U.S. patent application number 11/094355 was filed with the patent office on 2005-10-20 for golf club head.
This patent application is currently assigned to BRIDGESTONE SPORTS CO., LTD.. Invention is credited to Ezaki, Hiroshi, Imamoto, Yasunori.
Application Number | 20050233831 11/094355 |
Document ID | / |
Family ID | 35049027 |
Filed Date | 2005-10-20 |
United States Patent
Application |
20050233831 |
Kind Code |
A1 |
Ezaki, Hiroshi ; et
al. |
October 20, 2005 |
Golf club head
Abstract
A hollow golf club head having a face portion, a sole portion, a
side portion, a crown portion, and a hosel portion is configured
such that a principal portion of the crown portion is made of a
fiber-reinforced plastic (FRP body), and the remaining portions are
made of a metal (metal body). An opening is disposed in the face
portion, and a face plate made of an amorphous metal is fitted
therein, and fixedly attached thereto by means of caulking. The
remaining portions of the metal body are made of a crystalline
metal.
Inventors: |
Ezaki, Hiroshi; (Tokyo,
JP) ; Imamoto, Yasunori; (Kawasaki-shi, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
BRIDGESTONE SPORTS CO.,
LTD.
|
Family ID: |
35049027 |
Appl. No.: |
11/094355 |
Filed: |
March 31, 2005 |
Current U.S.
Class: |
473/342 ;
473/345; 473/349 |
Current CPC
Class: |
B29C 70/885 20130101;
A63B 53/0416 20200801; A63B 53/0458 20200801; A63B 53/0466
20130101; A63B 60/02 20151001; A63B 2209/02 20130101; A63B
2053/0491 20130101; A63B 53/0433 20200801 |
Class at
Publication: |
473/342 ;
473/345; 473/349 |
International
Class: |
A63B 053/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2004 |
JP |
P2004-104905 |
Claims
What is claimed is:
1. A golf club head of a hollow shell structure comprising: a face
portion; a sole portion; a side portion; a crown portion; and a
hosel portion, wherein a principal portion of the crown portion is
made of a fiber-reinforced plastic, at least the face portion and a
front edge portion of the crown portion continuous with the face
portion are made of a metal, and at least a center portion of the
face portion is made of an amorphous metal.
2. The golf club head according to claim 1, wherein all portions
made of a metal are made of an amorphous metal.
3. The golf club head according to claim 1, wherein a peripheral
edge portion of the face portion is made of a crystalline metal,
and a face plate made of an amorphous metal is fixedly attached to
the peripheral edge portion.
4. The golf club head according to claim 1, wherein a front edge
portion of the side portion and a front edge portion of the sole
portion are made of a metal continuous with the face portion, a
center portion of the sole portion in a toe-heel direction is made
of a metal continuous with the metal front edge portion of the sole
portion, and the metal portion at the center of the sole extends to
a rear portion of the golf club head.
5. The golf club head according to claim 1, wherein all portions
other than the principal portion of the crown portion are made of a
metal, portions other than the face portion are made of a
crystalline metal, and a peripheral edge portion of the face
portion is made of a crystalline metal, and a face plate made of an
amorphous metal is fixedly attached to the peripheral edge
portion.
6. The golf club head according to claim 3, wherein the face plate
made of an amorphous metal is fixedly attached to the peripheral
edge portion of the face portion made of a crystalline metal, by
means of caulking the peripheral edge portion of the face
portion.
7. The golf club head according to claim 1, wherein a thickness of
the face portion falls within a range of 1 to 4 mm.
8. The golf club head according to claim 4, wherein an average
value of a width of the metal front edge portion of the crown
portion and those of the metal front edge portion of the side
portion in a front-rear direction falls within a range of 2 to 20
mm.
9. The golf club head according to claim 1, wherein rigidity of the
crown portion made of the fiber-reinforced plastic in a front-rear
direction is rendered lower than that in a toe-heel direction.
10. The golf club head according to claim 1, wherein the
fiber-reinforced plastic is made of carbon fiber whose elastic
modulus falls within a range of 20.times.10.sup.3 to
30.times.10.sup.3 kg/mm.sup.2.
11. The golf club head according to claim 1, wherein a thickness of
the crown portion made of the fiber-reinforced plastic falls within
a range of 1 to 2 mm.
