Abstract
The pressurizing mechanism of unbonded sand of the full mold process with reduced pressure was studied both theoretically and experimentally. Pressure distribution in sand was expressed theoretically by Jansen's equation in which the bulk density of sand and pressure coefficient evaluated from the experimentally obtained ratio of horizontal to vertical stresses were introduced. Some experiments were carried out with unbonded sand filled in a flask, 300mm square by 450mm deep, to verify the theoretical analysis. Surcharge of sand was effected by the use of either mold weights or reduced pressure, while pressure distribution was measured by pressure sensors installed at various. The theoretically predicted values agreed well with the experimental results. It was found that the pressure distribution changes remarkably with a change in the cross sectional area of the flask, due to the friction between sand and the flask wall.
