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Basics of Rolling Mill Guide Design

ByMorgan Construction Company- A Siemens CompanyWorcester, MA 01605 USA

Page 2 20-Mar-09 MT LR ServicesStrictly Confidential

R. Stanard GuideDesignBasics.ppt

Contents

IntroductionLong rolling mill guide design parametersRestbars and other ancillariesOptical alignment equipmentRod finishing mill guides



SVAI Long Rolling (LR) Services:Spares, Guides, Upgrades & Services

Global Organization:Morgan WorcesterSiemens VAI Italy (Pomini)Morgan IndiaMorgan ShanghaiSiemens VAI UK (Ashlow – Morgan Europe)Siemens VAI Brazil (Morgan do Brazil)

and the other Siemens VAI Service locations throughout the world

With this expanded network we can be even closer to customers tosupport all activities and requirements



SVAI Long Rolling Services

Mission:Maximize Mill Utilization

UPGRADES

RECONDITIONING

SPARES

AUDITS

MAINTENANCE

GUIDESSERVICES

TRAINING

REBUILDS

A growing global organization focused on the needs of all rolling mills

GUIDES



Guide Equipment

It all started in 1879 with the first of many patents from Company founder Charles Hill Morgan

Together with Siemens VAI guides (Ashlow) we offer the most expansive guiding solutions of any guide supplier in the industry



Siemens VAI guides

Main benefits:

Highest competitiveness

Quick and simple adjustment

Minimum maintenance requirements

Long operational service life



Siemens VAI guides

Our vast guide portfolio covers the following applications and more....

Applications: including but not limited to rounds, rebars, flats, squares, hexagons and angles

Also providing:Restbars

Interstand loopers and guiding

Air/oil lubrication systems

Optical setting equipment

Water cooling headers

High-speed flaw detector guides

Leading technology in multi-slit rolling with over 40 references worldwide



Guide Design and Rolling

The Basics of Guide Design AgendaBasic Rolling Requirements

It all starts in the Roll ShopBasics of Guide Design

Equipment design and operating parametersGeneral Guide Topics

Types of guides, considerations etc.



Basic Rolling Requirements

Conventional Rolling StandsMill Roll Groove Pass Alignment

A program for mill roll pass groove preparation and roll tracking is requiredTogether is standard practices the rolls and stands are consistently prepared for the rolling millThe productivity of the rolling mill is directly related to the roll shop




Conventional Rolling StandsRestbar and Saddle Alignment

The restbar elevation and position must be properly set and maintainedPremature guide failures and increased wear can be a result of poor restbar design or conditionPoor positioning results in hooked front ends, cobbles, and guide failures




Restbar and Saddle AlignmentMechanical tools for checking alignment



General Guide Topics

Restbars and Guide MountingsRestbar designs must be durable and provide years of accurate location of guidesMounting and clamping surfaces must be maintainedAdjusting restbars must be rebuilt and maintained for correct operationSecondary adapter plates and fine pass adjustment bases can be used for smaller guides or guides requiring more location accuracy



Restbars & Guide Mounting Equipment

Traversing and fixed restbarsGuide mounting adapter platesFine-pass adjusting bases




Conventional Rolling StandsStand alignment to interconnecting equipment

Proper alignment through all areas of the mill must be maintainedPremature guide failures and increased wear can be a result of poor alignmentForcing equipment out of position is not sound rolling practice




Conventional Rolling StandsRoll Groove Cooling

Pass design, guide design, and cooling header design all must beconsidered together for proper roll coolingAdvances in materials and methods for mill roll manufacture demand increased awareness and optimization of roll cooling designsProper roll cooling reduces pass wear, increases product quality and mill utilization and decreases operating costs

Typical Static Delivery Guide With-HeaderTwist Delivery Guide With-Header




Conventional Rolling StandsRoller guide cooling and lubrication

Review of the piping and systems for applying the roller cooling and bearing lubrication is required before and during the guide service time in the millFailure to monitor the roller cooling and bearing lubrication directly causes roller and bearing failures and cobbles




Cantilevered Rolling StandsMill roll groove alignment

Mill roll grooves must be properly cut and inspectedMounting sleeves and tooling must be inspected and proper procedures followedSome variables can be reduced with adjustments to the guiding equipment




Cantilevered Rolling StandsRoll housing preparation and condition

A schedule for maintenance must be createdInspection and proper procedures must be followed to maximize the equipment lifeDamaged or worn housings can result in increased guide delays and operating costs




Cantilevered Rolling StandsBracket and saddle alignment

Mounting brackets rigidly align and hold the guides to the roll housingThe mounting surfaces and clamping equipment must be free of damage and scaleA schedule for maintenance must be created and spare parts available




Cantilevered Rolling StandsRoll cooling and pass life

The design requirements for roll cooling increases with mill roll hardness and rolling speedRoll cooling headers need to be inspected regularly at mill roll and guide changes Worn, damaged, or poorly designed headers directly affect pass life and product quality