12. The golf club head according to claim 1, wherein a volume of
the golf club head falls within a range of 350 to 400 cm.sup.3, and
a weight of the golf club head falls within a range of 160 to 200
g.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a hollow golf club head,
and particularly to a golf club head having a shape of a wood type
or a shape approximating the same.
[0003] 2. Description of the Related Art
[0004] A metal golf club head of a hollow structure has come into
wide use as a wood-type golf club head, such as a driver or a
fairway wood. Generally, a hollow wood-type golf club head has a
face portion for hitting a ball; a crown portion forming the upper
surface of the golf club head; a sole portion forming the lower
surface of the golf club head; a side portion forming side faces on
its toe, rear, and heel sides; and a hosel portion. A shaft is
inserted into the hosel portion, and fixed by means of an adhesive,
or the like. Recently, a number of golf clubs called utility clubs
are commercially available. A variety of golf clubs having heads
analogous to the above-mentioned wood-type golf club head (that is,
having a face portion, a sole portion, a side portion, a crown
portion and a hosel portion) are also commercially available as a
type of such utility golf clubs.
[0005] As a metal forming the hollow golf club head, an aluminum
alloy, stainless steel, or a titanium alloy has been used. Among
them, a titanium alloy in particular has been in wide use in recent
years.
[0006] When a hollow golf club head is increased in volume, the
sweet spot thereof can be expanded. In order to prevent the
increase in volume from leading to an increase in the weight of the
golf club head, consideration has been given to employing as the
constituent material of the golf club head a fiber-reinforced
plastic whose specific gravity is lower than those of the
above-listed metals. In this case, since the surface of the face
for hitting a ball must be made of a metal in order to ensure
strength, portions other than the face are made of a
fiber-reinforced plastic.
[0007] JP-A-2004-16654 discloses a golf club head wherein a face
portion, a front portion of a golf club head continuous with the
face portion, and a center portion in a width direction of a sole
portion are made of metals, and the remaining portions are made of
a CFRP.
SUMMARY OF THE INVENTION
[0008] JP-A-2004-16654 includes no description about use of an
amorphous metal as the metal.
[0009] The present invention aims at increasing coefficient of
restitution of the metal face portion of a golf club head whose
crown portion is made of a fiber-reinforced plastic, thereby
providing a golf club head which can increase a carry distance of a
golf ball.
[0010] According to an embodiment of the invention, there is
provided a hollow golf club head having a face portion, a sole
portion, a side portion, a crown portion and a hosel portion,
wherein a principal portion of the crown portion is made of a
fiber-reinforced plastic; at least the face portion and a front
edge portion of the crown portion continuous with the face portion
are made of a metal; and the portion of the crown portion made of
the fiber-reinforced plastic is affixed to a rear end surface and
an inner surface of the front edge portion, which is made of a
metal, of the crown portion.
[0011] Preferably, all portions made of a metal are made of an
amorphous metal.
[0012] Preferably, a peripheral edge portion of the face portion is
made of a crystalline metal, and a face plate made of an amorphous
metal is fixedly attached to the peripheral edge portion.
[0013] Preferably, a front edge portion of the side portion and a
front edge portion of the sole portion are made of a metal
continuous with the face portion; a center portion of the sole
portion in a toe-sole direction is made of a metal continuous from
the metal front edge portion of the sole portion; and the metal
portion at the center of the sole portion extends to a rear portion
of the golf club head.
[0014] Preferably, all portions other than the principal portion of
the crown portion are made of a metal; portions other than the face
portion are made of a crystalline metal; a peripheral edge portion
of the face portion is made of a crystalline metal; and a face
plate made of an amorphous metal is fixedly attached to the
peripheral edge portion.
[0015] Preferably, the face plate made of an amorphous metal is
fixedly attached to the peripheral edge portion of the face made of
a crystalline metal, by means of caulking the peripheral edge
portion side of the face.
[0016] The golf club head according to the embodiment of the
present invention is configured such that the main portion of the
crown portion is made of a fiber-reinforced plastic. Accordingly,
the crown portion is easily deformed upon hitting of a ball,
thereby exhibiting a favorable restitution property. In addition,
the golf club head can be reduced in weight.
[0017] In the configuration of the invention, at least the center
portion of the face portion is made of an amorphous metal. Since
the amorphous metal is higher in strength and lower in elasticity
than a crystalline metal, when the face portion is reduced in
thickness so as to increase the degree of deformation thereof upon
hitting of a ball, restitution is increased, whereby a carry
distance of a golf ball can be increased.
