【作者】 李凯；

【导师】 王立权；

【作者基本信息】 哈尔滨工程大学 ， 机械电子工程， 2011， 硕士

【摘要】 油气输送管道由于处于特殊的工作环境中,因此管道对接环焊缝不可避免地会存在着缺陷,由此可能会为其作业埋下安全隐患,因此需要对输送管道的对接环焊缝进行检测。全自动超声检测(AUT)以其独特的优势成为管道环焊缝缺陷检测领域应用最为广泛的检测方法。随着我国近年来新建管线数量的急剧增加,为了保证管道环焊缝缺陷检测的可靠性并提高检测效率,研发智能化的超声检测设备已成为当务之急。本论文以国家“863计划”子课题“AUT检验设备国产化技术研究”为依托,对管道环焊缝超声扫查器的行走机构进行研究。本文首先确定了管道环焊缝自动检测设备的总体设计方案,进而对扫查器的机械结构和运动控制系统进行了简要介绍。基于扫查器总体设计方案对其导轨夹持行走机构和导轨的机械结构进行了细致研究。导轨作为扫查器的机械载体,起到联接和定位作用；行走机构主要包括四个部分：角度调整机构、夹紧自锁机构、驱动模块以及运动反馈模块。为了验证该行走机构的可靠性,本文设计并完成了与其原理完全一致的原理验证样机,同时进行了模拟扫查器沿环形导轨行走试验。试验结果表明自重24kg对其施加600N夹紧力时,行走机构能够可靠的沿环形导轨圆周运动。以试验数据为依据对主动轮与导轨的接触应力进行分析计算,并对导轨进行强度和刚度有限元分析。为了使扫查器沿环形导轨匀速运行以保证管道环焊缝检测的精度,本文建立了行走机构速度闭环控制系统的数学模型,并对其进行仿真,仿真结果表明该控制系统具有良好的精确性和动态响应特性；而后对控制系统的硬件和软件分别进行了设计,主要包括单片机控制模块,功率驱动模块和通信模块三部分,由上位机给微控制器预设扫查器行走速度,通过编码器将扫查器实际行走速度反馈给微控制器,微控制器将给定速度值与实际速度值进行比较,并通过数字PID控制算法调节直流电机转速,进而精确控制扫查器行走速度。基于理论设计本文完成了管道环焊缝超声扫查器工程样机,并进行了环焊缝缺陷检测试验,试验结果表明扫查器设计合理,缺陷检测效果良好,完全满足实际使用要求。更多还原

【Abstract】 The girth welds defect which is hidden threat against operation safety is inevitable as a result of the special working atmosphere of oil and gas pipeline. Therefore the girth welds of pipeline must be tested. Automatic ultrasonic testing(AUT) is the most widely used testing method for girth welds of pipeline because of its unique advantages. The amount of new built pipeline is increasing rapidly in these years, it’s of great urgency to research and develop intelligentized ultrasonic testing equipments which can guarantee the reliability and raise the efficiency of girth welds defect testing. This paper did research on traveling mechanism of girth welds ultrasonic scanning equipment based on national "863 Program"——"Research on Domestic Technology of AUT Equipment".This paper first established overall design scheme of the girth welds automatic testing equipment, and then made brief introduction of mechanical structure and motion control system of the scanning equipment.This paper then made intensive research on mechanical structure of orbit-holding traveling mechanism and orbit based on overall design scheme of scanning equipment. As the carrier of scanning equipment, the orbit has connecting and orientating function. The traveling mechanism is composed of four parts:angle adjusting mechanism, self-locking holding mechanism, driving module and motion feedback module.In order to verify the reliability of this traveling mechanism, a prototype which works in the same way as the orbit-holding traveling mechanism was designed and manufactured in this paper. And the experiment that simulating the scanning equipment traveling along the orbit was completed, which shows that the traveling mechanism can travel along the orbit reliably when it weighs 24kg and is exerted a 600N force. Based on this result, this paper computed the contact force between driving wheel and orbit and made finite element analysis of orbit strength and stiffness.In order to guarantee the testing precision of pipeline girth welds, the scanning equipment must travel smoothly along the orbit at a constant speed. This paper established mathematical model of traveling mechanism speed closed loop control system, and the control system simulation was carried on which proves that the precision and the dynamic response characteristic of the control system is good; and then the hardware and software of the control system was designed in this paper, including singlechip control module, power driving module and communication module, the ideal traveling speed is set by host computer, and the actual traveling speed is sent to microcontroller by encoder, then the microcontroller compares the given speed with the actual speed and regulates the DC motor rotation speed with PID control algorithm, finally achieving the goal that the traveling speed is controlled accurately.This paper completed an engineering prototype of girth welds ultrasonic scanning equipment based on theoretical design, and the experiment that testing defect of girth welds was completed, which shows that the design of scanning equipment is reasonable and the defect testing effect is good. The ultrasonic scanning equipment can fully meet the demands of girth welds defect testing.更多还原