| 摘要 |
PURPOSE: To obtain a core metal tool excellent in the durability by forming a mold with a formed graphite having the specific bulk density, resistibility, hardness, strength, coefficient of thermal expansion, thermal conductivity and max. grain diameter. CONSTITUTION: Molten low alloy steel is poured from a molten metal sprue 4 into the mold having a space 3 assembling a core and a holding mold 2 in the formed graphite mold 1 and the cast steel is taken out from the mold. The formed graphite mold 1 is formed of the formed graphite having 1.6-1.8 bulk density, 6.5-11.0μΩm restibility, 18-55 Shore hardness, 8-40MPA bending strength, 15-80MPA compressive strength, 5-25MPA tensile strength, 2.5-5×10<-6> K coefficient of thermal expansion, 110-160W/(m.k) thermal conductivity and <=3mm of the max. grain diameter at ordinary temp. as the characteristics. By this method, number of piercing can drastically be increased.
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