技术领域technical field
本发明属于无损检测技术领域，具体涉及一种适用于金属板件表面缺陷高效检测和定位的微波检测探头和相应的缺陷定位方法。The invention belongs to the technical field of non-destructive testing, and in particular relates to a microwave detection probe suitable for efficient detection and positioning of surface defects of metal plates and a corresponding defect positioning method.
背景技术Background technique
金属板件广泛应用于人类的生产生活当中，尤其是在一些核心和关键的机械结构中。飞机机身是缺陷经常发生的地方。从早期检测角度来看，对早期金属板件表面的缺陷检测是很有必要的。常规的涡流检测方法需要逐点扫描，对人力和财力都有很高的要求，代价极大。其他无损检测方法，如漏磁法，红外热成像法等效率低下，超声检测需要耦合介质比较麻烦。微波检测具有不接触检测物体，穿透介电材料等特性。这使得微波在金属板件表面缺陷检测上具有独特的优势。Sheet metal parts are widely used in human production and life, especially in some core and key mechanical structures. Aircraft fuselages are where defects often occur. From the perspective of early detection, it is necessary to detect defects on the surface of early sheet metal parts. Conventional eddy current testing methods require point-by-point scanning, which requires high manpower and financial resources, and is extremely costly. Other nondestructive testing methods, such as magnetic flux leakage and infrared thermal imaging, are inefficient, and ultrasonic testing requires a coupling medium, which is troublesome. Microwave detection has the characteristics of not touching the detection object and penetrating dielectric materials. This makes microwave have a unique advantage in detecting surface defects of sheet metal parts.
虽然学者们早在20世纪70年代就开始了微波检测的研究。但是直到近年，才出现使用带金属法兰的矩形波导进行近场检测的研究。最近，掀起了一阵采用开放式同轴传感器微波探头检测裂纹的研究热潮，这种探头灵敏度极高，甚至能检测出闭合裂纹。研究者不仅将其应用到近场检测金属板件表面缺陷，还将其应用到远场管道裂纹、管壁减薄、微生物识别的检测、定位和定量评估中。将管道看作圆形波导管，向圆形波导管中发射微波信号，圆形波导管内壁表面存在电流。当管道出现缺陷，缺陷阻碍波导管内壁表面电流流动，波导管内壁电流的变化引起管道内的电磁波的变化，探头接收到的电磁波信号携有与缺陷有关的信息。由于微波可以在波导管中传输很长一段距离，且衰减较少。故上述方法能够大范围地检测金属管道内表面缺陷。Although scholars started research on microwave detection as early as the 1970s. But until recent years, the use of rectangular waveguides with metal flanges for near-field detection has not appeared. Recently, there has been a wave of research to detect cracks using open coaxial sensor microwave probes, which are extremely sensitive and can even detect closed cracks. The researchers not only applied it to the near-field detection of surface defects of sheet metal parts, but also applied it to the detection, location and quantitative evaluation of pipe cracks, pipe wall thinning, and microbial identification in the far-field. The pipe is regarded as a circular waveguide, a microwave signal is emitted into the circular waveguide, and a current exists on the inner wall surface of the circular waveguide. When there is a defect in the pipeline, the defect hinders the flow of current on the surface of the inner wall of the waveguide, and the change of the current on the inner wall of the waveguide causes the change of the electromagnetic wave in the pipeline, and the electromagnetic wave signal received by the probe carries information related to the defect. Because microwaves can travel a long distance in waveguides with less attenuation. Therefore, the above method can detect defects on the inner surface of metal pipes in a wide range.
发明内容Contents of the invention
为了提高微波检测金属板件的效率，本发明提出了一种金属板件表面缺陷检测和定位的微波检测探头及方法，利用该微波检测探头可以实现金属板件表面缺陷的检测和定位，鉴于国内对微波检测金属板件表面缺陷方法尚不完善，本发明提出微波检测探头具很强的实用性和较高的工程应用价值。In order to improve the efficiency of microwave detection of sheet metal parts, the present invention proposes a microwave detection probe and method for detecting and locating surface defects of sheet metal parts. Using the microwave detection probe, the detection and positioning of surface defects of sheet metal parts can be realized. In view of domestic The method for microwave detection of surface defects of metal plates is not yet perfect, and the microwave detection probe proposed by the present invention has strong practicability and high engineering application value.
