5. Conclusion
A method of reducing residual stress generated by laser cutting
was proposed. The FEM analysis and experiment examinations
verified the validity of this method. Results were as follows.
1. The proposed method, which presses the edge of sheet metal,
was drastically effective for levelling the warp.
2. The optimum pressure Po is proportional to 1% proof stress 1%,
and the proportion ratio Po/1%, was 110–130% regardless of the
maximum residual stress and mechanical properties.
3. The proposed method is ideal as it has a stable levelling effect
on the residual stress regardless of the intensity of the residual
stress.
Although the proposed method is effective for the presented
geometry, there are some works to be carried out in the future as
follows:
1. Various geometrical parameters
Even if flange length changes, the optimum pushing pressure
may not be affected because the residual stress should be levelled
under the optimum condition regardless of flange length.
However, this should be verified.
2. Thickness
The optimum condition should be examined in terms of thickness.
If the sheet metal/plate is too thick, the thickness might
affect the thermal history during laser cutting, leading to change
of residual stress and its distribution in thickness direction. The
thickness may also affect the deformation of sheet-metal/plate
in light press.
3. Material
If the material has a property of significant phase change, or
long elastic range as in titanium, the optimum condition may be
affected. Further investigation should be conducted for various
materials.