Hot moulding of shell-like thermoplastic articles - allowing rapid opening of mould, for drum bodies etc.

摘要

Method of hot moulding a shell-like thermoplastic article in a mould of which the cover, which is provided with a cooling circuit, is applied to the concave surface of the article, is carried out by forming in the concave surface, by means of deep narrow slots in the cover, several thin panels parallel to the section of greatest curvature and braced by at least one perpendicular thin panel. The mould is opened when the panels have solidified, and the panels may be removed by machining after the article has completely cooled if they are unsuitable for the use intended for the article. The method may be used for sections of a drum body, the transverse panels, which are circle segment-shaped, are arranged with their ends set back from the longitudinal edges of the drum body to form passages for the drum stay rods; the end transverse panels are set back from the curved transverse edges of the drum body.