为了达到上述目的，本发明采用如下技术方案：In order to achieve the above object, the present invention adopts following technical scheme:
一种金属板件表面缺陷检测和定位的微波检测探头，包括底边相等为l、高度为h、无底面的长方体金属盒型的金属罩1，其中0<h≤l，，固定在探头金属罩1相邻两侧面的两只相同的射频同轴连接器，分别为x方向对应的第一射频同轴连接器T和y方向对应的第二射频同轴连接器D。A microwave detection probe for detecting and locating surface defects of a metal plate, comprising a cuboid metal box-shaped metal cover 1 with a base equal to l, a height h, and no bottom, wherein 0<h≤l, fixed on the probe metal The two identical RF coaxial connectors on adjacent two sides of the cover 1 are the first RF coaxial connector T corresponding to the x direction and the second RF coaxial connector D corresponding to the y direction.
所述探头金属罩1是由电导率不小于4.10×107S/m的金属材料制作。The probe metal cover 1 is made of a metal material with an electrical conductivity not less than 4.10×107 S/m.
所述探头金属罩1内壁上镀金或银。The inner wall of the probe metal cover 1 is plated with gold or silver.
在探头金属罩1相邻的两个l×h侧面中心分别固定两个相同的射频同轴连接器。Two identical RF coaxial connectors are respectively fixed at the center of the two adjacent l*h side surfaces of the probe metal cover 1 .
所述第一射频同轴连接器T和第二射频同轴连接器D是母转公连接器，公头在探头金属罩1内侧，母头在探头金属罩1外侧，用于连接同轴线电缆。The first RF coaxial connector T and the second RF coaxial connector D are female-to-male connectors, the male head is inside the probe metal cover 1, and the female head is outside the probe metal cover 1 for connecting the coaxial cable cable.
所述微波检测探头一次性检测金属板件区域为l×l。The microwave detection probe can detect the area of the metal plate at one time to be 1×1.
探头上金属罩的设计使得在检测时，微波信号集中在微波检测探头和待测金属板件组成的矩形波导管中传播，提高了检测效率和灵敏度。The design of the metal cover on the probe makes the microwave signal concentrated in the rectangular waveguide composed of the microwave detection probe and the metal plate to be tested during detection, which improves the detection efficiency and sensitivity.
所述的微波检测探头进行金属板件表面缺陷检测和定位的方法，具体步骤如下：The method for detecting and locating the surface defect of the metal plate with the microwave detection probe, the specific steps are as follows:
1)搭建实验系统，微波矢量网络分析仪和同轴线电缆一端连接，同轴线电缆另一端与第一射频同轴连接器T和第二射频同轴连接器D连接；微波检测探头固定在探头支架上，探头支架能够在x、y、z三个方向移动；为了消除仪器对测量结果的影响，测量前需要对仪器进行电校准，保证微波检测探头上的两只射频同轴连接器公头为零基准面；在标准金属板件上，对微波检测探头进行群速度校准；1) Build an experimental system, connect the microwave vector network analyzer to one end of the coaxial cable, and connect the other end of the coaxial cable to the first radio frequency coaxial connector T and the second radio frequency coaxial connector D; the microwave detection probe is fixed on On the probe bracket, the probe bracket can move in the three directions of x, y, and z; in order to eliminate the influence of the instrument on the measurement results, the instrument needs to be electrically calibrated before measurement to ensure that the two RF coaxial connectors on the microwave detection probe are The head is the zero reference plane; on the standard metal plate, the microwave detection probe is calibrated for group velocity;
2)移动探头支架到位置(X,Y)，检测区域为[X‐l/2,X+l/2]×[Y‐l/2,Y+l/2]；在z方向上移动探头支架，将微波检测探头紧贴在金属板件表面，这样探头金属罩1和待测金属板件构成矩形波导管；2) Move the probe holder to the position (X, Y), the detection area is [X‐l/2, X+l/2]×[Y‐l/2, Y+l/2]; move the probe in the z direction A bracket, the microwave detection probe is closely attached to the surface of the metal plate, so that the probe metal cover 1 and the metal plate to be tested form a rectangular waveguide;
