Research Of Workpiece Temperature In Orthogonal Turn-milling Compound Machining Hard Materials

Orthogonal turn-mill compound machining is one of the most important advancedmanufacturing technologies of metal cutting. The characteristics of high strength andhardness give hard metal material components both excellent performance and propertiesof difficult to machine which is aggravated for extremely low thermal conductivity.Machined surface of workpiece might be burned and tool wears dramatically are commonphenomena as the cutting force and heat is extremely high when hard metal materials cutat high speed.This paper carried out a study of prediction of workpiece temperature field inorthogonal turn-milling compound machining hard metal materials. First, kinematics oforthogonal turn-milling and geometry of the cutting process has been analyzed. Then, themilling tool and cutting time were discretized into several slices and tiny periods of thesame size respectively. Tooth infinitesimal cutting process was analyzed with the way ofobliquely cutting to solve the shear surface heat flux density. The formula calculatingtemperature rise on workpiece was derived with a finite instantaneous mobile plane heatsource model for an arbitrary infinitesimal cutter. Total influence on workpiecetemperature of the whole milling tool was an integration of temperature rise ofinfinitesimal cutters on time and axis of milling tool.A seven factors and three levels orthogonal cutting experiment indicating workpiecetemperature model was carried out considering several factors that have great effects onorthogonal turn-mill workpiece temperature to test the indication of the temperature model.Instantaneous temperature rise measured with the experiment matched well with thoseestimated with the model established in this paper. Workpiece temperature rise waspredicted with the temperature model for factors of cutter rotational speed, ratio of cutterand workpiece speed and workpiece diameter. The degrees of effects these factors have onworkpiece temperature rise was analyzed with statistical analysis of range and variance ofthe results of cutting experiments and predictions.A SHPB（Split Hopkinson Pressure Bar）and quasi-static uniaxial tensile test wereexecuted for300M ultra high strength steel, a kind of hard metal material which is widely used in aircraft landing gear. A three-dimensional solid model of milling tool wasestablished for the cutting simulation with the professional metal cutting finite elementsimulation software AdvantEdge FEM with the JC constitutive model from SHPB andquasi-static uniaxial tensile experiments.The regular of workpiece temperature changing with process parameters whenorthogonal turn-milling hard materials from cutting experiments and analytical model andcutting finite element simulation is effective for guidance of process parameters selectionto make sure machine efficiently with high quality.