| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a feeling of security for selecting a club by applying the constitution that the marking groove area ratio of a middle iron group and a short iron group is gradually changed from the sole part to the crown part of the center longitudinal section of a face. SOLUTION: The groove area ratio of a marking 5 of score lines formed on the face of a club head 2 belonging to a middle iron group is gradually changed from a sole part 4a to a crown part 4b of the center longitudinal section of a face 4. That is, the groove area ratio of the sole part 4a is made larger than the groove area of the crown part 4b, and the ratio at the upper side 4x of the face 4 is kept at a value less than approximately 20% and at a value approximately between 20% and 50% at the lower side 4y via a boundary near the approximate center of the face 4. In addition, a difference in ratio between the sole part 4a and the crown part 4b is made at least 5%. A similar design applies to a short iron group. According to this construction, a carry becomes stable, and a drop in spin or the like is prevented. As a result, a club can be selected without anxiety.</p> |
