Timken METALS INDUSTRY EDITION User Manual
METALS INDUSTRY EDITION
TIMKEN ENGINEERING MANUAL
TIMKEN ENGINEERING MANUAL
TIMKEN ENGINEERING MANUAL -
METALS INDUSTRY EDITION
INDEX
TIMKEN OVERVIEW.................................................................................2
Shelf Life Policy ................................................................................... 8
Storage .................................................................................................9
LUBRICATION AND SEALING ..............................................................95
Lubrication ..............................................................................................96
Lubrication Fundamentals ............................................................... 96
Main Lubricant Characteristics ...................................................... 99
Lubrication Selection .....................................................................100
Sealing ................................................................................................... 110
Sealing Types ...................................................................................110
Sealing Systems .............................................................................. 112
POPULAR BEARING TYPES IN THE METAL INDUSTRY .................. 11
Steelmaking ............................................................................................12
Continuous Casting ................................................................................ 13
Rolling Mill Stands ................................................................................. 14
Radial Bearings ................................................................................. 14
Thrust Bearings ................................................................................. 16
Auxiliary Equipment ............................................................................... 18
APPLICATION CONSIDERATIONS AND BEARING SELECTION ..... 21
Steelmaking ............................................................................................22
Continuous Casting ................................................................................ 27
Rolling Mill...............................................................................................33
Flat Product Rolling...........................................................................33
Long Product Rolling ........................................................................35
Bearing Solutions: Radial Positions .................................................... 36
Work and Intermediate Rolls: Flat Product Mills .........................36
Work Rolls: Long Product Mills ......................................................43
Backup Rolls ...................................................................................... 46
Bearing Solutions: Axial Positions ...................................................... 53
Auxiliary Equipment ............................................................................... 58
Main Mill Drive and Pinion Stand Gearboxes .............................. 58
Pay-off and Rewind Reels ............................................................... 60
Shears and Shear Drives ................................................................. 62
Table Rolls .......................................................................................... 64
BEARING LIFE CALCULATIONS AND RELATED ANALYSIS ............ 67
Summary of Symbols ............................................................................. 68
Fatigue Life .............................................................................................. 69
Bearing Ratings ...................................................................................... 69
Applied Loads ......................................................................................... 72
Bearing Life Equations .......................................................................... 81
Bearing Internal Clearance .................................................................. 86
Advanced Analysis ................................................................................ 92
APPLICATION CHALLENGES AND ENHANCED
BEARING SOLUTIONS.........................................................................115
High-Performance Bearings .............................................................. 116
Contact Fatigue ....................................................................................117
Debris ..................................................................................................... 120
Lubrication ............................................................................................122
Corrosion ............................................................................................... 124
Precision Rolling ..................................................................................126
High Acceleration ................................................................................ 127
RELATED PRODUCTS...........................................................................129
Seals and Lubricant ............................................................................. 130
Maintenance Tools .............................................................................. 131
Condition Monitoring Equipment ....................................................... 133
®
Timken
Timken Quick-Flex
Precision Chain Products ................................................................... 140
BEARING STORAGE, HANDLING AND INSTALLATION ................143
Bearing Packaging and Storage ....................................................... 144
Bearing Marking ..................................................................................144
Roll Neck Maintenance Guidelines .................................................. 147
Chock and Roll Neck Maintenance Guidelines .............................. 151
Mounting and Dismounting Roll Neck Bearings ............................157
Bearing Setting Techniques ............................................................... 168
SERVICES ..............................................................................................175
Gearbox Repair.....................................................................................176
Bearing Reconditioning and Reclamation ....................................... 177
Chock and Roll Upgrades ................................................................... 180
MILLTEC™ Rolling Mill Program ........................................................182
Service Engineering ............................................................................182
Training .................................................................................................. 182
Housed Units ........................................................................ 134
®
Couplings .......................................................... 138
TIMKEN ENGINEERING MANUAL
1
TIMKEN
GROW STRONGER WITH TIMKEN
GROW STRONGER WITH TIMKEN
Every day, people around the world count on the strength
of Timken. Our expertise in metallurgy, friction management
and mechanical power transmission helps them accelerate
improvements in productivity and uptime.
We supply products and services that can help keep your
operations moving forward, whether you need drive train kits
for commercial vehicles, durable housings for bearings in dirty
environments, couplings that avoid metal-to-metal contact
between motors and gearboxes, repair services for bearings
and gearboxes, roller chain for dry, abrasive and high-moisture
applications, steel for an aircraft engine shaft, or other
products or services for your applications.
When you choose Timken, you receive more than high-quality
products and services: you gain a worldwide team of highly
trained and experienced Timken people committed to working
collaboratively with you to improve your business.
Globally, our 20,000 people provide reliable answers for a
wide range of operations in manufacturing, mining, medical
equipment, aerospace, transportation, oil and gas – and other
diverse industries.
TIMKEN ENGINEERING MANUAL
2
INCREASE YOUR EQUIPMENT
UPTIME
In addition to high-quality bearings and mechanical power
transmission components, we provide valuable integrated
products and services. For example, we offer repair services
and equipment monitoring equipment that can alert you to
problems before they impact your uptime.
Additionally, we offer a broad selection of seals, premium
lubricants, lubricators, couplings and chain to keep your
TIMKEN
INCREASE YOUR EQUIPMENT UPTIME
operations moving smoothly.
Our technology centers in the United States, Europe and
Asia help pioneer tomorrow’s innovations with extensive
basic and applied scientific research programs. Through
internal development and strategic acquisition of innovative
companies, we continue to expand our portfolio of highly
engineered bearings and components.
TIMKEN ENGINEERING MANUAL
3
TIMKEN
METALS INNOVATOR
METALS INNOVATOR
Today, metal processing equipment handles heavier loads,
faster speeds and greater output than ever before. Finished
product quality requirements increase, while across the
industry manufacturers continue to place a very high premium
on equipment uptime and performance.
As the leader in friction-management and power-transmission
solutions for the metals industry, Timken helps metals operators
improve their equipment’s performance and uptime. We
accomplish this by providing custom solutions – from bearings
that can stand up to harsh environments to condition monitoring
that helps minimize maintenance costs and improve
plant productivity.
We have more than a century of experience developing
bearings and related solutions that help equipment run
more efficiently in a wide range of applications, including
steelmaking, continuous casting and rolling both flat and long
products.
INNOVATION AND
CUSTOMER SUPPORT
Timken operates technology centers around the world
dedicated to developing innovative concepts and products that
help you operate more efficiently. Our technical leadership and
customer support reaches far beyond our products. Timken
customers have access to sales and service engineering
support at their plants and options for additional support from
application engineers, who specialize in the metals industry.
CORE CAPABILITIES
Timken has evolved from its early roots as a bearing and
steel producer to a supplier offering much more, including
friction-management and power-transmission solutions that
add value throughout the complete life cycle of a system. Our
material enhancements improve bearing life and can protect
against debris and corrosion – two common challenges in
processing metals. Our precision manufacturing capabilities
and commitment to quality ensure global consistency in
design and manufacturing at every Timken facility. A global
distribution network provides our customers with easy access
to Timken products and services throughout the world.
