Electromagnetic ultrasonic transducer for measuring wall thickness of test piece and method for measuring wall thickness of test piece

Abstract

The invention discloses an electromagnetic ultrasonic transducer for measuring wall thickness of a test piece and a method for measuring the wall thickness of the test piece. The transducer comprises an upper shell, a lower shell which is abutted with the upper shell and comprises a secondary stepped hole at the bottom, an exciting plane coil which is arranged inside the deepest stepped hole at the bottom of the lower shell, a receiving plane coil which is arranged inside the deeper stepped hole at the bottom of the lower shell and coaxially laminated with the exciting plane coil, a shielding layer and a magnet element, which are sequentially arranged on the receiving plane coil, and a joint, which is arranged on the upper shell, respectively connected with the two plane coils through an insulated wire and used for being connected with a thickness meter so as to measure the wall thickness of the test piece. The two plane coils do not interfere with each other in a space so that the transducer has high exciting efficiency, high receiving sensitivity and high signal-to-noise ratio, and simultaneously, reduces a measuring blind zone by arrangement of the designed dual coils and other elements.

Description

technical field [0001] The invention belongs to the field of ultrasonic nondestructive testing, and more specifically relates to an electromagnetic ultrasonic sensor and a measuring method thereof for measuring the wall thickness of test pieces such as steel pipes. Background technique [0002] With the improvement of users' quality requirements for seamless steel pipes and other products, the requirement for continuous wall thickness measurement of steel pipes in the production process is becoming more and more urgent, and a non-contact wall thickness measurement technology is needed. On the other hand, in order to ensure the reliable operation of pressure-bearing equipment, the demand for thickness measurement in service is also increasing, and a thickness measurement technology suitable for high temperature is needed. As a method to meet the above requirements, electromagnetic ultrasonic thickness measurement has been paid more and more attention in practical application....

AI Technical Summary

Problems solved by technology

Chinese patent CN99118154.9 discloses an improved main pulse signal overload correction electromagnetic acoustic transducer, which uses a separate exciting coil and receiving coil design to reduce the blind area of ​​the electromagnetic ultrasonic sensor, but the patent is to reduce the gap between the two coils. The shielding designed for the coupling of the receiving coil will impair the ability of the receiving coil to detect ultrasonic waves, and the patent does not involve the difference in the design of the excitation coil and the receiving coil

Chinese patent CN93206367.5 discloses an electromagnetic ultrasonic thickness gauge, which uses a double-wire winding method to make excitation and receiving coils with the same geometric size and number of turns, so that the distance between the two coils and the test piece is the same, but for With the same wire diameter and coil size, the number of turns of the excitation coil and receiving coil of this patent is only half of that of the single-coil sensor, which leads to a significant drop in excitation and reception efficiency

In addition, Chinese patent CN200910073194.7 also discloses an electromagnetic ultrasonic thickness gauge and its measurement method. The excitation and receiving coils of the sensor are respectively fabricated on both sides of a 0.5mm thick printed circuit board, and one side of the receiving coil is close to the test piece. The number of turns of the two coils is different but the diameter is the same, but the patent uses a pulse electromagnet without an iron core, which needs to be used with a pulse power supply, which increases the complexity of use, and its coil design is less effective when magnetized with a permanent magnet

Images