U.S. patent application number 11/927852 was filed with the patent office on 2009-04-30 for golf club head and method of making same.
Invention is credited to Lawrence P. Taylor, Peter T. Thompson.
Application Number | 20090111607 11/927852 |
Document ID | / |
Family ID | 40583568 |
Filed Date | 2009-04-30 |
United States Patent
Application |
20090111607 |
Kind Code |
A1 |
Taylor; Lawrence P. ; et
al. |
April 30, 2009 |
Golf Club Head and Method of Making Same
Abstract
A golf club head is described which has a body that is formed at
least in part from a stainless steel alloy having the following
composition in weight percent: TABLE-US-00001 Carbon 0.25 max.
Manganese 14-20 Silicon up to 2.0 Phosphorus 0.05 max. Sulfur 0.5
max. Chromium 12-22 Nickel 3.5 max. Molybdenum 0.5-4 Copper 2.0
max. Nitrogen 0.2-0.8 Boron 0.06 max. The balance of the alloy is
iron and the usual impurities. The stainless steel alloy provides a
hardness of about 80 HRB up to about 25 HRC. The golf club head
provides a unique combination of high strength and hardness, good
ductility, excellent "feel", and good durability. A method of
making the disclosed golf club head is also described.
Inventors: |
Taylor; Lawrence P.;
(Sinking Spring, PA) ; Thompson; Peter T.;
(Sinking Spring, PA) |
Correspondence
Address: |
DANN, DORFMAN, HERRELL & SKILLMAN
1601 MARKET STREET, SUITE 2400
PHILADELPHIA
PA
19103-2307
US
|
Family ID: |
40583568 |
Appl. No.: |
11/927852 |
Filed: |
October 30, 2007 |
Current U.S.
Class: |
473/350 ;
29/527.6; 473/342 |
Current CPC
Class: |
A63B 53/04 20130101;
A63B 2209/00 20130101; A63B 60/00 20151001; A63B 53/0416 20200801;
A63B 60/54 20151001; A63B 53/047 20130101; Y10T 29/49989
20150115 |
Class at
Publication: |
473/350 ;
473/342; 29/527.6 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Claims
1. A golf club comprising a head that is formed at least in part
from a stainless steel alloy having the following composition in
weight percent: TABLE-US-00004 Carbon 0.25 max. Manganese 14-20
Silicon up to 2.0 Phosphorus 0.05 max. Sulfur 0.5 max. Chromium
12-22 Nickel 3.5 max. Molybdenum 0.5-4 Copper 2.0 max. Nitrogen
0.2-0.8 Boron 0.06 max.
and the balance is iron and the usual impurities; wherein said
stainless steel alloy provides a hardness of about 80 HRB to about
25 HRC.
2. The golf club set forth in claim 1 wherein said head comprises a
body and a face plate assembled together and the body is formed of
said stainless steel alloy.
3. The golf club set forth in claim 2 wherein the face plate is
formed of a material selected from the group consisting of a
precipitation hardenable stainless steel, titanium, and a titanium
alloy.
4. The golf club set forth in claim 1 wherein said head is formed
entirely of said stainless steel alloy.
5. A method of making a golf club head comprising the steps of:
melting charge materials selected to provide a stainless steel
alloy having the following composition in weight percent:
TABLE-US-00005 Carbon 0.25 max. Manganese 14-20 Silicon up to 2.0
Phosphorus 0.05 max. Sulfur 0.5 max. Chromium 12-22 Nickel 3.5 max.
Molybdenum 0.5-4 Copper 2.0 max. Nitrogen 0.2-0.8 Boron 0.06
max.
and the balance is iron and the usual impurities; casting said
stainless steel alloy into a mold; solidifying said stainless steel
alloy in said mold to form a body of a golf club head or a preform
thereof; and then processing said body to provide a finished golf
club head.
6. The method as set forth in claim 5 wherein the step of
processing said body comprises the step of heat treating said golf
club head to provide a hardness of about 80 HRB to about 25
HRC.
7. The method as set forth in claim 5 wherein the step of casting
the stainless steel alloy comprises the step of investment casting
the stainless steel alloy.
8. The method as set forth in claim 6 wherein the step of
processing the body of said golf club head comprises the step of
machining the body to finished dimensions.
9. The method as set forth in claim 5 wherein the step of
processing said body comprises the steps of cold working said body
and then heat treating the cold-worked body to provide a hardness
of about 30 HRC.
10. The method as set forth in claim 5 wherein the step of casting
the stainless steel alloy comprises the step of casting the alloy
into an ingot mold, the step of solidifying the stainless steel
alloy comprises the step of forming bar from said alloy, and the
step of processing the golf club head body comprises the steps of:
forging the bar to provide a semi-finished golf club head; and then
machining the semi-finished golf club head to finished
dimensions.
11. The method as set forth in claim 5 comprising the step of
bonding a face plate to said golf club head body after said
processing step.
12. The method as set forth in claim 11 comprising the step of
forming the face plate from a material selected from the group
consisting of a precipitation hardenable stainless steel, titanium,
and a titanium alloy.