3)微波矢量网络分析仪通过同轴线电缆和微波检测探头上的第一射频同轴连接器T给微波检测探头提供微波信号，使微波在探头中沿x方向传播，微波矢量网络分析仪在第一射频同轴连接器T中检测反射的微波信号；3) The microwave vector network analyzer provides microwave signals to the microwave detection probe through the coaxial cable and the first radio frequency coaxial connector T on the microwave detection probe, so that the microwave propagates along the x direction in the probe, and the microwave vector network analyzer Detecting reflected microwave signals in the first radio frequency coaxial connector T;
4)通过反傅立叶变换，计算得出时域信号；若时域信号在矩形波导管终端产生的反射峰Tend时刻前不存在明显的反射波峰，移动探头到下一个检测位置，重复步骤2)‐4)，继续金属板件表面缺陷的检测，直至完成全部待检测区域的检测；若在微波终端反射峰Tend时刻前存在明显的反射波峰，采用校准后的群速度确定缺陷的相对横坐标xr；4) Calculate the time-domain signal by inverse Fourier transform; if there is no obvious reflection peak in the time-domain signal before the reflection peak Tend generated by the terminal of the rectangular waveguide, move the probe to the next detection position and repeat step 2) ‐4), continue to detect the surface defects of the metal plate until the detection of all the areas to be detected is completed; if there is an obvious reflection peak before the microwave terminal reflection peak Tend time, use the calibrated group velocity to determine the relative abscissa of the defect xr ;
5)微波矢量网络分析仪通过同轴线电缆和微波检测探头上的第二射频同轴连接器D给微波检测探头提供微波信号，使微波在探头中沿y方向传播，在第二射频同轴连接器D中检测反射的微波信号；5) The microwave vector network analyzer provides microwave signals to the microwave detection probe through the coaxial cable and the second radio frequency coaxial connector D on the microwave detection probe, so that the microwave propagates in the probe along the y direction, and the second radio frequency coaxial The reflected microwave signal is detected in the connector D;
6)通过反傅立叶变换，计算得出时域信号；观察时域信号在矩形波导管终端产生的反射峰Tend时刻前的显著波峰，通过这个显著波峰时刻确定缺陷的相对纵坐标yr；6) Calculate the time-domain signal through inverse Fourier transform; observe the significant peak of the time-domain signal before the reflection peak Tend time generated by the terminal of the rectangular waveguide, and determine the relative ordinate yr of the defect through this significant peak time;
7)采用公式x＝X+xr‐l/2,y＝Y+yr‐l/2计算，最终确定缺陷在被测金属板面上位置。7) Use the formula x=X+xr -l/2, y=Y+yr -l/2 to calculate, and finally determine the position of the defect on the surface of the metal plate to be tested.
检测时，针对检测缺陷的方向选择合适的主导模式微波，其中，TE波主导模式微波检测平行于微波传输方向的缺陷灵敏度高，TM波主导模式微波检测垂直于微波传输方向的缺陷灵敏度高。During detection, select the appropriate dominant mode microwave for the detection direction of the defect. Among them, the TE wave dominant mode microwave has high sensitivity to detect defects parallel to the microwave transmission direction, and the TM wave dominant mode microwave has high sensitivity to detect defects perpendicular to the microwave transmission direction.
根据微波检测探头的尺寸和主导模式微波、检测灵敏度确定检测波的频率范围，通过微波矢量网络分析仪控制检测波的频率范围。The frequency range of the detection wave is determined according to the size of the microwave detection probe and the dominant mode microwave and detection sensitivity, and the frequency range of the detection wave is controlled by a microwave vector network analyzer.
