EDDY CURRENT PROBE FOR NON-DESTRUCTIVE TESTING WITHIN HOLES IN WORKPIECES OR WITHIN PIPES

摘要

An eddy current sensor for monitoring the metallization of apertures and narrow-gauge pipes comprises an axisymmetric body (1) elongated along the axis of symmetry, on the inner surface of which is mounted a coil in the form of a helical winding wound along the axis. The body (1) is hollow, the ratio of the outer cross section D to the inner cross section d being such that 1.4 D/d 1.6; this, together with the fact that the coil (3) is mounted on the inner surface of the body (1), gives the coil greater mechanical strength and helps to protect it from damage without increasing the cross-sectional dimensions of the sensor. The internal space of the body (1) can be filled with a magnetoconductive material. It is expedient to provide inside the casing a central shaft (8) with a tapering plug at the end (7). The sensor is modified if there is a holder (6). The process for producing the sensor involves forming the coil on a dielectric elastic core (2) and producing the body (1) in its flat developed form; the casing is given its desired final shape after the core (2) with the coil (3) has been mounted on the casing when still flat.