Cantilevered Rolling StandsFlutter and the finishing mill

A great deal of testing of the effects of the flutter related to feed area, steel grade, and temperatures has allowed Morgan to make advances in roll pass design to reduce some of the flutter and produce the highest quality finished product tolerances at the world’s fastest finishing speedsPlease contact Morgan Rolling Services for assistance in this area



Basics of Guide Design

Design input requirements for guides (required for all mill locations and installations)

Mill roll maximum and minimum diameterMounting restbar dovetail dimensions and locations from the center of the mill standThe distance from the stand centerline to the interconnecting equipmentThe distance between the rolling standsThe location and design of the mill roll cooling headersThe pass groove details of the incoming feed sectionThe pass groove details of the outgoing rolled section




Design input requirements for guides (cont’d)The mill roll partings for each pass groove and section rolledThe key tolerance and size if the restbar has a key and keyway designThe inside dimension of the stand housing windowThe distribution of passes along the mill roll barrelThe dimension from the end of the roll barrel to the mill roll chocksThe dimension of the strand centers (for multi-strand mills only)




Design input requirements for guides (cont’d)

Additional requirements for cantilevered stands only

The dimension of the roll housing to the centerline of strandThe location of the pinion bore to the guide mounting location and the dimension of the eccentric throw The design of the seal plateThe dimensions for the mounting holes and keyways for guide mounting brackets




Design input requirements for guides (cont’d)The main point is that ALL input requirements must be considered when designing and installing guides to get the optimum performance and reliability




What guides should be supplied?Once all the parameters are gathered a final decision is required to determine what type of guide is requiredA review of the progression of passes is required to understand the guiding requirements and options




Stable pass progressionsStable progressions typically do not require secondary support from direct contact guidingSome examples of stable progressions…




Stable pass progression examples…




A few Un-stable pass progression examples…




Review of pass progressions leads to the final decision of the type of guide to be used for the specific application

There are many reasons to choose a guide design but all factors and requirements must be reviewed for the correct choice for each rolling location

A simple but critical type of guide in the mill is the static receiving guides that deal with a wide variety of stable pass progressions




Static Receiving Guides

Illustration for receiving guide discussion




Static Receiving GuidesThe guide bore must be less than the full width on face of that stands work roll passThe guide bore is typically 85-90% of said pass width of faceThe length of the rifling is typically 2-3 times the guide bore for stabilityWorn static receiving guides lead to delivery guide cobbles and twist guide failures from hooked and knuckled head ends




Static Delivery GuidesThe main function of delivery guides is to ensure the smooth passage of the bar from the rolling stand to the next piece of mill equipmentThere are two basic guide types: stripper and catcher

Stripper guides are used to minimize hooksCatcher guides are used to reduce change time

The chance of cobbles must be considered with the guide and mounting bracket design to protect the rolling mill stand




Static Delivery GuidesIllustration for delivery guide discussion




Roller Entry Guide DesignsTwo basic guide design types, leaf and block

Both types have design points that must be reviewed for each application and operator preference

Two and four roller guides have specific application points and must be reviewed for each application and operator preference

The back rollers of the 4 roller guide are set slightly larger than the front rollers to promote a rollerized funnel effect




Roller Entry GuidesThe main function of the roller entry guide is to prevent the rolled section from rotating in the work roll pass grooveExiting product tolerance is a direct result of durability and accuracy of the guide setting and guide roller and static insertdesignThe static entry insert must minimize the impact on the guide roller and bearings but must not rub on the bar through the length of the billetThe guide roller design must be carefully reviewed to maximize roller and bearing life and product quality




Roller Entry Guide Roller DesignProfile and V-grooves are the two main typesFor hard-metal mill rolls the profile rollers are preferred and outperform V-groove rollersBoth roller types need to be designed to utilize the full operating range of the roller entry guide assembly to provide the maximum payback for the rollers




Roller Entry Guide Roller DesignComparison of V-groove versus profile rollers

V-groove rollers typically contact at around 65% of W.O.F.Profile rollers should have minimum contact of 75%




Roller Entry GuidesRoller design

W.O.F. ContactAssembly capacityInsert clearanceRoller parameters




Roller Entry GuidesInsert design with twisting entering section into guide




Roller Entry Guides (cont’d)The insert clearances are 15-30% larger than the guided section based on location and speed of the guided sectionThe guide roller needs to support at least 75% of the oval pass width and can approach 100% for the smallest leader ovals for high-speed wire rodsBearing lubrication and guide roller cooling are key to guide life




Roller Entry Guide NosepieceThe nosepiece is used to fill the space from the guide roller to the mill roll biteWith correct settings and alignment the nosepiece should never be in contact with the rolled sectionThe nosepiece width is typically equal, or nearly equal, to the dimension of the height of the preceding roller entry guide static inserts




Other Roller Entry GuidesThe open top 4 roller guide with symmetrically adjusting base provides the flexibility to guide the process passes for flats, channels and angles with only adjustments for width and centering spacer shapeA top adjusting three roller guide is often used for angle and channel passes but the guide is limited to longer distances fromthe roll bite

The main requirement for this guide are for the production of sharp apex angle sections