和现有技术相比，本发明具有如下优点：Compared with the prior art, the present invention has the following advantages:
本发明设计的微波检测探头利用金属罩将微波全部限制在金属罩和待测金属板件组成的矩形波导管中，使微波在矩形波导管中传播。微波在金属罩和待测金属板件组成的矩形波导管传输时，微波在矩形波导管腔中传播，矩形波导管内壁表面存在电流，这样检测到的微波信号携带有与金属板件表面缺陷有关的信息。与传统微波检测金属的探头相比，如同轴探头、带金属法兰的矩形波导探头、带金属法兰的开放式同轴线传感器探头，这种封闭式探头将微波的传播全部集中在了高电导率金属罩和待测金属板件组成的矩形波导管中，提高了检测效率和灵敏度。该微波检测探头结构简单，检测对象广，检测便捷，检测效率高，检测精度高。微波检测探头对金属板件的检测时，只要让微波检测探头紧贴在金属板件需要检测区域的表面，就可以进行缺陷检测。该微波检测探头可以对任意形状的无孔洞的平面金属板件的表面缺陷检测和定位。检测时，只需要保持待检测金属板件表面清洁，将微波检测探头紧贴在金属板件上，微波矢量网络分析仪通过同轴线电缆和同轴射频连接器发射和接收信号，即可实现对金属板件表面缺陷的检测和定位。采用这种新型的微波检测探头检测，一次性检测平面金属板件区域面积是l×l。检测时，微波集中在微波检测探头和待测金属板件组成的矩形波导管中传播，具有较高的检测效率和灵敏度。The microwave detection probe designed in the present invention uses a metal cover to confine microwaves in a rectangular waveguide composed of the metal cover and the metal plate to be tested, so that the microwaves propagate in the rectangular waveguide. When the microwave is transmitted in the rectangular waveguide composed of the metal cover and the metal plate to be tested, the microwave propagates in the cavity of the rectangular waveguide, and there is a current on the inner wall surface of the rectangular waveguide, so that the detected microwave signal carries a signal related to the surface defect of the metal plate. Information. Compared with traditional microwave metal detection probes, such as coaxial probes, rectangular waveguide probes with metal flanges, and open coaxial sensor probes with metal flanges, this closed probe concentrates the propagation of microwaves in the In the rectangular waveguide composed of the high-conductivity metal cover and the metal plate to be tested, the detection efficiency and sensitivity are improved. The microwave detection probe has the advantages of simple structure, wide detection objects, convenient detection, high detection efficiency and high detection precision. When the microwave detection probe detects the metal plate, as long as the microwave detection probe is close to the surface of the metal plate to be detected, the defect detection can be carried out. The microwave detection probe can detect and locate the surface defect of a flat metal plate with any shape and no holes. When testing, it is only necessary to keep the surface of the metal plate to be tested clean, stick the microwave detection probe to the metal plate, and the microwave vector network analyzer can transmit and receive signals through the coaxial cable and the coaxial RF connector to realize Detection and localization of surface defects on sheet metal parts. Using this new type of microwave detection probe for detection, the one-time detection area of the flat metal plate is l×l. During detection, the microwaves are concentrated in the rectangular waveguide composed of the microwave detection probe and the metal plate to be tested, which has high detection efficiency and sensitivity.
附图说明Description of drawings
图1为微波检测探头的立体图。Fig. 1 is a perspective view of a microwave detection probe.
图2为微波检测探头的主视剖视图。Fig. 2 is a front sectional view of the microwave detection probe.
图3为微波检测探头的左视剖视图。Fig. 3 is a left sectional view of the microwave detection probe.
图4为微波检测探头俯视剖视图。Fig. 4 is a top sectional view of the microwave detection probe.
图5为微波检测探头前侧面前视图。Fig. 5 is a front view of the front side of the microwave detection probe.
图6为微波检测探头前侧面后视图。Fig. 6 is a front side rear view of the microwave detection probe.
图7为微波检测探头右侧面右视图。Fig. 7 is a right view of the right side of the microwave detection probe.
图8为微波检测探头右侧面左视图。Fig. 8 is a left side view of the right side of the microwave detection probe.
图9为自主设计的微波检测探头对金属板件表面缺陷检测和定位示意图。Fig. 9 is a schematic diagram of the self-designed microwave detection probe for detecting and locating the surface defects of the metal plate.
图10为微波检测探头在金属板件表面移动检测缺陷的示意图。Fig. 10 is a schematic diagram of a microwave detection probe moving on the surface of a metal plate to detect defects.
具体实施方式Detailed ways
下面结合附图对本发明的内容作进一步详细说明。The content of the present invention will be described in further detail below in conjunction with the accompanying drawings.
