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Scheduling of Rolls for Production Campaigns in both Cold Mills
and Hot Mills
Khalil
Fazlollahi, Ph.D. M.Sc. B.Sc. P.Eng, Quad Infotech Inc., Toronto,
ON Canada
Tony D’Antonio, Roll Shop Manager, Worthington Steel, Decatur,
AL, USA
Guy Pilon, Project Manager, Quad Infotech Inc., Toronto, ON Canada
Hooman Fazlollahi, B.Sc. Senior Analyst programmer, Quad Infotech
Inc., Toronto, ON Canada
Background
Quad Infotech has developed a family of software modules for shaped
steel plant operations called “Quad Mill Operation System”
[QMOS]. This product deals with Production scheduling and reporting,
rolls scheduling for a production campaign, and management of
the roll and setup shops. [QMOS] has been operating in a number
of reputable steel plants throughout the United States, Canada
and Europe, since 1992.
The
main modules that comprise [QMOS] are
- [QMOS]PSC
Production Scheduling and Control
- [QMOS]RSP
Roll Shop Planner (Management), including Guide Shop
- [QMOS]STP
Production Monitoring and Shift Reporting
For the past
three years, Quad has been working with flat rolling mills to
develop FLAT version of [QMOS] to address their unique needs of
Hot and Cold Flat rolling mills
[QMOS]Flat
has been successfully implemented at Worthington Steel in Decatur,
AL. This tool is designed to schedule and drive roll shop activity,
to record mill performance, to help the operators make decisions
during the shift, and to help managers perform analysis and view
trends allowing for consistent improvement to the processes.
[QMOS]Flat
provides the following main functions
- maintain
roll Inventory,
- prepare
rolls,
- create
roll schedules,
- assemble
roll sets,
- move rolls
to production,
- disassemble
rolls,
- maintain
roll components.
In order to
justify this project, the roll shop management system was expected
to provide the following beneficial effects:
- Minimize
investment in roll and roll related inventory. Increase roll
life;
- Improve
the quality of the rolled product by utilizing more accurate
roll results from the grinders;
- Increase
mill productivity, (by decreasing mill change-outs), from roll
shop scheduling improvements.
Maintain
Roll Inventory
Working with engineering and the roll vendors, roll shop management
plans and executes roll procurements. Not only are inventory levels
of rolls involved, but so are the chemical and physical specifications.
Through analysis of roll performance, procurement decisions are
made with an eye toward minimizing roll investment through increased
roll life longevity.
[QMOS] supports
this function by providing production and grinding performance
histories for each roll and the ability to display this information
in ways that illustrate trends and suggest root causes.
Prepare
Rolls
In this process, the surface of the rolls are prepared, (ground,
textured, and chromed), when they are received as new inventory,
and each time they are changed out of the mill.
Measurement
results from these operations, (crown, roughness, diameters, etc.),
are automatically captured by [QMOS] for later procurement analysis
and automatic communication to the mill.
Create
Roll Schedules
In response to mill production schedules, roll schedules are created
to plan roll assembly and staging.
This activity
is supported by [QMOS] by bringing together the mill production
schedule and roll inventory information into one place for roll
schedule creation.
Assemble
Roll Sets
Work rolls and backup rolls must be assembled into sets, (two
rolls plus chocks, bearings, and seals), before they can be used
in the mill.
These assemblies
are recorded into the [QMOS] system for use by roll shop personnel
to keep track of what is ready for production, and the mill software
to easily identify what is being loaded into the mill.
Move
Rolls To Production
After assembly, rolls are moved to staging areas as they proceed
to the mill.
Each time
that a roll is moved, its new location is recorded in [QMOS].
When a mill queries [QMOS] about a work roll or backup roll set
about to be loaded into the mill, the roll shop system automatically
supplies the necessary identity and measurement data needed by
the mill.
Disassemble
Rolls
After the completion of a run for each roll, the rolls are changed
out of the mill, and disassembled in preparation for the supporting
roll components, (chocks, bearings, and seals), to be maintained,
and the rolls’ surfaces to be ground.
As the rolls
are changed out, the mill system automatically sends production
information to [QMOS] for inclusion in its roll history.
Maintain
Roll Components
The individual parts of the roll assemblies and sets are inspected.
At this point, items are replaced and bearings rotated where necessary.
The accumulated
production history of bearings in the [QMOS] database is used
to assist in the rotation process. The disassembly of the roll
assemblies is reflected in [QMOS] to maintain an up-to-date record
of the location and status of the components. This can also be
scheduled.
