Magnetic inspection device
AssigneeNDT Technologies, Inc.
InventorHerbert R. Weischedel
Life of this patent
Estimating the term…
Abstract
A magnetic inspection device for nondestructively inspecting elongated objects, such as wire cables, pipes, and the like, for loss of metallic cross-section due to abrasion, corrosion, and external and internal discontinuities, having a magnet for inducing in sections of the object between the stations, magnetic flux at the saturation level. A magnetic flux detector having magnetic sensors positioned between the poles and laterally of the elongated object utilizes shields and flux decompressors to render the flux detector more sensitive to leakage flux caused by discontinuities in the objects.
Claims36
A magnetic inspection device for nondestructively detecting discontinuities in the form of loss in metallic cross section and localized discontinuities in elongated magnetically permeable objects, such as wire cables, rods, pipes, and the like comprising:
- a magnet having two opposite magnetic poles spaced from one another for positioning and movement relative to an elongated magnetically permeable object to be inspected with the poles at longitudinally spaced stations of the object, and for inducing in sections of the object between the stations, magnetic flux at the saturation level, the magnet also defining a ferromagnetic flux return path between the poles externally of the object for completing a flux circuit;
- a magnetic sensor assembly having a magnetic flux detector at a position between the poles and stations of the elongated object and having a sensing portion of the magnetic flux detector facing an exterior surface of the elongated object between the two magnetic poles of the magnet for sensing perturbations in leakage flux at the exterior surface caused by discontinuities in the object, as the object and inspection device move relative to one another;
- and
- a flux decompressor located between the magnetic poles of the magnet and adjacent the magnetic flux detector for reducing secondary flux at the surface of the object in the vicinity of the detector.
A magnetic inspection device for nondestructively detecting discontinuities in the form of loss in metallic cross section and localized discontinuities in elongated magnetically permeable objects, such as wire cables, rods, pipes, and the like comprising:
- a magnet having two opposite magnetic poles and for inducing, in sections of a magnetically permeable object between the poles, a magnetic flux at the saturation level;
- a magnetic sensor assembly having a magnetic flux detector positioned between the poles for sensing perturbations in leakage flux at the exterior surface of the object caused by discontinuities, as the object and inspection device move relative to one another;
- and
- a flux shield located between the magnetic sensor assembly and each magnetic pole of the magnet for absorbing secondary flux between the poles and in the vicinity of the flux detector to aid the magnetic sensor assembly in sensing the perturbations of leakage flux.
A magnetic inspection device for inspecting elongated magnetically permeable objects, such as wire cables and the like, for abrasion, corrosion, and internal discontinuities, comprising:
- a magnet having two magnetically opposite poles and a connecting ferromagnetic flux return path for movement relative to an elongated magnetically permeable object to be inspected, with the poles longitudinally separated along the object for inducing a saturated magnetic field in the portion of the object between the poles,
- whereby changes in transverse cross section and internal discontinuities of the object produce detectable changes in leakage flux from the field between the poles at the exterior surface of the object;
- a magnetic sensor assembly with a magnetic flux detector disposed between the longitudinally separated poles at one lateral side of an elongated object being inspected adjacent the exterior surface of the object with flux shields interposed between the longitudinally separated poles and the magnetic flux detector and a sensing portion of the detector exposed to the exterior surface of the object to detect the changes in leakage flux at the exterior surface as the object and magnetic inspection device move relative to one another.
A method for nondestructively inspecting an elongated magnetically permeable object, such as wire cable, pipes, and the like, for loss in metallic cross section, local discontinuities, abrasion, corrosion, internal discontinuities, and the like, comprising the steps of:
- inducing a magnetic field extending longitudinally through the elongated magnetically permeable object between longitudinally spaced stations at a saturation level, the field being part of a magnetic circuit through the object between the spaced stations, the circuit being closed externally of the object by a ferromagnetic flux return path;
- providing a magnetic sensor assembly having a magnetic flux detector to detect leakage flux from the object;
- shielding the magnetic sensor assembly between poles from secondary flux passing directly between the poles;
- moving the magnetic field and spaced stations progressively and longitudinally along the object;
- and
- sensing the changes in leakage flux at the exterior surface of the object due to the changes in metallic cross section of the object.
A method for nondestructively inspecting an elongated magnetically permeable object, such as wire cable, pipes, and the like, for loss in metallic cross section, local discontinuities, abrasion, corrosion, internal discontinuities, and the like, comprising the steps of:
- inducing magnetic flux in the elongated magnetically permeable object between longitudinally spaced stations at a saturation level;
- moving the magnetic flux and spaced stations progressively and longitudinally relative to the object;
- and
- providing a magnetic sensor assembly having a magnetic flux detector to detect leakage flux at the surface of the object as the magnetic sensor assembly and object move relative to one another;
- decompressing the flux within the object between the magnetic poles in the vicinity of the magnetic flux detector;
- sensing the changes in leakage flux at the exterior surface of the object due to the changes in metallic cross section of the object.
Dependencies are inferred from the claim text.