The document summarizes a new hot strip mill being commissioned in November 1990 for An Feng Steel Co. in Taiwan. The key details are: 1) The mill has a production capacity of 2 million tonnes per year and can roll strips from 1.2-12.7mm thick in carbon and stainless steel. 2) It features two walking beam reheat furnaces, one reversing rougher, a coilbox, six finishing stands, and two downcoilers. 3) The distributed control system partitions control by mill area and function to provide responsive independent operation for real-time performance.

1. / The new An Feng 1675-mm, 2 million tonne/year hot strip mill for rolling 1.2 to
12.7-mm thick carbon and stainless steel Is based on two walking beam reheat
furnaces, one reversing rougher wHh attached edger, one Collbox and six 4-h
all-hydraulic finishing stands together with a sophisticated hierarchical distrib-
uted control system. The millis scheduled to be commissioned In Nov. 1990.
New.1675-mm hot strip mill for An Feng Steel
Co., Taiwan
F. Ronald Vidil, Executive Vice President and General Manager, United Engineering, Inc., Pittsburgh, Pa., and Niles H.
Harvey, Project Manager. General8ectric Co.• Salem, Va.
THE An Feng Steel Co., Ltd. was formed with a commit-
ment to build a new 1675-mm (66-in.) wide hot strip mill to
supply quality products for the Taiwan domestic market.
The plant, covering approximately 37 acres, is located on a
greenfield site in Kaohsiung, Taiwan. In addition to the hot
mill, it includes a water treatment plant, administration
building, roll shop, coil storage building, slab storage and
fuel storage areas.
Upon completion ofa market study, a 2million tonne mill
production capacity was established for the plant. Various
mill configurations were studied to meet the required pro-
duction rates and product mix with an emphasis on cost per
ton, et.ergy conservation, high yield and productivity. As a
result of the study, United selected a Coilbox mill configura-
tion. An Feng agreed with the study conclusions and a con-
tract was signed in Feb. 1988, for supplying the mill. The
first coil is scheduled to be rolled in Nov. 1990.
The contract included: Mitsui-U.S.A. as prime contractor
and commercial coordinator; United Engineering as techni-
cal coordinator, mill and construction engineering supplier;
General Electric as electrical supplier; Stein Heurtey as slab
reheat furnace supplier; and Toshiba for roll grinders. In ad-
dition, all suppliers had supervision of installation, start-up
and commissioning, plus training responsibilities.
Part 1-Mill description
The mill will supply 1000-piw coils from reheated slabs for
mild steel, high-strength low-alloy steel and stainless steel
products (Table I).
Mill layout is shown in Fig. 1. Overall length is 267 metres
(876ft) from reheat furnace to downcoilers. The adoption of
a Coilbox configuration reduced the overall length of the hot
line by approximately 35 metres (115ft) compared to a con-
ventional semicontinuous hot mill.
Fig. 1 - An Feng 1675-mm hot strip mill configt.ll'ation: 1-slab yard; 2-fumace charging; 3-fumace pulpit; 4-slab reheat furnaces; 5-furnace
discharge; 6-slab descallng; 7-reversing rougher; 8-roughing mill pulpit; 9-Collbox; 10-crop shear; 11-Coilbox and shear pulpit; 12-finishing
stands; 13-quick roll changing; 14-finlshlng pulpit; 15-runout table; 1~wncoilers; 17-coil conveyors, weighing and banders; 1!Hjowncoiler
pulpit; 19-coll Inspection station; 20-roll shop; 21-interbay roll transfer cars; 22-coll storage area; and 23-scale pit.
-:· ·::-- ..
..___ -··~
L---~----J
November 1990 Iron and Steel Engineer 39

2. TABLE I Product data
Slaa.
Thlck-.mm
Length, men.
Strip
Thlck-.mm
Wlclth, mm
Coli weight, tonnn
StMI type
25o "'to'
5, 10
150 to 200 • c;''to '6'
4.2, •••
1.2 to 12.7 3.0 to 10.0
650 to 1525(~~·~>W') 650 to 1300
25 10
The basic mill consists of:
• Two walking beam, oil-fired, slab reheat furnaces rat-
ed at 250 tonnes/hr.
