U.S. patent application number 10/063849 was filed with the patent office on 2003-01-16 for high moment of inertia composite golf club head.
This patent application is currently assigned to Callaway Golf Company. Invention is credited to Cackett, Matthew T., Fan, Frank H., Helmstetter, Richard C., Murphy, James M., Reyes, Herbert.
Application Number | 20030013547 10/063849 |
Document ID | / |
Family ID | 25169472 |
Filed Date | 2003-01-16 |
United States Patent
Application |
20030013547 |
Kind Code |
A1 |
Helmstetter, Richard C. ; et
al. |
January 16, 2003 |
High moment of inertia composite golf club head
Abstract
A high moment of inertia golf club head composed of a composite
material and having a metal weight strip in a ribbon section is
disclosed herein. The metal strip may be composed of copper,
tungsten or a similar metal. The moment of inertia, Izz, of the
golf club head about a vertical axis Z through the center of
gravity ranges from 3000 g-cm.sup.2 to 5000 g-cm.sup.2, and a
moment of inertia, Iyy, about a horizontal axis Y through the
center of gravity of the golf club head ranges from 1900 g-cm.sup.2
to 2050 g-cm.sup.2. The golf club head is preferably composed of
plies of pre-peg sheets. The volume of the composite golf club head
varies from 300 cm.sup.3 to 700 cm.sup.3.
Inventors: |
Helmstetter, Richard C.;
(Rancho Santa Fe, CA) ; Reyes, Herbert; (Laguna
Niguel, CA) ; Murphy, James M.; (Oceanside, CA)
; Cackett, Matthew T.; (San Diego, CA) ; Fan,
Frank H.; (Carlsbad, CA) |
Correspondence
Address: |
CALLAWAY GOLF C0MPANY
2285 RUTHERFORD ROAD
CARLSBAD
CA
92008
|
Assignee: |
Callaway Golf Company
Carlsbad
CA
|
Family ID: |
25169472 |
Appl. No.: |
10/063849 |
Filed: |
May 17, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10063849 |
May 17, 2002 |
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09796951 |
Feb 27, 2001 |
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09796951 |
Feb 27, 2001 |
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09474688 |
Dec 29, 1999 |
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6386990 |
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09474688 |
Dec 29, 1999 |
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08958723 |
Oct 23, 1997 |
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6010411 |
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Current U.S.
Class: |
473/345 |
Current CPC
Class: |
A63B 53/0458 20200801;
A63B 2209/02 20130101; A63B 60/00 20151001; A63B 60/02 20151001;
B29C 70/865 20130101; A63B 53/0412 20200801; A63B 53/0408 20200801;
A63B 53/0433 20200801; A63B 53/0437 20200801; A63B 53/04 20130101;
B29C 70/342 20130101; B29L 2031/5227 20130101; A63B 2053/0491
20130101; A63B 53/0466 20130101; A63B 53/0416 20200801; A63B 53/02
20130101 |
Class at
Publication: |
473/345 |
International
Class: |
A63B 053/04 |
Claims
We claim as our invention:
1. A golf club head comprising: a body having a hollow interior,
the body composed of a non-metal material; at least one weight
strip composed of a material having a density greater than the
non-metal material, the at least one weight strip disposed within
the body; wherein the body has a volume greater than 300 cm.sup.3
and has a moment of inertia, Izz, greater than 3000 g-cm.sup.2
about a vertical axis Z through the center of gravity of the golf
club head.
2. The golf club head according to claim 1 wherein the body is
composed of a plurality of layers of plies of pre-preg
material.
3. The golf club head according to claim 1 wherein the at least one
weight strip is juxtaposed between layers of the plurality of
layers of plies of pre-preg material.
4. The golf club head according to claim 1 further comprising a
secondary weight member disposed on a sole.
5. The golf club head according to claim 1 wherein the at least one
weight strip is composed of a material selected from the group
consisting of a densified loaded film, copper, tungsten and
bismuth.
6. The golf club head according to claim 1 wherein the moment of
inertia, Izz, about the vertical axis Z through the center of
gravity of the golf club head ranges from 3500 g-cm.sup.2 to 5000
g-cm.sup.2.
7. The golf club head according to claim 1 wherein the at least one
weight strip extends from a toe end of the ribbon to a heel end of
the ribbon.
8. The golf club head according to claim 1 wherein the at least one
weight strip extends along at least fifty percent of the length of
the ribbon.
9. The golf club head according to claim 1 wherein the golf club
head has a moment of inertia, Iyy, of at least 1900 g-cm.sup.2
about a horizontal axis Y through the center of gravity of the golf
club head, the horizontal axis Y orthogonal to vertical axis Z.
10. The golf club head according to claim 1 where in the golf club
head has a volume that ranges from 320 cm.sup.3 to 600
cm.sup.3.
11. The golf club head according to claim 1 wherein the golf club
head has a mass between 150 grams to 250 grams.
