U.S. patent application number 10/334896 was filed with the patent office on 2003-07-31 for golf club head.
Invention is credited to Kato, Masayuki, Setokawa, Hiroto.
Application Number | 20030144078 10/334896 |
Document ID | / |
Family ID | 27606222 |
Filed Date | 2003-07-31 |
United States Patent
Application |
20030144078 |
Kind Code |
A1 |
Setokawa, Hiroto ; et
al. |
July 31, 2003 |
Golf club head
Abstract
A golf club head comprises a face portion defining a clubface
for striking a golf ball; the face portion provided in the clubface
with a high-resilience part made of a metal material having a
Young's modulus E of not less than 29 (GPa) but not more than 107
(GPa); and in a measuring state of the club head which is defined
as being placed on a horizontal plane such that a clubshaft center
line inclines at its lie angle within a vertical plane and the
clubface inclines at its face angle with respect to the vertical
plane, a moment of inertia of the club head around a horizontal
axis passing a gravity point of the club head in parallel with the
vertical plane, being not less than 1600 (g.multidot.sq.cm) but not
more than 4000 (g.multidot.sq.cm).
Inventors: |
Setokawa, Hiroto; (Kobe-shi,
JP) ; Kato, Masayuki; (Kobe-shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
27606222 |
Appl. No.: |
10/334896 |
Filed: |
January 2, 2003 |
Current U.S.
Class: |
473/345 ;
473/349 |
Current CPC
Class: |
A63B 53/0408 20200801;
A63B 2209/00 20130101; A63B 53/0466 20130101; A63B 53/0416
20200801 |
Class at
Publication: |
473/345 ;
473/349 |
International
Class: |
A63B 053/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2002 |
JP |
2002-18833 |
Claims
1. A golf club head comprising a face portion defining a clubface
for striking a golf ball, the face portion provided in the clubface
with a high-resilience part made of a metal material having a
Young's modulus E of not less than 29 (GPa) but not more than 107
(GPa), in a measuring state of the club head which is defined as
being placed on a horizontal plane such that a clubshaft center
line inclines at its lie angle within a vertical plane and the
clubface inclines at its face angle with respect to the vertical
plane, a moment of inertia of the club head around a horizontal
axis passing a gravity point of the club head in parallel with the
vertical plane, being not less than 1600 (g.multidot.sq.cm) but not
more than 4000 (g.multidot.sq.cm).
2. A golf club head according to claim 1, wherein the product
(t.multidot.E) of the Young's modulus E (GPa) and a thickness t
(mm) of the high-resilience part is not less than 77
(GPa.multidot.mm) but not more than 245 (GPa.multidot.mm).
3. A golf club head according to claim 1 or 2, wherein in the
measure state, a gravity point distance which is defined as the
shortest distance between the clubshaft center line and a projected
point of the gravity point on the vertical plane, is not less than
26 mm bot not more than 40 mm.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a golf club head being
capable of increasing the carry.
[0002] The laid-open international application WO98/46312 discloses
a golf club head, wherein in order to increase the traveling
distance of struck golf balls, a metal material having a relatively
low Young's modulus is used in the face portion according to the
so-called impedance matching theory. In this theory, the mechanical
impedance of the clubface is lowered to near that of the golf balls
in the expectation that the loss of the impact energy which
transfers from the club head to the hit ball is minimized and as a
result the initial speed of the hit ball is increased.
[0003] When a golf ball is hit at a sweet spot of the clubface, the
traveling distance (carry and run) effectively increases. However,
if the hitting point is off the sweet spot towards the crown or
sole, there is a tendency for the carry loss to become considerably
large contrary to expectation.
[0004] FIG. 8 shows results of an experiment in which several kinds
of club heads were made changing the Young's modulus of the face
portion, and the backspin of the hit ball was measured by hitting
the golf ball at the sweet spot and also an upper point and a lower
point at a distance of 10 mm from the sweet spot towards the crown
and the sole, respectively. As shown in this graph, as the Young's
modulus of the face portion is decreased, backspin increases at an
accelerating pace in case of the lower hitting, but in case of the
upper hitting backspin decreases at an accelerating pace. Thus, in
this kind of club head having a low Young's modulus in the
clubface, a vertical gear effect appears strongly than the club
heads having normal Young's modulus. Here, the vertical gear effect
is the following phenomenon. When a golf ball is struck off the
sweet spot SS as shown in FIG. 9, a moment of rotation whose
magnitude is substantially equal to the product of the impact force
F and distance L1, L2 is produced on the club head (a) around its
gravity point G, and the club head rotates around a horizontal axis
passing the gravity point G by a minute angle in a moment. As a
result, the struck ball (b) receives a force in the opposite
direction to the rotational direction of the club head (a).
