Internship Project-Based Report on

STUDY OF MECHANICAL MAINTENANCE OF MILL STANDS AND

SHEARS IN STM

A Report submitted as a part of the training in Structural Mills

Visakhapatnam Steel Plant

RASHTRIYA ISPAT NIGAM LIMITED

(Duration:3rd June 2023 to 29th June 2023)

This Project is submitted by

Name Trainee Number

Vissapragada Aditya 100024237

V L V Sai Kiran 100024236

Under the guidance of C. BHAGAT SINGH , Dy. General Manager (Mech), STM

1
 CERTIFICATE

This is to certified that VISSAPRAGADA ADITYA (Trainee No:

100024237), V.L.V SAI KIRAN (Trainee No: 100024236) are 3rd year
students of B. Tech in Mechanical Engineering from SCSVMV
UNIVERSITY has completed the mini project work entitled
“STUDY OF MECHANICAL MAINTAINENCE OF MILLS STANDS
AND SHEARS” at Visakhapatnam Steel Plant, in “STRUCTURAL
MILL(STM)” department, in partial fulfilment of their training in this
organization under my supervision and guidance, during their training period.

Date:
Place:
Signature of Guide

C. BHAGAT SINGH
Dy. General Manager (Mech)
Structural Mills (Dept.)
Visakhapatnam Steel Plant

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 ACKNOWLEDGEMENT

We would like to thank RINL-Visakhapatnam steel for giving us such a

wonderful opportunity and providing us such a conducive atmosphere to gain
experience and enhance our practical knowledge. This project required a lot of
guidance and assistance from many people hence I am incredibly privileged to
have got this all along with the completion of our project with immense pleasure,
deep gratitude and respect.

We wish to express our sincere thanks to our supervisor, Mr. C. Bhagat Singh,
DGM(Mech)STM, RINL- VSP. Throughout the training period he was very
supportive and caring which led to the timely completion of the project. We are
incredibly thankful to him for providing such a support and guidance.

We would like to thanks to our guide, Mr. D. Aswin Ramchandra, (Assistant

guide) Mechanical.

We like to convey our sincere thanks to entire management/employees of STM

who helped us to compete this project. This project could not have been done
without resources, knowledge and valuable inputs that we received.

We would like to thanks our Head of the Department Dr. P. Vithya Senthil M.E,
(Ph.D.), Department of the Mechanical Engineering.

ABSTRACT

This project describes about the Over View of the Visakhapatnam Steel Plant, i.e.,
about the major departments present in it and what are the functions of them and
Various types of Maintenance that we perform in Structural Mill in Visakhapatnam
3
Steel Plant and what are the required parts to run the Mill stands and Shear, its
Identification of Problems, and coming up with the Remedies for the problems that are
identified. The mechanical maintenance of mill stands and shears plays a crucial role
in ensuring the efficient operation and productivity of steel plants. The key aspects of
mechanical maintenance strategies employed for mill stands and shears in steel plants,
focusing on the maintenance activities performed, their significance, and the benefits
they provide.

Firstly, the importance of mill stands and shears in the steel production process. Mill
stands are vital equipment used for the rolling and shaping of steel products, while shears
are responsible for cutting the steel into desired lengths. The uninterrupted operation of
mill stands and shears is vital for achieving high-quality output, meeting production
targets, and ensuring worker safety.

Next, the main maintenance activities carried out on mill stands and shears. These
include routine inspections, lubrication, alignment checks, wear and tear analysis, and
preventive and corrective maintenance. The significance of regular inspections to
identify potential issues and the importance of proper lubrication to reduce friction and
prevent component failures. Additionally, it highlights the necessity of alignment checks
to maintain accurate product dimensions and the significance of timely corrective
maintenance to minimize downtime and maximize productivity. Proper maintenance of
mill stands and shears leads to increased equipment lifespan, reduced breakdowns,
enhanced production efficiency, improved product quality, and a safer working
environment. By implementing preventive maintenance practices, steel plants can
minimize unplanned downtime, optimize maintenance costs, and achieve higher overall
equipment effectiveness.

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 CONTENTS

CHAPTER 1: INTRODUCTION TO VSP

1.1 Overview
1.2 Modern technology used
1.3 Raw materials
1.4 Departments in plant

CHAPTER 2: STRUCTURAL MILLS (STM)

2.1 Introduction to STM
2.2 Lay out Sequence of STM

CHAPTER 3: MILL PROPER

3.1 Reheating furnace exit are
3.2 Static water descaler
3.3 Pendulum shear
3.4 Rough mill Train
3.5 Crank Shear
3.6 Intermittent mill Train
3.7 Rotary Shear
3.8 Finishing mill Train
3.9 Dividing Shear

CHAPTER 4: FINISHINGLINE
4.1 Roller table
4.2 Lateral diverter
4.3 Cold saw for sample cut
4.4 Cooling bed
4.5 Multistrand straightening machine
4.6 Metal tag embossing

CHAPTER 5: ROLL SHOP

5.1 Introduction
5.2Cartridge
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 5.3Guide Rolls

CHAPTER 6: MAINTENANCE
6.1 Insertion unit
6.2 Hydraulic system
6.3 Set-up & Production change
6.4 Change of rolling groove
6.5 Adjustment of roll gap
6.6 Start-up use & stop
6.7 Preventive maintenance

CHAPTER 7: CRANES
7.1 EOT Cranes
7.2 Semi-Portal cranes
7.3 Jib cranes

CHAPTER 8: CONCLUSION

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 7

CHAPTER 1

INTRODUCTION TO VSP

1.1 OVERVIEW:

Steel comprises one of the most important inputs in all sectors of economy.
Steel industry is both a basic and a core industry. The economy of any nation
depends on a strong base of Iron and steel industry in that country. History
has shown that countries having a strong potentiality of Iron and Steel
production have played a prominent role in the advancement of civilization
in the world. Steel is such a versatile commodity that every object we see in
our day-to-day life has used steel either directly or indirectly. To mention
few, it is used for such a small item as nails, pins, needles etc. through
surgical instruments, agricultural implements, boilers, ships, railway
materials, automobile part etc., to heavy machines, structures etc. The great
investment that has gone into fundamental research in Iron and steel
technology has helped both directly and indirectly many modern fields of
today’s science and technology. It would seem very painful to imagine the
fate today’s civilization had steel not been there.

