U.S. patent application number 09/971154 was filed with the patent office on 2002-06-27 for golf club.
Invention is credited to Chaen, Kiyotaka, Iwata, Mototaka.
Application Number | 20020082118 09/971154 |
Document ID | / |
Family ID | 18813802 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020082118 |
Kind Code |
A1 |
Iwata, Mototaka ; et
al. |
June 27, 2002 |
Golf club
Abstract
At least a part of a head portion of a golf club consists of
stainless steel containing throughout 0.1% or more to 0.3% or less
by weight of nitrogen. Further, at least a part of the head portion
consists of a corrosion-resistant metal having a yield strength of
0.2% of 350 MPa or more to 600 MPa or less, a tensile strength of
500 MPa or more to 800 MPa or less and an elongation after fracture
of 40% or more to 60% or less.
Inventors: |
Iwata, Mototaka; (Osaka,
JP) ; Chaen, Kiyotaka; (Osaka, JP) |
Correspondence
Address: |
TROUTMAN SANDERS LLP
BANK OF AMERICA PLAZA, SUITE 5200
600 PEACHTREE STREET , NE
ATLANTA
GA
30308-2216
US
|
Family ID: |
18813802 |
Appl. No.: |
09/971154 |
Filed: |
October 4, 2001 |
Current U.S.
Class: |
473/349 ;
473/345; 473/350 |
Current CPC
Class: |
A63B 53/047 20130101;
A63B 2209/00 20130101; C22C 38/001 20130101; A63B 60/00 20151001;
A63B 53/0416 20200801; A63B 53/0408 20200801; C22C 38/40 20130101;
C22C 38/10 20130101; A63B 53/04 20130101 |
Class at
Publication: |
473/349 ;
473/345; 473/350 |
International
Class: |
A63B 053/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 7, 2000 |
JP |
2000-338616(P) |
Claims
What is claimed is:
1. A golf club comprising a head portion, wherein at least a part
of said head portion consists of stainless steel containing
throughout at least 0.1% by weight to at most 0.3% by weight of
nitrogen.
2. The golf club according to claim 1, wherein said stainless steel
includes at most 0.08% by weight of carbon, at most 1.00% by weight
of silicon, at most 2.5% by weight of manganese, at most 0.045% by
weight of phosphorus, at most 0.03% by weight of sulfur, at most
0.15% by weight of niobium, at least 18% by weight to at most 20%
by weight of chromium, and at least 7% by weight to at most 10.5%
by weight of nickel, with the remainder consisting of iron and
inevitable impurity.
3. The golf club according to claim 1, wherein said head portion
has a face portion and a neck portion, and at least one of said
face portion and said neck portion consists of said stainless
steel.
4. The golf club according to claim 3, wherein thickness of a
peripheral portion of said face portion is made smaller than
thickness of a center portion of said face portion.
5. The golf club according to claim 1, wherein said head portion
has a hollow structure and has a face portion consisting of said
stainless steel, and thickness of said face portion is at least 1
mm to at most 2.5 mm.
6. The golf club according to claim 5, wherein thickness of a
peripheral portion of said face portion is made smaller than
thickness of a center portion of said face portion.
7. The golf club according to claim 3, wherein said neck portion
has an outer diameter of at least 8.5 mm to at most 12.5 mm and an
inner diameter of at least 9 mm to at most 10 mm, and said neck
portion has a length of at least 30 mm to at most 80 mm.
8. A golf club comprising a head portion, wherein at least a part
of said head portion consists of a corrosion-resistant material
having a yield strength of 0.2% of at least 350 MPa to at most 600
MPa, a tensile strength of at least 500 MPa to at most 800 MPa and
an elongation after fracture of at least 40% to at most 60%.
9. The golf club according to claim 8, wherein said yield strength
of 0.2% is at least 400 MPa to at most 600 MPa, and said tensile
strength is at least 600 MPa to at most 800 MPa.
Description
[0001] This application claims priority from Japanese Patent
Application No. 2000-338616(P) bearing the filing date of Nov. 7,
2000.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a golf club, and more
particularly to a golf club having a head portion formed of a
prescribed composition of material.
