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

DETAILED DESCRIPTION What is claimed is: 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