Coil Industry

7/30/2019 Coil Industry

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Pressing, Cooling and Coiling China Steel HSM #1 Major Upgrade Project

Wlodzimierz FilipczykSr. Systems/Application Engineer TM GE Automation, Salem, VA

1501 Roanoke BlvdSalem, Va. 24153 - USA

Tel. 540-387-7518, Fax. 540-387-7890e-mail: [email protected]

Lin, Chen-HuaAssistant General Superintendent Rolling Mill Dept. II China Steel Corp.

1 Chung Kang RoadHsiao Kang KAOHSIUNG 81233, Taiwan, ROC

Tel. 886-(7) 802-1111 ext.2581, Fax. 886-(7) 805-1174

e-mail: [email protected]

KEY WORDS:Hot Strip Mill, Sizing Press, Laminar Cooling, Coil Presentation, Automation System, Project Schedule

INTRODUCTION

The 1730 mm high production Hot Strip Mill #1 is a part of the China Steel Corporation (CSC) steel complex located in Kaohsiung, insouthern part of Taiwan. The mill was expanded and modernized several times during last two decades. The last modernization projectwas conducted during the year of 2004 and fully completed in the first half of 2005. The major modifications to the mechanical andelectrical equipment were implemented both on the entry and exit side of the mill. The Slab Sizing Press was installed in front of theRoughing Mill and on the other end all new Runout Tables, Laminar Cooling System, Downcoilers and Coil Handling equipment.The mechanical equipment was supplied by IHI (SSP) and MH (Coilers and ROT Cooling) from Japan. The electrical equipment and

automation was supplied by TMEIC GE Automation Systems from USA.

MILL CONFIGURATION AND BASIC DATA

The Basic Mill Equipment:

- Four (4) Walking Beam Reheating Furnaces- Slab Sizing Press (new - original stand alone Edger VE1 was removed)- Reversing Roughing Mill #1- Reversing Roughing Mill #2 with front and back Edgers- Closed coupled RM #3 and RM #4 with front Edgers- Intermediate (Delay) Tables with Thermal Covers- Crop Shear- Seven (7) Stand Finishing Mill with Interstand Cooling- Runout Tables (new)- Laminar Cooling System (new)

- Three (3) Downcoilers (new)- Coil Conveyors with Binders, Coiler shape meters, Scales and Markers (new)- Automatic Surface Inspection System (new)

The Basic Mill Data:Slab dimensions range: Thickness: 150 to 270 mm; Width: 700 to 1575 mm; Length: max.9000 mmStrip dimensions range: Thickness: 1.2 to 25.4 mm, Width: 700 to 1575 mmTypes of steel grades rolled: Ultra Low, Medium and High Carbon, HSLA, Stainless, DP, API X80 and TRIP


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Figure 1. Simplified Mill Layout

THE SCOPE OF THE MILL MODERNIZATION

The whole scope of the mill revamping was split into two separate projects:- Downcoilers and Strip Cooling System Modernization- Slab Sizing Press Installation

Although separate projects, they were coordinated and executed in parallel to optimize the utilization of the production shutdowns.

THE DOWNCOILERS AND STRIP COOLING MODERNIZATION

The Main Objectives:

- To increase final strip thickness from 20 to 25.4 mm- To produce special steel grades which meet specific structural requirements such as DP, API, TRIP grades- To achieve better coil presentation and quality (telescopicity, head marks etc.)- To improve the operation of the coil handling area

In order to achieve these goals the following equipment and functionality were implemented.

Mechanical equipmentThe mill was originally equipped with three downcoilers, two identical and third one with higher power and hydraulic actuatorsdedicated to coil heavy products. Those were replaced by three identical universal wide- range new coilers. Each new coiler isequipped with four unit rolls and variably expanded mandrel. The Sideguides, Pinch Rolls and Unit Rolls have hydraulic gap/forceactuators.In order to provide ability of coiling heavier and much harder products, the mandrel power was increased by 35% to 1100 kW percoiler. The coil diameter ranges from 1140 to 2200 mm with coil weight up to 37 tons.

