International Conference on TIM, 2012, Nepal
ROLLING INDUSTRY
Anand Nepal
ED
Kathmandu Steel Pvt. Ltd.
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International Conference on TIM, 2012, Nepal
Over View of Presentation
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Rolling
Mills
Process & Profiles
Development & Innovations
Nepalese Scenario
Conclusion
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International Conference on TIM, 2012, Nepal
Rolling
• Metal forming process in which metal stock is
passed in between pair of rolls.
– Hot Rolling : Temperature above re-crystallization
– Cold Rolling : Temperature below re-crystallization
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International Conference on TIM, 2012, Nepal
Hot Rolling
-Metal working process that occurs above the recrystallization temperature of the materials.
-This prevent from work hardening.
-Large piece of metal, Blooms, Billets, Slabs .
-Continuous casting operation fed directly.
-Must Heated, if room temperature materials.
-Temperature should be monitored.
-Form oxide at surface of metal during process.
-Used to produce- sheet metal, simple cross sections
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International Conference on TIM, 2012, Nepal
Cold Rolling
-Occurs with the metal below its re-crystallization
temperature (room temperature).
-Increase the strength.
-Improve the surface finish and holds tighter tolerances.
-Sheets, strips, bar, and rods: but they are smaller compared
with hot rolled products. – sheets and strips different
conditions- full hard, half hard, quarter hard and skin
rolled.
-Smaller size reduction as compared to hot rolled.
-Require different operation: sizing, breakdown, semiroughing, semi finishing and finishing.
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International Conference on TIM, 2012, Nepal
Over View of Presentation
•
•
•
•
•
•
Rolling
Mills
Process & Profiles
Development & Innovations
Nepalese Scenario
Conclusion
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International Conference on TIM, 2012, Nepal
Mills
-By Hot or Cold rolling and form or shaped in different
products using machines.
-Material are feed and output from mill is coiled or in
different straight length.
-Designed in different types of configurations:
a)Two High, b)Three High, c)Four High,
d)Six High and e & f) Cluster. (fig.)
-Two high most basic & non reversing.
-Three high rotate in one direction- fed through and returned
back. Work piece to be lifted.
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International Conference on TIM, 2012, Nepal
-Minimize the roll diameter four high or cluster mill is used.
-These mills (four high and cluster) requires lower energy and
force . But the reduction of stiffness, which over come
using backup rolls. These backup rolls are larger and
contact the back side of the smaller rolls.
-Four high mills has four rolls, Two small and Two large.
-More than four rolls, known as cluster mill. Use for hot roll
wide plates, most cold rolling applications and to roll foils.
-Blooming and slabbing mills, being the preparatory mills to
rolling finished rails, shapes or plates.
-Mills classified by product produced:
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International Conference on TIM, 2012, Nepal
Mill-configurations
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International Conference on TIM, 2012, Nepal
-Billets mills- three high- rolls diameter 24-32 inch,
preparatory mills for the bar and rod.
-Beam mills-three high –rolls diameter 28-36 inch,
preparatory for heavy beams and channels
-Rail mills- 26-40 inch roll diameter.
-Shape mills- 20-26 inch- smaller size beams and channels
and other structures materials.
-Merchant bar mill- 16-20 inch.
-Small merchant bar mill- 8-16 inch.
-Rod and wire mills- 8-12 inch.
-Hoop and cotton tie mills, similar to smaller merchant bar
mills.
-Armour Plate mill- 44-50 inch
-Plate mills- 28-44 inch
-Sheet mills and Universal mill.
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International Conference on TIM, 2012, Nepal
Tandem Mill:
The mill where rolling is done in one pass. Tandem
mill there are several stands and reduction take place
successively. Stand ranges from 2 to 18.
Micro Mill:
This is characterized by single strand continuous
casting rolling process featuring ultra-high speed
caster in line bar quenching & tempering and direct
rolling bundling system organized in an extremely
compact layout.
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International Conference on TIM, 2012, Nepal
Over View of Presentation
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•
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•
•
Rolling
Mills
Process & Profiles
Development & Innovations
Nepalese Scenario
Conclusion
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International Conference on TIM, 2012, Nepal
Process & Profile
-Roll Bending: Producing cylindrical shaped product.
-Roll forming: continuous bending operation in which a long
strip of metal is passed through consecutive sets of rolls or
stands each performing only an incremental part of bend,
until the desired cross-section profile is obtained.
-Flat rolling: Material fed in between two rolls, basic form of
rolling with the starting and ending material having a
rectangular cross-section.
-Foil rolling: Specialized rolling, used to produce foil of sheet
metal thickness less than 200µm (0.0079 in).
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International Conference on TIM, 2012, Nepal
-Ring rolling: It is specialized type of hot rolling that increases
the diameter of a ring. The work-piece is placed between
two rolls an idler roll, which another roll, called the driven
roll, presses the ring from the outside.
-Structural shape rolling: Cross-sections of continuously
rolled structural shape, showing the change induced by
each rolling mill.
-Controlled rolling: It is type of thermo-mechanically
processing which integrates controlled deformation and
heat treating. In order to achieve the entire process must
be closely monitored and controlled.
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International Conference on TIM, 2012, Nepal
Over View of Presentation
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•
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Rolling
Mills
Process & Profiles
Development & Innovations
Nepalese Scenario
Conclusion
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International Conference on TIM, 2012, Nepal
Development & Innovation
-Earliest rolling mills were slitting mills, passed flat bars
between rolls to form a plate of iron, introduced Belgium
to England in 1590.
-Early time, all work done manually.
-1759 Thomas Blockley patent the polishing and rolling
metals technology.
-In 1766 first tandem mill patent to Richard ford of England.
It was for hot rolling of wire.
-Modern rolling practice started at end of eighteenth century
1783.
-Developed by Henry Cort, using grooved rolls.
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International Conference on TIM, 2012, Nepal
-This mill produced 15 times more output per day compared
to previous mills.
-In 1820, first rail rolling mill was established.
-Industrial revolution at end of eighteenth century and
beginning of Nineteenth century brought revolution in
rolling mill technology.
-In 1850, 20 feet long, 3.5 feet wide, and 7/16 inch thick and
1,125 pounds weight plate was produced in England.
-In 1853 three high mills introduces for heavy section rolling.
-At end of Nineteenth century, more concentration on R & D.
-Started automation and less hazardous conditions.
-In 1964, mini/micro rolling mills.
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International Conference on TIM, 2012, Nepal
Over View of Presentation
•
•
•
•
•
•
Rolling
Mills
Process & Profiles
Development & Innovations
Nepalese Scenario
Conclusion
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International Conference on TIM, 2012, Nepal
Nepalese Scenario
-Brought every materials from outside.
-50 year back- a rolling mill started.
-Technology compared was eighteenth century. It was tandem mill.
-35 years back, another two/three mills started, technology is
similar to first one.
-Technology bought from India.
-From today few year back, few rolling mill upgraded to more
advanced mode of technology, which is nineteenth century
technology.
-There is no any micro/ mini mills .
-Lack behind the technology and management.
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International Conference on TIM, 2012, Nepal
Conclusions
- The quality, safety, management and time leads to
new technology innovations at all time.
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International Conference on TIM, 2012, Nepal
THANK YOU
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