| 摘要 |
PROBLEM TO BE SOLVED: To smoothly demold a molded article by using an extrusion pin, in a demolding method for demolding a molded article by foamed sand from a mold.SOLUTION: A sand core W is molded by filling foamed sand S foamed by agitating a binder containing liquid glass along with aggregate in a cavity C of a mold 2 through a filling port 5 (A), to be solidified. Then, internal pressure is raised by heating, a dense hardened layer 17A is formed around the inside of the filling port 5, and a fragile part 18A is formed at the central part (B). The foamed sand S is filled in the filling port 5 again, and new hardened layers 17B, 17C and fragile parts 18B, 18C are formed inside the hardened layer 17A by solidifying the foamed sand (C), (D). The mold is opened, an extrusion plate 14 is lowered to insert an extrusion pin 15 in the filling port 5, and a hardened layer 17 is pressed to extrude the sand core W (E). By laminating and thickening the hardened layer 17, the hardened layer 17 can be pressed by the extrusion pin 15. |