BACKGROUND:

Rashtriya Ispat Nigam Limited, the corporate entity of Visakhapatnam Steel

Plant is a Navaratna PSE under the Ministry of Steel. Visakhapatnam Steel
Plant fondly called Vizag steel. It is the first shore based Integrated Steel
Plant in the country and is known for its quality products delighting the
customers. It is a market leader in long products and it caters to the needs of
diverse Industrial sectors. It is the first Steel plant to be certified ISO
9001:2008 (presently2015), ISO 14001:2004 (presently2015), OHSAS
18001:2007 and ISO/IEC 27001:2013 Standards. It is also the first PSE to
be certified
ISO 50001:2011 - Energy Management Systems and has acquired CMMI
Level 3 Certification for s/w development. RINL's Visakhapatnam steel
plant, has an annual capacity of about 7.3 million tons. RINL’s existing
 facilities include a steel plant with 7.3 million tons per annum (Mt pa)
capacity, and a forged wheel unit in Uttar Pradesh with annual installed
capacity of 100,000 units. In FY23, crude steel production was 4.2 Mt and
saleable steel was 4 Mt, which the company intends to ramp up to 5.25 Mt
and 5.04 Mt, respectively, in FY24. It possesses the state-of-the-art
technology and a strong well-trained manpower of around 15,000
employees. The organization is house of technology where international levels
of efficiency are being pursued in terms of productivity and specific energy consumption.

1.2 MODERN TECHNOLOGY USED IN THE PLANT:

Modern Technology has been adopted in many areas of production, some of them
for the first time in the country. They are as follow:
1.Selective crushing of coal.
2.7 meters tall coke ovens.
3.ry quenching of coke.
4.On ground blending of sinter base mix.
5.Conveyor charging and bell less top for blast furnace.
6. Cast house slag granulates for blast furnace.
7.100% continuous casting of gas expansion turbines for power generation utilizing
blast furnace top gas pressure.

1.3 RAW MATERIALS:

• Iron ore lumps and fines.
• BF lime stone
• SMS limestone
• BF dolomite
• SMS dolomite
• Manganese ore
• Medium coking coal (MCC)
•
1.4 MAJOR DEPARTMENTS IN VSP:
• COKE OVENS AND COAL CHEMICALS PLANT (CO & CCP).

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 • SINTER PLANT(SP)
• BLAST FURNACE(BF)
• STEEL MELT SHOP(SMS)
• ROLLING MILLS
• LIGHT AND MEDIUM MERCHANT MILL(LMMM)
• WIRE ROD MILL(WRM)
• MEDIUM MERCHAT AND STRUCTURAL MILL(MMSM)
• SPECIAL BAR MILL
• STRUCTURAL MILL
• ELECTRICAL REPAIR SHOP(ERS)

COKE OVENS AND COAL CHEMICALS PLANT (CO & CCP) :

Coal is converted into coke by heating the prepared coal blend charge in the
coke ovens in the absence of air at a temperature of 1000oC-1050oC for a period
of 16/19 hours. The volatile matter of coal liberated during carbonization is
collected in gas collecting mains in the form of raw coke oven gas passing
through stand pipes and direct contact cooling with ammonia liquor spray. The
gas cooled from 800oC to 80oC is drawn to Coal Chemical Plant by Exhauster.
The residual coke is pushed out of the oven by pusher car through a guide into
coke bucket. The red-hot coke is taken to coke dry cooling plant for cooling.

9
The main by-product in the process of coke making is crude coke oven gas
and this has a lot of valuable chemicals. Coal Chemical Plant Recovers
Ammonia (NH3), Tar and Benzol from CO-Gas. The primary by-products
from Crude CO Gas are Ammonium Sulphate (NH4)2SO4, Crude Tar, Crude
Benzol and cleaned coke oven gas. The cooled coke from CDCP (Coke Dry
Cooling Plant) is separated into 3 fractions, BF Coke i.e., +25-70 mm, which
is sent to Blast Furnaces, Coke Breeze i.e., +0-15 mm, which is sent to Sinter
making and nut coke i.e., +15-25 mm, which is also used in the Blast Furnaces.
Facilities
• There are 5 batteries, each having 67 ovens.
• The volumetric capacity of each oven is 41.6 m3.
• Dry Coal charge/Oven is 32 tons.
• Salient Features
• Largest and technologically unique Coke Oven Batteries in the country
at the time of commissioning
• 7-meter-tall coke ovens batteries.
• 100% Dry Quenching of coke using Nitrogen gas.
• Power generation, from the waste heat recovered, at BPTS (Back
Pressure Turbine Station).

Capacity
• Production capacity (for 5 batteries) – 3.700Mt of BF coke per annum.

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SINTER PLANT (SP)

Sintering is an agglomeration process of fine mineral particles into a

porous mass by incipient fusion caused by heat produced by combustion
within the mass itself. Iron ore fines, coke breeze, limestone and dolomite
along with recycled metallurgical wastes are converted into agglomerated
mass at the Sinter Plant, which forms 70-80% of iron bearing charge in
the Blast Furnace. The vertical speed of sintering depends on the suction
that is created under the grate. At VSP, two exhausters are provided for
each machine to create a suction of 1500-1600 mm water column under
the grate.

Provisions
• Sinter machine-1 with 378 M2 grate area (after Modernization)
• Sinter machine-2 with 312 M2 grate area.
• Sinter Machine-3 with 408 M2 grate area.

