行波管典型焊接缺陷检测及评价技术研究

发布时间：2018-06-22 23:05

  本文选题：收集极 + 焊接缺陷　； 参考：《华南理工大学》2016年硕士论文

【摘要】：行波管作为一种用于放大信号功率的电真空器件,广泛应用于交通运输、工程建设、野外检测、手机通讯等领域。行波管在制造过程中需要使用大量异种金属焊接工艺。由于行波管工作环境恶劣,焊接质量欠佳的敏感结构易导致行波管工作失效。现今在行波管的生产过程中缺乏对其焊接缺陷的检测与评价,故本文通过对行波管内敏感焊接结构进行理论分析,开展了焊接缺陷的无损检测及评价技术研究,深入探讨了焊接缺陷产生的原因及机理,并对其焊接工艺提出优化方案。首先对行波管内敏感焊接结构及其焊接工艺进行理论分析,发现收集极焊接结构内焊接界面结合不良严重影响收集极散热,最终导致收集极烧毁。根据收集极的焊接结构特点开展超声探伤、3D X-ray检测技术研究,对焊接缺陷进行定性、定量分析,从而制定缺陷评定判据,即从收集极底座底面或侧面进行超声检测时,焊接界面回波波高分别超过屏幕范围的35%或40%时便可判定此处存在缺陷。通过ANSYS Workbench仿真分析与试验相结合的方式研究了焊接缺陷对收集极焊接结构热学性能的影响。焊接面积不足会导致收集极及焊锡层的温度上升,焊接面积分布不均同样会造成收集极温度过高,而当收集极与底座侧面和底面均存在焊接接触时收集极温度最低。当焊接接触面积低于50%时,收集极和焊锡层的温度会急剧上升,可能会造成焊锡层熔化流动,且焊接结构的热导率会大幅下降,从而阻碍收集极散热。故提出收集极与底座至少要有50%以上的面积存在焊接接触,且收集极与底座的侧面和底面均应有焊接接触的焊接质量要求。最后探讨了收集极焊缝内主要焊接缺陷产生的原因及机理,模拟仿真了现有焊接工艺下焊锡层的温度变化及分布情况,并结合焊缝内缺陷产生的原因,模拟计算了不同焊接工艺下焊锡层的温度变化及分布情况,从而给出焊接温度为270℃,焊接时间不少于320s的焊接工艺优化建议。
[Abstract]:As an electric vacuum device for amplifying signal power, traveling wave tube (TWT) is widely used in transportation, engineering construction, field detection, mobile phone communication and so on. A large number of dissimilar metal welding processes are needed in the manufacture of TWT. Because of the poor working environment of TWT, the sensitive structure with poor welding quality can easily lead to TWT failure. At present, the inspection and evaluation of the welding defects of TWT are lacking in the production process. Therefore, through the theoretical analysis of the sensitive welding structure in the TWT, the nondestructive testing and evaluation technology of the welding defects are studied in this paper. The causes and mechanism of welding defects are discussed, and the optimization scheme of welding process is put forward. Firstly, the sensitive welding structure and its welding process in traveling wave tube are theoretically analyzed. It is found that the poor bonding between the welding interface in the collector welding structure seriously affects the heat dissipation of the collector, and finally leads to the burning of the collector. According to the characteristics of the welding structure of the collector, the ultrasonic flaw detection 3D X-ray detection technology is studied, and the qualitative and quantitative analysis of the welding defect is carried out, so as to establish the defect evaluation criterion, that is, when the bottom or side of the collecting pole base is tested by ultrasonic, If the echo height of the welding interface exceeds 35% or 40% of the screen range, the defect can be determined. The influence of welding defects on thermal properties of collector welding structure was studied by ANSYS Workbench simulation and test. The temperature of the collector and solder layer will rise when the welding area is insufficient, and the temperature of the collector will be too high due to the uneven distribution of the welding area, and the temperature of the collector will be the lowest when there is welding contact between the collector and the side and bottom of the base. When the welding contact area is below 50, the temperature of the collector and solder layer will rise sharply, which may lead to the melting flow of the solder layer, and the thermal conductivity of the welding structure will decrease significantly, thus hindering the collection pole heat dissipation. Therefore, it is suggested that at least 50% of the area between the collector and the base should have welding contact, and the welding quality requirement of welding contact should be required for the side and bottom of the collector and the base. Finally, the causes and mechanism of the main welding defects in the collector weld are discussed, and the temperature change and distribution of the solder layer under the existing welding process are simulated, and the causes of the defects in the weld are combined. The temperature variation and distribution of the solder layer under different welding processes are simulated and calculated, and the optimization suggestions for welding process with the welding temperature of 270 鈩，

本文编号：2054599