Cross pulse eddy current testing probe
Technical Field
The utility model relates to a nondestructive test device, especially a can detect alternately pulse eddy current probe of all-round crack defect.
Background
The pulsed eddy current inspection technology is a new eddy current inspection technology based on the electromagnetic induction principle and is used for detecting defects in conductive materials. The principle of pulsed eddy current detection is basically the same as that of conventional eddy current detection, with the difference in excitation mode and signal analysis method. The excitation of the general pulse eddy current detection technology adopts a rectangular pulse signal, and because the frequency spectrum of the rectangular pulse signal is rich, the detection signal contains more frequency domain information and has stronger deep defect detection capability; in addition, the pulse eddy current detection technology has the advantages of simple operation, high detection speed, simple structure, strong anti-interference capability, easy realization of miniaturization of instruments and the like.
The eddy current probe is also called as an eddy current sensor and is used for connecting a tested piece and an important component of an eddy current detection system and converting defect information in the tested piece into an electric signal to be output. The performance of the probe is directly related to the detection accuracy of the whole system. Pulsed eddy current probes should have three basic functions: firstly, good eddy current can be induced in a tested piece; and secondly, the signal reflecting the condition of the tested piece can be detected and picked up, and analyzed and evaluated. Secondly, the pulsed eddy current probe is required to have the capability of suppressing noise, for example, in defect detection, the probe inclination, lift-off, temperature, humidity, external electromagnetic interference, and the like should be suppressed.
How to effectively detect crack defects in different directions in a tested piece is always a hot spot discussed in eddy current nondestructive testing. Taking surface fatigue crack as an example, it can propagate in any direction on a 2D plane. According to the eddy current flow characteristics, when the flow direction of the eddy current in the tested piece is perpendicular to the defect direction, the interference capability is strong, and the detectability is good; when the two are parallel, the interference is weak and the detectability is poor. However, most modern major equipment operates under the conditions of high temperature, high pressure, high speed and high load, important parts of the modern major equipment are made of metal materials, if cracks exist in the parts or occur in the operation of the equipment, the operation quality of the equipment can be reduced, the safety is reduced, even malignant accidents occur, and in some major accidents, the factors of crack defects account for a great proportion. Therefore, how to design the probe so that the probe can effectively detect the crack defects in different directions is a problem to be solved urgently by the pulse eddy current detection technology.
SUMMERY OF THE UTILITY MODEL
The utility model discloses an overcome above-mentioned problem, provide a can effectively detect pulse eddy current test probe of all-round crack defect, this probe interference killing feature is strong, and sensitivity is high, and more importantly has the function of autozero, can discern the surface that probably extends to all directions and the crack defect under the surface.
The utility model adopts the technical proposal that: the utility model provides a crossing pulse eddy current inspection probe, includes two mutually perpendicular's excitation coil A and B, detection coil C and the cylindrical iron core D who opens the recess, its characterized in that: the cylindrical iron core D is provided with two axial rectangular grooves which are perpendicular to each other and a circumferential circular groove; the two excitation coils A and B are respectively wound in the two axial rectangular grooves; the detection coil C is wound in the circumferential circular groove; the detection coil C is arranged inside the two excitation coils A and B; further, the two mutually perpendicular exciting coils A and B are excited by using two non-overlapping pulses to generate two non-overlapping pulsed magnetic fields, so that two non-overlapping induced eddy currents are generated in the tested piece; the detection coil C is used for receiving an induction signal of the tested piece in the eddy current field.
The exciting coil A, B and the detecting coil C are wound in the groove of the cylindrical iron core, so that the coil does not change the size of the probe, and the miniaturization design of the probe is facilitated.
Compare in ordinary probe, the utility model has the advantages of: the two non-overlapping pulses are used as excitation to drive the exciting coils a and B respectively, i.e. when pulse excitation is performed on the exciting coil a, only the exciting coil a is active, and the probe cannot detect cracks perpendicular to the exciting coil a, but when the exciting coil B is active, cracks perpendicular to the exciting coil a can be detected, i.e. two responses are performed at different time periods of the same period, so the probe can detect cracks in all different directions.
Drawings
Fig. 1 is a three-dimensional schematic diagram of an iron core of the cross pulse eddy current inspection probe of the present invention.
Fig. 2 is a three-dimensional schematic diagram of the coil of the cross pulse eddy current testing probe of the present invention.
Detailed Description
As shown in fig. 1, the cylindrical core D is provided with two mutually perpendicular axial rectangular grooves and a circumferential circular groove.
As shown in fig. 2, the two excitation coils a and B are respectively wound in the two axial rectangular grooves; the detection coil C is wound in the circumferential circular groove; the detection coil C is inside the two excitation coils a and B.
Further, in the above embodiment, when the probe is used to detect defects, the two mutually perpendicular excitation coils a and B are excited by two non-overlapping pulses to generate two non-overlapping pulsed magnetic fields, so as to generate two non-overlapping induced eddy currents in the tested piece; the detection coil C is used for receiving an induction signal of the tested piece in the eddy current field.
In the above example, the probe of the structure has strong anti-interference capability and high sensitivity, more importantly, has the function of automatic zero setting, can identify surface and subsurface crack defects which may extend in all directions, and plays an important role in ensuring the safety of equipment.