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Salient Features
• Base mix (homogeneous mixture of all raw materials) blending yard with
six beds each of 1, 10,000 tons storage capacity.
M/C-1&2
• Sinter Machine-1 (after modernization) is provided with Chamber type
Ignition Furnace with roof mounted energy efficient burners. Machine-2 is
provided with an ignition furnace of horizontal burners.
• Sinter Bed Height 650 mm for M/C-1 (after Modernization) & 500 mm for
M/C-
2.
• Straight Line Sinter Cooler. Sinter Heat Recovery Power Plant (SHRPP)
with a capacity of 20.6 MW electrical power generation by utilizing waste
heat recovered from Sinter Coolers of Machine 1 & 2
M/C-3
• Bed Height 700 mm.
• Chamber type Ignition Furnace with roof mounted energy efficient burners.
• 27 m long extended hood with hot air supply through 4 feed points.
• Circular Sinter cooler with waste heat recovery system.
• Lime addition at Mixing and Nodulizing Section of Sinter Machine
building.

Capacity
• Sinter Machine - 1: 3.640 MT of Gross Sinter per annum (after
Modernization)
• Sinter Machine – 2: 2.85 MT of Gross Sinter per annum.
• Sinter Machine – 3: 3.611 MT of Gross Sinter per annum.

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BLAST FURNACE (BF)

Iron is produced in the Blast Furnace by smelting iron bearing

materials with the help of coke and air. The solid charge materials like
sinter, sized iron ore, coke etc. are charged in the vertical shaft of the
Blast Furnace from top and hot air blast is blown through tuyeres
located at the bottom. The oxygen present in hot air combines with the
carbon of coke and generates heat and carbon monoxide (reducing
agent). The reducing gases, while ascending upwards comes into
contact with the descending charge materials. Eventually the charge
gets reduced and hot metal, slag and BF gas are produced. Hot metal
and slag are tapped from tap hole. The Blast Furnace gas which comes
out from top of the furnace is cleaned and used as fuel in the plant.

Facilities
• Three Blast Furnaces of 3800 m3 useful volume each.

Salient Features
BF-1 & 2
• New generation Paul-Wurth "Bell-Less" Top with conveyor charging • BF
Cooling elements (Cast Iron Staves & Copper Staves)
• High heat zone copper staves.

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• Double compensator tuyeres, with PCI injection facility and extended
tuyere platform.
• Circular type flat cast house with full castable runner system
• Hydraulic Drilling Machine, Mud Gun, Manipulators.
• Silencer to bin pressure relief.
• New scrubber with annular gap element for better gas cleaning.
• HMI based control room.
• Equipped with above burden temperature Probes.
• Automation with PLC in BF-1 and PCS in BF-2.
• Pulverized Coal Injection system

BF-3
• New Generation Parallel Hopper Bell Less Top • BF Cooling elements
(Cast Iron Staves & Copper Staves)
• Flat Cast house Equipment (by TMT).
• INBA Slag Granulation system
• Annular Gap Scrubber
• Pulverized Coal Injection system
• Hot Stoves (internal combustion chamber)
• Automation with DCS Capacity

• Production Capacity - 7.5 MT per Annum for shop

- 2.5 MT per Annum for BF-1, 2 & 3 each

STEEL MELT SHOP (SMS) &CONTINUOUS CASTING:

Steel is made in steel melting shop in the refractory lined vessels called
LD Converters by blowing oxygen through the hot metal bath. While
iron making is a reduction process, steel making is an oxidation
process. The oxygen reacts with impurities like carbon, silicon,
phosphorous, Sulphur etc. present in hot metal to produce steel. No
external fuel is required as the silicon & carbon releases huge amount
14
 of heat energy. Also, the carbon reaction releases large quantities of gas
rich in carbon monoxide along with huge amount of dust. The gases
released from the converter are collected, cooled, cleaned and
recovered for use as fuel in the steel plant. The entire molten steel at
VSP is continuously cast at the radial type continuous casting machines
resulting in significant energy conservation and better-quality steel.
100% Continuous casting on such a large scale has been conceived for
the first time in India.

Facilities
SMS-1:
• Three LD converters (modernized with increase in volume to 150 cum. each
along with DOG House facility).
• 6 nos. of 4 - Strand Continuous Bloom Casting machines. SMS-2:
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 • Three LD Converters of 150 cum. volume each.
• 1 no. of 6- Strand Continuous Billet- cum- round caster.
• 2 nos. of 6- Strand Continuous Billet casters.
• 1 no. of 5-strand Continuous Billet-cum-round caster.
• Hot Metal Desulphurization Plant (HMDP).
• DOG House.
• RH Degasser.

Salient Features
• 100% Continuous casting of steel.
• Converters gas cooling, cleaning and recovery systems.
• Computerization of the converter process.

Capacity
Production Capacity
• SMS-1: Original Installed Capacity is 3.0 MT of Liquid Steel per annum & 2.82 MT
of CC Blooms per annum. After Modernization of all the 3 converters, capacity is
enhanced to 3.5 MT of Liquid Steel & 3.29 MT of CC Blooms per annum.
• SMS-2: 3.8 MT of Liquid Steel per annum & 3.7 MT of CC Blooms/Rounds per
annum from Converters-D, E & F.

LIGHT AND MEDIUM MERCHANT MILL(LMMM)

The cast blooms from continuous casting department are heated and rolled in the two
high speed and fully automated rolling mills namely Light & Medium Merchant Mill
(LMMM) and Medium Merchant & Structural Mill (MMSM). The billets produced in
LMMM are further rolled in Bar Mill/Wire Rod Mill (WRM). The finished products
include wire rods & long products like reinforcement bars, rounds, squares, flats,
angles, channels, billets etc. Blooms from Continuous Casting Division are rolled into
billets, some of which are sold and rest are sent to Bar Mill/WRM. The continuous two-
line Bar Mill comprises of 8 Stand Double Strand roughing train, 2 nos. of 4 Stand
Single Strand intermediate train & 2 nos. of 4 Stand Single Strand finishing train.
Lopper are provided in between
the finishing stands for tension free rolling in order to obtain good surface quality and
tolerances. Housings are of closed top type. Roll necks are mounted in anti-friction
bearings.

