Constraints on One-Piece C-Shaped Armature Tail Inclination in Electromagnetic Rail Launch
Chen Lixue1,2, Ren Ye1,2, Xu Shengqin1,2
1. State Key Laboratory of Advanced Electromagnetic Technology Huazhong University of Science and Technology Wuhan 430074 China; 2. Key Laboratory of Pulsed Power Technology Ministry of Education School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China
Abstract：Electromagnetic rail launch has the advantages of short launching time, fast launching speed, safety and reliability. Compared with traditional launching method, it has high current density and high relative motion speed, which is in a kind of extreme working condition. As the carrier of converting electric energy into kinetic energy, the working condition of the armature will be directly related to the working condition of the launcher. Compared with other solid armatures, one-piece C-shaped armature has a simple structure and is equipped with a functionally appropriate structure. On one hand, the tail can provide contact pressure, which ensures the electrical contact between the armature/rail; on the other hand, the armature tail inclination increases the friction between the armature and the rail to impede the armature motion, which in turn affects the armature motion characteristics, and in order to prevent the armature tail from fracturing, the tail inclination is also subjected to the armature mechanical strength. Therefore, selecting appropriate structural parameters of the armature tail in different launch scenarios is important to ensure the structural integrity of the armature, ensure the armature/rail electrical contact, and obtain a high launch speed. This article taken the straight armature as an example to study the value range of the tail inclination angle of the C-type armature: First, the lower limit of the value of the tail inclination was obtained based on the principle of armature acceleration, and the upper limit of the range was obtained based on the armature rail contact pressure requirement and the relationship between inclination and contact pressure; Secondly, the force analysis is carried out at the corner of the tail, and under the condition of ensuring that the tail will not break in the launching process, the implicit and explicit expressions of the values of the tail inclination are obtained according to whether the friction force in the launching process is neglected, and their results are compared to determine the range of values of the tail inclination under different current-carrying margin coefficients; Thirdly, the effects of the values of the tail inclination on the launch speed and rail length were obtained by the finite element simulation model, and the tail force curves and contact pressure margin curves were obtained for different values of the inclination. The following results were obtained: The critical value of the tail inclination decreases with the increase of current carrying margin factor in the interval 0.7~0.9, and tail inclination is not less than 13° in 30 mm caliber launcher, and is not less than 10° in 90 mm caliber launcher; To fully ensure the contact pressure demand during launch, the value of inclination ranges from 20° to 30°, at this time, the armature tail will not break during the launching process; At the same drive current waveform and the rated launch speed, the armature with a larger tail inclination is discharged earlier, and the required rail length is smaller. The rail length at 30° is 83% of that at 20°, and increasing the tail inclination significantly reduces the required rail length for launching.
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2025, Vol. 40 
