Moulding flask for vacuum sealed moulding process

A molding flask for use in a vacuum sealed molding process comprising a frame having two openings disposed opposite to each other and closable by pattern plates covered by a shield membrane of synthetic resin which forms a mold surface;

• a pair of spaced impervious resilient membranes disposed between said two openings;
• a pair of spaced supporting means disposed between said pair of spaced membranes whereby each of the supporting means supports respectively each of the spaced membranes at the outside thereof, said spaced membranes and said supporting means dividing the interior of the flask into two parts;
• at least one opening disposed at each of said parts for supplying charging material into each of said parts;
• means for transmitting atmospheric pressure into the space between the supporting means whereby the outside of each spaced membrane is subjected to the atmospheric pressure;
• and at least one opening disposed at each of said parts for communicating with a vacuum source, said source being protected against ingressing of the charged material, and whereby said charged material in each of said two parts is subjected to reduced pressure.