[0005] Thus, in case of lower hitting, the backspin is excessively
increased and the trajectory becomes high to increase the carry
loss.
SUMMARY OF THE INVENTION
[0006] It is therefore, an object of the present invention to
provide a golf club head, in which a vertical gear effect is
effectively controlled to increase the carry although the Young's
modulus of the face portion is low.
[0007] According to the present invention, a golf club head
comprises
[0008] a face portion defining a clubface for striking a golf
ball,
[0009] the face portion provided in the clubface with a
high-resilience part made of a metal material having a Young's
modulus E of not less than 29 (GPa) but not more than 107
(GPa),
[0010] in a measuring state of the club head which is defined as
being placed on a horizontal plane such that a clubshaft center
line inclines at its lie angle within a vertical plane and the
clubface inclines at its face angle with respect to the vertical
plane, a moment of inertia of the club head around a horizontal
axis passing a gravity point of the club head in parallel with the
vertical plane, being not less than 1600 (g.multidot.sq.cm) but not
more than 4000 (g.multidot.sq.cm).
[0011]
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a golf club head according
to the present invention.
[0013] FIG. 2 is a front view thereof.
[0014] FIG. 3 is a top view thereof.
[0015] FIG. 4 is a sectional view thereof taken along vertical
plane VP2 shown in FIG. 3.
[0016] FIG. 5 is a sectional view thereof taken along a line A-A
shown in FIG. 3.
[0017] FIG. 6 is an exploded perspective view thereof.
[0018] FIGS. 7a and 7b are schematic overhead views for explaining
insufficient return and full return of the clubface at the time of
striking a golf ball.
[0019] FIG. 8 is a graph showing a relationship between the
backspin and hitting position as a function of the Young's
modulus.
[0020] FIG. 9 is a cross sectional view of a club head for
explaining the vertical gear effect.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0021] Embodiment of the present invention will now be described in
detail in conjunction with the accompanying drawings.
[0022] In the drawings, golf club head 1 according to the present
invention is a wood-type golf club head for number 1 driver.
[0023] The club head 1 comprises a face portion 3 defining a
clubface 2 for striking a golf ball, a crown portion 4 defining a
top face of the club head intersecting the clubface 2 at the upper
edge 2a thereof, a sole portion 5 defining a bottom face of the
club head intersecting the clubface 2 at the lower edge 2b thereof,
a side portion 6 between the crown portion 4 and sole portion 5,
which extends from the toe-side edge 2t to the heel-side edge 2e of
the clubface 2 through the back of the club head, and a hosel
portion 7 provided with a clubshaft-inserting hole 7a.
[0024] The clubshaft-inserting hole 7a has an opening for the
clubshaft (not shown) at the top, and extends to the inside of the
clubhead as shown in FIG. 5. The center line CL (hereinafter the
"clubshaft center line CL") is used to determine the undermentioned
various positions and orientation of the club head. The
clubshaft-inserting hole 7a in this example is circular and
terminated in the cavity (i).
[0025] In FIGS. 1-5, the club head 1 is in its measuring state. The
measuring state is such that, as shown in FIG. 2 and FIG. 3, the
club head 1 is placed on a horizontal plane HP, so that the
clubshaft center line CL inclines at its lie angle .beta. within a
vertical plane VP1, and the clubface 2 inclines at its face angle
.beta. with respect to the vertical plane VP1. Here, the face angle
.beta. is the angle between the vertical plane VP1 and a horizontal
tangential line N to the centroid or center of FIG. 2c of the
clubface 2.
[0026] In this embodiment, as shown in FIG. 6, the club head 1 is
made up of a main body 1A having an opening O on the front thereof,
and a face member 1B which is fixed on the front of the head main
body 1A so that the opening O is closed and the closed cavity (i)
is formed. Thus, behind the face portion 3, a hollow is formed.
[0027] The head main body 1A in this example comprises the crown
portion 4, sole portion 5, side portion 6, hosel portion 7 and an
annular periphery part 9 of the face portion 3 of which inner edge
defines the above-mentioned opening O.
[0028] As to the material of the head main body 1A, metal materials
such as aluminum alloys, pure titanium, titanium alloys, and
stainless steel can be used. Preferably a titanium alloy whose
specific tensile strength is high is used. In this example, the
head main body 1A is made of a titanium alloy Ti-6Al-4V through a
lost-wax precision casting process. Aside from metal materials,
fiber reinforced resins or plastics may be used too.
