Hey Guys,
I tried it: I took a line and recurve it or weld it and then with right click converted it into "Polyline segmentor" from the Bz toolbar of Fredo's plugin, and then changed the number of segment to 200 for example, but it didn't made it smoother, just divide it.
I did manage to make it smoother with the Subdivide and smooth plugin, but that action helped only one contour of the face and it is not a solution...
so- isn't there any way to import a spline from AutoCAD and not to regret it?