Study On Online Detection System Of Conical Thread Based On Precision Image Processing

As channels to transport prtroleum,the tubing is widely used in oil field,and the quality of tubing threads's connection have great effect on normal oil production.At present,the thread measuring method is still staying in manual method,which has high error possibility and low precision.It is urgent to develop a more effective thread measuring system suitable for stable production.This paper introduces an instrument for auto-measuring parameters of outside screw based on non-contact measuring and image processing techniques.The instrument obtains 2-D data of the screw axis profile section by CCD with optical projection and machine driving,and then calculates out needed parameters.The measuring system researched is on the ground of optics,mechanics,electronics and mathematics.The main content of this thesis includes:principle of the instrument,image acquisition and preprocessing, screw image edge detection and calculate method of screw parameters.In software development,the SUSAN operator is used to detect the edge of screw image,and mathematical morphology and subpixel are also applied to process the edge.Least Squares procedure is employed to fit the exteral screw profile line. We can calculate geometrical parameters of the screw by the implemented system.