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The Evaluation of Cutting-Force Coefficients Using Surface Error Measurements Journal of Materials Processing Technology 196 (2008) 42-51 Mariana Dotcheva, Huw Millward, Alan Lewis Presenter: Andrew Gerla 07 October 2009. Purpose.
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The Evaluation of Cutting-Force Coefficients Using Surface Error Measurements Journal of Materials Processing Technology 196 (2008) 42-51 Mariana Dotcheva, Huw Millward, Alan Lewis Presenter: Andrew Gerla 07 October 2009
Purpose To provide a new approach for the determination of cutting forces.
Cutting Force Affects... • Required machine power rating • Tool wear • Tolerances • Surface finish • Required lubrication and cooling • Economy of prototyping and small batches
Old Methods • Use mechanistic models with empirical coefficients • Require expensive instrumentation to gather empirical data • Require skilled technicians to record and process data • Applicable only to the conditions under which test was performed • Not easily implemented for prototyping or small batch work
The Proposed Method • Cutting force is proportional to tool deflection • Tool deflection is related to surface finish • Empirical relationship may apply to operations with different cutting conditions Find equations like these: • Tangential force KT(tc) = Ct1(tc)−kt1 • Radial force KR(tc) = Ct2(tc)−kt2
Method • Discretize cutting tool by: • Flute • Angle of rotation • Discs normal to axis of rotation
Analytical Models Cutting Forces: FX(θ(i, k, j)) = KT(EX1 + KREX2) FZ(θ(i, k, j)) = KT(EZ1 + KREZ2) FY(θ(i, k, j)) = KT(EY1 + KREY2)
Analytical Models Tool Deflection: δ(h) = δs + θs(h) + δt(h)
Experimental ProcedureCutting Test • Cut two strips with the same cutting conditions • Vary axial depth by ∆a • Calculate difference in surface finish • Difference in surface finish mainly due to additional forces from elemental disc ∆a • 12 different feed rates
Experimental ProcedureCutting Test • End milling operation • HSS 3-flute 16mm cutter • Aluminum alloy 6082 • Down-milling (climb-milling) • Radial depth 3 mm, axial depths 8 and 9mm • ∆a = 1mm
Experimental ProcedureData Acquisition • CNC operated profilometer • Maximum error 3.2% • Straight measuring tool paths, 0.1mm increment
Results MATLAB curve fit:
Conclusions • Analytical model accurately predicts experimental data in similar cutting conditions • Uncut chip thickness can be calculated • Study needs more verification of accuracy for different cutting conditions • Different materials require different coefficients