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Introduction
The assessment of the geometric accuracy of aircraft engine blades is one of the key ways to verify the precision of a technological process and should be carried out with the use of appropriate methods and tools. In case of aircraft engine hot section blades, there is a necessity for the use of coordinate measuring techniques (Budzik, 2013; Kawalec and Magdziak, 2012), such as a three-dimensional (3D) scanning of objects surface by using structured blue light, e.g. ATOS GOM system used in measurements.
Computer-aided coordinate measurements allow a relatively quick analysis of the accuracy of the product in relation to the 3D-computer-aided design (CAD) model and the nominal values specified in technical documentation. The integration of measurement methods with CAD systems, computer-aided engineering (CAE) systems and computer-aided manufacturing (CAM) methods, including rapid prototyping (RP) CAM/RP, allows a significant acceleration of designing and manufacturing processes of new or upgraded constructions (Rokicki et al., 2014; Wieczorowski et al., 2010; Gajdos and Slota, 2013). The analysis of blade geometry by using the ATOS GOM system can be developed in relation to the nominal CAD/STL model or a reference model obtained from previous measurements, and it can be stored in the STL format. The ATOS system software – “GOM Inspects” - allows the conduction of various analyses in a global system, given cross-sections, and additionally, special analysis of particular dimensions by using the “Analyze Blades” module (Figure 1) (Hu et al., 2011).
In addition, the integration of CAx/RP systems with measuring methods allows the conduction of a detailed analysis of the manufacturing process, from the stage of standard models prototyping with RP methods to the final product (Liu, 2008). Models manufactured using RP methods may be used in the product design process and the study of process parameters, eventually to create model sets, ceramic shell moulds and blades castings (Sederberg and Parry, 1986; Szeliga et al., 2014a, 2014b).
3D-CAD and 3D-STL blade models
Computer-aided measurement methods allow to perform the accuracy analysis of a product in relation to the 3D-CAD model. Turbine blades designed in 3D-CAD systems require the use of a hybrid model that combines surface and solid modeling (Witek, 2014). The first stage of airfoil modeling is to determine the curves for...