12. The golf club head according to claim 1 wherein the moment of
inertia, Iyy, about the horzontal axis Y through the center of
gravity of the golf club head ranges from 1900 g-cm.sup.2 to 2050
g-cm.sup.2.
13. The golf club head according to claim 1 wherein the moment of
inertia, Izz, about the vertical axis Z through the center of
gravity of the golf club head ranges from 3700 g-cm.sup.2 to 5000
g-cm.sup.2.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of pending U.S.
patent application Ser. No. 09/796,951, filed on Feb. 27, 2001,
which is a continuation-in-part application of co-pending U.S.
patent application Ser. No. 09/474,688, filed on Dec. 29, 1999, now
U.S. Pat. No. 6,386,990, which is a continuation-in-part
application of U.S. patent application Ser. No. 08/958,723, filed
on Oct. 23, 1997, and now U.S. Pat. No. 6,010,411, both of which
are hereby incorporated by reference in their entirety.
FEDERAL RESEARCH STATEMENT
[0002] [Not Applicable]
BACKGROUND OF INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to a golf club head. More
specifically, the present invention relates to a golf club head
composed of a composite material.
[0005] 2. Description of the Related Art
[0006] In recent years, substantial attention has been directed
toward the development of golf club heads having desired weight
characteristics and, in particular, toward the development of golf
club heads having a desired center of gravity location. For
example, a designer may want to locate the center of gravity of a
golf club head in a predetermined or preferred position relative to
the face or "sweet spot" of the golf club head to provide greater
distance.
[0007] Because conventional golf club heads are typically made from
metal alloys or other materials having a subhomogeneous density,
the weight characteristics of such golf club heads are typically
defined by their overall shape. Thus, to alter the location of the
center of gravity of a golf club head, it is often necessary to
redesign the shape or configuration of the golf club head. However,
this may adversely impact other desired character of the golf club
head.
[0008] The design process may be further complicated where golf
club heads are manufactured using composite material (typically
carbon reinforced plastic). Because composite materials are
typically less dense than metal and other conventional materials,
composite golf club heads generally require additional weighting to
achieve desired swing weights for finished golf clubs.
[0009] The Rules of Golf, established and interpreted by the United
States Golf Association (USGA) and The Royal and Ancient Golf Club
of Saint Andrews, set forth certain requirements for a golf club
head. The requirements for a golf club head are found in Rule 4 and
Appendix II. A complete description of the Rules of Golf are
available on the USGA web page at www.usga.org. Although the Rules
of Golf do not expressly state specific parameters for a golf club,
Rule 4-1d states that the club head shall be generally plain in
shape, and all parts shall be rigid, structural in nature and
functional.
[0010] Many solutions have been proposed to adjust and/or increase
the weight of composite golf club heads. For example, a weighting
agent or material is often introduced into a cavity within a golf
club head subsequent to manufacture. In the case of wood type golf
club heads, the cavity may be enclosed by the face, sides, sole and
crown of the golf club head. However, it is not uncommon for
cavities also to be formed, for example, in the sole, heel or toe
regions of iron or putter type golf club heads. Because of limited
access to the cavities, how such weighting materials may not be
placed as precisely as desired and may not provide the ability to
adjust the weight of the golf club heads, or the location of the
center of gravity of the golf club heads, very precisely.
Furthermore, such materials may dry and separate from the walls of
the golf club heads during use, adversely affecting the weight of
the golf club heads and possibly creating a distracting sound or
feel when the golf clubs are swung.
[0011] Alternatively, a composite golf club head may be provided
with a solid or foam core. However, the use of solid or foam core
materials has been shown generally to be ineffective for adjusting
the location of the center of gravity and moments of inertia of
golf club heads. The reason for this is that solid or foam core
materials generally have a uniform density, making it difficult to
adjust the location of the center of gravity or moments of inertia
of the golf club head without simultaneously altering the shape or
configuration of the golf club head. Additionally, such materials
may result in voids within the golf club head.
[0012] For a golf club head including composite material, higher
density layers of composite fiber may be provided in the wall of
the golf club head to increase its weight. However, such changes in
the layers of composite material may affect the structural
characteristics of the golf club head.
[0013] In view of the foregoing, there appears to be a substantial
need for improved methods of manufacturing composite golf club
heads and, in particular, for methods that allow for more effective
adjustment of the weight characteristics of golf club heads without
substantially affecting the structural characteristics of the golf
club heads.
[0014] There also appears to be a need for improved composite golf
club heads manufactured in accordance with such methods.
SUMMARY OF INVENTION
[0015] The present invention provides a high moment of inertia
composite golf club head that provides greater performance than
traditional composite golf club heads. The golf club head of the
present invention is able to accomplish this by providing a
multiple of weight components in the sole and ribbon(s) of the golf
club head.
[0016] One aspect of the present invention is a golf club head
including a body with a weight strip. The body has a hollow
interior and is composed of a composite material. The body has a
face, a sole, a crown, a ribbon juxtaposed by the sole and the
crown, a heel end and a toe end. The weight strip is composed of a
material having a density greater than the composite material, and
is disposed in the ribbon. The body has a volume greater than 300
cm.sup.3 and has a moment of inertia, Izz, greater than 3000
g-cm.sup.2 about a vertical axis, Z, through the center of gravity
of the golf club head.
