Solidification numerical simulation and process optimization of Dia120mm wear resistant casting grinding ball (1)
(Electrical & Mechanical Repair Factory of Jinduicheng Molybdenum Group, Weinan 714102, Shaanxi China)
Abstract: Based on the original process, the simulation software developed by Visual C++ development tool has been adopted to numerically simulate the solidification process of
φ120 wear- resistant casting ball. By considering the numerical simulation results and theoretical analysis, in combination with actual production process optimization, the suitable process scheme has been finally obtained. The simulation result of the castings with improved process scheme shows that the process yield has been significantly improved.
Key words: φ120 wear resistant casting ball; Numerical simulation; Process optimization
Wear-resistant casting grinding ball is one of the two-pillar products of the mechatronics repair factory. The annual sales volume is 5500 tons, which accounts for 53% of the total output value for the whole year. At present, the 120mm diameter ball is produced by one mould four-ball metal mould casting process, and the yield rate of the process is about 80%. In the process of wear-resistant ball casting, the gating system’s parameters, such as the location and size of the runner, have a great influence on the yield and quality of the ball. Because of the casting process’s particularity, the casting quality can not be observed directly and can only be confirmed at the later stage. Therefore, the 120mm diameter ball casting system designed by the traditional method has a large safety factor, but the technological yield is low.
Therefore, in this paper, the simulation software of casting solidification process temperature field based on the Visual C + + development tool is used to simulate the solidification process of nodular cast iron, and the casting process scheme is improved according to the simulation results, the test results are in good agreement with the simulation results, and the technological yield of wear-resistant cast ball is increased successfully.
1.Analysis of previous casting process of casting grinding ball
1.1the previous casting process
The original casting process diagram of wear-resistant casting grinding ball is shown in Fig. 1. The project of one-type casting with multi-pieces and sand sleeve in the middle is adopted. The ratio of solidification time between runner and casting ball can be obviously increased by using a sand-jacket insulating runner, which is beneficial to the feeding of liquid metal to the casting ball in the runner, to increase the density of the casting ball, and to reduce the breakage rate of the casting ball in the ball mill, the service life of the metal mould can also be increased. In figure 1, T1 and T3 are located in the casting and mold, respectively, corresponding to T1 and T3 in the temperature measurement experiment.
The whole casting system includes casting, mould, and sand sleeves. The pouring temperature is 1350 °c, the room temperature, and the mold temperature are 20 °C. The three-dimensional modeling of castings, molds, and sand jackets and their assemblies are shown in figures 2,3,4 and 5.
The casting materials are ductile iron (C: 3.5% ~ 3.8% ; Si: 2.8% ~ 3.2% ; Mn: 2.1% ~ 2.4%) , and the casting materials are compacted graphite iron (C: 3.4% ~ 3.8% ; Si: 1.8% ~ 2.4% ; Mn: 0.3% ~ 0.6%) .