The coil handling area was completelyreconstructed. Three walking beamconveyors were installed to transportthe coils from individual coilers to thechain driven cross conveyors. At theend of the chain conveyors the coils arepicked up by the overhead crane andtransported to the coil storage bay. Thenew shuttle car provides the coilhandling between individual conveyorsand new coil inspection station. The

banding machine, weight scale andpaint marker (actuated by robotic drivenarms) are installed at each individualconveyor. In addition, at each conveyorthe laser coil shapemeter was placed tomeasure the straightness of coilsidewalls.

Figure 2. New Coiler Area


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In order to provide better thin gauge strip transport and to fit the tables geometry into the new cooling system, the FM Run OutTables (ROT) were modified to decrease the roller pitch to 360 mm. The total number of rollers, including new carry over tables wasincreased to 435 rollers. The existing 295 rollers were re-used in the new ROT arrangement.

The requirement for producing new steel grades with specific metallurgical properties resulted in the implementation of new laminarcooling system on ROT. The water capacity remained the same as in the original system; however the characteristics of the coolingsystem were significantly changed. The number of individually controlled valves was increased to provide better coolingcontrollability. Each header is fed directly from the overhead tank through the individual pipe, thus eliminating the interactionbetween the sprays (cross-talk) during turn on/off actions. The ROT spray system characteristics are as follows:

432 spray controllable units (240 top and 192 bottom) in 15 banks.o Banks 1-4 and 13-14 are intensive banks

- 16 controllable units top, each 1700 lpm flow- 8 controllable units bottom, each 1700/2380 lpm at low/high flow

o Banks 5-12 and 15 are fine banks- 16 controllable units top, each 850 lpm flow- 16 controllable units bottom, each 850 lpm flow

Total available flowo 4 pump operation - 256 m**3/min (256,000 lpm)o 5 pump operation - 320 m**3/min (320,000 lpm)

Figure 3. ROT Laminar Cooling System

Electrical Equipment and Control SystemNew coiler electrical building was constructed on the drive side of the mill. The new control rooms host the switchgear, transformer

drives and Level 1 controllers. All new motors and drives are based on variable frequency state of the art AC technology.The new control system was based on the following platforms:

LEVEL 1 - GE Innovation Series Controllers

HMI - Wonderware ArchestrA system

LEVEL 2 - PC Windows based with Database Server

LEVEL 1 controller for laminar cooling controls directly all ROT Cooling Spray valves. This controller called Spray Director isresponsible for executing Coiling Temperature Control (CTC) model references in timely manner, as well as performs sample trackingand provides feedback information to the model.


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LEVEL 1 Coiler Controllers perform standard functions of strip tracking, reference distribution and sequencing from FM Exit to CoiConveyor Exit. The most important for the coil quality are however the regulating functions implemented in individual coilercontrollers. These include:

Various Coiler Sideguides Operating/Coiling Modes:o For Head and Tail of the Coil - Short Stroke (Head & Tail, Head Only, Off)o For Body of The Coil: Constant Force, Constant Gap, Oscillation (Zigzag)o Symmetry Selections: Symmetrical, Asymmetric Drive Side, Asymmetric Operator Side

Various Coiler Pinch Roll Gap Operating/Coiling Modes:o For Tail/Head and Body: Constant Gap, Constant Force (Total or Independent)o For Tail Approach: Tail Fanning (Unipolar vs. Bipolar Force Regulator)

Continuous (Step-less) Coiler Mandrel Expansion

Various Unit Roll Gap Operating/Coiling Modes:o For Head End of the Coil: Constant Force Modeo For Head End of the Coil: Quick Opening Control (QOC) a.k.a. Automatic Jump Control Gap/Force Modeo For Head End of the Coil: QOC Gap/Gap Modeo For Body of The Coil: Thin/Thick Strip Mode

LEVEL 2 existing HSM#1 system is based on Alpha VMS HW and includes the functionality. to control and set-up the entire mill.The functionality of CTC model as well as spray control (Spray Director) was removed from this computer.New CTC model was implemented in new PC Windows based computer, while laminar and interstand sprays control wasimplemented in new Innovation Controller (Spray Director).The communication between new Level 2 computer and new Level 1 is done via industrial Ethernet control network using GlobaMemory concept.

