| 摘要 |
The method comprises the operations of:
- providing a strip of sheet metal (1) substantially shaped like an elongated parallelogram with an essentially uniform thickness;
- bending such a strip of sheet metal (1) and welding together the end portions (1a, 1b) so as to make a substantially cylindrical ring; and
- subjecting the ring (2) to press-moulding and shaping operations through plastic deformation so as to give it a desired shape. The strip of sheet metal (1) is bent so that its end portions (1a, 1b) are level and such end limbs (1a, 1b) are brought together and butt welded substantially on a same plane, so as to obtain a ring (2) which has a chordal flattened wall portion (1a, 1b). Before undergoing the aforementioned prcss-moulding and shaping operations, the ring (2) is subjected to a preliminary rounding operation through radial expansion. |
