Method for quickly measuring blade of large-sized water turbine

Abstract

The invention discloses a method for quickly measuring a blade of a large-sized water turbine, which is characterized by comprising the following steps: firstly, sticking a mark point to the surface of the blade, then shooting a group of photos from different angles as measured primary data, and inputting the data to a computer to carry out analytic processing; by carrying out image detection for the group of photos in a measurement software, identifying the mark point in each photo and positioning the center of the mark point, and matching the mark points with the same name; finally, reconstructing a three-dimensional coordinate of corresponding object points according to a plurality of two-dimensional coordinates of the mark points, fitting a sparse framework model of a target by the reconstructed three-dimensional mark points, then scanning the surface of the blade block by block by using a binocular grating scanning method to acquire a local dense point cloud, and aligning the dense point cloud to an overall coordinate system according to the local mark points to acquire a dense point model of the blade; and by comparing the dense point model with a CAD designed model after aligning, calculating a three-dimensional processing error of the surface of a workpiece.

Description

technical field [0001] The invention relates to a method for rapidly measuring blades of large water turbines, in particular to a method for rapidly measuring the size and profile of blades of medium and large water turbines using visual measurement technology. Background technique [0002] For expensive large hydro turbine units, the blade is the "heart" of the hydro turbine, and its surface quality and manufacturing precision will directly affect the hydraulic performance, power generation efficiency, operation stability and service life of the entire unit. However, since the profile of the large water turbine blade is a complex free-form surface, its volume and weight are huge, so in the process of manufacturing and processing, the full-scale detection of the overall size and profile of the blade has always been a difficult problem in the industry. [0003] The literature "Research Status and Development Trends of Hydraulic Turbine Runner Maintenance Equipment" (He Qinghu...

AI Technical Summary

Problems solved by technology

The combined templates used in the three-dimensional template method are handmade, have poor rigidity and are easy to deform, and have been gradually eliminated.

Although the three-coordinate measuring machine has high precision, it has high requirements on the measurement environment, is not portable, and has a small measurement range; especially the giant three-coordinate measuring machine is extremely expensive, and it is difficult to place and adjust the turbine blades on the three-coordinate machine, which requires time-consuming work in the early stage Establishment of detection coordinate system and measurement programming

However, due to the limitations of computer computing speed and image acquisition accuracy, no actual detection system has been applied.

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