Golf club head or face

A striking face for golf clubs, such as a driver, iron or putter, includes zones of the same or different material arranged to create a desired "feel" to the golfer and/or produce a desired effect on the golf ball. For instance, the zones can be arranged to create a variation in mechanical properties across the striking face. The zones can be created by using "pixels" such as round or hexagonal rods arranged with their central axes perpendicular to the striking face. Pixels of a first material such as a shape memory alloy such as superelastic NiTi can be arranged in one or more concentric patterns and the remainder of the striking face can be made up of pixels of a second material such as beta-titanium, martensitic NiTi or stainless steel. The superelastic NiTi pixels can thus create a sweet spot on the striking face of the club.

FIELD OF THE INVENTION 
The invention relates to improvements in construction of golf club heads 
and faces for golf clubs such as a driver, iron or putter. 
BACKGROUND OF THE INVENTION 
A large variety of materials have been proposed and in fact used and 
offered commercially as golf club heads and faces. These materials have 
been applied monolithically or as inserts in the club face in an attempt 
to achieve more distance and/or more control over the ball. The list of 
materials includes polymers, ceramics, and metals, typically the most 
common, stainless steels, BeCu, and lately various titanium alloys, and 
shape memory materials such as NiTi based and copper based alloys. 
Each of these materials has individual properties, different from each 
other but basically uniform unto themselves and hence provide a surface on 
a golf club that impacts the golf ball with essentially uniform mechanical 
properties across the face. For example, a typical titanium alloy such as 
Titanium 6-4 has a modulus of about 15 million psi and a yield strength of 
about 120,000 psi at a strain of less than 1%. Other materials will have 
different moduli and different yield strengths with different associated 
strain levels but as noted uniform properties as to themselves as used on 
the face of a golf club. 
Since the mechanical characteristics (club speed, materials properties, 
geometry) at the impact of the club face with the ball determine the 
course (trajectory, distance, dispersion) of the ball; control of the 
materials properties can be key to control of the course of the ball. Club 
head speed and geometry being constant or independent of the specific 
properties of the material used as the impact surface of the club. 
SUMMARY OF THE INVENTION 
The invention provides a golf ball striking face of a golf club wherein 
first and second zones of material are distributed across the striking 
face, one or more of the first zones being surrounded by one or more of 
the second zones and the one or more first zones having a higher or lower 
modulus of elasticity than the one or more second zones. The first and 
second zones can be differentially heat treated zones of a unitary piece 
of metallic material. Alternatively, a plurality of the first zones can 
comprise discrete pieces of a first material such as a shape memory alloy 
and the second zone can comprise a unitary piece of a second material such 
as .beta.-titanium or stainless steel wherein the first zones are embedded 
in the second material. 
According to various embodiments of the invention, a plurality of the first 
zones can comprise individual wire segments arranged in a pattern with 
central axes of the wire segments intersecting an exposed surface of the 
striking face. The striking face can be planar or non-planar. A plurality 
of the first zones can comprise discrete pieces arranged in a pattern and 
the second zone can comprise a frame surrounding the first zones. The 
first zones can have various shapes such as polyhedral shapes, cylindrical 
shapes or any other desired shape. A plurality of the second zones can be 
separated by a plurality of the first zones such as alternating rings of 
first and second zones. For example, the first zones can comprise an 
annular ring and the second zones can include an inner second zone 
surrounded by the first zone and an outer second zone surrounding the 
first zone. The first zones can comprise a perimeter weighting arrangement 
of an insert or club head of a golf club. Alternatively, third zones of 
material can surround the first and second zones wherein the third zones 
comprise a dense material providing perimeter weighting of an insert or 
club head of a golf club. The first zones can comprise solid or hollow 
metallic members. For example, the one or more first zones can comprise 
wires of single crystal CuNiAl and the wires can be arranged with central 
axes thereof intersecting the striking face.

