Golf club head
View Patent ↗A golf club head with an increased moment of inertia (MOI) about the X axis and the Z axis. Generally, the MOI about the Z axis is at least about 4400 g·cm 2 and the MOI about the X axis is at least about 2500 g·cm 2 . The radius of the bulge of the club face is increased while the radius of the roll is reduced to compensate for the gear effect produced by the increased MOIs. The bulge curvature is generally between about 0.016 cm −1 and about 0.028 cm −1 , and the roll curvature is between about 0.033 cm −1 and about 0.066 cm −1 . The roll curvature is greater than the bulge curvature.
1. A golf club head comprising:
a club head body having an external surface with a heel portion, a toe portion, a crown, a sole, and a face;
a moment of inertia about the CG Z axis, I zz ; and
a moment of inertia about the CG X axis, I xx , wherein I xx is at least about 3000 g·cm 2 and wherein I zz is greater than I xx ;
wherein the face includes:
a front side and a back side that define a variable face thickness;
a bulge curvature and a roll curvature; and
wherein a ratio of bulge curvature divided by roll curvature, R C , satisfies the following:
1
3.3
x
10
-
4
*
I
ZZ
+
0.9154
≤
R
C
≤
1
1.7
x
10
-
4
*
I
ZZ
+
0.4574
.
2. The golf club head of claim 1 wherein the roll curvature is between about 0.033 cm −1 and about 0.066 cm −1 , and wherein the bulge curvature is between about 0.016 cm −1 and about 0.028 cm −1 .
3. The golf club head of claim 1 wherein the golf club head has a mass between about 170 grams and about 220 grams.
4. A golf club comprising:
a shaft with a golf club head coupled thereto;
the club head body comprising:
an external surface with a heel portion, a toe portion, a crown, a sole, and a face;
a moment of inertia about the CG Z axis, I zz ; and
a moment of inertia about the CG X axis, I xx , wherein I xx is at least about 3000 g·cm 2 and wherein I zz is greater than I xx ;
wherein the face includes:
a front side and a back side that define a variable face thickness;
a bulge curvature and a roll curvature; and
wherein the ratio of the bulge curvature divided by the roll curvature, R C , satisfies the following:
1
(
5.6
x
10
-
4
*
I
ZZ
)
+
0.222
≤
R
C
≤
1
(
2.8
x
10
-
4
*
I
ZZ
)
+
0.111
.
wherein a bulge radius, R Bulge , is defined as the inverse of the bulge curvature, and
wherein R Bulge satisfies the equation R Bulge =0.0085×I ZZ +3.387.
5. The golf club of claim 4 wherein the ratio of the bulge curvature divided by the roll curvature, R C , is greater than about 0.28 and less than about 0.75.
6. The golf club of claim 4 wherein the roll curvature is between about 0.033 cm −1 and about 0.066 cm −1 , and wherein the bulge curvature is greater than 0 cm −1 and less than about 0.027 cm −1 and the inverse of the bulge curvature is greater than the inverse of the roll curvature by at least 7.62 cm.