METHOD FOR PREVENTING MOLD CRACK IN SHELL MOLDING

摘要

PURPOSE:To prevent over baking of a thin walled part and to prevent crack of a shell mold by coating shell sand on a metallic mold and baking the surface of the casting mold then coating a protective member to the thin walled part on the rear of the mold and baking the rear of the mold. CONSTITUTION:The metallic mold 2 for forming one surface of a dump type molding machine is heated to an adequate temp. and a dump box 3 is coupled thereto. A shutter 6 is opened to drop the shell sand 7 onto the mold 2, then the surface 8 of the casting mold is baked. The box 3 is turned 180 deg. to discharge the sand and after the shell mold 9 is formed on the mold 2, the shutter 6 is closed and again the box 3 is rolled over to restore the original attitude. The protective member 13 such as a wire net is coated on the thin walled part 12 at the corner part 10 of the mold 9 and the rear 15 of the mold is heated and baked by a heater 14 in a heating furnace 4. The above-mentioned part 12 dissipates heat quickly through the material 13, thereby preventing the over-baking and generation of the mold crack during pouring.