相控阵超声检测成像技术在耐张线夹压接质量检测的应用研究

“三跨”线路耐张线夹压接质量影响着电网运行安全,目前耐张线夹压接质量检测均存在一定的局限性,提出了基于相控阵超声检测技术的耐张线夹检测方法。首先对耐张线夹相控阵超声检测图谱进行了信号分析,证明相控阵超声成像技术可直观有效地检测耐张线夹漏压和欠压等压接质量缺陷。此外,为提高相控阵超声检测成像质量,分析成像影响因素,采用控制变量法研究线阵探头频率、孔径和焦距对耐张线夹相控阵检测成像的影响规律。研究发现：低频探头检测时耐张线夹检测信号会发生重叠,探头频率增大时,分辨力提高,但声波衰减增大,频率选择时要综合考虑对分辨力和灵敏度的影响;随探头孔径的增大,近场区长度增加,系统分辨力和灵敏度提高,但孔径增加受到工件外形尺寸的限制,一般选择孔径时应保证铝中的近场区长度不小于铝套管厚度和单根铝导线直径之和;聚焦区域的成像质量明显优于非聚焦区域,孔径变小时,焦点位置对检测结果的影响增大,检测时将焦距设置为铝套管厚度时检测成像效果最佳。研究结果对于相控阵超声成像在耐张线夹压接质量检测上的工程应用具有重要的参考价值。

Application Research of Phased Array Ultrasonic Testing in Quality Testing of Tension Clamp Crimping

The quality of the crimping of the tension clamp on the "three-span" line determines the safe and stable operation of the power grid. Due to the limitations of the current quality inspection techniques for compression of tension clamps, a method for inspecting tension clamps based on phased array ultrasound testing (PAUT) is proposed. Firstly, the PAUT signal analysis of the tension clamp was carried out, and it was proved that the phased array ultrasonic imaging technology can intuitively and effectively detect the crimp quality defects such as leakage pressure and undervoltage of the tension clamp. In addition, in order to improve the PAUT imaging quality and analyze the influencing factors of imaging, the control variable method was used to study the influence law of the frequency, aperture and focal length of linear array probes on the imaging of Tension clamp . The study found that the detection signal of the tension clamp will overlap at low frequencies. When the probe frequency increases, the resolution will increase, but the sound wave attenuation will increase. When selecting the frequency, the impact on the resolution and sensitivity should be considered comprehensively; as the probe aperture increases Large, the length of the near field area increases, the system resolution and sensitivity increase, but the increase in aperture is limited by the shape of the workpiece. Generally, when selecting the aperture, the length of the near field area in aluminum is not less than the thickness of the aluminum sleeve and the diameter of the single aluminum wire And; the smaller the aperture, the greater the effect of the focus position on the detection result. The imaging resolution of the focus area is better than that of the non-focus area. The detection imaging effect is best when the focal length is set to the thickness of the aluminum sleeve during detection. The results of the study have important reference value for the PAUT application in the quality inspection of crimping of tension clamps.