• One reversing roughing mill with attached vertical
edger.
• Coilbox.
• Rotary crop shear.
• Six all-hydraulic finishing stands.
• Two hydraulic bumpless wrap downcoilers.
• Two walking beam coil conveyors.
• Complete roll shop.
The facilities include operator control stations located at
the furnace charging and slab identification area, roughing
mill stand, Coilbox and crop shear, fmishing mill including
computer room, and downcoiler and delivery coil conveyors.
One scale pit is located between the rougher and Coilbox
to collect all mill direct water and scale. Scale removal from
the pitinto scale transport vehicles is by overhead clam-shell
crane.
Mill power and speeds are summarized in Table II.
· Basic mill and slab furnace utilities are: direct water,
31,000 gpm; recirculating water, 13,000 gpm; steam, 6800 lb/
hr; and compressed air, 7000 scfm.
Slab heating
Incoming slabs are received under the direction of the fur-
nace charging operator in accordance with the predeter-
mined rolling schedule. Delivered from the storage area by a
slab transporter, the slabs are individually loaded onto the
furnace charging ramp by a radio-controlled overhead crane.
Slab identification and slab weight are entered into the
Fig. 2 - Reversing rougher with
. attached edger.
40 Iron and Steel Engineer
TABLE II Mill power and speeds
Power,
M•ln drive motors hp
ROIJ!Ihlnsl mta 2 x csoo • tooo
lertbl.., 2 x aoo • 1100
,.. "~ '<. 0-J1,.AJ 1"-.1 T"'C '"'f
d~""'f<,, k""Q. ~ t.n..t
Mill~.
tpm
524 to 1048 , I 6~-> t; ?,:W
Finishing •-* 6 x aooo • 31,ooo 1422 to 2144 L> 32, t;; %6,. (.r.
----------~--------------------~------------------
mill tracking system by the furnace operator who is also re-
sponsible for insuring that the correct slab lo~ding sequence
is maintained.
The slabs are centered automatically at the furnace entry
door and pushed into the furnace vestibule such that they
are properly spaced within the furnace. The oil-fired fur-
nace, with provision for future natural gas operation, is de-
signed with control zones along the length and across the
width. This design, which includes level 2 furnace control
insures a controlled rate of heating and temperature distri-
bution for target temperature.
Extractors, initiated by the roughing mill operator, auto-
matically remove the slabs from the furnace and convey
them to the furnace discharge table where they are pro-
cessed through a hydraulic high-pressure descaling unit pri-
or to entering the roughing stand.
The descaling units consist of top and bottom sprays, to-
tally enclosed within a pivoting head to contain the spray.
Theyare activated to clean a slabon the first, third, fifth and
seventh passes. Specially designed header covers provide a
water-free environment when rolling stainless steel.
Roughing mill
The roughing stand with attached vertical edger is shown in
Fig. 2. It has provisions for future installation of hydraulic,
automatic width control cylinders and semiautomatic work
roll changing. The 4-h reversing rougher is powered by two
4500-hp motors that are directly connected to the work rolls
utilizing universal joint spindles. It is rated for a maximum
mill draft of 50 mm/pass for low carbon steel.
The mill is equipped with electromechanical screws with
roller thrust bearings and load cells for force measurement.
Work rolls are stack changed on top of the bottom backup
roll by a hydraulic pull-out unit that minimizes roll change
time by eliminating the need to disconnect the oil film bear-
ing supply-drain lines of the backup roll chocks.
November 1990

3. Fig. 3 - Coilbox and rotary
drum-type crop shear.
A width measuring gage, located at the delivery side of the
mill, is incorporated into the overall mill width control sys-
tem.
The vertical edger is powered by two 800-hp vertical
mounted motors with the roll gap adjusted by two 100-hp
verticallymounted motors. Maximum edging capacity is rat-
ed at 50 mm/pass on a 250-mm thick slab. Edger rolls are
changed with a specially designed C-hook during a semiau-
tomatic roll change sequence.
