The Key Technologies Study On Automatic Ultrasonic Non-destructive Inspection Of Steel Cord Belt Surface Morphology

Belt rip is the main failure of the steel cord belt, which leads to significant economic loss. However, the current detection techniques of belt rip cannot prevent it efficiently. Developing a new detection technique to prevent and judge belt rip accurately is still a challenge. A new nondestructive testing method using ultrasonic automation technology is proposed in this thesis, and the results are summarized as follows:1. The principle and the advantages of the new detection system are analyzed. The parameters and the types of the ultrasonic transducer are chosen and the number of the transducers required is calculated based on the system requirements. The methods of choosing pseudo-random sequence parameters, modulating carrier signal and demodulating echo signal are analyzed.2. Hardware:the power and amplitude amplifier circuit of driven signal are designed. To improve the efficiency of energy transformation and the Signal to Noise Ratio of echo, an impedance matching of ultrasonic transducer and an echo receiving circuit with high precision and high gain are designed. An echo signal acquisition system is designed for further digital signal processing. Software:the modulation of carrier signal and pseudo-random signal, the design of timer/counter and the logic control of MAX1312are realized. The communicating circuit of upper computer and the sampling buffer are designed.3. The filter parameters are calculated in MATLAB. The traditional DA algorithm is improved so that it can be satisfied the high-precision high-speed digital filter. A FPGA-based low-pass digital filter is designed using VHDL language, and is validated through the simulated results.4. A echo capture system with high precision is designed to inhibit the ultrasonic crosstalk. The cross-correlation algorithm is transformed to XOR and the number of multipliers being used is reduced, so that the FPGA logic resources is reduced and the efficiency is increased. The calculated amount of the echo capture algorithm is analysed and the simulated results validate the system.