[QMOS]Flat
Roll Shop
Roll Grinding activity is automatically scheduled based on mill
activity. When rolls are removed from the mill and de-chocked,
the next step in the usual process is to grind the rolls so that
they are ready to use the next time that they are required. When
the operator records that chocks have been removed from the rolls,
he is given the option to automatically create a roll grinding
work order. The rolls will then be scheduled for roll grinding
at the next available time.
Similarly,
rolls can be scheduled for grinding based on when they are next
planned for use in the mill. The roll grinding schedule is calculated
to allow sufficient lead time to complete the process in time
to have the rolls chocked and ready for the mill before they will
be required.
A
list of standard procedures or steps required to grind each roll
is accessible, providing an instant “how to” manual
for all shop personnel. Users can track which steps have been
completed, so that the supervisor and other workers all know the
current status of the job. This feature also provides a list of
SOP’s which then conform to ISO standards.
Some shops’
roll grinding procedures include external processes for things
such as chroming and for other finishing processes or repairs.
[QMOS] handles all of this seamlessly. Each roll may be sent to
any number of vendors for a variety of reasons. Results from each
process can be recorded, including the external cost and the quality
of the work done. The whereabouts of each roll is always known,
as well as the status of each roll for each step in the roll grinding
process.
When a roll
is finished being ground, new roll diameters and roll surface
readings are recorded in [QMOS]. Any roll which is ground more
or less than expected is flagged, requiring the operator to acknowledge
and explain what has happened. Hardness readings can be noted,
and saved for further analysis. Information on sub-surface conditions
such as cracks and bruises can also be stored. The grinder operator
responsible for grinding the roll is saved. A full historical
profile of each roll is saved, detailing all roll grinding results
and suitable for investigation and historical analysis.
Grind Wheel
performance is tracked by recording specific activity and use
of each grind wheel. The amount of wear on the wheel, and the
number of rolls ground and the total amount ground off all rolls
are all attributable back to each individual grind wheel. Detailed
reports are available depicting grind wheel inventory and performance
and can be tracked by vendor.
Roll
Scheduling
Rolls are scheduled for the mill based on roll availability and
the upcoming production schedule. The best Work Rolls and Backup
Rolls are recommended at each stand, based upon the crown and
texture required in each stand. Roll changes must take place whenever
the rolls in the mill are not appropriate for the upcoming production,
or when they are worn. [QMOS] is able to compare the expected
usage on the current rolls with the upcoming rolling, The system
will suggest that the rolls be changed based upon comparisons
with historical data concerning the usual amount of use by similar
rolls when they wear out. The operator is given a view of the
whole mill cross referenced with upcoming production, providing
the easiest and most efficient means of roll scheduling.
The coil width
being used is also considered, in order to prevent marking or
scoring on the finished product. [QMOS] checks for the expected
finished product width to determine if the rolls might cause a
problem due to a change in coil width.
Roll
Inventory
All roll purchasing, scrapping, and depreciation is handled by
[QMOS]. Worn or broken rolls which need to be scrapped, and [QMOS]
records details of the roll status, and removes the rolls from
the active roll inventory.
As rolls wear
or break, and they are due to be replaced, [QMOS] prepares the
necessary Purchase Order for ordering the replacement rolls. When
new rolls are received and accepted, they are then added to active
roll inventory and can be used in the mill.
When the roll diameter is reduced due to roll grinding, [QMOS]
automatically depreciates roll values accordingly. An end of month
Account Summary is produced which shows opening and closing roll
inventory balances, as well as the details of roll consumption
during the month.
Many other
reports are available, including those which illustrate roll performance
by supplier, or by roll material, and activity of the roll shop
for a period of time or for a specific grinder operator.
Stand
Building & Tear Down
Once rolls have been ground and are ready for use, they must be
chocked and built into the correct stand. Stand Building activity
is scheduled and tracked through the Bearing & Chock Inventory
module. [QMOS] tracks which chocks and bearings were used on each
roll, and who did the work. Rolls can be built up for a specific
stand for upcoming production, or as a spare in case of premature
roll wear or breakage.
Later, when
the rolls come out of the mill, they are de-chocked. The operator
records this activity, which then breaks the relationship between
the rolls and the chocks. When this is done, the operator is given
the option to automatically create a roll grinding work order,
beginning the entire process again.
A list of
standard procedures or steps required to build and tear down each
stand is accessible, providing an instant “how to”
manual for all shop personnel. Users can track which steps have
been completed, so that the supervisor and other workers all know
the current status of the job. This feature also provides a list
of SOP’s which then conform to ISO standards.
Bearing
& Chock Inspection
Bearing and Chock inspections carried out periodically enable
the setup shop to track various measurements, such as bearing
bore and chock width across liners. When the bearing is assembled
into the chock, the load zone used is recorded, as well as the
employee who performed the inspection. Also any chock parts, seals
and assorted hardware can be recorded on the work order. This
can also be used for historical data tracking.