[0004] 2. Description of the Background Art
[0005] Conventionally, austenite 18 Cr--8Ni (SUS304 according to
Japanese Industrial Standards (JIS) code), ferritic 17Cr stainless
steel (SUS430 according to JIS), precipitation hardening 17Cr--4Ni
(SUS630 according to JIS) or the like are generally used for a head
portion made of stainless steel. S25C of carbon steels for machine
structural use is also used.
[0006] Japanese Utility Model Laying-Open No. 2-143969 describes an
invention in which nitrogen is introduced into a hitting surface of
a head portion by ion implantation or ion beam mixing.
[0007] Further, Japanese Patent Laying-Open No. 6-269520 discloses
a method of manufacturing a golf club head, wherein stainless steel
hardened by sub-zero treatment is forged into a head shape, which
is subjected to solution treatment in a nitrogen atmosphere,
followed by sub-zero treatment.
[0008] Still further, Japanese Patent Laying-Open No. 11-206930
discloses a method of manufacturing a golf club head, wherein
austenite material is formed into a head, which is subjected to
solution treatment in vacuo at 1050-1070--for two hours, followed
by cooling in a nitrogen atmosphere.
[0009] SUS304 is preferably used for fabricating an inexpensive
head portion. SUS304, however, is not strong enough to wear well,
unless a face portion is made thick. This makes it difficult to
fabricate a thin large-size head.
[0010] Then, in order to make a face portion and a head portion
thin, SUS630 which can be increased in strength by precipitation
hardening by means of heat treatment after fabricating a head
portion is used.
[0011] SUS630, however, is too hard, resulting in a poor feeling of
hitting. Further, a general-size neck portion made of this material
is too strong to bend easily, and thus a lie angle cannot be
adjusted. In addition, since SUS630 is a precipitation hardening
type, it needs to be increased in strength by heat treatment and
therefore requires the cost of this heat treatment.
[0012] Although SUS430, 431 have a strength between SUS304 and
SUS630, they have a relatively poor corrosion resistance among
stainless steel. This causes rusting of a head portion to some
extent. In addition, it is difficult to adjust a lie angle.
[0013] S25C is not strong enough to fabricate a thin, large-size
head. Further, since it has a poor corrosion resistance, a head
surface needs to be plated.
[0014] According to Japanese Utility Model Laying-Open No.
2-143969, a hitting surface is introduced with nitrogen by ion
implantation or ion bean mixing. This increases cost, and in
addition, only the hitting surface is hardened. It follows that
although the strength of the hitting surface becomes high, the
strength of a head internal portion remains low. Therefore, when a
thin, large-size head is fabricated, the strength is not
sufficient.
[0015] According to Japanese Patent Laying-Open No. 6-269520,
although a head surface is softened to provide a good feeling of
hitting, a head internal portion is too strong to adjust an angle
of a neck portion easily. In addition, performing a sub-zero
treatment increases cost.
[0016] According to Japanese Patent Laying-Open No. 11-206930,
nitrogen penetrates only into the vicinity of a head surface. As a
result, although the strength of the head surface becomes high, the
strength of a head internal portion remains low. Therefore, when a
thin, large-size head is fabricated, the strength is not
sufficient.
[0017] Therefore, an object of the present invention is to provide
a golf club including a head portion which enables an easy
adjustment of an angle of a neck portion, allows for fabrication of
a thin, large-size head, and provides a good corrosion
resistance.
SUMMARY OF THE INVENTION
[0018] A golf club in accordance with the present invention
includes a head portion, at least a part of which consists of
stainless steel containing throughout at least 0.1% by weight to at
most 0.3% by weight of nitrogen.
