Trinity College Dublin MODELLING THERMAL EFFECTS IN MACHINING BY FINITE ELEMENT METHODS Andrea Bareggi (presenter) Andrew Torrance Garret O’Donnell Department of Mechanical and Manufacturing Engineering The University of.
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Trinity College Dublin MODELLING THERMAL EFFECTS IN MACHINING BY FINITE ELEMENT METHODS Andrea Bareggi (presenter) Andrew Torrance Garret O’Donnell Department of Mechanical and Manufacturing Engineering The University of Dublin Trinity College IMC 2007 Authors Trinity College Dublin Introduction FE modelling for metal cutting • Cutting forces, plastic deformation (shear angles and chip thickness) • Temperature in the workpiece, chip and tool IMC 2007 • Stress, strain, strain rate predictions • Temperature distribution in the primary, secondary and tertiary sub-cutting zones Trinity College Dublin Commercial packages IMC 2007 ABAQUS • Manual design of geometry, meshing and boundary condition setting • No material library, but materials can be defined in detail • Partial support in adaptive remeshing • Good control of the solver Trinity College Dublin ADVANTEDGE • Very efficient interface to rapidly configure a model, tool library is provided • Extensive material library • Uses adaptive remeshing, but controls can not be modified • Not suitable for customising control functions IMC 2007 Commercial packages Trinity College Dublin DEFORM 3D • Built in “wizard” for machining • Good material library and comprehensive material editor • Uses adaptive remeshing, good control of meshing parameters • The user can chose the solver and minimal control is permitted IMC 2007 Commercial packages Trinity College Dublin Problem formulation Incremental Lagrangian formulation Implicit integration method Solver with sparse matrix Direct method IMC 2007 • • • • Trinity College Dublin Problem formulation • • • • workpiece IMC 2007 Cutting speed: 270m/min Feed: 0.06mm/rev Depth of cut: 0.5mm Effective rake angle = 0° nose radius = 0.2mm • Cooling method: air jet • AISI 1020 steel workpiece,1.5 mm of length, plastic • WC insert with reduced insert heat capacity, rigid Trinity College Dublin Thermal boundary conditions • No cooling, natural convection, h=20 W/m²/K • Air jet, overhead position, h=2000 W/m²/K • Air jet, interface position, h=2000 W/m²/K overhead interface Interface nozzle dir. IMC 2007 Overhead nozzle dir. Trinity College Dublin Results Chip temperature (416°C) IMC 2007 • Steady state condition: workpiece, interface, insert • Temperature prediction: workpiece, chip and interface Trinity College Dublin feed=0.06mm/rev depth=0.5mm speed=270m/min Max workpiece temp. (°C) Interface temp. (°C) Chip temp. (°C) Cutting Force (N) Dry cutting 737 721 710 627 416 389 93 92 727 648 408 95 Air jet cooling, overhead Air jet cooling, interface • Reduction of interface temperature • Best cooling in overhead position • No influence on the cutting force IMC 2007 Results Trinity College Dublin Results Temp (°C) B=88 C=156 D=225 E=293 F=361 G=429 H=498 I=566 J=634 K=702 IMC 2007 • Prediction of gradient temperature within the insert • Developing of experimental techniques for investigating temperature A=20 Trinity College Dublin Conclusion IMC 2007 • Results consistency: analytical results, ADVANTEDGE simulations, preliminary temperature measurements • Finite Elements: cost saving in experimental work, process insight in cooling and lubricating method • 3D modelling techniques under development, in particular with cooling Trinity College Dublin Further research IMC 2007 • Refinement of the model, estimation of the heat transfer coefficients, improved approach to jet modelling • Simulation with different workpiece materials and cutting conditions • Experimental validation, currently ongoing Trinity College Dublin •N.A. Abukhshim, P.T. Mativenga, M.A. Sheikh, Heat generation and temperature prediction in metal cutting: A review and implications for high speed machining, International Journal of Machine Tools & Manufacture 46 (2006) 782–800 •J.D. Gardner, A.Vijayaraghavan, D.A. Dornfeld, Comparative Study of Finite Element Simulation Software, eScholarship Repository, University of California, Copyright c 2005 by the authors •T. O’Donovan, Fluid flow and heat transfer of an impinging air jet, Phd. Thesis, Mechanical & Manufacturing Engineering, Trinity College Dublin, 2005 •D. Umbrello, L. Filice, S. Rizzuti, F. Micari, On the evaluation of the global heat transfer coefficient in cutting, International Journal of Machine Tools & Manufacture 47 (2007) 1738–1743 IMC 2007 Literature & Acknowledgements Trinity College Dublin Literature & Acknowledgements Questions? Christian E. Fischer, Ph.D., PE, (Scientific Forming Technologies Corporation, Columbus, Ohio, USA) IMC 2007 Acknowledgements