We leverage these core capabilities as we work with
original equipment manufacturers (OEM) and designers
to integrate our technologies into equipment so that end
users can enjoy the performance benefits of Timken
products from the first day of operation. OEMs depend
on Timken for our engineering expertise, manufacturing
capabilities and emphasis on reliable performance.
TIMKEN ENGINEERING MANUAL
4
PRODUCTS AND SERVICES
We offer equipment builders and operators one of the most
extensive friction-management product and service portfolios
in the industry.
BEARINGS
We provide a broad range of bearing designs and
configurations for use in steelmaking vessels, caster segments,
work rolls, backup rolls, screwdown systems, mill drives,
pinion stands, coilers, table rolls, and auxiliary equipment.
Bearing types include:
Tapered roller bearings – Tapered roller bearings are
•
uniquely designed to manage both thrust and radial loads
and are available in single- and multi-row designs with a
wide range of assembly options. Our extensive offering
of tapered roller bearing combinations offers equipment
builders and operators simple, reliable and less costly
design solutions.
Cylindrical roller bearings –This design generally offers
•
the highest possible radial load capacity for a given size
compared to other roller bearing types. One row and two
row cylindrical roller bearings are ideal for many mill stand,
gear drive and other auxiliary equipment applications,
while four row cylindrical roller bearings are used in roll
neck applications. Timken offers both single and multi-row
cylindrical roller bearing. Custom designs are available
upon request for specific applications.
TIMKEN
PRODUCTS AND SERVICES
Thrust roller bearings – Thrust roller bearings for rolling
•
mill applications are available in cylindrical, spherical and
tapered designs. Thrust bearings are ideal for applications
experiencing heavy axial loads, such as mill stands,
screwdown systems and piercing mills.
Ball bearings – Ball bearings are used extensively in
•
auxiliary applications that have light loads and/or high
speed conditions. Timken offers a range of radial, thrust
and angular-contact ball bearings in both metric and inch
sizes. Please contact your Timken engineer for detailed
information on these product ranges.
Housed units – Timken® spherical roller bearing solid-
•
block housed units possess a unique cast-steel design
that handles demanding conditions in metal industry
applications. These solid-block housed units come in
several styles and five advanced locking configurations.
Timken spherical roller bearing solid-block housed units
are designed for challenging circumstances. A full line of
primary seals, covers and housings is available to find the
right roller housed unit to fit your application. In case of
high thrust loads, in excess of the spherical roller bearing
carrying capabilities, the Timken
Timken also provides a broad range of split-block housings
in both metric and inch sizes.
®
Type E is your solution.
Spherical roller bearings – Spherical roller bearings offer
•
high radial and moderate thrust capacity together with
maximum static and dynamic misalignment capability.
Timken spherical roller bearings provide high-static load
capacity and advanced geometry that reduces friction and
heat generation. These bearings are available in a range
of dimensionally stabilized configurations to suit elevated
operating temperatures.
TIMKEN ENGINEERING MANUAL
5
TIMKEN
PRODUCTS AND SERVICES
HIGH-PERFORMANCE BEARING
SOLUTIONS
Timken provides the metals industry with a variety of
high-performance bearing solutions, including Timken
AquaSpexx
corrosion protection. Our debris-resistant bearings are ideal
for contaminated and/or marginal lubrication conditions.
We also provide customized bearing solutions such as special
race profiles to meet special application requirements.
In addition to component geometry and metallurgy, we find
many ways to enhance bearing performance by applying
unique surface finishes and special coatings on rollers,
raceways and other functional surfaces. Engineered surfaces
and topographical modification reduce surface roughness
to lower levels than can be achieved through conventional
grinding and honing methods. We also offer proprietary
coatings that can create a surface up to four times harder than
steel with twice the elasticity. For more information on Timken
high-performance bearings and engineered surfaces, see
the Application Challenges and Enhanced Bearing Solutions
section of this manual (pages 115-127).
®
, DuraSpexx® and thin dense chrome bearings for
®
Timken manufactures precision roller
chain that are designed to meet
demanding steel industry applications.
We build chains to precise specifications
for strength and maximum wear life. The
offering includes a complete line of roller
chain, attachment chain and engineered
conveyor chain.
POWER TRANSMISSION
COMPONENTS AND SYSTEMS
Timken offers an expanding range of power transmission
components including seals, couplings and engineered chain.
Extreme temperatures and high contamination levels can
disable your equipment and significantly lower productivity.
Timken develops seals using advanced material and process
solutions that help protect machinery and minimize plant
downtime. We offer a comprehensive line of large-bore oil and
grease seals and metallic and non-metallic bearing isolators.
®
Timken
minimal maintenance. They are easy to install and require no
lubrication. These couplings are designed to connect motors
and gearboxes with other moving equipment with capacity to
transmit the same or more torque than a gear coupling with
the same dimensions. The Quick-Flex coupling's innovative
design utilizes an advanced elastomeric element to transmit
the torque and therefore eliminates any interference between
coupling hubs that can damage equipment.
Quick-Flex® couplings are highly durable, yet need
LUBRICATION
Timken lubricants reduce friction, reduce wear and protect
bearing surfaces from corrosion. We offer a wide selection of
lubricants, including Timken Mill Grease, which we formulated
to perform in the difficult roll neck bearing environment. Timken
single- and multi-point lubricators and lubrication delivery
devices help mill maintenance professionals simplify their
lubrication practices, saving time and money.
TIMKEN ENGINEERING MANUAL
6
CONDITION MONITORING DEVICES
Powerful diagnostic tools from Timken are designed to detect
potential bearing failure before it occurs. A variety of handheld
devices and online options – including our ultra-accurate
Online Intelligence System – let you monitor bearing condition,
lubrication quality and machine vibration (either periodically
or continuously) for increased productivity, safety and peace
of mind.
MAINTENANCE TOOLS
Timken maintenance tools may extend bearing life by
facilitating proper installation, removal and service.
They also help simplify maintenance practices.
We provide induction heaters, impact fitting tools
and hydraulic and mechanical pullers.
TIMKEN
PRODUCTS AND SERVICES
SERVICES
Used bearings and related components often can be returned
to their original specifications with less time and costs than
purchasing new. We offer complete remanufacture and
reconditioning services for many components, including
bearings, chocks, housings, rolls and more.
Our gearbox repair services are globally recognized as experts
in power transmission solutions for heavy industrial markets,
repairing virtually any large gearbox make or model, with
onsite emergency breakdown service available if needed.
Timken offers a full range of maintenance and reconditioning
services through our remanufacturing and repair operations.
Using these services can lead to improved plant efficiency and
reduced overall production costs.
Beyond bearing repair and depending on the location, we offer
chock maintenance and roll rebuilding to help mill operators
get the most out of their chock/bearing assembly.