Roller Twist Delivery Guide DesignsFour basic guide design types: link, top adjust, outboard, and cassette.Link-style provides design and rolling flexibilityTop adjust provides ease of maintenance but limited flexibilityOutboard provides ease of maintenance and rolling flexibility but is limited in installation optionsCassette design offers strength but increased maintenance and limited installation optionsAll types have design points that must be reviewed for each application and operator preference




Roller Twist Delivery GuidesThe main function of the roller twist delivery guide is to apply a force to rotate the rolled bar to the required rotational position for the next rolling standThe delivery guide insert bore must have clearance for the horizontal and twisted section to ensure no rubbing occursThe guide roller shape must consider the guide operating capacity, maximum roller diameter, and point of contact for the application of the twisting forceBearing lubrication and guide roller cooling are key to guide life




Roller Twist Delivery GuidesCalculation of twist at the RE guide rollers

X = Distance from stand to standZ = Distance back from stand to RE guide rollersY = Distance from stand to Twist guide rollersT = The required twist angle

(see page 33 in guide design document for illustration)

X – Z = 90o

Y TSolve the ratio for ‘T’ where ‘T’ is

the twist angle in degrees




Roller Twist Delivery GuidesLayout of guide rollers

Show rolled section at calculated twist angle TRotate rollers to near maximum guide twistConstruct tangent on rolled section at 75% W.O.F.Construct gauge diameter between two guide rollers




Roller Twist Delivery GuidesDelivery inserts

Basic design is the same for a delivery guide, either stripper or catcher typeThe insert must consider the back-twist of the rolled section




Guide Roller Bearing DesignThe proper tools must be used to install any bearings with imparting damage before the bearing is even usedTapered roller bearings for slower speeds and higher loadDeep groove ball bearings for higher speeds and longer bearing lifeBall bearing spacers must be undamaged to prevent bearing preload when installed




Optical Alignment of Guides and MountingsBench Optics for use in the roll shopPortable Optics for use in aligning restbars and guide mounting bracketsSystem allows for guide life and product tolerances not achievable with mechanical guide setting techniques



Universal bench optics to setup a large range of roller guides in the roll shop

Bench Optics Alignment Equipment



Provides consistent setting of guides in the roll shop by all operatorsNo variability from operator feel and guesswork using gauge barsor cobbled sections for setup

Superior resolution for precise guide setting and increased guide life and product quality

Calibration matched to Portable Optics system

Bench Optics Alignment Equipment



Optical Calibration

Care is taken to calibration match the bench and portable optics to ensure superior precision

Using the same mounting plates and alignment tooling the bench and portable optics are set to the exact same mechanical and optical centerline



Portable Optics Alignment Equipment

Unsurpassed finished product tolerances

Portable optics setting in the NTM Clamped on the X-clamp mounting system




Precise positioning of the roller entry guide bracket to the centerline of the roll groove

Used as a tool for checking roll cross indicating…Worn flingers in cantilevered mill standsIncorrect pass grinding or re-cutting in the mill rollsWorn tapered sleeves on cantilevered mill standsWorn thrust bearingsIncorrect mill roll mounting or positioning




Conditions of roll cross

If crossed rolls are found then proper corrective action procedures must be in place for the operators to make a determination when the billets should be rolled



Results: Maximum Guide Life

RE-20 guide rolling 5,5mm at 18,100ft/minute (92m/s)5,831 tons rolled

No changes to rollers or bearingsCampaign completed with no guide changes



Specialized Guide Topics

Multi-strand Slit Rolling of RebarsThe dividing of the billet into 2,3, or 4 bars for the production of multiple finished products in a single strand rolling mill

This is done by using a forming pass design to define to areas of the individual finished strands and “slitting” the bar using slitting delivery guides or powered slitting machine



Multi-strand slit rolling of rebars

Powered slitting machine 3-Strand Slitting guide on the Bench Optics



Increased production for smaller finished diameters

10mm Rebar

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Finishing Speed (m/s)

Rolli

ng R

ate

(mt/h

)

1 x 10mm

2 x 10mm

3 x 10mm

4 x 10mm

Multi-strand Slit Rolling of Rebars



Slit rolling pass sequence example




Slit rolling pass sequence example




Higher production of small rebar can be achieved without large capital equipment expenditures

The rolling mill can be operated to its full design capacity for the entire product mix

The product mix can be expanded to small sizes that were not cost effective to produce via conventional rolling methods

Can be easily applied to most bar mill configurations




Siemens VAI Guides

Guides for all mill types....

Recent Guiding Projects:POMINI Rod and bar mills worldwideMORGAN High speed rod mills worldwideASHLOW High speed rod mills worldwide

SMS Rod mill in Saudi ArabiaDEMAG Bar mill in Saudi ArabiaSIMAC Rod and bar mill in EgyptNKK Bar mill in EgyptDANIELI Flexi mill in Saudi ArabiaSKET Rod mill in UkraineVAI Bar mill in Kuwait

Thank You for your time and attention

India)

Documents

guide failures page

basics of rolling

guide supplier

alignment page

fixed restbars guide

sound rolling practice

requirements page

premature guide failures