This document discusses various metal rolling processes including flat rolling, shape rolling, and seamless tubing and pipe production. Flat rolling involves feeding a metal strip between rolls to reduce thickness. Key factors that influence rolling include frictional forces, roll force, and power requirements. Hot rolling is used to initially break down ingots or continuously cast slabs, converting the cast structure to a wrought structure with finer grains and improved ductility. Shape rolling can produce items like bars, channels, and rails through specialized roll designs. Ring rolling expands thick rings into larger diameters while reducing thickness. Thread rolling forms straight or tapered threads on rods using thread-forming dies.

1. Meryanalinda, M.T

2. Proses Rolling Logam

3. ➢Bab ini membahas
✓ Flat rolling
✓ Shape rolling
✓ Pembuatan of seamless tubing & pipe
➢Apa itu proses Rolling? – process of reducing the thickness of a
long work piece
➢Plates – memiliki tebal lebih dari 6 mm
➢Sheets/lembaran – umumnya memiliki tebal kurang dari 6 mm

4. Flat Rolling Process

5. ▪ Metal strip masuk ke roll gap
▪ The strip is reduced in size by the metal rolls
▪ The velocity of the strip is increased the metal strip is reduced in size
▪ Factor2 yang mempengaruhi Rolling Process
▪ Frictional Forces
▪ Roll Force and Power Requirement

6. Friction Forces acting on strip forces
▪ Max Draft
▪ h0-hf = µ2R
Roll Force
▪ F= W0.L.Yavg
▪ L=̃ sqrt{R(ho-hf)}

7. FLAT-ROLLING PRACTICE
▪ Hot rolling
▪ The initial break down of an ingot
▪ Continuously cast slab
▪ Structure may be brittle
▪ Converts the cast structure to a wrought structure
▪ Finer grains
▪ Enhanced ductility
▪ Reduction in defects
▪ Continuous Casting
▪ Is replacing traditional methods
▪ Faster & better
Product of the first hot-rolling operation - Bloom or slab
▪ Square cross section of 150mm (6in) on one side
▪ Processed father by shape rolling
▪ I-beams
▪ Railroad rails

8. ▪ Billets – smaller than blooms and rolled into bars and rods
▪ Cold rolling
▪ carried out at room temperature
▪ Produces sheet and strip metal
▪ Better surface finish – less scale
▪ Pack rolling – when two or more layers of metal are rolled together
Changes in grain structure during hot-rolling

9. DEFECTS IN ROLLED PLATES & SHEETS
▪ Undesirable
▪ Degrade surface appearance
▪ Adversely affect the strength
▪ Sheet metal defects include:
▪ Scale, Rust, Scratches, Gouges, Pits, & Cracks
▪ May be caused by impurities and inclusions
▪ Wavy edges – result of roll bending
▪ Alligatoring – complex phenomenon

10. OTHER CHARACTERISTICS
▪ Residual stresses – produces:
▪ Compressive residual stresses on the surfaces
▪ Tensile stresses in the middle
▪ Tolerances
▪ Cold-rolled sheets: (+/- ) 0.1mm – 0.35mm
▪ Tolerances much greater for hot-rolled plates
▪ Surface roughness
▪ Cold rolling can produce a very fine finish
▪ Hot rolling & sand have the same range of surface
finish
▪ Gauge numbers – the thickness of a sheet is identified
by a gauge number

13. SHAPE-ROLLING OPERATIONS
▪ Various shapes can be produced by shape rolling
▪ Bars
▪ Channels
▪ I-beams
▪ Railroad rails
▪ Roll-pass design requires considerable experience
in order to avoid external and internal defects

15. RING ROLLING
▪ A thick ring is expanded into a large diameter ring
▪ The ring is placed between the two rolls
▪ One of which is driven
▪ The thickness is reduced by bringing the rolls together
▪ The ring shaped blank my be produced by:
▪ Cutting from plate
▪ Piercing
▪ Cutting from a thick walled pipe
Various shapes can be produced by shaped rolls
▪ Typical applications of ring rolling:
▪ Large rings for rockets
▪ Gearwheel rims
▪ Ball-bearing and roller-bearing races
▪ Can be carried out at room temperature
▪ Has short production time
▪ Close dimensional tolerances

16. RING ROLLING
(a) Schematic illustration of
Ring-rolling operation.
Thickness reduction
results in an increase in
the part diameter.
(b) Examples of cross-
sections that can be
formed by ring-rolling

17. THREAD ROLLING
▪ Cold-forming process
▪ Straight or tapered threads are formed on round rods by passing
the pipe though dies
▪ Typical products include
▪ Screws
▪ Bolts

18. THREAD ROLLING CON’T
▪ Threads are rolled in the soft condition
▪ Threads may then be heat treated, and subjected to final machining or
grinding
▪ Uncommon or special-purpose threads are machined

19. PRODUCTION OF SEAMLESS PIPE & TUBING
▪ Rotary tube piercing (Mannesmann process)
▪ Hot-working process
▪ Produces long thick-walled seamless pipe
▪ Carried out by using an arrangement of rotating rolls
▪ Tensile stresses develop at the center of the bar when it is subjected to compressive
forces

20. CONTINUOUS CASTING & INTEGRATED MILLS & MINIMILLS
▪ Continuous casting
▪ Advantages
▪ Highly automated
▪ Reduces product cost
▪ Companies are converting over to this type of casting

21. CONTINUOUS CASTING & INTEGRATED MILLS & MINIMILLS CON’T
Integrated Mills utilize everything from the production of hot metal to the
casting and rolling of the finished product
Minimills
▪ Scrap metal is melted
▪ Cast continuously
▪ Rolled directly into specific lines of products
▪ Each minimill produces one kind of rolled product
▪ Rod
▪ Bar
▪ Structural steel

23. TERIMA KASIH