Influence of technological factors of blade processing on the forming of the defect layer

Abstract

Abstract. Identified the interrelationships between the depth of the surface layer with modified physicalmechanical properties (defective or work-hardened or fill hard layer), the parameters of cutting process, and the properties of materials of tool and workpiece. Justified the necessity of research the processes of formation the properties of the machined surface from the standpoint of the thermo-physics of the cutting process.The formation of subsurface deformation is an attribute of the wedge cutting process. The subsurface deformation significantly affects on the resistance to corrosion and other performance properties of the product. A number of researchers [2,3,5] notes that in the surface layer, in addition to changes in physical and mechanical characteristics of the material, such as microhardness, strength and ductility may also change in the crystal structure. As a rule, the condition of the subsurface deformation is evaluated by two basic indicators: the depth and degree of hardening. The degree of hardening is defined [2] as the change in the microhardness of the surface layer in relation to the original material. In the studies of A. D. Makarov, L. G. Odintsova and other authors [2,3,12] identified the main reasons for the formation of the layer with modified physical and mechanical properties -the combined effects of cutting forces and increased temperature induced during a machining. At research by N. V. Talantov [4] and his students proved that the formation of the deformed layer is greatly influenced by the friction at the rake surface and rear surface of the tool, forces and temperature processes in the primary shear zone, temperature and diffusion processes of the "blank-tool" and "chip-tool". All of these factors are the result of the influence of independent technological conditions of a metal cutting process: physical-mechanical properties of materials of the tool and the workpiece, the method of forming, cutting conditions (cutting speed, depth of cut, feed) and the geometric parameters of the cutting wedge.

Formation of the Properties of the Surface Layer during Multi-Stage Milling

“…Previously in [8,11,12], we analyzed the effect of machining conditions on the accuracy and geometrical parameters of the microprofile of the machined surface during multi-stage milling. The estimations were done by using the degree of accuracy IT to detect the accuracy of machining and by using the arithmetic average deviation of the microprofile height Ra to detect the surface microgeometry.…”

“…The estimations were done by using the degree of accuracy IT to detect the accuracy of machining and by using the arithmetic average deviation of the microprofile height Ra to detect the surface microgeometry. According to the analysis of our own experimentally obtained results and the results of other studies [1,2,5,7], probability tables of accuracy [8,9,10] were built for the given machining parameters. Four machining stages significantly different in terms of achievable accuracy were defined: roughing, semi-finishing, finishing and fine finishing.…”