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Contribution à l'optimisation du procédé d'usinage assisté laser

Abstract : Laser assisted machining (LAM) is a machining process that consists of heating the workpiece via a laser beam, upstream of the cutting tool. The mechanical properties of the workpiece, in the locally heated zone, are greatly reduced, which translates as an increased machinability. This work investigates the influence of laser assistance on the machiniability and the surface integrity of several materials: 42CrMo4 steel, 100Cr6 steel (heat treated to 57 HRc), and titanium alloy Ti6Al4V. The measurement of the cutting force is used to quantify the increase in machinability of the materials, as a function of the laser power and the cutting parameters. In certain configurations, the cutting force is decreased by 50 % for 100Cr6 and up to 40 % for the Ti6Al4V. The surface roughness is relatively insensitive to the laser power. However, the residual stresses tend towards positive values (tension) with the increase of the surface temperature. This modification of the residual stresses causes, for example, a decrease of 30MPa in the push-pull fatigue limit of the titanium alloy. At the same time the fatigue limit changes with the heat treatment caused by the laser at the cut surface during LAM. For the titanium alloy, the laser heat treatment creates a needle-shaped microstructure which is catastrophic in terms of fatigue. On the other hand, for the 100Cr6 steel, a thin layer of martensite(with strong compressive residual stresses) is created on the surface which increases the fatigue limit by approximately 70MPa. Numerical simulations of LAM and conventional machining have been undertaken in order to understand the role of the laser heat input on chip formation. The results show a decrease in the cutting force as laser power is increased. This is in agreement with the experimental work. The results obtained permit the optimization of the cutting parameters and to determine the mechanical and thermal loads on the cutting tool.
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https://pastel.archives-ouvertes.fr/pastel-00002127
Contributor : Ecole Arts Et Métiers Paristech <>
Submitted on : Thursday, February 1, 2007 - 8:00:00 AM
Last modification on : Friday, July 17, 2020 - 2:58:25 PM
Long-term archiving on: : Monday, October 22, 2012 - 4:50:16 PM

Identifiers

  • HAL Id : pastel-00002127, version 1

Citation

Guenaël Germain. Contribution à l'optimisation du procédé d'usinage assisté laser. Sciences de l'ingénieur [physics]. Arts et Métiers ParisTech, 2006. Français. ⟨NNT : 2006ENAM0051⟩. ⟨pastel-00002127⟩

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