PURPOSE: To prevent the generation of cavities in thick-walled parts and to improve productivity by providing a riser at the center and near the thick-walled parts of a mold which casts two pieces of differential cases facing each other, and communicating this with the thick-walled parts directly through ingates.
CONSTITUTION: A mold 22 casting two pieces of differential cases 21, 21' facing each other simultaneously consists of a drag 23, a cope 24, cores 25a, 25a, and a core 25b provided with a riser 32. Two pieces of the cases 21, 21' are so disposed as to align on the horizontal joint face B of the drag 23 and the cope 24. The above-mentioned riser 32 is communicated with the thick-walled parts 26 for bearings and flange parts 28 of both cases 21, 21' by means of ingates 31, 31' and further is communicated to riser 33 through an ingate 34 from an outside shell part 29, thick-walled parts 27 for bearings. Since the riser is provided near the thick-walled parts, the generation of cavities in the thick-walled parts is eliminated; hence, the reduction in the thickness, that is, weight, of the differential cases is made possible.
FUKAGAWA MASAYUKI
KUSAKA HIROARI
