METHOD OF AND APPARATUS FOR MANUFACTURING HOLLOW BODIES FROM THERMOPLASTICS MATERIAL

摘要

A method of an apparatus for manufacturing hollow bodies from thermoplastics material is disclosed. The thermoplastics material is placed in a mould cavity defined in a divided mould, which comprises a plurality of mould parts provided with mutually abutting surface portions defining closure means for the mould cavity. Heat is applied to the mould during a heating phase and the mould is then cooled during a cooling phase. The mould is rotated about each of two axes of rotation during the heating and cooling phase and, during the heating phase the interior of the mould is caused to be at a pressure lower then the pressure immediately external of the mould. The pressure in the mould is caused to at least approach the external pressure on transition to the cooling phase. Mould portions exterior of the cavity and immediately next adjacent the closure means are maintained - at least during a period extending from the start of the heating phase to the end of the cooling phase - at a pressure less than that occurring in the mould cavity during that period.