[0017] The body may be composed of a plurality of layers of plies
of pre-preg material. The weight strip may be juxtaposed between
layers of the plurality of layers of plies of pre-preg
material.
[0018] Another aspect of the present invention is a golf club head
including a body and a plurality of weight strips. The body has a
hollow interior and is composed of a composite material. The body
has a face, a sole, a crown, a ribbon juxtaposed by the sole and
the crown, a heel end and a toe end. Each of the plurality of
weight strips is composed of a material having a density greater
than the composite material, and each of the plurality of weight
strips is disposed in the ribbon and or the sole. The body has a
volume greater than 300 cm.sup.3, a moment of inertia, Izz, about a
vertical axis, Z, through the center of gravity of the golf club
head that ranges from 3000 g-cm .sup.2 to 5000 g-cm.sup.2, and a
moment of inertia, Iyy, about a horizontal axis, Y, through the
center of gravity of the golf club head that ranges from 1900
g-cm.sup.2 to 2050 g-cm.sup.2.
[0019] Having briefly described the present invention, the above
and further objects, features and advantages thereof will be
recognized by those skilled in the pertinent art from the following
detailed description of the invention when taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0020] FIG. 1 is a top plan view of a golf club head of the present
invention.
[0021] FIG. 2 is a rear view of the golf club head of FIG. 1.
[0022] FIG. 3 is a toe end view of the golf club head of FIG.
1.
[0023] FIG. 4 is a heel end view of the golf club head of FIG.
1.
[0024] FIG. 5 is a cross-sectional view of the golf club head of
FIG. 1 along line 5-5.
[0025] FIG. 6 is a cross-sectional view of the golf club head of
FIG. 1 along line 6-6.
[0026] FIG. 7 is a cross-sectional view of the golf club head of
FIG. 1 along line 7-7.
[0027] FIG. 8 is a cross-sectional view of the golf club head of
FIG. 1 along line 8-8.
[0028] FIG. 8A is a cross-sectional view of the golf club head of
an alternative embodiment with a sole plate having a an attached
hosel.
[0029] FIG. 9 is an exploded view of the golf club head of the
present invention.
[0030] FIG. 9A is an exploded view of an alternative embodiment of
the golf club head of the present invention
[0031] FIG. 9B is an exploded view of another alternative
embodiment of the golf club head of the present invention.
[0032] FIG. 9C is an exploded view of yet another alternative
embodiment of the golf club head of the present invention.
[0033] FIG. 10 is a top plan view of a golf club of the present
invention illustrating the Y axis and X axis.
[0034] FIG. 10A is a heel side plan view of a golf club of the
present invention illustrating the Z axis and X axis.
[0035] FIG. 10B is a front plan view of a golf club of the present
invention illustrating the Z axis and Y axis.
[0036] FIG. 11 is a front plan view of a golf club of the present
invention illustrating the test frame coordinates X.sup.T and
Y.sup.T and transformed head frame coordinates Y.sup.H and
Z.sup.H.
[0037] FIG. 11A is a toe end view of the golf club of the present
invention illustrating the test frame coordinate Z.sup.T and
transformed head frame coordinates X.sup.H and Z.sup.H.
[0038] FIG. 12 is an illustration of a center of gravity table for
a golf club head of the present invention used to measure the
center of gravity along the X axis.
[0039] FIG. 12A is an illustration of a center of gravity table for
a golf club head of the present invention used to measure the
center of gravity along the Y axis.
[0040] FIG. 12B is an illustration of a center of gravity table for
a golf club head of the present invention used to measure the
center of gravity along the Z axis.
[0041] FIG. 12C is an Inertia Dynamic Moment of Inertia Machine for
a golf club head of the present invention and illustrates distance
from the head to spin axis in the X.sup.T direction.
[0042] FIG. 12D is an Inertia Dynamic Moment of Inertia Machine for
a golf club head of the present invention and illustrates distance
from the head to the spin axis in the Y.sup.T direction.
[0043] FIG. 12E is an Inertia Dynamic Moment of Inertia Machine for
a golf club head of the present invention and illustrates distance
from the head to the spin axis in the Z.sup.T direction.
[0044] FIG. 13 is an illustration of a de-lofting force from a
low-center strike of a golf ball against the striking plate a golf
club of the present invention.
[0045] FIG. 14 is an illustration of a de-lofting moment about the
Y axis through the center of gravity from a low-center strike of a
golf ball against the striking plate a golf club of the present
invention.
[0046] FIG. 15 is an illustration of a de-lofting rotation about
the Y axis through the center of gravity from a low-center strike
of a golf ball against the striking plate a golf club of the
present invention, and the back spin produced on the golf ball.
