METHOD OF VACUUM MAKING THE UPPER HALF OF A MOULD WITH HORIZONTAL PARTING PLANE AND APPARATUS FOR REMOWING PATTERNS OF MAIN GATE AND STRAIN RELIEF FROM SUCH MOULD

摘要

An apparatus for forming a sprue and a communication hole in a vacuum-sealed mould. This method includes steps of: laying a shield film over a pattern and a sprue forming pattern or a communication hole forming pattern; assembling the pattern with a moulding flask; charging a charged material of particulate type into the moulding flask, and laying another shield film over the moulding flask, the charged material and the top portion of the sprue forming pattern or the communication hole forming pattern; welding the two films together along the periphery of the top surface of the sprue forming pattern or the communication hole forming pattern; cutting the two films, thus welded, along the periphery of the top surface of the sprue forming pattern or communication-hole forming pattern; and removing the sprue forming pattern or the communication hole forming pattern through the cut portion of the film. In addition, there is disclosed an apparatus for welding the two films together and cutting the same along the periphery of the top surface of the sprue forming pattern or the communication hole forming pattern.