Research On Variable Pressure Abrasive Belt Grinding Based On The Curvature Of Workpiece

Parts with free-form surface such,as blade,are the key components in many institutions.Because of their complex surface and the change of surface curvature,they are very difficult to process.Besides,with the development of science and technology,there are higher requirements for the machining efficiency and machining quality of the parts.In order to improve the existing grinding way(constant pressure grinding),which would produce the phenomenon of nonuniform removal quantity,A new method called variable pressure belt grinding is presented in this paper.By controlling the normal grinding force exerted on every point with different curvature when grinding free-form surface.Obtaining the uniform material removal quantity.Study of this thesis is mainly reflected in the following aspects:(1)Assuming the contact between the abrasive belt grinding wheel and workpiece conforms to the Hertz contact.A mathematical model of removal depth based on Preston equation is established,and the model takes the factors such as the curvature;the normal grinding pressure and the grinding speed into account.Then coefficient formula of Preston equation is deduced,and the coefficient is obtained by fitting experiment data.(2)According to the experimental conditions,the CAM is selected as the experimental object in this paper.The contour of the CAM is designed based on sinusoidal function rule.Then the curvature of each sample point of CAM contour is calculated in according of the cubic spline interpolation function with MATLAB.The formula of pressure angle of CAM is deduced,and then pressure angle of every sample point is obtained by the formula.(3)Some improvements are made for existing workbench to place CAM.The important parts of the mechanism are chooses reasonably,Then modeling;assembly and interference inspection of institution are completed with Solidworks.(4)The variable pressure grinding control system is established.The components of the system are selected reasonably.Based on Panasonic PLC,the open-loop and closed-loop control program are wrote respectively.The closed-loop program mainly adopts the method of fuzzy PID controller,and PID parameters can be tuned by itself online.The simulation is organized by Simulink of MATLAB.The grinding experiment is conducted with open-loop control system?(5)Experiments are designed to validate theoretical model of this paper,mainly including the determination experiment of friction system;measurement experiment of the Preston coefficient and measuring experiment of the grinding depth.According to the experiment data,the rationality of theoretical model of this paper is analyzed.