In addition, our MILLTEC
around-the-clock management of the roll shop with the goal of
minimizing operational costs and downtime.
®
rolling mill program provides
TRAINING
We offer industry-specific training programs designed for plant
professionals, as well as on-site customized training to meet
your specific needs. Our metals industry training programs
are available at select locations around the world and cover
every phase of bearing performance in the metal-making
environment. Class time is balanced with extensive hands-on
training and tours of Timken facilities.
TIMKEN ENGINEERING MANUAL
7
TIMKEN
HOW TO USE THIS CATALOG • SHELF LIFE AND STORAGE OF GREASE-LUBRICATED BEARINGS AND COMPONENTS
HOW TO USE THIS CATALOG
We designed this catalog to help you find the bearings best
suited to your specifications.
Timken offers an extensive range of bearings and accessories
in both imperial and metric sizes. For your convenience, size
ranges are indicated in millimeters and inches. Contact your
Timken sales engineer to learn more about our complete line
for the special needs of your application.
This publication contains dimensions, tolerances and load
ratings, as well as engineering sections describing fitting
practices for shafts and housings, internal clearances,
materials and other bearing features. It provides valuable
assistance in the initial consideration of the type and
characteristics of the bearings that may best suit your
particular needs.
ISO and ANSI/ABMA, as used in this publication, refer to
the International Organization for Standardization and the
American National Standards Institute/American Bearing
Manufacturers Association.
Updates are made periodically to this catalog. Visit www.
timken.com for the most recent version of the Timken Metals
Engineering Catalog.
DISCLAIMER
This catalog is provided solely to give you analysis tools
and data to assist you in your product selection. Product
performance is affected by many factors beyond the control
of Timken. Therefore, you must validate the suitability and
feasibility of all product selections.
SHELF LIFE AND STORAGE OF
GREASE-LUBRICATED BEARINGS
AND COMPONENTS
To help you get the most value from our products, Timken
provides guidelines for the shelf life of grease-lubricated
ball and roller bearings, components and assemblies. Shelf
life information is based on Timken and industry test data
and experience.
SHELF LIFE POLICY
Shelf life should be distinguished from lubricated bearing/
component design life as follows:
Shelf life of the grease-lubricated bearing/component
represents the period of time prior to use or installation.
The shelf life is a portion of the anticipated aggregate design
life. It is impossible to accurately predict design life due to
variations in lubricant bleed rates, oil migration, operating
conditions, installation conditions, temperature, humidity and
extended storage.
Shelf life values, available from Timken, represent a maximum
limit and assume adherence to the storage and handling
guidelines suggested in this catalog or by a Timken associate.
Deviations from the Timken storage and handling guidelines
may reduce shelf life. Any specification or operating practice
that defines a shorter shelf life should be used.
Timken cannot anticipate the performance of the grease
lubricant after the bearing or component is installed or placed
in service.
Timken products are sold subject to Timken terms and
conditions of sale, which include our limited warranty and
remedy. You can find these at http://www.timken.com/en-us/
purchase/Pages/TermsandConditionsofSale.aspx
Please consult with your Timken engineer for more information
and assistance.
Every reasonable effort has been made to ensure the accuracy
of the information in this writing, but no liability is accepted for
errors, omissions or for any other reason.
TIMKEN ENGINEERING MANUAL
8
TIMKEN IS NOT RESPONSIBLE FOR THE
SHELF LIFE OF ANY BEARING/COMPONENT
LUBRICATED BY ANOTHER PARTY.
European REACH Compliance
Timken lubricants, greases and similar products sold in
standalone containers or delivery systems are subject to the
European REACH (Registration, Evaluation, Authorization
and Restriction of CHemicals) directive. For import into the
SHELF LIFE AND STORAGE OF GREASE-LUBRICATED BEARINGS AND COMPONENTS
European Union, Timken can sell and provide only those
lubricants and greases that are registered with ECHA
(European CHemical Agency). For further information, please
contact your Timken engineer.
STORAGE
Timken suggests the following storage guidelines for our
finished products (bearings, components and assemblies,
referred to as “products”):
Unless directed otherwise by Timken, products should be
•
kept in their original packaging until they are ready to be
placed into service.
Do not remove or alter any labels or stencil markings on the
•
packaging.
TIMKEN
Products should be stored in such a way that the packaging
•
is not pierced, crushed or otherwise damaged.
After a product is removed from its packaging, it should be
•
placed into service as soon as possible.
When removing a product that is not individually packaged
•
from a bulk pack container, the container should be
resealed immediately after the product is removed.
Do not use product that has exceeded its shelf life as
•
defined in the Timken shelf life guidelines statement.
The storage area temperature should be maintained
•
between 0º C (32º F) and 40º C (104º F); temperature
fluctuations should be minimized.
The relative humidity should be maintained below 60
•
percent and the surfaces should be dry.
The storage area should be kept free from airborne
•
contaminants such as, but not limited to, dust, dirt, harmful
vapors, etc.
The storage area should be isolated from undue vibration.
•
Extreme conditions of any kind should be avoided.
•
Due to the fact that Timken is not familiar with your particular
storage conditions, we strongly suggest following these
guidelines. However, you may be required by circumstances
or applicable government requirements to adhere to stricter
storage requirements.
Most bearing components typically ship protected with a
corrosion-preventive compound that is not a lubricant. These
components may be used in oil-lubricated applications without
removal of the corrosion-preventive compound. When using
some specialized grease lubrications, we advise you to remove
the corrosion-preventive compound before packing the
bearings components with suitable grease.
We pre-pack most housed unit types in this catalog with
general-purpose grease suitable for their normal applications.
It may be necessary for you to frequently replenish the grease
for optimum performance.
Be careful in selecting lubrication, however, since different
lubricants are often incompatible. You may order housed units
pre-lubricated with a specified lubrication.
When you receive a bearing or housed unit shipment, do not
remove products from their packaging until they are ready for
mounting so they do not become corroded or contaminated.
Store bearings and housed units in an appropriate atmosphere
so they remain protected for the intended period.
TIMKEN ENGINEERING MANUAL
9
TIMKEN
SHELF LIFE AND STORAGE OF GREASE-LUBRICATED BEARINGS AND COMPONENTS
WARNING Failure to observe the following warnings could create a risk of serious injury.
Proper maintenance and handling practices are critical.
Always follow installation instructions and maintain proper lubrication.
Warnings for this product line are in this catalog and posted on
www.timken.com/en-us/products/warnings/Pages/default.aspx.
CAUTION Failure to follow these cautions may result in property damage.
If hammer and bar are used for installation or removal of a part, use a mild steel bar (e.g., 1010 or 1020 grade). Mild steel bars are
Timken products are sold subject to Timken’s terms and conditions of sale, which include its limited warranty and remedy,
European REACH compliance Timken-branded lubricants, greases and similar products sold in stand-alone containers or
delivery systems are subject to the European REACH (Registration, Evaluation, Authorization and Restriction of CHemicals)
directive. For import into the European Union, Timken can sell and provide only those lubricants and greases that are registered
less likely to cause release of high-speed fragments from the hammer, bar or the part being removed.
