Numerical Simulation And Optimization Of Casting Process For QT450-10Bridge Box

The parts of inter-wheel differential on heavy duty truck are installed in the bridgebox,which is connected with the main reducer shell,so the bridge box bears large impactand vibration.In this paper,the casting process of nodular iron of sand mould castingwere designed and studied. The mould filling process and solidification process weresimulated by numerical simulation software.The possible types of casting defects andtheir forming reasons were analyzed in order to optimize the foundrytechnology.Finally,the casting defects were eliminated and the qualities of the bridgeboxes were improved.According to the structure characteristics and performance requirements of thebridge box,the original top gating casting process was put forward.The numericalsimulation of the mold filling and solidification process were proceeded byInteCAST.The simulation results showed that the mold filling process of the molten ironwas not smooth,so the gas and inclusions were easily involved into the molteniron.Because of that the thin-walled place of the bridge box solidified firstly,the flangeand thick bottom needed different risers for feeding,which caused low castingproduction rate and bad feeding effects.Serious shrinkage cavity and porosity wereformed at the flange and large bearing hole of the bridge box at the end of thesolidification,and the volume of the shrinkage cavity was4.42cc.The original top gating casting process was optimized by strengthening the feedingand improving the remaining liquid distribution of the casting.Adding blind riser withwent hole at the flange to reinforce the feeding and discharge the gas involved throughthe turbulence of the molten iron.Placing cold irons at the large bearing hole and thelarge lug boss to accelerate the solidification rate of the thick bottom.The shape and sizeof the open riser neck section were optimized and discovered that increasing the sizeappropriately would enhance the feeding capacity of the open riser,and the wide and flatshape of the open riser neck section was benefit for feeding.The best size and shape ofthe open riser neck section reduced the volume of the shrinkage cavity and porosity to1.42cc.The original bottom gating casting process was put forward to improve that topgating casting process couln’t eliminate shrinkage cavity and porosity. The simulationresults showed that the mold filling process was fast and smooth,and the solidification sequence from bottom to top was formed in the casting.Since the feeding duration of theriser was not long enough,a large independent liquid phase came into being,which wasresulted in a2.43cc shrinkage cavity.The original bottom gating casting process wasadjusted by changing the scale parameter of the riser and found that excessive height ofthe riser would draw the molten iron from the casting which increasing the volume ofthe shrinkage cavity and porosity instead of strengthening the feeding capacity.The bestscale parameter of the riser eliminated all the shrinkage cavity and porosity in thecasting.In this paper, an optimized casting process was schemed with shrinkage cavity andporosity eliminated completely by numerical simulation and process optimization,andimproved the casting production rate from45.9%to68.0%.