The communication path using inter-process services messaging was established between old existing Level 2 and new CTCcomputer. The required reference data such as bar data, Time-Velocity-Distance profile etc. from existing Level 2 and requiredfeedbacks (such as FTC/CTC interlocks, logging data etc.) to the existing Level 2 are transmitted via this path.Besides standard functionality to achieve desired coiling temperature CTC model supports strategies using various spray patternsincluding interrupted cooling (dual phase). Some of the most important features of CTC model include:

Flexibility in applying the Spray Patterns:o The activation sequence order of each top and bottom spray can be specified in each pattern database table

ORo CTC will calculate the order in which sprays are used so as to achieve a target cooling rate, target air cooling

time, forward or reverse activation, and differential cooling rates for top and bottom surfaces of the pieceTarget rates, times, and forward or reverse order are specified in each pattern database table. Calculatedpatterns can be used for both interrupted cooling where an early and late quench zone are separated by an aircooling region and for non-interrupted cooling. In the case of non-interrupted cooling a target air cooling time is

applied as a dry zone at the beginning of the spray pattern sequence. Flexibility in prioritization of the control targets for interrupted cooling based on the specific requirements for particular

steel structures e.g. bainitic vs. martensitic. The basic priority is as follows:1. Coiling Temperature2. Intermediate Temperature3. Early Zone Cooling Rate4. Dry Zone Time

Variable control sample length as a function of strip thickness

Comprehensive recording of the strip status along the whole length of the ROT. In addition to temperatures, massflowand water flow such parameters like heat losses, ferrite content etc. are logged at the exit of each cooling bank.

INSTRUMENTATION New pyrometers were installed in the intermediate and final control locations. Both top and bottom surfacetemperature is measured. The measuring range had to be expanded in the low temperature range down to 200C. At the time of the

installation, single pyrometer covering full range (200 to 800C) with adequate response time was provided by Land. Double sets ofpyrometers had to be used for CTC feedbacks. The laser velocimeter was installed at the coiler entry location to provide more accuratestrip speed measurements which is especially important for short bars where strip tails out of the FM before entering coilers.

HMI system is based on the latest Wonderware ArchestrA architecture. This is an innovative approach to application integrationand data interfaces in HMI system. The centralized repository contains the definitions of process data objects (roller table, servo valveelectrical drive etc.). These can be simply instanced and then deployed for the specific application. This provides centralizedmanagement of data interfaces, which allows for easy and quick modifications and additions in the HMI system.Two sets of the control desks with HMI terminals were installed: one in the Coiler Pulpit, one in FM Pulpit (future remote operation).


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SLAB SIZING PRESS INSTALLATION

The Main Objectives:- To improve caster efficiency by minimizing the number different slab widths- To increase the width reduction capability of the mill resulting in faster order execution for customers- To increase the capability of slab head/tail tapering (pre-forming) for yield increase and better final width uniformity

Mechanical equipment

The Slab Sizing Press (SSP) was installed in front of the first RM stand (R1) in the place of old stand alone edger (VE1). This theflying type of the press which means that the slab is continuously moving while pressing is performed. Besides SSP, othermechanical devices in the RM area were added or replaced. The new mechanical equipment in RM area includes:

RM Entry Descale Box

SSP Main Core with feed and hold down rolls

SSP Entry Table (with Table Lift) and SSP Exit Table

SSP Entry, R1 Entry, R2 Entry/Exit Sideguides (Hydraulic)

R2 Entry Centering Devices (2)The basic characteristics of SSP are following:

Max. draft = 350 mm

Pressing transport speed = 0.3 m/sec

Max. Force = 2200 tons

Main Motor Power = 3400 kW

Figure 4. Slab Sizing Press

Electrical Equipment and Control SystemSSP is equipped with all AC motors and drives. The Main Motor was installed in The RM Motor Room on the elevated foundation

since the main shaft is connected to gears mounted on the top of the press. SSP drives were located in the new control room inside theRM Motor Room. The Main Drive is based on the most advanced semi-conductor technology utilizing IEGT elements.LEVEL 1 controller (Innovation Series) was connected to the existing RM control network. The complete control functionality forSSP: micro-tracking, position and pressure regulators, die synchronization, sequencing and auxiliary systems control is performed bythis controller. Due to the SSP mechanical capability of on-line dies reversal, several pressing modes were possible to implement:

