• Clam shell, 4-high, 6-high and solid frame levelers
• During the last 40 years supplied state-of-the-art continuous stretchers and tension levelers to the metals industry
• Downside
– Expensive – Customized cartridges with commercial bearings – No capability of adjustment if an alignment
problem occurs such as foundati1o0n0 msemttlement – No "on-line" roll surface maintenance capability
MEMBER OF FATA GROUP
PRINCIPLES OF TENSION LEVELING
During Tension Leveling . . .
• Unequal strip stresses causing shape defects are equalized • The strip is alternately bent under tension over small rolls,
EXIT BRIDLE
ENTRY BRIDLE
10
FATA HUNTER
MEMBER OF FATA GROUP
PRINCIPLES OF TENSION LEVELING
PROGRESSIVE ELONGATION AS STRIP PASSES AROUND EACH
BRIDLE ROLL
11
• Subsequent development provided a more economic solution by adding a non-driven roller leveler, first with large rolls (6”diameter) - later with smaller rolls
subsequent foundation settlement and misalignment – Commercial bearings, no pillow blocks
• Downside
– Expensive
21
FATA HUNTER
MEMBER OF FATA GROUP
DRIVE SYSTEMS
• Tension Leveling Theory • FATA Hunter History in Tension Leveling • Design Alternates • Process Issues • Flatness and Performances
2
FATA HUNTER
MEMBER OF FATA GROUP
FLATNESS PARAMETERS
• Coil flatness may appear acceptable after rolling under high tension
• A flatness defect may develop after cutting, due to generation by rolling of high non-homogeneous stresses within the strip
FATA HUNTER
MEMBER OF FATA GROUP
TENSION LEVELING PRINCIPLES AND DESIGN
presented by
Prabhaka FATA GROUP
PRESENTATION OUTLINE
AMPLIFIER
The Amplifier Consists of . . .
• (2) Flex Roll Zones • (1) Anti-Crossbow Zone
AFNLTAIT-CTRENOISNSGBZOOWNZEONE
• (1) Flattening Zone #1 FLEX ZONE
• 47 units supplied for:
– Aluminum and Steel – Can Stock, Appliances and Construction Grade
16
FATA HUNTER
MEMBER OF FATA GROUP
DESIGN ALTERNATES
• Tension Bridles • Drive Systems • Leveling Amplifiers • Electrical Drives
19
FATA HUNTER
MEMBER OF FATA GROUP
TENSION BRIDLE - TYPE "B"
• Design
– Bearings / pillow blocks mounted on vertical member – Standard FATA Hunter design
INCOMING STRIP
( = 2)
13
FATA HUNTER
MEMBER OF FATA GROUP
OPERATING PRACTICES
• High Yield Strength Materials (Non Ductile)
– Reduced tension to prevent surface lines
Behaves as a motor to maintain and successively reduce the leveling tension
• Benefits
– Adjustment capability – Cost effective – Commercial bearings and pillow blocks
• Downside
– Non-vertical roll change – Residual moment in frame
#2 FLEX ZONE
9
FATA HUNTER
MEMBER OF FATA GROUP
METHOD OF CONTROL
• By maintaining a velocity ratio between the entry and exit bridles
• For a given velocity ratio elongation stays constant regardless of . . .
I = ( 2 /4) x 2 x 10
12
FATA HUNTER
MEMBER OF FATA GROUP
FLATNESS PARAMETERS
ELONGATION SETTING OF 0.25 GRAPH LINE
RESIDUAL DEFECT OF 25 I-UNITS IN OUTGOING STRIP
17
FATA HUNTER
MEMBER OF FATA GROUP
TENSION BRIDLES
• BRIDLE ARRANGEMENTS – Two Roll – Three Roll – Four Roll
• 3-BRIDLE TYPES – Type A – Type B – Type C
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– Strip Size
– Mechanical Properties
– Metallurgical Properties
– Line Speed
• Work roll penetration is dictated by strip alloy
(yield strength), thickness and incoming flatness
• Excessive Elongation
– May create cross-bow or canoe-shape
– Removal by slight additional reverse bending
• Bending Over Small Rolls
– May create coil set
20
FATA HUNTER
MEMBER OF FATA GROUP
TENSION BRIDLE - TYPE "C"
• Design
– Precision machined frame – Bearing blocks mounted on angle pads
• Benefits
– Excellent rigidity – Vertical roll maintenance – Maximum adjustment flexibility for
causing stress amplification beyond the elastic limit • These stresses being greater than the yield strength, cause
permanent elongation of the longitudinal fiber lengths
• Bridle Drive Configurations
– Rigid Drive: Mechanical
– Hybrid:
Combination of mechanical/electrical drives
– All Electrical: Individual electrical drives
– Removal by series of bends/reverse bends over larger diameter rolls