In terms of structure, due to the integrated structure, Jiangsu Yonghang Rail Transit Technology Co., Ltd. has improved the structural fatigue strength and high temperature fatigue life of materials in order to fully ensure the safe and reliable operation of the diesel engine, so as to meet the thermal load on the piston skirt. To meet the requirements of increasing mechanical load, improve the reliability of the use of the piston, the thin-walled rib-type iron skirt is adopted. We carry out mechanical analysis and calculation according to the thermal condition of the skirt during movement, and obtain the better wall thickness and stiffener of the iron skirt. , and then carry out a series of structural optimizations. Under the premise of fully meeting the required use requirements, the piston skirt is fully reduced in weight, and an effort is made to optimize the structure of the entire diesel engine.

In terms of material, the piston skirt material of Jiangsu Yonghang Rail Transit Technology Co., Ltd. adopts DIN standard and adopts high-strength ductile iron to obtain superior comprehensive mechanical properties and uniform metallographic structure.

In terms of technology, Jiangsu Yonghang Rail Transit Technology Co., Ltd. has carried out fine quality control in the process of piston iron skirt smelting, casting and heat treatment. Using advanced testing equipment to strictly control the whole process, we strictly test each casting heat and heat treatment. Considering the safety requirements of the piston skirt, we stipulate that the piston skirt has corresponding grades of surface defects and internal defects in different stress areas. The entire iron skirt is also processed by large-scale high-precision CNC to ensure the uniformity of wall thickness and surface quality during the processing. For the problem that the friction between the ductile iron piston ring groove and the piston ring is easy to wear and larger, Jiangsu Yonghang Rail Transit Technology Co., Ltd. fully absorbed the characteristics of the piston steel top quenching process, and we finally successfully selected the process parameters, which greatly extended the life of the iron piston after the ring groove hardening treatment. The roughness of the pin hole of the ductile iron piston skirt requires Ra0.8 , We designed and equipped with precision boring head and special boring tool, matched with reasonable process parameters, which well guaranteed the quality of pin hole cylindricity and roughness, and the actual measurement reached Ra0.8 um.

The surface-treated iron piston is subjected to graphitization of the skirt. For the iron piston skirt, the surface treatment is graphitized, and the graphite layer can reduce the initial wear of the engine. For the inner cavity surface, it can play a good anti-corrosion effect.