GOLF CLUB HEAD

• US 20080113825A1
• Filed: 11/09/2007
• Published: 05/15/2008
• Est. Priority Date: 11/10/2006
• Status: Abandoned Application

• Current Assignee: K.K. Endo Seisakusho
• Original Assignee: K.K. Endo Seisakusho
• Inventors: ARIYOSHI, Ken, FUNAYAMA, Tomonari, SAKAI, Tomoyuki
• Application Number:
  US11/937,868
• Publication Number:
  US 20080113825A1
• Time in Patent Office: Days
• US Class Current: 473/291
• CPC Class Codes: A63B 2053/0491 with added weights, e.g. changeable, replaceable
• CPC Class Codes: A63B 2209/00 Characteristics of used materials
• CPC Class Codes: A63B 53/0408 characterised by specific dimensions, e.g. thickness
• CPC Class Codes: A63B 53/0412 Volume
• CPC Class Codes: A63B 53/0416 Heads having an impact surface provided by a face insert
• CPC Class Codes: A63B 53/0458 with non-uniform thickness of the impact face plate
• CPC Class Codes: A63B 53/0466 wood-type
• CPC Class Codes: A63B 60/02 Ballast means for adjusting the centre of mass A63B60/24, A63B60/54 take precedence

Abstract

A golf club having an increased moment of inertia and improved ball-hitting directionality is provided. A metal hollow golf club head comprises: a face portion; a crown portion; and a sole portion, and when the golf club has a lie angle of 60° with its club head volume being within 470 cm³, a moment of inertia about the axial line centered on the plumb line passing through the golf club head center of gravity is 5000 to 6000 g-cm². In order to increase the moment of inertia, the thickness of the center portion of the crown portion is reduced by chemical etching, and a mass, including the portion of mass reduction, is positioned in the sole portion on the side of the toe portion; moreover, the separation distance from the center of gravity to the mass is increased.

Claims

1. A golf club, comprising:

a face portion positioned on a front surface of a metal hollow golf club head and having a striking face to strike a golf ball;

a crown portion forming an upper surface of the club, and a sole portion forming a lower surface of the club, wherein

the mass of the metal hollow golf club head is 210 g or less,

characteristic time (CT value) of the metal hollow golf club head, relating to a restitution characteristic, is 257 μ

s or less; and

when a lie angle of the metal hollow golf club head is 60°

, volume of the metal hollow golf club head is 470 cm³ or less, and moment of inertia about an axial line which is the center of a plumb line passing through the center of gravity of the metal hollow golf club head, is in the range 5000 to 6000 g-cm².

2. The golf club according to claim 1, wherein the metal is a titanium alloy sheet member, and a substantial center portion and an outer peripheral portion including sites of the plumb line within the curved surface of the crown portion and/or the sole portion constituting the body differ in thickness.

3. The golf club according to claim 1 or claim 2, wherein the metal hollow golf club head is formed by joining, by welding, the face portion, the sole portion, the crown portion, and a hosel portion to which the shaft is connected.

4. The golf club according to claim 2, wherein a weight of 20 g or more is positioned at the position of a rotation radius most distant from the plumb line and at the crown portion and/or the sole portion.

5. The golf club according to claim 4, wherein the weight is positioned on a back side of the toe portion.

6. The golf club according to claim 5, wherein toe-side and back-side sites of the sole portion are formed in shapes protruding outward relative to the crown portion, and the weight is positioned in this protruding sole portion.

7. The golf club according to claim 1, wherein

the metal hollow golf club head has:

a length (X) from the heel portion to the toe portion longer than a length (Y) from the face portion to the rear surface;

a length from the heel to the toe of 127 mm (5 inches) or less;

a length from the sole to the crown of 71.12 mm (2.8 inches) or less; and

a moment of inertia (MOI) within a range calculated using the following approximating equation (1);

MOI=(aY²+bY+c)×

(dX+e)/f 

 

(1)

where X is the length from the heel portion to the toe portion, Y is the length from the face portion to the rear surface, and a, b, c, d, e, and f are constants.

8. The golf club according to claim 1, wherein

the metal hollow golf club head has:

a length (X) from the heel portion to the toe portion longer than a length (Y) from the face portion to the rear surface;

a length from the heel to the toe of 127 mm (5 inches) or less;

a length from the sole to the crown of 71.12 mm (2.8 inches) or less; and

a position of the center of gravity, as seen from the plumb direction, existing within a range encompassed by the following two equations;

Y=−

gX²+hX²+i 

 

(2)

Y=−

jX²+k 

 

(3)

where X is the position in the direction from the heel portion to the toe portion, Y is the position in the direction from the face portion to the rear surface, g, h, j, and k are constants, the X has an origin at the center of the distance from the heel portion to the toe portion, and the Y has an origin in the face surface.