Description
FIELD OF THE INVENTION
[0001] This invention relates to golf club heads and in particular
to an iron golf club head made from a corrosion resistant steel
alloy that provides a unique combination of strength, ductility,
and feel.
BACKGROUND OF THE INVENTION
[0002] Golf club manufacturers are continuously on the lookout for
new golf club materials which provide better "feel" than materials
currently in use. That property is especially desirable in irons
and high-lofted clubs such as wedges. It is believed that a major
component of the "feel" characteristic of a golf club is the sound
and vibration damping characteristics of the metal from which the
club head is manufactured. The overall shape and design of the club
head also contribute to its feel characteristic.
[0003] Another important property for an alloy used in a golf club
head is resistance to corrosion. In this regard, steel alloys
containing relatively high amounts of chromium and/or molybdenum
have been favored. Among the currently used stainless steel
materials are AISI Type 431 and Type 304, and precipitation
hardenable grades such as 15-5, 17-4, 13-8, and the CUSTOM 450 and
CUSTOM 455 stainless alloys. Typically, club heads made from Type
431 and the Type 304 are considered to have better "feel" than club
heads made from the precipitation hardenable grades which have much
higher strength. The fact that the Type 431 and Type 304 alloys
have hardness that is softer than the precipitation hardenable
grades, has led to the belief that hardness is inversely
proportional to "feel".
[0004] Some corrosion resistant non-ferrous alloys such as
copper-beryllium have been used for making golf club heads to
provide a "soft feel". In addition, many of the alloys which are
known for good "feel", such as AISI 8620 and cast iron, are very
soft. However, all of these soft alloys have the disadvantage of
being so soft that they lack the durability of the harder stainless
steel golf club alloys. This lack of durability can be seen in a
lack of resistance to scratching and denting, as well as easier
movement of the loft and lie angles during normal play.
[0005] The loft angle of a golf club is a measure of how far the
face of the club is set relative to a line that is perpendicular to
the ground. The lie angle is the angle at which the shaft comes off
of the club head. In the making of a club, golf club producers
often adjust both the loft and lie angles of the golf club head by
bending the club head. The softer alloys are more easily adjusted,
but their adjustment can change over time from the stresses
inflicted on the head during normal play.
[0006] In view of the foregoing, it would be desirable to have a
golf club head which is made of a corrosion resistant steel alloy
that provides good hardness, strength, and ductility, better "feel"
relative to the known higher strength golf club heads, and better
durability than the known soft club heads.
SUMMARY OF THE INVENTION
[0007] In accordance with a first aspect of this invention, an iron
golf club head is provided which has a body that is formed at least
in part from a stainless steel alloy having the following
composition in weight percent:
TABLE-US-00002 Carbon 0.25 max. Manganese 14-20 Silicon up to 2.0
Phosphorus 0.05 max. Sulfur 0.5 max. Chromium 12-22 Nickel 3.5 max.
Molybdenum 0.5-4 Copper 2.0 max. Nitrogen 0.2-0.8 Boron 0.06
max.
The balance of the alloy is iron and the usual impurities. The
stainless steel alloy provides a hardness of about 80 HRB up to
about 25 HRC where HRB refers to the Rockwell B hardness scale and
HRC refers to the Rockwell C hardness scale. The Rockwell B scale
ends at 100 HRB whereas the Rockwell C scale begins at 20 HRC.
[0008] In accordance with a second aspect of the present invention,
there is provided a method of making a golf club head. The method
includes the following steps. Charge materials are selected and
melted to provide a stainless steel alloy having the following
composition in weight percent:
TABLE-US-00003 Carbon 0.25 max. Manganese 14-20 Silicon up to 2.0
Phosphorus 0.05 max. Sulfur 0.5 max. Chromium 12-22 Nickel 3.5 max.
Molybdenum 0.5-4 Copper 2.0 max. Nitrogen 0.2-0.8 Boron 0.06
max.
and the balance is iron and the usual impurities. The alloy is cast
into a mold and allowed to solidify into the form a body of a golf
club head. The golf club head body is processed to provide a
finished golf club head. The golf club head is then heat treated to
provide a hardness of about 80 HRB-25 HRC if it does not provide
such hardness in the as-cast condition.
BRIEF DESCRIPTION OF THE DRAWING
[0009] The drawing is an exploded perspective view of a multi-piece
golf club head made in accordance with the present invention.
DETAILED DESCRIPTION
[0010] An austenitic stainless steel alloy sold under the
registered trademark "15-15LC" was designed for and has been used
exclusively for making components for the oil-drilling industry,
primarily drill collars. Alloys sold under the mark "15-15LC" are
described and claimed in U.S. Pat. No. 3,904,401 and U.S. Pat. No.
5,308,877, both of which are incorporated herein by reference.
[0011] The inventors have discovered that the 15-15LC alloy has
properties that also make it highly suitable for iron golf club
heads. The term "iron" as used herein, refers to the golf clubs
known as irons, as opposed to other types of golf clubs referred to
as woods and putters. As used herein the term "iron golf club"
includes golf clubs known as wedges.
