Research On Radius Measurement And Center Positioning Method Of Small Angle Arc Parts

With the development and advancement of aerospace manufacturing technology,precision testing of small-angle arc parts is required in the production of aero-engine parts.For example,in the production process of parts,a lot of large tooling or fixtures are needed.These tools or fixtures sometimes have round references with a short radius of a circular arc.These benchmarks need to measure the radius of the triangle by three coordinates,or even It is necessary to locate the center of the missing circle.Sometimes it is necessary to measure the concentricity of the two missing circles relative to the position of other measurement references.Although people continue to improve the accuracy of measurement systems and the development of test software,expensive investments have only achieved limited results.In this paper,the research on the effective measurement method based on the coordinate measuring machine is carried out for the measurement of the radius of the small-angle arc parts and the positioning of the center,in order to provide a new detection method and accuracy evaluation method for the measurement of small-angle arc parts.In this paper,the small angle arc part measurement method and its application at home and abroad are reviewed.Then,according to the actual measurement demand analysis of the foureight-stage static blade T-plate,the typical measurement method based on the coordinate measuring machine is deeply studied.The measurement accuracy,measurement uncertainty and their applicable range are analyzed.The theoretical analysis and mathematical model are constructed for typical measurement methods such as bow height chord length method,scan data fitting method and radius determination coordinate system translation method..Secondly,under the guidance of the theory,the experimental verification is carried out,and the arc-shaped experimental parts with high precision such as the standard ring gauge are determined,the steps and sequence of the experiment are established,and then the corresponding experimental data are processed according to different measurement methods,and various The method performs systematic analysis and comparison,and points out which method should be used under certain conditions to provide theoretical guidance for practical production applications.On this basis,in order to meet the measurement accuracy requirements of the four-eight-stage stationary blade T-plate,a comprehensive measurement scheme using various measurement methods is proposed to improve the measurement accuracy of small-angle arc parts in practical applications.Finally,the research results are applied to the production and assembly process of the four-stage eight-stage stationary blades of the turbofan engine,which solves the problem of the size and shape error detection of the production site,and also ensures the reliability of the assembly and shortens the four-level-The eight-stage stationary blade T-plate machining cycle and the assembly cycle of the entire four-stage eight-stage stationary blade segment.Therefore,the research work is very important for the production and assembly process of the four-stage eight-stage stationary blade segments of the turbofan engine.