Simulation study on the optimization of injection molding process for rubber ball joints used in high-speed trains

As a commonly used flexible connecting component in train bogies, the performance of rubber ball joints largely depends on the injection molding process. Based on the finite element method and SIGMASOFT ® software, this study simulated and analyzed the injection molding process of a typical rubber ball joint product (192 mm × 80 mm) using injection mold models with different numbers of gates (single/double) and vents (0/1/2). By constructing multiple comparative models, the effects of gate position, vent layout and injection pressure on the formation of weld lines and air entrapment, etc. During the molding process were systematically explored. The simulation results showed that the single-gate design could effectively reduce the generation of weld lines, with the length of weld lines being 13 mm less than that of the double-gate model. Compared with the number of vents, the position of vents had a greater impact on air entrapment. The air entrapment volume of the single-gate with 1 vent model was 3.7% less than that of the 2-vent model. When the injection pressure was set to 325 bar, the process scheme of single gate combined with 1 vent could achieve the highest product quality, characterized by the lowest internal defect rate and the optimal filling uniformity. These research results provided important theoretical basis and parameter references for optimizing the actual production process of rubber ball joints for high-speed trains.