DETAILED DESCRIPTION OF THE INVENTION 
The invention allows the mechanical properties of the striking face of a 
golf club to be controlled and varied at will in incremental areas on the 
impact face of the club of as small as 0.0001 square inches. Use of the 
invention can hence allow the properties of the club face to vary in any 
pattern over the impact area. As shown in FIG. 1, an elliptically-shaped 
"sweet spot" 2 on the club face 4 of a driver-type golf club 6 can be 
created that varies mechanical properties in concentric rings (or any 
other desirable patterns) in the impact area from high modulus to low 
modulus and/or any combination of high yield strength and elastic strain 
characteristics. An analogy to aid in understanding the invention, is a TV 
screen. Picture the TV screen as the impact area of the golf club and the 
individual pixels as individually selectable materials from the whole 
gamut of available materials. One can then see that any conceivable 
pattern or combination of materials properties can be achieved on the 
"screen" (impact face) by simply selecting the pixels, as desired, by 
analogy as a TV image on the screen can be generated. Further picture the 
individual pixels themselves as having selectable geometry such as round 
or hexagonal shape. For example, if hexagonal geometry were chosen for 
individual pixels, the pixels would stack in a manner essentially "tight 
packed" allowing almost no space between individual pixels while if a 
round geometry is chosen, the stacked pixels 8 would create interstices 10 
(see FIG. 2) between pixels that in turn could be made from any desirable 
material either the same or different from the round pixels themselves. It 
can be seen that an infinite combination of materials properties can be 
created by the combination of choice of "pixel" size and shape and 
material. The range of the invention allows, at one end uniform properties 
across the golf club face by selection of a single material, and at the 
other end an infinite variation of properties in any pattern across the 
face, by selection of the "pixel" size, shape and material. 
The method to create the striking face according to the invention is quite 
simple. Using the TV screen analogy, picture the pixels as the ends of 
individual wires of selected materials such as titanium or polymer or 
preferably highly elastic shape memory materials (e.g., NiTi based 
materials). As shown in FIG. 3, the hexagonal-shaped wires 12 are tightly 
packed into a frame 14 and bonded in a matrix of epoxy polymer (or 
sintered metal powder or solder or other adhesive matrix). This frame is 
made to the proper size for an insert 16 on the face of a golf club, 
either a driver or an "iron" or putter. The framed matrix of "pixels" of 
wire is then formed by machining or grinding to club face geometry and 
applied to a club. The resulting insert 16 as noted above can be designed 
to any desirable combination of materials properties simply by selecting 
the desired wire materials and diameters or cross sectional geometry. 
FIGS. 4-7 illustrate the invention in several forms. FIG. 4 shows round 
"pixels" 18 of uniform diameter in a matrix 20 of epoxy polymer. FIG. 5 
shows the pixels 22 as tight packed hexagon cross sections, FIG. 6 shows a 
frame 24 which mates with the hexagon-shaped pixels, and FIG. 7 shows a 
combination including a variation of pixel sizes 26,28. Note that the 
frame can be retained as part of the insert or removed after the "pixels" 
are bonded together. 
As noted above the pixels may also vary in material selection. FIG. 1 
illustrates an elliptical "sweet spot" 2 in which the central zone is of a 
material with a high modulus and progressively the modulus is varied 
toward the borders of the impact face by selecting materials with 
progressively lower modulus. Of course, the opposite combination of 
materials properties (e.g., low modulus at the center/high modulus at the 
outside) could be implemented or any other combination or a uniform 
material could be selected. 
The preferred embodiments of the invention include versions designed for 
maximum control (minimum dispersion), maximum distance, or ideal 
combinations of distance and control. Various patterns for the impact zone 
are illustrated in FIGS. 8-16 wherein pixels 
30,32,34,36,38,40,42,44,46,48,50 are arranged within frames 
52,54,56,58,60,62,64. 
The thickness of the "pixel" matrix can also be varied to create a "z" axis 
variation in mechanical response of the club face. This thickness 
variation can be accomplished by machining of the front or back or both 
sides of the framed insert or the impact surface of the insert can consist 
of shorter and longer "pixels" that create a 3 dimensional effect on the 
impact surface as illustrated in FIG. 14 wherein striking face 66 has a 
curvature of radius R and the pixels 46 increase in length towards the 
middle of frame 60. Since materials can be individually selected for 
properties, surface geometry of the impact surface can also be modified 
and customized by selective chemical etching of the surface. For example, 
if a combination of titanium-nickel and aluminum "pixels" were selected, 
chemical etching of the impact surface using a strong basic solution would 
result in the aluminum elements being etched away at a rate much higher 
than the nickel-titanium materials. The surface therefore would exhibit 
raised nickel-titanium elements among lowered aluminum elements. This same 
basic process can be applied to a variety of materials including polymers 
to achieve a surface on the impact zone to idealize grip or spin imparted 
to the ball similar to the now conventional grooves, dots, holes and 
indents found on club faces. This process can also be used to produce 
differences in coloration of the materials, which by controlling patterns 
of application can be used to produce visually observable logos, designs 
and/or service marks such as company names on the surface to the inserts. 
