| 摘要 |
<p>A process for manufacturing a preform for a container made of a plastics material which becomes crystalline when heated, for example PET, PEN or copolymers of PET/PEN. A container blank is heated at least in a mouth section (4) to crystallisation temperature, so that it is crystallised by 20 %. During crystallisation, the outside diameter of the mouth section (4) shrinks from an initial value (A) to a smaller intermediate value (Z). In a further step, the mouth section (4) is expanded by an expanding mandrel (15) against an external mould in such a way that its outside diameter has a final value (E), which is between the initial value (A) and the intermediate value (Z). The wall thickness of the mouth section (4) is thereby reduced from an initial value (d1) to a final value (d3).</p> |
