| 摘要 |
Two-stage process for the production of preforms (2) of thermoplastic material, comprising the stages of extrusion and/or injection of a flow of molten resin into a mould provided with a plurality of individual cavities adapted to produce respective preforms (2), and removal of said preforms (2) from said cavities, followed by a stage in which a plurality of male elements (1) having outer dimensions that are substantially equal to the dimensions of the inner volume of the preform (2), are inserted in the respective preform (2) which is then allowed to cool down to such an extent as to cause it to shrink and tighten around the respective male element (1) owing to the effect of the resulting contraction. Such a cool-down is allowed to go on until the preform (2) becomes stable; the same preform (2) is then separated from the respective male element (1). Said preform (2) are not placed in any external cool-down or forming apparatus during this process. |
