U.S. patent application number 09/897141 was filed with the patent office on 2002-02-14 for golf club head.
Invention is credited to Yabu, Masanori.
Application Number | 20020019266 09/897141 |
Document ID | / |
Family ID | 18698799 |
Filed Date | 2002-02-14 |
United States Patent
Application |
20020019266 |
Kind Code |
A1 |
Yabu, Masanori |
February 14, 2002 |
Golf club head
Abstract
A golf club head which comprises a face, a crown, a sole, a
sidewall extending from the periphery of the sole towards the crown
excluding the face, and a neck to be fixed to a shaft, and the head
is formed by welding together a face member for the face, a crown
member for the crown and a walled sole member for forming at least
the sole and the sidewall, wherein the walled sole member is made
by monoblock casting, and the face member and the crown member are
each made by plastic deformation processing.
Inventors: |
Yabu, Masanori; (Kobe-shi,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
18698799 |
Appl. No.: |
09/897141 |
Filed: |
July 3, 2001 |
Current U.S.
Class: |
473/345 |
Current CPC
Class: |
Y10T 29/4998 20150115;
A63B 53/0416 20200801; A63B 53/0466 20130101; B22C 9/04 20130101;
A63B 60/00 20151001; A63B 53/0437 20200801; A63B 53/0408 20200801;
A63B 53/0412 20200801 |
Class at
Publication: |
473/345 |
International
Class: |
A63B 053/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 3, 2000 |
JP |
2000-201038 |
Claims
1. A golf club head comprising a face for hitting a golf ball, a
crown, a sloe, a sidewall extending from the periphery of the sole
towards the crown excluding the face, and a neck to be fixed to a
shaft, and formed by welding together a face member for forming the
face, a crown member for forming the crown and a walled sole member
for forming at least the sole and the wall, the walled sole member
made by monoblock casting, and the face member and the crown member
each made by plastic deformation processing.
2. The golf club head according to clam 1, wherein the neck is
formed by the walled sole member whereby the sole, sidewall and
neck are formed as a monoblock casting.
3. The golf club head according to clam 1, wherein the neck is
formed by a neck member, and the neck member, face member, crown
member and walled sole member are welded together.
4. The golf club head according to clam 1, wherein the volume of
the head is not less than 250 cm.sup.3.
5. The golf club head according to clam 2, wherein the volume of
the head is not less than 250 cm.sup.3, and the face member, crown
member and walled sole member each have a specific gravity of not
more than 5.0.
6. The golf club head according to clam 3, wherein the volume of
the head is not less than 250 cm.sup.3, and the face member, crown
member, walled sole member and neck member each have a specific
gravity of not more than 5.0.
7. The golf club head according to any of the preceding clams,
wherein the monoblock casting is a lost-wax process.
8. The golf club head according to any of the preceding clams,
wherein the plastic deformation processing is a press forming of a
rolled sheet metal.
9. The golf club head according to clam 1, wherein the volume of
the head is not less than 300 cm.sup.3.
10. The golf club head according to clam 1, wherein a sweet spot
height is not more than 28.0 mm.
11. The golf club head according to clam 1, wherein a depth of the
center of gravity is not less than 36.0 mm.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a golf club head having a
structure being capable of increasing the degree of freedom of
design and the degree of freedom of selecting materials.
[0003] 2. Description of the Related Art including information
disclosed under 37 CFR 1.97-1.99
[0004] Conventionally, wood-shaped metallic golf club heads are
formed by welding metallic parts together. Such club heads are
disclosed in the following prior arts.
[0005] In U.S. Pat. No. 5,024,437 (Patent date: Jun. 18, 1991,
Filing date: Mar. 13, 1990), a golf club head having a two-piece
structure is disclosed, wherein the two pieces are a face plate and
a main body. The face plate is fabricated of forged carbon steel,
forged stainless steel, forged berylium copper or forged titanium.
The main body is formed by investment casting of stainless steel,
beryllium copper, titanium, aluminum or the like.
[0006] In Japanese patent No. 3135396 (Issue date: Dec. 1, 2000,
Laid-open date: Jun. 21, 1994, Filing date: Dec. 4, 1992), a golf
club head having a two-piece structure is disclosed. In this case,
the head is hollow, and the two pieces are a face plate and a main
body. The main body is formed by casting of a titanium alloy. The
face plate is fabricated of rolled or forged titanium alloy which
is different from the titanium alloy of the main body.
