Proceedings of SerbiaTrib '13

f M3 F ⋅ R= ⋅ , (6)4 N ⋅ rwhere R – radius of the disc, [m]; r – radius of theimpress on the sample, [m]; N – normal force, [H]; F –peripheral force on the disc, [H].quality and accuracy levels at the stage ofmachining and takes into consideration thetribological properties of coated tools, has beendeveloped. The methodology can estimatetechnological conditions of turning and solve aninverse task – it can estimate roughness, residualstress and strain hardening. The algorithm forcalculation of required technological conditions ofturning was implemented in the software (figure 7).Opportunity to choose oredit a function of frictionFig. 5. The flow chart of one-ball adhesiometer; 1 –samples of the work material; 2 – indenter of the toolmaterial; N – normal force, which impress the indenter[H]; F – peripheral force, which roll the disc, [H].Figure 6 shows the friction coefficient, whichwas determined for different temperatures andcombinations of work materials – coated indenter(pin).Figure 6. The influence of the temperature on afriction coefficient; work material – heat-resistant alloyEI437; tool material – carbide material H10F;nanostructured coatings of indentor: H10F (withoutcover); (Ti;Si)N; (Ti;Si;Al)N;TiB 2 ; Al 2 O 3.Thus if the magnitude of the criterion B 1 ofcover 1 and the functions of friction f M = f(θ) ofcover 1 and 2 like the dependence of frictioncoefficient on the temperature θ are known, themagnitude of a unknown criterion B 2 of cover 2can be approximately estimated by means ofcorrecting coefficient:cov er1Mcov er2Mfk = (7)fcov er1 cov er2where f M , f M – adhesion componentof the friction coefficient of work material withcover 1 and 2.On the base of obtained results of experimentsthe methodology for calculation of technologicalconditions of turning, which provides requiredFig. 7. The software for calculation of requiredtechnological conditions of turning.In order to check the obtained mathematicalmodels, the comparison of the experimental andcalculated data was performed. The investigation ofthe parameters of surface layer has been performedon the machined parts “ring”. The conditions ofturning of the parts “ring”: work material –stainless steel EK26; tool material – carbidematerial VK6R; tools geometry: φ = φ 1 = 45°, γ =8°; α = 7°, r = 1,2 mm; cutting rate: t = 0,75 mm; S= 0,2 mm/rev; nanostructured coatings of tool:(Ti;Si)N; (Ti;Si;Al)N.The results of experiments (Table 3) have beenclearly shown, that coated tool reduces themagnitude of the roughness, residual stress andstrain hardening in according with the magnitude offriction coefficient. The calculation of theparameters of the surface layer was performed bymeans of mathematical models presented in [2] andsoftware. The parameters of the roughness Ra andRz reduce on the average 5 %, therefore the maincause leading to the formation of the roughness aretools geometry, feed rate, vibration and so on, butnot the cover of tool. The strain hardening reduceson 20 % as compared with uncoated tool.In order to check our obtain data we havecompared the experimental and calculateddistribution diagrams of tangential residual stress.The using of coated tool leads to the considerablereduces of adverse tensile residual stresses.The distribution diagrams of the tangentialresidual stress are shown on a Figure 8.202 13 th International Conference on Tribology – Serbiatrib’13