[0018] Meanwhile, unlike a crystalline metal, an amorphous metal is
difficult to process by means of forging, presswork, or welding. To
this end, when all the portions made of a metal are made of an
amorphous metal and integrally welded, manufacturing can be
facilitated. In addition, the following configuration may also be
alternatively employed. Namely, a peripheral edge portion of the
face portion is made of a crystalline metal, portions other than
the peripheral edge portion of the face portion are formed into a
face plate made of an amorphous metal, and the face plate is
fixedly attached to the peripheral edge portion by means of
caulking, or the like.
BRIEF DESCRIPTION OF THE DRAWING
[0019] These and other objects and advantages of this invention
will become more fully apparent from the following detailed
description taken with the accompanying drawings in which:
[0020] FIG. 1 is a perspective view of a golf club head according
to an embodiment of the invention;
[0021] FIG. 2 is a perspective view of a metal body of the golf
club head of FIG. 1, as viewed from the front;
[0022] FIG. 3 is a perspective view of the metal body of the golf
club head of FIG. 1, as viewed from the rear;
[0023] FIG. 4 is a side view of the metal body of the golf club
head of FIG. 1, as viewed from the heel side;
[0024] FIG. 5 is a plan view of the metal body of the golf club
head of FIG. 1;
[0025] FIG. 6A is a longitudinal cross-sectional view of the golf
club head of FIG. 1, taken along a line in the front-rear
direction, and FIG. 6B is an enlarged view of a portion of FIG.
6A;
[0026] FIGS. 7A and 7B are longitudinal cross-sectional views of a
rear portion of a golf club head according to another embodiment of
the invention, wherein FIG. 7A shows the state before attachment of
a plug-like member, and FIG. 7B shows the state after attachment of
the same;
[0027] FIG. 8 is a exploded perspective view of a metal body for
use in another embodiment;
[0028] FIGS. 9A and 9B are cross-sectional views showing an
attachment structure of a face plate of the metal body of FIG.
8;
[0029] FIG. 10 is a exploded perspective view of a metal body for
use in yet another embodiment; and
[0030] FIG. 11 is a cross-sectional view of a golf club head
provided with the metal body of FIG. 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Hereinafter, an embodiment of the invention will be
described by reference to the drawings. FIG. 1 is a perspective
view of a golf club head according to the embodiment of the
invention. FIG. 2 is a perspective view of a metal body of the golf
club head, as viewed from the front. FIG. 3 is a perspective view
of the metal body, as viewed from the rear. FIG. 4 is a side view
of the metal body, as viewed from the heel side thereof. FIG. 5 is
a plan view of the metal body. FIG. 6A is a longitudinal
cross-sectional view of the golf club head taken along a line in
the front-rear direction. FIG. 6B is an enlarged view of a portion
of FIG. 6A.
[0032] A golf club head 1 is a wood-type hollow golf club head
having a face portion 2, a sole portion 3, a side portion 4, a
crown portion 5, and a hosel portion 6. The golf club head 1 is
configured with a metal body 10 wholly made of an amorphous metal,
and a fiber-reinforced plastic body (hereinafter referred to as
"FRP body") 20.
[0033] As an alloy composition constituting the amorphous metal, a
zirconium amorphous alloy is preferable, and a zirconium amorphous
alloy represented by a general formula ZrMX is particularly
preferable, where M is one or more metal elements selected from V,
Cr, Mn, Fe, Co, Ni, Cu, Ti, Mo, W, Ca, Li, Mg, Si, Al, Pd and Be,
and X is one or more metal elements selected from Y, La, Ce, Sm,
Md, Hf, Nb and Ta. Meanwhile, the amorphous metal may be a
completely amorphous metal, or a semi-amorphous metal which
partially includes crystalline metal.
[0034] The metal body 10 includes the face portion 2, a metal sole
portion 13, a metal side portion (toe) 14, a metal crown portion
15, a metal side portion (heel) 16, a metal back portion 17, an
annular portion 18 disposed in the metal back portion 17, and the
hosel portion 6.