[0047] FIG. 16 is an illustration of a lofting force from a
high-center strike of a golf ball against the striking plate a golf
club of the present invention.
[0048] FIG. 17 is an illustration of a lofting moment about the Y
axis through the center of gravity from a high-center strike of a
golf ball against the striking plate a golf club of the present
invention.
[0049] FIG. 18 is an illustration of a lofting rotation about the Y
axis through the center of gravity from a high-center strike of a
golf ball against the striking plate a golf club of the present
invention, and the high spin produced on the golf ball.
[0050] FIG. 19 is an illustration of an opening force from
center-toe strike of a golf ball against the striking plate a golf
club of the present invention.
[0051] FIG. 20 is an illustration of an opening moment about the Z
axis through the center of gravity from a center-toe strike of a
golf ball against the striking plate a golf club of the present
invention.
[0052] FIG. 21 is an illustration of an opening rotation about the
Z axis through the center of gravity from a low-center strike of a
golf ball against the striking plate a golf club of the present
invention, and the draw spin produced on the golf ball.
[0053] FIG. 22 is an illustration of a closing force from
center-heel strike of a golf ball against the striking plate of a
golf club of the present invention.
[0054] FIG. 23 is an illustration of a closing moment about the Z
axis through the center of gravity from a center-heel strike of a
golf ball against the striking plate of a golf club of the present
invention.
[0055] FIG. 24 is an illustration of a closing rotation about the Z
axis through the center of gravity from a low-center strike of a
golf ball against the striking plate a golf club of the present
invention, and the slice spin produced on the golf ball.
[0056] FIG. 25 is an illustration of some possible dispersions of
golf balls hit by a golf club of the present invention.
[0057] FIG. 26 is a graph of distance versus increased moment of
inertia, Izz.
[0058] FIG. 27 is a schematic drawing of a face of a golf club head
with the change in distance at nine different hit locations per 100
g-cm.sup.2 increase in the moment of inertia, Izz.
[0059] FIG. 28 is a graph of lateral apex versus increased moment
of inertia, Izz.
[0060] FIG. 29 is a schematic drawing of a face of a golf club head
with the change in lateral apex at nine different hit locations per
100 g-cm.sup.2 increase in the moment of inertia, Izz.
[0061] FIG. 30 is a graph of distance versus increased moment of
inertia, Iyy.
[0062] FIG. 31 is a schematic drawing of a face of a golf club head
with the change in distance at nine different hit locations per 100
g-cm.sup.2 increase in the moment of inertia, Iyy.
[0063] FIG. 32 is a graph of change in dispersion versus change in
club head speed for various club heads with varying moments of
inertia, Izz.
DETAILED DESCRIPTION
[0064] As shown in FIGS. 1-4, a golf club head of the present
invention is generally designated 20. The club head 20 may be a
fairway wood or a driver. The club head 20 has a body 22 that is
generally composed of a composite material such as plies of carbon
pre-preg (pre-impregnated) sheets, or a similar non-metallic
material. The body 22 has a crown 24, a face 26, a sole 28 and a
ribbon 30 juxtaposed by the sole 28 and the crown 24. The ribbon 30
generally extends from a toe end 32 to a heel end 34. The ribbon 30
generally begins at one end of the face 26 and ends at an opposite
end of the face 26. A rear 36 of the body 22 is opposite the face
26 and is defined by portions of the ribbon 30, the crown 24 and
the sole 28. The ribbon 30 increases the volume of the club head 20
and also assists in creating a club head 20 with a higher moment of
inertia as described in greater detail below. Also, at the heel end
34 of the club head 20 is a hosel 38 with a shaft opening 39 for
insertion of a shaft therein.
[0065] As shown in FIGS. 5-8, the club head 20 has a weight strip
40 disposed in the ribbon 30 of the club head 20. The weight strip
40 is preferably embedded within layers of the plies of pre-peg
41a-b as described in greater detail below. A sole plate 42 is
attached to the sole 28 of the body 22.
[0066] As shown in FIG. 8, the sole plate 42 is attached to the
exterior surface of the sole 28 and a hosel 38 is positioned within
the hollow interior 44 of the club head 20. The sole plate is
preferably composed of a metal such as aluminum, titanium or
stainless steel. The sole plate 42 weighs approximately 5 grams to
15 grams. The hosel 38 is preferably composed of a metal such as
stainless steel. The hosel 38 preferably weighs 12 to 16 grams.
[0067] As shown in FIG. 8A, sole plate 42 may be integral with the
hosel 38 forming a sole plate hosel integral piece 43 that is
incorporated into the club head 20. The hosel 38 lies within the
hollow interior 44 of the club head 20. Preferably, the club head
20 has a hollow interior 44, however, the light weight of the
composite body 22 allows for numerous manipulations in placement of
weight, foam, sound enhancing devices and the like within the
hollow interior 44.
