The Research On The Repaiirng Method Of Drill Collar Taper Threads

In drilling tasks such as oil drilling, geological exploration,as the hole deepens,deformation and failure of drill collar joint of thread often occur.For drill collar joint taperedthread came up local failure occurs,can be cut to part of the male,and track along the originalthread,processing the lighter thread groove to design depth,in order to complete the internaland external taper thread together again.This can enhance the service life of drill pipe, drillcollar, has a high economic value.This issue under the principle of thread process,obtained the remediation of the taperthread,the relationship between end face and form of thread analyzed and calculated.According to the characteristics of taper threads,derivation the formula that the drill pipe jointworkpiece positioning in the machine coordinate system.To obtain the spiral positional arguments put forward four locating scheme:Precisionmeasurement tool to manually get the tool parameters;Proximity sensor to find the central lineof adjacent threads,Laser two-dimensional laser scanning to obtain profile information,Facefeature extraction based on image processing technology.The first scenario is that according tothe existing modification access to specialized measurement tools for taper thread measuringprecision of measurement tools; the second scenario is a specially designed semi-automaticlocating device; the third scenario is that according to the principle of availabletwo-dimensional laser scanner to get job imformanton to complete the repair parameter.thefourth programme is to analyze the face image based on the head of Helix around the pointand difference in geometry,texture,gray metal,came up in the position of the machinecoordinate system.and finally chose Face feature extraction based on image processingtechnology.To obtain the end face parameter,the topic analysis of the geometry features that thethread workpiece along a perpendicular to the axial sectioning.and aimed at the actualprocessing thread model workpiece,use of fingerprint feature extraction algorithms,thread endface image feature was pick up.eventually Characteristics of end surface of the workpieceimage was extacted,and according to the characteristics of the image coordinates, re-fittingouter circle, calculate radius and centre location, using the coordinate parameters to completeend image vectorization,thus gaining an numerical controlled thread repaired parameters.Last invoked thread repair instructions and by the signal of circumferential directioncompensation to control the start cutting time to complete the taper thread CNC repair work.