APPARATUS AND METHOD FOR MEASURING PROPERTIES OF A FERROMAGNETIC MATERIAL

摘要

An apparatus for measuring material properties of an object of ferromagnetic material, the apparatus including a probe, the probe including an electromagnet core defining two spaced-apart poles for inducing a magnetic field in the object, and a drive coil wound around the electromagnet core, and means to supply an alternating electric current to the drive coil to generate an alternating magnetic field in the electromagnet core and consequently in the object, wherein the probe also includes two sensing coils arranged in the vicinity of each of the poles, for sensing the magnetic flux density that links the core and the object, such sensing coils are significantly more sensitive to changes in material properties than are sensing coils overwound onto the drive coil.

主权项

1. An apparatus for measuring material properties of an object of ferromagnetic material, the apparatus comprising:
a probe comprising:
an electromagnet core defining two spaced-apart poles for inducing a magnetic field in the object, so faces of the two spaced-apart poles define four corners of the probe;a drive coil wound around the electromagnet core; andat least four sensing coils configured to sense the magnetic flux density that links the electromagnet core and the object, wherein at least two of the at least four sensing coils are arranged in the vicinity of each of the two spaced-apart poles; and an alternating current supply configured to supply an alternating electric current to the drive coil to generate an alternating magnetic field in the electromagnet core and consequently in the object, wherein two of the at least four sensing coils are arranged on the face of each pole, each of the two sensing coils is between the face of the respective pole and a surface of the object, and each of the two sensing coils are attached at opposite ends of the face of the respective pole so that one sensing coil is near each of the four corners of the probe.