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Facilities
Breakdown Mill
• 7 Stand Break-Down
Mill. Bar Mill
• 8 Stand Roughing Mill (2 Strand rolling).
• 2X4 Stand Intermediate Mill (Single Strand rolling).
• 2X4 Stand Finishing Mill (Single Strand rolling).

Salient Features
• Evaporating cooling systems in Rolling Mill furnaces.
• Computerized Rolling Mill.
• Temporal cooling process facilitating high strength with good bendability and
weldability.

Capacity
• A Mill of 0.88 MT per annum.
•
WIRE ROD MILL (WRM)

WRM-1: The Mill is high speed 4 strand No-Twist continuous mill designed to
produce 8,50,000 Tons of wire rod coils per year. Rolled billets of 125 mm x 125 mm
square cross section, length ranging from 9.8 m to 10.4 m and
weighing approximately 1250 kgs are used. The mill is designed to roll steel stock of
0.9% max. carbon content.
 WRM-2:

The Mill is designed to produce 6,00,000 tons per year of rounds in coil form. The Mill
is designed to roll low, medium and high carbon steel, case hardening steel, cold
heading quality steel, electrode steel, spring steel, bearing steel and free cutting steel.
The mill shall use continuous cast billets of 150 mm X 150 mm square cross section,
12 m length and weighing 2100 kgs approximately, are used as input material.

Facilities
WRM-1
• 7 Stand Roughing Mill (4 Strand rolling).
• 6 Stand Intermediate Mill (4 Strand rolling).
• 4X2 Stand Pre-finishing Mill (Single Strand rolling).
• 4X10 Stand Finishing Mill (MORGAN BLOCK-Single Strand rolling).
•
WRM-2
• 6 - Stand Single strand Fast Roughing Mill.
• 2 - Strand insulated Roller Table.
• 6 Stand Intermediate Mill - I.
• 4 Stand Intermediate Mill - II.
• 2 x 2 pre-finishing train.
• 2 x 8 - Stand No-Twist blocks.
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 • 2 x 4 - Stand Reducing and Sizing Mill (RSM).

Salient Features
• Highly automated and computerized Rolling Mill.
• Controlled cooling of Wire Rods, by 'Stemler' process with Opti mesh technology giving
high strength and good ductility.
• Closed loop control for Laying temperature with Morgan patented METCS (Morgan
enhanced temperature control system) in WRM-2 to enhance Metallurgical properties.

Capacity
• WRM-1: 1.050 MT per annum.
• WRM-2: 0.60 MT per annum.

Product-Mix
WRM-1
• Plain Rod - 5.5 mm to 12.7 mm diameter. However, sizes up to 14 mm are also being rolled
presently.
• Rebar - 8mm, 10mm and 12mm diameter in coil form. WRM-2
• Plain Rod - 5.5 to 20.0 mm in step of 0.5, Plain rod Día 20.64 mm can also be rolled in
future.

MEDIUM MERCHAT AND STRUCTURAL MILL(MMSM)

The Medium Merchant and Structural Mill (MMSM) is one of the modern rolling mills of
Visakhapatnam Steel Plant. This is a single strand continuous mill having production capacity
of 8,50,000 tons per year. The important feature of this mill is that Universal beams (both
parallel and wide flange) have been rolled for the first time in India using Universal stands.
Parallel flange beams have an advantage over conventional beams because, for the same
weight, the section is stronger and stiffer due to greater moment of inertia and higher radius of
gyration.

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Facilities
• 8 Stand Roughing Mill.
• 6 Stand Intermediate Mill.
• 6 Stand Finishing Mill.
Salient Features
• Evaporating cooling systems in Rolling Mill furnaces.
• Sophisticated, high speed rolling mills with computerized controls.
Capacity
• A Mill of 1.070 MT per annum.
SPECIAL BAR MILL

The Mill is designed to produce 7,50,000 tons per year of plain rounds in straight
length and in coil form by using an input of Continuous cast billets of 150 mm x 150
mm x 12 m and weighing approximately 2050 kgs. The mill is designed to roll
medium and high carbon steel, case hardening steel, cold heading quality steel,
electrode steel, spring steel, bearing steel and free cutting steel.

Facilities
• 6 Stand Roughing Train.
• 6 Stand Intermediate Train.
• 6 Stand Pre-Finishing Train.
• 3 Nos. Stand Finishing Train (Sizing train).
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 • Pendulum shear, flying shear 3and dividing shear.
• Controlled cooling facilities.
• Straight Form: Chain transfers, Cold Shear, Bundling Facilities and Strapping
machines.
• Coil Form: Garret coilers, Cooling conveyors, Hook conveyors, Compacting
and Strapping Machines.
Salient Features
• Continuous Mill consisting of 21 stands of housing-less design.
• 20 - 45 mm size in str
• Free size rolling (Customized sizes with closed tolerances).
• Low temperature rolling for finer grain structure.
• Online automatic measuring gauge for better quality control.
• Automatic bar Bundling & Strapping machines for packaging of finished
products.
Capacity
• 0.75 MT per annum. The enhanced production capacity is 0.90 MT per annum.

Product-Mix
Round Form Outputs:
• Rounds - 20 mm to 45 mm diameter (with a special provision to roll 16 mm
to 18 mm).
• Coils - 2.0 tons (as per billet weight).

Straight Form Outputs:

• Straights - 12.0 m bundle with 6 straps.
• light & coil form (Reduced wastage for end user).

