Industrial Sensors and Actuators

Pamela C Fitzgerald

Bruce W Maxfield

Magnetic flux leakage inspection apparatus systems with independently suspended magnetic sensor blocks. The apparatus includes a magnet and a sensor assembly. The magnet is disposed over a surface of a magnetizable material under inspection for inducing magnetic flux in the material, and the sensor assembly is disposed in a predetermined inspection position over the surface for detecting magnetic flux leakage from the material that may indicate a magnetic anomaly in the material. The magnet and sensor assembly are moved along over the surface while the sensor assembly scans for magnetic leakage flux. The sensor assembly is formed with one or more independently suspended sensor blocks, each block including a plurality of sensors rigidly held in the block for detecting magnetic flux leakage. Each sensor block is independently mounted to permit the block to move perpendicular to the surface under inspection during the course of measurement as the sensor assembly and the surface are moved in scanning relation to one another. To avoid contamination of the measurement results by the normally present parallel flux leakage components, each block is subject to stringent constraints on the permitted departures of the perpendicular movement from perpendicularity, that is, on the amount by which the block may tilt as it undergoes its perpendicular movement. Each of the one or more blocks may be disposed to ride on the surface of the material under inspection, and each block may then undergo perpendicular movement independent of any other block in response to variations of the surface encountered in the course of inspection without causing undesirable magnetic field measurements to be mixed into the detected signal that would otherwise mask the much weaker desired signal indicative of magnetic anomalies.

Magnetic flux leakage inspection apparatus with surface-responsive

Tank bottom inspection apparatus of the magnetic flux leakage type having a powered release mechanism for reducing the magnetic attraction of the apparatus to the tank bottom. The apparatus is wheeled over the tank bottom surface and includes a magnet assembly disposed over the surface for inducing magnetic flux in the material under inspection and a sensor assembly for detecting magnetic flux leakage from the material indicative of magnetic anomalies. A powered actuator permits the operator to retract the magnet assembly away from the surface, reducing the magnetic attraction to the surface and thereby reducing magnetic resistance to movement of the apparatus over the surface. The operator retracts the magnet assembly for maneuvering the apparatus over and around obstacles on the surface with greatly reduced magnetic attraction to the surface. The operator is then able to return the magnet assembly to a precise inspection position for continued inspection of the surface. In one embodiment an actuator is coupled to the magnet assembly so as to move the magnet assembly relative to the apparatus wheels, which remain in contact with the surface. In another embodiment the actuator may be extended to raise the front of the apparatus, including the front wheels, off the surface so as to displace the magnet assembly away from the surface, thereby providing enhanced maneuverability for avoiding obstacles and for positioning the apparatus for inspection of the surface.

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Berkeley, CA, United States of America

Pamela C Fitzgerald