Annular eddy current test coil with magnetic laminations adjacent a limited circumferential extent

• US 4,002,967 A
• Filed: 08/01/1975
• Issued: 01/11/1977
• Est. Priority Date: 08/01/1975
• Status: Expired due to Term

• Current Assignee: Aluminum Company of America (Howmet Aerospace, Inc.)
• Original Assignee: Aluminum Company of America (Howmet Aerospace, Inc.)
• Inventors: Fennell, S. Reed
• Primary Examiner(s): Corcoran, Robert J.
• Application Number:
  US05/601,203
• Time in Patent Office: 529 Days
• Field of Search: 324/37, 324/40, 324/34 R, 336/233, 336/234
• US Class Current: 324/238
• CPC Class Codes: G01N 27/9006 Details, e.g. in the structure or functioning of sensors
• CPC Class Codes: H01F 17/04 with magnetic core
• CPC Class Codes: H01F 2017/0053 with means to reduce eddy currents

Abstract

A magnetic pole and coil assembly for concentrating eddy currents in a limited peripheral portion of a metal product being examined by the assembly. The assembly comprises at least one winding adapted to produce a magnetic field when supplied with alternating electrical current, and laminations of high permeability magnetic material disposed closely adjacent a portion of the winding to concentrate the magnetic field in the vicinity of the magnetic laminations.

Claims

1. A magnetic pole and coil assembly for limiting and concentrating eddy currents in a peripheral arc portion of a metal product, the assembly comprising

at least one annular winding electrically connectable to a source of alternating or pulsating electrical energy, and adapted to produce magnetic flux capable of inducing eddy currents in a metal product when the winding is energized by said source, said winding being adapted to have the product pass therethrough and

laminations of a magnetic material disposed adjacent a limited circumferential portion of said winding for concentrating and limiting the magnetic flux produced by said winding in and to the area of the magnetic laminations, and thereby being effective to increase the density of the flux and eddy currents in a predetermined arc portion of a metal product when the metal product is directed past the laminations and through the winding in a rapid, continuous manner and in close proximity but spaced relation to the laminations and winding.

2. The assembly of claim 1 in which a structure made of non-magnetic material is located adjacent the remaining circumferential portion of the annular winding and in a position opposed to that of the magnetic laminations.

3. The assembly of claim 2 in which the magnetic laminations and the non-magnetic material have a configuration that provides an opening capable of passing therethrough metal product to be examined by the assembly.

4. The assembly of claim 2 including a second annular winding connectable to a source of electrical energy, and spaced from the winding of claim 1 by the magnetic laminations and the non-magnetic material.

5. The assembly of claim 4 including a tubular liner made of non-magnetic material extending between the windings and between the laminations and non-magnetic material, said tubular liner being adapted to receive and pass elongated product therethrough.

6. The assembly of claim 2 in which the non-magnetic structure is in the form of laminations made from a non-magnetic material.

7. The assembly of claim 6 in which the magnetic and non-magnetic laminations are held together by fastening means and at least one, common, non-magnetic lamination, said fastening means securing the laminations, including the common lamination, together.