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 CHAPTER 2

2.1 INTRODUCTION OF STRUCTURAL M I L L S

The Structural Mill has been built as part of the expansion program of
Visakhapatnam Steel Plant to increase its production to 6.3 mtpa. The mill is
designed to produce 7 lakh tons of structural and merchant steel products per
annum. The rolling mill plant has been set up with a continuously rolling mill
train provided with two finishing facilities for straight sections. The
technology and equipment supplier for the mill is Daniel, Italy.

CHARACTERISTICTS:

The high quality of the final product in terms of very strict tolerance and material
quality is constant characteristic of the rolling mill. This objective is achieved with
the help of:
O Fixed rolling axis along the rolling train (no rolled stock deviation): -
• Torsion free of the roll stock in the pre-finished mill due to H-V alternatively
arranged stands. Minimum tension control and tension free (loop) control.

• Use of the well proven technology of Morgardshammar guides and rolling

know-how, all over the mill.
• Cartridge type stands designed with maximum sturdiness to withstand heavy
rolling loads (roughing/intermediate and finishing mill).

• Start/stop type flying shears along the mill for cropping (or emergency chopping)
of the rolled stock
• Level 2 automation for furnace and mill including yard management system
Hi- Profile for continuous measurement of dimensions of hot rolled products.
• Hi-Straight for checking straightness and torsion of bars coming out from
straightening
machine.
• Use of cast basalt liner in scale flume tunnel of mill.
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 • Beside the single section quality itself, we consider very important also the
quality of the bundles of bars and stacks of profiles regarding the shape,
section alignment, number of sections and quality of ties. The proposed
finishing services are designed with the abovementioned purpose.
Besides the high productivity of the plant and the constant high quality of the
final product, we take into consideration also the economic objectives like:

Short time to set-up the mill for the production charging due to the roll pass design, the
stand design, the stand charging system of the stands, the operational equipment in the
workshop and to the automation system of the rolling mill. High mill utilization factor.

ROLLING MILL NOMINAL CAPACITY: -

700,000 tpy of structural sections in straight length within 3,733 rolling hours and
850,000 tpy of sections in straight length within 4,533 rolling hours.

RAW MATERIAL:
Continuously cast cold bloom 200x200x12,000 mm, weight 3,670 kg

FINAL PRODUCTS:

Beams: ISMB 100, 125, 150 mm

23
 ISJB 150, 175 mm

Channels: ISLB 100, 125, 150 mm

ISMC 75, 100, 125, 150, 175 mm

ISJC100, 125, 150, 175 mm

ISLC 100, 125, 150 mm

Equal Angles: 55 to 100 mm (thickness 5 to 12mm)

Special sections:
Rounds 45 to 95mm

Squares 45 to 80mm

HE columns with parallel flanges 100 to 120mm

(DIN 1025-5 standard)

IPN Beams with tapered flanges 100 to 180 mm

(DIN 1025-1 standard)

IPE Beams with parallel flanges (DIN 1025-5 standard) 100 to 180 mm
Tee 60X60X7mm

24
Mill Stand
25
 Block diagram of Mill Stand

Annual
production

Total production 700,000-850,000(TPY)

Calendar days 365

26
 Weekly shutdown 52
days
Capital shutdown 13
days
Operating days 300

No. of operating 3
shifts per day

Total operating 7200

hours/year

2.2 LAYOUT & SEQUENCE OF THE ROLLING PROCESS:

Use of continuous cast blooms

Extenuate (200X200 X12000mm)

Bloom Charging on the Pawl Transfer

Weighing of bloom in weighing machine

Charging of bloom in the Reheating Furnace

Bloom Re-heated in the 200 TPH walking beam type furnace

Discharging from the Furnace

27
 Pinch roll and water descaler

Emergency cutting of bloom

Rolling in the 7-Stands Roughing Mill (7 Housing less Stands H and V-axis
configuration) **

Head/Tail section cropping and emergency section chopping in Crank Shear

Rolling in the 5-Stands Intermediate mill (5 Housing less Stands H, H-V-U, H-

U configuration) **

Cut to multiple length with a dividing shear at finishing mill exit side

Hi-Profile for checking profile

Diversion to Double finishing line by diverter

Section cooling and transfer in cooling bed

Section straightening in multistrand straightener and straightness checking by Hi-

STRAIGHT

28
 Temporary collection of rolled section in batching table
Layer forming and cutting to final length with Metallic saws

Section stacking with stacking stations

Section strapping with Strapping machines

Section weighing and collecting in collecting stations** H - Horizontal, V - Vertical, U

-Universal

STEEL GRADES

The steel grades rolled are: IS 15 2830, EN8, SAE 1524, SAE 1020, SAE 1030,
37C15, SAE 1008,
SAE 1010, SAE 1015, etc.

ESTIMATED OPERATING TIME CALCULATION

Total operating hours 7200

Mis-Rolling and other hours/year

operational delays

900

5600

29
 SPECIFIC CONSUMPTION:
Indicative values for producing 1 ton of finished product:

Rolls & rings (cast iron rolls for stands) 480-700 g/ton

Rings for Straightener (each) 115

Guides (wearing parts) 20-22 g/ton

Shear blades 30 g/ton

Fluids: lubricants 85 g/ton

Electric energy: Structural mill technological 177.3 KWh/ton

area only

MILL UTILISATION FACTOR:

Assuming the planned operating time of 7200 hours per year and the
total rolling time of 4533 hours per year (for 850,000 tpy): Mill
Utilization Factor =Rolling time/Available time
= 4533 hours/7200 hours
=62.96%

30
 CHAPTER 3

MILL PROPER
The rolling mill performs the rolling process in order to obtain the rolled product
with the requested size and metallurgical properties.