Forward Press

Reverse Press

Head/Tail Running Pre-forming

Head/Tail Stopped Pre-forming


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LEVEL 2 control for the SSP involves RM Setup Model (RSU). Existing RSU model functionality was augmented by the addition ofSSP module to calculate the setup for the press and scan associated process feedbacks. RSU allocates total width reduction requiredamong SSP and RM Edgers and then calculates the SSP setup. The references and auxiliary calculated values include: die gapopening, press draft, head, body and tail deformation forces, hold down roll force, head, body and tail width reduction ratios, head andtail pre-forming lengths, exit head, body and tail thickness, elongation ratio, travel time.Some of the process feedbacks such as the measured gap, force, temperature etc. are used for model analysis and off line tuning. Theadaptive loop is based on the width feedback measured on the exit of R1 Stand.

INSTRUMENTATION New width gauges with thermal profile measurement capability were installed in front of SSP and at the exitof R1 Stand. At the entry to SSP the slab width is scanned and it is used to generate the final RSU setup. The R1 Stand exit gauge isused for model feedbacks and feedforward setup. The thermal profile is used for off line analysis of furnace heating practices andcorrelation with bar camber.

PROJECT IMPLEMENTATION

The two projects described above were lead separately during the bidding and contractual phase. However, the implementation in themill was fully coordinated to take full advantage of the planned mill down time. The two projects had different mechanical suppliersbut the same electrical/automation supplier. The coordination of both products resulted also in optimum use of electrical supplierresources, thus. minimizing the installation and commissioning cost.The project started in 2003 with the contracts signed in the first half of the year. The general concepts of the implementation areshown in the Figure 5.

Figure 5. Project Implementation Concepts

*Original Down coiler were equipped with three unit rolls only


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General Project Schedule

The contract for the Coiler Project was signed in January 2003 and for SSP Project in June 2003. The mechanical and electricalengineering started at the same times. The civil engineering work started in the Coiler area in the second half of 2003.COILERSThe foundations for new Coilers and new coil handling area as well as coiler electrical building were erected by the end of 2003.The new mechanical and electrical equipment for Coilers was delivered to site in 1Q of 2004. The mounting and installation of theCoiler #4 and #5 equipment was completed in 2Q of 2004.The start up of the electrical and automation equipment commenced in June 2004. The coiler area fluids systems were commissionedfirst to make sure existing coilers operation is supported by new control system. The new Coilers #4 and #5 were started, checked andtuned under no-load conditions while mill was running with existing 3 coilers. Having the new equipment and control logicthoroughly checked out before putting it to rolling operation contributed to very smooth switchover.

Twelve (12) days shutdown for Coiler #3(Coiler #1 remain in operation) in August 2004 was used to prepare for installation ofcarry over table between existing Coiler #3 and new Coiler #4. The cobble catcher was moved from behind Coiler #3 to Coiler #2For next two weeks the mill was operating with 2 existing coilers while the carry over table installation was completed. After this, themill was shutdown one day for electrical test and the cobble catcher was moved behind Coiler #5, thus 2 new coilers were added to themill operation. Due to the mechanical obstruction existing Coiler #3 had to be put out of service, so mill was then running with 4active coilers. This operation continued until the main shutdown started in early December 2004. During this time the old Coiler #3was being decommissioned and new mechanical and electrical equipment installed as much as possible during the mill operation andregular maintenance shutdowns.

SSPThe first step of Slab Sizing Press installation was removal of the stand alone edger (VE1) between the Furnace #1 and RM Stand #1.The edger had to be removed since the short distance from the furnace to the first stand did not allow for adding the SSP in the spaceavailable. This was done partially during rolling operation. The mill went for 14 day shutdown in January 2004. During this periodthe removal of VE1 was completed, new foundation was erected and temporary bridge table section was installed. The mill thenoperated without VE1 for almost a year until the main shutdown in early December 2004. During this time the civil engineering andmechanical work continued and SSP equipment was put partially into place. The electrical and control equipment for SSP and RMguides was installed in 4Q 2004.