Do not use damaged housed units. The use of a damaged housed unit can result in equipment damage and/or injury.
NOTE
Components may become damaged and affect the performance and service life of the bearing.
Do not mix components of matched assemblies. Mixing components can reduce the service life of the bearing.
This catalog is provided solely to give you analysis tools and data to assist you in your product selection.
Product performance is affected by many factors beyond the Control of Timken.
Therefore, the suitability and feasibility of all product selection must be validated by you.
which terms may be found at http://www.timken.com/en-us/purchase/Pages/TermsandConditionsofSale.aspx.
Please consult with your Timken engineer for more information and assistance.
Every reasonable effort has been made to ensure the accuracy of the information in this writing,
but no liability is accepted for errors, omissions or for any other reason.
To view the complete engineering catalog, please visit www.timken.com. To order the catalog, please contact your
Timken engineer and request a copy of the Timken Engineering Manual, order number 10424.
with ECHA (European CHemical Agency). For further information, please contact your Timken engineer.
Visit www.timken.com for the most recent version of the Timken
Do not attempt to disassemble unitized bearings.
DISCLAIMER
Updates are made periodically to this catalog.
®
Engineering Manual - Metals Industry Edition.
TIMKEN ENGINEERING MANUAL
10
POPULAR BEARING TYPES IN THE METALS INDUSTRY
POPULAR BEARING TYPES
IN THE METALS INDUSTRY
The following applications are covered in this
section:
Steelmaking.
•
Continuous casting.
•
Rolling mill stands.
•
Radial bearings.
•
Thrust bearings.
•
Auxiliary equipment.
•
TIMKEN ENGINEERING MANUAL
11
POPULAR BEARING TYPES IN THE METALS INDUSTRY
STEELMAKING
STEELMAKING
The main support positions for the ladle furnace present a challenging application for bearings. They experience very high loads
and misalignment at very low speeds. In addition, cyclic and reversing rotation occurs. The Timken solution uses solid or split
high-performance spherical roller bearings mounted in custom-designed housings. The float position housing incorporates cylindrical
roller ladder bearings to accommodate the significant thermal axial growth of the furnace assembly.
SPHERICAL ROLLER BEARINGS
YMB TYPE
Composition: One double inner ring, one
double outer ring, two rows of spherical rollers
with land riding one-piece brass cage.
Application: Basic oxygen furnace (BOF) or
argon oxygen decarburization (AOD) furnace
pivots (trunnions).
Remarks: YMB type is designed for large size
bearings to manage high radial loads when
shaft deflection is important.
Fig. 1. YMB type.
SPLIT TYPE
Composition: One split
double inner ring with
clamp rings, one split
double outer ring, two rows
of spherical rollers with
steel pin-type split cages.
LADDER BEARINGS
CYLINDRICAL ROLLER TYPE
Composition: One top plate, one bottom plate, cylindrical rollers
with spring-centered retainer and one bottom seat.
Application: Linear bearing for float side BOF or AOD furnace
pivot bearing assembly.
Remarks: Used in pairs. Provide ± 65 mm (2.5 in.) axial float.
Fig. 3. Cylindrical roller type.
Fig. 2. Split type.
12
TIMKEN ENGINEERING MANUAL
Application: BOF or AOD
furnace pivots (trunnions).
Remarks: Often used to
replace conventional
spherical roller bearings on
drive-side pivot (trunnion).
POPULAR BEARING TYPES IN THE METALS INDUSTRY
CONTINUOUS CASTING
CONTINUOUS CASTING
The continuous caster presents one of the most challenging environments for bearings. Caster-roll support bearings are subjected to
high loads and low rotational speeds, often at elevated temperatures. Below the bender segments, the Timken ideal solution combines
our high-performance spherical roller bearing for the fixed position and our latest design innovation, the Timken
for the floating position.
®
ADAPT™ bearing,
NEEDLE ROLLER BEARINGS
NA TYPE
Composition: One single inner ring, one
single outer ring, one or two rows of caged
needle rollers.
Application: Bender section support rolls.
Remarks: Low radial cross section with
high radial dynamic and static load rating.
Available with special clearance and higher
stabilizing heat treatment to accommodate
Fig. 4. NA type.
continuous caster operating conditions.
CYLINDRICAL ROLLER BEARINGS
NNCF TYPE
Composition: One double inner ring,
one double outer ring, two rows of
full-complement cylindrical rollers.
SPHERICAL ROLLER BEARINGS
EJ TYPE
Composition: One double inner ring, one double
outer ring and two rows of spherical rollers with
stamped steel cages.
Application: Caster rolls; fixed and float positions.
Remarks: EJ-type spherical roller bearings feature
a hardened stamped steel window-type cage with
face slots for improved lubrication. Designed to
accept misalignment during operation and with
high radial load capacity for maximum reliability.
Fig. 6. EJ type.
ADAPT
Composition: One single cylindrical inner ring,
one single profiled outer ring, full-complement
design with a roller/retainer assembly.
Application: Caster rolls; float position.
™
Application: Continuous caster bender
section support rolls.
Remarks: Available with special clearance
and higher stabilizing heat treatment
to accommodate continuous caster
operating conditions. This type includes
Fig. 5. NNCF type.
direction and permit small axial displacement.
integral flanges on inner and outer rings
and can manage light axial loads in one
Remarks: The ADAPT full-complement roller
bearing is designed specifically for continuous
casters, combining traditional cylindrical and
spherical roller bearing configurations into a new
Fig. 7. ADAPT™.
and high axial displacement capabilities). This bearing also offers
high-static radial load capacity for optional reliability.
design so operators benefit from the key attributes
of both types (simultaneous full misalignment
WARNING
Failure to observe the following warnings could
create a risk of serious injury.
ADAPT™ bearings feature a separable inner ring. Care
must be taken when handling or installing a fully assembled
bearing to prevent the inner ring from accidentally sliding
out of the assembly. When using this bearing to replace a
unitized bearing it is important to check the design of the
installation for positive retention on the shaft.
Proper maintenance and handling practices are critical.
Always follow installation instructions and maintain
proper lubrication.
TIMKEN ENGINEERING MANUAL
13
POPULAR BEARING TYPES IN THE METALS INDUSTRY
ROLLING MILL STANDS
ROLLING MILL STANDS
Rolling mill applications typically encounter very high radial loads and varying degrees of axial load while running at slow to highspeed. To accommodate these operating conditions, roll neck bearings must have enhanced contact surfaces, material strength
properties, and internal geometry and cage characteristics. Available designs include two-, four- or six-row tapered roller bearings,
and multi-row cylindrical bearings.
RADIAL BEARINGS
TAPERED ROLLER BEARINGS
TQOW
Composition: Two double cones
with tapered rollers, one cone
spacer, two single cups, two cup
spacers, one double cup.
Application: Work rolls,
intermediate rolls and backup
rolls. Typically used in mills with
speeds up to 800 m/min. (2600 ft./
Fig. 8. TQOW.
