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Modeling and Simulation of Chip Formation in High Speed Cutting

Introduction

 

hscvortrag_Page_02_Image_0001       hscvortrag_Page_02_Image_0002
Ck45, vc= 150 m/min
Homogeneous deformation due to homogenising effect of heat flux.
      Ck45, vc= 800 m/min
Segmentation of chip as an effect of material instability caused by adiabatic heating.

The effect of localized adiabatic shear bands can be identified as the main mechanism of deformation during the process of High Speed Cutting (HSC). Unlike the case of cutting with low cutting speeds where heat flux homogenizes and stabilizes the whole process of deformation, the heat produced by plastic deformation stays inside the deformation zone. The concentrated encreasing of temperature in a localized area leads to material softening and finally initializes a material instability in form of a localized adiabatic shear band. The softening of material is the explanation for the effect of decreasing cutting speed.

 



FE-model

 

fe_model

The FE-Model consists of the cutting tool, modelled as 2-dimensional analytical-rigid-body and the workpiece that contains the thermo-viscoplastic ansatz.

 



Shear bands and mesh dependence

 

fe_shearbands       fe_shearbands_meshdependence



Results

 

fe_results01

The orientation of the mesh can be used consciously to force the shear band in the direction observed experimentally. In the same way the thickness of material instabiliy can be adjusted by characteristic element length. The model allows to simulate the shape of the chip and the resulting cutting forces with a minimum of numerical costs. Although the implementation of a remeshing algorithm in combination with a non-local material ansatz is required to give the model more flexibility and physical backround. Beyond, the implementation of a failure model to model the breakup and the cutting surface is part of work in progress.

 



Contact/Author information

 

Dr.-Ing. Christian Hortig