Perforated, blow-moulded thermoplastics, container mfr. - by piercing an inflated parison with needles which are retracted after cooling

摘要

Mfr. of a perforated thermoplastics blow-moulding esp. a container, comprises introducing a parison between 2 half-moulds and inflating it. Immediately after the mould cavity wall is touched by the inflated parison, numerous needles are passed through the walls of the moulding from which they are retracted after the mouldings has cooled. Blowing air pressure is maintained during the cooling step. Dispenses with expensive, prior-art, drilling or otherwise perforating the moulding after it has cooled and been removed from the mould.