With preheating wire by resistance heat, laser hot wire welding improves process stability and wire deposition efficiency, which gives broad potential applications in sugracing and narrow gap welding. It is a critical...With preheating wire by resistance heat, laser hot wire welding improves process stability and wire deposition efficiency, which gives broad potential applications in sugracing and narrow gap welding. It is a critical issue to control the temperature of preheated wire in this process. The temperature which is so high that the wire fuses outside molten pool or so low that the wire cannot melt timely in the molten pool, results in poor wire transfer stability and bad weld formation. This paper is purposed to calculate the wire temperature for the prediction of wire transfer behavior under various welding parameters. A heat conduction model is set up. Heat sources of the wire include resistance heat and reflected laser, and the heat source of molten pool is laser. The calculated temperature of wire part outside the molten pool is verified by infrared ratio temperature measurement. The calculated temperature of wire part in the molten pool is verified by measurement of the molten pool size. Analyzing the wire temperature and welding process observed by the high speed video imaging, the temperature criteria of wire transfer behaviors are obtained. Thus, numerical simulation of the wire temperature can be used to predict wire transfer behaviors in laser hot wire welding.展开更多
导线温度监测是输电线路融冰过程的重要组成部分,为了克服输电线路温度监测需要现场电源,使用寿命短,容易受电磁干扰等缺点。本文基于光纤传感技术研制了FBG温度传感器以及设计了传感器夹具,该传感器采用双金属结构的方法实现温度增敏;...导线温度监测是输电线路融冰过程的重要组成部分,为了克服输电线路温度监测需要现场电源,使用寿命短,容易受电磁干扰等缺点。本文基于光纤传感技术研制了FBG温度传感器以及设计了传感器夹具,该传感器采用双金属结构的方法实现温度增敏;根据FBG对温度和应变的敏感特性,采用不受力的封装方式将其封装在外壳内,解决了温度与应变交叉敏感的问题。实验结果表明,研制的FBG温度传感器灵敏度为9.8 pm/℃,非线性误差0.79%,分辨率为0.102℃。收集整理云南电网某110 k V输电线路(2015年12月18日至2016年2月17日)的导线温度和环境温度监测数据,实现了对导线的监测。因此,基于光纤传感技术的输电导线温度监测可以被用来在线监测温度,为直流融冰等除冰过程提供数据支撑,以保障电网的安全运行。展开更多
A hot-wire gas metal arc welding （GMAIV） method using a TIG arc to preheat the wire was proposed and a corresponding experimental system was developed. The images of molten metal droplets in GMA W with thick-wire di...A hot-wire gas metal arc welding （GMAIV） method using a TIG arc to preheat the wire was proposed and a corresponding experimental system was developed. The images of molten metal droplets in GMA W with thick-wire diameter of 3.2 mm were captured by a high-speed camera, and the influence of the wire temperature on metal transfer was analyzed by measurements of droplet radius and transfer frequency. Two metal transfer modes were mentioned in this paper： the short- circuit transfer and the globular transfer mode. The results demonstrate that the wire temperature significantly impacts the metal transfer mode, droplet size and transfer rate at a certain welding current range. And with the increasing wire temperature, the change of metal transfer mode was observed. By increasing the temperature of the welding wire, the droplet size decreases and the droplet transfer frequency increases accordingly. In addition, it is important that the drop spray mode, which hardly occurs in GMAW with steel wire, was obtained by means of increasing the wire temperature.展开更多
This paper established the mathematical model of bridge wire temperature rise under direct current condition and gave the solution. It computed bridge wire temperature by using the thermal-electric coupling method pro...This paper established the mathematical model of bridge wire temperature rise under direct current condition and gave the solution. It computed bridge wire temperature by using the thermal-electric coupling method provided by ANSYS-Workbench finite element analysis software. In the end, the temperature bridge wire applied to different electric current was measured by the infrared thermal imaging temperature measurement method. The result shows that the ANSYS simulation results are in agreement with the theoretical calculation and the experimental results. It is feasible to compute bridge wire temperature of initiator by using ANSYS-Workbench software, and it is an important method to analyze complex structure of pyrotechnics.展开更多
基金This work was supported by the National Natural Science Foundation of China （Grant No. 51005125 ） and National Basic Research Program of China （Grant No. 2011CB013404）.
文摘With preheating wire by resistance heat, laser hot wire welding improves process stability and wire deposition efficiency, which gives broad potential applications in sugracing and narrow gap welding. It is a critical issue to control the temperature of preheated wire in this process. The temperature which is so high that the wire fuses outside molten pool or so low that the wire cannot melt timely in the molten pool, results in poor wire transfer stability and bad weld formation. This paper is purposed to calculate the wire temperature for the prediction of wire transfer behavior under various welding parameters. A heat conduction model is set up. Heat sources of the wire include resistance heat and reflected laser, and the heat source of molten pool is laser. The calculated temperature of wire part outside the molten pool is verified by infrared ratio temperature measurement. The calculated temperature of wire part in the molten pool is verified by measurement of the molten pool size. Analyzing the wire temperature and welding process observed by the high speed video imaging, the temperature criteria of wire transfer behaviors are obtained. Thus, numerical simulation of the wire temperature can be used to predict wire transfer behaviors in laser hot wire welding.
文摘导线温度监测是输电线路融冰过程的重要组成部分,为了克服输电线路温度监测需要现场电源,使用寿命短,容易受电磁干扰等缺点。本文基于光纤传感技术研制了FBG温度传感器以及设计了传感器夹具,该传感器采用双金属结构的方法实现温度增敏;根据FBG对温度和应变的敏感特性,采用不受力的封装方式将其封装在外壳内,解决了温度与应变交叉敏感的问题。实验结果表明,研制的FBG温度传感器灵敏度为9.8 pm/℃,非线性误差0.79%,分辨率为0.102℃。收集整理云南电网某110 k V输电线路(2015年12月18日至2016年2月17日)的导线温度和环境温度监测数据,实现了对导线的监测。因此,基于光纤传感技术的输电导线温度监测可以被用来在线监测温度,为直流融冰等除冰过程提供数据支撑,以保障电网的安全运行。
文摘A hot-wire gas metal arc welding （GMAIV） method using a TIG arc to preheat the wire was proposed and a corresponding experimental system was developed. The images of molten metal droplets in GMA W with thick-wire diameter of 3.2 mm were captured by a high-speed camera, and the influence of the wire temperature on metal transfer was analyzed by measurements of droplet radius and transfer frequency. Two metal transfer modes were mentioned in this paper： the short- circuit transfer and the globular transfer mode. The results demonstrate that the wire temperature significantly impacts the metal transfer mode, droplet size and transfer rate at a certain welding current range. And with the increasing wire temperature, the change of metal transfer mode was observed. By increasing the temperature of the welding wire, the droplet size decreases and the droplet transfer frequency increases accordingly. In addition, it is important that the drop spray mode, which hardly occurs in GMAW with steel wire, was obtained by means of increasing the wire temperature.
文摘This paper established the mathematical model of bridge wire temperature rise under direct current condition and gave the solution. It computed bridge wire temperature by using the thermal-electric coupling method provided by ANSYS-Workbench finite element analysis software. In the end, the temperature bridge wire applied to different electric current was measured by the infrared thermal imaging temperature measurement method. The result shows that the ANSYS simulation results are in agreement with the theoretical calculation and the experimental results. It is feasible to compute bridge wire temperature of initiator by using ANSYS-Workbench software, and it is an important method to analyze complex structure of pyrotechnics.
