【作者】 路林；

【导师】 李英民； 常云龙；

【作者基本信息】 沈阳工业大学 ， 材料加工工程， 2014， 博士

【摘要】 钨极惰性气体保护弧焊（简称TIG焊）作为一种重要的焊接方法以其稳定的焊接电弧，优质的焊接成形，通用于各种金属连接，并属于非熔化极引弧过程无飞溅，但其电弧能量不集中，使得焊缝熔深浅（通常只能用于薄板焊接），焊接效率低等问题目前尚未得到圆满解决。焊接工作者针对其特点做了很多改进，如活性剂TIG焊、热丝TIG焊、超音频TIG焊等，然而其仍有其各自的局限性。如活性剂TIG焊的焊剂污染问题，热丝TIG焊不能用于铜、铝焊丝问题、超音频TIG焊的焊接电流小并且设备昂贵等问题。本文在阅读大量文献与前期大量实验的基础上，分析了TIG焊接电弧的特点，继而提出施加外加高频纵向磁场可以使电弧产生“压缩效应”，配合高频电流焊接设备更能提高焊接电弧能量，增大焊缝熔深的创新工艺；此种工艺附加装置成本低，体积小，使用方便，而且能够改善电弧形态与电弧行为。论文围绕这种新工艺主要进行了以下几方面的工作：论文提出一种电、磁双脉冲钨极氩弧焊接设备实现了大参数范围的电脉冲与磁脉冲共同作用，设备基本参数为：焊接电流0~500A；焊接电流频率：0~500Hz；激磁电流调节范围0~15A；激磁频率0~8kHz；占空比调节范围：50％；具有直流及交变方波输出功能。配备了与TIG焊焊枪配套的磁头结构。采用高速摄像对高频电、磁双脉冲控制下的电弧形态变化进行拍摄，通过光谱分析测定高频电、磁脉冲作用下的焊接电弧温度、利用自制环形同心裂极装置测定高频电、磁脉冲作用下电弧热量分布，采用探针法测试高频电、磁脉作用下电弧电流密度径向分布。实验结果表明：高频磁脉冲作用下焊接电弧旋转半径明显减小，形态由原来的锥形被压缩成为柱状，施加高频电路脉冲后电弧进一步被压缩。当焊接电流有效值为80A，电流脉冲频率为500Hz，磁感应强度为30mT，磁脉冲频率为1500Hz左右时，电弧温度由自由电弧时的13402.21K提升到14958.3K，热量分布系数从39.52%升高到66.07%，电弧压力与电流密度呈单峰分布，中心压力由0.35KPa增加到0.54KPa，电流密度由20A/mm2提高到30.9A/mm2。高频电、磁双脉冲作用下焊缝成形实验结果表明：高频电、磁脉冲作用使得焊缝成形良好，熔宽减小，熔深显著增大，且电流脉冲频率越大，效果越明显，而磁场却存在着一个最佳的参数范围。首次对高频电、磁脉冲作用下TIG焊电弧行为进行了理论分析，采用三维模型进行纵向磁场对焊接电弧温度场与流场分布计算。并建立高频磁场压缩焊接电弧的数学理论模型，系统解释高频磁场对焊接电弧气动压力变化规律（由环形双峰分布到柱形分布）为高频电、磁场控制TIG焊接过程提供新的研究思路。更多还原

【Abstract】 Inert gas shielded tungsten arc welding（TIG welding for short）,as an important weldingtechnology, has stable welding arc without any spatter and high quality which is in commonuse on kinds of metal connection. It belongs to gas metal arc welding, but the low welding arcenergy concentration makes low welding penetration (usually used only in thin plates welding)and and the low welding efficiency, which has not yet been satisfactorily resolved. Weldingworkers made many improvements, such as active flux TIG welding, hot wire TIG welding,ultrasonic frequency TIG welding and so on, but they have respective limitations. For example,the pollution problems of active flux TIG welding, hot wire TIG welding can’t be used incopper or aluminum wire, the welding current of ultrasonic frequency TIG welding is smallwith high device cost. Under the basis of many documents and large numbers of experiments,in this paper, the characteristics of TIG welding arc was analyzed, then imposed externalhigh-frequency longitudinal magnetic field on welding arc to produce “pinch effects”, whichcombined with high frequency current welding equipment could improve the welding arcenergy and increase welding penetration as an innovative processes. This technology withadditional device has low cost, small size, convenient use and can improve arc shape and arcbehavior. The paper around this new technology contains following works:The paper developed a electricity magnetism double-pulsed TIG welding controlequipment with electrical and magnetic pulse work together in range of adjustable parameters.The basic parameters as following: welding current:0~500A;welding current frequency:0~500Hz；magnetizing current adjustment range:0~15A; frequency of exciting current0~8kHz; duty ratio:50％,which has the function of direct and alternating square-wave output,equipped with a TIG welding torch head structure.A high-speed camera was used to obtain the changes of arc shape under the control ofhigh frequency electric pulse and magnetic pulse.A spectra measurement was used to measurearc temperature under high-frequency electro-magnetic pulse. Homemade ring concentriccracking device was used to measure arc heat distribution under high-frequencyelectro-magnetic pulse and the probe method was used to measure arc current density radialdistribution under high-frequency electro-magnetic pulse. Experimental results showed thatarc turning radius significantly reduced under high frequency Magnetic pulse, the arc shape changed from the cone-shaped to compressed columnar, the arc was compressed more withinhigh frequency current pulse. When the effective welding current was80A, current pulsefrequency was500Hz, the magnetic flux density was30mT, magnetic pulse frequency was1500Hz, arc temperature raised from13402.21K in free arc up to14958.3K, heat distributioncoefficient increased from39.52%to66.07%, the arc current pressure and density wereunimodal distributions, central pressure increased from0.35KPa to0.54KPa, current densityincreased from20A/mm2to30.9A/mm2.The welding experimental results under the effect of high-frequency electric andmagnetic double pulse showed that, the weld formation was well under high frequencyelectro-magnetic pulse, when melt width decreased, penetration increased significantly, andthe greater of current pulse frequency, the greater of the effect, and there was an optimumrange of parameters of magnetic field.It was the first time to analysis TIG welding arc behavior under high frequencyelectro-magnetic pulse, using a three dimensional mathematical model calculate arctemperature field and flow field distribution under vertical magnetic field. Then thecompressed arc mathematical model of high frequency magnetic field was constructed tosystemly explain arc air pressure variation law under high frequency magnetic field(from acircle bimodal distribution to a column-shaped distribution),and provided new research ideason TIG welding process within high-frequency electric and magnetic fields.更多还原