Research On Online Monitoring And Analysis System For Diameter And Roundness Of Multi-specification Expanding Pipe

High precision and intelligent workpiece measurement is the inevitable trend of the development of intelligent manufacturing production in the future,and visual measurement technology is the key technology to realize the intelligent control and detection of the diameter and roundness of the expanded pipeline and improve the measurement accuracy of the pipeline.Because the diameter and roundness of the pipeline constantly change in the process of expanding,in order to ensure the machining accuracy of the pipeline,the diameter and roundness of the pipeline need to be tested in real time,while the traditional pipeline measurement method needs to stop expanding before testing,which greatly reduces the production efficiency of the pipeline.Therefore,how to realize real-time online accurate measurement of pipeline in the process of expanding diameter is the key problem to be solved.In this paper,rapid and high precision measurement of expanding pipeline is realized by developing the experimental platform of expanding pipeline,calibration line scanning sensor,optimizing the processing algorithm of pipeline point cloud and constructing the fitting calculation method of point cloud outer contour.In the process of measuring the diameter and roundness of multi-specification expanding pipeline,the collection method of pipeline point cloud data is an important basis and premise for realizing high-precision pipeline splicing.Firstly,considering the different specifications and characteristics of pipelines in the actual pipeline measurement process,pipelines of different diameters are selected to build pipeline diameter and roundness measurement test beds,complete the mechanical system and control system of the pipeline measurement test beds,analyze the uncertainty of the measurement system by using the uncertainty principle,and design the software interface of the measurement system.It provides conditions for the follow-up pipeline real-time online measurement.Secondly,two different lifting line scanning sensors were used to collect calibration block point cloud data,and the sensor calibration parameters were solved by combining the least square method to determine the exposure and acquisition mode of the visual sensor.Wavelet threshold and signal-to-noise ratio algorithm were used to denoise and analyze the collected pipeline point cloud data samples.Finally,the random sampling consistency algorithm(RANSAC)and iterative nearest point(ICP)algorithm were used to eliminate the wrong point matching of the pipeline and obtain the external contour of the pipeline.The high-precision articular arm measuring machine was used to measure the pipeline,and the diameter and roundness of the pipeline obtained by the measurement system were calculated in combination with the numerical calculation method to verify the accuracy and reliability of the measurement system.The designed system is used to carry out measurement experiments on pipes of 400 mm,1000mm and 1600 mm.The system can achieve accurate measurement of diameter and roundness.The maximum error of diameter and roundness is no more than 0.266 mm and0.427 mm respectively,and the maximum repeatability error does not exceed 0.130 mm and0.170 mm respectively.It can meet the processing requirements of expanding pipes and provide an effective technical means for the accurate and rapid detection of diameter and roundness in the process of expanding pipes of different specifications and sizes.