Research And Simulation On Lost Foam Casting Moulding Process Of The Iron Casting

Lost foam casting is a near net shape technology with good prospects, which significantly reduces the production processes and costs. However, current LFC technology is not mature enough, which the numerical simulation technique to help design the lost foam casting process parameters is required. Casting Simulation technology plays a significant role in the actual production. Most companies choose France ESI's renowned ProCAST software. The filling & solidification simulation methods of iron lost foam casting with ProCAST have some problems that the fill and solidification are not in the same computational model. Moreover, in recent years many scholars have studied the causes and mechanism of lost foam casting's gating system, but there are not effective measures or methods to design it. Further aspects of current research on the growth of grains are still small, it can not effectively control the properties of castings. In this paper, combined with the Department of International Cooperation projects(ID: 2012DFG70640), research and simulation on lost foam casting moulding process of the iron casting, research results are as follows:By ladle analysis we obtain the composition of gray cast iron. By gray iron components and JMatPro software, we obtain the gray iron density curve. The iron of lost foam casting filling and solidification process is completed in a computational model. Compared with the experiment data and the plate part filling process simulation result of filling time, filling forms and the air gap can be accurately simulated; via the lift arms part solidification simulation result, the period of the liquid feeding and the expansion of the graphite can be drawn. the simulation result of the filling and solidification process of the iron lost foam casting, agree well with the actual situation of mold filling process and the shrinkage cavity.This paper presents a design method for feeding and gating system in lost foam casting process. Firstly, To obtain the field of chvorinov's thermal modulus by extracting and solving parameters(such as the field of temperature, alloy density at solidus, alloy enthalpy variation from alloy initial temperature to solidus etc) from the bearing pedestal simulation of solidification via ProCAST software. Secondly, according to the chvorinov's thermal modulus, method of Section ratio design and the proportional solidification theory, the size of feeding and gating system were designed quantitatively. The results indicate: The process of bottom gating system is suitable for the casting. Feeding and gating system is used to eliminate the hot spots at middle of the casting part. Extracting the average chvorinov's thermal modulus and the volumes of the metal liquid from solidification simulation results at the hot spots, the feeding size can be designed quantitatively; The filling results show that filling pouring rhythm should be " slow-fast-slow". The solidification results show that the liquid feeding Riser obviously. The pressure of graphitization expansion is not lost, which verifies that the casting process is ideal. The casting process parameters are used in the production and the production of gray cast iron meet the requirements.This article simulates grain nucleation and growth by Continuous nucleation model and KGT model. The parameters of ? and ? are calculated by KGT model and the characteristics of casting alloy. With the FEM result of thermal field at iron casting lost foam casting process extracted, the nucleation and growth process of grey iron solidification is simulated. The simulation results show equiaxed grains formed at the inside of the casting part fine grained region formed at surface area. The results of experiment and simulation show good agreement, which verifies that the simulation method is reasonable for both the grain nucleation and growth of grey iron in lost foam casting process..