[0068] As shown in FIG. 9, the sole plate hosel integral piece 43
is inserted into a sole cavity that is shaped to accommodate the
sole plate 42. The hosel 38 is inserted through a hosel aperture 50
to connect with the shaft opening 39 for placement of a shaft
therethrough. A sole plate aperture 52 allows for access to the
hollow interior 44 through the sole 28 which is utilized for
fabrication of club head 20 as described below. In one embodiment,
the sole plate hosel integral piece 43 is composed of a stainless
steel material. The sole plate hosel integral piece 43 is further
described in U.S. Pat. No. 6,332,847, filed on Dec. 29, 1999, and
entitled Integral Sole Plate And Hosel For A Golf Club Head, which
is hereby incorporated in its entirety.
[0069] The weight strips 40 are preferably composed of a film
loaded with a high density metal (like tungsten), or a metal
material such as copper, tungsten, steel, aluminum, tin, silver,
gold, platinum, or the like. A preferred weight strip 40 is a
thermoplastic material filled with a metal to an appropriate
density, and the metal filler may be tungsten, brass, copper,
steel, tin, or the like. The weight strip 40 has a density greater
than the composite material of the body 22. Each weight strip 40
individually weighs approximately 3 grams to 35 grams, and more
preferably from 10 grams to 30 grams. The total combined weight of
all of the weight strips 40 is approximately 50 grams to 70 grams,
and most preferably 60 grams.
[0070] Preferably, the weight strip 40 extends from approximately
the heel end 34 of the face 26 through the rear 36 to the toe end
32 of the face 26. However, the weight strip 40 may only extend
along the rear 36 of the ribbon 30, the heel end 34 of the ribbon
30, the toe end 32 of the ribbon 30, or any combination thereof.
Preferably, the weight strip 40 occupies the majority of area of
the ribbon 30. However, the weight strip 40 may only occupy a small
area of the ribbon 30.
[0071] In preferred embodiment, the weight strip 40 is a single
piece co-cured to the ribbon 30. However, the weight strip 40 may
be two, three, four, or more pieces co-cured to the ribbon and
extending along a portion of the ribbon 30. The multiple piece
weight strip 40 may be partitioned horizontally or vertically. For
example, as shown in FIG. 9A, three separate weight strips 40a-c
are positioned in the toe end 32 of the ribbon 30, the rear 36 of
the ribbon 30, and the heel end 32 of the ribbon 30.
[0072] In an alternative embodiment as shown in FIG. 9B, three
separate weight strips 40a-c are parallel to each other and extend
along substantially the entire length of the ribbon 30. In yet
another alternative embodiment shown in FIG. 9C, multiple weight
strips 40a-j are evenly distributed along the entire length of the
ribbon 30. Those skilled in the pertinent art will recognize that
numerous variations for the weight strip 40 are possible without
departing from the scope and spirit of the present invention.
[0073] As previously stated, the preferred composite material is
plies of carbon pre-preg sheets. Plies of pre-preg composite sheets
are manufactured by pulling strands of fiber in a parallel motion,
preferably carbon or glass fiber, through a resin film and allowing
the resin to partially cure or "stage". When the resin is partially
staged, the resin holds the fibers together such that the fibers
form a malleable sheet with all of the fibers in a specific
orientation relative to an edge of the sheet. Exemplary carbon
pre-preg fiber sheets may be obtained from Newport Composites of
Santa Ana, Calif., Cytec Inc. of Anaheim, Calif., or Hexcel Inc. of
Pleasonton, Calif. Alternatively, the layers 41a-c of the composite
body 22 may comprise a plurality of plies of composite fiber
without any resin, each typically comprising a continuous fiber
braid or mat, that are used to make a dry reinforcement preform, as
described in U.S. Pat. No. 6,010,411 filed on Oct. 23, 1997, which
is hereby incorporated by reference in its entirety.
[0074] The composite body 22 may include one or more plies of
pre-preg that define structurally the various walls of the golf
club head 20. Stated differently, the plies of pre-preg composite
sheet are selected and included in the various walls of the golf
club head 20 based upon the structural characteristics desired for
a finished golf club head. As will be understood by those skilled
in the art, the simplified arrangement of plies shown in the
figures is merely demonstrative of one configuration that a
designer might select. Numerous other configurations may, of
course, be utilized depending upon the desired structural
characteristics of the golf club head 20. One such configuration is
set forth in U.S. Pat. No. 6,386,990, filed on Dec. 29, 1999,
entitled Composite Golf Club Head And Manufacturing Method, which
is hereby incorporated by reference in its entirety.
[0075] FIGS. 10, 10A and 10B illustrate the axes of inertia through
the center of gravity of the golf club head. The axes of inertia
are designated X, Y and Z. The X axis extends from the striking
plate 26 through the center of gravity, CG, and to the rear of the
golf club head 20. The Y axis extends from the toe end 32 of the
golf club head 20 through the center of gravity, CG, and to the
heel end 34 of the golf club head 20. The Z axis extends from the
crown 24 through the center of gravity, CG, and to the sole 28.
