Precision Abrasive Belt Grinding Research Based On Contact Theory

As one of the key parts of aero-engine, cross section shape and dimension precision and surface integrity of blades have a critical influence on the performance of aero-engine. Aeroengine blades after milling or precision forging, have the characteristics of the allowance vary for machining and curvature big change across the surface. The traditional processing method is difficult to meet the technological requirements of machining precision, surface quality consistency and intelligent manufacturing of aircraft engine blade, and it is an urgent need to adopt the new processing method to solve the machining problems. Belt grinding have the impact of the grinding and polishing, the characteristics of process high flexibility and strong adaptability and the unique fitting effect in surface smooth transition, and it is especially suitable for weak rigid precision machining of complex surface. However, the current research on precision abrasive belt grinding mechanism is still not perfect. According to the characteristics of elastic belt grinding and aircraft engine blades, this article study on the mechanism and key technology of precision abrasive belt grinding based on contact theory. The main contents of this paper are as follows:① Considering the pyramid abrasive belt as research object, the model of abrasive grains is established; then, on the basis of remove material theory model of single grain, removal material simulation of grains is carried out, and it is analyzed that the impact of the contact pressure and particle number to the surface roughness of workpiece and the average depth of material removal. The belt grinding experiment of Tc4 titanium alloy which is the aircraft engine blade typical material, are carried out, and it is discussed that the different grinding parameters have the influence on the material removal rate and surface roughness; on this basis, according to the nonlinear regression method, the prediction model material removal rate(MRR) under constant pressure is established. It is set up for the next step to provide theoretical basis of surface removal contour(MRC) model.② It has analysis of the reason why the abrasive belt grinding contact state conforms to the basic assumptions of the Hertz contact theory, and research on the derivation process of the Hertz contact theory and half Hertz contact theor. On this basis, the abrasive belt grinding MRC model is established based on MRR. To the effectiveness of contact model and MRC model, it have MRC test and finite element analysis of contact between rubber wheel and the workpiece. Through finite element analysis of contact between the rubber wheel and the workpiece, it is investigated the influence of the contact wheel radius, rubber hardness, thickness ratio, contact pressure and radius of workpiece on the contact pressure distribution, and the models are verified by the contact test and MRC test. It is the theoretical basis of precise abrasive belt grinding.③ According to the characteristics of elastic deformation of the rubber contact wheel, the influence of MRC on the path interval and the step length is researched, and the approximate calculation formula of the final remove depth and the residual height are deduced. Based on this, a new method for the optimization of path planning and the grinding pressure put forward, and belt grinding simulation analysis of aircraft engine blade is carrid out based on this method. to provide technical support for precision abrasive belt grinding. It provides technical support for precision abrasive belt grinding.④In view of the difficult machining characteristics of aero-engine blades, belt grinding test and simulation of aero-engine blade are carried out applying the elastic contact model, the MRC model and the presented belt grinding path planning method. The applicability of the precision belt grinding path planning method is verified through the detection and analysis of the machining accuracy and surface quality of blade.