Golf club head with optimized moi and/or roll radius

Abstract

A golf club head with moments of inertia that are optimized about principal axes of the club head. The club head can have a roll radius about its ball striking face that is decreased above a first axis, and increased below the first axis, the first axis being correlated with the principal axes of the club head.

1 . A golf club head comprising:
 a hosel, strike face, and a body wall defining a hollow body substantially enclosing an inner volume; and   a weighted area of the body wall having a mass per unit area greater than an overall mass per unit area of the body wall, the weighted area being within a distance D of about 3 cm from a plane P that intersects the strike face, a toe side of a crown of the body, and a heel side of a sole of the body.   
     
     
         2 . The club head of  claim 1 , wherein a crown portion of the strike face is more curved than a sole portion of the strike face, as defined by:
 a loft line normal to, and passing through a geometric center of, the strike face;   a reference line through a club head center of gravity and parallel to the loft line;   a measuring line on a surface of the strike face comprising a series of evenly spaced points; and   N surface normals, each normal to and extending from the strike face at one of the points and each defining an angle θ N  with the next such that a θ i  above the reference line is larger than a θ j  beneath the reference line.   
     
     
         3 . The club head of  claim 2 , wherein the measuring line intersects the reference line and a vertical plane. 
     
     
         4 . The golf club of  claim 1 , wherein the plane P intersects a horizontal plane to define an angle between about 20° and about 40° when the club is at address. 
     
     
         5 . The club head of  claim 4 , wherein the plain P intersects the strike face within about 2 cm of a center of percussion. 
     
     
         6 . The club head of  claim 5 , wherein the plane P intersects the body within about 2 cm of an aft-most point on the club head. 
     
     
         7 . The club head of  claim 5 , wherein D is about 1 cm. 
     
     
         8 . The club head of  claim 4 , wherein the weighted portion of the body comprises two or more weight members fixed to the hollow body. 
     
     
         9 . The club head of  claim 4 , wherein the weighted portion of the body comprises a joining seam between a crown component and a sole component of the body wall. 
     
     
         10 . The golf club head of  claim 9 , wherein the seam comprises a filler material. 
     
     
         11 . The club head of  claim 10 , wherein a portion of seam is N-ply, and N>2. 
     
     
         12 . A golf club head comprising:
 a body coupled to a hosel;   a moment of inertia I Z  about an axis Z, wherein Z is vertical when at address;   a moment of inertia I A  about an axis A, wherein A intersects Z to define a non-zero angle θ A , and further wherein I A  is greater than I Z ; and   a strike face with a striking surface, wherein points evenly spaced in a line on the surface define N surface normals, each defining an angle θ N  with the next, such that a θ i  near a crown of the club head is larger than a θ j  near the sole.   
     
     
         13 . The golf club head of  claim 12 , wherein the angle θ A  is between about 5° and about 45°. 
     
     
         14 . The golf club head of  claim 12 , further comprising:
 a crown panel;   a sole panel; and   an assembly seam between the crown panel and the sole panel, the seam extending at least about halfway around the club head, wherein the assembly seam lies within a distance D of a plane P that is perpendicular to axis A, and D is less than about 2 cm.   
     
     
         15 . The golf club head of  claim 14 , wherein the seam comprises a filler material. 
     
     
         16 . The club head of  claim 14 , wherein a portion of seam is N-ply, and N>2. 
     
     
         17 . The golf club of  claim 14 , wherein θ A  is greater than 20° and θ B  is greater than 20°. 
     
     
         18 . The golf club head of  claim 12 , further comprising:
 a moment of inertia I Y  about an axis Y, wherein Y is horizontal and extends through a heel side of the club head and a toe side of the club head when the club is at address; and   a moment of inertia I B  about an axis B, wherein B intersects Y to define a non-zero angle θ B , and further wherein I B  is greater than T Y .   
     
     
         19 . The golf club of  claim 14 , wherein θ B  is between about 5° and about 45°. 
     
     
         20 . The golf club head of  claim 12 , wherein the line is vertical and there is a θ k , such that i≦k≦j and θ k =0. 
     
     
         21 . A golf club head comprising:
 a ball striking face comprising:
 a geometric center point located on a surface of the ball striking face, the geometric center point located generally equidistantly from an uppermost portion of the ball striking face and a lowermost portion of the ball striking face, as well as equidistantly from a heel and toe end of the ball striking face; 
 a vertical axis comprising an axis that extends through the geometric center point, the vertical axis oriented vertically relative to a flat playing surface when the club head is at an address position; 
 a horizontal axis extending through the geometric center point, the horizontal axis perpendicular to the vertical axis and extending horizontally and generally parallel to the flat playing surface, the horizontal axis comprising an axis that is angled at zero degrees relative to the address position when the club head is neither open nor closed at address; 
 a hitting zone defined by an anticipated or measured area on the ball striking face where a majority of a golfer's hits typically occur, the hitting zone having generally an elliptical shape angled upwardly from a heel side of the club head to a toe side of the club head; 
 a major axis extending through the elliptical hitting zone, the major axis defining a first principal axis of the club head, the major axis being tilted at a non-zero angle relative to the horizontal axis; 
 a minor axis extending perpendicular to the major axis, the minor axis defining a second principal axis of the club head, the minor axis tilted at the non-zero angle relative to the vertical axis; 
 wherein a moment of inertia of the club head about the major axis is greater than a moment of inertia of the club head about the horizontal axis; and 
 wherein the club head further comprises:
 a first roll radius, and 
 a second roll radius, the first roll radius smaller than the second roll radius. 
 
   
     
     
         22 . The club head of  claim 21 , further comprising:
 a loft line extending through the geometric center point, the loft line perpendicular to the ball striking face at the geometric center point;   a center of gravity;   a point of reference line extending through the center of gravity and the ball striking face, the point of reference line parallel to the loft line; and   an intersection point of the point of reference line and the ball striking face;   wherein the first roll radius is above the intersection point, and the second roll radius is below the intersection point.   
     
     
         23 . The club head of  claim 21 , wherein the majority comprises at least about 90 percent of a golfer's shots. 
     
     
         24 . The club head of  claim 21 , wherein the first major axis comprises a principal axis of the club head. 
     
     
         25 . The golf club head of  claim 21 , wherein the non-zero angle comprises between approximately 3.0 and 16.0 degrees. 
     
     
         26 . The golf club head of  claim 21 , wherein the first roll radius gives the ball striking face a rounded appearance when viewed from a side, and wherein the second roll radius gives the ball striking face a generally flattened appearance when viewed from the side.