Research On Cutting Characteristics Of PVD Coated Tools When Cutting Sandstone In High Speed

With the advantages of less pollution,non-radiative,non-reflective,non-weathering,invariant color,heat absorption,insulation and anti-skidding,the natural sandstone which has been blooming its unique light since the ancient architectures of hundreds of years ago to the modern architectural field.Because of the increasing types of building materials,the application of natural stone is gradually moving into people’s field of vision.However,the high-speed cutting technology can not fit for sandstone,due to its special structural characteristics.So,how to better use high-speed cutting technology in the processing of sandstone has already become a problem to be solved urgently.In this thesis,high-speed machining center and PVD diamond coated-tools are used in the process of cutting natural sandstone.The influence of cutting parameters and cutting conditions on the cutting-force,surface-roughness,surface-topography and wear-area of tool has been researched through the experimental data.In order to lay a certain theoretical and practical basis on high-speed cutting technology,and it can be better applied to the processing of natural sandstone in the future.The orthogonal-test results of cutting-force showed that with the increase of feed-rate,the cutting-force increased slowly and Fx was more prominent than Fx and Fz.With the increase of cutting-depth,the cutting-force rose significantly.With the increase of the spindle speed,the cutting-force reduced gradually,and the effect on the Fx and Fy was significantly higher than that of Fz.The surface-roughness of the machined sandstone was measured by the roughness tester.The results showed that the surface-roughness of the sandstone resulted in decrease with the increase of the cutting-speed,which showed that cutting-speed was the key element in improving the surface quality of sandstone.With the increase of feed-rate,the surface-roughness rose smoothly.With the increase of cutting-depth,the surface-roughness resulted in a marked rising.The phenomenon showed that the cutting-depth was the key factor in the deterioration of surface quality.With the Scanning-Electron-Microscope,the surface of sandstone under different cutting conditions had been observed,and the results of wet-milling could get the better surface-morphology and the probability of generating surface defects was smaller in the process.In addition,the wet-milling process got smaller chips than the dry-milling.Therefore,the application of cooling-fluid played a key role in improving the surface quality of the sandstone in the process of milling sandstone.The wear-area of the tool was calculated by the grid-method.The results showed that the wear-area of the tool surface was significantly lower with the main-shaft speed becoming faster.This phenomenon showed that the increase of the spindle-speed could improve the wear-form of the tool surface.But with the increase of cutting-depth,the trend of the increase of the cutting-depth was linear,the increase of cutting-depth directly deteriorated the integrity of the coating on the surface of the tool.At the same time,the surface wear-morphology of the cutting tool was analyzed under amplification observation.The results showed that the main reason of tool surface invalid was the rear-face furrow,chipping and the phenomenon of coating peeled.In addition,the presence of product-clipping was found in the front face of the tool.Based on the test data,the empirical-formula models of the cutting-force,roughness,tool-surface wear-area and the main-shaft speed,feed-rate and cutting-depth were established respectively.After the dual validation of the significance test and the experimental test,the error was within the allowable range,so the formula was reliable and practical,it could be applied to the actual needs.