Remarks: The TQOW is a preset four-row assembly with
hardened cone spacers to minimize face wear. The bearing
clearance in the TQOW design can be reset after extended use
by regrinding the spacers.
The bearing is mounted loose on the roll neck and in the chock.
Slots on the cone faces provide lubrication access to cone and
fillet ring faces for reduced wear. Available with spiral bore
groove for additional lubrication access to the roll neck.
min.) when used on backup rolls.
2TDIW
Composition: Two double cones
with tapered rollers, four single
cups, and two or three cup
spacers.
Application: Work rolls,
intermediate rolls and backup
rolls. Typically used in mills with
speeds up to 800 m/min. (2600 ft./
Fig. 9. 2TDIW.
Remarks: The 2TDIW type interchanges with the TQOW type on
external boundary dimensions and achieves the same load rating.
Under combined axial and radial loads, the two central single
cups of the 2TDIW bearing offer better load distribution than the
double cups used in the TQOW type.
min.) when used on backup rolls.
Sealed roll neck
bearing
Composition: Same
construction as the 2TDIW, plus
two main seals, one bore seal,
and O-ring to seal statically in
the chock bore.
Application: Primarily used in
work rolls and intermediate rolls
and some backup rolls.
Fig. 10. Sealed roll neck bearing.
Remarks: The sealed roll neck
bearing is supplied as a unitized, preset assembly with or
without grease.
TQITS
Composition: One double
cone and two single cones all
with matched tapered bores,
four single cups, three cup
spacers.
Application: Backup rolls,
typically used in high-speed
mills where strip speeds
exceed 800 m/min. (2600 ft./
min.).
Fig. 11. TQITS.
Remarks: The TQITS type
mounts tight using a 1:12 taper on the roll neck and the bearing
bore for accurate control of the interference fit. Typically used
on high-speed mills to minimize neck wear.
14
TIMKEN ENGINEERING MANUAL
POPULAR BEARING TYPES IN THE METALS INDUSTRY
ROLLING MILL STANDS
CYLINDRICAL ROLLER BEARINGS
Fig. 12. TQOWE.
Fig. 13. TQITSE.
TQOWE and TQITSE
Composition: Same
construction as the TQOW
and TQITS respectively
with cone extension on
one or both sides of the
bearing.
Application: Work rolls,
intermediate rolls and
backup rolls.
Remarks: The TQOWE
and TQITSE versions
include cone extensions
to accommodate chock
seals. This bearing design
allows an optimal chock
seal running surface.
The seal integration
permits the bearing to be
positioned closer to the
roll face, which improves
the neck stiffness.
RX
Composition: Tw o
cylindrical inner rings,
two flanged outer rings
and separated rib rings
for roller spacing.
Typically includes a pintype cage(s).
Application: Backup roll
Fig. 14. RX.
Remarks: The bearing is mounted tight on the roll neck and loose
in the chock when used on backup rolls. Generally provided with
semi-finished (CF) inner ring races to be finished ground by the
customer once mounted on the roll neck. Separated rib rings
allow for complete disassembly for inspection. The RX style
is usually preferred in bearings above 400 mm (15.75 in.) bore.
Long product mill applications are generally supplied as preset
assembly and mounted tight on the roll neck.
radial position for flat
product mills. Roll neck for
long product mills.
RY and RYL
Composition: Typically one
single-piece inner ring, two
outer rings with triple flanges
(solid ribs). Fully machined
brass (RY) or steel (RYL) cages.
Application: Roll neck for long
product mills.
Remarks: The most recent RYL
design is specifically designed
Fig. 15. RY and RYL.
features a machined-steel cage and enhanced design features
to maximize bearing life and optimize bearing handling. For
specific applications, four-row cylindrical roller bearings also
can be supplied with spiral grooves on inner ring bore, extended
inner rings or tapered bore.
for long-product mills and
TIMKEN ENGINEERING MANUAL
15
POPULAR BEARING TYPES IN THE METALS INDUSTRY
ROLLING MILL STANDS
THRUST BEARINGS
Applications mounted with cylindrical roller bearings, oil-film bearings or systems with axial shift or roll crossing, generally need an
additional thrust bearing.
TAPERED ROLLER THRUST BEARINGS
Fig. 16. TDIK.
Fig. 17. TDIK with
spring system.
TDIK
Composition: One double cone with tapered
rollers, two single cups, spacer or spacerless.
Application: Backup and work roll thrust
positions for flat product mills.
Remarks: These bearings come designed
with steep angles to accommodate thrust
in both directions. Cups and cones are
mounted with a loose fit. The cone is keyed
onto the shaft to prevent cone rotation and
bore fretting.
TDIK with spring system
Timken developed a version with
a spring system in the cups without a spacer
to ensure that the unloaded cup always
remains seated and to help prevent any
roller skewing.
Application: Work rolls, intermediate rolls
with axial shift, and backup roll equipped
with cylindrical roller bearing.
TDIK sealed with spring system
Timken developed the sealed version of the
TDIK with a spring system.
TTDWK and TTDFLK
Composition: One double central ring with tapered rollers, two
outer rings.
Application: Heavy-duty flat product mills with axial shift and
long product mills.
Remarks: Double-acting thrust bearings come available in two
versions with tapered central ring or flat central ring. Mounted
loose on the neck and in the housing.
Fig. 19. TTDWK. Fig. 20. TTDFLK.
The tapered central ring version enables a smaller overall width
of the bearing. These TTDFLK assemblies can be provided with
or without an outer spacer. However, we generally prefer to use
the design without outer spacers and include a spring mounting in
the chock shoulders to ensure that the rollers of both rows remain
properly seated (see configuration on page 55).
Application: Work rolls, intermediate rolls
with axial shift, and backup roll equipped
with cylindrical roller bearing.
Fig. 18. TDIK with sealed spring system.
16
TIMKEN ENGINEERING MANUAL
POPULAR BEARING TYPES IN THE METALS INDUSTRY
ROLLING MILL STANDS
SPHERICAL ROLLER THRUST BEARING
TTHD
Composition: Two tapered thrust rings, cage or cageless.
Application: Thrust positions for piercing mills, sendzimir mills
and auxiliary equipment.
Remarks: This design offers up to 40 percent more capacity
than cylindrical and spherical bearings with the same envelope
dimensions. Used only when axial loads are unidirectional. Medium
speed capability when provided with a cage. A cageless design is
available for high loads and low speeds.
Fig. 21. TTHD.
TTHDFLSX and TTHDFLSV
Composition: Identical to the TTHD construction with a top ring
generally made with convex outer face (TTHDFLSX). A concave
(TTHDFLSV) top ring also can be supplied if needed.
Application: Screwdown thrust bearing.
Remarks: Full-complement design for maximum capacity. Lifting
holes exist in each ring for handling purposes.
Both designs are also available with a tapered bottom race design
(TTHDSX and TTHDSV).
