| 摘要 |
PURPOSE:To obtain a master mold like a shell with safe stages at a low cost by charging molding sand contg. a gas hardenable additive into the spacing between a pattern plate and a molding flask and subjecting the same to compression molding and gushing treatments. CONSTITUTION:Molding sand 8 including a gas hardenable additive is charged into the delineating space between a pattern plate and a molding flask 7. A flexible film is put on the sand 8, and the inside of the sand 8 is evacuated to negative pressure by starting a vacuum pump 23 to mold the sand 8 by compression. Thereafter, the film is removed, and a cover member 24 communicating with a producing device 29 for a hardening gas is fitted airtightly to the upper part of the flask 7. The pump 23 is operated to conduct the hardening gas from the device 29 to the inside of the flask 7 and the inside of the sand 8 is sucked by the pump 23 to deodorize mold. The sucked gas is released into the atmosphere. In this stage the sand 8 is hardened by the hardening gas by which the master mold is formed. |
