【作者】 郭韵；

【导师】 严仍春； 楼敏珠；

【作者基本信息】 机械科学研究总院 ， 测试计量技术及仪器， 2008， 硕士

【摘要】 在我国,由于火车制动粱端轴断裂造成的火车制动粱损毁和脱落一直是威胁列车行车安全的一大隐患。而目前对于端轴裂纹的检测,正常采用的磁粉探伤方法,检测工序复杂、需要工人长期肉眼观察裂纹,效率较低、容易造成因探伤人员工作疲劳而人为漏检。开发一种高效、方便探伤工人操作的火车制动粱端轴检测方法和仪器已成为提升列车运行安全性的重要举措。为此本文研究采用涡流检测技术检测端轴裂纹,着力于其关键技术的改进和优化开发,如:采用涡流阵列式探头扫查方式代替传统单探头旋转扫查方式,采用静态扫描方式简化机械装置和操作的复杂性并减小探头的提离从而提高检测精度,以及系统采用全新的涡流扫描彩色成像方式,能够对火车制动粱端轴的表面裂纹情况作直观的显示,图像插值处理提高成像质量等。1.在传统涡流仪器电路中引入扫描控制电路,通过多片差分模拟开关AD7502同单片机8051构成的扫描电路,实现对于16通道探头线圈的分时扫描。利用AD采集卡的开关量输入口同单片机的通信实现对于16通道涡流信号的扫描同步和位置同步。从而将单通道的涡流阻抗显示系统扩展成为多通道涡流检测成像系统。2.针对火车制动粱端轴的材料特性和裂纹分布情况采用数学模型分析和经验分析并用的方法,确定了线圈参数,并设计了涡流阵列式探头。16通道环型阵列式探头既有放置式探头对于表面裂纹检测灵敏度高等特点,又有阵列探头大面积扫查的优点。本文中采用逐个探头校准的方法,对于各个探头线圈进行了零电势和电感量的校准,在探头制作上最大限度地保证了阵列探头线圈的一致性,经过放大之后的剩余零电势采用软件补偿的办法,从而较好得解决了阵列探头的一致性问题。3.基于LabVIEW全新开发平台的开发扫描成像软件。实现了多通道数据的扫描同步和位置同步采集。通过IO控制卡,实现了设备参数控制。继承了传统涡流成像方式,包括并阻抗显示、XY幅值分量显示,并采用了全新的涡流C扫描彩色成像显示。4.此外,本文作者根据涡流信号的特点和处理的高效性设计数据处理算法,包括采用均线增量异常判断法快速地消除涡流信号中的异常值,实现数字信号滤波。采用模最大值压缩法实现对于数据压缩显示。引入伪彩色增强技术增强了涡流扫查成像信号幅值的分辨率,采用图像二维线性插值算法,通过快速的线性插值矩阵算法对于数字图像进行插值处理,消除了多通道图像之间颜色突变,提高了C扫描成像的质量。本研究不仅对于基于阵列式探头的涡流检测成像系统的进一步深入研究提供了参考,而且也为火车制动梁端轴裂纹的专用检测仪器的生产提供重要的技术基础。更多还原

【Abstract】 In our country, train brake braking and shedding caused by the cracks in brake beam axle is a hidden trouble to the safety of trains. Magnetic particle test used nowadays to inspect the cracks at beam axle is inefficient and with personal failure of defects report caused by the complicated testing procedure and long term defect viewing. So it is in urgent need of a new efficient, quick and easy operation testing method. For this reason, eddy current testing technique is used to test the cracks at beam axle in this paper with improvement and advance in some techniques such as: using eddy current array probe scan instead of single probe rotation scan for the reason that static scan has higher accuracy with shorter lift-off and simpler scan mechanical device than the single probe scan, using Pseudo color image display directly showing the crack in the surface of beam axle and using linear interpolation process to improve the quality of image. All these improve the ability of inspection cracks.1. Adding the scan circuit into the traditional eddy current instrument circuit, the multi-channel scan circuit which is built with several CMOS dual 4-channel analog multiplexer and Mod 8091 SCM achieves function of 16 channel probe coils shared-time scanning. In addition, the system collects data in scan synchronization and position synchronization based on the communication between data acquisition and SCM. The system is the production of upgrading an eddy current instrument to multi-channel eddy current imaging instrument. 2. Through the analysis of the object’s characters and its crack feature, by derivation the magnetic core pancake coil’s Impedance analytical expression and analysis from experience, coil’s character the coil’s parameters is determined and the array probe is produced. 16 channel eddy current array probe has both the advantage of high sensitivity of surface crack and large area quick scanning. The difference between the coils is eliminated to minimum by coil adjustment one by one. The software will subtract the residual voltage of the coil and solve this problem completely.3. The eddy current scan imaging software is designed based on the new LabVIEW platform. The software realizes the functions of parameters control through IO control card and inherits the traditional eddy current display including eddy current impedance and XY value display. However, the software have the new way of display like C-scan imaging display.4. In addition, the author designs the digital process algorithm according to the character of eddy current signal character and processing efficiency. The algorithm includes digital denoising based on the increment abnormity judge method and signal maximum compression. In image process, pseudo color technique is used to enhance the image vision resolution and the image interpolation process algorithm is designed to improve the image quality.The research in this paper provides not only the conference to further research of eddy current imaging system but also a technical fundament to develop the special instrument which is used in train brake beam axle crack inspection.更多还原