When the mold shell of impeller investment castingpart and the sand mold of wheel hub and spoke part are prepared, the last process of molding – mold closing can be entered. Through this process, the impeller investment casting sand casting composite mold is obtained.
Impeller investment casting – the mold cavity and parting surface of sand casting mold shall be cleaned, and a circle of asbestos rope or mud strip shall be padded around the parting surface, core head and air outlet.
b. Lower core
Impeller investment casting –hub inner hole core places the sand core on the core seat of the lower mold through the core seat. The shell of the impeller investment casting sand casting part is connected with the sand mold cavity through the sodium silicate sand sleeve on the periphery of the shell Φ 973mm positioning circle.
c. Combination and verification
After the upper box is turned over, check whether there is damage, whether the air passage is unblocked, and whether the inner wall of the pouring riser is clean, and then close the upper and lower shapes together according to the locating pin. After closing, for the sake of safety, you can open it again to check whether there is crushing. In order to prevent fire escape during pouring, paste the gap of parting surface with sealing mud strip.
d. Put gate cup and paste box
After formal mold closing, put gate cup and riser ring at the position of upper mold pouring riser; In order to prevent fire escape during pouring, paste the gap of parting surface and around the pouring riser with sealing mud strip.
e. Fastening of mold
In order to counteract the box lifting force of liquid metal on the upper mold and prevent fire escape and floating box during pouring, the upper and lower molds are fastened by pressing iron before investment casting sand casting of impeller. When fastening the sand mold and pressing iron, in order to prevent crushing the sand mold or sand core, the gap shall be padded with iron sheets on the sand box at the four corners of the parting surface before fastening, so that the force on the sand box is uniform and symmetrical to prevent fire escape. At the same time, the pressing iron should be pressed on the sand box, not directly on the sand mold, so as to avoid box collapse.
The impeller investment casting sand casting composite mold obtained after mold closing is shown in the figure.