The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 04, 1980
Filed:
Mar. 14, 1978
Richard M Harris, Mentor, OH (US);
Wilbert J Janos, North Ridgeville, OH (US);
Republic Steel Corporation, Cleveland, OH (US);
Abstract
An electromagnetic flaw detection system and method having automatic dynamic error balancing is disclosed. The system includes means for producing an alternating electromagnetic field and for passing a metallic workpiece to be tested along a path through the field. A differential detection coil is disposed in the field near the workpiece path. The coil responds to nonuniformities in the field caused by workpiece flaws, such as voids, to produce flaw indications. Detection circuitry actuates alarm apparatus in response to the flaw indications to further indicate need for corrective action. Automatic balancing circuitry compensates for an error signal, which the differential coil generates due to minute undesired assymmetries in the coil's mechanical structure. The balancing circuitry includes means for generating a reference signal. The reference signal is continually adjusted, in response to characteristics of the error signal, to exactly counterbalance the error signal in phase and amplitude. The coil's total output, including the error, and the adjusted reference signal, are summed at a location electrically separate from the coil to provide a flaw detection coil output in which the error is completely nulled out.