Method and apparatus for determining cracks in a shaft by means of an ultrasound pulse echo

摘要

Method and apparatus for detecting cracks in a shaft by means of an ultrasound pulse echo method. A test hand having an ancillary wedge is coupled to the end face of the shaft for conducting nondestructive testing of the shaft. The test head emits ultrasound pulses of a determined frequency and is moved by means of a mechanical device in front of the end face. The method makes possible reliable and reproducible detection of cracks present at the circumference of long shafts. The test head delivers sound pulses in the range of 4 to 8 MHz and is placed by means of the device at a radial distance from the shaft end face's central axis. The test head is moved in the course of the measurements in three degrees of freedom; along a radius of the shaft, along a circle of the shaft and about the axis of the test head holder. The method and apparatus are employed for testing long turbine shafts in the assembled condition from the end face on the generator side of the shaft.