[0029] The face member 1B in this example is a slightly curved
plate of which front surface defines almost entirety of the
clubface 2 because the above-mentioned annular periphery part 9 is
very narrow in width. The face member 1B is fitted in the opening O
and fixed by an appropriate way such as adhesive agent, welding,
caulking and press fitting.
[0030] AS shown in FIG. 4, the back face 11 of the face member 1B
is supported by a ledge 9a provided on the head main body 1A along
the inner edge of the periphery part 9. The back-supported area is
preferably set in a range of from 2 to 20%, preferably 2 to 10%,
more preferably 2 to 5% of the overall area s of the clubface 2.
The ledge 9a in this example is continuously formed along the inner
edge, but it can be formed at intervals. Instead of the continuous
or discontinuous ledge 9a supporting the periphery of the back face
11, a support for the entirety of the back face 11 may be provided.
Further, it may be possible to omit such back support.
[0031] In this embodiment, a high-resilience part 8 is formed in
the face portion 3 by the face member 1B.
[0032] The high-resilience part 8 has a Young's modulus E which is
not less than 29 GPa, preferably not less than 39 GPa, more
preferably not less than 49 GPa, still more preferably not less
than 58 GPa, but not more than 107 GPa, preferably not more than 98
GPa, more preferably not more than 88 GPa, still more preferably
not more than 78 GPa.
[0033] Thus, the face member 1B is made of a metal material having
such Young's modulus E.
[0034] If the Young's modulus E is increased over 107 GPa, the
impedance of the clubface increases over that of balls, and the
effect to increase the initial velocity of the ball is lessened. If
the Young's modulus E is decreased under 29 GPa, it becomes
difficult to provide durability for the face portion.
[0035] For the metal material of the face member 1B, various alloys
may be used, but amorphous alloys and titanium alloys are
preferably used. AS to the amorphous alloys, for example, zirconium
alloys are preferably used for the workability and the like. On the
other hand, in case of crystalloid alloys, titanium-zirconium
alloys are preferably used.
[0036] The thickness t of the high-resilience part 8 or the face
member 1B in this embodiment is preferably not less than 1.0 mm,
more preferably not less than 1.5 mm, still more preferably not
less than 2.0 mm, but preferably not more than 3.5 mm, more
preferably not more than 3.0 mm, still more preferably not more
than 2.8 mm, yet still more preferably not more than 2.5 mm. If the
thickness t is less than 1.0 mm, the strength and durability are
liable to become insufficient. If the thickness t is more than 3.5
mm, the clubface becomes rigid, and the effect to increase the
carry becomes lessened.
[0037] As to the thickness of the face portion 2 (including the
face member in this embodiment), on the other hand, it is
preferable that the thickness satisfies the above-mentioned
limitation of the thickness t through the entirety of the face
portion 2 if possible.
[0038] Further, it is preferable that the product (t.multidot.E) of
the Young's modulus E (GPa) and the thickness t (mm) is not less
than 77 (GPa.multidot.mm), more preferably not less than 86
(GPa.multidot.mm), still more preferably not less than 96
(GPa.multidot.mm), but not more than 245 (GPa.multidot.mm), more
preferably not more than 231 (GPa.multidot.mm), still more
preferably not more than 221 (GPa.multidot.mm).
[0039] If the product (t.multidot.E) is less than 77
(GPa.multidot.mm), the strength and durability of the clubface are
liable to become insufficient. If more than 245 (GPa.multidot.mm),
the clubface becomes rigid, and the effect to increase the carry
becomes lessened.
[0040] In this example, the thickness t is substantially constant,
but if varied, the area mean value (namely, a value which is
obtained by weighting the thickness with area and then averaging
the weighted thickness, more specifically, a value obtained by
dividing the volume by the area) is used as the thickness t in
calculating the product (t.multidot.E).
[0041] As to the materials of the club head, it is possible that
the entirety of the club head (in this embodiment, both of the main
body 1A and face member 1B) is made of the same metal material
having the above-mentioned Young's modulus.
[0042] Further, the club head 1 has a moment of inertia (I) which
is not less than 1600 (g.multidot.sq.cm), preferably not less than
1800 (g.multidot.sq.cm), more preferably not less than 2000
(g.multidot.sq.cm), still more preferably not less than 2200
(g.multidot.sq.cm), but not more than 4000 (g.multidot.sq.cm),
preferably not more than 3500 (g.multidot.sq.cm), more preferably
not more than 3100 (g.multidot.sq.cm).