[0007] In the laid-open Japanese patent application JP-A-3-51065
(Laid-open date: Mar. 5, 1991, Filing date: Jul. 19, 1989), a golf
club head having a two-piece structure is disclosed. In this case,
the head is also hollow, and the two pieces are a bottom-opened
main body and a sole plate closing the bottom. The main body is
formed by casting of titanium or a titanium alloy. The sole plate
is fabricated of pressed titanium or a pressed titanium alloy.
[0008] In general, castings have a tendency to decrease the
strength sharply when the thickness is decreased beyond a certain
value due to crystal structure and material imperfection such as
air holes. Thus, it is necessary to design the thickness somewhat
greater.
[0009] In the hollow club heads as in the later two prior arts,
therefore, it is difficult to decrease the thickness of the crown
for the purpose of lowering the center of gravity, and decrease the
thickness of the face for the purpose of improving the restitution
coefficient. Further, it is difficult to optimize the position of
the center of gravity, weight distribution, moment of inertia and
the like of the head. Thus, the freedom of designing the head is
considerably limited.
SUMMARY OF THE INVENTION
[0010] It is therefore, an object of the present invention to
provide a golf club head, in which the degree of design freedom is
increased, and the position of the center of gravity, moment of
inertia and the like of the club head can be optimized.
[0011] According to the present invention, a golf club head
comprises a face for hitting a golf ball, a crown, a sole, a
sidewall extending from the periphery of the sole towards the crown
excluding the face, and a neck to be fixed to a shaft, and the golf
club head is formed by welding together a face member for forming
the face, a crown member for forming the crown and a walled sole
member for forming at least the sole and the sidewall, wherein the
walled sole member is made by casting, and the face member and the
crown member are each made by plastic deformation processing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a golf club head according
to the present invention.
[0013] FIG. 2 is a cross sectional view thereof.
[0014] FIG. 3 is an exploded view of the head showing a four-piece
structure.
[0015] FIG. 4 is an exploded view of the head showing a three-piece
structure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] Embodiments of the present invention will now be described
in detail in conjunction with the accompanying drawings.
[0017] In the drawings, golf club head 1 according to the present
invention is a wood-shaped metallic head for a metal wood club.
[0018] As shown in FIG. 1, the golf club head 1 is hollow and has a
face 2 for hitting a golf ball, a crown 3 defining an upper face of
the head intersecting the face 2 along the upper edge 2a of the
face 2, a sole 4 defining a bottom face of the head intersecting
the face 2 along the lower edge 2b of the face 2, a sidewall 5
between the crown 3 and sole 4 extending between the toe side edge
and heel side edge of the face 2 through the back of the head, and
a neck 6 to be fixed to a shaft (not shown).
[0019] In FIG. 3 showing a first embodiment, the golf club head 1
has a four-piece structure comprising a planar face member 12 for
forming the face 2, a slightly curved crown member 13 for forming
the crown 3, a neck member 16 for forming the neck 6, and a walled
sole member 17 which is composed of a sole part 14 for forming the
sole 4 and a sidewall part 15 for forming the sidewall 5, extending
upwards from the periphery 14e of the sole part 14 excluding the
face 2. These members 12, 13, 16 and 17 are welded together.
[0020] The walled sole member 17 is made by casting. In other
words, the sole part 14 and sidewall part 15 are formed as a
monoblock casting 20. Contrary, the face member 12 and crown member
13 are made by plastic deformation processing. In other words, each
of the face member 12 and crown member 13 is a plasticity processed
piece 21.
[0021] Here, the term "plastic deformation processing" means
various processing methods being made utilizing plastic deformation
to achieve the final shape of the part, inclusive of forging and
press forming. The forging includes "cold forging" at room
temperature, "warm forging" at an under recrystallization
temperature and "hot forging" at an over recrystallization
temperature, which may be made using a die, hammer, press or the
like. The press forming includes "bending" and "drawing" being made
utilizing a press. The processing temperature thereof is not
limited here.
[0022] As for the casting, on the other hand, it is also possible
to employ various methods, but "precision casting" is
preferable.
[0023] In this example, a "lost-wax precision casting" is employed
in making the above-mentioned walled sole member 17 to provide a
variable thickness distribution for the sole part 14 and the
sidewall part 15 in order to realize an optimum weight
distribution.
[0024] As for the material of the walled sole member 17, a titanium
alloy such as Ti-6Al-4V having a low specific gravity and high
strength may be preferably used.
[0025] The thickness ratio (t2/t1) between the minimum thickness t1
and maximum thickness t2 of the walled sole member 17 is set in a
range of from 1.2 to 3.0, preferably 1.5 to 2.5. For example, the
minimum thickness t1 and maximum thickness t2 of the walled sole
member 17 are 0.8 mm and 3.5 mm, respectively.
