Eddy current testing is an important application of the eddy current effect. When the detection coil carrying alternating current is close to the conductive test piece, the test piece will induce eddy currents due to the action of the coil magnetic field.
The size, phase and fluidity of the eddy current of the eddy current flaw detector are affected by the conductivity of the test piece and the reaction of the eddy current will change the impedance of the detection coil.
Therefore, by measuring the change in the impedance of the detection coil (or the change in the induced voltage on the coil), it is possible to conclude whether the material being inspected is defective or not.
Eddy current flaw detection equipment is a new generation of eddy current equipment produced by eddy current equipment manufacturers used for metal online and offline flaw detection. Eddy current flaw detector adopts advanced digital electronic technology and microcomputer technology, which is simple and convenient to operate. It provides users with a reliable and stable operating platform with highly sensitive performance and reliable indicators.
Eddy current flaw detection equipment measures the amplitude and phase of the impedance change, which means it can indirectly measure the abnormality or defect of the workpiece surface and near-surface materials. Changes in electromagnetic effects due to differences in these variables produce electrical signals. When the signal is amplified and converted, it drives the alarm or display device, performs alarm and sorting, and finally detects defective products.
Eddy current flaw detector is mainly composed of positioning device, eddy current probe, lifting device, multi-channel intelligent eddy current flaw detector, marking system, signal converter and transmission line.
1. Positioning device: It consists of a base platform, a centering mechanism, a sensor, etc. When the steel pipe enters the magnetic saturation flaw detection, it must be stable and concentric with the probe. The centering device will ensure that the steel pipe enters the probe stably.
2. Eddy current probe: The eddy current flaw detector adopts a professionally designed high-precision eddy current probe with high precision and good anti-noise performance.
3. Lifting device: It consists of base, upper platform, lifting mechanism, etc. When the center height changes due to different diameters of flaw detection pipes, the probe should be adjusted to raise and lower to ensure that the probe and the steel pipe are always on the same level, so that the distance between the steel pipe and the probe is uniform.
4. Multi-channel intelligent eddy current flaw detector: Detect the steel pipe and find surface or near-surface defects such as the internal and external penetrating wounds, external folding, inclusions, pits and so on. Then give corresponding detection signals.
5. Marking system: It consists of marking device, base platform, cylinder, solenoid valve and controller. When an injury is detected, the marking system will mark the injured area.
Eddy current flaw detector equipment has a fast flaw detection speed. It has high detection sensitivity for lateral defects and hole-like defects. It has a certain ability to detect pits and warps on the inner and outer surfaces. Eddy current flaw detection equipment is suitable for surface and near-surface inspection of ordinary carbon tubes, stainless steel tubes, copper tubes, aluminum tubes, titanium tubes and other welded pipes. It can replace hydrostatic testing.