[0019] The inventors contemplate to provide a material for a head
portion, wherein 1) an angle of a neck portion is easily adjusted
when it has a normal neck diameter, 2) the head portion can be
reduced in thickness and increased in size, and 3) the head portion
has a good corrosion resistance. Then, it has been found that such
a material for a head portion that can satisfy all the above
characteristics can result by mixing nitrogen into stainless steel
at the stage of a raw material before forging or casting to vary
the strength of the material according to a nitrogen content. More
specifically, it has been found that inclusion of at least 0.1% by
weight to at most 0.3% by weight of nitrogen throughout stainless
steel can attain, for example, a yield strength of 0.2% of 350
MPa-470 MPa, a tensile strength of 630 MPa-800 MPa, and an
elongation after fracture of 40%-57% as shown in Table 1. As a
result, by using the above mentioned material for a neck portion,
the angle adjustment of the neck portion becomes easy even when it
has a normal neck diameter, and such a strength can be attained
that allows for a thin, large-size head portion. Further, the use
of stainless steel as a base material can ensure corrosion
resistance.
[0020] The aforementioned stainless steel preferably includes at
least 0% by weight preferably 0.001% by weight) to at most 0.08% by
weight of carbon, at least 0% by weight (preferably 0.001% by
weight) to at most 1.00% by weight of silicon, at least 0% by
weight preferably 0.001% by weight) to at most 2.5% by weight of
manganese, at least 0% by weight (preferably 0.001% by weight) to
at most 0.045% by weight of phosphorus, at least 0% by weight
(preferably 0.001% by weight) to at most 0.03% by weight of sulfur,
at least 0% by weight (preferably 0.001% by weight) to at most
0.15% by weight of niobium, at least 18% by weight to at most 20%
by weight of chromium, and at least 7% by weight to at most 10.5%
by weight of nickel, with the remainder consisting of iron and
inevitable impurity.
[0021] As described above, when SUS304 material is employed as
stainless steel serving as a base material, nitrogen atoms permeate
throughout the atoms constituting SUS304 material, resulting in a
particularly preferred value of yield strength of 0.2%, tensile
strength, elongation after fracture and the like of the material,
as shown in Table 1. Furthermore, inclusion of a large amount of
nickel and chromium attains an excellent corrosion resistance.
[0022] Preferably, the head portion has a face portion and a neck
portion, at least one of which consists of the aforementioned
stainless steel.
[0023] Further, preferably, the head portion has a hollow
structure, and has a face portion consisting of the aforementioned
stainless steel, and the thickness of the face portion is at least
1 mm to at most 2.5 mm.
[0024] Since the material of the present invention has a relatively
high strength as described above, fabrication of the face portion
with this material can ensure a desired strength even when the
thickness of the face portion is reduced to 1 to 3.0 mm. In
addition, the face portion can be increased in size. Therefore, the
face portion itself can easily flex as the area of that part of the
face portion which can flex at the time of actually hitting a ball
(an effective face area) is increased, thereby improving the
restitution characteristics of the face portion.
[0025] Furthermore, the thickness of the peripheral portion of the
face portion may be made smaller than the thickness of the center
portion of the face portion. The use of the material in accordance
with the present invention can ensure a desired strength even when
the thickness of the peripheral portion of the face portion is
reduced. Therefore, the face portion can be easily flexed, thereby
improving the restitution characteristics of the face portion.
[0026] The dimensional parts of the neck portion are shown in FIG.
1. The length of the neck portion is represented by length L
extending from the end portion of the neck to the ridgeline by the
side of a heel where the neck and a sole face join. The neck
portion shown in FIG. 1 preferably has an outer diameter D of at
least 8.5 mm to at most 12.5 mm, and an inner diameter d of at
least 9 mm to at most 10 mm, and the neck portion preferably has a
length L of at least 30 mm to at most 80 mm.
[0027] By using the material in accordance with the present
invention, the neck portion can be sized similar to a normal golf
club, while the neck portion can be manually bent using tools or
the like relatively easily so that the lie angle or the loft angle
of the neck portion can be adjusted.
[0028] A golf club in accordance with another aspect of the present
invention includes a head portion, at least a part of which
consists of a corrosion-resistant metal with a yield strength of
0.2% of at least 350 MPa to at most 600 MPa, a tensile strength of
at least 500 MPa to at most 800 MPa and an elongation after
fracture of at least 40% to at most 60%. A corrosion-resistant
metal herein refers to a metal which has an excellent corrosion
resistance, such as stainless steel.