Again, a list of standard procedures or steps required to inspect
bearings and chocks is accessible, which provides a manual for
all shop personnel. This provides a list of SOP’s which
then conform to ISO standards.
Interfaces
A number of
interactive processes between [QMOS] and other systems and equipment
have been automated at Worthington Steel, including roll grinders
and the mill operation system.
Roll
Grinding Interface
Worthington uses two Waldrich-Seigen grinders in the roll shop.
As roll grinding takes place, a user-friendly interface allows
grinding results to be automatically transferred from the grinders
directly to [QMOS]. A complete roll diameter profile is captured,
along with Eddy Current crack and bruise data. The only user intervention
required is to ensure that the correct roll number is entered.
This interface
allows complete accuracy for recording roll grinding results,
and occurs instantaneously upon completion of the roll grinding
process.
Mill
System
When the mill system calls for new rolls for any stand, roll diameters
are passed from [QMOS], along with other roll information required
for mill setup. The mill system operator does not need to manually
enter any further roll data in order to set up the mill to run.
As coils are
produced, the tonnage and length of steel produced are immediately
passed back to [QMOS]. [QMOS] then keeps track of the amount of
steel rolled by each work roll and backup roll each time it is
used in the mill. Tonnage and length rolled is stored for each
roll over its entire life, and since it was last ground. This
data provides meaningful analysis of roll usage and performance.
The roll tonnage
is also applied directly to the chocks and bearings used with
each roll. Bearing and Chock maintenance and inspection schedules
can be set up based on their usage, to try to prevent or limit
bearing failure. Tonnage is stored for each chock and bearing
over its entire life, and since the last inspection.
When rolls
are changed in the mill, [QMOS] is immediately notified. The tons
and length rolled stop accumulating on the rolls, and begin to
accrue to the new rolls, chocks, and bearings. A work order to
tear down the stand is automatically created.
Analytical
Power of [QMOS]
The tonnage
and length of steel produced that are passed back to [QMOS] as
coils are produced provides data for meaningful analysis of roll
usage and performance. Reports showing roll cost per ton can be
printed for whichever rolls or time period required.
A Roll History
Report can be used to spot interesting results and trends in terms
of roll wear or roll value when generated by supplier or by roll
material. Reports detailing the performance and usage of grind
wheels, or grind wheel suppliers, can also be prepared and measured
in the same fashion.
A periodical
Roll Grinding Report will show overall roll grinding activity.
It can also be produced for a particular lathe operator, which
is useful to identify the need for additional training or a possible
change required to standard procedures.
From the historical
roll profile, it’s possible to review and graph roll hardness
as the roll wears. This has proven particularly useful when analyzing
the causes of roll breakage. Production of the Roll Hardness Profile
has become a part of standard routines whenever a roll breaks
or wears prematurely.
Summary
The [QMOS]FLAT Roll Shop Management System is a client server
application runs on Windows family of products. Oracle is used
as the data base management system using UNIX, or NT platform.
This System is currently used by Worthington Steel, Decatur AL
for planning roll shop events, monitoring shop activity, helping
operators make decisions during the shift, and for performing
analysis and viewing trends to allow for consistent improvement
to the processes.
The system
has provided improved roll shop efficiency which has lead to a
reduced investment in roll and roll related inventory, and increased
roll life. The quality of the finished rolled product has improved
by utilizing more accurate roll results from the grinders. There
is now an increase in mill productivity, directly resulting from
roll shop scheduling improvements.
About
Quad Infotech
Quad Infotech
Inc. is a Software Engineering and Design company specializes
in the development of computer software for the steel industry.
Quad’s unique combination of steel rolling mill and melt
shop process knowledge combined with computer software design
expertise makes Quad’s Software Products leader in the World
Wide Steel Industry.
The family
of software modules Quad Infotech has developed for steel plant
operations is called the “Quad Mill Operation System”
[QMOS].
[QMOS] is
implemented as a full service product including site assessment,
information analysis, data conversion, site training, This product
is currently operating in a number of steel plants throughout
Canada and the United States.
[QMOS]
Modules:
Oracle
DB
[QMOS]
Modules:
- [RSP]:
Roll Shop Planner
- [GSP]:
Guide Shop Planner
- [BCI]:
Bearing and Chock
- [SBI]:
Saw Blade Shear Blade
- [PRR]:
Production Reporting
- [STP]:
Shift Planner
- [BTC]:
Bundle Tag Control
- [PSC]:
Production Scheduling
- [BYM]:
Billet Yard Management
- [MSC]:
Melt Shop Scheduling
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