微波检测探头的设计和检测方法：Design and detection method of microwave detection probe:
如图1‐8所示，本发明设计的在电导率不小于4.10×107S/m金属材料制作的金属罩1(金属罩1的形状是底边相等无底面的长方体金属盒型)相邻的两个l×h侧面上固定两只射频同轴连接器的一种新型的微波检测探头。探头金属罩1由电导率不小于4.10×107S/m的金属材料制作，由于微波在波导管传输时，微波在波导管中传播，波导管内壁表面存在电流，与波导管本体材料基本无关，可在探头金属罩1内壁上镀金或银，这样减少微波传输过程中的损耗。内壁镀金或银金属罩的形状是底边相等无底面的长方体金属盒型，金属罩长l、宽l、高h(0<h≤l)。在金属罩1相邻的两个l×h侧面中心分别固定两个相同的射频同轴连接器，分别为第一射频同轴连接器T和第二射频同轴连接器D。这两只射频同轴连接器是母转公连接器，它们的公头在探头金属罩1内侧，母头在探头金属罩1外侧。As shown in Figure 1-8, the metal cover 1 (the shape of the metal cover 1 is a rectangular parallelepiped metal box with equal bases and no bottom) designed by the present invention is made of metal materials with an electrical conductivity not less than 4.10×107 S/m. A new type of microwave detection probe with two RF coaxial connectors fixed on the adjacent two l×h sides. The probe metal cover 1 is made of a metal material with an electrical conductivity not less than 4.10×107 S/m. Since the microwave propagates in the waveguide when the microwave is transmitted in the waveguide, there is a current on the inner wall surface of the waveguide, which has nothing to do with the material of the waveguide itself. , Gold or silver can be plated on the inner wall of the probe metal cover 1, which reduces the loss during microwave transmission. The shape of the gold-plated or silver metal cover on the inner wall is a rectangular parallelepiped metal box with equal bases and no bottom. The metal cover has a length of l, a width of l, and a height of h (0<h≤l). Two identical RF coaxial connectors are respectively fixed at the center of the two adjacent l×h side surfaces of the metal cover 1 , namely a first RF coaxial connector T and a second RF coaxial connector D. These two radio frequency coaxial connectors are female-to-male connectors, their male ends are inside the probe metal cover 1 , and their female ends are outside the probe metal cover 1 .
搭建实验系统，如图9所示，本发明设计的微波检测探头应用的实验系统由微波矢量网络分析仪4、第一同轴线电缆2、第二同轴线电缆3、微波检测探头和探头支架组成。微波矢量网络分析仪4和第一同轴线电缆2一端连接，第一同轴线电缆2另一端与金属罩1上的第一射频同轴连接器T连接，同时，微波矢量网络分析仪4和第二同轴线电缆3一端连接，第二同轴线电缆3另一端与金属罩1上的第一射频同轴连接器D连接。金属板件的长L、宽W、高H。微波检测探头固定在探头支架上，探头支架可以在x、y、z三个方向移动。检测金属板件时，如图10所示，移动探头支架到(X,Y),待检测区域为[X‐l/2,X+l/2]×[Y‐l/2,Y+l/2]。在z方向上移动探头支架，将微波检测探头紧贴在金属板件表面，这样金属罩和待测金属板件构成矩形波导管。Build experimental system, as shown in Figure 9, the experimental system that the microwave detection probe application of the present invention design is by microwave vector network analyzer 4, the first coaxial cable 2, the second coaxial cable 3, microwave detection probe and probe holder composition. The microwave vector network analyzer 4 is connected to one end of the first coaxial cable 2, and the other end of the first coaxial cable 2 is connected to the first radio frequency coaxial connector T on the metal cover 1. At the same time, the microwave vector network analyzer 4 and the first One end of the two coaxial cables 3 is connected, and the other end of the second coaxial cable 3 is connected to the first RF coaxial connector D on the metal cover 1 . The length L, width W, and height H of the metal plate. The microwave detection probe is fixed on the probe bracket, and the probe bracket can move in three directions of x, y, and z. When detecting metal plates, as shown in Figure 10, move the probe bracket to (X, Y), and the area to be detected is [X‐l/2, X+l/2]×[Y‐l/2, Y+l /2]. Move the probe holder in the z direction, and attach the microwave detection probe to the surface of the metal plate, so that the metal cover and the metal plate to be tested form a rectangular waveguide.
