鋳物砂の組合せ通気度およびそれと鋳肌粗さの関係

抄録

  An equation of the combined permeability of facing and backing sands is introduced and as its application, the relationship between permeability and surface roughness of castings was studied.
  Main conclusions obtained were as follows :
  1) The combined permeability of molding sands is calculated by the following equation
            [Written in non-displayable characters.].
      where H is height of each layer, K is permeability.
  2) The above equation can be applied extensively to values of the permeability with a good accuracy.
  3) The surface roughness of castings takes a minimum to a value of the combined permeability, which is changed by the mold surface or sand grain size, that is, with finer surface roughness of the mold the value declines to lower permeability. (Fig. 3) Therefore, in order to obtain fine surface roughness of castings, the combined permeability of facing and backing sands should be controlled properly according to mold surface roughness or sand grain size.