Month

Contracts Signed (CLR-J an 03, SSP- J un03)

Design, Engineering & Manufacturing (2003 +)

Civil Engineering (CLR - 2003+) Coilers SSP

Equipment Delivery to Site Coilers SSP

Installation of Mechanical Equipment Coilers Coilers, ROT, Sprays, SSP

Installation of Electrical Equipment Coilers SSP

Tune-up. Testing and No Load Runs Coilers SSP/Coilers

Operation in Hot Rolling

* Without Vertical Edger 1

* With Two Old Coilers

* With Two Old Coilers & Two New Coilers

* With ALL New Equipment

Level 1 Control and Mod els Tune-up

Final Acceptance

Shutdown

14 days 1 day 30 days

Shutdown Shutdown

Apr May

2004 2005

Dec J an Feb MarAug Sep Oct NovJ an Feb Mar Apr May J un J ul

Figure 6. Project Schedule


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MAI N SHUTDOWNThe main shutdown was scheduled initially for 40 days, and then planned for 35 days and finally due to the excellent execution of themechanical and electrical work was shorten to 30 days. This shutdown combined the activities for both projects. The major tasks:

Removal of temporary SSP bridge tables and existing RM Sideguides

Installation of new SSP and RM mechanical equipment, piping and wiring

SSP start-up, cold test and then hot load test

Removal of old Runout Tables, Laminar Cooling System, Coiler #1, Coiler #2, Conveyor area equipment

Civil engineering , mounting and installation of new ROT and laminar Cooling System

Completion of mounting and installation of Coiler #3 Mounting and installation of conveyor equipment, scales, banders and markers

Start-up of all new equipment and no load tests

Coordinated Ghost Bar rolling

MILL STARTUPThe mill started regular production on December 31, 2004, 5 days ahead of the original schedule.The mill ramp-up to production was very rapid, since within FEW HOURS after start-up mill was up to the normal level ofproduction. Taking into account the scope of the new equipment and supporting control functions, which had to perform flawlesslywithin such short time, this was an enormous accomplishment.The quality ramp-up was very quick as well, since within the first week, new CTC performance was at the level (or better) of the oldsystem. The number of coils out of tolerance or coils required reclassifications (due to CT) was extremely low and far belowexpectations. Within first 5 weeks of rolling (ca. 12,000 coils) only 40 coils needed to be diverted as different quality but were still

sellable products.The initial tune-up work has been completed by the end of January 2005 and model engineer returned to Salem.The final CTC tuning was completed in April 2005. The tune-up which required special attention included specialty steels wheresingle coils are rolled, results are tested, and changes made as necessary with the goal of achieving the target material properties. CTCpattern and rate calculations are being configured to meet the bainitic and martensitic control priorities.The SSP was put into operation within first week of January 2005. Within 3 days of operation the drafts taken were increased tomaximum of 350 mm.

HIGHLIGHTS AN MILESTONES

The Coiler project started in January 2003, SSP in June 2003.

The delivery of mechanical equipment 16 months for Coilers, 16 months for SSP

The delivery of electrical equipment 14 months for Coilers, 14 months for SSP

The mill began the operation with all new equipment in January 2005

The final acceptance test was performed in May 2005 Three (3) production shutdowns in 2004 were dedicated to the project execution

Total extra days of shutdowns (beyond routine maintenance shutdowns) = 24 days

RESULTS AND SUMMARY

Results

The final results can be presented using the process measurements and production data and compare them against the objectivesspecified or expected for each project.

CAST SLAB WIDTH RANGEThe number of different slab widths ordered from the caster was reduced from 19 to 7 due to the increase in width reduction capabilityby SSP. The caster efficiency was significantly increased.For the HSM#1 85% of cast slab widths are 1050, 1270/1280 and 1420mm, thus the mold change frequency is extremely reduced.The financial gain for the caster department results in annual savings of about 2M$.

WIDTH PERFORMANCEAfter implementation of SSP and retune FM width spread model, the width performance (as measured on FM Exit) is increased from90% to 95% 4 mm of all rolled length.


