| 摘要 |
PURPOSE:To prevent the mold collapsion arising from the decrease in the degree of vacuum by setting a pattern attracted with a film to a flask, packing molding sand into the flask, covering the top surface with a film and evacuating the inside of the flask then removing the film from the top surface in the projecting part of the pattern, providing a sleeve and building up additionally the molding sand into the flask thereby forming a casting mold. CONSTITUTION:The molding sand 4 is packed into the flask set with the pattern 1 having the projecting part 3 and having the film attracted thereto until the sand arrives at the top surface 3a in the projecting part 3 of the pattern 1. The top surface of the molding sand 4 and the top surface 3a in the projecting part 3 of the pattern 1 are coated with the film and the inside of the hermetic space formed of the molding flask and the film is evacuated. The film on the top surface 3a of the projecting part 3 of the pattern 1 is then partially removed and the sleeve 5 is provided so as to enclose the surface 3a. The sand 7 is added and built up so as to embed the sleeve 5 while an aperture 6 of the sleeve 5 is held open. The casting mold is thus formed. |
