DETECTION SYSTEM FOR INCIDENCE ANGLE VARIATION OF PROBE ROTATION TYPE TUBE ULTRASONIC FLAW DETECTION DEVICE

摘要

PURPOSE:To improve the accuracy of flaw detection by calculating the beam path length in a material to be inspected from variation in angle of incidence with the eccentricity of the tube to be inspected and correcting flaw detection sensitivity, etc., automatically. CONSTITUTION:An underwater distance calculating means measures the propagation time of an ultrasonic wave from the time interval between an ultrasonic wave sent signal and an echo from a probe for receiving the surface echo of the tube to be inspected and calculates the underwater distance from a probe for flaw detection to the probe for echo reception through an incidence point on the tube surface. Then, a maximum and minimum value detecting means detects the maximum and minimum values of the underwater distance in one turn of a composite probe and a maximum and minimum difference calculating means calculates the difference between the maximum and minimum values. Then, an eccentricity quantity calculating means divides the maximum-minimum difference of the underwater distance by a preset device constant to calculate the distance between the center of rotation of the composite probe and a position in the tube to be detected as an eccentric quantity in one turn. Then, an incidence angle calculating means finds the angle of incidence corresponding to the angle of rotation from the angle of rotation from a rotation angle calculating means and eccentricity quantity and calculates variation in the beam path length in the material from the angle of incidence to correct the flaw detection sensitivity automatically during the rotation of the probe, thereby making the flaw detection accurate and highly reliable.