U.S. patent application number 11/115235 was filed with the patent office on 2005-11-03 for golf club head.
This patent application is currently assigned to BRIDGESTONE SPORTS CO., LTD.. Invention is credited to Kubota, Makoto, Motoyoshi, Koki, Nishitani, Masafumi, Yamagishi, Hisashi.
Application Number | 20050245329 11/115235 |
Document ID | / |
Family ID | 34941061 |
Filed Date | 2005-11-03 |
United States Patent
Application |
20050245329 |
Kind Code |
A1 |
Nishitani, Masafumi ; et
al. |
November 3, 2005 |
Golf club head
Abstract
An iron-type golf club head has a face having a face surface of
a flat surface, and a hosel which is continuous with the face on
its heel side. A shaft insertion hole is disposed in the hosel. A
protrusion protruding rearward in the vicinity of the center in a
toe-heel direction is disposed. A material of the golf club head is
pure iron having a high purity of at least 99.995%, for instance, a
purity within a range of 99.995 to 99.9999%. The golf club head is
subjected to carburizing so that carbon diffuses to a range of
about 0.2 to 0.5 mm from the surface.
Inventors: |
Nishitani, Masafumi;
(Kawasaki-shi, JP) ; Yamagishi, Hisashi;
(Hanno-shi, JP) ; Kubota, Makoto; (Kawaguchi-shi,
JP) ; Motoyoshi, Koki; (Hanno-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: |
34941061 |
Appl. No.: |
11/115235 |
Filed: |
April 27, 2005 |
Current U.S.
Class: |
473/349 |
Current CPC
Class: |
A63B 53/047 20130101;
A63B 53/0462 20200801; A63B 53/0454 20200801; A63B 53/0416
20200801 |
Class at
Publication: |
473/349 |
International
Class: |
A63B 053/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2004 |
JP |
P2004-133374 |
Claims
What is claimed is:
1. A golf club head comprising: a face made of a iron material
which is carburized, wherein the iron material is pure iron.
2. The golf club head according to claim 1, wherein purity of the
pure iron is at least 99.8%.
3. The golf club head according to claim 1, wherein the golf club
head is an iron-type golf club head.
4. The golf club head according to claim 2, wherein the golf club
head is an iron-type golf club head.
5. The golf club head according to claim 3, wherein the iron-type
golf club head has a loft angle of 25.degree. or more.
6. The golf club head according to claim 4, wherein the iron-type
golf club head has a loft angle of 25.degree. or more.
7. The golf club head according to claim 3, wherein a thickness of
the face in a vicinity of a center of gravity of the face falls
within a range of 3.5 to 15 mm.
8. The golf club head according to claim 5, wherein a thickness of
the face in a vicinity of a center of gravity of the face falls
within a range of 3.5 to 15 mm.
9. The golf club head according to claim 7, wherein the face is of
smaller thickness on a toe side and on a heel side than in the
vicinity of the center of gravity of the face.
10. The golf club head according to claim 8, wherein the face is of
smaller thickness on a toe side and on a heel side than in the
vicinity of the center of gravity of the face.
11. The golf club head according to claim 1, wherein hardness of a
surface of the face falls within a range of HV 180 to 900.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a golf club head,
particularly to a golf club head whose face is made of an iron
material. More specifically, the invention relates to a golf club
head for use in an iron-type golf club.
[0003] 2. Description of the Related Art
[0004] As a material for an iron-type golf club head, a soft iron,
stainless steel, a cupper alloy, and the like, has been used. In
addition, an iron golf club head of a composite type whose
peripheral edge section is made of stainless steel, and to which a
face plate made of a titanium alloy is attached has come into
widespread use in recent years. Hereinbelow, an iron-type golf club
head is often referred to as an "iron head."
[0005] An iron head made of pure iron whose purity falls within a
range of 99.93 to 99.97% is disclosed in JP-A-63-229078. In lines 1
to 8, upper left column, page 3 of the specification, it is
disclosed that pure iron has great elongation and drawing ratio,
and is superior in malleability, accordingly, a contact area
between a golf ball and a face of the iron head made of pure iron
is expanded, and a contact time is elongated, thereby enhancing
directional stability of a hit ball.
[0006] Forming a surface hardening layer on an iron head made of a
soft iron material by means of carburizing or nitriding is
disclosed in JP-A-8-206260.
