40crNiMo Steel Hard Cutting Process And Surface Morphology Research

Manufacturing has been the main factor that drives economic growth, and form thebeginning to end manufacturing is looking for a kind of energy-saving,environmental-protection, economic and efficient mode of production processingparts or to improve the existing production process. Many products working in badconditions have higher requirements on the workpiece surface hardness and resistance,such as gears, bearings and TBM machinery knives, they are all made of hardenedsteel. The traditional processing craft route for hardened steel is: coarse car–hardened–fine grinding. The emergence of PCBN cutting tools has brought a newway of precise machining, hard cutting, which can be directly carried precise turningprocessing on the hardening workpiece, thus no or only a small amount of grinding isneeded.This thesis reviews the current situation of the development of both at home andabroad of hard cutting hardened steels, and determines the geometry parameters ofcutting tool and the three cutting elements, and formulated the cutting plan. Thisthesis establishes the finite element simulation of hard cutting2d and3d modelthrough appropriately simplified on the basis of the actual model, and uses the seriesof Deform software to simulate the hard cutting process under different conditions.Studied and analyzed the three cutting forces changing with the three elements ofcutting, and compared with the experimental results, analysis of variance to get themost significant factors that influences the cutting forces. On the basis of thethree-dimensional cutting, using Deform2D simulated the tow-dimensional cuttingprocess, simulating the formation mechanism of serrated chip of the hard cuttinghardened40CrNiMo steel, and compared the simulation chip morphology andexperimental chip morphology. As the processed surface morphology directly affectthe fatigue performance of a workpiece, in this thesis, observing the processed surfacemorphology, and measuring the surface roughness of the workpiece, observing themicrostructure of the surface layer. Through the simulation analysis and experimental research, this thesis gets theinfluence of the three elements of cutting on cutting forces, using the least squares fitsout the experience formula of cutting forces. Through variance analysis gets theinfluence ofa pon the three cutting forces is highly significant, the influence of fon the three cutting forces is not significant. By analyzing the surface morphology ofthe workpiece, workpiece surface roughnessR acan be up to the level of thegrinding, workpiece surface roughnessR zis below the grinding. Under thiscondition of cutting, the surface of the workpiece is fine grain martensite structure,high hardness and good abrasion resistance.