Chord-line-based aviation thin-wall blade machining torsion degree error measurement method

Abstract

The invention discloses a method for measuring blade machining torsion degree errors. The method comprises the following steps of: intercepting a plurality of cross sections respectively for a to-be-measured blade and a blade design model, and generating corresponding point cloud data; extracting the generated point cloud data so as to acquire a convex hull; according to the obtained convex hull, solving the chord line parameters of each cross section of the relevant blade measurement model and the blade design model respectively, namely the two-end-point coordinates of a chord line; according to the solved chord line parameters, calculating the required rotation angle when each cross section of the blade measurement model and the corresponding cross sections of the blade design model are overlapped, thereby obtaining the torsion degree errors of each cross section of the to-be-measured blade. The invention also discloses a corresponding improved method for extracting the convex hull. According to the invention, the torsion errors of the blade can be rapidly and accurately measured in the machining process, also the measured sectional surface torsion degree error result can be taken as an index for evaluating the blade machining quality, and the blade machining quality is improved correspondingly.

Description

technical field [0001] The invention belongs to the technical field of blade processing, and more particularly relates to a method for measuring the processing distortion error of blades. Background technique [0002] Blades are widely used in aviation (such as the overall impeller of aircraft engines), nuclear power (such as steam turbine blades), ships (such as large propeller blades) and other industries that are related to the national economy and people's livelihood. The profile of the blade is generally a complex curved surface, and the processing procedure is relatively complicated. The quality of the profile has a decisive impact on the performance of the engine, and it enjoys the reputation of the "heart" of the aero-engine and steam turbine. [0003] Parts such as blades have technical characteristics such as strong distortion, thin-walled parts, easy deformation, and low damage. How to quickly and efficiently inspect the quality of their multi-axis CNC machining h...

AI Technical Summary

Problems solved by technology

These two methods are offline detection methods, which have slow measurement speed, less information, large human errors and too many unmeasured areas, which greatly affect the efficiency of blade detection.

With the development of optical measurement technology, non-contact measurement methods can be used to detect the blade profile, correspondingly overcome the shortcomings of traditional manual clamp measurement method and CMM measurement method, but the defect of non-contact measurement is: it is based on The two-dimensional image is used as input, and the third-dimensional coordinate value is calculated by using stereo vision and phase profilometry. Due to the limitation of the measurement distance, the directly collected point cloud reflecting the surface properties of the blade may have different scale deformations under the three-dimensional coordinates.

Judging from the measurement of the current aero-engine thin-walled blade manufacturers, most of them focus on the detection of the blade profile error, ignoring the analysis of the blade profile distortion, while the shape of the cascade channel and the initial aerodynamic parameters control the flow of the entire flow field , has an important influence on the aerodynamic, strength, vibration and dynamic performance of the blade

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