Process Improvement Of Tight-lock Coupler Based On Numerical Simulation

Casting technology design is closely related to the casting solidification process, while casting solidification process is a complex process combined with high temperature, dynamic and transient changes and can not be directly observed. Although the theoretical system of casting filling and solidification process was established, it is difficult to describe casting solidification process and effectively guide the casting technology design. The traditional casting technology design depends mostly on experience and it needs try an error to improve the technology and eliminate defects. This method causes wastages of labor cost, material and time. With the development of computer technology, the defects caused during casting filling and solidification process can be predicted with the numerical simulation, and the casting technology can be effectively designed. As a result, the good quality of castings can obtained together with saving of manpower and time.Tight-lock coupler is a key connecting part in the train. It is very important for its quality to satisfy the safety requirement for running the train. There exists shrinkage defects in the tight-lock coupler produced by Sifang Locomotive and Rolling Stock Co., Ltd and the casting yield is low. Therefore it is necessary to improve its casting technology with the help of the numerical simulation so as to get good quality of castings and improve casting yield.Based on the cooperation project between Beijing Jiaotong University and Sifan Locomotive and Rolling Stock Co., Ltd.. the research presented in this paper is the solidification simulation of the tight-lock coupler castings to solve the shrinkage defects in production. 3D model of the casting is established with Pro / E code and the solidification of the casting process is simulated with ProCAST code. The main work focuses on the following:1 ) Measure the interfacial heat transfer coefficient between the castings and mold sand. The interfacial heat transfer coefficient is a significant factor and has an important affect on the numerical simulation accuracy. Through temperature measurement and under the condition of combination of the experiment with calculation results, the reasonable heat transfer coefficient can be obtained2 ) Improve casting technology design. Basing on the interfacial heat transfer coefficient obtained and by modifying and verifying simulation model of the existing technology to make simulation results consistent with actual measurement results, the reasonable casting technology was formulated with the help of the simulation to reduce the shrinkage defects in the castings. The simulation results of the improvement technology show that the metal liquid fills the mold smoothly and directional solidification can be achieved. The temperature field during solidification indicates that there was a good feeding path, so the shrinkage defects in castings can be eliminated with the casting technology.3) Increase the casting yield. Tight-lock coupler casting yield can be increased by 9% and the consumption of raw materials reduced and the economic benefits increased.