Press mould for thermoplastic television storage discs - with two separate heating and cooling circuits with spiral channels

摘要

The press mould comprises two separate heating and cooling circuits of which the channels are spiral and intercoiled. For feeding in opposite directions, the inlet of one spiral is at the edge of the press mould, and the inlet of the other is at the centre. Pref. the inlets and outlets of the two spirals are each located along a common radius line, and the two heating and cooling circuits, can be regulated separately. This arrangement allows the press mould to be simultaneously heated and cooled from the edge and from the centre of the mould, to provide a uniform temp. gradient over the whole surface are of the press mould. This prevents disadvantageous effects on the geometry of the body of the disc.