TSR
Composition: One single inner ring with spherical
rollers with cage retainer and one single outer ring.
Application: Thrust position for gearboxes and
auxiliary equipment.
Remarks: Type TSR spherical roller thrust bearings
maintain a high-thrust capacity and accommodate
misalignment.
Fig. 24. TSR.
2TSR assembly
Composition: Two single
inner rings with spherical
rollers and cage retainer
installed in a sleeve and
two single outer rings, all
mounted in a carrier.
Application: Thrust
position for gearboxes
and auxiliary equipment.
Fig. 22. TTHDFLSX.
Fig. 23. TTHDFLSV.
Remarks: To maintain
loading in the row
unloaded by the axial
Fig. 25. TSR assembly.
TIMKEN ENGINEERING MANUAL
load, the whole assembly
is preloaded using springs
mounted in the carrier.
17
POPULAR BEARING TYPES IN THE METALS INDUSTRY
AUXILIARY EQUIPMENT
AUXILIARY EQUIPMENT
Timken offers a wide range of bearings for auxiliary equipment applications such as gear drives, table rolls, coilers, end coilers,
levelers, pinion stands, handling equipment and more.
TAPERED ROLLER BEARINGS
Fig. 26. TS.
TS
Composition: One single cone with tapered
roller and one single cup.
Application: Saws, guiding rolls, scrap choppers
and small drives.
Remarks: The TS is the most common tapered
roller bearing that allows the designer a
large choice of mountings. TS bearings
always are fitted in pairs, whether mounted
directly like a TDI or indirectly like a TDO.
TDI AND TDIT
Composition: One double cone, two
single cups, spacer or spacerless.
TDI version with straight
bore (illustrated).
TDIT version with a tapered bore.
TDO
Composition: Two single cones,
one double cup and one cone
spacer.
Application: Mill drives, pinion
stands, coilers, uncoilers, side
trimers and scrap choppers.
Remarks: The TDO is a preset
assembly and works at fixed and
floating positions on rotary shaft
applications. Holes and circular
grooves are normally provided
Fig. 28. TDO.
purposes, one counterbored hole is usually included. This permits
the provision of a locking pin to keep the loose-mounted cup from
rotating at the floating position. This is then referred to as a CD cup.
on the double cup for lubrication
TNA AND TNAT
Composition: Similar to the TDO
version. Cone small faces are
extended to abut and eliminate the
need for a spacer.
TNA version with straight
bore (illustrated).
Application: Edgers, bar mills and rod
mills. We suggest the tight-fitted TDIT
assembly when mill speeds exceed 600
Fig. 27. TDI and TDIT.
Remarks: TDI/TDIT bearings can be delivered as a preset
assembly. The cups and cones are normally mounted loose on
the top version. The bearing works at fixed positions on rotating
shaft applications. For a rotating housing application, it can float
on the stationary shaft.
18
TIMKEN ENGINEERING MANUAL
m/min. (2000 ft./min.).
TNAT version with tapered
cone bores.
Application: Mill drives, pinion
Fig. 29. TNA and TNAT.
Remarks: Preset assembly. These bearings provide a solution
for many fixed or floating bearing applications where simplicity
of assembly is required.
stands, coilers and uncoilers.
POPULAR BEARING TYPES IN THE METALS INDUSTRY
AUXILIARY EQUIPMENT
SPHERICAL ROLLER BEARINGS
TNASWH
Composition: Same as the TNA
bearing with one heavy section
double cup and two closures.
Application: Levelers, chock wheels,
conveyor car wheels, various railcars
and crane sheaves.
Remarks: Preset assembly with
profile cup. Cones mounted loose on
the stationary shaft. Assembly also
could function as a wheel.
Fig. 30. TNASWH.
WARNING
Failure to observe the following warnings could
create a risk of death or serious injury.
EM TYPE
Composition: One double inner ring, one double
outer ring, two rows of spherical rollers with
roller-riding brass cage(s).
Application: Mill drives, pinion stands, coilers
and uncoilers.
Remarks: EM-type bearings manage high
radial loads when shaft deflection is important.
Fig. 31. EM type.
EJ TYPE
Composition: One double inner ring, one
double outer ring and two rows of spherical
rollers with stamped-steel cages.
Never spin a bearing with compressed air.
The components may be forcefully expelled.
Application: Gear drives, table rolls and
auxiliary equipment.
Remarks: EJ-type spherical roller bearings
feature a hardened stamped steel windowtype cage with face slots for improved
lubrication flow. It offers high load ratings for
longer life.
Fig. 32. EJ type.
TIMKEN ENGINEERING MANUAL
19
POPULAR BEARING TYPES IN THE METALS INDUSTRY
AUXILIARY EQUIPMENT
CYLINDRICAL ROLLER BEARINGS
ONE-ROW EMA TYPE
Composition: One single inner ring, one
single outer ring, one row of cylindrical
rollers with a one piece, land-riding
window-type brass cage.
Application: Gear drives, electric motors.
Remarks: Available in multiple configurations:
NU, N, NJ, NF and more.
Fig. 33. One-row
EMA type.
TWO-ROW CYLINDRICAL
ROLLER BEARINGS
Composition: One single inner ring,
one single outer ring, two rows of
cylindrical rollers with a one piece,
land-riding, finger-type brass cage.
Application: Gear drives, crop shear.
Remarks: Standard cage design
includes a drilled pocket, finger-style
brass retainer.
BALL BEARINGS
DEEP-GROOVE RADIAL
BALL BEARING
Composition: Inner and outer ring with a cage
containing a complement of balls.
Application: Gear drives, electric motors, fly
wheels and auxiliary equipment.
Remarks: The standard deep-groove
construction handles radial and light axial
loads for moderate- to high-speed applications.
Available in multiple configurations.
Fig. 35. Deepgroove radial ball
bearing.
ANGULAR-CONTACT
BALL BEARING
Composition: Inner and outer ring with a cage
containing a complement of balls.
Application: Work roll thrust position for long
product mill. Auxiliary equipment.
Remarks: Designed for combination radial and
axial loading. Single-row bearings have thrust
capacity in one direction. Typically used in pairs
to accommodate thrust in both directions.
Fig. 34. Two-row
cylindrical roller bearings.
20
TIMKEN ENGINEERING MANUAL
Fig. 36. Angularcontact ball bearing.
APPLICATION CONSIDERATIONS AND BEARING SELECTION
APPLICATION
CONSIDERATIONS
AND BEARING SELECTION
The following processes are covered in this
section:
Steelmaking.
•
Continuous casting.
•
Rolling mill.
•
Flat product rolling.
•
Long product rolling.
•
Bearing solutions: radial positions.
•
Work and intermediate rolls: flat product mills.
•
Work rolls: long product mills.
•
Backup rolls.
•
Bearing solutions: axial positions.
•
Auxiliary equipment.
•
Main mill drive and pinion stand gearboxes.
•
Pay-off and rewind reels.
•
Shears and shear drives.
•
Table rolls.
