| 摘要 |
<p>PURPOSE: To resolve the restriction of the weight of a head body while increasing the moment of inertia to enable the enlargement of a sweet spot. CONSTITUTION: A head body 10 is formed of a plurality of split parts made of metal sheet material and these split parts are combined with each other to form a hollow shell structure made of the plastically worked metal sheet material 11 having no rib structure on the inner surface of a face surface part 10a. The thickness t1 of the face surface part of the head body is set to 2-3.5mm, the longitudinal length (a) to 40mm or more, lateral length (b) to 70mm or more, the thickness t2 of a crown surface part 10b to 0.6-2mm, the thickness t3 of a sole surface part 10c to 1-3mm, the whole volume to 190cc or more, the upper limit of the whole weight to the maximum 210g and the moment of inertia to 3000g.cm<2> or more while a value (moment of inertia/specific gravity of material) of the moment of inertia divided by the specific gravity of material is set to 400 or more.</p> |
