Roller
hemming along a straight flange - pre-roller flanges the
upstanding flange at an 45 degree angle and final roller completes the
hemming process. Flange blank is held by deformable inner part at the
top and rigid part (anvil) at the bottom. Breakdown wrinkles
are visible
Mean
stress contour animation of the same flange in roller hemming process
viewed from another angle. Compressive stresses develop during movement
of the pre-roller and followed by tensile stresses developed during
movement of the final roller