Taking the tractor split sand casting axle housing as the research object, the axle housing is made of zg40mn low alloy cast steel. The water glass sand casting process is adopted. The filling, solidification process and casting defects of the axle housing are simulated and calculated by ProCAST computer simulation software. On this basis, the sand casting process of the axle housing is designed and optimized.
Three gating systems for sand mold casting are designed, which are closed gating system, open gating system and semi closed gating system. The numerical simulation software is used to simulate, analyze and compare three different gating schemes, and optimize the gating system. The results show that the semi closed gating system of scheme 3 has the best process, the least defects and high production efficiency. It is the best gating system for axle housing casting. The main conclusions are as follows:
(1) Analysis of the simulation results of mold filling flow field of the pouring system of sand casting axle housing shows that the sprue, transverse sprue and inner sprue are always in a full state, the melt flow in each sprue is smooth, without turbulence, no obvious churning phenomenon, and the slag blocking and slag retaining effect is good. Therefore, there are few casting defects such as sand holes and slag in the filling process of axle housing.
(2) It can be seen from the temperature field of the axle housing filling that there is no fluid phenomena such as cut-off and splashing during the metal liquid pouring process of sand mold casting, and the melt temperature has always been above the liquid phase temperature line. Therefore, it is very unlikely that the axle housing will produce casting defects such as cold lap, cold bean and insufficient pouring.
(3) The computer numerical simulation results of three initial pouring schemes of sand mold casting gating system show that shrinkage and porosity defects appear in the isolated liquid phase region during cooling. In the improved scheme I closed type and scheme III semi closed type, on the basis of the initial scheme, a riser is added at the front of the inner gate for feeding, three risers are added at the top for feeding, and six chills and one Chiller at the side of the inner cavity are added for quenching to achieve sequential solidification. The numerical simulation results show that, In the optimized pouring scheme, the shrinkage cavity in the axle housing of the three half closed pouring system completely disappeared and all of it was transferred to the riser, which played a good feeding effect, and the defects in the axle housing basically disappeared. Therefore, the semi closed gating system is the best casting process scheme of this research topic.