3.1 REHEATING FURNANCE EXIT AREA:

This area transfers the hot billets coming from the reheating furnace to the roughing
stands. It consists of the following equipment:
Static water
descaler
Roller table with
hood
Pendulum shear
Disappearing
stopper
Emergency
bench

3.2 STATIC WATER DESCALER:

The high-pressure water descaler, located just after the furnace exit door, is used to
remove scales formed on the surface of the bloom during heating inside the furnace.
The descaling is necessary for smooth rolling and is done by directing high pressure
water on to the bloom. The descaler consists of an enclosed steel box structure. The
closed housing contains four spray-bars for the four sides of the bloom.
The top part is easily removable by crane for maintenance purpose. Chains are
installed at entry and exit side to prevent water spraying from the box. The bottom
part is shaped for easy water discharge into the flume.
The following are some important parameters of the
descaler Descaling speed : 1.0 m/s
27approx.
Working pressure : 200 bars

31
Water working flowrate : 400
l/min Number of nozzles :
15
A separate high-pressure water pump station is installed to cater to the descaler. It
has three piston- type pumps: two working and one on stand-by. At every new start
of the booster station, the standby pump changes. Each pump has a capacity of 13
m3/h.

FURNACE EXIT SIDE ROLLER TABLE:

The roller table at the furnace exit has retaining hoods to prevent heat loss from
bloom. Heat retari hoods are provided to reduce the temperature difference between
head and tail of the incoming material. The insulating material is ceramic fibre.

EMERGENCY DISCHARGE TABLE:

In case of mill stoppage, the blooms that have been discharged from the furnace and
are on the roller tables, can be discharged onto the emergency reject table. The
bloom reject table consists of a set of lifting/lowering ejection levers, which are
mounted onto a common shaft and actuated by two hydraulic cylinders. The rejected
blooms can then be removed with the help of overhead cranes or forklift.

32
DISAPPERING STOPPER:

It is located at the end of the furnace exit roller table and is used to stop the bloom in case
the roughing mill is not ready to roll. This is to prevent any further billet from entering the
downstream area. It also lifts whenever the mill stops. It is actuated by one pneumatic
cylinder.

3.3 PENDULUMN SHEAR: (SHEAR 0)

The pendulum shear is used for emergency chopping in case a problem occurs along
the downstream rolling mill area, such as a cobble or 'mill not ready conditions. It is
located at rolling mill entry.
The shear uses a lower blade fixed to the pendulum frame and mobile upper blade driven
by a pair of motors through reduction gears, an eccentric crank and connecting rod to
perform bar cutting
As a safety measure, the shear is installed in a caged house.
A wheeled unit for collecting crops is provided underneath the shear. It consists of a
railmounted transfer car with a scrap bucket standing over.
Cutting operation is carried out by the pendulum blade group with a blade movement
tangent to the bloom.
It has a cutting force of 3300 Kn and consists of a set of upper and
lower blades. A blade-changing trolley is provided for easy
removal/fixing of shear blades.

33
ROLLING MILL:
The mill consists of 17 rolling stands divided into three mill trains: Roughing,
Intermediate and Finishing.

3.4 ROUGHING MILL TRAIN:

The Roughing Mill stand consists of the first 7 stands of the mill, located between
the pendulum shear and the crank shear.

3.5 CRANK SHEAR: (SHEAR 1)

The crank shear is located after stand 7, the end of the roughing mill train. It is a
START-STOP Crank Type CVSB 125 Shear with two blades, one blade mounted on
each blade holder. It can perform the following functions: head cropping. tail
cropping and emergency chopping
One flywheel is mounted onto the entry shaft of the shear-gear. It is connectable to
the entry shaft
by means of a manual lever. It can be connected to system only in the low-speed
range.
A mechanical "through' is installed on the entry side of the shear to guide the
entering bar into the shear blades. The shear is enclosed in a safety guard house. It
is powered by start-stop motor and the gear is driven to blade holder shafts.
Cutting force: 125 t
Tail Extraction Device: Rolls for tail extraction are located on the shear inlet
through. This unit serves as a tail extractor when the shear is in chopping mode and
the billet leaves the upstream stand.

34
3.6 INTERMEDIATE MILL TRAIN:
The Intermediate Mill stand consists of 5 stands of the mill, located between the
crank shear and the rotary shear.

3.7 ROTARY SHEAR: (SHEAR 2)

The rotary shear is located after stand #12, the end of the intermediate mill. It is a
double blade type shear which can perform head and tail cropping as well as
emergency chopping. Its cutting force is 60
t. It has two blades on each of the two blade holders.
The shear is driven by one main AC motor coupled to the shear entry shaft. Two
flywheels are mounted onto the entry shaft of the shear-gear. Each flywheel is
connectable to the entry shaft by means of a manual lever. Both flywheels can be
connected to system only in the low-speed range. One flywheel can be connected in
the intermediate speed range while none can used in the high-speed range.
Tail Extraction Roll: It is a pinch roll located on the shear inlet through. This unit
serves as a tail extractor when the shear is in chopping mode and the bloom leaves
the upstream stand.

35
3.8 FINISHING MILL TRAIN:
The Intermediate Mill stand consists of the last 5 stands of the mill, located between
the rotary shear and the dividing shear.

3.9 DIVIDING SHEAR: (SHEAR 3)

Pinch Roll: A pinch roll set is installed upstream the dividing shear which ensures a
constant bar speed for the full bar length and also in those conditions when the bar is no
longer driven by a mill stand. A constant bar speed ensures reproducible cutting lengths.
The upper roll is movable while the lower roll is fixed in order to close the bar. It is a
cantilever type pinch roll. The dividing shear is located at end of rolling mill. It cuts the
bar at a multiple of commercial length. It is a start-stop, combined type shear designed to
cover a wide rolling speed range. The shear has a double blade configuration, namely:
Crank movement - low speed
Rotary movement-high speed
The shear housing is shiftable horizontally to position one of the blade types to the centre-
line of the mill. The entire shear housing is enclosed in a steel cage for safety purposes.
The shear is powered by a start-stop motor and the gear is driven to blade holder shafts. A
flywheel is mounted onto the entry shaft of the shear-gear. It is connectable to the entry
36
shaft by means of a manual lever. It can be connected to system only in the low-speed
range.

