Research On Blade Robot Polishing Based On NURBS Surface Fitting

The blade is an important core part of aeroengine.It has the characteristics of free thin-walled surface and weak structural rigidity.It is a typical difficult-to-machine material.Therefore,precision grinding and polishing are usually used as the last finishing process to ensure its surface quality and Surface accuracy.However,due to problems such as vibration and deformation during the machining process,the blades after grinding and polishing have uneven distribution of margins,and it is difficult to fully guarantee the surface accuracy.Therefore,in response to this problem,this paper firstly studies the blade surface reconstruction technology and the surface error evaluation technology,and develops the blade path planning method,offline programming software and data processing platform based on the error analysis results,and finally builds the robot belt The grinding platform has been experimentally verified.The main research contents of this paper are as follows:Aiming at the problem of surface reconstruction of metal blades,research the interpolation fitting and approximation fitting methods of NURBS curves and surfaces,explore the optimization method of NURBS curve and surface weight factors based on genetic algorithms,and perform surface fitting on the blades to improve the weight of NURBS surfaces The construction accuracy provides a basis for subsequent blade error evaluation and offline programming.In order to evaluate the error of the curved surface,an error analysis model of Newton iterative algorithm based on the division of extreme value neighborhood is proposed.Explore the radius compensation method based on the normal vector of the curved surface and the simplex method of unconstrained optimization,and use this method to perform probe radius compensation and coordinate system matching on the three-coordinate measurement data.The experimental results show that the simplex method makes the fitted surface and the theoretical surface have a higher degree of matching.The path planning method is studied,and a step length calculation method based on discrete parameters and step length restrictions is proposed.The error analysis of the blade surface is carried out.Based on the error evaluation result of the surface and the processing parameters,the path planning of the blade surface is carried out.Experiments show that this method can accurately remove different margins.Designed and developed a data processing software platform based on OpenCasCase and VS2013.The platform implements functions such as surface fitting,surface error analysis,offline programming,and display.The blade grinding experiment was carried out using an offline program,and the experimental results showed that the machined blades after grinding met the accuracy requirements.Experiments prove that the surface fitting and error analysis of the software platform are correct.