| 摘要 |
<p>Plasticized parisons of synthetic thermoplastic material are formed in an extrusion machine from where they are transferred to a station to be pneumatically converted in the cavity of an open-and-shut premold into hollow blanks which are larger than the parison but smaller than the desired shaped article. During such pneumatic conversion the material of the parison may be subjected to shock-like cooling concomitantly with conversion into the blanks, by appropriate cooling of the premold. The hollow blanks are then transferred to an intermediate station where they are subjected to thermal tempering in two or more separate stages, in order to bring them to an optimum temperature condition for the subsequent biaxial stretching. After tempering, the tempered blanks are transferred to another station to be pneumatically converted into respective shaped articles in the cavity of another open-and-shut mold and under biaxial stretching of their material.</p> |