[0029] At the time of actually hitting a ball with the above noted
golf club with a normal diameter, the neck portion is bent when the
component material of the neck portion has a yield strength of 0.2%
of less than 200 MPa and a tensile strength of less than 500 MPa.
On the other hand, when the yield strength of 0.2% is more than 600
MPa and the tensile strength is more than 800 MPa, it is difficult
to bend the neck portion manually using tools or the like. Further,
when the yield strength of 0.2% and the tensile strength are within
the above mentioned ranges but the elongation after fracture is
less than 30%, the neck portion is less likely to deform, which
makes it difficult to adjust the angle of the neck portion.
Therefore, when yield strength of 0.2%, tensile strength and
elongation after fracture are within the above ranges, the neck
portion can be prevented from bending at the time of hitting a
ball, while the angle of the neck portion can be adjusted
relatively easily. In addition, since the strength of the material
is relatively high, the head portion can be reduced in thickness
and increased in size, and also be assured of corrosion
resistance.
[0030] The aforementioned yield strength of 0.2% is preferably at
most 400 MPa to at least 600 MPa, and the tensile strength is
preferably at least 600 MPa to at most 800 MPa.
[0031] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is an illustration indicating the dimensions of the
neck portion in the head portion.
[0033] FIG. 2 is an exploded perspective view of the head portion
in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] In the following, an embodiment of the present invention
will be described. The present invention relates to a material for
forming a head portion of a golf club, and is aimed to achieve the
desired characteristics by using stainless steel, which is a metal
having a good corrosion resistance, as a base material, and
properly adjusting the composition of the base material.
[0035] The present invention is applicable for any golf club
whether it is an iron type or a wood type. Shapes of a head
portion, shaft and grip of a golf club may be conventional ones
used generally, and therefore these are not shown herein.
[0036] In accordance with the present invention, at least a part of
a head portion of a golf club consists of stainless steel
containing throughout 0.1% or more to 0.3% or less by weight of
nitrogen.
[0037] Since nitrogen is mixed into stainless steel at the stage of
a raw material before forging or casting, nitrogen is present not
only in the surface of but also throughout the stainless steel.
[0038] A technique of mixing nitrogen will now be described.
Stainless steel which was melted in an electric furnace (molten
metal) is transferred as it is to a refinery. Then, in the
refinery, the chemical composition is adjusted to an intended
component standard range with removal of impurity. Refining of this
stainless steel is normally performed in an anti-oxidization
atmosphere to inhibit oxidization reaction of the included
chromium. At this point, nitrogen gas is blown into the molten
metal so that the molten metal undergoes solid-solution treatment
with nitrogen, resulting in the stainless steel containing a large
amount of nitrogen.
[0039] Nitrogen which is mixed into stainless steel as described
above disperses in the stainless steel as substitutional type
atoms. This increases the strength of stainless steel.
[0040] The inventors considered how much nitrogen could be mixed
into stainless steel to produce such a material for a head portion
in that 1) an angle of a neck portion could be easily adjusted when
it had a normal neck diameter, 2) the head portion could be reduced
in thickness and increased in size, and 3) the head portion had a
good corrosion resistance.
[0041] The following Table 1 shows the relation of a nitrogen
content with the yield strength of 0.2%, tensile strength and
elongation after fracture of the material. Note that SUS304
material was used as a base material.
1TABLE 1 nitrogen content (% by weight) 0 0.1 0.2 0.3 yield
strength of 0.2% (MPa) 260 350 420 470 tensile strength (MPa) 600
630 750 800 elongation after fracture (%) 64 57 49 40
[0042] As shown in Table 1, as the nitrogen content increases, the
yield strength of 0.2% and tensile strength of the material
increase and therefore the strength of the stainless steel
increases. On the other hand, the elongation after fracture
decreases as the nitrogen content increases.
[0043] The nitrogen content, however, has a limit so that it is
difficult to mix more than 0.3% by weight. Further, even if the
nitrogen content exceeds 0.3% by weight, the strength does not
increase accordingly. In addition, as the elongation of the
material decreases, possible damage or crack is more likely to
cause breakage. Still further, an excess amount of a nitrogen
content deteriorates weldability.
