Golf club head
A golf club head includes a top portion, a sole portion opposite the top portion, and a striking face configured to impact a golf ball. The striking face includes a face center and a variable thickness distribution such that the club head exhibits an Expected COR value of not less than 0.810, the Expected COR value being determined based on the following relationship Expected COR = ∑ i = 1 n ∑ j = 1 m p ij * c ij The variable c ij corresponds to an average COR value associated with bin and the variable p ij corresponds to a bin-specific impact probability value. And the club head exhibits a characteristic time no greater than 257 microseconds.
1. A golf club head comprising:
a top portion;
a sole portion opposite the top portion; and
a striking face configured to impact a golf ball, the striking face comprising a face center and a variable thickness distribution such that the golf club head exhibits a maximum CT value, CT max , that satisfies the following expression:
Expected COR≥ 0.0006 μs −1 ×CT max +0.6597,
the Expected COR value being determined based on the following relationship:
Expected
COR
=
∑
i
=
1
n
∑
j
=
1
m
p
ij
*
c
ij
wherein:
(a) a virtual rectangular evaluation region is superimposed onto the striking face, the virtual rectangular evaluation region comprising a first pair of horizontal sides having a length of 45 mm, a second pair of vertical sides having a length of 25 mm, and a geometric center that coincides with the face center;
(b) the virtual rectangular evaluation region is divided into 5 rows (m) having an equal height of 5 mm and is divided into 9 columns (n) having an equal width of 5 mm, thereby forming a matrix of bins having coordinates i and j;
(c) c ij corresponds to an average COR value associated with bin i, j;
(d) p ij corresponds to a bin-specific impact probability value in accordance with the following:
P
(
i
,
j
)
=
0.00
%
1.60
%
2.50
%
2.50
%
3.00
%
2.70
%
1.60
%
0.80
%
0.10
%
0.60
%
2.10
%
3.30
%
4.50
%
4.60
%
4.90
%
2.10
%
1.60
%
0.30
%
0.80
%
2.00
%
3.00
%
5.00
%
6.00
%
4.50
%
2.40
%
1.80
%
0.90
%
0.20
%
1.20
%
2.90
%
3.70
%
4.00
%
3.00
%
2.50
%
2.10
%
1.20
%
0.00
%
0.70
%
1.60
%
2.50
%
2.90
%
2.00
%
1.60
%
1.60
%
1.00
%
;
and
(e) the golf club head exhibits a characteristic time no greater than 257 microseconds.
2. The golf club head according to claim 1 , wherein the characteristic time is not less than 237 microseconds.
3. The golf club head according to claim 1 , wherein the expected COR value and a maximum COR value COR max of the striking face satisfy a following expression:
Expected COR≥ 0.844× COR max +0.1135.
4. The golf club head according to claim 1 , wherein the expected COR value and a value of moment of inertia (MOI) (g·cm 2 ) satisfy the following expression:
Expected COR≥ 0.00001× MOI+ 0.7664; and
wherein the MOI is the value of moment of inertia around a vertical axis passing through a center of gravity of the head in a reference position in which the golf club head is held at predetermined lie angle and loft angle.
5. The golf club head of claim 1 , wherein the striking face further comprises a central thickened region located intermediate a heel region and a toe region, the central thickened region having a thickness greater than the heel region and the toe region.
6. The golf club head of claim 5 , wherein the central thickened region comprises a generally constant thickness.
7. The golf club head of claim 5 , wherein the central thickened region comprises a generally triangular shape.
8. The golf club head of claim 5 , wherein the central thickened region comprises a thickness between 3.4 mm and 3.9 mm.
9. The golf club head of claim 8 , wherein the heel region and the toe region each comprise a thickness between 1.9 mm and 2.4 mm.
10. A golf club head comprising:
a top portion;
a sole portion opposite the top portion; and
a striking face configured to impact a golf ball, the striking face comprising a face center and a variable thickness distribution such that the golf club head exhibits a maximum COR value, COR max , that satisfied the following expression:
Expected COR≥ 0.844× COR max +0.1135,
the Expected COR value being determined based on the following relationship:
Expected
COR
=
∑
i
=
1
n
∑
j
=
1
m
p
ij
*
c
ij
wherein:
(a) a virtual rectangular evaluation region is superimposed onto the striking face, the virtual rectangular evaluation region comprising a first pair of horizontal sides having a length of 45 mm, a second pair of vertical sides having a length of 25 mm, and a geometric center that coincides with the face center;
(b) the virtual rectangular evaluation region is divided into 5 rows (m) having an equal height of 5 mm and is divided into 9 columns (n) having an equal width of 5 mm, thereby forming a matrix of bins having coordinates i and j;
(c) c ij corresponds to an average COR value associated with bin i, j;
(d) p ij corresponds to a bin-specific impact probability value in accordance with the following:
P
(
i
,
j
)
=
0.00
%
1.60
%
2.50
%
2.50
%
3.00
%
2.70
%
1.60
%
0.80
%
0.10
%
0.60
%
2.10
%
3.30
%
4.50
%
4.60
%
4.90
%
2.10
%
1.60
%
0.30
%
0.80
%
2.00
%
3.00
%
5.00
%
6.00
%
4.50
%
2.40
%
1.80
%
0.90
%
0.20
%
1.20
%
2.90
%
3.70
%
4.00
%
3.00
%
2.50
%
2.10
%
1.20
%
0.00
%
0.70
%
1.60
%
2.50
%
2.90
%
2.00
%
1.60
%
1.60
%
1.00
%
;
and
(e) the golf club head exhibits a characteristic time no greater than 257 microseconds.
11. The golf club head according to claim 10 , wherein the characteristic time is not less than 237 microseconds.
12. The golf club head according to claim 10 , wherein the expected COR value and a value of moment of inertia (MOI) (g·cm 2 ) satisfy the following expression:
Expected COR≥ 0.00001× MOI+ 0.7664; and
wherein the MOI is the value of moment of inertia around a vertical axis passing through a center of gravity of the golf club head in a reference position in which the golf club head is held at predetermined lie angle and loft angle.
13. The golf club head of claim 10 , wherein the striking face further comprises a central thickened region located intermediate a heel region and a toe region, the central thickened region having a thickness greater than the heel region and the toe region.
14. The golf club head of claim 13 , wherein the central region comprises a generally constant thickness.
15. The golf club head of claim 13 , wherein the central region comprises a generally triangular shape.
16. The golf club head of claim 13 , wherein the central region comprises a thickness between 3.4 mm and 3.9 mm.
17. The golf club head of claim 13 , wherein the striking face comprises a generally ovate shape.