Iron type golf club head

Abstract

A head 2 includes a face surface 4, a back surface 6, and a sole surface 8. The back surface 6 includes a top side region Rt and a sole side region Rs. The sole side region Rs includes a sole side inclination surface Sb 1 inclined to increase a face thickness toward a sole side, a plurality of back recessed parts Rb 1 formed on the sole side inclination surface Sb 1, and a wall WL 1 formed between the back recessed parts Rb 1 adjacent to each other. A low specific gravity member X 1 having a specific gravity lower than the specific gravity of the face material is disposed on at least one of the back recessed parts Rb 1. The head 2 has a loft angle of equal to or greater than 42°. The head 2 has a sweet spot height of equal to or greater than 19 mm.

What is claimed is: 
     
         1 . An iron type golf club head comprising a face surface formed by a face material, a back surface, and a sole surface extending between the face surface and the back surface, wherein
 the back surface includes a top side region and a sole side region positioned between the top side region and the sole surface,   the sole side region includes a sole side inclination surface inclined to increase a face thickness toward a sole side, a plurality of back recessed parts formed on the sole side inclination surface, and at least one wall formed between the back recessed parts adjacent to each other,   a low specific gravity member having a specific gravity lower than a specific gravity of the face material is disposed on at least one of the back recessed parts,   the golf club head has a loft angle of equal to or greater than 42°, and   the golf club head has a sweet spot height of equal to or greater than 18.5 mm.   
     
     
         2 . The iron type golf club head according to  claim 1 , wherein a high specific gravity member having a specific gravity higher than the specific gravity of the face material is disposed on the top side region. 
     
     
         3 . The iron type golf club head according to  claim 1 , wherein
 the number of the back recessed parts is equal to or greater than 5, and   the number of the walls is equal to or greater than 4.   
     
     
         4 . The iron type golf club head according to  claim 1 , wherein the low specific gravity member is not disposed on at least one of the back recessed parts. 
     
     
         5 . The iron type golf club head according to  claim 1 , wherein the plurality of back recessed parts are arranged in a toe-heel direction. 
     
     
         6 . The iron type golf club head according to  claim 1 , wherein the plurality of back recessed parts include a first back recessed part positioned on a most heel side, a second back recessed part positioned on a most toe side, and a third back recessed part positioned between the first back recessed part and the second back recessed part. 
     
     
         7 . The iron type golf club head according to  claim 1 , wherein each of the back recessed parts forms a space between the face surface and the sole surface. 
     
     
         8 . The iron type golf club head according to  claim 1 , wherein an inner surface of each back recessed part has a recessed part front surface which is a surface opposite to the face surface. 
     
     
         9 . The iron type golf club head according to  claim 1 , wherein the wall extends in a direction perpendicular to the face surface. 
     
     
         10 . The iron type golf club head according to  claim 2 , wherein the high specific gravity member has a center of gravity positioned on an upper side with respect to a center of gravity of the head. 
     
     
         11 . The iron type golf club head according to  claim 1 , wherein a total volume of the back recessed parts is equal to or greater than 3500 mm 3  but equal to or less than 6000 mm 3 . 
     
     
         12 . The iron type golf club head according to  claim 1 , wherein
 the plurality of walls are provided, and   an interval of the walls is equal to or greater than 4 mm but equal to or less than 12 mm.   
     
     
         13 . The iron type golf club head according to  claim 1 , wherein the wall has a thickness of equal to or greater than 1 mm but equal to or less than 4 mm. 
     
     
         14 . The iron type golf club head according to  claim 8 , wherein the low specific gravity member is brought into contact with the recessed part front surface.