Coilbox
The transfer bar from the roughing stand is formed into a
coil at the Coilbox (Fig. 3). The Coilbox operates in conjunc-
tion with the roughing stand because approximately half of
the coil is formed before the tail end of the bar exits the
roughing stand.
The Coilbox design incorporates a transfer arm that per-
mits transfer of the coil to a No. 2 roll cradle position. On
transfer of the first coil, coiling of a second coil (from the
next rougher transfer bar) is initiated in a simultaneous op-
eration. The Coilbox also features bending rolls that are
mounted in a pivoting arm. This arm can be retracted to
facilitate roll changing. A delivery-side pinch roll assists in
threading the mill and cobble removal
The rotary drum-type crop shear (Fig. 3) features a quick-
change drum cassette design. Each drum contains two
Fig. 4 - Six all-hydraulic 4-h fin-
ishing mill stands.
November 1990
knives, one with a curved profile for head-end cropping and
the other with a straight profile for tail-end cropping. The
shear is powered by two 200/400-hp motors and is rated for
shearing up to 30-mm thick carbon steel transfer bars at
speeds of 100 metres/min. Laser units, located between the
Coilbox and shear, are used to detect the transfer bar and
initiate automatic crop cutting.
Finishing stands
The six, all-hydraulic, 4-h fmishing stands (Fig. 4) are each
powered by 6000-hp motors and are work roll driven through
gear-type spindles. Each stand includes long-stroke hydrau-
lic roll force cylinders located at the top of the mill window
with sufficient stroke to cover the full range of backup and
work roll turndown and maximum roll gap settings. Special
control algorithms are incorporated into the control system
to compensate for the long-stroke oil column effect.
Work roll bending for both crown-in and crown-out is pro-
vided at each stand and is utilized in conjunction with the
United ROLLFLEX computer program analysis for profil-
ing requirements. Work roll shifting is obtained with a side-
shifting stroke of ::1:75 mm.
Work rolls are positioned utilizing a servovalve control se-
quence based on a predetermined roll wear pattern to mini-
mize roll changes and maximize in-stand roll life.
Automatic, rapid, work roll changing is provided for si-
Iron and Steel Engineer 41

4. -
Fig. 5 - Finishing stands with zoned roll cooling headers. roll bite
oxide suppressant sprays and low-inertia direct~riven loopers.
multaneous changing of all six stands. Semiautomatic back-
up roll changing with hydraulic pull-out change rigs are pro-
vided at each stand. Six-stand simultaneous automatic roll
changing is accomplished within 6 min.
Each stand also includes zoned roll cooling headers, roll
·bite oxide suppressant sprays and low-inertia direct-driven
loopers (Fig. 5). Provisions have been made for the future
installation of a United patented looper-shapemeter at
stand F6 and United patented interstand Waterwall strip
cooling headers. Engineering for future installation of a con-
ventional oxide removal system is also provided. Width,
thickness and strip profile gages are located at the exit side ·
of stand F6 to monitor and control product quality parame-
ters of the strip.
Strip cooling
Strip is cooled on the runout table by a United patented top
and bottom Waterwall cooling system (Fig. 6). Each header
is designed for high/low flow on-off control with a variable
flow trim bank. The system is temperature controlled with
feedback from hot metal strip detectors located at the entry,
mid-section and delivery end of the cooling zones.
High-pressure side sweeps are included to minimize cool-
ant carry-over between headers and to clear the coolant from
the strip at the metal detectors. There is a recirculating strip
cooling water system complete with the coolant reservoir
which is integral with the table foundation. Due to the high
annual ambient temperatures in Kaohsiung, a separate cool-
ing tower is also provided to balance the recirculating cool-
ant water temperature.
Each header can be isolated for optimum selection of cool-
Fig. 6 - Runout table cooling system.
42 Iron and Steel Engineer
ing spray patterns. Header selection is determined from
temperature data and strip velocity to obtain required met-
allurgical properties of the strip.
Oowncoilers
Strip leaving the cooling section enters one of two hydraulic,
bumpless wrap downcoilers (Fig. 7). The coilers feature
wrapper roll full tracking of the coil throughout coil build-
up, porter bar wrapper roll changing, plug-in type double-
expand mandrel with automatic lubrication and cooling sys-
tem, and low inertia double-armature main drive motors
with disengaging clutch to isolate a single armature to pre-
vent necking of light gage strip.
