Thermal stress analysis in sand casting process

In sand casting production, hot cracks often occur due to structural reasons and improper process treatment of castings, or there is large residual stress or residual deformation in this part. This is a common defect in cast steel, which seriously affects the quality and service life of sand castings. These two kinds of defects are directly related to the generation and development of thermal stress during solidification, especially hot cracks, which generally occur in the quasi-solid region, And with the subsequent cooling of sand castings, the cracks continue to expand, often resulting in scrap of sand castings.

(1) This chapter studies the characteristics of thermal stress field and various processing conditions when using ANSYS to carry out numerical simulation of stress field. Indirect thermal stress analysis method is used for simulation using ANSYS. Through special processing of temperature field calculation, material mode, weighting coefficient of elastic-plastic transition zone, material performance at high temperature, interaction between sand casting and mold, calculation step length and grid division, etc, The simulation results of the three-dimensional transient stress field of the stress frame sand mold casting were successfully loaded and solved.

(2) The results of stress field simulation of stress frame show that during the whole solidification process of stress frame, the thin rod and thick rod of stress frame are subjected to dynamic stress respectively. At the initial stage of solidification, the thick rod is subject to compressive stress and the thin rod is subject to tensile stress: at some intermediate time, the thick rod and the thin rod are subject to the maximum compressive stress and tensile stress respectively; at the later stage of solidification, the thin rod gradually changes from tensile stress to compressive stress, while the thick rod gradually changes from compressive stress to tensile stress.

(3) The temperature field and stress field of the typical stress frame are analyzed by using ProCAST software, and the results are compared with the results of ANSYS, which shows that the change trend of the two software simulation results is basically consistent.

(4) The connection between ProCAST and ANSYS software is studied, which lays the foundation for realizing the connection between the two software.