Electromagnetic ultrasonic resonance thickness measuring method capable of adaptively regulating and controlling sweep frequency step length

The electromagnetic ultrasonic resonance thickness measurement method with adaptive frequency sweep step size has solved the problem of low efficiency in the measurement of ultra-thin workpieces by electromagnetic ultrasonic resonance thickness measurement method, and realizes fast and accurate thickness measurement, which is suitable for processing compensation and real-time measurement.

CN120970556APending Publication Date: 2025-11-18DALIAN UNIV OF TECH
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Patent Information

Application Number
CN202410601392.0
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2024-05-15
Publication Date
2025-11-18

AI Technical Summary

Technical Problem

Existing electromagnetic ultrasonic resonant thickness measurement methods are inefficient when measuring ultra-thin workpieces, cannot achieve rapid measurement, and current technologies have not effectively improved the real-time performance of thickness measurement.

Method used

An adaptive frequency sweep step size adjustment method is adopted. By shortening the frequency sweep step size near the resonant frequency and increasing the step size in other frequency bands, combined with Fourier transform and amplitude identification, frequency domain segmentation is achieved, reducing the number of frequency sweep steps and improving measurement efficiency.

Benefits of technology

By using a variable step size sweep frequency method, the number of sampling points is reduced, the thickness measurement efficiency is improved, and real-time measurement of ultra-thin wall thickness and processing measurement are integrated, thereby improving the uniformity of workpiece wall thickness.

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Abstract

The invention discloses an electromagnetic ultrasonic resonance thickness measuring method capable of adaptively regulating and controlling sweep frequency step length, which comprises the following steps of: exciting a continuous sweep frequency signal of a certain frequency band by an electromagnetic ultrasonic probe at a variable frequency step length, forming ultrasonic waves on the surface of a workpiece, penetrating the workpiece, and reflecting on the other surface of the workpiece to measure the thickness of the workpiece. The electromagnetic ultrasonic probe receives the reflected time domain signal, time-frequency conversion is conducted on the time domain signal based on the Fourier transform principle, a spectrogram is obtained, and wall thickness information of the current measuring point is calculated according to the frequency difference. However, due to the fact that the processes of frequency sweeping excitation, ultrasonic wave receiving and data processing of a series of waveforms are slow, the real-time performance of measurement can be affected, according to the electromagnetic ultrasonic resonance thickness measurement method oriented to ultrathin wall thickness measurement, frequency domain segmentation is achieved based on signal amplitude recognition, the frequency sweeping step length is shortened near the resonance frequency, and the measurement accuracy is improved. The step length is increased in other frequency bands, full-band equal-step-length frequency sweeping is replaced by variable-step-length frequency sweeping, the frequency sweeping step number is reduced, and therefore the measurement efficiency is improved.
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