Study On Prediction Of Surface Roughness In NC Machining

Surface roughness is not only a parameter which controlling surface quality but a parameter to inspect machining process. To seek optimal machining parameters so as to control machined surface roughness, more and more researchers hope to model more precise surface roughness prediction models, on the basis of fewer experiments, don't be controlled by traditionally experience expressions or refer to guides/handbooks and achieved optimum machining.There are many factors which influenced surface roughness in actual machining process. They are stochastic non-geometry factors and geometry factors in some rules, besides cutting mode, workpiece material, cutter material and machining parameters. Non-geometry factors influenced surface roughness greatly during conventional milling operation, but influence of geometry factors more and more important during middle or high speed machining.Based on lots of literatures which related with surface roughness prediction, this paper mainly study the key techniques including influence factors and influence rules of machined surface roughness, generating mechanism of surface roughness, as well as prediction of machined surface roughness on multi-axis NC machining.For influence factors and rules of machined surface roughness, we studied on the influence factors of machined surface roughness such as scallop-height, path interval, feed rate and optimum tool path.For mechanism of the surface roughness generation, based on differential geometry theory, we analyzed the surface micro-geometry topology swept by edges of ball-end mill according to rotate movement and translate movement on optimal tool path, and achieved the influence expressions of edge locus decided by cutting parameters(such as feed rate, path interval and inclination angle of ball end mill).For surface roughness prediction of complicated and sculptured surfaces bymulti-axis NC machining, based on Ridge Prediction Method, we studied on final topology of machined surface and predicted the three-dimensional grid plots of scallop-height topology in MATLAB6.1, Visual C++ 6.0 and OpenGL environment.We validated the studied method and theory for prediction of surface roughness by simulation of final scallop-height topology and comparison between the predicted results and the values measured by actual machining experiments.