HI-PROFILE GAUGE:
The Hi-PROFILE Gauge is a laser measuring device for shape and dimensional
inspection of hot rolled sections, directly on the production line without any physical
contact.
Mounted on a shiftable trolley, it is located downstream stand #17 and after the
dividing shear.

It main features are:

- High measurement accuracy
- Real-time display of shape and dimensions
- Network interface for automatic setup and reporting
-Profile defect inspection
- Defect analysis during the production process
- Quality certification reporting capabilities

37
 CHAPTER 4

FINISHING LINE :
The finishing facilities include two areas with the same configuration, known
as Line-1 and Line-2. Each area includes the following main equipment:
Roller tables with lifting
aprons Cooling bed
Straighteners
Layer
preparation
Cold cut area
Stackers
Tying and removal
area Storage area

COOLING BED AREA:

The inlet roller table is located between the dividing shear and the roller table
with aprons. Its function is bar conveying and acceleration.

DIVERTER:
A line diverter is installed at rolling mill exit in order to alternately convey the
bar to the cooling beds.
The diverters are inclined plates located at the bottom of conveying roller
table. These plates are normally at lower position. When the material must be
sent to a finishing line, the related plate moves up and the product slides over
the plate moving into selection direction.
A diverter flap is located at the end of diverter plates and move together with
the plates to guarantee that the product runs to the correct finishing line.

38
4.1 ROLLER TABLE WITH LIFITING APRON:
Downstream the diverter, a roller table is installed. It is equipped with a set of aprons
to brake and discharge the bar onto the cooling bed. Synchronization and control for
the roller table with aprons and cooling bed is provided in order to properly regulate
the cooling bed entry. Different speed references for the various roller table sections
are used to accelerate and physically separate the bars produced by the dividing cut.
Each bar is braked on the last part of the roller table and discharged onto the cooling
bed by activating the aprons. A shaft and levers group controlled by hydraulic
cylinders performs aprons lowering/lifting.

39
BAR EXPULSION FLAP:
The bars have the function to aid the sliding movement of the flats from the
roller table to
the aprons. The bar expulsion flaps move forward and reverse by pneumatic
cylinders individually controlled by a single coil two-positions solenoid valve.

4.2 LATERAL DIVERTER:

Its aim is to lift the incoming bar head to avoid interference with previous bar.
The effect obtained through this pneumatic device is to divert the head of the
arriving bar towards the external wall of the aprons, when the head is at the
level of the device itself.
The lateral diverter is moved forward and reverse by pneumatic cylinders
controlled by a single coil solenoid valve.

4.3COLD SAW FOR SAMPLE CUT

The saw is designed to make straight cuts across static bars. One saw is
installed at the side of each cooling bed in order to cut a sample from selected
bars. When sample cut is requested, a different cycle is performed by the
cooling bed area due to the fact that the saw is installed at the opposite side
with respect to aligning stopper on lining-up rolling table.
The disc is driven by an AC motor, which runs only in the forward direction
during the cutting cycle. The disk swinging movement toward the material is
performed by means of a hydraulic cylinder. A holding brake is provided for
the saw mechanism at the main motor exit drive shaft. The brake is not used
to stop the disk during the cutting cycle but used only to hold position.
Therefore, the brake is always ON when the motor is OFF.
A couple of booster pumps are installed to provide cooling water to the cutting
disc. During normal operations, one pump is running and the other is on stand-
by. At every new start of the booster station, the operating pump and stand-by
pump are switched. At the unit inlet, a filter is installed to remove impurity
from the water. Cyclically, the filter automation performs a self - cleaning
sequence.
The saw is provided with a safety cover that can be open/closed by a hydraulic
cylinder activated by a double solenoid valve.

40
4.4 COOLING BED:
The cooling bed consists of a set of frames-one fixed and the other mobile-
designed to contain and cool the bars cut to multiples of commercial size. The
bars are discharged onto the cooling bed by aprons.
The fixed frame supports the bars while the mobile frame which is driven by
a motor carries out an advancing cycle obtained by means of eccentrics on
which the mobile frame has been assembled.
A holding brake is provided at the main motor exit drive shaft coupling. It
consists of two shoes that lock and unlock the drive shaft. The brake is not
used to stop the motor during cooling bed cycle but only to hold position.
Cooling water system: in the middle of the cooling bed a set of sprays is
installed to deliver
water with pressure for bars cooling.
Lining Up Roller Table: at the cooling bed exit the bars are lined up by shaped
rollers before being facilitate operations downstream. Several cooling bed
steps, generally three, are necessary to transfer discharged. These rollers are
specially grooved for tidy lining-up of bars at one side of cooling bed to bars
from entry side of lining up rollers to downstream area.

41
The rolls are divided in groups to allow their exclusion depending on profile type
and profile weight. When working only with 1" section of cooling bed (slow cooling
products), the lining-up rolls are not used because the movable rake is continuously
running in order to transfer as fast as possible the bars to cooling bed exit area.
At every cooling bed step, the inserted rolls start their movement for a time set by
schedule on supervisor. The number of groups running is also set by schedule to
compensate the production profile weight (for heavy profiles more groups must be
inserted).

4.5 MULTISTRAND STRAIGHTENING MACHINE:

The straightener machine consists of five pairs of rolls, identified as upper rolls and
lower rolls. The upper rolls are motorized, the bottom rolls are idle.
The straightener is driven by an AC motor with a ventilation system suitable for this
application and fed by an AC inverter.

