Research On Key Technology And Surface Integrity Of Superalloy Blade Robotic Belt Grinding

Nickel-based superalloy blade is a typical turbine blade and its surface quality directly affects the service life and performance of aero-engines.The cast nickel-base superalloy blade has no positioning reference and uneven surface margin distribution.The manual grinding efficiency is low and the quality is difficult to guarantee.At the same time,the numerical control machine has high cost and limited motion space.Due to its low cost and high flexibility,robots have been widely used in various processing fields.However,robots have low motion accuracy,which limits their applications in the aerospace industry.In this paper,the problems of robot error compensation,blade calibration and machining trajectory planning for uneven surface distribution are studied and the key techniques for the nickel-base superalloy blade belt grinding are proposed.Meanwhile,in order to ensure the surface integrity of the blade,the process parameters of the belt grinding nickel-base superalloy are studied.The main research work of this paper is as follows:(1)The characteristics of weakening rigidity,low motion precision and elastic deformation of the nickel-base superalloy blade robotic belt grinding are analyzed.A grinding method with low elastic modulus to make up the machining precision is proposed and a belt grinding head structure with “N” axis is designed.Considering the weak rigid resonance characteristics of the structure,the modal analysis and harmonic response analysis of the structure are carried out so as to provide an experimental platform for subsequent belt grinding of blade processing.(2)Combining blade and grinding head characteristics,The calibration method of blade is carried out.In order to obtain the margin distribution,the blade margin is measured and the blade profile model is reconstructed.The blade machining path is planned and the margin distribution is obtained.The double vectors of contact wheel are controlled and a mathematical model of each joint angle of the robot is established.The "N" axis communication file and motion parameters are set and the robot processing program is completed.(3)In order to obtain blade processing parameters,the analysis of the influence of blade surface integrity is carried out.The orthogonal experiment of nickel-base superalloy samples is carried out and the influence degree of each process parameter on the surface of the samples is determined.A single factor experiment on linear velocity and grinding force is designed to study the influence of surface integrity of nickel-base superalloys so as to provide relevant basis for selecting the better process parameters of subsequent robotic belt grinding blade.(4)The nickel-base superalloy precision casting blade robotic belt grinding experiment is carried out.The influence of each grinding on the accuracy of the blade is analyzed.The surface morphology of the blade is observed and the variation law of the surface roughness of the blade is analyzed to verify the feasibility of the grinding process technology and process parameters of the nickel-based superalloy blade robotic belt grinding.