Induction Work Roll Heating System - Flatness Control with Edge Heating System or Full Width Work Roll Heating for Flatness and Complex Profile Control

1. Induction Work Roll Heating Technology
for
Superior Rolling Mill Shape Control

2. 2
1
3
Backup roll
Work roll
1) Roll separation forces can cause work rolls to bend
around the sheet, producing loose edges.
2) Hydraulic edge jacks and stiff backup rolls partially
counter “bending around the sheet”.
3) Eventual work roll thermal expansion can generate a
thermal crown, producing tight edges.
The Challenge
• Mill Speed reduced to produce
thin gauge sheet;
• Use of conventional coolant
sprays and actuators aren’t
sufficient to control Flatness;
• Reduce or eliminate edge cracks
and strip breaks;
• Unnecessary slitting sheet edges
due to flawed edge profile;

3. Work
roll
Backup
roll
Segmented
shape meter
Sheet
Lubricant sprays are used to reduce roll separation
forces and cool the rolls, to remove debris and
reduce roll wear.
Conventional Corrective Tools

4. Segmented
shape meter
Sheet
Automated
lubricant sprays
Center buckles & tight edges
Sheet width Sheet width
Shape
profile
Spray
outputsController
Target Shape
Zone-controlled lubricant sprays were
invented to correct the gauge, profile, and
shape automatically, by cooling the work roll
where the sheet is thin, overworked or loose
however it doesn’t work efficiently in
demanding shape profiles.
Using only cooling sprays

5. Segmented
Shape Meter
Automated
Induction Workcoils
Sheet
Automated
Lubricant Sprays
More uniform shape profile
Sheet width Sheet width
Shape
Profile Controller
Target Shape
Zone-controlled lubricant sprays combined
with induction edge-heaters correct basic
shape variations more effectively, by
cooling the work roll where needed and
heating the edges.
Spray Outputs with
Edge-Assist
With Comaintel Induction Edge Heating

6. Loose edges
Compound shape
Center buckles & tight edges
Sheet width
¼-buckles & tight edges
However, set-up variations, machine
wear, material variations, and
transient effects (progressive work roll
thermal deformation) can produce
complex shape profiles that change
throughout the production cycle.
Limitations and Opportunities

7. Sheet
Automated
lubricant sprays
Sheet width Sheet width
Controller
Target Shape
Zone-controlled lubricant sprays and
induction workcoils correct even complex
shape variations, by both heating and
cooling the work roll to directly attack
loose and tight regions of the profile.
¼-buckles & tight edges
Shape
Profile
Segmented
Shape Meter
Full-range Actuator
Outputs
Automated
Induction Workcoils
The Optimal Approach

8. Induction Work Roll Heating Technology
High-frequency
(≈25 kHz) surface
eddy currents
OptiCoil inductor is
essentially half a
transformer
Energy transfer = f(1/g2)
g
Heats from the outside, to put the
heat on the surface where it’s
needed, for faster response
Designed to optimally heat only
ferrous materials. Electrical
resistance must be low enough to
permit generation of high eddy
currents at negligible voltage
levels, but high enough to cause
resistive heating.
OptiCoil
Concentrating the flux in the center
and using high-frequency maximizes power
transfer and reduces sensitivity to gap.
Patented OptiCoil is flat (doesn’t
need to match roll curvature), so it
fits any work roll diameter and
accommodates gaps up to 6 mm.
Work Roll

9. A typical roll edge induction heater has
two (2) Opticoils installed on roll edges

10. Actual heating zone width
with Comaintel 30 mm heaters

11. Roll face temperature rise at 4 kWatts

12. Optimal Flatness Control with Full Width Induction Heating
What:
• Staggered Liquid Cooled Induction Coils for Full Width Flatness Control;
• Independent Controlled Induction Coils and Power Module for more
Efficient Flatness Control;
• Most Powerful and Efficient 12 kW Power Modules in the Industry;
Where to use them:
• Pre-Heat Work Roll for Immediate Required Flatness Profile Production;
• Produce Complex Shape Profile with Independent Induction Zone
Heating;
Why:
• Faster Start-Ups;
• Less Waste;
• Increase Mill Speed;
• Reduce Strip Breaks;
• Full Profile Control;
• Produce Complex Profiles;
• Save Energy with highly Efficient Induction Heating (up to 95%).

13. Typical workcoil tight staggered beam

14. A typical full width beam
using Xcore LC (Induction Coils) technology

15. A typical Off-machine Cabinet
for 100 kW/meter power density

16. The effects of air gap on workcoil efficiency

17. Multiple heating zones across roll face
for temperature control

18. Comaintel’s Edge Induction Heater Solution:
Adding Induction heaters on tight edges helps correct the overall work
roll nip pressure profile. This corrects tight edges problems while
allowing cooling sprays to work more efficiently.
Comaintel’s Full Width Induction Heater Solution:
Adding narrow zone Induction heaters full width across the face of the
work roll combined with existing cooling of loose regions significantly
increase sheet shape control range and response.
Both Solutions enable higher quality to be produced
at faster speeds.
Comaintel’s Rolling Mill Induction Heaters