| 摘要 |
<p>The method comprises a first process step consisting of shearing a cylindrical drawn segment on which there is carried out a cold impact extrusion by means of a punch. In that step the material flows laterally up to form a constant pattern hollow body (9) having at least one open end, on the other end (8) there being formed a solid pin (11) and a second open cavity of a smaller size. On each hollow body there are then carried out successive upsetting at the open end, adapted to impart the same with an undulated conformation. That end is then upturned and blocked.</p> |
