数字化超声波探伤仪的设计与实现

摘    要 
 
 超声检测是无损检测的主要技术之一，已被广泛地应用于在线质量控制、在役 设备和关键零部件的安全检测之中。超声波探伤仪作为超声波检测技术实现的载 体，在超声波检测中具有重要的研究意义。为提高超声检测的可靠性和效率，开 发研制数字化、智能化、自动化、图像化的超声波无损探伤系统是当今无损检测 技术的必然趋势。 
论文以超声脉冲反射探伤理论为基础，利用CPLD强大的逻辑处理功能结合单 片机MCU作为系统的核心开发了一种数字式的超声波无损探伤仪。在论文设计的 数字化超声波探伤仪中，采用了模块化的设计方案，提高了系统的易维护性；选 用了低噪声、低漂移、高精度、高可靠性的集成电路芯片，提高了系统的可靠性； 在主控芯片上选择了低成本的单片机MCU和可编程逻辑控制器件CPLD，提高了 系统开发的灵活性。 
 在论文中首先对超声波检测技术和超声波探伤仪的发展进行了介绍，然后对超 声波检测的基本理论进行了探讨，并重点介绍了脉冲反射式超声波探伤仪的基本 原理。然后对设计中的数字式超声波探伤仪的总体设计及各功能模块进行了探讨， 确定了探伤仪设计的解决方案并对系统解决方案中的主控芯片和可编程逻辑控制 芯片进行了选型。之后重点研究数字化超声波探伤仪系统的硬件设计，包括超声 波的发射电路，接收电路，信号调理电路以及数据采集处理系统的设计和实现。 最后介绍了数字超声无损探伤仪系统的软件设计，对系统软件设计的总体流程、 超声波激励脉冲信号产生、数据采集系统的逻辑控制以及回波信号的数据处理进 行了介绍。 
 
关键词： 超声波，无损检测，数字化，信号调理，高速数据采集 

ABSTRACT 
 
As one of the main techniques in the nondestructive testing, the ultrasonic testing  has been applied in the area of online quality control and the security detection of the  in-service equipment and the key parts. The ultrasonic flaw detector is used as the  vector of the ultrasonic testing technique, and has important significance in the research.    The development of digital, intelligent, automatic and pictorial ultrasonic  nondestructive detection will definitely be the trend of the nondestructive testing for  improving the reliability and efficiency in the future. 
Based on the theory of ultrasonic pulse reflection method detection, this thesis  developed a digital ultrasonic flaw detector by utilizing the powerful logic processing  function of the CPLD and combining with the MCU. In the research, the design scheme  of modularization is employed in the design of the digital ultrasonic flaw detector to  enhance the modularization; the low noise, low drift, high precision, high reliability  integrated circuit chips are introduced to improve the reliability of the system;  the low  cost MCU and CPLD are adopted to boost the flexibility of the system. 
The thesis begins with the introduction of the ultrasonic detection technology and  the development of the ultrasonic testing, then discusses the theory of the ultrasonic  testing, especially on the theory of  ultrasonic pulse reflection method  inspection  ultrasonic flaw detector. After studying the collectivity design and the function modules,  it gives the solution that the MCU and CPLD are ascertained for the system. The main  body of the thesis studies the hardware design and the implementation of the ultrasonic  testing system , including the ultrasonic transmit circuit, receiving circuit, signal  processing circuit and the data acquisition processing system.Finally,it introduces the  software design, whole design process of the system, exciting pulse generation, the  logic control of the data acquisition system, and the data processing of the ultrasound  echo signal is also introduced and explained. 
 
Keywords: Ultrasonic, Nondestructive Testing, Digital, Signal Conditioning,  High-Speed Data Acquisition 

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