according to
the seventh embodiment. FIG. 24 is a partially enlarged view of the
golf club head 1F when viewed from the inner surface of the crown
21 according to the seventh embodiment. As illustrated in FIG. 23
and FIG. 24, in the golf club head 1F, at least the crown 21, the
sole 22, and the hosel chamber 23 of the body 20 are formed by
laminating layers of a fiber-reinforced resin. The crown 21
includes three thin slits 211.
[0151] The slits 211 may be recessed portions that are elongated to
partially extend in the toe-heel direction and are recessed from
the inner surface of the crown 21 toward the outer surface of the
crown 21. The slits 211 may be arranged at predetermined intervals.
The slits 211 serve as rigidity control portions that decrease the
flexural rigidity mainly in the face-back direction while reducing
the influence on the flexural rigidity in the toe-heel
direction.
[0152] Each of the slits 211 has a width W1, for example, greater
than or equal to 1.0 mm and less than or equal to 10.0 mm and
preferably greater than or equal to 2.0 mm and less than or equal
to 5.0 mm. The distance S1 between two adjacent slits 211 may be,
for example, greater than or equal to 1.0 mm and less than or equal
to 20.0 mm and preferably greater than or equal to 3.0 mm and less
than or equal to 8.0 mm. Each of the slits 211 may have a depth,
for example, greater than or equal to 0.1 mm and less than or equal
to 1.0 mm and preferably greater than or equal to 0.2 mm and less
than or equal to 0.4 mm. Each of the slits 211 may have a length
L1, for example, greater than or equal to 10.0 mm and less than or
equal to 120.0 mm and preferably greater than or equal to 40.0 mm
and less than or equal to 80.0 mm.
[0153] In FIG. 23, the three slits 211 are provided; however, this
is merely an example. At least one slit 211 may be provided, and
preferably, a plurality of slits 211 may be provided. Any number of
slits can be provided depending on the required rigidity. As the
number of slits 211 increases, the rigidity of the crown 21
decreases as long as the slits 211 have the same width, length, and
depth.
[0154] The crown 21 may be formed by laminating three layers of
prepregs as illustrated in FIG. 25 while heating and applying
pressure to the prepregs. However, the crown 21 may be formed by
laminating more than three layers of prepregs.
[0155] In FIG. 25, unidirectional (UD) prepregs in which
reinforcing fibers are unidirectionally oriented and impregnated
with a resin may be used as prepregs 51 and 53, which are located
at the top and the bottom of the crown 21. The fibers in the
prepregs 51 and 53 may be oriented approximately in the toe-heel
direction. However, UD prepregs in which fibers are oriented to be
inclined with respect to the toe-heel direction, or prepregs in
which reinforcing fibers are woven vertically and horizontally and
impregnated with a resin may also be used as the prepregs 51 and
53.
[0156] As the prepreg 52 sandwiched between the prepregs 51 and 53,
a UD prepreg in which reinforcing fibers are unidirectionally
oriented and impregnated with a resin may be used. The fibers in
the prepreg 52 are oriented approximately in the face-back
direction. The prepreg 52 is provided with three slits 521. When
the prepregs 51 through 53 are processed, the slits 521 function as
the slits 211.
[0157] As described above, the UD prepreg in which the fibers are
oriented approximately in the face-back direction is used as the
prepreg 52, and the slits 521 elongated to extend in the toe-heel
direction are formed in the prepreg 52. With this configuration,
the flexural rigidity mainly in the face-back direction can be
decreased while reducing the influence on the flexural rigidity in
the toe-heel direction.
[0158] FIG. 26 is a bottom view of the golf club head 1F according
to the seventh embodiment. FIG. 27 is a front view of the body of
the golf club head 1F according to the seventh embodiment. As
illustrated in FIG. 26 and FIG. 27, the sole 22 includes two ribs
221. The two ribs 221 may be formed of a fiber-reinforced resin and
arranged to intersect with each other when viewed in the crown-sole
direction. The ribs 221 may be formed of the same fiber-reinforced
resin as the sole 22. The ribs 221 serve as rigidity control
portions that increase the flexural rigidity in the face-back
direction. Carbon fibers of the fiber-reinforced resin constituting
the sole 22 are preferably oriented in directions approximately the
same as the extending directions of the ribs 221.
[0159] The two ribs 221 are projecting portions that are elongated
to extend from the back surface side of the face 10 toward the back
end 25 and inclined with respect to a plane P. The plane P is
perpendicular to a horizontal ground plane on which the golf club
head 15 rests at a predetermined lie angle and a predetermined loft
angle, and includes an axis that extends from the center of the
face 10 in a direction normal to the face 10. Viewing in the
crown-sole direction means viewing in a direction normal to the
horizontal ground plane on which the golf club head 15 rests at the
predetermined lie angle and the predetermined loft angle.
[0160] When viewed in the crown-sole direction, inclination angles
.theta.1 and .theta.2 of the two ribs 221 with respect to the plane
P may be, for example, greater than or equal to 15 degrees and less
than or equal to 45 degrees, and are preferably greater than or
equal to 25 degrees and less than or equal to 35 degrees.
