DYNAMIC MEASUREMENT AND FEM ANALYSIS OF RESTRAINT FORCE FROM MOLD ON GRAY CAST IRON CASTINGS AND CONTRACTION OF CASTINGS DURING COOLING IN GREEN SAND MOLD

摘要

The presence of residual stress and distortion are significant problems when producing sand castings such as cylinder heads and machine tool beds made from cast iron. Parkins identified these defects as caused by the restraint force from sand mold to casting [1]. In recent years, thermal stress analysis by FEM has been done against these defects. Until now, some researchers performed FEM analysis that incorporated the behavior of sand mold, and compared with experimented measurements. Baghani et al. (2014) has measured the residual stress on casting in sand mold, and compared with analysis results that used elasto-plastic constitutive equation for sand mold after shakeout [2]. However there is no previous research that evaluate the precision of analysis by continuously comparing the measurement from the end of the solidification process until the final cooling stage. In this study, firstly, we conducted a dynamic measurement of the restraint force from mold and the contraction of the gray cast iron in green sand mold. Then, we performed thermal stress analysis by taking account of the continuous behavior of sand mold. By comparing the analysis results with the experimental measurements, we verified the prediction precision of the restraint force from mold and the contraction of casting.