Метод та засіб ультразвукового електромагнітно-акустичного контролю феромагнітних металовиробів зі складною формою перетину з невеликим розміром

Abstract

A review of the foundations for the development and deepening of methods of electromagnetic-acoustic testing of metal products is performed. The main defects of hardware, which can be revealed via be electromagnetic-acoustic method, are considered. The concepts of electromagnetic acoustic transducer are considered. The possibilities and limitations of the developed method of electromagnetic-acoustic control are described. The task of developing an electromagnetic-acoustic transducer and the associated method of a contactless ultrasonic electromagnetic-acoustic (EMA) method for exciting and receiving ultrasonic pulses is formulated. The principles of impulse control of non-dispersive torsional waves of extended tubular ferromagnetic products with a complex cross-sectional shape have been established, a new version of which would ensure an increase in the reliability of detection of defects. The theoretical issues of the formation of ultrasonic pulses of non-dispersive torsion waves by simultaneous excitation of a polarizing magnetic field and the excitation of a high-frequency electromagnetic field by a high-frequency pass coil are considered. Analysis of the parameters of the received ultrasonic pulses. The time sweeps of the implementation of the developed method of electromagnetic-acoustic conversion of ultrasonic vibrations are given. A technical description of the implementation of the developed method through an electromagnetic-acoustic transducer is given. A description of the experimental verification of the developed method of electromagnetic-acoustic conversion on a piece of a product in the form of a pipe with a cross section in the form of a rectangle with a side size of 12 mm and a wall thickness of 2 mm, made of steel st. 3, is given. The possibility of detecting defects with a ratio of the amplitudes of the reflected signal and noise of at least 20 dB at a distance of 150 mm from the EMAT to the defect has been proven.