| 摘要 |
PURPOSE:To make rapping easy in a casting mold of a metallic seal having a narrowed part in the top marginal part on the outside circumference by setting the diameter in the projecting part in the forming part a master mold for forming the narrowed part larger than the diameter in the projecting part of the upper step forming the narrowed part of the metallic seal after shrinkage on solidification. CONSTITUTION:A master mold 1 has a molding part having a narrowed part (a) for a metallic seal 4, a projecting part (c) for forming a projecting part (b) on the upper step thereof, and a recess (d) on the inside surface and a surface hole of a circular shape at the center on the top surface. The diameter of the part (c) of the molding part in the mold 1 is set larger than the diameter of the part (c) on the upper step forming the part (a) of the metallic seal after shrinkage on solidification. Therefore, if a bottom plate 3 is opened upon ending of shrinkage on solidification, the seal 4 is rapped easily in the direction F. |