[0161] When viewed in the crown-sole direction, an intersection C
of the two ribs 221 is preferably positioned so as to overlap with
the plane P. By positioning the two ribs 221 in this manner, the
rigidity of a part of the sole 22 can be readily increased.
[0162] Each of the ribs 221 has a width W2, for example, greater
than or equal to 0.5 mm and less than or equal to 3.0 mm and
preferably greater than or equal to 1.0 mm and less than or equal
to 2.0 mm. Each of the ribs 221 has a height, for example, greater
than or equal to 0.5 mm and less than or equal to 10 mm and
preferably greater than or equal to 2.0 mm and less than or equal
to 6.0 mm. Each of the ribs 221 has a length L2, for example,
greater than or equal to 30.0 mm and less than or equal to 120.0 mm
and preferably greater than or equal to 60.0 mm and less than or
equal to 80.0 mm.
[0163] In the examples of FIG. 26 and FIG. 27, two ribs 221 are
provided; however, this is merely an example. One or more ribs 221
may be provided depending on the required rigidity. For example, a
single rib 221 that extends in a straight line or a curved line in
any direction may be provided. If a plurality of ribs 221 are
provided, the plurality of ribs 221 do not necessarily intersect
with each other. For example, two or more ribs 221 may be arranged
in parallel approximately in the face-back direction, or may be
arranged in a V shape that opens toward the face side.
Alternatively, one or more ribs 221 that are approximately parallel
to the face-back direction and one or more ribs 221 that are
approximately perpendicular to the face-back direction may be
arranged to intersect with each other.
[0164] In order to form such a slit 211 and a rib 221, the slit may
be formed in a portion of prepregs and a portion of the prepregs
may be formed in a rib shape before the prepregs are laminated when
a golf club head is manufactured by the method described in the
first embodiment.
[0165] As described above, in the golf club head 1F, at least the
crown 21, the sole 22, and the hosel chamber 23 of the body 20 are
formed by laminating layers of a fiber-reinforced resin.
Accordingly, the rigidity of the crown 21 and the rigidity of the
sole 22 can be readily adjusted in contrast to when the crown 21
and the sole 22 are formed of a metal such as titanium. The ball
striking performance of the golf club head 1F is improved by
controlling the rigidity of the crown 21 and the rigidity of the
sole 22, which are formed of a fiber-reinforced resin.
Specifically, while the slits 211 decrease the flexural rigidity in
the face-back direction of the crown 21, the ribs 221 increase the
flexural rigidity in the face-back direction of the sole 22.
Accordingly, the crown 21 readily deflects by the impact of a golf
ball, and thus the launch angle of the golf ball can be
increased.
[0166] For a golf club head in which the body 20 is formed of a
metal such as titanium, there may be many limitations depending on
the manufacturing method (casting or forging). Particularly, if the
thickness of a predetermined portion is increased in order to
partially increase the flexural rigidity, the weight of the
predetermined portion would be increased. As a result, the degree
of freedom in designing functions of the head would be reduced.
Similarly, if the thickness of a predetermined portion is decreased
in order to partially decrease the flexural rigidity, the
structural strength of the head would be reduced. As a result, the
head would be susceptible to damage from impact when hitting a
ball. Therefore, it would not be easy to decrease the rigidity of a
crown 21 and increase the rigidity of a sole 22 while reducing the
influence on other elements. Thus, rigidity control would be
limited to a narrow range.
[0167] In contrast, in the above-described manufacturing method in
which a fiber-reinforced resin is used as the material of the body
20, prepregs including fibers having various elastic moduli may be
used, prepregs having different ratios of fibers to a resin may be
used, prepregs may be formed in various shapes, or prepregs may be
combined with a different material (such as a metal wire, metal
mesh, or a blowing agent). Accordingly, rigidity can be designed in
a wider range, not achievable if the body 20 were formed of a metal
such as titanium. As a result, golf clubs with suitable
characteristics can be provided to golfers with different swing
types.
[0168] In the present embodiment, the slits 211 are adopted as
rigidity control portions that decrease the flexural rigidity
mainly in the face-back direction while reducing the influence on
the flexural rigidity in the toe-heel direction, and the ribs 221
are adopted as rigidity control portions that increase the flexural
rigidity in the face-back direction. However, the present invention
is not limited thereto, and the slits 211 are not necessarily
formed. For example, instead of the slits 211, a low elasticity
material may be provided, or a prepreg sheet cut in a rectangular
shape and having slit-like openings may be provided. Further, metal
wires or metal mesh may be adopted instead of the ribs 221.
Alternatively, the ribs 221 may be metal pieces, or may be metal
pieces covered by a fiber-reinforced resin. Examples of low
elasticity materials include resins, rubber, and fiber-reinforced
resins.
