BACKGROUND OF THE INVENTION This invention relates to a golf club head with impact control and flex increasing means.

Golf club heads generally comprise an inner end to be fastened to a shaft, an outer end, a front face and a back face, the front face and the back face being situated on opposite sides of a wall. The front face is the impact face, adapted to hit a golf ball.

US Patent 5,595,552 to Wright et al shows a golf club head having a cavity in the back face, surrounded by a perimeter frame. The frame, in particular along the bottom and the outer end of the head, has a relatively large thickness, and is a weighting element. Ribs extend radially from a center of the wall defining the bottom of the cavity to the perimeter frame. The purpose of these ribs is to eliminate undesirable vibrations in the golf club head during impact against a golf ball and to dampen other vibrations. The wall at the bottom of the cavity may also comprise a ring encircling a projection at the center of gravity of the club head body, and these members, together with the ribs, constitute means for tuning the club head and for controlling vibrations, in order to improve the sound and feel of the golf club during impact against a golf ball.

SUMMARY OF THE INVENTION.

According to the present invention it has been recognized that improved dampening of vibrations and a better feel can be achieved by providing, in a wall defing the bottom of a cavity in the back face of a golf club, a plurality of mainly parallel holes mainly perpendicular to the front face and extending into the wall from the back face, but not entirely through the wall.

A particularly desirable effect is achieved by shaping the wall in such a manner that its thickness is varying, by being greatest near the central portion of the wall. The holes may have varying depths, whereby the depths are largest where the wall thickness is largest, in such a manner that the portions of the wall between the bottoms of the holes and the front face of the wall mainly are of constant thickness.

Moreover, the holes may be conical, having the smallest cross section at their bottoms.

This arrangement of holes gives the club head a larger"sweetspot"compared with prior art club heads, and cause a particular flexing or bending of the club head wall during impact.

The holes cause particular properties with respect to bending stiffness of the club head; i. e. of the wall thereof.

The above described effect may be further increased, by shaping the wall with a varying thickness. A wall having such a varying thickness may be compared with a beam being mounted at each end and being subjected to a bending load at or near its middle point, in a direction perpendicular to the main plane of the wall.

Professional golf players may use clubs having a greater wall stiffness than clubs adapted to amateur players.

The golf club head according to the present invention can be made, for instance cast, from any suitable material used for golf club heads, such as steel or metal alloys. The holes may, however, be drille.

DESCRIPTION OF THE DRAWINGS.

Fig. 1 is a perspective view of the golf club head according to the present invention.

Fig. 2 shows a section through a golf club head, taken through a row of holes.

Fig. 3 shows a section through the golf club head, perpendicular to the section of Fig. 2, through another row of holes.

DESCRIPTION OF A PREFERRED EMBODIMENT.

The Figs. show a golf club head according to the present invention, comprising a socket 1 adapted to be fastened to an end of a (not shown) club shaft, a frame 2 surrounding the main portion of the club head, a front face 3 on one side of a wall 6, a back face 5 on the opposite side of the wall 6, said back face 5 being the bottom of a cavity which is surrounded by the frame 2, and holes 4 in the wall 6. The holes 4 are parallel to each other and mainly perpendicular to the front face 3 of the wall 6. The cross section shape of the holes 4 is shown in Fig. 1 to be circular, but this shape is not a limitation, as the cross section shape may be for instance elliptical, rectangular, possibly with rounded corners, or similar.

A possible longitudinal section of the holes 4 is shown in Figs. 2 and 3. As shown, the holes 4 are conical. Also as shown in Figs. 2 and 3, the overall thickness of the wall 6 is largest in its central portion 7 and smallest in portions 8 near the frame 2. Thus, the bending stiffness of the wall 6 is highest in the central portion 7.

The effect of the holes 4 and the varying wall thickness is that the wall 6 has varying properties with respect to stiffness across the faces 3 and 5.

The number of holes 4 is not critical. The stiffness of the wall 6 can be adjusted by the number of holes 4 and their dimensions (height and/or cross section shape), in addition to the overall thickness of the wall 6.