| 摘要 |
PURPOSE:To reduce the number of projections provided in a york to half, and extend the life of a press mold by preventing any shift of fins by making one end of a branching piece of a fin located in the lowest position of the axial direction in contact with the upper surface of a york projection, and making either the adjacent piece of the same fin as above or a piece corresponding to said branching piece of the lowest fin in contact with the side surface of said york projection. CONSTITUTION:The end of the nearest piece which is folded into an annular shape above a fin 2 located in the lowest position of the axial direction, is made in contact with the upper surface of a projection 9 so as to prevent the fin 2 from dropping even during overheating. In addition, a piece folded into an angular shape below an adjacent fin located next to the fin 2 is made in contact with the side surface of the same projection 9 so as to prevent any lateral shift of the fin 2. By thus using the projection 9 both for prevention of the fall of the fin and for prevention of the lateral shift of the fin, the number of projections provided in a york can be reduced to half, and the life of a york-formation press mold can be extended. |
