Research On Measure Method Of The Precision Of Large-Diameter Straight Welded Pipe

Large-diameter straight welded pipe is widely used in industrial applications, and the using scale is growing recently, but the measuring of the shape and position accuracy faces with difficulties when the pipe diameter is expanded. This subject is aimed to establish a large-diameter straight welding steel pipe spiral rotation measuring solution for the large-span, large-diameter, and large-load steel pipe measuring, and using a new error separation method to improve the measurement accuracy, which improved the efficiency of the measurement and evaluation process, and with the help of the simulation results the principle of the method is verified.Firstly, the study on the measuring method for the single-section radial error of the large-diameter welded pipe. Basing on a broad access to relevant mathematical model information, this paper studied and simulated the resources of error and the error separation principle of the plane three-point error separation model. And the plane three-point error separation model is taken out on solving the circumgyration error separation problem of large-diameter welded pipe, which can be used to get the configuration measurement of the pipe end. The premises and assumptions of the model are given after a full analysis on the limitation of plane three-point model in the field of cylindricity and measuring-continuity.Secondly, the study on successive measurement taken on large-diameter straight welded steel pipe. By analyzing the revolution error components of the cylindrical workpiece, related technical parameters of the five-point model is calculated, which is based on a simplified movement. Basing on this the five-point helix trail error separation model is proposed, which can make successive measurement on this kind of pipes. By the same time, the effect, that comes from the irregular distribution of sampling points acting on the separation error, is analyzed, so are the corresponding solutions.Thirdly, a given surface parameters 3-D welded pipe simulation model is established and several simulation analysis is taken out on it. The accuracy of the method is verified by the simulation and analysis done on three-point method, which compared the advantages and disadvantages of time domain, frequency domain solutions. The result come out that the computing error has no relation with the solving process. Another kinematic simulation experiment is taken out on the five- point model, which comes out that comparing with a normal method the symmetrical discrete data processing method is more effective in separating the error. It also verified that the five-point model is correct. In addition, the paper also raised several other programs to improve the measurement accuracy of the five-point model.