An investigation on measurement accuracy of digitizing methods in turbine blade reverse engineering

Abstract

Measurement and quality control of turbine blades is critical to the successful operation of power plants. It has a key role in manufacturing and reverse engineering. Novel technologies continue to be developed to measure parts with complex geometries, such as turbine blades. Digitizing techniques, using both contact and noncontact methods, are used. Selecting the most appropriate digitizing method for a turbine blade requires consideration of the measuring performance of the alternative methods, including criteria such as accuracy, speed and cost. This study seeks to evaluate the practical accuracy and efficiency of various contact and noncontact digitizing methods through measurement and associated quality control of a complex part, that is, a turbine blade airfoil. Four popular technologies, using distinct underlying measurement methods, were chosen to measure a Frame 5 gas turbine blade, namely, a touch trigger probe mounted on a Zeiss coordinate measuring machine, a touch scanning probe and a spot laser probe separately mounted on Renishaw coordinate measuring machine and a linear laser system from ZScanner. The measured point cloud resulting from each method was then used to reconstruct three-dimensional computer-aided design models of the blade. The accuracy of each measuring system was evaluated against the original blade. The evaluation incorporated a comparative study of design parameters derived from the point cloud and reconstructed surfaces associated with each measurement method. The maximum error of point clouds were 2123, 2530 and 2173 mm for the ZScanner linear laser, Renishaw spot laser and Renishaw touch scan, respectively. These measured errors indicated higher accuracy from linear laser method than spot laser scanning and touch scanning methods. Furthermore, the achieved standard deviations of 42, 170 and 269 mm for point clouds of ZScanner linear laser, Renishaw spot laser and Renishaw touch scan, respectively, showed that the manufacturer reported that information cannot be always reliable.

Nondestructive inspection of gas turbine blades by active thermography using different fluids

“…1 The most crucial parts of a gas turbine, are turbine blades. [2][3][4] Efficiency of a gas turbine engine is directly related to the inlet gas temperature and pressure. 3,5 In order to enhance the efficiency of a turbine, the inlet gas temperature and pressure shall be elevated.…”

Phase measuring deflectometry for obtaining 3D shape of specular surface: a review of the state-of-the-art

“…Although CMM has the drawbacks of high cost, low speed, and scratching of the surface, 29 it is still the most widely used method for specular surface measurement because touch probes are highly accurate for dimensional inspection. 30,31 However, traditional CMMs are limited due to a lack of rotational degree of freedom, so they cannot be used for digitizing complex and free-form surfaces. 32 Interferometry [20][21][22] and deflectometry [15][16][17][18][23][24][25][26][27][28] are two competitive *Address all correspondence to Zonghua Zhang, zhzhang@hebut.edu.cn; zhzhangtju@hotmail.com methods among the noncontact measurement methods because of their high measurement accuracy and resolution.…”

Research on blade grouping method for array machining

“…Each engine has hundreds of blades, and their manufacturing workload accounts for about 25%–40% of the entire engine’s manufacturing process. 1,2 The production schedule of blades directly combines to produce the whole engine, and the processing efficiency is important. There are many blade processing methods and the most commonly used is multi-axis CNC machining.…”