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MATERIAL PROPERTIES FOR NEW PRODUCTSCSC primary goal with respect to material property was to be able to use dual phase cooling to produce bainitic and martensitic steel.For bainitic product the goals are:

To quench to an intermediate temperature

To provide an air-cooling region (fixed and narrowly constrained; to allow ferrite formation in an approximately isothermasetting.

To quench to a final temperature in the range of 400 CFor martensitic product the goals are

To quench to an intermediate temperature To provide the maximum amount of air cooling (the intermediate temperature can be sacrificed to provide max. air time)

To quench as rapidly as possible to a final temperature in the range of 200deg C.These goals were achieved with new ROT cooling system and CTC model functionality.

COILING TEMPERATURE PERFORMANCECTC performance was improved to achieve 15 C for 97% of all rolled and evaluated products.

COIL PRESENTATIONNew measuring devices (laser shapemeter) were installed at the exit from each coiler for automatic and tactile less measurements ocoil telescopicity (side wall).

Figure 7 Coil Telescopicity Report

The coil parameters related to its coiling process and coiler equipment and control performance were achieved at the following levels:

Telescopicity and Wrap protrusion within 15 mm

Head End marks:o 1-st wrap


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DECREASE IN MILL DELAYSThe production delays due to the electrical equipment before and after revamp of Down Coiler area was dramatically changed. See thefollowing table, which shows the total outage is 39 times with 4851 minutes delay in 2004 and ZERO in 2005. A ROT motor trippedtwice and was replaced in Jan. 2006 due the stuck bearing.

Comparison with Times of fault/Total time lost in minutes

Year 2004 2005~Jan2006

Mandrel 14/747 0

Pinch Roll 3/85 0

Wrapper Roll 4/57 0

Run Out Table 18/3962 2/127

SURFACE INSPECTION SYSTEM BENEFITSThe benefit of Automatic Surface Inspection System can be summarized as follows:

Year 2004 2005

Coil inspected due to defect (times/per month) 39.5 6

Coil rejected resulted from roll mark defect (ton/per month) 496.73 275.5

Coil rejected owing to rolled in scale (percentage of production) 0.121% 0.077%

Any surface defects are flagged from the system, thus they can be handled much more quickly than before.

BENEFITS FROM SHORTENING OF ROT ROLLER PITCHShortening of the ROT roller pitch has resulted in the possibility of reducing the hot head end of the very thin strip from minimumof 100 meters to 0 with stable coiler thread.

COIL SHAPE DEFECTSAll Coil shape defects (including Telescope, Protrusion, Loosely Wrapped Coil, Oval Coil, Not Matching Diameter) were reduced asshown below.


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COIL SURFACE DEFECTSCoil surface defects (include Gouge, Pinch Roll Mark, Pincher, Rolled-in Object, Head Mark) were reduced from 23.6% to 15.4% dueto the improvement in the coil shape. The pincher defect was increased from 3.6% to 36.2% because of changing to the hydraulicsystem. After improving the control of pinch roll and side guide logic, the cut length weight percentage due to pincher is reduced from0.28% to 0.16%.

82.8100 96.4 97.3 97.3

0

20

40

60

80

100

OKYield(Coil%)

Gouge Pinch

Roll Mark

Pincher Rolled In

Object

Head

Mark

BeforeRevampingAfter

COIL SURFACE DEFECTS

The thickness of the products was increased to 25.4 mm with excellent coil presentation results.

Thickness: 25.4mm SS400 Thickness: 20.0 mm APIX80


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Summary

The SSP and Coiler were large size projects providing significantly positive results on mill production both in capability and quality.The scheduled shutdowns were necessary for such large amount of mechanical and electrical equipment to be installed. Beside majorconfiguration change at the front of the mill (SSP addition), the entire mill exit area (from last FM Stand to Coil Storage) was replacedwith new equipment and control.Careful and coordinated approach to the phased implementation resulted in minimum production disturbances during startup periodsafter shutdowns. The ramp ups to the normal production levels were almost non-existent while quality was also quickly brought to thelevels higher than before modernization.

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