A hydraulic traversing and lifting coil car with top-mount-
ed rollers is utilized for automatic coil tailout, spotting and
coil removal. The car is also fitted with a device to assist in
plug-in mandrel removal.
The dovmcoiler pinch roll unit features a pivot-mounted
top roll with automatic roll gap setting and a bottom pinch
roll passline adjustment mechanism for maintaining parallel
alignment of the roll and downcoiler mandrel.
Two hydraulic walking beam coil conveyors are utilized to
cool and transport the coils, with the eye in a horizontal posi-
tion, through an automatic coil banding and weighing sta-
tion. Coils are removed by either overhead crane or coil
transport vehicle, placed on an interbay coil transport sys-
tem and delivered into the coil storage buildings for further
coil processing and shipment.
Roll shop
The roll shop utilizes an interbay roll transport car to deliver
rolls into the main mill bay. Located in the roll shop are two
CNC work roll grinders and one CNC.combination work roll/
backup roll grinder. There is space for a future roll lathe and
work roll grinder. Work roll and backup roll bearing cleaning
stations, assembly areas, roll storage racks and spare parts
storage areas are also provided. Provisions for an automatic
work roll chock extractor and backup chock tilter are includ-
ed.
Project schedule
A fast-track construction project philosophy was developed
to maintain the proposed 27-month schedule from contract
signing to rolled coil production.
An elevated mill design was selected to minimize excava-
tion and construction costs, reduce construction overall
schedule, and provide better access to the roll shop and mill
maintenance areas.
A detailed construction schedule was developed to control
equipment engineering, equipment manufacture and con-
struction engineering as well as construction and installation
of equipment. The United scheduling department selected
the Primavera System Finest Hour as the schedule program
format for the detailed schedule. A construction philosophy
was employed that permitted initial construction work to ·
Fig. 7 - Hydraulic bumpless wrap downcoiler$.
November 1990

5. Furnaces
Fig. 8 - Partitioning of mill con-
trol: VE-vertical edger; RR-re-
versing rougher; W-width gage:
TW BOX
lJlJ
VE RR COIL 1 2 3 4 5 II ROT SPRAYS .'
8~ QQ OQ~~~~~~~@~~~T~gggg'----'1_1I _1I
1
---=--ij(3~~~~
X-x-ray gage; T-pyrometer; and
p-profile gage. ·
I
'FURNACE•
:AREA I
ROUGHING MILL
AREA
proceed during the equipment design stage and the develop-
ment of construction engineering for interconnecting piping
and electrical wiring to proceed in a later time frame.
The use of embedded conduit and pipe tunnels was mini-
mized, and open pipe chases and electrical tray design phi-
losophies were utilized.
Sequencing of equipment installation based on required
equipment deliveries as monitored by the project schedule
resulted in an efficient use of available on-site labor.
Part 11-Distributed control system
The distributed mill control system is partitioned by mill
area (Fig. 8) and by function within the mill areas to provide
responsive, independent operation critical for real-time per-
formance. It is an integrated configuration of computers,
controllers and drives linked by communication networks to
facilitate optimum exchange of data and control informa-
tion. The system architecture, illustrated in Fig. 9, consists
of the following main elements:
• Process control computer system comprising a super-
visory computer together with area and operator in-
terface computers (shaded area in Fig. 9).
• Area controllers.
• Drive control and communication networks.
Process control computer system
The process control computer system is composed ofone su-
pervisory DEC MicroVax 3600 computer, five DEC Micro-
Fig. 9 - Distributed control system.
FINISHING MILL AREA
Bander 0 0
Weigher0 0
: COlLER AREA
Vax II computers and three DEC MicroVax 3500 operator
interface computers. The computers are linked by two com-
plementary communication networks that provide real-time
response and high levels of integrity in transmission of data
and control information.
Supervisorycomputer - The supervisorycomputersup-
ports primary data input (PDI) storage, prefumace tracking,
production and engineering log generation, alarm process-
ing, and program generation and maintenance capability.
