Research On Geometrical Error Analysis Of Blades On Monolithic Impeller

Integral impeller is used in a wide range of applications such as in the energy, automotive,aviation, aerospace and other fields. While the impeller blades working under relatively poorenvironment, they need to work under high speed rotate, high temperature, high pressure environment.So the design and manufacture of impeller blades can directly determine the quality of the machine’sperformance, safety and life. Impeller manufacturing process due to the external environment,non-standard technology and other variety of reasons, will produce profile error, rotational symmetryerror and other variety of errors for impeller blades. It causes a great impact on machine’s noise,vibration and working efficiency. And the impeller owns complex blades profiles and is withrelatively large number blades. So how to detect and assess the quality of the blade’s profiles androtational symmetry error will pay more people’s attention.In this paper, the research on registration techniques between the impeller point cloud data andthe CAD model, the technology on blade surface feature extraction and blades rotational symmetrydetection are studied. On the basis of the above key algorithms and techniques, an error analysissystem based on Opencascade platform is developed. The main research contents and innovativepoints are summarized as follows:(1) First, methods are presented for registering the impeller’s measure data and CAD model date.The registration process include coarse registration and fine registration. For coarse registration,several commonly used methods are implemented and compared. For fine registration process, anacceleration method based on the bounding box to find the nearest point is proposed.(2) Research on getting the impeller’s blade cross-section data is presented. The parameters ofvarious parts of the blade section are extracted by fitting each part of blade section. To obtain thecharacteristic parameters error of blade’s section, the parameters between measurement data andtheoretical data are compared.(3) An novel approach is proposed for analyzing the free curved surface rotational symmetryerror. This paper proposed a rotational symmetry geometric error analysis and calculation methodunder surface explain and centre explain.(4) On the basis of the above key algorithms and techniques, and utilizing the Opencascade opensource library, a impeller blade cross section error and rotational symmetry error detection andanalysis software is developed. The encouraging experiment shows that the related theories of thisthesis are correct and the software system is practical. This paper research can calculate the impeller blades cross section parameter errors androtational symmetry error effectively. Variety of impeller blade models come up with better results.