CAN MANUFACTURE

摘要

A method for manufacture of a metal can body is described in which two or more stretching operations are used so as to reduce the thickness of the central part of a cup base, prior to drawing the cup sidewall and forming a can body. By using two or more stretching operations, it has been found possible to control the thickness of the base without significantly reducing pressure performance of the finished can. Alternative embodiments of apparatus comprising tooling for carrying out this method are also described.

主权项

1. A method for manufacture of a metal can body, the method comprising the following stages:
i) a first stretching stage comprising: on a cup having a sidewall and an integral base, the cup being formed of metal sheet, clamping an annular region on the base to define an enclosed portion which includes a central part of the base, and deforming and stretching at least some of that enclosed portion to thereby increase the surface area and reduce the thickness of the base; ii) a second stretching stage comprising: stretching a further enclosed part of the base, which includes the central part of the base; in which the annular clamping operation restricts metal flow from radially outside the clamped region into the enclosed portion during stretching; and iii) a drawing operation comprising drawing the cup into a can body by pulling and transferring material outwardly from the stretched and thinned base.