[0169] In the present embodiment, the rigidity control portions
that decrease the flexural rigidity mainly in the face-back
direction while reducing the influence on the flexural rigidity in
the toe-heel direction are provided in the crown 21, and the
rigidity control portions that increase the flexural rigidity in
the face-back direction are provided in the sole 22. However, the
present invention is not limited thereto, and rigidity control
portions that increase the flexural rigidity mainly in the
face-back direction while reducing the influence on the flexural
rigidity in the toe-heel direction may be provided in the crown 21,
and rigidity control portions that decrease the flexural rigidity
mainly in the face-back direction while reducing the influence on
the flexural rigidity in the toe-heel direction may be provided in
the sole 22. In this case, the effect for preventing a ball from
being hit too high can be provided.
[0170] The seventh embodiment can be implemented simultaneously
with any other modifications. For example, the golf club head 1F
may be provided with a metal hosel and a rod.
Eighth Embodiment
[0171] An eighth embodiment depicts examples of golf club heads
each including a body having a different configuration. In the
eighth embodiment, descriptions of elements identical to those in
the above-described embodiments may be omitted.
[0172] FIG. 28 is an exploded perspective view of a golf club head
1G according to the eighth embodiment. As illustrated in FIG. 28,
the golf club head 1G has a hollow structure in which the face 10
is integrated with a body 30.
[0173] The body 30 includes a first member 31 located on the crown
side and a second member 32 located on the sole side. The first
member 31 and the second member 32 are combined to form the body
30, and the body 30 and the face 10 are further combined to form
the golf club head 1G.
[0174] For example, the golf club head 1G is manufactured by the
method as described below. First, a mold assembly, constituted by
an upper mold and a lower mold that can be assembled and
disassembled, is prepared. A plurality of layers of prepregs formed
of a fiber-reinforced resin are prepared, and the prepregs are
attached to the upper mold so as to be laminated. In this manner,
the first member 31 is formed. Next, a plurality of layers of
prepregs formed of a fiber-reinforced resin are prepared, and the
prepregs are attached to the lower mold so as to be laminated. In
this manner, the second member 32 is formed.
[0175] Next, the upper mold and the lower mold are assembled such
that the first member 31 is coupled to the second member 32. In
this manner, a blank of the body 30 of the golf club head 1G is
formed.
[0176] Next, the mold assembly including the blank of the body 30
is placed into a bag. The bag is placed in an openable sealed
container, and heat is applied by the heating mechanism while a
vacuum is created by the pneumatic mechanism. In this manner, the
prepregs formed of the fiber-reinforced resin, which constitute the
blank of the body 30, are cured by a cross-linking reaction. After
the heating, the body 30 is bonded to the preformed face 10 to form
a semi-finished golf club head. The semi-finished golf club head is
deburred and subjected to surface finishing to obtain the golf club
head 1G.
[0177] FIG. 29 is an exploded perspective view of a golf club head
1H according to the eighth embodiment. As illustrated in FIG. 29,
the golf club head 1H has a hollow structure in which the face 10
is integrated with a body 40.
[0178] The body 40 includes a first member 41 located on the face
side and a second member 42 located on the back side. The first
member 41 and the second member 42 are combined to form the body
40, and the body 40 and the face 10 are further combined to form
the golf club head 1H.
[0179] For example, the golf club head 1H may be manufactured by a
method as described below. First, a mold assembly, constituted by a
front mold and a back mold that can be assembled and disassembled,
is prepared. A plurality of layers of prepregs, formed of a
fiber-reinforced resin, are prepared, and the prepregs are attached
to the front mold so as to be laminated. In this manner, the first
member 41 is formed. Next, a plurality of layers of prepregs formed
of a fiber-reinforced resin are prepared, and the prepregs are
attached to the back mold so as to be laminated. In this manner,
the second member 42 is formed.
[0180] Next, the front mold and the back mold are assembled such
that the first member 41 and the second member 42 are coupled
together. In this manner, a blank of the body 40 of the golf club
head 1H is formed.
[0181] Next, the mold assembly including the blank of the body 40
is placed into a bag. The bag is placed in an openable sealed
container, and heat is applied by the heating mechanism while a
vacuum is created by the pneumatic mechanism. In this manner, the
prepregs formed of the fiber-reinforced resin, which constitute the
blank of the body 40, are cured by a cross-linking reaction. After
the heating, the body 40 is bonded to the preformed face 10 to form
a semi-finished golf club head. The semi-finished golf club head is
deburred and subjected to surface finishing to obtain the golf club
head 1H.
[0182] As described above, an integrally formed body may be used as
described in the golf club heads 1 to 1F, or a composite body may
be used as described in the golf club heads 1G and 1H.
[0183] According to an aspect of the present disclosure, a golf
club head at least partially formed of a fiber-reinforced resin can
be reduced in weight and increased in volume while also improving
ball striking performance.
[0184] Although the embodiments of the present invention have been
described in detail above, the present invention is not limited to
the particulars of the above-described embodiments. Variations and
modifications may be applied to the above-described embodiments
without departing from the scope of the present invention.
* * * * *