The PDI input system provides the slab yard office and slab
identification room operators with a screen-based system to
input new slab data, delete or modify existing slab data. Op-
erators in other areas of the mill have the ability to modify
certain elements ofPDI as it relates to their area of controL
Area computers - The five area process computers (fur-
nace, roughing mill/Coilbox, fmishing mill, downcoiler and
spare) combine with the supervisory computer to provide
mill automation including product tracking, process model-
ing, scheduling and reference distribution.
The furnace area computer tracks all slabs into and
through the walking beam furnaces with a reheat furnace
temperature control model that optimizes furnace operation
by controlling furnace zone temperature set points based on
furnace load, push rate and rougher target temperature.
The roughing mill and finishing mill area computers in-
clude tracking, process models, feedback and adaptive con-
trol and mill pacing. · .
The tracking programs control reference sendout and col-
lection of feedback data based on hot metal detectors, metal
in stand indications, table directions and operator actions.
These inputs trigger setups to be run, references to be sent
out, and feedback data to be gathered and analyzed.
The setup models generate the rolling schedule required
to achieve thickness, width and temperature targets. The
rolling schedule includes position references, mill speed and
draft compensation. A feedback program compares mea-
sured values against predicted values and adjusts verniers
for subsequent bar to bar feedback.
A Coilbox temperature model calculates the temperature
profile of the coiled transfer bar. These values are used by
the finishing mill setup and finishing mill temperature con-
trol models. The finishing mill temperature control model
uses mill speed to control strip temperature and to achieve
finishing mill exit temperature while minimizing head to tail
temperature gradients. A shape setup model determines
work roll bending forces and load distribution necessary to
achieve strip crown and flatness.
The coiler area computer programs include tracking,
coiler setup and the coiling temperature control model.
The coi1er tracking program tracks coils from the finishing
mill exit area to the coiler weigh scales. As each new head end
approaches the coilers, the coil setup program is called, ref-
erences are distributed and tracking screens updated. Coils
are removed from tracking after the weight reading or after
the coil has been rejected.
The coiler setup program generates coiler sideguide posi-
43

6. tions, mandrel bending torque, mandrel guidance tension,
pinch roll gap and wrapper roll gap.
The coiler temperature setup and control model deter-
mines the correct number and point of initiation of runout
table laminar spray headers and spray header flow to
achieve and maintain the target coiling temperature
throughout the body of the strip. Spray header flow is ad-
justable between discrete high and low settings. In-bar feed-
back control is provided to the vernier (last) spray bank
based on measured coiling temperature. Bar to bar adapta-
tion uses coiling temperature feedback to minimize coiling
temperature error.
Operator interface computers - The three operator in-
terface computers (furnace/roughing mill, finishing/coiler
and spare) support the screen displays, operator inputs and
alarm messages as well as off-line screen maintenance. The
overall operator interface system is discussed later in greater
detail.
Area controllers
The area controllers are GE Distributed Micro-Controllers
(DMC) which implement the drive level automation and
control functions. Included are drive master control, posi-
tion regulation, in-bar algorithmic control (eg, gagemeter
AGC) and sequence control. Control, process and device in-
put/output (1/0) are processed by the area controllers.
The furnace entry and furnace delivery DMC's are re-
sponsible for sequencing, pusher/extractor position regula-
tion. The furnace entry DMC also reads the slab weigh scale
and performs slab positioning, slab width and slab length
measurements. The furnace process DMC is the interface
between the furnace control and furnace optimization model
providing set points to the furnace control and obtaining
furnace process data, by zone, for feedback to the model.
The seven roughing mill, Coilbox and shear DMC's pro-
vide sequencing control, speed and position references, draft
compensation for speed references, and width gage inter-
face. A dynamic motor thermal model is implemented within
the roughing mill process DMC for real-time determination
of motor RMS load. The Coilbox DMC's provide dynamic
gap adjustment position references and head/tail tracking in
addition to the sequencing control.
