COMPACT FILLING METHOD OF GRANULAR SUBSTANCE FOR MOLDING

摘要

PURPOSE: To make the strength of a mold for molding uniform by introducing molding material into a molding device by plural stages of gas pressure surges. CONSTITUTION: The first pressure surge D1 is executed under a predetermined pressure P1 at a relatively flat boosting gradient. The air of the quantity carried in by the pressure surges flows through the volumetric body of sand and at least partially escapes from an air leading-out system arranged within a model mold plate. The volumetric body of the sand is sufficiently moved by the first pressure surge D1 and the nonuniformity having a possibility formed during the packing process is eliminated and made uniform in a model region, by which the uniform packing density in the model mold region is achieved. The subsequent second pressure surge D2 is executed on the molding mold material at the additionally higher boosting gradient. The second pressure surge D2 executes solid packing of the remaining sand height. The pressure applied at every time of the pressure surges D1 and D2 is in a region below the max. 20.4 Kg/cm<2> (20 bar). The pressure obtd. between both pressure surges D1 and D2 is always smaller than the pressure P1.