[0035] The face portion 2 is a face for hitting a ball, and
unillustrated grooves (score lines) are disposed thereon. The sole
portion 3 forms the lower surface of the golf club head. The side
portion 4 forms the side faces on the toe, heel, and rear-face
sides. The crown portion 5 forms the upper surface of the golf club
head. A shaft is inserted into the hosel portion 6 and fixedly
attached thereto by means of an adhesive.
[0036] The metal body 10 forms the face portion 2, the front edge
portion of the crown portion 5, the front edge portion of the side
portion 4, the front edge portion of the sole portion 3, the center
portion of the same in the lateral direction (in the heel-toe
direction), and the rear face portion of the golf club head.
[0037] The metal crown portion 15 forming the front edge portion of
the crown portion 5 is continuous with the metal side portion (toe)
14 and with the metal side portion (heel) 16. The metal side
portion (toe) 14 and the metal side portion (heel) 16 are
respectively continuous with the metal sole portion 13. The metal
side portions 14, 16 and the metal sole portion 13 are continuous
with the face portion 2.
[0038] The front portion of the metal sole portion 13 extends
across the golf club head from the toe side to the heel side
thereof. The metal sole 13 is gradually decreased in width rearward
from the front portion. The rear portion of the metal sole portion
13 is disposed at the center portion of the golf club head in the
heel-toe direction. The metal back portion 17 is continuous with
the rear end of the metal sole portion 13. The metal back portion
17 rises obliquely backward from the metal sole portion 13. The
annular portion 18 is formed integrally with the inner surface of
the metal back portion 17. An opening is provided through the
annular portion 18 and the metal back portion 17. A female thread
(not shown) is provided on the inner peripheral face of the
opening.
[0039] The amorphous metal body 10 can be manufactured by means of
casting a molten alloy into a die, followed by cooling at a
designated cooling rate or faster. The cooling rate is determined
in consideration of the amorphous metal composition.
[0040] The FRP body 20 forms the remaining portions of the external
surface of the golf club head 1. More specifically, the FRP body 20
forms a rear half portion of the crown portion 5, a rear half
portion (excluding the metal back portion) of the side portion 4,
and portions of the sole portion 3 other than the metal sole
portion 13.
[0041] The FRP body 20 is shown in enlarged view in FIG. 6, and is
in close contact with the end surfaces of the metal crown portion
15, the metal side portions (both toe and heel) 14 and 16, and the
metal sole portion 13. The FRP body 20 is also in close contact
with the inner surfaces of the edges of the same in an overlapping
manner. Particularly, in the metal crown portion 15, the FRP body
20 reaches the back surface of the face portion 2 as shown in FIG.
6B. More specifically, the FRP body 20 is in close contact with the
entire inner surface of the metal crown portion 15 in an
overlapping manner.
[0042] In order to form the FRP body 20 and integrally join the
same with the metal body 10, the metal body 10, whose inner surface
has been subjected to primer treatment as required, is placed in a
die whose inner shape is identical with an outer shape of the golf
club head. Subsequently, laminated prepreg sheets (an uncured
resin-fiber composite material sheet) are disposed along the inner
surface of the die and the inner surface of the edge of the metal
body 10. Meanwhile, the laminate may be pre-formed in advance so as
to fit along the inner surface of the die. Thereafter, the resin is
heated in a state where gas pressure is applied to the inside of
the die through the opening of the annular portion 18, to thereby
be cured. In relation to the above, the following method may
alternatively be adopted. That is, a resin bag of nylon or the like
is disposed inside the golf club head in advance. Gas is supplied
into the bag to thus inflate the bag, thereby pressing the prepreg
sheet so as to bring the prepreg sheet into close contact with the
inner surface of the die.
[0043] Accordingly, the FRP body 20 is formed; and simultaneously,
the peripheral edge portion 21 of the FRP body 20 is brought into
close contact with the end surface and the edge portion of the
metal body 10, as shown in FIG. 6. After completion of the molding,
the golf club head is released from the die, and a vibration
absorption layer and/or a ball-hitting sound adjustment layer is
formed on the inner surface of the golf club head as required. For
instance, by means of forming into the shape of a layer a
pressure-sensitive adhesive composed of polyisobutylene, or the
like, the golf club head can be prevented from generating an empty
sound.
[0044] A plug-like member 30 (not shown in FIGS. 1 to 6) is screwed
into the opening of the metal back portion 17. The female thread
for this screwing may be provided in the metal body 10 in advance
or after release from the die. Thereafter, the external surface of
the golf club head is subjected to grinding and painting as
required, thereby obtaining a golf club head product.
