| 摘要 |
<p>The invention relates to extrusion processes incorporating a punch design having a non-cylindrical punch land. With the new design, a possible small tilt of the punch only gives rise to minor changes in the contact between can and punch. With the new design, great improvements can be obtained, as follows: 1) A small tilt will only give rise to minor differences or variations in can height. 2) The punch does not drift, which means that a can with more even wall thickness in the height direction will be produced, 3) As the can quality is nearly unaffected by small changes in the tilt angle, it will be much easier to keep the production under control. 4) The punch may be easier to manufacture.</p> |