微波矢量网络分析仪通过同轴电缆和射频同轴连接器(T或者D)分别给微波检测探头中提供微波信号，使微波在探头中沿特定方向传播：当微波矢量网络分析仪通过同轴电缆和第一射频同轴连接器T给微波检测探头提供微波信号时，微波在探头中沿着x方向传播；当微波矢量网络分析仪通过同轴电缆和第二射频同轴连接器D给微波检测探头提供微波信号时，微波在探头中沿着y方向传播。第一射频同轴连接器T和第二射频同轴连接器D的公头在探头内部，使探头内微波的传播更集中。同时，微波矢量网络分析仪通过同轴线电缆和微波检测探头上的同一射频同轴连接器检测反射波信号。当金属板件存在缺陷时，阻碍波导管内壁表面电流的流动。波导管内壁表面电流的变化引起波导腔中传输的微波的变化，微波矢量网络分析仪在射频同轴连接器中检测到的反射波信号携有与缺陷位置有关的信息。通过反傅立叶变换，计算得出时域信号。观察时域信号在矩形波导管终端产生的反射峰Tend时刻前是否存在的显著波峰。若存在这样的显著波峰，通过这个显著波峰时刻确定缺陷的位置。The microwave vector network analyzer provides microwave signals to the microwave detection probe through the coaxial cable and the RF coaxial connector (T or D), so that the microwave propagates in a specific direction in the probe: when the microwave vector network analyzer passes the coaxial cable When the microwave signal is provided to the microwave detection probe with the first radio frequency coaxial connector T, the microwave propagates along the x direction in the probe; when the microwave vector network analyzer passes the coaxial cable and the second radio frequency coaxial connector D to the microwave detection When the probe provides a microwave signal, the microwave propagates along the y direction in the probe. The male ends of the first radio frequency coaxial connector T and the second radio frequency coaxial connector D are inside the probe, so that the propagation of microwaves in the probe is more concentrated. At the same time, the microwave vector network analyzer detects the reflected wave signal through the coaxial cable and the same RF coaxial connector on the microwave detection probe. When there is a defect in the metal plate, it hinders the flow of current on the inner wall surface of the waveguide. The change of the surface current on the inner wall of the waveguide causes the change of the microwave transmitted in the waveguide cavity, and the reflected wave signal detected by the microwave vector network analyzer in the RF coaxial connector carries information related to the location of the defect. Through the inverse Fourier transform, the time domain signal is calculated. Observe whether there is a significant peak in the time domain signal before the reflection peak Tend generated by the terminal of the rectangular waveguide. If there is such a significant peak, determine the position of the defect through this significant peak time.
针对检测的裂纹方向选择相应的主导模式微波，TE波主导模式微波检测平行于微波传输方向的缺陷灵敏度高；TM波主导模式微波检测垂直于微波传输方向的缺陷灵敏度高。根据微波检测探头的尺寸和主导模式微波、检测灵敏度(与缺陷尺寸的数量级有关)确定检测波的频率范围。根据公式确定微波的截止频率，其中c是真空中的光速，a,b是矩形波导的长边和短边，m,n是不全为零的自然数。The corresponding dominant mode microwave is selected for the detected crack direction. The TE wave dominant mode microwave detects defects parallel to the microwave transmission direction with high sensitivity; the TM wave dominant mode microwave detects defects perpendicular to the microwave transmission direction with high sensitivity. The frequency range of the detection wave is determined according to the size of the microwave detection probe, the dominant mode microwave, and the detection sensitivity (related to the order of magnitude of the defect size). According to the formula Determine the cut-off frequency of the microwave, where c is the speed of light in vacuum, a, b are the long and short sides of the rectangular waveguide, m, n are natural numbers that are not all zero.