[0045] The plug-like member is preferably made of a material having
a high specific gravity, such as tungsten, so as to bring the
center of the gravity of the golf club head to a deeper
position.
[0046] Meanwhile, the plug-like member 30 may be fixedly attached
into an opening 40 of the annular portion 18 by means of brazing,
adherence, interference fit, or the like, as shown in FIG. 7. The
plug-like member 30 has a columnar portion 31, and a flange portion
32 provided at the rear end of the columnar portion 31. The opening
40 of the annular portion 18 has a step portion 41 in an entrance
portion of the opening 40. The flange portion 32 is engaged with
the step portion 41.
[0047] As the plug-like member 30, a tungsten-nickel-iron
(W--Ni--Fe) alloy having a high specific gravity of about 10 to 12
can be used. A suitable composition of the alloy is as follows:
[0048] W: 28 to 32 wt %;
[0049] Fe: 45 to 49 wt %;
[0050] Ni: 15 to 17 wt %; and
[0051] Cu: 1 to 2 wt %.
[0052] An alloy of the above composition can be subjected to
casting. The alloy of the composition is rich in Fe, and superior
in weldability with metals containing components such as stainless
steel and iron. Therefore, the alloy can be welded easily even by
TIG welding, a general welding method.
[0053] The club head configured as above, the metal body 10
including the face portion 2 thereof is made of an amorphous metal.
Accordingly, when the face portion 2 is reduced in thickness so as
to increase the degree of deformation thereof upon hitting of a
ball, restitution is increased, whereby a carry distance of a golf
ball can be increased. Meanwhile, thickness of the face portion 2
(excluding the peripheral edge portion) is suitably about 1 to 4
mm, particularly suitably about 1.5 to 3 mm. The peripheral edge
portion of the face portion 2 may be thicker than this. Since a
rear half of the golf club head is mainly made of the FRP body, the
golf club head is lightweight and can be increased in size.
[0054] In addition, the FRP body 20 is affixed also to the inner
surface of the edge of the metal body 10 in an overlapping manner.
Accordingly, bonding between the metal body 10 and the FRP 20 is
firm, and exhibits excellent durability. Meanwhile, the average
value of the width of the metal crown portion 15 and those of the
metal side portions 14, 16 in the front-rear direction (i.e., the
face-back direction) is preferably about 2 to 20 mm, particularly
preferably about 5 to 18 mm.
[0055] The golf club head according to the embodiment, the metal
sole portion 13, the metal side portions 14, 16, and the metal
crown portion 15 are disposed all around the circumference of the
face portion 2. Accordingly, the peripheral edge portion of the
face portion 2 has high rigidity. Therefore, even when the face
portion 2 is reduced in thickness, the metal body 10 as a whole is
provided with a required strength.
[0056] In the golf club head, the front edge portion of the sole
portion 3 is formed from the metal sole portion 13. Accordingly,
even when the front edge portion of the sole portion 3 hits the
ground (in a so-called "sclaffing") during the course of a swing,
the front edge portion of the sole portion 13 is not damaged.
[0057] In the golf club head, the metal sole portion 13 extends in
the front-rear direction at the center of the sole portion 3.
Accordingly, the center of gravity of the golf club head can be
lowered, whereby a ball can be hit high. In addition, since the
metal sole portion 13 extends rearward, the center of gravity of
the golf club head is brought to a deeper position, thereby
expanding the sweet spot. In addition, the annular portion 18 is
disposed in the metal back portion 17, which is continuous with the
metal sole portion 13 at the rearmost end thereof, and the
plug-like member made of a high specific gravity material is
fixedly attached to the annular portion 18. Accordingly, the center
of gravity is brought to a further deeper position.
[0058] In the embodiment, a portion of the hosel portion 6 is
disposed inside the golf club head as shown in FIG. 3. Accordingly,
the center of gravity can be lowered.
[0059] In addition, when the portion of the hosel portion 6 is
disposed inside the golf club head as described above, torsional
moment applied to the shaft at the time of hitting a ball is
reduced, whereby side-to-side runout of the thus-hit ball is
suppressed. Meanwhile, by means of reducing the protrusion length
of the hosel 6 out of the external surface of the golf club head,
the external appearance of the golf club head also becomes
favorable.
