A Design Method Using Multiple Frequency Simultaneous Excitation to Improve Magnetic Particle Flaw Detection Capability

Abstract

The invention discloses a design method for improving the magnetic powder inspection capacity through the simultaneous excitation at a plurality of frequencies. Magnet yoke coils are simultaneously excited by using excitation currents with a plurality of different frequencies based on the principle that induced magnetic fields generated by the excitation currents with the different frequencies have different magnetization deeps for an inspected workpiece, so that the inspected workpiece is comprehensively and uniformly magnetized, defective leakage magnetic fields on the surface and the inner part of the inspected workpiece are favorably escaped, magnetic powder is easy to gather, and therefore, the defect checkout capacity of the magnetic powder is greatly improved.

Description

Technical field [0001] The invention relates to a design method of a non-destructive testing device, in particular to a design method for improving the capability of magnetic powder flaw detection by simultaneously exciting multiple frequencies. Background technique [0002] Magnetic particle testing is a common non-destructive testing method for material defect detection of ferromagnetic workpieces. During the testing process, the workpiece to be inspected needs to be magnetized first, and then the magnetic powder is evenly spread on the inspection surface of the inspected workpiece for inspection. During the detection process, the magnetization effect of the inspected workpiece directly affects the accuracy and detection effect of the magnetic particle inspection. The more uniform the magnetization of the inspected workpiece, the better the detection accuracy and detection effect. Commonly used magnetization methods include DC magnetization and AC magnetization methods. Th...

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Problems solved by technology

However, the single-frequency magnetization current has a certain magnetization depth. For some large-scale inspected workpieces, it is difficult to obtain a comprehensive and uniform magnetization of the inspected workpiece, which affects the magnetic particle inspection effect.

In recent years, there is a method of changing the frequency of the magnetizing current using frequency conversion technology, see the invention patent CN201110355108.9, but this method can only stimulate a magnetizing current of one frequency at a time, and cannot take into account all depths, nor can it realize the comprehensive inspection of the workpiece. uniform magnetization