Research Of The Wheel Rim Flaw Detection System Based On Ultrasonic Phased Array

China High-speed Railway is developing rapidly.At present,the standard speed of the “Fuxing” EMU has reached 350km/h.High-speed trains require very strict safety protection and detection measures,especially the part between the locomotive and the rails—the wheels.The NDT of flaws in the online detection of train wheels usually adopts a combination of ultrasonic testing(UT)and magnetic particle testing(MT).And the detection of internal flaws is mainly based on UT.Traditional piezoelectric ultrasonic testing is sensitive to defects perpendicular to the beam direction because of its characteristics.However,due to a variety of reasons,the train has a lot of randomness in the operation process,so there are a lot of limitations in traditional ultrasonic testing.In recent years,with the rapid development of electronic technology,phased array ultrasonic testing(PAUT)technology has become a research hotspot.Through the orderly excitation of each array element to realize the deflection and focusing of the sound beam,the combined fan-shaped scanning,electronic scanning(linear scanning),dynamic depth focusing(DDF),etc.have more ways of working with the direction of the sound beam.This results in faster detection speed and higher sensitivity compared to traditional ultrasound.This paper aimed at the application of PAUT technology in the detection of high-speed wheel rims.It is based on the Multi 2000 phased-array card of M2 M,through the study of PAUT electronic scanning control,phased array sound field modeling and simulation,and array adaptive focus,phased array image display and reconstruction and other key technologies,set up a complete set of PAUT system for automatic detection of high-speed railway wheel rims.In this paper,the basic principle of PAUT technology was introduced in three aspects: the transmission and reception of PAUT,the focusing rule and the scanning mode.Then the research process of PAUT system for wheel rim defects was described from the aspects of PAUT transducer array,simulation analysis of emitted sound field,system hardware design,and upper computer software design.The main research work in the PAUT emission sound field simulation analysis includes: 1)establishment of a sound field model based on spatial impulse response;2)calculation of spatial impulse response of the array element;3)completion of emission based on MATLAB in Field II.The implementation of the sound field simulation program,and related simulation experiments.In the hardware and software design of the detection system,with the open characteristics of the Multi 2000,the design of the auxiliary machinery and electrical devices,and the realization of the special upper computer software program for PAUT were completed.Finally,the performance of the detection system was tested by the experiment of artificially simulated defects,and it was verified that the wheel rim detection equipment based on the system described in this paper has higher sensitivity higher reliability and more controllability sound beam than the conventional ultrasound.At the same time,aiming at the increasingly higher testing requirements of pipes and bars in metallurgical companies,the application of the PAUT system on pipe and bar was introduced and analyzed at the end of this paper.The PAUT system studied in this paper is widely used in online automatic inspection of pipe and bar in metallurgical enterprises.