| 摘要 |
<p>PURPOSE:To obtain a mold for precision casting without any deformation at the time of pouring molten metal having high temp., by adding material developing volume expansion caused by MgO and chemical reaction at the time of molding the mold for precision casting with the material composing of MgO as main component and molding by kneading the above material with binder. CONSTITUTION:At the time of casting the precision casting, the investment material composing of 60-95wt.% MgO powder and powder expanding the volume caused by chemical reaction with MgO, for example <=25wt.% Ti powder, etc., and kneading with 0.5-5.0wt.% MgCl2 as the binder, is produced. Reverse shaped mold is made from the master pattern for the aimed precision casting, and the above investment material is flowed in this mold to make the pattern 1, and wax sheet 10 having 0.4mm thickness is stuck on the front face 3 of the pattern 1. This wax pattern 20 is laid in a forming flask 11 and then, the above investment material 13 is flowed in the forming flask 11. This is taken out, and heated in a heating furnace and thermal shrinkage of MgO is canceled by thermal expansion caused by the reaction with Ti and hardened, and at the same time, the wax sheet 10 is flowed out and the molten metal is cast by centrifugal force into the formed space 15 from a sprue 17 and the precision casting having excellent dimensional accuracy is improved.</p> |