•
TIMKEN ENGINEERING MANUAL
21
APPLICATION CONSIDERATIONS AND BEARING SELECTION
STEELMAKING
The basic processes for the production of semi-finished and
finished products includes the following stages: mining the ore,
smelting, alloying, casting, rolling and finishing. Depending on the
metal type and production method, the processes used during
the smelting stage, where the metal is extracted from the ore,
can vary dramatically. After the smelting stage, the processes
for metals production have much more in common.
This section outlines the critical bearing applications used in the
metals production process after the smelting stage. Specifically,
it covers applications in basic oxygen furnaces (BOF) and
continuous casters used in steel production, as well as hot-rolling
and cold-rolling mills that can be used in the production of flat
and long metal products.
STEELMAKING
THE BASIC OXYGEN FURNACE
In the BOF (fig. 37) and the mechanically similar bottom-blown
oxygen process (BBOP) and argon-oxygen decarburization (AOD)
furnace, steel is melted for final alloy adjustment and purification.
The three furnaces are all types of converters. Each type has its
own configuration but they all are generally comprised of the
following equipment:
Furnace vessel. The furnace vessel usually resembles a
•
barrel-shape with a dished bottom and a conical top. The
inside includes a refractory material lining and a retractable
hood that closes off the top of the conical section.
Trunnion ring. A trunnion ring wraps around and supports
•
the vessel. The trunnion ring allows the vessel to tip
back and forth, pivoting on two stub shafts about 180
degrees apart.
Main support bearing and
housing assemblies
Drive assembly
Fig. 37. Basic oxygen furnace.
22
TIMKEN ENGINEERING MANUAL
Furnace vessel
Trunnion ring
APPLICATION CONSIDERATIONS AND BEARING SELECTION
Top ring
Taphole
Trunnion ring
Slag shield
Nose (lip)
STEELMAKING
Main support bearings and housing assemblies. These
•
bearings come mounted to the stub shafts on the trunnion
ring and support the entire weight of the loaded furnace
and its drive.
Drive assembly. The drive assembly rotates the vessel
•
forward and backward from the vertical position through
approximately 135 degrees in each direction. In modern
vessels, a trunnion stub shaft supports the drive and a
torque arm anchors it to the foundations.
ring
Top cone
Float
bearing
Fixed bearing (drive side)
Support brackets
Torispherical bottom section
Fig. 38. Bearing support on basic oxygen furnace.
Barrel section
Support pier
Safety
lining
Working
lining
The second key bearing locations exist within the drive for the
BOF rotation. The drive is generally comprised of several smaller
enclosed gear reducers and motors mounted to a common
gear case that also enclose the bull gear. Each of the smaller
drive units has its own pinion that meshes with the bull gear.
Bearing selection for this application follows traditional power
transmission guidelines.
MAIN SUPPORT POSITIONS
The preferred bearing type for main support trunnion positions is
the spherical roller bearing due to its high-radial capacity, ability
to function as a fixed position bearing and high-misalignment
capability. Bearing selection is based primarily on static load
capacity because of the slow rotational speed. The target static
capacity-to-load ratio is 3:1 or greater. Typical sizes fall in the
range of 600 mm (23.62 in.) bore to 900 mm (35.43 in.) bore but go
as high as 1250 mm (49.21 in.).
We also must consider when establishing the bearing
requirements unique application conditions. These conditions
may include:
Structural deflections that may exceed ±1.5 degrees.
•
Very high loads at very low speeds and elevated
•
temperatures. This is particularly important in relation to
lubrication.
Oscillating motion through a maximum of 270 degrees of
•
rotation.
Significant axial growth of the trunnion ring due to
•
temperature changes over a large bearing spread up to
12 m (40 ft.).
There are two key positions for roller bearings in BOF applications.
The first and most challenging include the two main support
positions for the vessel and its trunnion ring (fig. 38). The second
lies within the drive.
The main support position bearings allow the vessel to tip forward
for raw material loading and for pouring out the refined steel.
The vessel tips backwards after the refined steel is poured off
(teemed) for slag removal. The melting completes with the vessel
in the vertical position. The combined weight of the vessel,
trunnion ring and the melt max exceed 1000 metric tons. In modern
designs, where the drive mounts directly to the trunnion support
shaft rather than to the foundation, the loads can approach 1500
metric tons.
Significant vibration from the agitation of the steel during
•
melting and from blowing oxygen through the liquid steel.
Vibration is particularly extreme in AOD furnaces.
Highly contaminated operating environments and the
•
resulting demanding sealing requirements.
Practical accessibility for inspection and future bearing
•
replacement.
For these applications and operating conditions, Timken suggests
using a complete bearing and housing system that is tailored
to the specific installation. This system generally includes two
housed assemblies – one for the float position and one for the
fixed position.
TIMKEN ENGINEERING MANUAL
23
APPLICATION CONSIDERATIONS AND BEARING SELECTION
Ladder Bearing Arrangement
STEELMAKING
BOF trunnion float position
The float position assembly (fig. 39) generally mounts on the
non-driven side of the vessel and must accommodate several
centimeters (inches) of axial movement. The typical bearing
solution mounts the support bearing in a cartridge supported
on a pair of inclined linear bearings, often referred to as ladder
bearings (fig. 40).
The ladder bearings typically offer a float capability of ± 60 to
100 mm (2.5 to 4.0 in.) from its centered position. The static load
capacity of each ladder bearing approximately equals that of the
main support bearing.
FLOAT SIDE OF BOF HOUSING ASSEMBLY:
Full ring to contain radial bearing.
This design does not require the float bearing to move axially in
its housing. This eliminates the risk of galling and wear that can
occur on the bore or outer diameter surfaces when high radial
load forces the bearing to move. Ladder bearings are inclined
towards each other in a shallow V configuration to stabilize and
locate the cartridge in a crosswise direction.
The main support bearing generally has a loose fit on the trunnion
shaft and in the cartridge to facilitate installation and removal. The
floating cartridge assembly and ladder bearings mount in a fully
enclosed steel housing that also includes the main seals.
Bearing cartridge floats on ladder bearing to
accommodate thermal expansion.
Complete assembly installed as a unit;
all bearing areas completely sealed.
Fig. 39. Float side of BOF housing assembly.
Plain seatSpherical seat
Fig. 40. Ladder bearing arrangement.
24
TIMKEN ENGINEERING MANUAL
APPLICATION CONSIDERATIONS AND BEARING SELECTION
Bearing with tapered bore and adapter sleeve.
STEELMAKING
BOF trunnion fixed position assembly
The fixed position assembly is simpler and smaller because it
does not require the floating internal cartridge or ladder bearings.
The fixed position is usually on the drive side of the furnace. One
important design feature of the fixed position assembly involves
the ability to replace the original standard bearing (fig. 41) with
a split version (fig. 42). This proves necessary because the
replacement of a standard bearing would require the removal
of the complete drive assembly. This is a difficult and very timeconsuming task.
FIXED SIDE OF BOF HOUSING ASSEMBLY:
Initial mounting of standard bearing is done in one of two ways.
