Background of pouring feature Design in Sand Mold casting

We will continue to explore the characteristic carbon benefit model of process design and the optimization and application of its parameters. Taking the pouring characteristics of a base casting as the research object, the casting is mainly used for the setting of roadblocks and road signs in road traffic. The basic shape of the casting is shown in figure 1. The casting is a small and medium-sized casting. The mass of each casting is 69.8820 kg, the casting material is HT250, and the maximum size of the casting is 400mm × 300mm × 182mm. The base of the casting is a plane, and one casting is made in each box. The size of the upper and lower sandboxes used is 310mm × 225mm × 250mm.

The important gating system in the gating characteristics will be studied. Through the analysis of the casting shape, the parameters of the initial gating system and riser will be designed according to the calculation method or look-up table method. The gating system adopts a semi-closed gating system, which has a certain slag blocking ability, which is suitable for all kinds of gray cast iron and ball castings, and is suitable for the base castings. The characteristic of the semi-closed gating system is that the cross-sectional area of each part of the gating system shows the following relationship: horizontal > vertical > inner. The cross section of the sprue in the formula represents the cross section of the sprue, the straight represents the cross section of the sprue, and the inside represents the cross section of the inner sprue. According to the size of the casting and the casting mode, the cross-sectional area ratio of process plan 1 is 1.256 / 1.4 / 1 in the range of cross-sectional area method. The cross-sectional area of blocking flow is the minimum size of the gate, and the cross-sectional area of the semi-enclosed gating system is on the inner gate. Through the look-up table method, it is found that the cross-sectional area of the casting is about 250mm2, so the cross-sectional areas of each part of the gating system are 314mm2, 350mm2 and 250mm2 respectively.

After ProCAST simulation, it is found that the internal defects are shown in figures 2 (An and B). The purple part indicates the defect of the casting, and the blue part indicates the incomplete part of the casting. The defect exists in the interior of the casting, and the use of post-processing will lead to huge carbon emissions and resource consumption, and the use value of castings will decrease. Therefore, according to the process design characteristics of the study, the pouring characteristics are improved. According to the analysis of the causes of the defects, the defects are mainly in the middle position and surface defects of the castings, the porosity of the internal structure of the castings must meet the requirements of constraints, and the surface defects can be removed by machining 1~2mm in a certain range.

According to the simulation results of ProCAST, in order to solve the internal shrinkage of the casting, a riser can be added to make up the interior of the casting, so as to eliminate the internal defects of the casting. The process parameters related to the gating characteristics are the structure of the gating system, the parameters of the riser and the pouring temperature. The process plan 1 is improved according to the empirical method, and a necking riser is added to the process parameters of the process plan 2.

The second process plan is re-simulated by ProCAST, and the simulation results show that the total shrinkage porosity and porosity of castings meet the quality requirements. Figure 2 shows the simulation results of total shrinkage porosity and casting porosity of FE2 (C and D). The result of the simulation is that the purple part of the casting disappears and FE2 improves the original internal defects. Due to the addition of risers, when the quality requirements are met, the process parameters of FE2 can be further optimized by the optimization method proposed in this paper.

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