[0076] As defined in Golf Club Design, Fitting, Alteration &
Repair, 4.sup.th Edition, by Ralph Maltby, the center of gravity,
or center of mass, of the golf club head is a point inside of the
club head determined by the vertical intersection of two or more
points where the club head balances when suspended. A more thorough
explanation of this definition of the center of gravity is provided
in Golf Club Design, Fitting, Alteration & Repair. The center
of gravity and the moment of inertia of a golf club head 20 are
preferably measured using a test frame (X.sup.T, Y.sup.T, Z.sup.T),
and then transformed to a head frame (X.sup.H, Y.sup.H, Z.sup.H),
as shown in FIGS. 11 and 11A. The center of gravity of a golf club
head may be obtained using a center of gravity table 55 having two
weight scales thereon, as shown in FIGS. 12, 12A and 12B. If a
shaft is present, it is removed and replaced with a hosel cube 57
that has a multitude of faces normal to the axes of the golf club
head 20. Given the weight of the golf club head 20, the scales
allow one to determine the weight distribution of the golf club
head when the golf club head is placed on both scales
simultaneously and weighed along a particular direction, the X, Y
or Z direction. The weight scales are parallel to the earth's
gravity allowing the weight distribution along each direction to be
calculated to determine the location of the center of gravity
where:
[0077] W.sub.AO, W.sub.BO: Weight without head (fixture)
[0078] and
[0079] W.sub.AH, W.sub.BH: Weight with head
[0080] The X axis location is determined using the following
equations: 1 M A = 0 = ( W B H - W B O ) l - r W r = ( W B H - W B
O ) W l c o n s t r a i nt : l 2 + d 1 = r + X c g T + s + d 2 X c
g T - = ( W B H - W B O ) w l + S + d 2 - l 2 - d 1
[0081] The Y axis location is determined using the following
equations: 2 M A = 0 = ( W B H - W B O ) l - r W r = ( W B H - W B
O ) W l C o n s t r a i nt : l 2 + d 1 = r + Y c g T Y c g T = - (
W B H - W B O ) w l + l 2 + d 1
[0082] The Z axis location is determined using the following
equations: 3 M A = o _ = ( W B H - W B O ) l - r W r = ( W B H - W
B O ) W l C o n s t r a i nt : l 2 + d 1 = r + Z c g T - Z c g T =
- ( W B H - W B O ) W l - l 2 - d 1
[0083] Once the test frame coordinates are determined, they are
transformed to head frame coordinates using the following
equations: 4 X c g H = - Z c g T Y c g H = - X c g cos ( lie ) + Y
c g sin ( lie ) - d x / tan ( lie ) Z c g H = - X c g sin ( lie ) +
Y c g cos ( lie ) + d z o r : { X c g H Y c g H Z c g H } = ( 0 0 -
1 - cos ( lie ) sin ( lie ) 0 sin ( lie ) cos ( lie ) 0 ) { X c g T
Y c g T Z c g T } + z { 0 - 1 / tan ( lie ) 1 }
[0084] The moment of inertia is measured using an Inertia Dynamic
Moment of Inertia machine 59 as shown in FIGS. 12C, 12D and 12E.
The machine 59 has a rectangular plate with adapter holes spaced
0.5 inch apart from each other. The rectangular plate is mounted on
the machine 59 to allow oscillation thereof. A golf club head 20 is
placed on the rectangular plate and the time for one oscillation
period is measured by the machine. The oscillation time is directly
related to the moment of inertia of the golf club head about the
axis of rotation of the machine, which in effect is a single degree
of freedom with the restoring force generated by a torsional
spring. By changing the orientation of how the golf club head is
mounted on the plate, the desired moment of inertia may be measured
for an axis. Nine different orientations are required to generate
an inertia tensor, and since the moment of inertia measured
includes the plate and the adapter, nine additional measurements
are required to measure the baseline moment of inertia of the
initial setup. The moment of inertia of the golf club head is the
difference between the measurement taken with the golf club head,
adapter and plate and the internal rotating mass of the machine,
and that of the just the adapter and plate and the internal
rotating mass of the machine. For the nine measurements done with
the golf club head, the orientations are the same from head to
head, the position on the rectangular plate depends on the center
of gravity of the particular golf club head. The nine measurements
without the golf club head are the same for orientation and the
location of the adapter. The machine has a center of gravity and
moment of inertia program to calculate the adapter holes on the
rectangular plate that place the center of gravity closest to the
axis of rotation, thereby minimizing error. The program uses the
parallel axis theorem to account for the axis of rotation not
containing the center of gravity of the golf club head. This will
yield an inertia tensor about the center of gravity, which in turn
allows the moment of inertia about any axis to be calculated for
the golf club head.