Either mount a straight bore bearing directly to the shaft using a
tight fit; or mount a tapered bore bearing using a tapered adapter.
The use of the adapter allows final control of the bearing
position on the shaft and some adjustment of the bearing
internal clearance. The adapter also facilitates bearing removal
through the use of hydraulic pressure that frees the bearing from
the adapter.
Fig. 41. Standard bearing.
Fig. 42. Split bearing.
Bearing with tapered bore and adapter sleeve.
TIMKEN ENGINEERING MANUAL
25
APPLICATION CONSIDERATIONS AND BEARING SELECTION
STEELMAKING
The use of a split replacement bearing facilitates removal of the
standard bearing. First remove the housing cap, slightly raise the
trunnion shaft, then remove the standard bearing by cutting or
fracturing it into halves. If a tapered adapter was used, remove
it in the same manner. An axial slot in the adapter-bore facilitates
burn off without trunnion shaft damage. The new split bearing
builds up around the shaft before lowering back down into
the housing.
The tight-fitted adapter helps reduce the risk of impact damage
to the bearing components due to potentially violent vibration of
the vessel during operation.
Spherical roller bearings used in BOF housings have a standard
misalignment capability of 1.5 degrees. When higher misalignment
is required, the bearing may be supplied with a wide outer ring
that increases the misalignment capability to 3 degrees. Timken
identifies bearings with this feature using W57 in the part number.
Timken usually supplies assemblies with sleeves located on the
trunnion shaft on both sides of the bearing. The backing sleeves
facilitate axial clamping of the complete assembly onto the shaft
and function as seal riding surfaces. When installing a split
bearing, replace these sleeves with narrower versions to make
room for the wider inner ring.
Because BOF bearing assemblies must function in the dustcontaminated and often hot environment of a steel mill, effective
sealing is critical. Bearings subjected to contamination by
abrasive converter dust may suffer premature wear. To help
prevent this, robust sealing accommodates the displacement
of the shaft that results from trunnion ring thermal growth
and deflection.
Additional considerations for trunnion
bearing selection
Furnaces must tolerate the significant and sometimes violent
vibration that occurs during furnace charging, melting and
purification. Consider these factors during the design and
selection of bearings and housings. For optimal bearing
performance, we prefer light-to-tight bearing fits on the shaft
and in the housing. However, it also is important to consider the
ease of installation and removal.
Minimized bearing radial clearance limits risks of fretting
corrosion (false brinelling) of the rollers and raceways. Minimizing
operating clearances and applying light-to-tight fits also improves
the seating of the bearing’s inner and outer rings and maximizes
the load zone within the bearing. These bearings are traditionally
through-hardened but Timken also offers the bearings with casecarburized components for applications where shock loading is
a particular concern.
In this application, the lubricant primarily functions to help prevent
corrosion and to help keep contaminants out. To achieve this,
we suggest 100 percent grease fill of the bearing and housing
cavity. These furnaces use an extremely slow rotational speed.
Rollers and raceways cannot generate a normal lubricant film.
A heavy consistency, extreme-pressure (EP) grease with a very
high base-oil viscosity can improve lubrication conditions. We
suggest synthetic base oil, lithium complex types.
Timken also manufactures split and special bearing designs and
can review your specific application needs. For more details,
contact your Timken engineer.
26
TIMKEN ENGINEERING MANUAL
APPLICATION CONSIDERATIONS AND BEARING SELECTION
CONTINUOUS CASTING
The continuous caster for producing steel slabs (fig. 43), blooms
and billets represents the most significant development in steel
production since the Bessemer converter. Compared to the
traditional, individually poured cast ingot route, the continuous
caster offers significant improvements in yield, consistency
and energy efficiency as well as reduced emissions and
waste products. In addition, the ability to cast thinner slabs
(alloy dependent) may significantly reduce the subsequent hot
rolling requirements.
Generally, the conventional slab caster produces slabs between
180 mm (7 in.) and 300 mm (12 in.) thick at speeds of 0.8 to
2.0 m/min. (2.6 to 6.5 ft./min.). The medium slab caster produces
slabs between 100 mm and 180 mm (4 and 7 in.) thick at speeds of
1.0 to 3.0 m/min. (3.3 to 10 ft./min.). The thin slab caster produces
slabs less than 100 mm thick at speeds of 3.0 up to 6.0 m/min. (10
to 20 ft./min.).
CONTINUOUS CASTING
Fig. 43. Typical continuous slab caster layout.
TIMKEN ENGINEERING MANUAL
27
APPLICATION CONSIDERATIONS AND BEARING SELECTION
CONTINUOUS CASTING
CASTER DESIGN
Fig. 44 shows the main components of the continuous caster. Nearly all installations possess this overall configuration, although minor
variations will exist depending on the original equipment manufacture's technology, steel grade being cast, and end-user preferences.
The following description refers to slab casting but bloom and billet casters can receive similar considerations.
Foot rolls
Bender section
Fig. 44. Continuous slab caster schematic.
Horizontal withdrawing section
SEQUENCE OF OPERATIONS
First, molten steel transfers from the steelmaking furnace to the
casting platform in a ladle.
Then the ladle pours the molten steel into the tundish through
a shroud.
Another shroud takes the molten steel into the water-cooled mold.
The mold lining, typically comprised of a copper alloy, oscillates
to minimize the chance of the steel sticking to the mold. The steel
solidifies at the surface to form its shape (slab, billet or bloom)
before it emerges from the mold, attached to the dummy bar. The
dummy bar detaches at the exit end of the caster.
Once the slab leaves the mold, it proceeds through the top
zone (foot rolls) via the bender to the curved (bow) section
through a straightener section and finally to the horizontal
withdrawal section.
A straight-mold equipped caster includes a bender section that
forms the slab to match the curvature of the bow section. Casters
with a curved mold do not require the bender.
Bow section
Straightener section
Below the mold, caster sections break down into eight to 12
discrete segments, each with five to seven roll pairs with one roll
of each pair above and one below the slab. One of the roll pairs
is a driven pair that controls the speed of the slab. The other,
idler rolls, support the slab and maintain its thickness and shape.
Many casters will make a small reduction in the slab thickness as
it descends through the bow section. This is referred to as soft
core reduction and is done for metallurgical reasons rather than
for slab thickness control.
The top and bottom rolls are mounted on two separate frames and
adjustment is provided to allow setting the position of the top rolls
relative to the bottom rolls. Each of the individual roll segments
can be removed from the caster as a complete assembly.
External, high-volume water sprays cool the slab. The
support rolls also are water cooled via rotary couplings and
internal passages. Cooling the rolls and bearing housings
controls component temperature and the integrity of their
mechanical properties.
After the slab exits the straightener segment(s) it passes through
the horizontal withdrawal segments and is cut to length with a
traversing gas torch. Finally, the slab is brought to a cooling yard
where it is marked before being transferred to the hot rolling mill.
28
TIMKEN ENGINEERING MANUAL
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