Impact of cutting elements on forces and roughness of surface during turning hard steel X160 CrMo V12 with CBN tool

Abstract

Original scientific paper The goal of these researches is related to the analyses of the impact of elements of cutting mode on the change of cutting forces, quality of a machined surface and change of physical and mechanical properties of a surface layer of a CBN tool for turning of X160 CrMo V12 steel having a hardness of 60±2 HRC. The results of the analyses of tool surface wear indicate the presence of oxidation and changes of physical and mechanical properties in a tool surface layer. The evaluation clearly shows that a radial force (Fr) is dominant during the machining of this steel. The mathematical models of dependence of cutting force and a quality of machined surface were developed. It was ascertained that an oxidation of the tool surface, next to a contact zone toolcutting chip, leads to the increase of their hardness and reduction of their strength, and it finally leads to the emergence of micro-wear of a cutting knife and rapid tool wear. Keywords: CBN (corundum and boron-nitride); force; roughness; turning; wear Utjecaj parametara rezanja na sile i hrapavost površine pri tokarenju kaljenog čelika X160 CrMo V12 alatom od CBNIzvorni znanstveni članak Cilj ovih istraživanja se odnosi na istraživanje uticaja elemenata režima rezanja na promenu sila rezanja, kvaliteta obrađene površine i promene fizičko-mehaničkih svojstava u površinskom sloju alata od CBN pri struganju čelika X160 CrMo V12, tvrdoće 60±2 HRC. Rezultati istraživanja habanja površine alata ukazuju na prisustvo procesa oksidacije i promene fizičko-mehaničkih svojstava u površinskom sloju alata. Evaluacija sile jasno pokazuje da je radijalna sila (Fr) dominantna pri obradi ovog čelika. Razvijeni su matematički modeli zavisnosti sila rezanja i kvaliteta obrađene površine. Utvrđeno je da oksidacija površine alata, neposredno uz kontaktnu zonu alat-strugotina, dovodi do povećanja njihove tvrdoće i smanjenja čvrstoće, što u krajnjoj meri dovodi do pojave mikrokrzanja reznog sečiva a time i ubrzanog habanja alata.

Technological Heredity of the Turning Process

“…Many factors influence the surface quality of longitudinally turned workpieces. The most important ones include: technological parameters of the machining process, stereometry of the cutting edge, vibrations resulting from the machining process, machinability of the workpiece, built up edge, elastic and plastic deformation of the tool and workpiece in the machining zone [2][3][4]. On the other hand, the dominant factors influencing the quality of the turned surface are the complex motion of the cutting tool and workpiece expressed by the feed rate fn and the cutting speed v c .…”

Optimization Parameters of Milling Process of Mould Material for Decreasing Machining Power and Surface Roughness Criteria

“…Recently, investigators solved the trade-off among multiresponses regarding surface quality, energy consumed, and processing efficiency. The technological responses included are cutting energy [11], tool wear [12], cutting force [13][14][15][16], residual stress [17], material removal rate [18], and machining time [19]. Additionally, the surface geometry [20], chip formation [21,22], micro-hardness, and microstructure [23] were considered as important technical outputs.…”