1 MASS CG (in) Inertia (gm-cm.sup.2) CLUB (gm) X Y Z Ixx Iyy Izz
Ixy Ixz Iyz Crane Japan 1 193.9 0.433 0.944 0.933 1,700.13 1,044.17
2,150.47 162.12 3.21 -47.49 Composite Driver Diawa 1, G-3 186.5
0.707 0.746 0.87 1,248.07 1,298.21 1,951.54 89.81 -94.2 -1.18
Composite Driver Pro Spirit 11.degree. 198.7 0.433 0.944 0.933
1,480.37 1,073.10 1,985.16 143.86 -81.3 55.2 Composite Driver Zett
10.degree. Composite 208.8 0.322 0.547 1.227 1,989.14 1,166.16
2,155.67 197.83 -62.3 -151.5 Driver EDO 10.degree. Composite 204.4
0.656 1.208 0.825 2,011.04 1,139.42 2,166.16 280.19 -90 -282.1
Driver Yonex 1 ADX 100i 200 0.602 1.037 0.844 1,631.59 1,161.33
2,052.75 104.05 -41.2 33.45 Composite Driver Yonex 1 Aerona 300
202.9 0.494 0.624 0.919 1,876.79 1,155.33 2,435.72 205.06 -92.6
21.88 Composite Driver
[0085] Table One lists the location of the center of gravity and
moment of inertia about the center of gravity for competitor
composite golf club heads. The moment of inertia Izz about the Z
axis is less than 2436.00 g-cm.sub.2 for any of the competitor
composite heads. The highest moment of inertia, Izz, about the Z
axis is 2435.72 g-cm.sup.2 for the Yonex 1 AERONA 300 composite
driver. The moment of inertia, Iyy, about the Y axis is less than
1300.00 g-cm.sup.2 for any of the competitor composite heads. The
highest moment of inertia, Iyy, about the Y axis is 1298.21
g-cm.sup.2 for the Daiwa 1, G3 composite driver. The mass for all
of the competitor composite heads ranges from 186 grams to 208.5
grams.
2TABLE Two Head Weighting Ixx Iyy Izz Ixy Ixz Iyz Pre-Ex. 1 Shell
only 1242 888 1461 79 77 140 Ex. 1 Weighted 2797 2183 3824 256 273
493 Pre-Ex. 2 Shell only 1442 978 1635 60 78 153 Ex. 2 Weighted
2904 2076 3857 194 242 437 Pre-Ex. 3 Shell only 1403 943 1602 63 72
165 Ex. 3 Weighted 2716 2078 3760 262 173 394
[0086] Table Two lists the moment of inertia for golf club heads 20
of the present invention. The shell is the golf club head without
the weight(s) 40. The unweighted club head 20 weighs from 90 grams
to 120 grams thereby allowing for 60 grams to 105 grams of weight
to be placed accordingly to achieve the high moment of inertia for
the golf club head 20 of the present invention. The moment of
inertia, Izz, about the Z axis for the golf club head 20 of the
present invention will range from 2800 g-cm.sup.2 to 500
g-cm.sup.2, preferably from 3000 g-cm.sup.2 to 4500 g-cm.sup.2, and
most preferably from 3500 g-cm.sup.2 to 4000 g-cm.sup.2 . The
moment of inertia, Iyy, about the Y axis for the golf club head 20
of the present invention will range from 1500 g-cm.sup.2 to 2500
g-cm.sup.2, preferably from 1800 g-cm.sup.2 to 2100 g-cm.sup.2, and
most preferably from 1900 g-cm.sup.2 to 2050 g-cm.sup.2.
3 TABLE Three Delta from Total Distance (yds) center distance (yds)
Head Izz Heel Center Toe Heel Toe Center Ex. 2 3850 219.6 229.8
222.5 10.2 7.3 17.5 Cmp. 1 2860 231.8 239.5 224.2 7.7 15.3 23 Cmp.
2 2900 231 243.8 227.8 12.8 16 28.8
[0087] Table Three demonstrates the distance and dispersion of a
golf club head 20 of the present invention, Ex. 2, versus a 300
cubic centimeter, high COR titanium golf club head, Cmp. 1, and a
350 cubic centimeter, high COR titanium golf club head, Cmp. 2. The
high moment of inertia composite head 20 of the present invention
performs very similar to the titanium golf club heads.
[0088] FIGS. 13-18 illustrate the effects of increasing the moment
of inertia, Iyy, about the Y axis for high center hits and low
center hits. High center hits are defined as hits that have their
impulse vector above the center of gravity of the golf club head
20, and low center hits are defined as hits that have their impulse
vector below the center of gravity of the golf club head 20. For
low center hits, as shown in FIGS. 13-15, the increased Iyy moment
of inertia causes the golf club head 20 to rotate less in a
de-lofting manner which increases the launch angle and decreases
the back spin of the golf ball 63. For high center hits, as shown
in FIGS. 16-18, the increased Iyy moment of inertia causes the golf
club head 20 to rotate in a lofting manner which increases the
launch angle and reduces the back spin of the golf ball 63.
