Research On NURBS-based Turbine Blade Modeling And Measuring Technology

Along with our country electric power industry’s fast development, The demands of power generation equipment such as steam turbine and so on is increasing unceasingly, the Blade as the main working parts of turbine generator equipment, not only of which the quantity is very large, but also long-term working in high temperature, high pressure, large flow of wet steam cycle of bad environment, of which machining surface quality directly affect the turbine blade surface corrosion and strain state,so requiring high process precision.Because the blade geometry shape is complex, each Section line is not same from the tip to the bottom of the blade, and each section profile is descripted generally through large number separate spots, therefore the blade profile measuring is quite difficult, having the typical representation, and has been attracted much attention.But in the actual production blade’s measuring has the following difficulty:the general measurement software unable to accomplish blade’s CAD modeling function, need the help of other CAD software,and through a format conversion read the CAD model. As the work nature of Turbine blade,except blade section error also must satisfy some other parameter index, however the general measuring software does not have such data analysis ability, And that must be ensured by other methods.In order to solve the problem that blade measuring efficiency is low and that measurement error analysis is difficulty, this article has completed a set of collecting blade modeling, the examination and the error analysis through the UG secondary development.The software system mainly might realize the following function:Useing the NURBS structure blade section line, By reconstruction of inletting edge, trailing edge completing smooth connection of inletting edge^trailing edge and back arc、inner arc,and completing the blades rapid modeling; Because the workpiece surface error,The piece coordinate system being building according to the workpiece surface does not coincide with the theory coordinate system, The least squares method is used to realize the alignment of the work piece coordinate system in the article, And completing the blade measuring path planning, generating automatic measurement procedures; the genetic algorithm is applied in the blade measuring data processing to complete the alignment of the blade surface, improved the measurement accuracy and providing many other indexes for the blade quality evaluation, such as blade section error, greatest thickness circular error and section core error and so on.The develop of the system is based on UG NX4.0and VC6.0++as the development platform, and is Completed by UG/OPEN API and the UG/OPEN Grip joint development, Finally, the system is verified through the type BL400producted by wuxi some blade plant and has achieved the desired results.