Synchronous staggered shooting of electric arc images and arc dynamics during polarity commutation
FU Pingpo, ZHU Zhiming, CHENG Shijia
Key Laboratory for Advanced Materials Processing Technology of Ministry of Education, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
Abstract:The synchronous acquisition and analysis of information about arc shape and current variations during the polarity commutation process of variable polarity tungsten inert gas (VP-TIG) arc welding are helpful to understand the arc dynamics mechanism. However, the polarity commutation process is relatively short, which leads to higher accuracy requirements for synchronous acquisition of the current information and arc image, as well as the acquisition frequency and image resolution of the image acquisition equipment. In this paper, the synchronous input and output functions of a data acquisition board were related to the synchronous trigger of a high-speed camera to realize synchronization acquisition of the welding current and arc image during polarity commutation with the synchronization error controlled to within 2 μs. In addition, use of the difference between the trigger voltage pulse and variable polarity periods enabled approximately continuous observation of the arc images with a lower acquisition frequency and higher image resolution, which reduces the camera speed requirement. The observations of the welding arc changes with the current showed that the arc shape variation lags behind the current change during the polarity commutation process and arc extinction does not occur at or around the time when the current value passes zero. In addition, the arc with the lowest gray level appears in the current recovery stage after the polarity commutation process. The results indicate directions for further improving the arc burning stability of VP-TIG arc welding.
[1] YAMADA R, UENAKA A, KATOHO T. Analysis of welding arc phenomenon with image processing[J]. Electric Furnace Steel, 2007, 78(2):115-121. [2] YANG M, ZHENG H, QI B, et al. Effect of arc behavior on Ti-6Al-4V welds during high frequency pulsed arc welding[J]. Journal of Materials Processing Technology, 2017, 243:9-15. [3] SHIGETA M, IKEDA T, TANAKA M, et al. Qualitative and quantitative analyses of arc characteristics in SMAW[J]. Welding in the World, 2016, 60(2):355-361. [4] HAO X F, SONG G. Spectral analysis of the plasma in low-power laser/arc hybrid welding of magnesium alloy[J]. IEEE Transactions on Plasma Science, 2009, 37(1):76-82. [5] YU H W, YE Z, CHEN S B. Application of arc plasma spectral information in the monitor of Al-Mg alloy pulsed GTAW penetration status based on fuzzy logic system[J]. The International Journal of Advanced Manufacturing Technology, 2013, 68(9-12):2713-2727. [6] XIE W C, JIANG W B, GAO Y Q. Spectral analysis of Ar plasma-arc under different experimental parameters[J]. Optik, 2013, 124(5):420-424. [7] 孙清洁, 林三宝, 杨春利, 等. 超声钨极氩弧复合焊接电弧压力特征研究[J]. 机械工程学报, 2011, 47(4):53-57, 65. SUN Q J, LIN S B, YANG C L, et al. Characteristic of arc pressure in ultrasonic-TIG hybrid welding[J]. Journal of Mechanical Engineering, 2011, 47(4):53-57, 65. (in Chinese) [8] 黄勇, 瞿怀宇, 樊丁, 等. 耦合电弧AA-TIG焊电弧压力测量与分析[J]. 焊接学报, 2013, 34(3):33-36. HUANG Y, QU H Y, FAN D, et al. Arc pressure measurement and analysis of coupling arc AA-TIG[J]. Transactions of the China Welding Institution, 2013, 34(3):33-36. (in Chinese) [9] 程林, 胡绳荪, 王志江. 变极性TIG焊电弧压力分析[J]. 焊接学报, 2014, 35(11):101-104. CHENG L, HU S S, WANG Z J. Arc pressure analysis in variable polarity TIG welding[J]. Transactions of the China Welding Institution, 2014, 35(11):101-104. (in Chinese) [10] 兰虎, 张华军, 陈善本, 等. 窄间隙MAG焊电弧声与电弧作用位置的相关性[J]. 机械工程学报, 2014, 50(24):38-43. LAN H, ZHANG H J, CHEN S B, et al. Correlation of arc sound and arc-sidewall position in narrow gap MAG welding[J]. Journal of Mechanical Engineering, 2014, 50(24):38-43. (in Chinese) [11] 刘立君, 周滨涛, 戴鸿滨, 等. 管道MIG焊双通道电弧声信号采集与特征分析[J]. 焊接学报, 2012, 33(8):41-44. LIU L J, ZHOU B T, DAI H B, et al. Dual-channel signal acquisition and characteristics analysis of arc sound in pipe MIG welding[J]. Transactions of the China Welding Institution, 2012, 33(8):41-44. (in Chinese) [12] 刘立君, 兰虎, 郑红艳, 等. MIG焊电弧声信号与熔透状态相关性[J]. 机械工程学报, 2010, 46(14):79-84. LIU L J, LAN H, ZHENG H Y, et al. Relationship between arc sound signal and penetration status in MIG welding[J]. Journal of Mechanical Engineering, 2010, 46(14):79-84. (in Chinese) [13] 陈茂爱, 吕云飞, 武传松. 基于LabVIEW的熔滴过渡过程参数检测系统的方案设计[J]. 山东大学学报(工学版), 2005, 35(6):103-107. CHEN M A, LÜ Y F, WU C S. A LabVIEW-based scheme for data acquisition system of metal transfer process[J]. Journal of Shandong University (Engineering Science), 2005, 35(6):103-107. (in Chinese) [14] 杨运强, 李桓, 李俊岳, 等. 熔化极电弧焊多信息同步高速摄影[J]. 焊接学报, 2002, 23(6):29-32. YANG Y Q, LI H, LI J Y, et al. High-speed photography with multi-information synchronizer for GMAW[J]. Transactions of the China Welding Institution, 2002, 23(6):29-32. (in Chinese) [15] 蒋元宁, 陈茂爱, 武传松. CO2焊电参数与熔滴过渡图像同步采集分析系统[J]. 焊接学报, 2013, 34(2):63-66. JIANG Y N, CHEN M A, WU C S. Synchronous acquisition and analysis of metal transfer images and electrical parameters in CO2 arc welding[J]. Transactions of the China Welding Institution, 2013, 34(2):63-66. (in Chinese) [16] 陈志翔, 张军, 宋永伦, 等. 焊接过程高速图像和工艺参数的同步记录与分析[J]. 焊接学报, 2010, 31(3):69-72, 76. CHEN Z X, ZHANG J, SONG Y L, et al. Synchronized record and analysis of high speed images and process parameters for welding process[J]. Transactions of the China Welding Institution, 2010, 31(3):69-72, 76. (in Chinese) [17] 李桓, 王俊红, 艾丹凤, 等. 弧焊过程中多信息同步采集系统[J]. 天津大学学报, 2012, 45(2):184-189. LI H, WANG J H, AI D F, et al. Synchronous multi-information acquisition system for arc welding process[J]. Journal of Tianjin University, 2012, 45(2):184-189. (in Chinese) [18] YANG Z Y, ZHU Z M, LIU B. Reverse voltage generating circuit for rapid commutation of output current polarity in variable polarity arc welding power supply[J]. IET Power Electronics, 2017, 10(12):1609-1616. [19] 杨中宇, 朱志明, 汤莹莹, 等. 稳压式变极性焊接电源二次逆变拓扑及控制策略[J]. 焊接学报, 2017, 38(9):23-27. YANG Z Y, ZHU Z M, TANG Y Y, et al. Topology of secondary inverter and its control strategy of variable polarity welding power supply for generating stabilized reverse voltage[J]. Transactions of the China Welding Institution, 2017, 38(9):23-27. (in Chinese)