[0044] Then, nitrogen content in stainless steel is determined to
be 0.1% or more to 0.3% or less by weight (preferably about 0.2% by
weight). This attained a yield strength of 0.2% of 350 MPa-470 MPa,
a tensile strength of 630 MPa-800 MPa, and an elongation after
fracture of 40%-57% as shown in Table 1.
[0045] The above noted ranges of the yield strength of 0.2% and the
like can increase the strength of the material appropriately, so
that the angle of the neck portion can easily be adjusted when it
has a normal neck diameter, and in addition, a head portion can be
reduced in thickness and increased in size. Further, the use of
stainless steel as a base material can ensure corrosion
resistance.
[0046] Stainless steel serving as a base material is preferably
SUS304, including at least 0% (preferably 0.001%) to at most 0.08%
by weight of carbon, at least 0% (preferably 0.001%) to at most
1.00% by weight of silicon, at least 0% (preferably 0.001%) to at
most 2.5% by weight of manganese, at least 0% (preferably 0.001%)
to at most 0.045% by weight of phosphorus, at least 0% (preferably
0.001%) to at most 0.03% by weight of sulfur, at least 0%
(preferably 0.001%) to at most 0.15% by weight of niobium, at least
18% to at most 20% by weight of chromium, and at least 7% to at
most 10.5% by weight of nickel, with the remainder consisting of
iron and inevitable impurity.
[0047] By employing SUS304 material as stainless steel serving as a
base material as described above, the yield strength of 0.2%,
tensile strength, elongation after fracture and the like fall
within the particularly preferred ranges as shown in Table 1.
Further, inclusion of a large amount of chromium and nickel attains
an excellent corrosion resistance.
[0048] A head portion was fabricated using a material, in which the
present invention described above was embodied, (an embodiment),
which was compared with a head portion using a conventional
stainless steel in terms of yield strength of 0.2%, tensile
strength, corrosion prevention, feeling of hitting, and easiness of
the angle adjustment of the neck portion (neck angle adjustment).
The result is shown in Table 2 below.
2 TABLE 2 neck neck yield tensile corrosion feeling angle bending
strength strength preven- of adjust- in (MPa) (MPa) tion hitting
ment hitting embodiment 400 750 no S25C 280 460 x no SUS3O4 210 550
yes SUS431 650 850 ? ? x no SUS630 750 950 x x no
[0049] A method of manufacturing in accordance with the
aforementioned embodiment will now be described. First, using a
material (JIS SUS304N2) in which about 0.2% by weight of nitrogen
is mixed in SUS304 by the aforementioned technique, a face side
portion 3 into which a face portion and a neck portion are
integrated as shown in FIG. 2 is fabricated by forging. On the
other hand, a back side portion 4 is fabricated using SUS304
material by forging.
[0050] At this point, as shown in FIG. 2, the thickness of center
part 3a of the face portion is made to 2.5 mm, upper part 3b of the
face portion is to 2.1 mm, and lower part 3c of the face portion 3c
is to 2.3 mm. The outer diameter of the neck portion is 12.5 mm,
the inner diameter thereof is 9.5 mm, and the length thereof is 50
mm.
[0051] Then, using a welding rod of SUS304, the face side portion
and the back side portion are welded together. Note that after
welding, thermal treatment is not performed.
[0052] As shown in Table 2, the yield strength of 0.2% and tensile
strength of the head portion manufactured through the above steps
are greater than those of SUS304 and S25C, and smaller than those
of SUS431 and SUS630.
[0053] In other words, it should be understood that the strength is
appropriately increased. Therefore, when a neck portion is formed
of the aforementioned material, the neck portion can be sized
similar to a normal golf club while the neck portion can be
manually bent using tools or the like relatively easily so that the
lie angle and the loft angle of the neck portion can be easily
adjusted.
[0054] It is noted that the outer diameter of the neck portion may
be at least 8.5 mm to at most 12.5 mm, the inner diameter thereof
may be at least 9 mm to at most 10 mm, and the length thereof may
be at least 30 mm to at most 80 mm.
