Proceedings of SerbiaTrib '13

Fig. 3. The comparison the criterion В andtechnological conditions of operation; Work material –the stainless steel EK26, tool – TT7K12, coating – ZrB 2.It is clearly shown, that in the time of increasingof cutting speed v the criterion В increases too. It isthe reason for increasing of an angle of shear planeβ 1 . The angle of shear plane β 1 increases, becausethe materials ultimate stress σ В reduces by reason ofincreasing of rate of deformation and temperaturein the cutting area.On the base of experimental research theinfluence of different technological conditions onthe criterion В has been obtained. The quantity ofshear plane β 1 of coated tool increasesapproximately on 5-10 %. But experimentalequations are limited by technological conditions ofexperiments and couldn’t be used for otherconditions or other covers of tool. Therefore themethodology for estimating of a criterion B forother covers of tool has been developed. Thismethodology is based on the taking intoconsideration adhesive component of the frictioncoefficient f M of coated tool.For determination of the friction coefficient twoapproaches were used. According to the firstapproach, friction coefficient μ F was determined asa ratio of a tangential force to a normal force ofcutting:F FtanPy + Pх Ру ⋅ cosϕ+ Px ⋅ cos(90 − ϕ)µ = = =,(3)N РzPzwhere μ F – friction coefficient; Py, Px, Pz – componentsof a cutting force, [Н]; F tan – tangential force to a cutterface, [Н]; N – normal force to the cutter face, [Н]; Py –radial component of a cutting force, [Н]; Px – axialcomponent of a cutting force, [Н].On the figure 4 the dependence of criterion Band friction coefficient μ F on a dimensionlessv ⋅ a1complex Pe = , which defines theatechnological conditions of operation, has beenshown.The comparison of curves on the figure 4permits to create the proportion:В21Fµ ⋅ В1= (4)µF2The magnitude of unknown criterion B 2 can beapproximately estimated if the magnitudes ofF Fcriterion B 1 and friction coefficients µ1, µ2whichcorrespond to the tools with different coatings, areknown. But the determination of the frictioncoefficient μ F according to the first approachdoesn’t take into consideration the temperature inthe cutting area.The second approach has ‘not this shortcoming.According to the second approach fordetermination of the friction coefficient theadhesiometer was used (figure 5). It is known, thatthe friction coefficient:f = f D + f M , (5)where f D – deformation component of the frictioncoefficient; f М – adhesion (molecular) component of thefriction coefficient:Fig. 4. The dependence of criterion B and friction coefficient μ F on a dimensionless complex Pe; work material –Stainless steel EK26; tool material – carbide material VK6R; nanostructured coatings of tool: VK6R (withoutcover); (Ti;Si)N; (Ti;Si;Al)N; TiB 2 ; Al 2 O 313 th International Conference on Tribology – Serbiatrib’13 201