[0043] Here, the moment of inertia (I) is that around a horizontal
axis HL which passes through the gravity point G of the club head
in parallel with the above-mentioned vertical plane VP1, and it is
measured including the coating of the head if any, but the
clubshaft, ferrule and the like are not included.
[0044] By setting the moment of inertia (I) in a relatively high
range as above, if hitting a golf ball off the sweet spot SS as
shown in FIG. 9, the rotation of the club head 1 around the
horizontal axis HL is prevented or effectively decreased and the
vertical gear effect can be effectively controlled.
[0045] If the moment of inertia (I) is more than 4000
(g.multidot.sq.cm), the size of the club head is inevitably
increases, and it becomes hard to handle the club.
[0046] The moment of inertia (I) of the club head 1 can be
increased by a) increasing the head volume, b) increasing the wall
thickness of the club head away from the gravity point, c)
increasing the specific gravity of the club head away from the
gravity point, and/or d) decreasing the roll radius of the
clubface.
[0047] From this point of view, it is preferable that the head
volume is not less than 280 cc, more preferably not less than 290
cc, still more preferably not less than 300 cc, but not more than
450 cc, more preferably not more than 420 cc, still more preferably
not more than 400 cc.
[0048] As to the clubface 2, the maximum horizontal width FW
thereof is preferably set in a range of from 85 to 110 mm more
preferably 90 to 106 mm, and the maximum vertical height FH thereof
is preferably set in a range of from 40 to 65 mm more preferably 45
to 60 mm.
[0049] The area of the above-mentioned high-resilience part 8 is
set to be more than 65%, preferably more than 75%, more preferably
more than 85%, still more preferably more than 95% of the area of
the clubface 2.
[0050] The clubface 2 is, as shown in FIG. 3, provided with a bulge
whose radius R1 is in a range of from 254 to 304.8 mm, preferably
279.4 to 292.1 mm. Further, as shown in FIG. 4, the clubface 2 is
provided with a roll whose radius R2 is in a range of from 228.6 to
330.2 mm, preferably 254 to 304.8 mm. Here, the radius R2 is
defined in the above-mentioned measuring state as the radius of
curvature of the clubface 2 at a second vertical plane VP2 which
includes the center 2c of figure of the clubface 2 and is
perpendicular to the vertical plane VP1. By setting the roll radius
R2 as above, the vertical gear effect can be reduced.
[0051] Further, the club head 1 has a gravity point distance c
which is not less than 26 mm, preferably not less than 28 mm, more
preferably not less than 30 mm, but not more than 40 mm, preferably
not more than 38 mm, more preferably not more than 36 mm, still
more preferably not more than 34 mm.
[0052] Here, the gravity point distance c is, as shown in FIG. 3
and FIG. 5, the shortest distance between the clubshaft center line
CL and the projected point Ga of the gravity point G on the
vertical plane VP1 under the measuring state.
[0053] If the gravity point distance C is more then 40 mm, the so
called "return" of the club head 1 is liable to become insufficient
as shown in FIG. 7a when striking the ball.
[0054] Therefore, in case of a golfer who hits right-handed, the
ball is liable to curve to the right.
[0055] If the gravity point distance c is less than 26 mm, a moment
of inertia of the club head around the clubshaft center line
excessively decreases. As a result, unfavorably the carry is
greatly varied depending on the ball hitting point.
[0056] By setting the gravity point distance C as above, the club
head 1 can easily and fully return to the original position
prepared for the stroke as shown in FIG. 7b. As a result, a draw
shot to increase the carry becomes easy even for average
golfers.
[0057] Comparison Test
[0058] Changing the face member material, Young's modulus E,
product (E.times.t), moment of inertia and gravity point distance
as shown in Table 1, several kinds of wood-type golf club heads
having the structure shown in FIGS. 1 to 6 were made. The moment of
inertia and gravity point distance were adjusted by attaching
weight to appropriate part of the inside of the head main body such
as the backside of the side portion, hosel portion, toe and sole
portion. The moment of inertia (I) was measured with a
moment-of-inertia measurement instrument made by Inertia Dynamics,
Inc. The heads were attached to carbon shafts (FLEX R) and 45-inch
drivers were made, and the following tests were conducted.
[0059] Hitting Test 1
[0060] Each club was attached to a swing robot, and three-piece
balls (MAXFLI HI-BRID, Sumitomo Rubber Ind., Ltd.) were struck at a
head speed of 40 m/s five times per each of three hitting positions
in each club to obtain mean values of the respective backspin,
initial velocity and travelling distance (carry and run). Here, the
three hitting positions are a sweet spot of the clubface (sweet
spot hit), an upper position 10 mm upward from the sweet spot
(upper hit), and a lower position 10 mm downward from the sweet
spot (lower hit).
