Study On 3D Mixture Measurement Technology Of Centrifugal Impeller Of Small Turbine Engine

Turbojet engine is the main source of power for aircraft.As an important part of turbojet engine,The processing quality problem has been widely concerned by domestic and foreign scholars.At present,adding and subtracting material processing has become one of the important processing means of centrifugal impeller and other complex components.In the process of machining,the three-dimensional geometry information of the impeller blade must be strictly checked and controlled to ensure the efficiency and safety of the engine.Therefore,how to accurately and efficiently measure the complete three-dimensional shape of the blade and obtain its three-dimensional digital morphology data is very important for the further optimal design and machining of the impeller blade.In this paper,the centrifugal impeller is taken as the study object.Based on the technical difficulties existing in the measurement of the centrifugal impeller at present,a hybrid measurement scheme combining contact measurement with binocular vision measurement is proposed.The main work content of this paper includes the following:(1)The overall measurement scheme of centrifugal impeller was planned.Firstly,the characteristics of the parameters of the integrated centrifugal turbine blade disc were analyzed,and the measurement planning of the centrifugal impeller was carried out by using the technical characteristics of on-machine measurement and visual measurement.Then the measurement area of the surface of the centrifugal impeller was divided according to different measurement methods to achieve a complete measurement of the three-dimensional data of the centrifugal impeller.Finally,the functions and characteristics of the on-machine measurement system and the visual measurement system were introduced.(2)The simulation and actual measurement of centrifugal impeller on-machine were realized.Based on the optimized centrifugal impeller CAD model,the on-machine measurement simulation was carried out by using the simulation software PowerInspect,and the real-time on-machine measurement experiment of the centrifugal impeller was carried out on the five-axis material addition and subtraction machining center.(3)Binocular vision measurement was carried out based on the center of the circle feature recognition algorithm.The mathematical transformation relationship between camera coordinate system and robot coordinate system was established by camera calibration and hand-eye calibration respectively.An algorithm for recognizing the center of a circle was proposed to enhance the surface information of the measured object by pasting circular markers.The vision measurement of engine blade was realized by using the multi-view 3D reconstruction principle,and the validity of the vision measurement was verified finaly.(4)The mixed measurement data of the centrifugal impeller were fused.The centrifugal impeller passage was taken as the common measurement area of the two measurement methods,and the coordinate transformation relationship between the onmachine measurement data and the visual measurement data can be obtained by using ICP algorithm.Finally,the data of the two measurement results were fused.Compared with the white light scanning data,the precision measurement with a preliminary deviation of about 0.058mm and a standard deviation of about 0.041mm can be achieved.