[0026] Because the walled sole member 17 which forms the major part
of the head is a monoblock casting, it is easy to change the
thickness in the sole part 14 and sidewall part 15. Accordingly, a
desired weight distribution can be obtained without using a
separate weighting member. This increases the degree of freedom of
designing the head especially the gravitational center and the
moment of inertia.
[0027] The face member 12 and crown member 13 in this example are
made as follow. A material for each member 12, 13 is punched out in
a specific shape (as shown in FIG. 3) from a rolled sheet metal
having a substantially uniform thickness. Then, the material is
bent by a press.
[0028] For example, the thickness of the face member 12 is in a
range of from 2.0 to 3.5 mm, preferably 2.0 to 3.0 mm. If the
thickness is less than 2.0 mm, the durability and strength thereof
are liable to become insufficient. If the thickness is more than
3.5 mm, the restitution coefficient is liable to decrease and the
weight distribution is liable to become not good.
[0029] The crown member 13 has a substantially constant thickness
of from 0.7 to 1.2 mm, preferably 0.7 to 0.9 mm. If the thickness
is less than 0.7 mm, the strength becomes insufficient. If the
thickness is more than 1.2 mm, the center of gravity of the head
becomes high and the golf club is liable to become difficult to
handle.
[0030] Because the face member 12 and crown member 13 are made by
plastic deformation processing, the degree of freedom of selecting
the metallic material increases when compared with casting. For
example, a titanium alloy Ti-15V-3Al-3Sn-3Cr whose tensile strength
is higher than Ti-6Al-4V, can be used although it is not suitable
for casting. In this example, such titanium alloy plate is used.
Therefore, the thickness of the face member 12 can be decreased to
the above-mentioned range without difficulty, thereby improving the
restitution coefficient.
[0031] The rolled sheet metal has a minute crystalline structure,
and its material imperfection such as air holes which are often
found in castings is very rare. Accordingly, the rolled sheet metal
has a high strength evenly. Therefore, the head can be decreased in
the thickness in the face 2 and crown 3, while maintaining a
sufficient strength. This also helps to reduce the weight of the
head. Further, due to the substantially constant thickness of the
face member 12 and crown member 13, accurate positioning of the
center of gravity becomes easy in designing the head.
[0032] In this embodiment, the above-mentioned neck member 16 is
made by forging. But it may be made by pressing, casting, cutting,
miling or the like.
[0033] FIG. 4 shows a golf club head 1 according to the present
invention which has a three-piece structure.
[0034] In this embodiment, the above-mentioned neck member 16 and
walled sole member 17 are formed as a monoblock casting
(hereinafter the "member 22").
[0035] Thus, the member 22 comprises a sole part 14 for forming the
sole 4, a sidewall part 15 for forming the sidewall 5, and a neck
part 16 forming the neck 6. Accordingly, the golf club head 1 is
composed of the member 22, a face member 12 and a crown member 13
which are welded together.
[0036] The face member 12 and crown member 13 have been described
in the former embodiment. Although the member 22 is made by
casting, the face member 12 and crown member 13 are made by plastic
deformation processing as explained above. The above description of
the walled sole member 17 may be applied to the member 22.
[0037] In this embodiment, as the sole part 14, sidewall part 15
and neck part 16 are formed as a monoblock casting, it is easy to
improve the accuracy of the neck 6 in respect of its dimension and
angle relative to the sole 4 when compared with the separate neck
member 16.
[0038] In both the embodiments shown in FIG. 3 and FIG. 4, the
assembly, namely, the head 1 has the following specifications.
[0039] The volume of the head 1 is set in a range of not less than
250 cm.sup.3, preferably not less than 280 cm.sup.3, more
preferably not less than 300 cm.sup.3.
[0040] The sweet spot height H is set in a range of not more than
28.0 mm.
[0041] The depth L of the center of gravity G is set in a range of
not less than 36.0 mm.
[0042] The lateral moment of inertia of the head is set in a range
of not less than 3500 cm.sup.4, and the vertical moment of inertia
is set in a range of not less than 2000 cm.sup.4.
[0043] Definition
[0044] Sweet spot: The sweet spot SS is defined as a point at which
a straight line N drawn normally to the face from the center of
gravity G intersects the face.
[0045] Standard state: A state that the head is set on a horizontal
plane satisfying its lie angle and loft angle.