[0089] Every 100 gram-centimeter squared (g-cm.sup.2) increase in
the moment of inertia Iyy about the Y axis should result in a 1.0
yard increase in total distance for high center hits, and a 1.10
yard increase in total distance for a low center hit. The total
dispersion is increased 1.20 feet for a high center hit for every
100 g-cm.sup.2 increase in the moment of inertia, Iyy, and it is
decreased 0.10 feet for a low center hit for every 100 g-cm.sup.2
increase in the moment of inertia, Iyy. However, excessive changes
in the launch conditions may result in less desirable trajectory
and reduced distance. Further, energy of the golf club head 20 that
would have been transferred to the golf ball 63, that could
contribute to increased golf ball speed and distance, is lost in
the rotation of the golf club head 20. In general, a larger moment
of inertia about the center of gravity should stabilize the golf
club head, and hence provide more consistent launch conditions
between high center shots and low center shots.
[0090] FIGS. 19-24 illustrate the effects of increasing the moment
of inertia Izz about the Z axis for toe-ward or heel-ward hits. A
toe-ward hit is defined as a hit that is off-center from the center
of gravity toward the toe. A heel ward hit is defined as a hit that
is off-center from the center of gravity toward the heel. For toe
ward hits, as shown in FIGS. 19-21, the increased moment of inertia
Izz causes the golf club head 20 to rotate in an opening manner
which increases the side angle to the right and increases the draw
spin of the golf ball 63. For heel ward hits, as shown in FIGS.
22-24, the increased moment of inertia, Izz, causes the golf club
head 20 to rotate in a closing manner which increases the side
angle to the left and increases the fade spin of the golf ball
63.
[0091] Every 100 g-cm.sup.2 increase in the moment of inertia, Izz,
about the Z axis should result in a 0.9 yard increase in total
distance for toe ward hits, and a 0.7 yard increase in total
distance for a heel ward hit. The total dispersion is increased 4.9
feet for a heel ward hit for every 100 g-cm.sup.2 increase in the
moment of inertia, Izz, about the Z axis, and it is decreased 4.7
feet for a toe ward hit for every 100 g-cm.sup.2 increase in the
moment of inertia, Izz, about the Z axis. However, as mentioned
previously, excessive changes in the launch conditions may result
in less desirable trajectory and reduced distance. Further, energy
of the golf club head 20 that would have been transferred to the
golf ball 63, that could contribute to increased golf ball speed
and distance, is lost in the rotation of the golf club head 20.
[0092] As shown in FIG. 25, the increased moment of inertia, Izz,
about the Z axis will result in a preferred ball flight. Increasing
the moment of inertia, Izz, about the Z axis does not necessarily
improve the relative dispersion pattern, RD, of multiple hits at
various locations on the striking plate of the golf club head 20.
However, toe ward and heel ward hits have a reduced degree of
lateral travel, LT, for multiple hits. Overall dispersion of
multiple hits is a function of several parameters such as center of
gravity, bulge radius and the coefficient of restitution of the
golf club head for a given head speed.
[0093] FIG. 26 is a graph showing that the overall average distance
(nine hit positions) for a 100 MPH swing speed will increase as the
moment of inertia, Izz, increases for a golf club head. FIG. 27
illustrates the increase in distance at each of the nine hit
positions of a face per 100 g-cm.sup.2 increase in the moment of
inertia, Izz, for a golf club head.
[0094] FIG. 28 is a graph showing that the average lateral apex
(nine hit positions) for a 100 MPH swing speed will decrease as the
moment of inertia, Izz, increases for a golf club head. The lateral
apex is the bend of the shot in flight from the impact position to
the final flight position (not the final roll position). FIG. 29
illustrates the decrease in the lateral apex at each of the nine
hit positions of a face per 100 g-cm.sup.2 increase in the moment
of inertia, Izz, for a golf club head.
[0095] FIG. 30 is a graph showing that the overall average distance
(nine hit positions) for a 100 MPH swing speed will increase as the
moment of inertia, Iyy, increases for a golf club head. FIG. 31
illustrates the increase in distance at each of the nine hit
positions of a face per 100 g-cm.sup.2 increase in the moment of
inertia, Iyy, for a golf club head.
[0096] FIG. 32 is a graph of the change in dispersion versus the
change in head speed for club heads with varying moments of
inertia, Izz. As shown in FIG. 32, the change in dispersion is
reduced as the moment of inertia, Izz, is increased for a golf club
head.
[0097] FIG. 33 is a graph of the change in dispersion versus the
change in bulge radius of a face for club heads with varying
moments of inertia, Izz. As shown in FIG. 33, the change in
dispersion is reduced as the moment of inertia, Izz, is increased
for a golf club head.
[0098] From the foregoing it is believed that those skilled in the
pertinent art will recognize the meritorious advancement of this
invention and will readily understand that while the present
invention has been described in association with a preferred
embodiment thereof, and other embodiments illustrated in the
accompanying drawings, numerous changes, modifications and
substitutions of equivalents may be made therein without departing
from the spirit and scope of this invention which is intended to be
unlimited by the foregoing except as may appear in the following
appended claims. Therefore, the embodiments of the invention in
which an exclusive property or privilege is claimed are defined in
the following appended claims.
* * * * *
References