The frame constraining the pixel matrix can be made of materials such as 
stainless steel, by machining, forging or casting. A polymer frame may 
also be created by molding or machining. A temporary frame may be used to 
create the insert form as a matrix bonded together by epoxy resin and then 
the frame may be removed leaving a frameless insert for application to the 
club face in an appropriate recess or receiving cavity on the club. The 
back side of the "pixel" matrix may be supported by the frame structure or 
the receiving cavity of the club may support the backside of the matrix or 
both in combination. 
In another variation of the invention, the individual wires 48 ("pixels"), 
may be curved or bowed (see FIG. 15) to allow both compression and bending 
strain upon impact with the ball. The individual pixels 50 may also be 
hollow; for example, thin wall tubes either empty or the lumen filled with 
another material such as polymer or alternately filled or partially filled 
with metal or polymer or ceramic material, as shown in FIG. 16. 
The invention is additionally illustrated in connection with the following 
Examples which are to be considered as illustrative of the present 
invention. It should be understood, however, that the invention is not 
limited to the specific details of the Examples. 
"Driver" Example 
An insert for a golf club "driver" consisting of optimized elastic 
nickel-titanium wires and beta titanium wires in an epoxy matrix with the 
higher modulus beta titanium wires forming an outer circular zone of 
impact and the lower modulus nickel-titanium forming a circular inner zone 
of impact. This embodiment allows a combination of long distance from the 
high modulus beta titanium and control from the lower modulus very highly 
elastic non linear strain characteristics of the nickel-titanium. This 
arrangement approximates the strain distribution on the ball as it is 
deformed by the face of the club. Closer approximations are possible by 
reducing the size of the pixels and adding a third or fourth material and 
so on with moduli progressively varying. The "opposite" example could 
consist of high modulus beta titanium or even higher modulus stainless 
steel forming an inner zone with NiTi lower modulus forming an outer zone. 
"Iron" Example 
An insert for a golf club "iron" consisting of a matrix of hexagonal wires 
per the invention made from highly damping superelastic NiTi alloy or a 
combination of superelastic NiTi and martensitic NiTi alloy materials. 
This embodiment would allow a solid yet vibration reduced feel upon impact 
since the NiTi material in a superelastic or optimized elastic condition 
has a damping effect resulting from energy absorption deriving from its 
stress/strain hysterises behavior. 
"Putter" Example 
An insert for a golf club putter consisting of a matrix of martensitic NiTi 
wires alone or in combination with polymer wires. This embodiment is 
designed to maximize damping (vibration reduction) on impact with a 
resulting "dead" or "soft hit" feel for maximum control of the ball in 
putting. 
"Differentially Heated Treated" Example 
FIG. 17 shows an insert 70 for a golf ball striking surface of a golf club 
wherein the insert is a solid piece of NiTi based shape memory alloy. The 
solid piece of NiTi is differentially heat treated such as in a uniform or 
non-uniform pattern to control the mechanical properties across the 
interface and achieve an effect similar to the "pixel" approach discussed 
above. The differential heat treatment preferably provides finite zones 72 
surrounded by or surrounding adjacent zones which are unaffected by the 
heat treatment. The heat treatment can be implemented, for example, by 
patterning electrodes arranged perpendicular to and opposing the surface 
being heat treated and passing AC or DC current through the electrodes. 
