Pamela M Fitzgerald

US Patent:

55149561, May 7, 1996

Filed:

Oct 11, 1994

Appl. No.:

8/320326

Inventors:

Bruce W. Maxfield - Oakland CA
Pamela C. Fitzgerald - Berkeley CA

Assignee:

Industrial Sensors and Actuators - San Leandro CA

International Classification:

G01N 2783

US Classification:

324262

Abstract:

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.

US Patent:

56148259, Mar 25, 1997

Filed:

Nov 28, 1994

Appl. No.:

8/345901

Inventors:

Bruce W. Maxfield - Oakland CA
Pamela C. Fitzgerald - Berkeley CA

Assignee:

Industrial Sensors and Actuators - San Leandro CA

International Classification:

G01R 3312
G01N 2772

US Classification:

324242

Abstract:

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.