Research On Automatic Phased Array Ultrasonic Imaging And Testing Technology For Small Diameter Bars

As an important basic raw material,the small diameter bar has been widely used in related fields such as national economy,national defense construction,and high-tech.However,due to the occurrence of various defects in the production process of bar and forging,the high temperature,high pressure and high speed working environment and the effect of alternating load will accelerate the development of defects and structural failure,which may result in Catastrophic accidents of downtime and machine crashes.Therefore,advanced non-destructive testing must be used to monitor its quality.However,among many non-destructive testing technologies,ultrasonic non-destructive testing technology has become the defect detection and quality of small diameter bars due to its strong penetrability,high resolution and detection sensitivity,rich carrying information and safety to human body.The most effective means of monitoring,and is developing towards the phased array ultrasound imaging detection based on the composite partition scanning based on the mechanical translation of the bar to be tested and the full deflection of the electron beam in the circumferential direction of the sound beam.However,for lateral defects,there are still many technical challenges in the scanning imaging using the full-coverage electronic deflection of the sound beam,and how to effectively implement the surface of the small diameter bar and the coating small diameter bar and the lateral surface defects.Phased array ultrasound imaging testing remains to be further explored.To this end,this thesis combines the National Natural Science Foundation project High-performance automated phased array ultrasonic imaging detection theory and technology of cylindrical components(NO.51675480),proposed to develop automated phased array ultrasonic imaging detection technology for small diameter bars.Research.On the basis of understanding the research status and development trend of related technologies at home and abroad,and clarifying the principle and requirements of phased array ultrasonic imaging detection for small diameter bars,the design of oblique-concave phased array ultrasonic transducers for transverse injury detection is emphasized.Optimization,synthesis and control of phased array ultrasonic beams in laminated cylindrical structures,phased array ultrasonic imaging based on mechanical and electronic composite scanning,and key techniques such as phased array ultrasonic imaging detection of small diameter bars A set of small diameter bar automatic detection system based on phased array ultrasound imaging was developed,and relevant experimental research was carried out to verify the feasibility and effectiveness of the proposed technique.Specific research work includes:In the first chapter,the important role of small diameter bar and its significance to the national econo my and social development is discussed It summarizes the research status and development trend of the bar non-destructive testing technology,and points out the automatic phased array of the small diameter bar.The advantages of online application of ultrasonic imaging detection technology clarify the research content of this paper and point out the direction for the research of subsequent chapters.In the second chapter,the theoretical and technical basis for phased array ultrasonic imaging detection of small diameter bars is established.The establishment and solution of the wave equation in the cylindrical coordinate system are completed,and the types of small diameter bar defects and the corresponding detection methods are introduced.At the same time,on the basis of clear detection targets,the design of the overall scheme of the automated phased array ultrasonic imaging detection system for small diameter bars was completed,and the functional modules were divided and the key technologies to be solved were proposed.In the third chapter,the optimization design of the oblique and concave phased array ultrasonic transducer for transverse injury detection is completed.Based on the determination of the phased array ultrasonic imaging detection method of the small diameter bar based on mechanical and electronic composite scanning,an oblique-concave phased array transducer for the detection of the transverse bar of the small diameter bar was optimized.Combined with phased array ultrasonic beam synthesis and control technology,the transducer sound field model is established,and then the influence of transducer geometry parameters on its sound field distribution is analyzed.In the fourth chapter,the research on the detection technology of the transverse flaw detection of small diameter bars based on phased array ultrasound imaging is carried out.For the lateral defects with and without the coating small diameter bar,the theoretical analysis of phased-array ultrasonic testing is carried out,and the focal point of the ultrasonic detection of the transverse-track phase-controlled array of small diameter bars is deduced.At the same time,combined with the technology of wavelet threshold denoising,the phased array ultrasonic signal is preprocessed,and the signal-to-noise ratio of the ultrasonic reflected echo signal is improved.Based on the non-uniform sampling of the echo signals,the RGB color mapping strategy is used to characterize the imaging results.In the fifth chapter,adopting distributed architecture and modular design strategy,and using multi-mode communication bus as information transmission bridge,a set of small diameter bar automated phased array ultrasonic imaging detection system based on PXI bus was developed,and the system was equipped with artificial Defective and small diameter bars and coating small diameter bars were carried out to verify the feasibility and effectiveness of the theory and technology.In the sixth chapter,the research work of this paper are reviewed and summarized,and look forward to the next research work.