[0012] The golf club head according to the present invention
departs from the state of the art in iron golf clubs because it is
made from an austenitic stainless steel alloy having the following
weight percent composition: up to about 0.25% max. carbon; about
14-20% manganese; up to about 2.0% silicon; up to about 0.05% max.
phosphorus; up to about 0.5% max. sulfur; about 12-22% chromium; up
to about 3.5% max. nickel; about 0.5-4% molybdenum; up to about
2.0% max. copper; 0.2-0.8% nitrogen; and up to about 0.06% max.
boron. The balance of the alloy is iron and the usual impurities
present in commercial grades of stainless steel alloys. Preferably,
the stainless steel alloy comprises the following, in weight
percent: up to about 0.15% max. carbon; about 16-18% manganese; up
to about 1.0%, better yet, not more than about 0.75% silicon; up to
about 0.03% max. phosphorus; not more than about 0.03% max. sulfur;
about 16-19% chromium; up to about 2.5% max., better yet, not more
than about 1.5% nickel; about 0.75-2.5% molybdenum; up to about
2.0% max. copper; 0.3-0.7%, better yet, about 0.4-0.6% nitrogen;
and up to about 0.01% max. boron.
[0013] An iron golf club head made in accordance with the present
invention has a one-piece design or a multi-piece design. The
one-piece embodiment is preferably produced by investment casting
or by forging. Examples of multi-piece golf club heads are shown
and described in U.S. Pat. Nos. 7,014,571 and 7,207,899, the
disclosures of which are incorporated herein by reference.
[0014] The cast form is produced by melting charge materials to
make the stainless steel alloy described above. The molten alloy is
then cast into a ceramic mold having a cavity that defines the
basic shape of the golf club head. After the alloy solidifies and
cools, the mold is removed to yield a preform of the golf club
head.
[0015] The forged form of the club head according to this invention
is produced by melting the stainless steel alloy and casting it
into an ingot. The ingot is hot worked to an intermediate form,
preferably bar. The bar is then cut into segments that approximate
the size of the golf club head. The bar segments are then hot
forged with dies that define the basic shape of the golf club
head.
[0016] It is also contemplated that a golf club head according to
the present invention can be made by powder metallurgy techniques.
In such a process the stainless steel alloy described above is
melted and then atomized, preferably with nitrogen gas, to form
metal powder. The metal powder is filled into a die mold having a
cavity that defines the basic shape of the golf club head. The
metal powder is then consolidated such as by sintering, hot
isostatic pressing, or cold isostatic pressing to form a near net
shape of the desired golf club head preform.
[0017] In any of the foregoing processes, the golf club head
preform is preferably machined to its finished dimensions and
shape. The club head is then ground and polished as necessary to
provide an aesthetic appearance. The hardness for the golf club
application is about 80 HRB to 25 HRC to provide good durability.
That level of hardness can be achieved in the as-cast club head
because the material may self-anneal. If the desired hardness is
not provided in the as-cast condition, then the cast club head can
be annealed at about 1900-2100.degree. F. for about one hour.
Preferably, the club head is heat treated to a hardness of about 85
to 95 HRB. For certain types of irons where additional hardness and
strength is desired, such as in the long or intermediate irons, the
as-cast golf club head can be cold worked, such as by cold forging,
prior to the finish machining operations. The cold worked club head
would then be annealed to achieve its final hardness, preferably
about 30 HRC.
[0018] In accordance with another embodiment of the golf club head
of this invention, as shown in the drawing, there is provided a
multi-piece iron club head 10. The multi-piece head 10 includes a
body 20 that is preferably made from an austenitic stainless steel
alloy such as the 15-15LC alloy described above. The multi-piece
head 10 also includes a face plate 30. The face plate 30 is made of
a harder material than the body 20. Preferred materials would be a
precipitation hardenable stainless steel alloy, titanium, or a
titanium alloy. The face plate is attached/bonded to the body by
welding, brazing, or by mechanical means, such as press fitting or
shrink fitting.
[0019] We have found that the large amount of manganese present in
this alloy benefits the sound and the dampening characteristics of
a club head made from this alloy, as compared to club heads made
from other stainless steels which significantly less manganese. In
addition to the good hardness, strength, and "feel" provided by the
club head according to this invention, the club head according to
this invention also has excellent ductility and toughness. The
latter two properties are desirable because they permit bending of
the hosel, the portion of the club head that connects to the shaft,
in order to adjust the loft and lie angles of the club. Since this
alloy has higher relative strength than the known "soft" golf club
alloys, the loft and lie angles of the club head are less likely to
change during normal play.
[0020] It will be recognized by those skilled in the art that
changes or modifications may be made to the above-described
embodiments without departing from the broad inventive concepts of
the invention. It is understood, therefore, that the invention is
not limited to the particular embodiments that are described, but
is intended to cover all modifications and changes within the scope
and spirit of the invention as described above and set forth in the
appended claims.
* * * * *