高圧造型用ベントナイト系生型砂の水分添加量について

抄録

  It has been found that mold damages and swelling which occur in low pressure squeeze molding can be prevented by adding an excess of clay substance to the sand mixture. It the amount of clay substance can be decreased by means of high pressure molding, a denser and more uniform mold can be gained and the above mentioned mold defects can be prevented. This report is concerned with the method of determining the optimum moisture content of green sand mixtures for high pressure molding to minimize the clay content and stabilize the compaction properties, sand grain density, uniformity of grain density and permeability.
  The optimum moisture content for minimizing the clay content and stabilizing the compaction properties was obtained when the moisture/bentonite content ratio was about 3/7. Further, it was found to be important to choose the bentonite that showed the highest green tensile strength at the above ratio. The scattering of values of compaction properties and the spring-back property, owing to the changes in moisture and bentonite content, was minimized when the ratio of moisture/bentonite content was approximately 3/7.