Trajectory Planning For Blades Automatic Welding Restoration Based On Welding Process Analysis

The blade is the core parts of aero engine, which known as the “heart of the engine”.The blade usually works under the environment of high temperature and high pressure.Having been used for a period of time, the blade would be damaged with corrosion and creep shrinkage hole. In the engine repair manual, welding repair on the blade of high energy beam is recommend. However, the performance in strength, size precision,anti-fatigue requirements of the repaired blade is rigorous. Reliable welding numerical control equipment and adaptive application software are used in blade repair. With the development of the theory of free curve and surface, the requirement for the NC system is becoming higher and higher. In order to realize the integration and intelligent of CAD/CAM/CNC, the NC system can interpolate the parametric curve directly. Considering of the advantages of flexibility in designing, non uniform rational B-spline(NURBS),which is a stable algorithm, is outstanding in many parameter curves. The algorithm has driven it into a high level in design, analysis and calculation of curve and surface. Therefore its application in the field of mechanical processing was greatly speed up. The advanced technology of real time interpolation algorithm of NURBS has become a hot and difficult problem in the current numerical control technology.A method is proposed which is for optimizing the welding speed. The method is based on blade welding process analysis. So you can get a better welding speed, low welding residual stress and distortion. The speed is also as a basis for planning the welding path.The NURBS curve interpolation technique proposed in this paper, which combines chord error and Taylor Formula, can directly express the complex welding path curve, and improve the blade welding precision, also improve the ability of expression and interpolation to path curve.The main work in this paper includes:Through the mathematical model of NURBS and the experimental data, the welding path curve of the blade was established. Three dimensional modeling of the blade was built,and the welding process was simulated, temperature field and stress field of the simulation was analyzed, as a result, the welding parameters was optimized. Then the welding speed optimized was obtained. Used the method of welding speed and the Taylor series expansion for the densification of curve parameters, the parameter increment was obtained. Gradually the parameters of curve interpolation of welding path were realized. Then correspondencebetween each point and the parameters or time of the path curve was obtained, trajectory planning completed. The process of welding of blade was simulated by simufact-welding.Finally simulation curve interpolation process, analysis the relationship between the interpolation precision and parameter increment, and the trajectory planning of the curve were realized by using MATLAB.