US 7,804,295 B2 · Apparatus and method for detection of defects using flux leakage techniques

Abstract

An apparatus for the detection of defects utilizing non-destructive flux leakage techniques in ferrous materials includes rare earth magnets which are supported at an angle in the order of 45 degrees with the surface of the test specimen to induce a magnetic field within the material. The angled arrangement draws the field into the specimen over a larger surface area, reducing reluctance and ensuring that the field does not shallow within the material. The device provides real-time, three dimensional, visual feedback to the user and includes built-in means for data storage and retrieval without the need for an external computer interface. A distance sensor is used to correct the signal from the sensor array for distance from the surface. A position analyzing device utilizes the magnetic field to determine the position of the apparatus along the surface of the test material, increasing the accuracy in position measurement during testing.

Claims24

Dependent claims

An apparatus for detecting discontinuities on or below a surface of a magnetizable material comprising:

a support arranged to be located adjacent the surface;
a drive arrangement for causing relative movement of the support along the surface;
a magnetizing device carried on the support for inducing a magnetic field in and above the material;
an array of sensors carried on the support where each sensor is arranged to detect magnetic flux leakage from the material and produce an output signal corresponding thereto;
and an analyzing device to detect the presence of discontinuities in the material based on the signals from the sensors and generate data on said discontinuities therefrom;
and a lift-off distance measuring device for continuously measuring a lift-off distance between the sensor array and the material surface so as to generate lift-off distance data and wherein the analyzing device is arranged to use the lift-off distance data to calibrate the signal from the sensors to the appropriate magnitude according to the lift-off distance.

3 more elements

An apparatus for detecting discontinuities on or below a surface of a magnetizable material comprising:

a support arranged to be located adjacent the surface;
a drive arrangement for causing relative movement of the support along the surface;
a magnetizing device carried on the support for inducing a magnetic field in and above the material;
an array of sensors carried on the support where each sensor is arranged to detect magnetic flux leakage from the material and produce an output signal corresponding thereto;
an analyzing device to detect the presence of discontinuities in the material based on the signals from the sensors and generate data on said discontinuities therefrom;
and a mechanical encoder device for tracking the position displacement as the apparatus travels along the surface of the material so that the relative position associated with a detected discontinuity can be added to the data on said discontinuity;
wherein the analyzing device includes a position analyzing device which utilizes the magnetic field to determine the position of the apparatus along the surface of the test material for determining a relative position of the apparatus along the surface of the material wherein the position information obtained by this position analyzing device is compared with the position information obtained by the mechanical encoder device for higher accuracy in position measurement.

4 more elements

Dependencies are inferred from the claim text.

Apparatus and method for detection of defects using flux leakage techniques

Life of this patent

Apparatus and method for detection of defects using flux leakage techniques

Life of this patent

Abstract

Claims24