Report on an Eddy Current Method for Inspection of Shell Cases
Abstract
An eddy current method and the apparatus for the detection of flaws in brass cases is presented. Eddy currents are induced into the shell case by revolving the shell case about its axis of symmetry so that a portion of the shell case is always in the field of a U-shaped permanent magnet. A definite eddy pattern is interrupted by a flaw as the flaw passes through the field of the magnet. A pickup coil is placed so that it can "see" the interruption of the eddy current pattern. Suitable apparatus makes it possible to observe the flaw signal on the screen of an oscilloscope. Provision is also made to indicate the presence of the flaw by the flashing of a warning light. Oscillograms of typical flaws by the flashing of a warning light. Oscillograms of typical flaws in brass shell cases are presented. It is also pointed out that the apparatus can be used for detecting flaws in steel shell cases.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 27, 1944
- Accession Number
- AD1181851
Entities
People
- J. E. Dinger
- J. O. Grantham
Organizations
- United States Naval Research Laboratory