| 摘要 |
PURPOSE:To improve the surface roughness of a casting and to improve the permeability of a pattern by executing gas venting so that fine cracks develop in the suitable quantity at the time of drying coating agent and also forming the smooth surface of the pattern with small grains. CONSTITUTION:The coating agent 3 is dried after coating on the surface of the foaming pattern 4. Molten metal 2 is poured from a sprue and advanced while gasifying the pattern 4, and the produced gas 5 is discharged through the fine cracks 6 developed on the coating agent 3. The coating agent 3 is the one added with additive and solvent to binder of clag, etc., besides aggregate and kneaded and many cracks 6 are dotted on the dried surface. The condition of little quantity of moisture is developed near the aggregate having large grain size, and many fine cracks 6 are developed near the aggregate having much moisture dried latter on and small viscosity. By this method, the pattern coated with the coating agent improving the gas permeability is obtd. and gas deffect is eliminated and the workability coated on the pattern is improved because the ratio of the aggregate having small grain size is high. |
