Golf club head

1. A golf club head for a fairway wood or alternatively a utility type club head, said golf club head having a hollow structure comprising a face portion having a club face for hitting a ball, a crown portion connecting the face portion at an upper edge thereof and forming an upper surface of the club head, and a sole portion connecting the face portion at a lower edge thereof and forming an under surface of the club head, and being composed of a head main body including a part of the face portion provided with an opening, and a face member fitted in the opening and welded to the head main body,

wherein

a front surface and a back surface of the face member define a part of the club face and a part of a back surface of the face portion, respectively,

a thickness of the face member defined between said front surface and said back surface is constant,

a welded part between the face member and the head main body includes:

a crown-side welded part positioned substantially at the upper edge or alternatively spaced apart from the upper edge toward the lower edge by a certain distance (A), and

a sole-side welded part spaced apart from the lower edge toward the upper edge by a certain distance B which is more than zero and more than the distance (A),

wherein:

the distance (A) is defined by a distance measured in the up-down direction of the head between a widthwise center of the crown-side welded part appearing in the club face and the upper edge of the face portion, and

the distance B is defined by a distance measured in the up-down direction of the head between a widthwise center of the sole-side welded part appearing in the club face and the lower edge of the face portion,

the face portion is provided between the sole-side welded part and the lower edge with a sole-side thin area whose thickness is less than the constant thickness of the face member, wherein, the front surface and the back surface of the sole-side thin area define a part of the club face and a part of the back surface, respectively, of the face portion, and the thickness of the sole-side thin area is defined between said front surface and said back surface,

the face portion is provided between the crown-side welded part and the upper edge with a crown-side thin area whose thickness is less than the constant thickness of the face member, wherein the front surface and the back surface of the crown-side thin area define a part of the club face and a part of the back surface, respectively, of the face portion, and the thickness of the crown-side thin area is defined between said front surface and said back surface of the crown-side thin area,

the sole-side thin area and the crown-side thin area are formed from said part of the face portion provided with the opening,

the thickness of the sole-side thin area is less than the thickness of the crown-side thin area,

the thickness of the sole-side thin area is 70% to 95% of the constant thickness of the face member,

a length of the sole-side thin area measured in a toe-heel direction of the head is not less than 50% and not more than 90% of the length of the club face measured in the toe-heel direction at the position of a sweet spot of the club face, and

a length of the crown-side thin area measured in the toe-heel direction is not less than 80% of the length of the club face.

2. The golf club head according to claim 1 , wherein the thickness of the sole-side thin area is 0.5 to 2.0 mm.

3. The golf club head according to claim 2 , wherein the distance B is not less than 5 mm, and the distance (A) is not more than 3 mm.

4. The golf club head according to claim 3 , wherein the distance B is not less than 15% of a height of the club head, and the distance (A) is not more than 5% of the height of the club head.

5. The golf club head according to claim 1 , wherein the distance B is not less than 5 mm, and the distance (A) is not more than 3 mm.

6. The golf club head according to claim 5 , wherein the distance B is not less than 15% of a height of the club head, and the distance (A) is not more than 5% of the height of the club head.

7. The golf club head according to claim 1 , wherein the distance B is not less than 15% of a height of the club head, and the distance (A) is not more than 5% of the height of the club head.

8. The golf club head according to claim 7 , wherein the thickness of the sole-side thin area is 0.5 to 2.0 mm.

9. The golf club head according to claim 1 , wherein a difference of the distance B from the distance (A) is more than 2 mm.

10. A golf club head for a fairway wood or alternatively a utility type club head, said golf club head having a hollow structure having an inner cavity, the hollow structure comprising:

a face portion having a club face for hitting a ball;

a crown portion connecting the face portion at an upper edge thereof and forming an upper surface of the club head; and

a sole portion connecting the face portion at a lower edge thereof and forming an under surface of the club head,

said golf club head being composed of:

a head main body including a part of the face portion provided with an opening, and

a face member fitted in the opening and welded to the head main body,

wherein

a front surface and a back surface of the face member define a part of the club face and a part of a back surface of the face portion, respectively,

the thickness of the face member defined between said front surface and said back surface is constant,

a welded part between the face member and the head main body includes:

a crown-side welded part positioned substantially at the upper edge or alternatively spaced apart from the upper edge toward the lower edge by a certain distance (A), and

a sole-side welded part spaced apart from the lower edge toward the upper edge by a certain distance B which is more than zero and more than the distance (A),

wherein:

the distance (A) is defined by a distance measured in the up-down direction of the head between a widthwise center of the crown-side welded part appearing in the club face and the upper edge of the face portion, and

the distance B is defined by a distance measured in the up-down direction of the head between a widthwise center of the sole-side welded part appearing in the club face and the lower edge of the face portion,

in the welded part between the face member and the head main body, a gap formed therebetween is filled with a weld metal,

the face portion is provided between the sole-side welded part and the lower edge with a sole-side thin area whose thickness is less than the constant thickness of the face member, wherein, the front surface and the back surface of the sole-side thin area define a part of the club face and a part of the back surface, respectively, of the face portion, and the thickness of the sole-side thin area is defined between said front surface and said back surface,

the face portion is provided between the crown-side welded part and the upper edge with a crown-side thin area whose thickness is less than the constant thickness of the face member, wherein, the front surface and the back surface of the crown-side thin area define a part of the club face and a part of the back surface, respectively, of the face portion, and the thickness of the crown-side thin area is defined between said front surface and said back surface of the crown-side thin area,

the sole-side thin area and the crown-side thin area are formed from said part of the face portion provided with the opening,

the thickness of the sole-side thin area is less than the thickness of the crown-side thin area,

the thickness of the sole-side thin area is 70% to 95% of the constant thickness of the face member,

in the sole-side welded part, the weld metal reaches to said inner cavity so that, by the weld metal between the sole-side thin area and the face member, the face portion is provided at a position of the sole-side welded part with a thickness more than the thickness of the sole-side thin area and less than the thickness of the face member to make the thickness change from the sole-side thin area to the face member gradual,

a length of the sole-side thin area measured in a toe-heel direction of the head is not less than 50% and not more than 90% of the length of the club face measured in the toe-heel direction at the position of a sweet spot of the club face, and

a length of the crown-side thin area measured in the toe-heel direction is not less than 80% of the length of the club face.