In terms of structure, due to the split structure, the steel top of the piston is designed as a self-supporting member, and the "drilling cooling" method is adopted to improve the rigidity and heat dissipation capacity of the piston head. The structural form is more and more widely used in the new four-stroke diesel engine. The worst place of the piston is at the top of the piston steel. Corrosive substances such as phosphorus and sulfur will continuously corrode the steel top of the piston. When the piston is repaired, it is only necessary to replace the steel top of the piston with a new one, and the lower skirt can continue to be used. In view of the continuous increase of the high explosion pressure of diesel engines, the split piston structure adopts high-strength bolts. Jiangsu Yonghang Rail Transit Technology Co., Ltd. uses the computer to simulate the force of the bolt during the reciprocating motion according to the characteristics of the reciprocating motion of the piston to determine the location of the maximum force. , and finally determine the design parameters of the bolt.
In order to fully ensure the safe and reliable operation of the diesel engine, the piston skirt Jiangsu Yonghang Rail Transit Technology Co., Ltd. has improved the structural fatigue strength and high temperature fatigue life of materials to meet the increasing thermal and mechanical load requirements of the piston skirt. , to improve the reliability of the use of the piston, the thin-walled rib-type iron skirt is used. We carry out mechanical analysis and calculation according to the thermal conditions of the skirt in motion, and obtain the better wall thickness and stiffener of the iron skirt, and then carry out a series of optimization procedures. , Under the premise of fully meeting the requirements for use, the piston skirt is fully reduced in weight, and its own efforts are made for the optimization of the entire diesel engine structure.
In terms of materials, Jiangsu Yonghang Rail Transit Technology Co., Ltd. uses high-quality A-grade heat-resistant alloy steel. From raw material procurement to processing to finished products, we strictly control and repeat the relevant parameters of the steel roof material in each link. detection. Piston skirt The material of the piston skirt of Jiangsu Yonghang Rail Transit Technology Co., Ltd. adopts DIN standard and adopts high-rank 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 strict quality control from the beginning of steel top forging. We attach great importance to each process, and we strictly control the equipment and parameters in each process. Repeated testing is carried out for each link. Steel top forging and heat treatment are the process elements that need to be controlled in the manufacturing process. Large-scale forging machines are used for steel top forging, and through precise die forging, the blank forging accuracy is guaranteed, the machining allowance is reduced, and good tissue fibers are obtained at the same time.
The entire processing of the steel top is completed by large-scale high-precision CNC, and the life of the steel top after the ring groove is hardened is greatly extended. In order to improve the traditional oscillating piston cooling method, Jiangsu Yonghang Rail Transit Technology Co., Ltd. is a piston steel The top provides a number of blind holes drilled radially obliquely outward from the central cooling surface. The number and arrangement of the holes and their effect on the temperature rise of the piston head are determined by calculation. The numerous blind holes on the piston head and the oil cavity on the thin-walled ductile iron skirt create a very large cooling cavity. With the help of the reciprocating motion of the piston, the exchange process of the cooling oil flowing in and out in the holes is improved, and the plate between the holes is effectively reduced. Compared with the traditional oscillating cooling cavity piston, the structural strength is greatly improved.
Piston iron skirt Jiangsu Yonghang Rail Transit Technology Co., Ltd. has carried out fine quality control in the process of 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 processing. In the process of fine boring pin holes of ductile iron piston skirts, the roughness of the pin holes of ductile iron piston skirts 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.