[0007] Application of plasma carburizing or gas carburizing to an
iron head made of a structural alloy steel, stainless steel,
titanium, or a titanium alloy steel so as to increase surface
hardness, thereby enhancing a carry distance of a hit ball is
disclosed in JP-A-10-5376 (paragraphs [0008] to [0017]).
[0008] As compared with an iron head made of stainless steel, an
iron head made of pure iron is lower in material hardness and
produces a softer ball-hit feeling. However, because of low
abrasive resistance, the iron head made of pure iron is easily
damaged on its surface, and angular edges of score lines (lateral
grooves on a face surface) are rounded at an early stage, thereby
making it difficult to impart spin to a hit ball.
[0009] Increasing surface hardness of an iron head made of a soft
iron material or an alloy steel by means of carburizing is
disclosed in the above-mentioned JP-A-8-206260 and JP-A-10-5376,
however, application of carburizing to an iron head made of a pure
iron material is not described therein.
SUMMARY OF THE INVENTION
[0010] The present invention provides a golf club head which is
superior in ball-hit feeling as well as in abrasive resistance.
[0011] According to aspect 1 of the invention, a golf club head
includes a face made of an iron material which is carburized, and
is characterized in that the iron material is pure iron.
[0012] The invention of aspect 2 is the golf club head
characterized in that in the golf club head of aspect 1, purity of
the pure iron is at least 99.8%.
[0013] The invention of aspect 3 is the golf club head
characterized in that in the golf club head of aspect 1, the golf
club head is an iron-type golf club head.
[0014] The invention of aspect 4 is the golf club head
characterized in that in the golf club head of aspect 3, the
iron-type golf club head has a loft angle of 25.degree. or
more.
[0015] The invention of aspect 5 is the golf club head
characterized in that in the golf club head of aspect 3, a
thickness of the face in a vicinity of a center of gravity thereof
falls within a range of 3.5 to 15 mm.
[0016] The invention of aspect 6 is the golf club head
characterized in that in the golf club head of aspect 5, the face
is of smaller thickness on a toe side and on a heel side than in
the vicinity of its center of gravity of the face.
[0017] The invention of aspect 7 is the golf club head
characterized in that in the golf club head of aspect 1, hardness
of a surface of the face falls within a range of HV (hardness value
of Vickers) 180 to 900.
[0018] In particular, since surface hardness of stainless steel
(SUS630)--which is generally regarded to be resistant to damage
when used as an iron head--is about HV 300, hardness of the face
surface is preferably greater than or equal to HV 300.
[0019] Being made of a pure iron material, the golf club head of
the invention provides softball-hit feeling. Accordingly, the golf
club head is particularly suitable for use in an iron having a loft
angle greater than or equal to 25.degree. and from which a soft
touch upon hitting of a ball is expected, and further particularly
suitable for use in a wedge whose loft angle falls within a range
of 400 to 650.
[0020] According to the invention, when purity of an iron material
is greater than or equal to 99.8%, ball-hit feeling becomes soft.
Accordingly, carbon content is preferably 0.02% or lower. When an
iron material having a high purity of 99.995% or higher is
employed, ball-hit feeling becomes fairly soft, and stainless
property is also improved, which is advantageous.
[0021] According to the invention, a surface of a head made of the
pure iron is subjected to carburizing. Accordingly, the head
exhibits favorable abrasive resistance.
[0022] The golf club head according to the invention is suitable
for application to an iron head as described above, however, being
made of pure iron, the face may have insufficient strength. To this
end, the face in the vicinity of a center of gravity at which a
ball hits is preferably reinforced so as to be 3.5 to 15 mm in
thickness. In addition, when thickness of the face in the vicinity
of the center of gravity is increased, a fairly favorable tactile
response is obtained when a ball is hit in the vicinity of the
center of gravity (a so-called hitting of the ball center with the
gravity center of a head).
[0023] Meanwhile, in order to suppress an increase in weight of the
iron head, the following is preferable, that is, thickness in the
vicinity of the center of gravity of the face is increased while
thicknesses of the remaining portions are rendered smaller. More
specifically, the face is preferably smaller in thickness on its
toe side and on its heel side than in the vicinity of its center of
gravity.