[0060] The length of the portion of the hosel portion 6 protruding
into the golf club head is desirably 10 to 50 mm, particularly
desirably 20 to 50 mm, and further particularly desirably 35 to 45
mm.
[0061] In the embodiment, the entire metal body 10 is made of an
amorphous metal; however, a metal body configured as follows may
also be employed. That is, portions of the face portion other than
the peripheral edge portion are made of an amorphous metal; and
portions of the metal body other than the face portion, and the
peripheral edge portion of the face portion are made of a
crystalline metal. A metal body 50 shown in FIGS. 8 to 9, and a
metal body 70 shown in FIGS. 10 and 11 are respectively configured
as follows.
[0062] Similar to the metal body 10 shown in FIGS. 1 to 7, the
metal body 50 shown in FIGS. 8 to 9 includes a face portion 52, a
metal sole portion 53, a metal side portion (toe) 54, a metal crown
portion 55, a metal side portion (heel), a metal back portion 57,
an annular portion 58, and a hosel portion 56.
[0063] The metal crown portion 55 forming the front edge portion of
the crown portion is continuous with the metal side portion (toe)
54 and with the metal side portion (heel). The metal side portion
(toe) 54 and the metal side portion (heel) are respectively
continuous with the metal sole portion 53. The metal side portion
54 and the metal sole portion 53 are continuous with the face
portion 52.
[0064] The front portion of the metal sole portion 53 extends in
the overall width of the golf club head from the toe side to the
heel side thereof. The metal sole portion 53 is gradually decreased
in width from the front portion rearward. The rear portion of the
metal sole portion 53 is disposed at the center portion of the golf
club head in the heel-toe direction. The metal back portion 57 is
continuous with the rear end of the metal sole portion 53. The
metal back portion 57 rises obliquely rearward from the metal sole
portion 53.
[0065] The annular portion 58 is formed integrally with the inner
surface of the metal sole portion 53. An opening is provided to
penetrate the annular portion 58, and a female thread (not shown)
is provided in the inner circumferential surface of the opening.
The plug-like member 30 (not shown in FIGS. 8 to 9) is screwed into
the annular portion 58.
[0066] In the metal body 50, portions referred to above are made of
a crystalline metal. Examples of the crystalline metal include
lightweight metals such as titanium, a titanium alloy, and an
aluminum alloy.
[0067] In the metal body 50, an opening 60 is disposed so as to
leave the peripheral edge portion of the face portion 52. A face
plate 52f made of an amorphous metal is fitted in the opening 60,
and fixedly attached thereto. In the embodiment, a step portion 61
is disposed on the inner peripheral edge portion of the opening 60;
and on the front face of an element assembly of the metal body 50
before attachment of the face plate 52f, a flange portion 62 is
provided along a circumference of an edge portion of the opening
60. A recessed step portion 63 is provided circumferentially along
the peripheral edge portion on the front-face side of the face
plate 52f in a surrounding manner. The face plate 52f is fitted to
the opening 60 so as to contact the step portion 61. Thereafter,
the flange portion 62 is caulked to thus crimp the recessed step
portion 63. Consequently, the face plate 52f is fixedly attached to
the peripheral edge portion of the face portion 52.
[0068] As a result of being substantially tabular, the face plate
52f can be manufactured easily even when made of an amorphous
metal. As a result of being made of a crystalline metal, the metal
body other than the face plate 52f can be manufactured easily by
means of any of a variety of methods, such as casting, forging,
press, cutting, and welding.
[0069] The metal body 50 shown in FIGS. 8 to 9 is configured by
means of disposing the opening 60 in the face the metal body 10
shown in FIGS. 1 to 7, and attaching the face plate 52f to the
opening 60. A golf club head including the metal body 50 is
analogous to the golf club head shown in FIGS. 1 to 7, except that
the metal body 10 is replaced with the metal body 50.
[0070] FIG. 10 is a perspective view of the metal body 70 wherein
the side portion and the back portion of a golf club head are also
made of a metal, and a face plate 72f made of an amorphous metal is
fixedly attached to the face portion. FIG. 11 is a cross-sectional
view taken along a front-rear longitudinal line of a golf club head
including the metal body 70.
[0071] The metal body 70 includes a face portion 72, a sole portion
73, a side portion (both toe and heel) 74, a metal crown portion
75, a back portion 77, and a hosel portion 76.
