Research On Error Analysis And Modify Method Of The Blade Surface NC Machining

Milling is a widely used machining method in aeronautic and aerospace industries and other industries for machining blade. However, in actual machining process, machining error caused by the cutter deflection influences the machining accuracy and the surface quality of the blade. With the development of machining technology, the precision standard of the blade gets higher and higher. Consequently, the prediction of the machining error in blade milling process and the investigation of active compensation can improve machining quality and processing efficiency significantly. This thesis studies the influence of the cutter deflection in blade finish machining, accurately predicts the cutter deflection, adopts effective active compensation based on the predicted machining error, and the processing quality is improved. The main work is as follows:1. Use CAD/CAM software for the blade surface modeling, plan CNC machining route.2. Calculate the cutting force, the cutter deflection and the surface machining error of the whole finish machining. First, established the ball-end cutter cutting force calculation model based on the differential theory, and then apply the analytic geometry theory, get the cutter line geometric equation of the ball-end cutter. In the process of milling force calculation, a method for determining the instantaneous machining area in the blade surface finish machining and a algorithm for judging the micro-cutting element which participates in cutting process are proposed. Analyze the cutter deflection by using the theory of cantilever deformation, and finally calculate the surface machining error.3. Study the active error compensation method which reduces machining error by changing the tool paths, and give a detailed compensation step, namely determine the compensation amount based on the error amount of cutter location in the tool path. Modify the original NC program according to the compensation amount, and get the compensated NC program. On this basis, use MATLAB programming language, develop an active error compensation software. The software can calculate and analyze based on different machining parameters, modify the NC program according to the value of compensation.4. Carry out verification process by experiment. Respectively use the original NC code and the compensated NC code in the blade surface finish machining, then collect the points data of the blade surface with a coordinate measuring machine. Finally, analyze the surface differences by using IMAGEWARE, obtain the error color map and error data, verify the correctness of the proposed method and work.