×

Method for detecting defects in work pieces and facility and magnetic field measuring apparatus for implementing said method

  • US 6,411,085 B1
  • Filed: 04/18/2000
  • Issued: 06/25/2002
  • Est. Priority Date: 10/20/1997
  • Status: Expired due to Term
First Claim
Patent Images

1. A method of determining a depth of a ferromagnetic impurity in a workpiece of a nonmagnetic material, comprising the steps of:

  • (a) magnetizing said ferromagnetic impurity uniformly by subjecting said workpiece at least in sections to a magnetic field;

    (b) thereafter juxtaposing said workpiece and a magnetic field measuring sensor at a first distance from a surface of said workpiece to obtain a first signal measuring magnetic field strength deriving from said ferromagnetic impurity;

    (c) then juxtaposing said workpiece and said magnetic field measuring sensor at a second distance from said surface of said workpiece different from said first distance to obtain a second signal measuring magnetic field strength deriving from said ferromagnetic impurity;

    (d) forming a signal ratio of said first and second signals as a quotient of the magnetic field strengths at said first and second distances; and

    (e) based upon said signal ratio, determining from a curve in which the dependency of the signal ratio is plotted against an impurity depth, a depth of the impurity in said workpiece from which the magnetic field strengths were measured.

View all claims
  • 4 Assignments
Timeline View
Assignment View
    ×
    ×