[0055] Furthermore, since the material in accordance with the
present invention has a relatively high strength, it is possible to
provide a head portion in a hollow structure and to reduce the
thickness of a face portion to 3.0 mm or less while increasing the
size of the face portion.
[0056] Accordingly, the face portion itself can easily flex as the
area of that part of the face portion that can flex at the time of
hitting a ball (an effective face area) is increased, thereby
improving the restitution characteristics of the face portion.
[0057] It is noted that the thickness of the face portion may be 1
mm or more to 3.0 mm or less. The use of the material in accordance
with the present invention can reduce the thickness of the face
portion to this extent.
[0058] Furthermore, when the thickness of the peripheral portion of
the face portion is made smaller than that of the center portion of
the face portion as the aforementioned embodiment, the face portion
tends to flex more easily, and therefore the restitution
characteristics of the face portion can further be improved.
[0059] A golf club having a head portion fabricated using the
material of the present invention was evaluated by having a
professional player hit a ball with this club. As a result, it is
appreciated with an impression that "feeling of hitting is very
good", though Table 2 just shows,.
[0060] Since SUS304 is used as a base material, the corrosion
resistance (corrosion prevention) of the head portion of the
present embodiment is excellent as shown in Table 2.
[0061] It is noted that although the face portion and the neck
portion are integrated in the aforementioned embodiment, at least
one of the face portion and the neck portion may consist of the
material of the present invention. Alternatively, the neck portion
and the back portion may be integrated.
[0062] Although the desired characteristics of stainless steel is
achieved by mixing an adequate amount of nitrogen into stainless
steel in accordance with the aforementioned embodiment, it is
assumed that any metal material which can satisfy the condition
described below will bring about the aforementioned effect specific
to the present invention.
[0063] More specifically, it is assumed that any
corrosion-resistant metal can bring about the effect specific to
the present invention as long as it has a yield strength of 0.2% of
at least 350 MPa to at most 600 MPa, a tensile strength of at least
500 MPa to at most 800 MPa, and an elongation after fracture of at
least 40% to at most 60%. A corrosion-resistant metal herein refers
to a metal which has an excellent corrosion resistance, such as
stainless steel.
[0064] An iron based material having a yield strength of 0.2% of
0-600 MPa, a tensile strength of 0-800 MPa, and an elongation after
fracture of 30% or more enables a neck portion with a normal neck
diameter to be bent manually using tools or the like. A yield
strength of 0.2% of less than 200 MPa, however, causes bending of
the neck portion in hitting a ball actually.
[0065] Further, a yield strength of 0.2% of more than 600 MPa, and
a tensile strength of more than 800 MPa make it difficult to bend
the neck portion manually even by means of tools or the like. In
addition, when a yield strength of 0.2% and a tensile strength are
within the above noted ranges but an elongation after fracture is
less than 30%, the neck portion is less likely to deform, which
makes it difficult to adjust the angle of the neck portion.
[0066] Therefore, when the yield strength of 0.2%, tensile strength
and elongation after fracture are set to be within above noted
ranges, bending of the neck portion can be prevented when hitting a
ball actually, while the angle of the neck portion can be adjusted
relatively easily. Furthermore, the relatively high strength allows
for a thin, large-size head portion, and the use of a
corrosion-resistant metal can ensure the corrosion resistance of
the head portion.
[0067] The above noted yield strength of 0.2% is preferably at
least 400 MPa to at most 600 MPa, and the tensile strength is
preferably at least 600 MPa to at most 800 MPa. This makes the
effect of the present invention more prominent.
[0068] According to the present invention, the desired value of the
strength of the material for the head portion can be achieved, so
that the angle of the neck portion can be easily adjusted when it
has a normal neck diameter, and the head portion can be reduced in
thickness and increased in size. Furthermore, the use of a material
having an excellent corrosion resistance as a base material of the
head portion can ensure corrosion resistance.
[0069] Although the present invention has been described and
illustrated in detail, it is clearly understood that the same is by
way of illustration and example only and is not to be taken by way
of limitation, the spirit and scope of the present invention being
limited only by the terms of the appended claims.
* * * * *