BORESONIC INSPECTION SYSTEM

摘要

53,451 An immersion based ultrasonic inspection system is disclosed which is used to interrogate the bore and near bore material of turbine and generator rotors by passing ultrasonic search units through the rotor bore. This system utilizes variable focus array inspection transducers in a shear mode inspection of the near bore material. A ranging transducer is provided which is used to correct the surface time of the inspection beam. A mapping transducer and blind bore sensor allow diameter mapping of the rotor bore as well as a blind rotor end sensing as the scan head carrying the transducers enters the bore. A scan head centering device or chuck deploys four radial arms to center and support the scan head. Each arm has roller attached to the end which contacts the bore and rolls along so that the bore will not be damaged as the scan head passes through the bore. The chuck is driven by an electric motor and coupled to a resolver allowing the chuck to be adjusted according to bore geometry mapped by the mapping transducer. The chuck includes a pneumatic disengagement device for fail-safe disengagement of the centering arms to allow retrieval of the scan head in the event of motor or wiring failure. The chuck also includes cable pathways for control cables for the various scan head motion axes. An inspection transducer carriage is provided that provides three axes of motion to the inspection transducer. A radial motion is provided by two radial support assemblies driven by an electric motor and coupled to a resolver allowing radial position to be accurately determined. An axial tilting motion is provided by engaging one radial motion assembly and holding the other at a counter position. The transducer can also be tilted circumferentially by a transducer rotation mechanism including an electric motor and a resolver. The scan head is positioned linearly and rotationally by a square hollow drive rod that allows free passage of control cables to the scan head. A drive rod seal is provided between a rotor bore immersion fluid and an axial and circumferential drive box and prevents immersion fluid from entering the drive box and same. The drive box provides both circumferential and axial motions to the scan head during an inspection through the drive rod. Position resolvers engage the moving drive rod to provide accurate positioning information for the scan head. The drive box provides rapid alternating 360.degree. plus rotations of the scan head coupled with precise steps along the axis of the rotor. The control system for the plural motion axes allows accurate positioning and positioning feedback to computers which calculate the position of flaws or material discontinuities.