【作者】 兰爽；

【导师】 张永弘；

【作者基本信息】 大庆石油学院 ， 安全技术及工程， 2004， 硕士

【摘要】 油管在油田的应用量非常庞大，油管的圆螺纹连接质量直接影响油田的正常生产。以大庆油田为例，由于螺纹部位失效引起的检泵作业量在逐年上升，占各种检泵情况之首。如何采用一种行之有效的螺纹安全检测方法，是目前急需解决的问题。 针对目前油管螺纹形状参数检测技术中存在的问题，本文参照API对螺纹几何尺寸的有关规定，结合现有图像检测理论，提出了基于线阵CCD的非接触式检测方法，用来测量油管外螺纹的各项几何形状参数，并对其中的有关技术进行了分析研究。该方法对螺纹进行直接投影成像，以线阵CCD摄像头接收并采集到计算机内部，通过图像处理技术进行几何尺寸测量和分析。 圆锥螺纹的螺旋线对轴剖面内牙型的投影会产生遮挡，本文通过调整螺纹轴线的位置消除了遮挡作用，并提出了根据线阵图像判断待测螺纹是否处于理想位置的方法。为了得到完整的螺纹牙型数据，建立了计算机控制的纵向工作台，可以实现对螺纹投影的逐行扫描。计算机采集到的螺纹一维图像含有随机噪声，采用中值滤波法消除了噪声，改善了图像质量。针对螺纹一维图像具有阶跃性的特点，提出了基于差分法的边缘检测算法，准确地提取出螺纹牙的边界点。在原有二维螺纹图像测量理论的基础上，本文对一维图像的测量方法进行了探讨，根据螺纹轮廓的信号直接采集型值点参与拟合计算，以拟合轮廓进行尺寸计算。通过选用像元尺寸小、数量大的线阵CCD，可以一次摄取的螺纹牙数量大大提高，实现了在同一幅图像中进行螺纹各项尺寸的测量，进一步提高了螺纹参数的测量精度。 最后，编制了包括采集、图像处理和测量计算的检测程序，可存储原始数据文件、图像及测量结果报表。实验表明，本方法测量准确，精度高于API的规定，是测量油管外螺纹几何尺寸的一种有效方法。更多还原

【Abstract】 The tubing is applied widely on oil field, and the quality of tubing thread connection effects on normal oil production. In case of Daqing Oil Field, the amount of pump checking caused by thread failure is increasing year by year, which occupies the first place among all kinds of pump checking. So it is urgent to set up an effective thread measuring method for safety at present.Aiming at the problems in the measurement of tube thread parameters, the paper presents a non-contact measuring way which makes use of the current image measuring theory and is based on linear array CCD according to API definition about thread size. The key technologies in the method are discussed in the paper. The method take the projecting photos of thread by a linear array CCD camera, the photos are inputted into computer, then the thread image can be analyzed and the size can be measured through image processing.The spiral line of taper thread can shelter the projection of teeth in axial section. The paper studies to remove the effect by regulating the position of thread axis and gives a method to judge if the thread is in right place by its image taken by linear array CCD. In order to obtain the 2-D projection data, a longitudinal traveling workbench controlled by computer is set up to realize line by line scan. One dimension thread images collected by computer are processed to filter noise and improve quality. Edge detection based on difference algorithm is introduced, which is effective to the image with step gray scale and can extracts exact edge points of thread tooth. The measuring method of 1-D thread image is discussed based on that of 2-D image. The points on tooth contour gathered by edge detection are fitted to lines, and the tooth’s size can be calculate from fitted contour. The paper selects a CCD camera with small pixel and enough pixel number, which can take a projecting photo containing much more thread teeth and make it possible to measure all the main sizes only in one image, the measuring precision can also be improved at the same time.Finally, a testing program is developed with the function of data-collection , image processing and sizes calculation. The original data file, image processing and measuring result can be saved. The test shows that the system is accurate and its precision is higher than that of API gauge. Therefore, it is an effect way for tubing thread measurement.更多还原