Iron golf club

Abstract

The inventive iron golf club comprises a head part having a face, and a restitution coefficient is in the range of at least 0.81 and not more than 0.95 when colliding a ball against a sweet spot in the face at a speed of 44 m/s. In the aforementioned iron golf club, the effective face area of the head part is at least 2500 mm 2 and not more than 5000 mm 2 , the effective deflection length is at least 36 mm and not more than 72 mm, and the thickness of the face is at least 1.0 mm and not more than 2.5 mm at the sweet spot.

What is claimed is:  
     
         1 . An iron golf club comprising a head part having a face, wherein 
 a restitution coefficient is in the range of at least 0.81 and not more than 0.95 when colliding a ball against a sweet spot in said face at a speed of 44 m/s.    
     
     
         2 . The iron golf club according to    claim 1   , wherein 
 an effective face area being the surface area of a portion of said face deflectable at the hit is at least 2500 mm 2  and not more than 5000 mm 2 .    
     
     
         3 . The iron golf club according to    claim 1   , wherein 
 said head part has a hollow structure,    wall portions are provided on the peripheral edge of a face part in said head part, and    the surface area of a central portion of said face located between said wall portions is at least 2500 mm 2  and not more than 5000 mm 2 .    
     
     
         4 . The iron golf club according to    claim 1   , wherein 
 an effective deflection length being the length of a portion of said face deflectable at the hit, passing through said sweet spot of said face in a direction perpendicular to the ground, is at least 36 mm and not more than 72 mm.    
     
     
         5 . The iron golf club according to    claim 1   , wherein 
 said head part has a hollow structure,    wall portions are provided on the peripheral edge of a face part in said head part, and    an effective deflection length being the length between said wall portions, passing through said sweet spot of said face in a direction perpendicular to the ground, is at least 36 mm and not more than 72 mm.    
     
     
         6 . The iron golf club according to    claim 1   , wherein 
 the thickness of a face part is at least 1.0 mm and not more than 2.5 mm at said sweet spot of said face.    
     
     
         7 . The iron golf club according to    claim 1   , wherein 
 the elasticity of a face part in said head part is at least 30 GPa and not more than 210 GPa.