| 摘要 |
PURPOSE:To simply and certainly detect the crack or crack depth of the blade implanted part of the rotor disc of an electromotor, by acting tensile force in a centrifugal direction on a blade effective part and measuring the relative displacement of the tensile force and a blade/rotor. CONSTITUTION:A bridge shaped displacement meter 3 is mounted to the implanting part of a steam turbine blade 1 and a rotor 2 so as to straddle said implanting part and a strain gauge 4 is provided to said displacement meter 3. Tensile force is acted on the blade 1 in the centrifugal direction thereof by a hydraulic servo apparatus 7 constituted so as to grasp the shroud 5 of the blade top part by a jig 6 and the relation of the relative displacement of the tensile force and a blade/rotor is calculated. When there is a crack at this time, said relative displacement becomes large. Relative displacement preliminarily calculated when there is no crack is compared with the measured relative displacement to detect the presence of the crack and the depth thereof. Therefore, the crack can be detected in such a state that the blade is implanted as it is and workability can be enhanced.
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