Differential mechanism shell casting process

The invention provides a differential mechanism shell casting process which has the benefits that the hot section formation can be avoided, the shrinkage porosity and shrinkage cavity defects are overcome, the quality of castings is ensured, the large surface hardness fluctuation of a planet wheel machining spherical surface in contact with cold iron caused by the use of the cold iron is avoided, and the influence on follow-up machining is small; the drilling procedures are eliminated, and a rough boring-fine boring process is directly adopted, so that the cutting quantity is greatly reduced, and the processing efficiency is improved. The differential mechanism shell casting process comprises the following steps: 1, making a sand core main body (1) by adopting a core making machine, wherein the sand core main body (1) adopts an integral structure with a cast hole sand column (2) for casting a cross-shaped shaft hole in a differential mechanism shell; 2, drying the sand core main body (1) in the step 1; 3, putting the sand core main body (1) dried in the step 2 in upper and lower molds of the differential mechanism shell and then casting the molds according to conventional casting processes; 4, finally, opening the molds to obtain the differential mechanism shell (4) with the cross-shaped shaft hole.