【作者】 曲政；

【导师】 王石刚；

【作者基本信息】 上海交通大学 ， 机械设计及理论， 2009， 硕士

【摘要】 系泊链是用于海洋结构物定位与系泊的重要部件,在生产过程中,其焊缝位置需要接受严格的超声探伤。人工方式探伤存在误判和漏判的问题,因此需要设计一套自动检测系统,能够可靠地实现对系泊链焊缝的超声扫查任务。自动超声检测相关的系泊链特点,可以从三个方面各提炼为三点。链条是环环相扣的,可见:超声检测区域不连续,焊缝方位不确定,整体连接非刚性;链环是弯制成圆的,可见:环臂形状有变化,横档区域有限制,环冠套接有干涉;材料是锻造而成的,可见:表面粗糙度大,扫查区域可能存在凸台凹坑,链环面也不洁净。系泊链的这些特点给自动超声检测系统的研发带来一系列难题,需要深入分析解决。在以上问题中,本文主要致力于解决系泊链自动超声检测系统研发的机构方面的问题。其中重点工作如下:1.用塔架式超声检测工作台,解决系泊链链条柔性问题。通过各主功能和辅助功能模块的位置和运行的配合,可靠地实现系泊链自动超声检测的基本功能。2.用大粘度耦合剂的接触式探伤方法,解决系泊链链条表面粗糙度大的问题。通过多种探伤方式的比较,结合工件实际情况,自动化探伤系统选择了与系泊链人工超声探伤相似的方法。3.用转换工位机构,解决系泊链链条焊缝方位问题。链条送进、周转换位、升降找位和横进入位,这四个外围动作各自独立驱动,相互配合,使扫查器逐个对准链条上各链环的焊缝扫查区域。4.用内部周转和轴进机构相配合实现横方形超声探头扫查路径,解决系泊链普通有档链环的横档干涉问题。通过多种机构的分析比较,证明半环轨道和拖板相配合的周转往复机构,能够可靠地引导探头周转扫查运动。5.用探头杆的一个伸缩自由度和探头架的四个转动自由度来适应链环曲面,解决链环环形变化问题。这些相互配合的自由度,实现了探头对链环的良好贴合。6.用静力分析模型,解答了扫查器结构的悬臂和偏载问题。通过实际参数的测量、约束定性分析和程序承递求解,用计算数据说明了关键结构件的受力情况,证明零部件可以满足结构受力要求。本文通过技术方法比较、功能模块分析、机构方案选择和力学模型计算等方法,解答了系泊链自动超声检测系统的机构问题,给出了一套能够可靠实现探伤功能的系统机构方案。所得结论可以用于后续详细设计,所用方法可供相似系统的研发工作者参考。更多还原

【Abstract】 Mooring chains are important components for offshore structures, and need to be well tested by ultrasonic in the production process. The manual ultrasonic testing cannot avoid the problem of missing or misjudging the fault, thus an automated ultrasonic testing system for mooring chains is calling, which can perform complete scanning and consistent gauging.The development of this system must analyze and solve some special problems which emerge from the mooring chains’special characters. First, rings link to each other to make a CHAIN: the scanning sections are discontinuous, the welding orientations are irregular, and the series of links are flexible connector; Second, bars are bent to an oval shape, looped together and welded shut to make a RING: the arm shape is not cylinder, the stud is an interfere of scanning, and the link section of the two rings limits the space of scanning mechanisms; Third, forging metal are manufactured into mooring chains’SURFACE: roughness is significant, convex and concave units sometimes emerge, and the scanning face is not clean.Among all the considerations in developing the automated ultrasonic testing system, this dissertation focuses on studying the mechanism problems corresponding to the mooring chains specifications. The major achievements are listed here:1. Suspend the chains on tower platform with multi-layers for ultrasonic testing, resolving the problem of flexibility of chain connector. The major and auxiliary function modules operate in coordination on the platform, to implement the basic goal of automated ultrasonic testing work.2. Touch the rings directly with angle beam ultrasonic probe, which is assisted by high viscosity couplant, resolving the problem of surface roughness. By comparing a variety of testing methods, and investigating the actual condition of the workpiece, it finally chooses similar methods with the artificial testing.3. Change working post to access the mooring chains’each link, resolving the problem of weld orientation. The mechanism diagram of circumferential, axial and lateral direction movement illustrate the detection configuration’s possibility and effectiveness4. Scan the welding section by square-cross track with half circumferential and step axial mechanisms, resolving the problems of space limitation of rings. By comparing various structure, choose half circle orbit and carriage to well perform the circumferential scanning action.5. Adapt the camber with one slide and four rotate local degree of freedom, resolving the problem of ring’s shape changing. These freedom and the spring, achieved the good touching condition between the probe and ring’s surface.6. Calculate the constraints of scanning device with its static mechanic model, resolving the anxiety about the scanning mechanism’s structure problems of cantilever and eccentric load. With customized parameters and communicated data, mechanical components and industry part can be design and chosen in detail.This dissertation, by comparing various testing methods, analyzing function relativity, choosing mechanisms and building mechanic model, resolved the special problems of mooring chains, and presented a sound mechanism system for automated ultrasonic testing. The results here can be used in further development of this project, and the methods might do favor to researchers while studying similar problems.更多还原