bài giảng vẽ cán phần 5 pot

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ME 4563 Fall ’05 Dr. S. Haran
Casting & Hot Rolling
Casting & Hot Rolling
–
–
a schematic
a schematic
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ME 4563 Fall ’05 Dr. S. Haran
Slab
Hot mill
Roller table
Warm mill
Take-up roll
Hot Rolling Mill Design
Hot Rolling Mill Design
•
•
Basically the same as cold mills, but designed for
Basically the same as cold mills, but designed for
higher temperatures and are reversible
higher temperatures and are reversible
•
•
Typically have edging rolls to control thickness
Typically have edging rolls to control thickness
•
•
Often have a warm mill at the end

Often have a warm mill at the end
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ME 4563 Fall ’05 Dr. S. Haran
Hot Rolling Mill Design
Hot Rolling Mill Design
•
•
Basically the same as cold mills, but designed for
Basically the same as cold mills, but designed for
higher temperatures and are reversible
higher temperatures and are reversible
•
•
Typically have edging rolls to control thickness
Typically have edging rolls to control thickness
•
•
Often have a warm mill at the end
Often have a warm mill at the end
Slab
Hot mill
Roller table
Warm mill
Take-up roll
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ME 4563 Fall ’05 Dr. S. Haran
Hot Rolling Process
Hot Rolling Process
-

-
Example
Example
•
•
Start with 12in. thick slab, 20 feet long
Start with 12in. thick slab, 20 feet long
•
•
Hot mill converts to 2 in thick slab, 120 feet long with
Hot mill converts to 2 in thick slab, 120 feet long with
11 passes (six forward and 5 reverse)
11 passes (six forward and 5 reverse)
•
•
Front end sheared off to eliminate alligatoring
Front end sheared off to eliminate alligatoring
•
•
Warm mill converts this to
Warm mill converts this to
roll
roll
of sheet 0.25 in thick,
of sheet 0.25 in thick,
960 feet long
960 feet long
•
•
Rolls more easily handled by overhead cranes to

Rolls more easily handled by overhead cranes to
transport it to cold mills than 1000 ft long slabs
transport it to cold mills than 1000 ft long slabs
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ME 4563 Fall ’05 Dr. S. Haran
Overall Process for Sheet and Plate
Overall Process for Sheet and Plate
•
•
Cast ingot
Cast ingot
•
•
Scalp (not always)
Scalp (not always)
•
•
Reheat and homogenize (uniform)
Reheat and homogenize (uniform)
•
•
Hot roll in reversing mill to ~1
Hot roll in reversing mill to ~1
-
-
2 in thick
2 in thick
•
•

Cut off ends (alligators)
Cut off ends (alligators)
•
•
Warm roll to 0.1
Warm roll to 0.1
-
-
2 in thick
2 in thick
•
•
Heat treat to recrystallize (sometimes)
Heat treat to recrystallize (sometimes)
•
•
Cool
Cool
•
•
Cold roll to finish thickness
Cold roll to finish thickness
•
•
Heat treat (where appropriate)
Heat treat (where appropriate)
•
•
Results in material which must be further worked
Results in material which must be further worked

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ME 4563 Fall ’05 Dr. S. Haran
Hot Rolling
Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Hot Rolling
Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Rolling
Rolling
Mill
Mill
Hot Rolling
Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Hot Rolling
Hot Rolling
Closer Look
Closer Look
Hot Rolling
Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Continuous
Continuous

Steel
Steel
Casting Line
Casting Line
rolling out
rolling out
billets
billets
Hot Rolling
Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Continuous
Continuous
Rolling of
Rolling of
Billets
Billets
Hot Rolling
Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Steel Billets
Steel Billets
Steel Slabs (from slab caster)
Steel Slabs (from slab caster)
Billets
Billets
Casting

Casting
Hot Rolling
Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Hot rolled strips
Hot rolled strips
being coiled
being coiled
Hot Rolling
Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Rolling of
Rolling of
Rails
Rails
Hot Rolling
Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Hot Cutting
Hot Cutting
the rolled
the rolled
Rails
Rails
Hot Rolling

Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Section of the
Section of the
Mill where
Mill where
rolling is
rolling is
taking place
taking place
Hot Rolling
Hot Rolling
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ME 4563 Fall ’05 Dr. S. Haran
Profiled color
Profiled color
-
-
coated steel
coated steel
sheets
sheets
U
U
-
-
section long bars
section long bars

Rolling
Rolling
–
–
Further Processing
Further Processing
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ME 4563 Fall ’05 Dr. S. Haran
Wire rods in
Wire rods in
a coil
a coil
U
U
-
-
section long bars
section long bars
Rolling
Rolling
–
–
Further Processing
Further Processing
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ME 4563 Fall ’05 Dr. S. Haran
Cold Rolling
Cold Rolling
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ME 4563 Fall ’05 Dr. S. Haran


Hot rolled coil is commonly cold rolled (also known as cold
Hot rolled coil is commonly cold rolled (also known as cold
reduced).
reduced).


The strip is first de
The strip is first de
-
-
coiled (uncoiled) and then passes through a
coiled (uncoiled) and then passes through a
series of rolling mill stands which apply pressure to the strip
series of rolling mill stands which apply pressure to the strip
and
and
progressively reduce its thickness
progressively reduce its thickness
-
-
down to as low as 0.15 mm.
down to as low as 0.15 mm.


The strip is then recoiled.
The strip is then recoiled.



Cold rolling processes are also used to improve the surface
Cold rolling processes are also used to improve the surface
quality of the steel.
quality of the steel.


Cold rolling also has the effect of hardening steel, so cold
Cold rolling also has the effect of hardening steel, so cold
reduced strip is subsequently annealed: a process of very
reduced strip is subsequently annealed: a process of very
carefully controlled heating and cooling to soften it
carefully controlled heating and cooling to soften it
Cold Rolling
Cold Rolling