The heat treatment step can be carried out by running electrical current 
from electrode to electrode through the material in order to effect 
localized heating and provide one or more heat treated zones corresponding 
to the shape or shapes of the opposed electrodes. In FIG. 17, a 
nickel-titanium based shape memory alloy insert 70 for a club face is 
located between a pair of opposed electrodes 74,76. FIG. 18 shows a plan 
view of the NiTi insert 70 differentially heat treated in FIG. 17. As 
shown in FIG. 18, the heat treated zone 72 is circular in shape. In heat 
treating the insert, a single pair of electrodes could be used to 
sequentially provide a series of heat treated zones 72 or a plurality of 
electrodes provided in a desired pattern and having a desired 
configuration could be used to create any desired pattern of heat treated 
zones. 
FIGS. 19-21 show examples of patterns of heat treated zones 78,80,82 which 
can be obtained by differentially heat treating NiTi 84,86,88 inserts for 
golf club faces. As shown in these figures, by patterning the electrodes 
and/or by the geometry of the electrodes themselves, differential 
mechanical properties can be achieved in large variety of patterns that 
can be idealized for control of the flight of a golf ball. FIG. 19 shows a 
heat treated zone 78 in the shape of an annular ring and such a heat 
treated zone could be created by a pair of opposed tubular electrodes. 
FIG. 20 shows a ring of circular heat treated zones which together form an 
annular zone 80 created by one or more pairs of opposed electrodes of the 
type shown in FIG. 17. FIG. 21 shows an example of "strip" heat treated 
zones 82 created by one or more pairs of opposed strip electrodes (e.g., 
plate-type electrodes). 
"Composite" Example 
FIGS. 22-23 show an example of a composite insert 90 for a striking face of 
a golf club. As shown in FIG. 22, the insert includes a base material 92 
having one or more embedded members 94 of a material selected for purposes 
of modifying the properties of the insert. For instance, as shown in FIG. 
22, the additional members 94 can be spaced more closely together in the 
central region of the insert than at the outer edges thereof. As shown in 
FIG. 23, the base material can include grooves 96 for receiving the 
additional members 94. The grooves can be provided in any desired pattern 
such as a uniform pattern or non-uniform pattern (e.g., the grooves can be 
provided with progressively increasing spacing therebetween towards the 
outer periphery of the insert). The material of the inserts preferably 
provides a different modulus than the base material. Although the grooves 
are shown as extending vertically the grooves could extend in any desired 
direction or have any desired shape (e.g., the grooves could be provided 
in a horizontal, angled or mixed pattern which combines more than one 
shape or orientation of the grooves). 
"CuNiAl Single Crystal" Example 
An insert for a striking face of a golf club includes "pixels" (as 
described earlier) of single crystal CuNiAl. Such an insert would allow 
much greater deformations of the club insert striking surface. This 
material has extreme strain ability to deform elastically up to 12-14% 
strain with a "plateau" at low stress and full elastic recovery with very 
low hysteresis. FIG. 24 is a stress/strain curve of a wire sample of 
single crystal CuNiAl having a diameter of 0.060 inch. The strain 
properties of such material would allow a golf ball to remain on the club 
for a longer period of time giving an increased feel of control to the 
user. 
"Perimeter Weighting" Example 
FIG. 25 shows an example of how perimeter weighting can be added to the 
golf club according to the invention. In the embodiment shown, the central 
region 100 of the club face can include a pixel or other arrangement such 
as shown in FIGS. 1-23. The central region is entirely or partly 
surrounded by high density "pixels" 102 such as rods of heavy materials 
such as pure metals (e.g., uranium, tungsten, molybdenum, lead, etc.). The 
perimeter weighting concept allows the striking face to be made much 
thinner. For instance, as shown in FIG. 26, the cross-section of an 
"iron-type" club face 104 having the perimeter weighting 102 can be 
substantially uniform in thickness whereas a conventional cast or forged 
stainless steel iron-type club, such as is shown in FIG. 27, has an 
increased cross-section around the top 106 and bottom 108 thereof. 
The foregoing has described the principles, preferred embodiments and modes 
of operation of the present invention. However, the invention should not 
be construed as being limited to the particular embodiments discussed. 
Thus, the above-described embodiments should be regarded as illustrative 
rather than restrictive, and it should be appreciated that variations may 
be made in those embodiments by workers skilled in the art without 
departing from the scope of the present invention as defined by the 
following claims.