Only two types of irons were used during the feathery ball era, the sand iron with a large concave face and the rut iron which had a very small head.

在羽毛高尔夫球时代，仅有两种高尔夫球杆被使用，一种是带有大凹杆面的沙铁杆，另一种是杆头很小的。

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The taper ring's irregular section shape decide the unequal forming of the ring metal when rolling ring, which is the main cause of irregular wide spread and draw concave on the symmetry face of ring.

锥形套圈由于它截面形状的不规则性决定了辗扩过程金属变形的不均匀性，这是导致不规则宽展、拉凹的主要原因。

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Results: In 12 cases, the concave of the face or frontal were reconstructed with good appearance and without any complications.

结果：12例额面凹陷畸形获得整复，外形好，无并发症。

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