具体检测时，首先，微波矢量网络分析仪通过同轴线电缆和微波检测探头上的第一射频同轴连接器T给探头提供信号，使微波在探头内沿着x方向传播。同时，微波矢量网络分析仪通过同轴线电缆和微波检测探头上的第一射频同轴连接器T检测反射的微波信号。通过反傅立叶变换，计算得出时域信号。观察时域信号在矩形波导管终端产生的反射峰Tend时刻前是否存在的显著波峰。若存在这样的显著波峰，通过这个显著波峰时刻确定缺陷的相对横坐标。否则，移动探头支架到下一个检测位置，继续检测，直至完成全部待检测区域的检测。其次，微波矢量网络分析仪通过同轴线电缆和微波检测探头上的第二射频同轴连接器D给微波检测探头提供微波信号，使微波在探头中沿着y方向传播。同时，微波矢量网络分析仪通过同轴线电缆和微波检测探头上的第二射频同轴连接器D检测反射的微波信号，通过反傅立叶变换，计算得出时域信号。观察时域信号在矩形波导管终端产生的反射峰Tend时刻前的显著波峰，通过这个显著波峰时刻确定缺陷的相对纵坐标。For specific detection, first, the microwave vector network analyzer provides signals to the probe through the coaxial cable and the first radio frequency coaxial connector T on the microwave detection probe, so that the microwave propagates along the x direction in the probe. At the same time, the microwave vector network analyzer detects the reflected microwave signal through the coaxial cable and the first radio frequency coaxial connector T on the microwave detection probe. Through the inverse Fourier transform, the time domain signal is calculated. Observe whether there is a significant peak in the time domain signal before the reflection peak Tend generated by the terminal of the rectangular waveguide. If there is such a significant peak, determine the relative abscissa of the defect through this significant peak time. Otherwise, move the probe holder to the next detection position, and continue detection until the detection of all regions to be detected is completed. Secondly, the microwave vector network analyzer provides microwave signals to the microwave detection probe through the coaxial cable and the second radio frequency coaxial connector D on the microwave detection probe, so that the microwave propagates along the y direction in the probe. At the same time, the microwave vector network analyzer detects the reflected microwave signal through the coaxial cable and the second radio frequency coaxial connector D on the microwave detection probe, and calculates the time domain signal through inverse Fourier transform. Observe the significant peak of the time-domain signal before the reflection peak Tend time generated by the terminal of the rectangular waveguide, and determine the relative ordinate of the defect through this significant peak time.
1)如图1‐8，设计制作微波检测探头，主要包括高电导率探头金属罩1，以及分别固定在探头金属罩1相邻的两个l×h侧面中心上的两只射频同轴连接器，分别为第一射频同轴连接器T和第二射频同轴连接器D。1) As shown in Figure 1-8, the microwave detection probe is designed and manufactured, mainly including the metal cover 1 of the high conductivity probe, and two RF coaxial connections respectively fixed on the center of the two adjacent l×h sides of the metal cover 1 of the probe The connectors are the first radio frequency coaxial connector T and the second radio frequency coaxial connector D respectively.
2)在金属板件上制作多处缺陷。2) Make multiple defects on the sheet metal.
3)实验系统主要由微波矢量网络分析仪，同轴线电缆，微波检测探头，和探头支架组成。搭建实验系统，如图9，微波矢量网络分析仪4第一同轴线电缆2一端连接，第一同轴线电缆2另一端与金属罩1上的第一射频同轴连接器T连接，同时，微波矢量网络分析仪4和第二同轴线电缆3一端连接，第二同轴线电缆3另一端与金属罩1上的第一射频同轴连接器D连接。微波检测探头固定在探头支架上，探头支架可以在x、y、z三个方向上移动。3) The experimental system is mainly composed of microwave vector network analyzer, coaxial cable, microwave detection probe, and probe bracket. Build the experimental system, as shown in Figure 9, one end of the first coaxial cable 2 of the microwave vector network analyzer 4 is connected, and the other end of the first coaxial cable 2 is connected with the first radio frequency coaxial connector T on the metal cover 1, and at the same time, the microwave The vector network analyzer 4 is connected to one end of the second coaxial cable 3 , and the other end of the second coaxial cable 3 is connected to the first radio frequency coaxial connector D on the metal cover 1 . The microwave detection probe is fixed on the probe bracket, and the probe bracket can move in three directions of x, y, and z.