There are a total of 19 fmishing mill DMC's that provide
distinct partitioning of functions with ample performance
margin to achieve the response necessary for hot mill opera-
tion. For example, each fmishing mill stand has two DMC's
(12 total) dedicated to the functions of hydraulic cylinder
control and eccentricity compensation, respectively, with a
common DMC providing the AGC function. The fmishing
mill main drive speed control DMC controls and coordinates
stands F1 to F6 main drive master speed references includ-
ing necessary compensations. The looper control DMC
maintains strip tension and interstand looper position while
the sideguide DMC provides closed-loop position regulation
ofthe stand sideguides. The fmishing mill process DMC uses
strip length accumulators to gather head and body perfor-
mance data on delivery gage, width and cro'III'D. These data
are sent to the fmishing mill area computer and supervisory
computer at strip tail-out for further analysis. (Finishing
and coiling temperature classification are performed sepa-
rately in the supervisory computer.)
The AGC and monitor DMC operate in either of two
modes: absolute AGC; or lock-on AGC. Absolute AGC uses
the setup references of thickness and predicted force and
applies the gagemeter equation to generate roll position ref-
erences to the hydraulic cylinder control DMC's. In the lock-
on mode, the gagemeter locks onto and regulates to delivery
thickness. The gagemeter monitor uses the exit x-ray gage
deviation signal to compensate for errors in strip thickness.
The monitor may operate in one of two modes: on; or lock-
on. In the on mode, it nulls the x-ray gage deviation error by
44 Iron and Steel Engineer
comparing the gage deviation error to the thickness refer-
ence and integrates the error during rolling of the bar. In
lock-on mode, it maintains strip thickness by locking onto
the head-end gage and integrates the gage deviation error
during rolling of the bar. Other features include surveillance
to monitor stand limits and screw fanning to move all hy-
draulic cylinders when head-end gage exceeds a dead band
value. Other compensation features include nonlinearity of
mill modulus, mill modulus by strip width, roll heating,
backup roll bearing oil film, tension loss, strip hardness and
load redistribution.
The six finishing mill hydraulic cylinder con~rol (HCC)
DMC's interface with the AGC system and provide hit:h-
speed in-bar positioning of hydraulic actuating cylinders.
Other functions include automatic zeroing and manual lev-
eling. Absolute displacement transducers and hydraulic
pressure transducers provide feedback.
The six roll eccentricity filtering DMC's monitor errors
introduced by backup roll eccentricity and proide filtering
to reduce strip thickness errors and maintain stability of the
AGC system.
A roll bending DMC controls strip shape using the work
roll bending cylinders between the work and backup rolls of
stands Fl through F6.
The roll shifting DMC shifts the work rolls to accomplish
schedule-free rolling. Automation schedules the shifting and
the DMC provides hydraulic position regulation to reposi-
tion the work rolls between bars.
The roll change DMC provides for the automatic prepara-
tion, extraction and reinsertion of new work rolls.
The four coiler area DMC's, including the runout table
spray's DMC, provide the control for the runout and coiler
areas. The runout table spray's DMC sets the flow rates for
spray headers and the three vernier banks based on inputs
from the coiler temperature control model or the operator.
The coiler master control DMC's coordinate and generate
the master speed references for No. 1 and 2 coiler drives and
tables based on head and tail tracking. The No. 1and 2 coiler
jump control DMC tracks the strip head-end through each
revolution of the roll using sensors located on each top pinch
roll. Hydraulic actuators on the wrapper rolls cause outward
motion of the wrapper rolls to minimize the force effects of
the head-end on innermost wraps.
Drive control and communication networks
Drive control - The d-e main drives, d-e auxiliary drives
and power conversion equipment are microprocessor based
with communication links with the DMC area controllers
(Fig. 10).
Comprehensive self-diagnostics, coupled with the ability
to tune and monitor by terminal, support timely start-up
and maintenance of the drive control.
The a-c auxiliary systems are conventional systems with
pump start/run/backup sequencing being implemented
within the three fluid system DMC's covering the a-c sys-
tems for the furnace/roughing mill, finishing mill and the
downcoilers. The furnace/roughing mill, finishing and
downcoiler fluids DMC's control the water sprays, lubrica-
tion oil and hydraulics systems.
