Research on Dynamic Wear Process of Armature Surface in High-Speed Sliding Electric Contact

Armature is a key component of the electromagnetic launcher. During the dynamic launch process, its surface will be seriously worn, which will bring the following two problems: ① After the armature is worn and melted, it will form an aluminum layer in the bore, which will attach to the rail surface, increase the surface roughness, and affect the contact state between armature and rail during the subsequent launch process; ② After the tail is worn, the mechanical property that the armature can withstand is greatly weakened, which affects the launch safety. Therefore, it is of great significance to analyze the dynamic wear process of the armature surface in the high-speed sliding electrical contact process for controlling its surface wear, optimizing the armature structure, and improving the armature rail contact performance. First of all, by studying the physical process between the armature and rail during dynamic launch process, the results show that under the combined action of Joule heat and friction heat during the launch process, the armature surface temperature will rise sharply. Once it exceeds the material melting point, it will melt and cause wear. Therefore, the wear of the armature surface is caused by the combined action of electrical factors and force factors. Through the analysis of the muzzle armature X-ray photos in the early stage, it is concluded that the wear of the armature surface is not uniform from the tail end to the front end. In fact, the wear of the tail end of the armature is the largest, and the closer to the head, the smaller the wear is, which is approximately linear. On the basis of the above analysis results, taking into account the influence of surface wear changes, temperature rise and reverse force during the outward expansion of the armature tail, a theoretical calculation model for the wear of the armature tail is established, and its wear laws are studied. The average wear of the end of the armature tail is obtained. Then, the equal volume conversion method is used to convert the model into a linear wear model, and then the real wear of the end of the tail is obtained. The results show that:, After considering the influence of factors such as the change of surface wear amount, temperature and reverse force during the outward expansion of the armature tail, the analysis shows that the armature surface wear amount is 19.5% less than that when it is not considered, but it is closer to the measured value after considering, which proves that the above influence factors cannot be ignored in the analysis process. Finally, considering electromagnetic field temperature field stress field wear and other coupling factors, a three-dimensional finite element calculation model is established to more accurately analyze the wear amount of the armature tail, and the finite element is compared with the theoretical calculation results. The results show that the finite element model is more accurate than the approximate calculation method for the normal force component and reverse force of the armature tail in the theoretical analysis model, The calculated wear of the armature tail is closer to the measured value, which verifies the accuracy of the model. The model and analysis results established in this paper will help to optimize the armature structure, improve the contact performance between the armature and the rail, and ensure the safety of projectile launching in the bore. © 2023 Chinese Machine Press. All rights reserved.