4)为了消除仪器对测量结果的影响，测量前需要对仪器进行电校准，保证微波检测探头上的两只射频同轴连接器公头为零基准面。4) In order to eliminate the influence of the instrument on the measurement results, the instrument needs to be electrically calibrated before measurement to ensure that the two RF coaxial connector males on the microwave detection probe are at the zero reference plane.
5)在标准金属板件上，对微波检测探头进行群速度校准。5) Carry out group velocity calibration on the microwave detection probe on the standard metal plate.
6)在待检测金属板件区域移动探头支架，检测缺陷，确定缺陷位置。6) Move the probe holder in the area of the metal plate to be tested to detect defects and determine the location of the defect.
检测缺陷和缺陷定位的具体步骤如下：The specific steps of defect detection and defect location are as follows:
1)移动探头支架到位置(X,Y)，检测区域为[X‐l/2,X+l/2]×[Y‐l/2,Y+l/2]。在z方向上移动探头支架，将微波检测探头紧贴在金属板件表面。1) Move the probe holder to the position (X, Y), and the detection area is [X‐l/2, X+l/2]×[Y‐l/2, Y+l/2]. Move the probe holder in the z direction, and attach the microwave detection probe to the surface of the metal plate.
2)微波矢量网络分析仪通过同轴线电缆和微波检测探头上的第一射频同轴连接器T给微波检测探头提供信号，使微波在探头中沿着x方向传播。微波矢量网络分析仪在第一射频同轴连接器T中检测反射的微波信号。2) The microwave vector network analyzer provides signals to the microwave detection probe through the coaxial cable and the first radio frequency coaxial connector T on the microwave detection probe, so that the microwave propagates along the x direction in the probe. The microwave vector network analyzer detects the reflected microwave signal in the first radio frequency coaxial connector T.
3)通过反傅立叶变换，计算得出时域信号。若时域信号在矩形波导管终端产生的反射峰Tend时刻前不存在明显的反射波峰，移动探头到下一个检测位置，重复步骤1)‐3)，继续金属板件表面缺陷的检测，直至完成全部待检测区域的检测。若在矩形波导管终端反射峰Tend时刻前存在明显的反射波峰，采用校准后的群速度确定缺陷的相对横坐标xr。3) Calculate the time-domain signal through inverse Fourier transform. If the time-domain signal does not have an obvious reflection peak before the reflection peak Tend time generated by the terminal of the rectangular waveguide, move the probe to the next detection position, repeat steps 1)-3), and continue to detect surface defects on the metal plate until Complete the detection of all areas to be detected. If there is an obvious reflection peak before the moment Tend of the terminal reflection peak of the rectangular waveguide, use the calibrated group velocity to determine the relative abscissa xr of the defect.
4)微波矢量网络分析仪通过同轴线电缆和微波检测探头上的第二射频同轴连接器D向微波检测探头提供微波信号，使微波在探头中沿着y方向传播。微波矢量网络分析仪在第二射频同轴连接器D中检测反射的微波信号。4) The microwave vector network analyzer provides microwave signals to the microwave detection probe through the coaxial cable and the second radio frequency coaxial connector D on the microwave detection probe, so that the microwave propagates along the y direction in the probe. The microwave vector network analyzer detects the reflected microwave signal in the second radio frequency coaxial connector D.
5)通过反傅立叶变换，计算得出时域信号。观察时域信号在矩形波导管终端产生的反射峰Tend时刻前的显著波峰，通过这个显著波峰时刻确定缺陷的相对纵坐标yr。5) Calculate the time-domain signal through inverse Fourier transform. Observe the significant peak of the time-domain signal before the reflection peak Tend time generated by the terminal of the rectangular waveguide, and determine the relative ordinate yr of the defect through this significant peak time.
6)采用公式x＝X+xr‐l/2,y＝Y+yr‐l/2计算，最终确定缺陷在被测金属板面上位置。6) Use the formula x=X+xr -l/2, y=Y+yr -l/2 to calculate, and finally determine the position of the defect on the surface of the metal plate to be tested.
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| CN201710079641.4ACN106908456B (en) | 2017-02-14 | 2017-02-14 | A kind of metal sheet surface defects detection and the microwave detection probe and method of positioning |
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