Iron golf club

Abstract

An iron golf club for enhancing the gear effect and accelerating backspin of a ball. The head, which comprises a face part having a ball-hitting surface, a sole part having a ground-contact plane in the bottom portion of the head, a top part, and a hosel part, is configured such that the rigidity on the ground-contact plane side of the bottom portion is lowered by either providing the portion with a cavity or changing its material. Further, the vertical moment of inertia of the head is reduced by disposing a weight in the location of the center of gravity of the head. When the length of the hosel part is 50 mm or longer, the value of the moment of inertia becomes less than 800 g·cm 2 , and when the length of the hosel part is less than 50 mm, the value of the moment of inertia becomes 750 g·cm 2 or less. These configurations realize a golf club that enhances the gear effect and accelerates spin of a ball.

1 . An iron golf club, comprising:
 a head having, in a lower portion thereof, a sole part which has a ground-contact plane, and having, in an upper portion thereof, a top part, and a face part which has a ball-hitting surface for striking a ball, and, at one end thereof, a hosel part which is a shaft connector; and   a shaft, which is connected at one end thereof to the hosel part,   a ground-contact plane side of the head being configured to have low rigidity.   
   
   
       2 . The iron golf club according to  claim 1 , wherein a top part side of the head is configured to have relatively higher rigidity than the ground-contact plane side. 
   
   
       3 . The iron golf club according to  claim 1 , wherein the ground-contact plane side of the head has a relatively higher coefficient of rebound than the top part side of the head. 
   
   
       4 . The iron golf club according to  claim 1 , wherein the ground-contact plane side of the head is in an area nearer to the sole part side than to an approximate horizontal plane which is parallel to a score line, and which passes through a location of the center of gravity. 
   
   
       5 . An iron golf club, comprising:
 a head having, in a lower portion thereof, a sole part which has a ground-contact plane, and having, in an upper portion thereof, a top part, and a face part which has a ball-hitting surface for striking a ball, and, at one end thereof, a hosel part which is a shaft connector; and   a shaft, which is connected at one end thereof to the hosel part, wherein
 when a length of the hosel part is 50 mm or longer, a value of a moment of inertia centering on an axis that passes horizontally in a toe-heel direction through the center of gravity of the head is less than 800 g·cm 2 . 
   
   
   
       6 . An iron golf club, comprising:
 a head having, in a lower portion thereof, a sole part which has a ground-contact plane, and having, in an upper portion thereof, a top part, and a face part which has a ball-hitting surface for striking a ball, and, at one end thereof, a hosel part which is a shaft connector; and   a shaft, which is connected at one end thereof to the hosel part, wherein   when a length of the hosel part is less than 50 mm, a value of a moment of inertia centering on an axis that passes horizontally in a toe-heel direction through the center of gravity of the head is less than 750 g·cm 2 .   
   
   
       7 . The iron golf club according to  claim 1 , wherein a specific gravity of a material for configuring the main parts of the head is 6.5 g·cm 2  or greater. 
   
   
       8 . The iron golf club according to  claim 1 , wherein the head is either the head of a short iron or the head of a wedge. 
   
   
       9 . The iron golf club according to  claim 2 , wherein the ground-contact plane side of the head is in an area nearer to the sole part side than to an approximate horizontal plane which is parallel to a score line, and which passes through a location of the center of gravity. 
   
   
       10 . The iron golf club according to  claim 3 , wherein the ground-contact plane side of the head is in an area nearer to the sole part side than to an approximate horizontal plane which is parallel to a score line, and which passes through a location of the center of gravity. 
   
   
       11 . The iron golf club according to  claim 6 , wherein a specific gravity of a material for configuring the main parts of the head is 6.5 g·cm 2  or greater. 
   
   
       12 . The iron golf club according to  claim 6 , wherein the head is either the head of a short iron or the head of a wedge.