| 摘要 |
<p>PURPOSE:To solve the question of the directional property of a ball becoming the more deteriorating increasingly, when the more lower order iron club is used out of a plurality of iron clubs, by gradually increasing the horizontal length of the face of the iron club, as the use order of the iron club lowers, and by gradually decreasing the thickness of a striking part from a face plane to the cavity bottom face of a back face, as the use order of the iron club lowers. CONSTITUTION:The horizontal length L of the face of an iron club out of plurality of iron clubs each equipped with a head having a cavity 1 in back face 2 is increased gradually as the order of use of the iron club lowers. The thickness T of a striking part from a face plane 7 to the cavity bottom face 1a of the back face 2 is decreased gradually as the use order of the iron club more lowers. As a result, the moment of inertia of the head is increased gradually, as the use order of the iron club more lowers, so that it is possible to improve the ball-hitting rate of the club of low order and to improve the directional property of a ball. Also, the appearance of all club heads in a set can be made orderly and free of an odd appearance, and it is further possible to manufacture the heads at a low cost and simply without requiring any complicated or special process.</p> |
