| 摘要 |
<p>A method of forming an elongated, narrowed neck (225) on an impact extruded metal container, in which a larger portion is trimmed from the open end of the container than is necessary merely to produce a straight unwrinkled edge. The trimmed part (111a, 111b) is sufficiently long that the metal at the new edge (112a, 112b) formed by trimming comprises substantially more formable metal than the metal which would have been present at the edge produced by normal trimming. The increased formability occurs because excess impurities which migrate to the open edge of the container are largely removed by the deep trim. The method is further assisted by trimming the end of the neck again partway through a series of neck-forming dies (120), and by using compressed air in the first few dies to aid in ejecting the containers from the dies.</p> |
