Research On Key Technologies Of Multi-channel Automatic Ultrasonic Measurement And Control System For Large Parts

In industrial production,large parts are the key component of advanced manufacturing equipment.They have been widely used in aerospace,vessel,metallurgy,electric power,machinery and National Defense Science and technology and other fields.Their quality affects the safety and reliability of equipment operation directly.In order to ensure the quality of large parts,it is required to detect the bubbles,cracks,inclusions and other defects.As a nondestructive detecting technology,ultrasonic measurement has the advantages of simple operation,strong penetration ability,high detection accuracy and no radiation hazard to the human body.So it is suitable for detecting the internal defects of large parts.At present,the manual hand-held ultrasonic detector is used mainly to detect large partsin domestic.However,there are some disadvantages in this detection method,such as:slow detection speed,low precision,which easily lead to detection failure and detection fault and other phenomena.Furthermore the experienceddetecting personnel are required to operate and determine the results of the test.Therefore,in order to improve the detection speed and precision of large parts,a fast and efficient multi-channel ultrasonic automatic measurement and control system for large parts is necessary to research.The key technology of multi-channel ultrasonic automatic measurement and control system for large parts is studied in this thesis.The main work is as follows:A design scheme of multi-channel ultrasonic automatic measurement and control system for large parts is proposed.This system is composed of two parts,which are multi-channel ultrasonic automatic detection system and multi-axis automatic control system.The FPGA made by Xilinx(XC3S500E)and ARM9 made by Samsung(S3C2440)are chosen as a hardware of system,this FPGA software is designed through VHDL language on the Xilinx ISE platform,and the ARM software is written by Clanguagein the Linux system.The UDP/IP protocol was used to write the system's communication software.The upper computer software of the system is designed by Lab VIEW.The functions of multi-channel ultrasonic automatic detection and automatic control of multi-axis motor for large parts are realized.The step and step trajectory of water-logging ultrasonic probe were studied in this paper.In order to reduce the movement time of ultrasonic probeand and improve detection speed,the moving step and step trajectory of the probe were optimized.A fast switching method of multi-channel ultrasonic automatic detection system and multi-axis automatic control system is proposed.Thethread control instead of process control,which leads to orderly switching of the two systems is realized,the host computer resources isreduced,and the efficiency and accuracy of ultrasonic detecting is improved.In the MATLAB platform,the three-dimensional image model of detecting defects is established,which makes the defect judgment more intuitive and accurate.The experiment platform of multi-channel ultrasonic automatic measurement and control system based on Ethernet is built,and the experiment and debugging are carried out.The experimental results show that the system can realize automatic control of the multi-channel ultrasonic probe,movement tracks are optimal,fast switching between multi-channel ultrasonic automatic detection system and multi-axis automatic control system,and A,B,C scan imaging,and three dimensional images of internal defects.It has the advantage ofhigh detection efficiency and precision,simpleroperation and good expansion.