[0061] Hitting Test 2
[0062] Each of ten golfers whose handicaps ranged from 2 to 11
struck balls ten times per club. The distance of the landing
position of the hit ball was measured from the line in the aimed
projectile direction of the golf ball. The measured distance is
indicated in meter in Table 1 as the mean value of the ten persons.
Thus, the smaller value is better and means that the direction
stability is good.
1TABLE 1 Head Ref. 1 Ref. 2 Ref. 3 Ref. 4 Ex. 1 Ex. 2 Ex. 3 Ex. 4
Ex. 5 Ex. 6 Ex. 7 Head volume (cc) 270 270 270 270 270 270 270 270
270 270 270 Face portion Max. width = 94 mm, Max. height = 47 mm,
Bulge radius = 304.8 mm, Roll radius = 304.8 mm Face member
Material *1 A B C D A A A A A B B Young's modulus E (GPa) 69 98 118
196 69 69 69 69 69 98 98 Thickness t (mm) 2.8 2.8 2.8 2.8 2.8 2.8
2.8 2.8 2.8 2.8 2.8 Product (E .times. t) (GPa .multidot. mm) 193.2
274.4 330.4 548.8 193.2 193.2 193.2 193.2 193.2 274.4 274.4 Moment
of inertia I (g .multidot. sq.cm) 1500 1500 1500 1500 2000 3000
3000 3000 3000 2000 2000 Gravity point distance C (mm) 36 36 36 36
36 36 34 32 43 36 32 Back spin (rpm) Upper hit 1621 1706 1726 1720
2013 2115 2111 2113 2009 2121 2123 Sweet spot hit 2612 2733 2741
2763 2544 2659 2661 2662 2543 2603 2610 Lower hit 3624 3434 3359
3307 3026 3011 3002 3006 3030 3013 3001 Initial velocity (m/s)
Upper hit 57.1 56.8 56.2 55.8 57.4 57.7 57.7 57.8 57.7 56.9 58.1
Sweet spot hit 58.7 58.3 57.9 57.4 58.7 58.8 58.7 58.7 58.7 58.4
59.1 Lower hit 57.6 57.1 57 56.4 57.9 58.2 58.3 58.2 58.2 57.2 58
Carry and Run (m) Upper hit 246.3 237.8 235.8 233.1 241 240.9 241
241.1 241.6 237.7 237.6 Sweet spot hit 236.6 234.5 228.2 224.5
236.9 236.2 237.6 237.5 237 234.4 234.5 Lower hit 217.3 217.5 217.4
217.2 220.6 223.2 230.8 233 222.9 220.5 224.9 Distance of (m) 13
14.3 16.2 18.5 9.1 8.2 5.3 3.3 12.3 5.7 4.3 Landing position *1 A:
Zr.sub.54Al.sub.10Cu.sub.30Ni.sub.5Hf.sub.1- , B:
Zr.sub.60Al.sub.10Cu.sub.20Ni.sub.10, C: Ti-6A1-4V, D: SUS630
[0063] T focus attention on the test results of the sweet spot
hitting, as the Young's modulus became smaller, the initial
velocity of the hit ball became higher and the carry became longer.
Thus, the rebound performance of the club head was improved.
[0064] In case of a small moment of inertia such as Ref., the carry
loss became increased in the lower hit in comparison with the sweet
spot hit. It is believed that the backspin was greatly increased by
a strong vertical gear effect.
[0065] In Examples 1 and 2 whose moment of inertia was larger than
Ref.1, the carry loss became small in the lower hit in comparison
with the sweet spot hit. It is believed that the backspin was
prevented from increasing even in the lower hit, and the vertical
gear effect was effectively controlled.
[0066] Incidentally, in case of the driver, backspin of a hit ball
which is preferable for obtaining a desirable ballistic course is
about 2000 to 3100 rpm. The backspin in Examples satisfied this
range in each of the sweet spot hit, upper hit and lower hit. Thus,
the carry can be improved.
[0067] In case of a relatively short gravity point distance such as
Examples 3 and 4, variation in the landing positions of the hit
balls was decreased and the directional stability was improved.
Thus, it is believed that the return of the club head was
improved.
[0068] The present invention can be suitably applied to wood-type
golf club heads as explained above, but it can be also applied to
various club heads such as iron-type and utility-type as far as a
hollow is formed behind the clubface.
* * * * *