[0072] The metal crown portion 75 forms only the peripheral edge
portion of the crown portion of the golf club head. The remaining
portions of the crown portion other than the peripheral edge
portion form an opening 79, into which an FRP body 90 is
fitted.
[0073] In the face portion 72 of the metal body 70, an opening 80
is disposed so as to leave the peripheral edge portion of the face
portion 72; and the face plate 72f made of an amorphous metal is
fixedly attached in the opening 80. The metal body 70, not
including the faceplate 72f, is made of an crystalline metal.
Suitable examples of the crystalline metal include lightweight
metals such as titanium, a titanium alloy, and an aluminum alloy.
The opening 80, which has a configuration analogous to that of the
opening 60 of the metal body 50, is brought into contact with a
step portion 81, and the edge portion of the opening 80 is caulked.
Accordingly, the face plate 72f is fixedly attached to so as to
seal the opening 80.
[0074] The FRP body 90 is fixedly attached to the metal body 70 in
the same manner as in the FRP body 20 shown in FIGS. 1 to 7. In the
embodiment, the FRP body 90 is fixedly attached to the upper
surface of the metal crown portion 75 in an overlapping manner.
Although not illustrated, the metal body 70 may also be provided
with a plug-like member made of a high specific gravity
material.
[0075] A golf club head including the metal body 50 shown in FIGS.
8 to 9, or a golf club head including the metal body 70 shown in
FIGS. 10 and 11 is also provided with the metal face plate 52f,
72f, which is made of an amorphous metal in the face portion.
Accordingly, when the face portion is reduced in thickness so as to
increase the degree of deformation thereof upon hitting of a ball,
restitution is increased, whereby a carry distance of a golf ball
can be increased.
[0076] In the invention, by means of adjusting the orientation of
reinforcement fibers in the crown portion of the FRP body, rigidity
in the front-rear direction (face-back direction) may be rendered
lower than that in the toe-heel direction (lateral direction). When
such an adjustment is effected, deformation of the crown portion
upon hitting a ball is increased, thereby increasing a launch angle
of a ball. As a result, a carry distance (flight distance) of the
hit ball increases.
[0077] As prepreg for forming the FRP body, either cross fiber
prepreg or unidirectional fiber prepreg may be used.
[0078] The prepreg is preferably used in the form of laminated
prepreg with 3 to 8 sheets.
[0079] As the fiber in the prepreg, carbon fiber or the like whose
elastic modulus is about 20.times.10.sup.3 to 30.times.10.sup.3
kg/mm.sup.2 is suitable; however, the fiber is not limited
thereto.
[0080] As described above, the elastic modulus of the crown portion
in the front-rear direction is preferably rendered lower than that
in the toe-heel direction by means of adjusting the orientation of
the fibers. For instance, cross fiber prepreg and unidirectional
fiber prepreg are laminated alternately, and the fiber orientation
of the unidirectional fiber prepreg is caused to align in a
direction parallel to the toe-heel direction.
[0081] As a resin for the FRP body, a thermosetting resin such as
an epoxy can be used. Meanwhile, a small amount of thermoplastic
resin may be mixed into the thermosetting resin, thereby enabling
an improvement in vibration-absorbing property.
[0082] The FRP body is preferably about 1 to 3 mm in thickness. In
particular, the crown portion is preferably about 1 to 2 mm,
particularly preferably about 1 to 1.5 mm; for instance, about 1.3
mm.
[0083] The invention is suitable in application to a large head of
a volume greater than or equal to 300 cm.sup.3, particularly
greater than or equal to 350 cm.sup.3; for instance, 350 to 400
cm.sup.3. Manufacture of a very large head having a volume of about
600 cm.sup.3 is technically feasible. The weight of the golf club
head is suitably about 160 to 200 g, particularly suitably about
180 to 190 g.
[0084] The foregoing description of preferred embodiments of the
invention has been presented for purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise form disclosed, and modifications and
variations are possible in light of the above teachings or may be
acquired from practice of the invention. The embodiments were
chosen and described in order to explain the principles of the
invention and its practical application to enable one skilled in
the art to utilize the invention in various embodiments and with
various modifications as are suited to the particular use
contemplated. It is intended that the scope of the invention be
defined by the claims appended hereto, and their equivalents.
* * * * *