Direct connections are made to the starter panels and
operator's display terminals.
The four area operator interface DMC's interface with the
direct action keyboards and the operator's discrete desk de-
vices.
Communication networks - These networks include the
Ethernet computer network and the GE control signal free-
way (CSF) network (Fig. 11).
Information transmitted over the Ethernet computer net-
work includes product data, DMC program source files and
data bases to support initialization ofthe backup computers.
The CSF is a peer to peer token passing network for high-
November 1990

7. _.......----
DC
DRIVE
CSF
BUS INTERFACE UNIT
C·BUS
.A:Ig. 10 - Drive control.
speed communication among the distributed control system
components. It is used for all high-speed control signals
while the Ethernet computer network is used for larger vol-
umes of data.
Also shown in Fig. 11 is the DMC low level connections to
operator I/0, process I/0 and the C-bus link to the Siltron
digital drive control.
Information flow is illustrated in greater detail in Fig. 12
which also shows the data classes transmitted during rolling.
As each slab is charged, its primary data input (PDI) is
transmitted over an Ethernet computer network from the
prefurnace tracking program in the supervisory computer to
the tracking program residing in the furnace area computer.
Each area computer subsequently sends the PDI and latest
slab process data to the next (downmill) area computer. This
data transfer occurs as the slab/coil progresses through the
mill and crosses tracking zone boundaries. The tracking
boundaries are furnace extract, rougher exit and finishing
mill exit. When the coil has completed the banding and
weighing process, the final coil data tables are sent to the
supervisory computer for logging and storage.
The setup models transmit references from the area com-
puters over the CSF to the DMC's, which then transmit over
the C-bus to the digital drives. These same references are
Jflg. 11 - Communication networl<s.
PROCESS CONTROL COMPUTER
SYSTEM
CONTROL SIGNAL
FREEWAY (CSF)
November 1990
OPERATOR INTERFACE
SYSTEM
OISPLAY
CONTROLLERS
ETHERNET
POl & MOOELS TABLES
ALARMS
CONTROL
SIGNAL
FREEWAY
(CSF)
PROGRAM
OOWNLOAO
--Fig. 12 - Data classes.
COILOATA
SCHEDULE &
ALARMS
GRANT t..IOOELS
ORIVE POSITIONS, SPEEDS
GAUGE FOBK's. ROLL FORCE. ALARMS
MOOES &
PRESETS REFERENCES
read by the operator interface system (OIS) computers to
display the setup information to the operators. The opera-
tor's inputs (eg, drive modes, presets, model granting and.
load distribution) are transmitted to the drives and comput-
ers over the CSF. During strip rolling, the gage, force, and
pyrometer readings are passed from the DMC's to the opera-
tor interface system and area computers over the CSF cable.
Operator Interface system
The operator interface system provides fully interactive op-
erator control through color-graphic CRT's and function
oriented direct action keyboards (DAK's). The operator in-
terface system provides a hierarchy of special purpose dis-
plays enabling the operators to monitor the mill, interface
with the process control system and setup drive control
functions. A flexible method of linking the displays provide
simplistic operation. VDU display changes are easily execut-
ed. Operator interface system computer equipment consists
of three DEC 3500 MicroVax computers.
The roughing mill pulpit arrangement (Fig. 13) shows the
operator interface equipment available to the roughing mill
operator. VDU's and keyboards have replaced most desk de-
vices. The discrete devices are limited to three E-stop push
buttons (circles in Fig. 13), the E-stop resets, rougher main
drive manual speed joystick and the edger speed vernier.
The extractor VDU normally displays the extractor over-
view screen that shows the packing gap time, pacing count-
down timer, a mimic of the first two slab rows on the dis-
charge end of the furnaces and mimics for the delivery table
hot metal detectors and the slab just extracted.
The extractor direct action keyboard (DAK) has prede-
fined keys for automatic or manual mode selection of the
furnace extractors and delivery tables. The extractor man-
ual commands include synchronized and individual east and
west extractor controls. In automatic mode, the operator is
limited to the accept (slab) to extract and the cancel accept
keys.