[0046] Sweet spot height H: A vertical height measured from the
horizontal plane to the sweet spot SS in the standard state.
[0047] Depth L of the center of gravity: The horizontal distance
between the center of gravity G and the leading edge E of the head
measured in the standard state.
[0048] Moment of inertia: The lateral moment of inertia is the
moment of inertia around the vertical axis passing through the
center of gravity G in the standard state. The vertical moment of
inertia is the moment of inertia around a horizontal axis passing
through the center of gravity G in the toe-heel direction of the
head in the standard state. These moments were measured with
"Moment of Inertia Measuring Instrument MODEL NO. 005-002, INERTIA
DYNAMICS Inc."
[0049] As for the metallic material of each of the members 12, 13,
16, 17 and 22, it is preferable that the specific gravity thereof
is not more than 5.0. If the specific gravity is more than 5.0, due
to weight constraint, it is necessary to decrease the thickness of
the material, restricting the rigidity and strength, and
requirements for dimensional accuracy will be more strict. For
example, titanium alloys, pure titanium, aluminum alloys, magnesium
alloys and the like are preferably used. The members 12, 13, 16 and
17 may be of the same material. But, preferably, different
materials are used at least between the face member 12 and the
other member (17, 22)
[0050] Comparison Tests
[0051] Wood-shaped golf club heads having the same outward form
were made by way of test and tested as follows. The results are
shown in Table 1.
[0052] Restitution Coefficient Test
[0053] The restitution coefficient e was measured according to the
"Procedure for Measuring the Velocity Ratio of a Club Head for
Conformance to Rule 4-1e, Appendix II, Revision 2 (Feb. 8, 1999),
United States Golf Association." The distance between the face of
the club head and the launching device to produce a ball velocity
of 160+/-0.5 fps was 55 inches. The radius of the target circle on
the face was 5 mm. The golf balls used were "Titleist, PINNACLE
GOLD." In Table 1, "A" means the restitution coefficient e is not
less than 0.81. "B" means the restitution coefficient e is less
than 0.81.
[0054] Hook Angle Deviation Test
[0055] The hook angle of the face was measured, and the deviation
of the measured angle from the design angle was examined. In Table
1, "A" means good. "B" means not good.
1 TABLE 1 Ex.1 Ex.2 Ref.1 Ref.2 Ref.3 Head volume (cm.sup.3) 320
Head weight (g) 186 Making Head structure -- method Face member
press forming press forming casting press forming press forming and
2.8 mm thick 2.8 mm thick 3.0 mm thick 2.8 mm thick 2.8 mm thick
Material Ti-15V-3Al-3Sn-3Cr Ti-15V-3Al-3Sn-3Cr Ti-6AL-4V
Ti-15V-3Al-3Sn-3Cr Ti-15V-3Al-3Sn-3Cr Crown member press forming
press forming casting press forming casting 0.8 mm thick 0.8 mm
thick 0.9 mm thick 0.8 mm thick Ti-6AL-4V Ti-15V-3Al-3Sn-3Cr
Ti-15V-3Al-3Sn-3Cr Ti-6AL-4V Ti-15V-3Al-3Sn-3Cr thickness Sole part
casting casting casting press forming crown part 0.9 mm 1.2 to 2.0
mm thick 1.2 to 2.0 mm thick 1.2 to 2.0 mm thick 1.2 mm thick sole
part 1.2 to Wall part Ti-6AL-4V Ti-6AL-4V Ti-6AL-4V Ti-6AL-4V 2.0
mm Neck part forging press forming wall part 1.2 to (Outer diameter
= Pure Ti Pure Ti 2.0 mm 12 mm) Sweet spot height (mm) 28.0 27.9
28.7 29.0 28.4 Depth of Center of gravity (mm) 37.1 36.8 35.4 34.3
35.9 Lateral moment of inertia (cm.sup.4) 3540 3535 3512 3350 3446
ertical moment of inertia (cm.sup.4) 2060 2055 1946 1968 2035
Restitution coefficient A A B A A Hook angle deviation B A A B
A
[0056] In the club heads according to the invention, it was
possible to set the sweet spot lower and the center of gravity
deeper. It was also possible to set the moment of inertia larger.
As the sweet spot height becomes lower, the flying distance may be
increased because an excessive backspin is avoided.
[0057] As the center of gravity G becomes deeper, the sweet area
becomes broader, and a loss of the flying distance at the time of
miss shot can be minimized.
[0058] As the moment of inertia becomes larger, the head becomes
stable even when missed, and a loss of the flying distance can be
decreased.
* * * * *