A golf club head comprises has an inner surface including a back surface of the face portion that is provided with a crown-side thick-walled rib and a sole-side thick-walled rib. The crown-side thick-walled rib includes an upper face rib disposed in the face portion and extending from the central thick-walled part to a peripheral edge of the back surface of the face portion on a crown portion side, and a crown rib disposed in the crown portion and extending backwardly of the head from the upper face rib. The sole-side thick-walled rib includes a lower face rib disposed in the face portion and extending from the central thick-walled part to a peripheral edge of the back surface of the face portion on a sole portion side, and a sole rib disposed in the sole portion and extending backwardly of the head from the lower face rib.
1. A golf club head having a hollow structure comprising
a face portion which has a face to hit a golf ball,
a crown portion which connects to an upper edge of the face and forms a top surface of the head,
a sole portion which connects to a lower edge of the face and forms a bottom surface of the head, and
a side portion between the crown portion and the sole portion, which extends from a toe-side edge of the face to a heel-side edge of the face through a back face of the head, wherein
the face portion is provided in a central region thereof with a central thick-walled part having a thickness of 3.1 to 4.2 mm, and
an inner surface of the head including a back surface of the face portion is provided with a crown-side thick-walled rib and a sole-side thick-walled rib,
the crown-side thick-walled rib including
an upper face rib which is disposed in the face portion and extends from the central thick-walled part to a peripheral edge of said back surface of the face portion on a crown portion side, and
a crown rib which is disposed in the crown portion and extends backwardly of the head from the upper face rib, and
the sole-side thick-walled rib including
a lower face rib which is disposed in the face portion and extends from the central thick-walled part to a peripheral edge of the back surface of the face portion on a sole portion side and
a sole rib which is disposed in the sole portion and extends backwardly of the head from the lower face rib,
wherein the following expressions are satisfied:
Tc≧Tru,
Tc≧Trd,
Wc≧Wru, and
Wc≧Wrd,
wherein
Tc is a thickness of the central thick-walled part,
Wc is a maximum width of the central thick-walled part in the toe-heel direction,
Wru is a width of the crown-side thick-walled rib in the toe-heel direction,
Wrd is a width of the sole-side thick-walled rib in the toe-heel direction,
Tru is an average thickness of the crown-side thick-walled rib, and
Trd is an average thickness of the sole-side thick-walled rib.
2. The golf club head according to claim 1 , wherein the following expressions are satisfied:
Tru>Tcrt,
Trd>Tcrt,
Tru>Tsrt,
Trd>Tsrt, and
Tsrt>Tcrt,
wherein
Tru is the average thickness of the crown-side thick-walled rib,
Trd is the average thickness of the sole-side thick-walled rib,
Tcrt is an average thickness of the crown rib, and
Tsrt is an average thickness of the sole rib.
3. The golf club head according to claim 1 , wherein
the face portion is further provided with a thin-walled part having a thickness of from 1.9 to 2.6 mm, and
the following expressions are satisfied:
Tc>Tp,
Tru>Tp,
Trd>Tp,
Tp>Tcrt, and
Tp>Tsrt,
wherein
Tp is an average thickness of the thin-walled part.
Tc is the thickness of the central thick-walled part,
Tru is the average thickness of the crown-side thick-walled rib,
Trd is the average thickness of the sole-side thick-walled rib,
Tcrt is the average thickness of the crown rib, and
Tsrt is the average thickness of the sole rib.
4. A golf club head having a hollow structure comprising
a face portion which has a face to hit a golf ball,
a crown portion which connects to an upper edge of the face and forms a top surface of the head,
a sole portion which connects to a lower edge of the face and forms a bottom surface of the head, and
a side portion between the crown portion and the sole portion, which extends from a toe-side edge of the face to a heel-side edge of the face through a back face of the head,
wherein
the face portion is provided in a central region thereof with a central thick-walled part having a thickness of 3.1 to 4.2 mm, and
an inner surface of the head including a back surface of the face portion is provided with a crown-side thick-walled rib and a sole-side thick-walled rib,
the crown-side thick-walled rib including
an upper face rib which is disposed in the face portion and extends from the central thick-walled part to a peripheral edge of said back surface of the face portion on a crown portion side, and
a crown rib which is disposed in the crown portion and extends backwardly of the head from the upper face rib, and
the sole-side thick-walled rib including
a lower face rib which is disposed in the face portion and extends from the central thick-walled part to a peripheral edge of the back surface of the face portion on a sole portion side and
a sole rib which is disposed in the sole portion and extends backwardly of the head from the lower face rib,
wherein in a reference state in which the club head is set on a horizontal plane at its lie angle and loft angle, the crown rib is disposed on one side of a vertical plane, and the sole rib is provided on the other side of the vertical plane,
wherein the vertical plane is defined as including a sweet spot of the face and being parallel with the front-back direction of the head.