An electromagnetic ultrasonic transducer for automatic detection of steel bar surface

Abstract

The invention provides an electromagnetic ultrasonic energy converter for automatic detection of a surface of a steel rod and belongs to the technical field of steel rod surface inspection. The electromagnetic ultrasonic energy converter comprises a detection coil, a magnetizing device and a work piece to be detected. The magnetizing device is formed by two sets of completely same coils and shells. The coils are formed by winding varnished wires and two sets of the coils are connected in series; and when the coils are electrified by direct current, namely a stable and constant magnetic field B is axially distributed in a rod material to be detected. The shell of the magnetizing device is made of a ferromagnetic material so that a magnetic field generated by the coils is limited in a magnetic circuit formed by the shell of the magnetizing device and the rod material to be detected; and therefore, the magnetization of the rod material can be realized to the greatest extent. The electromagnetic ultrasonic energy converter is mounted on a production line of the steel rod to carry out online detection on the quality of the rod material, find out the defects on the surface of the rod material in time and ensure the quality of a rod material product.

Description

technical field [0001] The invention belongs to the technical field of steel rod surface flaw detection, and in particular provides an electromagnetic ultrasonic transducer for automatic detection of steel rod surface. Background technique [0002] The hot-rolled bar is a kind of bar with a large output, and its surface condition is poor (curvature, ellipse, roughness, thick scale, and problems such as processing stress and decarburization). Flaw detection methods either cannot detect or can only detect flaws with low sensitivity. [0003] At present, the eddy current flaw detection method is usually used to detect the surface quality of steel bars at home and abroad. Although eddy current flaw detection can suppress dimensional fluctuations, conductivity changes and other factors within a certain range, it cannot suppress the eddy current response caused by the workpiece's processing stress, surface state, heat treatment process, etc., which greatly reduces the flaw detect...

AI Technical Summary

Problems solved by technology

MFL method can detect surface cracks, but it has poor detection sensitivity for subsurface defects

[0004] Magnetic particle flaw detection is also unable to meet the needs of mass production automatic flaw detection inspection due to its slow detection speed and the need for human eyes to observe and judge flaws.

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