| 摘要 |
PROBLEM TO BE SOLVED: To smoothly exhaust gas generated from a lost foam pattern to out of a mold. SOLUTION: A pattern 1 composed of a losable synthetic resin foamed body is embedded into the mold and successively, the molten metal 8 poured from a sprue 2 is supplied into the upper part of the pattern 1 through runners 31, 32 and gates 4 and the pattern 1 is replaced into the molten metal 8 to produce a casting. At the time of using A for the total cross sectional area of the sprues 2, B for the total cross sectional area of the runners 32 and C for the total cross sectional area of the gates 4, these area have the relation of A<B<C. At least one side of the upper surface 321 of the runner 32 or the upper surface 41 of the gates 4, gas vent holes 51, 52 communicated with the air, are arranged. At the time of using D for the total cross sectional area of the gas vent holes 51, 52, these area are D<=A. |