The roughing mill (RM) VDU terminal will normally have
Iron and Steel Engineer 45

8. .....MANUAL
SPllD
•o
IJTIIACTOR
"""
ffi±±Hf8If9
Fig. 13 - Roughing mill pulpit.
SP'EEO
OAK
AUX
OAK
IAK
TRACK
....
ALARM SCREEN
PAINTER PAINTER
SETUI'
vou
the production overview screen displayed. This screen com-
bines tracking zones with a mimic ofstands and mill sensors
to provide strip in stand and strip under sensor indications.
The three tracking zones shown are next to extract, furnace
delivery, roughing mill and Coilbox. Slab !D's are shown for
all zones.
The setup VDU will normally have the model setup calcu-
lations screen selected. This screen presents the rougher
stand and edger schedule. Up to nine passes of screw posi-
tion, descale practice, horizontal stand draft, force, speed,
sideguides, edger draft and edger references are displayed.
Incoming transfer bar finishing dimensions and tempera-
tures are also provided.
The interactive keyboard (IAK) and the trackball in front
of the setup screen are typical of all mill pulpits. The key-
board (IAK) is used for displayselection for each ofthe three
roughing mill VDU's, screen cursor movement, alphanumer-
ic screen data entry, alarm acknowledgment and drive mode
selection. Use of the trackball is an alternative method for
screen cursor movement. To the rear of the operator are two
printers. The alarm logger will print all roughing mill area
alarms of interest to the operator. The screen printer can be
used by the operator for a hard copy printout of any rough-
ing mill VDU screen.
A drive level diagnostic panel, mounted on the front of the
drive control and power conversion package, displays micro-
processor driven LED's arranged functionally to indicate
motor faults, converter faults and drive status. Conventional
setup and annunciator panels located within the electrical
rooms provide centralized local fault monitoring. Drive an-
nunciations and faults (detected by the DMC's) and process
alarms (detected by the area computers) are transferred to
the supervisory computer for alarm logging.
The operator interface system automation level alarms
and diagnostics system is a system-wide automation func-
tion. It provides all mill operators with VDU alarm messages
and alarm printouts identifying abnormal operating condi-
tions. Three different alarm types (severe, error and infor-
mational) are supported and color coded for ease of compre-
hension. Alarms can originate from any DMC or computer.
Redundancy is provided in the critical areas of the control
'48 Iron and Steel Engineer
.-------
r---
CSF •1 CABLE B
REPEATER
·------------
FURN/ RM
AREA &
OIS
COMP's
CSF A CABLE
-----,
FM/
COlLER
AREA &
015
COMP"s
COIL BOX
&SHEAR
OMC's
. I
~--------------------
CSF 112 CABLE B
REPEATER
: : ~ - - r:::--1---_j
I - - - -
I
-------
Fig. 14 - Redundant control signal freeway (CSF) system.
signal freeway (CSF}, area process computers and operator
interface computers. The CSF is installed with two cables
(Fig. 14) between each (computer or DMC) CSF station. The
system will automatically detect a break in either CSF cable
and reconfigure to use the backup cable without manual in-
tervention. A spare operator interface system computer and
.a spare area process computer can be initialized to perform
the functions of any of the process computers.
Summary
The 1675-mm (66-in.), 2 million tonne/year semicontinuous
hot strip mill for An Feng Steel Co., Taiwan, has been de-
scribed. Designed toroll1000-piw,l.2 to 12.7-mm thick mild
steel, high-carbon low-alloy and stainless steel products, it
basically consists of:
• Two walking beam, 250-tonne/hr, slab reheat fur-
naces.
• One reversing rougher with attached edger.
• One Coilbox.
• Six 4-h, all-hydraulic finishing stands.
• Two hydraulic downcoilers.
• Two walking beam coil conveyors.
Also reviewed are production levels and performance tar-
get criteria.
Ahierarchical distributed control system is employed that
comprises the following main elements: process control com-
puter system consisting of a supervisory computer with area
and operator interface computers; area controllers; and
drive and communication networks.
The mill is scheduled to be commissioned in Nov. 1990. A
November 1990