1. Rolling
Process of reducing the thickness or changing the cross-section area of a long work piece by compressive forces.

2. accounts for about 90% of all metals produced by metalworking processes.
forging operations produce discrete parts, where rolling operations produce continuous products.
Engr 241

3. Plate
> ¼” thick
Ship hulls
Bridges
Boilers
Engr 241

4. Sheet
< ¼” thick
Auto bodies
Containers
Appliances
Engr 241

5. Aluminum foil candy wrapper = .0003”
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6. Gage numbers
Smaller # = thicker sheet
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7. Ingot
Initial form for rolling if not continuous
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8. Rolling
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9. Rolling Rolls
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10. Rolled Texture
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11. Unrolling and Straightening of Rolls (Maytag)
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12. Roll Loading
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13. Rolling Process Terminology (raw material)
Bloom: square cross section of at least 6" on the side. (sheets)
Billets: square cross section, smaller than bloom. (rod, pipe)
Slab: rectangular in shape, rolled into plates and sheet. (rails, I-beams)
Engr 241

14. Rolling Mills
Two-high
primary roughing (cogging mills).
Engr 241

15. Three-high primary roughing (reversing mill).
Direction reversed after each pass
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16. Four High & Cluster
principal - (small diameter) rolls lower the roll forces and power requirements, but must be supported in order to reduce deflection.
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17. Rolling Mills
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18. Rolling Mills Tandem Rolling
strip is rolled continuously through a number of strands (set of rolls with its own separate housing and controls) to smaller gauges with each pass.
Group of Strands = train
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19. Roll Deflections forces cause roll deflection and roll flattening.
Make roll dia larger at center
Subject rolls to bending – apply moments at bearings
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20. Roll Deflections Forces can be reduced by: reducing friction.
reducing contact area.
smaller reductions per pass.
rolling at elevated temperatures to reduce strength of material.
Engr 241

21. Roll Materials Cast iron Cast steel Forged steel Aluminum Alloys
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22. Rolling Processes Flat-rolling
hot or cold work (slabs, blooms, billets, or sheet metal).
3000 °F for refractory alloys.
2300 °F for alloy steels.
850 °F for aluminum alloys.
Pack Rolling: two or more layers of metal rolled together (Al foil example)
Engr 241

23. Flat-rolling (Cont.) Defects
wavy edges – roll bends where strip is thinner along it’s edges
Cracks – poor material ductility at the rolling temp
alligatoring – non uniform deformation during rolling or defects in original billet
Engr 241

24. Rolling Processes
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25. Shape Rolling structural shapes (I-beam, rails, etc.)
requires specially designed rolls
Engr 241

26. Ring Rolling
ring (which is the part) placed between two rolls, to increase diameter.
large rings for rockets, gearwheel rims, ball bearing and roller- bearing races, flanges, reinforcing rings for pipes, etc.
Engr 241

27. Thread rolling
cold-forming process where threads are formed on round rods by use of flat reciprocating dies which pass the part between them.
no material loss.
no cutting through grain line flow improves strength.
Engr 241

28. Rotary Tube Piercing
hot working process for making long, thick walled seamless tubing/pipe.
round bar subjected to radial compressive forces causing tensile stresses toward the center of the bar.
cavity forms from cyclic compressive stresses.
Engr 241

29. Continuous casting Highly automated and productive Spray casting
Molten metal sprayed over a rotating mandrel to produce seamless tubing and pipe
Engr 241

30. Minimills
Scrap – continuously cast and rolled into specific line of products located locally to scrap producer
Engr 241