[0024] According to the invention, carburizing is preferably
applied so that surface hardness of the face falls within a range
of about HV 180 to 900.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a perspective view of an iron-type golf club head
according to an embodiment of the invention, as viewed from the
rear; and
[0026] FIG. 2 is a side view of the iron-type golf club head
according to the embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Hereinafter, the invention will be described further in
detail by reference to the drawings. FIG. 1 is a perspective view
of a golf club head according to an embodiment of the invention, as
viewed from the rear. FIG. 2 is a side view of the same as viewed
from the toe side thereof.
[0028] An iron-type golf club head 1 has a face 2 which has a face
surface 2f of a flat shape, and a hosel 3 which is continuous with
the face 2 on its heel side. A shaft insertion hole 4 is disposed
in the hosel 3. A tip of a golf club shaft is inserted into the
shaft insertion hole 4, and fixedly attached thereto by means of an
adhesive.
[0029] The golf club head 1 shown in the drawings is a wedge whose
loft angle is 45.degree.. On the backside of the golf club head 1,
a protrusion 5 protruding rearward in the vicinity of the center in
a toe-heel direction is disposed. The face 2 is substantially
uniform in thickness, except for the protrusion 5.
[0030] Meanwhile, the face 2 has its greatest thickness at a sole 6
side (bottom section side), and thickness is gradually reduced
upward.
[0031] The protrusion 5 is located rearward of the center of
gravity of the face 2 (i.e., rearward in a state where the sole of
the head 1 is in contact with the ground).
[0032] The protrusion 5 is preferably located within a range of
about 10 to 90%, particularly preferably about 20 to 80%, in terms
of a ratio of a total length of the head 1 in the toe-heel
direction and a distance from the protrusion 5 to the farther of
the toe and the heel.
[0033] A lowest portion of the protrusion 5 desirably reaches the
sole 6. Accordingly, the center of gravity of the head 1 can be
lowered. In addition, in the embodiment, the outer surface of the
protrusion 5 is rendered smoothly continuous with the sole 6 as
shown in FIG. 2. When configured as above, the lower portion of the
protrusion 5 can be utilized as a bounce angle of the head 1.
[0034] A material of the golf club head 1 is pure iron having a
high purity of at least 99.995%, for instance, within a range of
99.995 to 99.9999%. The head 1 is subjected to carburizing so that
carbon diffuses to a range of about 0.2 to 0.5 mm from the surface.
The carburizing may be applied either only onto the face surface 2f
or onto the whole head. The carburizing may be either gas
carburizing or plasma carburizing.
[0035] As a result of the carburizing, surface hardness of the head
1 is preferably rendered HV 180 to 900, particularly preferably HV
300 to 900, further preferably HV 300 to 800.
[0036] By virtue of being made of pure iron of high purity, the
golf club head 1 configured as above provides soft ball-hit feeling
and is superior in stainless property. Furthermore, by virtue of
being carburized, the golf club head 1 is superior in abrasive
resistance.
[0037] A surface of a soft iron material, such as S20C, which is
generally employed for an iron head, is hardened by means of
carburizing, however, when the carburized portion is lost as a
result of damage or the like, rust is formed. However, when pure
iron of high purity is employed, by means of carburizing the entire
head, the shape of the head is maintained, and rust is hardly
formed even when damage extends to a great depth.
[0038] The golf club head 1 is provided with the protrusion 5.
Accordingly, the face 2 is high in strength, and the golf club head
1 is fairly superior in tactile response when a ball is hit in the
vicinity of the center of gravity of the face. In addition, the
golf club head 1 has the center of gravity at a deep position, and
therefore a wide sweet area.
[0039] Of the golf club head 1, the protrusion 5 reaches the sole
6. Accordingly, the center of gravity is at a low position, thereby
facilitating hitting a ball high.
[0040] The golf club head of the invention is suitable for an iron
head whose loft angle is greater than or equal to 25.degree.,
particularly suitable for a wedge-type head whose loft angle is
greater than or equal to 40.degree.. However, the golf club head is
also applicable to a head of a fairway wood club or utility club
made of an iron material.
[0041] A member of a material of high specific gravity, such as
tungsten, may be attached onto the sole of the golf club head of
the invention. In addition, a hollow may be disposed inside the
face, and filled with a vibration absorption material such as
rubber or elastomer.
* * * * *