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ROLLING - Coggle Diagram
ROLLING
defects
structural
surface
wavy edges
zipper cracks
edge cracks
alligatoring
strip spreading
higher width-to-thickness
decrease friction
larger rolls
edger mill
hot rolling
preferred grain shapes
lower stresses/forces/power
higher friction
recrystalization
mu = 0.2 -> 0,7
cond.
warm
: 2-20mm thick
cold
: to finish thickness
hot
: 20-50mm thick
cold rolling
work hardening increases strength
good surface finish and tolerances (no oxidation)
non-uniform residual stress distribution
ring rolling
thickness reduction as result of increased diameter
no waste
homogeneous grain structure
Mannesmann process
pair of cone-shaped rolls with
skewed axes
thanks frictional load, rod rotates and advances longitudinally
cyclic progressive compression
high tensile stresses in center that creates cavity
too high rolling forces
roll bending
no flat material (buckling)
roll flattening
poor tolerances
increased forces (larger contact area)
cluster mill
wide. 5000mm
thickness: 0,0025mm
residual stresses
small roll / large reduction
: tension in core
big roll / small reduction
: tension in skin
shape rolling
non-flat parts
usually in hot cond