| 摘要 |
PURPOSE:To assure the accuracy of a mold by laminating gypsum in a fluid state as a surface layer on the mold surface of a prorotype model and fixing slit materials made of a synthetic resin foam to the mold surface then successively laminating the gypsum thereon after the prescribed time. CONSTITUTION:A base plate 11 is imposed and fixed atop a molding board 3 in such a manner that the mold surface 14 of the prototype model 1 faces upward. The gypsum in the fluid state is laminated to about 5mm thickness as the surface layer 24A on the mold surface 14 on which a parting material is preliminarily coated. The slit materials 26 formed of the urethane foam to a tape shape are then erected perpendicularly to the mold surface and are fixed at every 40mm intervals. The 2nd layer 24B is in succession laminated on the layer 24A upon lapse of about 30min and similarly the 3rd layer 24C is laminated thereon. Since the respective layers are divided by the slit materials 26 and are formed, the volumetric shrinkage by cooling of the gypsum is absorbed by the part of the materials 26. The required mold accuracy is thus assured.
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