Abstract
Experiments have been performed to study the dimensional distortion in actual steel castings such as coupler yoke. The distortion was caused due to various factors including form of castings and condition of sand molds. Particularly, the form of castings had the most significant influence upon the distortion. As compared with this, the variations of mold condition and molding materials had less effects, even if either zircon sand or CO2 sand was employed for increasing the solidification rate and the rigidity of sand mold to resist the stress caused during casting, respectively. This is due to the fact that the distortion of castings is influenced more by the local differences in the rates of solidification and cooling than by those rates of the castings themselves. In order to make clear the phenomena of distortion, the author offers an assumption in which a casting is regarded as an assembly consisting of a number of units of a plane form and a simple box form. In this case, the plane form includes curved planes and the box form a cylindrical form. By using those assumptions it was able analytically to understand the distortion phenomena occuring in steel castings of a rather complicate form.
