Distance, probe K value and leading edge calibration (1) Select QKS-958 digital flaw detector with / manual calibration 0 function and direct reading. (2) At present, many types of digital flaw detectors cannot realize automatic calibration of small angle longitudinal wave oblique probe distance and K value. Therefore, this method uses CSK-IIIA test block to correct distance, probe K value and leading edge test by double hole method. Block and test. According to the empirical formula, the pre-sound path a is 105 periods a=n(S1+<2)-(S2+<2)n-1 where n=h2h1S1=S1+aS2=S2+aS1, S2 ultrasonic incident point to two The three probes selected before the sound path detection of the hole are used for distance, K value and leading edge calibration. When the probe moves, multiple thread reflection echoes move regularly left and right on the sound path coordinates, multiple times. The amplitude of the wave changes regularly. It is the reflection state when the same probe is used to detect the defective bolt, and the defect property is radial crack. The height of the crack itself was measured by the endpoint diffraction method to be 4.4 mm. The probe was moved along the diameter of the bolt and rotated in the positive and negative directions at the same time. The crack length (arc length) was measured by the end point 6 dB method to be 40 mm. H = 67.5mm. Detecting Depth Contrast Test Before the test, the comparative sample was made according to the specifications of the bolt. The diameter of the sample was <46mm, the length was 200mm, and the thread depth was 1.5mm. The depth was 0.2, 0.5, 1.0 and 1.5mm at 140mm, and the arc length was 10mm. . When the test detects a 0.2mm deep crack, the crack reflection echo is indistinguishable from the thread reflection echo; when detecting a 0.5mm deep crack, the crack reflection echo and the thread reflection echo can be distinguished, but not obvious. When detecting a 1mm deep crack, the crack reflection echo can be clearly distinguished from the thread reflection echo. When detecting a 1.5mm deep crack, the crack reflection echo is more distinct from the bolt reflection echo. This shows that the minimum crack depth found by this method is close to the thread depth. Due to the influence of the performance of the flaw detector and the frequency of the probe, the sensitivity of measuring the height of the crack itself by the endpoint diffraction method is only 1 mm. Mastering the method of correcting the distance, K value and measuring the front edge of the small-angle longitudinal wave oblique probe by the double hole method, in the shaft type workpiece It is very convenient to detect the radial defects on the outer surface of the end face. The key to detection is to select the appropriate longitudinal wave refraction angle BL according to the length of the shaft workpiece and the diameter of the end surface. Welded Mesh,Welded Mesh Wire,Welded Wire Mesh Panel Yongwei Metal Product Co., Ltd , http://www.hswire-mesh.com