42
ROLLS ADJUSTMENT:
The straightening rolls adjustment is used to modify the shape of the straightening
curve and the straightening effect itself. Two types of roll adjustment are possible:
Axial and Vertical
Upper Rolls Axial Adjustment: The axial movement is applied to the upper
rolls. The - movement is made along the longitudinal roll axis direction.
Regarding the axial adjustment, only the movement from central position is
detected. It is intended to be positive for the right ended movement and
negative for the left ended movement. Rolls central position (0-position) is
also the rolls extraction position for rolls set change.
Lower Roll Vertical Adjustment: The vertical movement is applied on
motorized rolls. The movement is made along the vertical axis of the roll by
means of five double speed AC squirrel cage motors. Three values are
measured from vertical movement: Absolute, Relative and Deflection.
The Absolute Position A indicates the distance of the roll from the all-open position
(generally low position) and is always a positive number.
The Relative position G (Gap) indicates the gap between the lower and its
corresponding upper roll. A negative value means that there is no gap between the
bottom and top roll and these two are over-placed.
The Deflection Position D indicates how much the machine is bending the material.
A positive value means that the roll is working on the material while a negative
value indicates that the roll is too open to bend the bar and is therefore not working.
A value of zero indicates that the rollers are tangent to the bar and no pressure is
exerted.

ROOL CHANGING TOOL:

The rolls basket must be engaged to the spindles for straightening operations by the
roll changing tool.

SIDE WALL SHIFTING:

The side wall is driven by a hydraulic cylinder. The side wall is opened and closed
during the roll’s basket correctly. The straightener is equipped with a shiftable side
wall in order to extract the rolls change operation.

43
COBBLE DETECTION SYSTEM:
A pulled rope device is installed on the top and across of the straightener exit roller
table. It uses a proximity switch to detect any abnormal material bend. This avoids
any cobble damaging the machine.
The signal is used to stop all the machines involved on the straightening process.

BY-PASS ROLLER TABLE:

When the straightener is not required for the current production, the rolls pack can
be replaced by a roller table track that can be inserted inside the machine body. The
roller table includes two motorized rolls that are powered by a variable frequency
drive common with straightener exit roller table. The motor cabling includes a plug
that can be disconnected when the roller table must be removed.

4.6 METAL TAG EMBOSSING MACHINE:

Located in the bundle weighing area, it can emboss the following
information: Size
Material grade
Code heat number
'Packet/Bundle
number
Packet/Bundle
weight Date &
time
The metal tags have sufficient blank space for accommodating the non-tear able
plastic label.

LABELLING MACHINE:
It produces text, bar codes, 2D codes, logos, and graphics on adhesive, non-
tear able plastic labels. The label will be applied manually.

44
COLLECTING AREA:
The roller table in the collecting area has a disappearing dampened stop as well as
a fixed stop at the end. The finished product is removed from the roller table by the
chain transfer liftable arms and conveyed to the downstream collecting chain
transfer. The material is finally removed from here by overhead cranes and stacked
in the dispatch area.

45
YARD MANAGEMENT SYSTEM:
Magnetic cranes are equipped with Level-2 automation system which
communicates through Wi-Fi for identification of material lifted by crane. PCs are
installed in the crane operator's cabin enabling him to stack the material at correct
location. Mapping of stack is created by Level-2 automation system which helps the
operator while dispatching into wagon or trailer

46
 CHAPTER 5

5.1 ROLL SHOP: INTRODUCTION

The main activities of the Roll Shop are rolling pass design, grooving of rolls,
assembly and disassembly of rolls with bearings, cartridge preparation, and
servicing of guides and its parts. Rolling is affected in the rolling mill stands
by passing the material between the guides and grooves in top & bottom rolls
as per the Roll pass design. The guides and roll grooves tend to wear out in
service.
The grooves are reclaimed by redressing on Roll turning lathes.
The guide materials are reclaimed/repaired to the original shape and size.

ROLL SHOP FUCTIONS:

STM Roll shop caters to the mill requirements of:
Roll pass design, guide design, supply of roll assemblies, guide
assemblies and cartridge CNC technology has been adopted for
grooving of steel mill work rolls and guide rollers for achieving high
repetitive accuracy and higher productivity compared to conventional
ones Supply of Work Rolls with profiles cut in them for rolling of the
required products Supply of Guides required for all the products rolled
in the mill
Mounting of inner races, Labyrinth rings on to the Roll necks
Supply of Prepared Cartridge to the Rolling mill Area as per
requirement Roll shop consists of different sections. They are:
Roll turning area
Guide assembly area/guide repair
area Cartridge preparation area.

ROLL TURNING AREA:

The basic function is to turn the grooves on the work roll and
Straightener Rolls barrel as per the roll pass groove drawings and CNC
programs according to the rolling requirements. There-after
returning/redressing of these rolls at frequent intervals depending on
their usage and service in the mill.

47
 Blank Rolls are procured from the roll manufacturers as per
specification given by the mill builder. The Roll materials can be
broadly divided into two types i.e.
Alloy Cast Steel rolls for Stands 1 to 3
Alloy Cast Iron rolls for Stands 4 to 17
A Roll-Management system is in place for monitoring the
circulation/usage and performance of the Rolls.
The major equipment in roll turning area is:
.
• CNC ROLL TURNING LATHE
• CNC UNIVERSAL MILLING MACHINE
• CNC ELECTRO DISCHARGE WIRE CUT MACHINE
• ROLL BRANDING MACHINE
• CNC GUIDE ROLL TURNING LATHE
• RADIAL DRILLING MACHINE
• SHAPING MACHINE
• CONVENTIONAL LATHE
• VERTICAL HYDRAULIC PRESS
• DOUBLE HEAD PEDESTAL GRINDER
• GUIDE ASSEMBLY & BEARING SHOP AREA • HIGH PRESSURE JET
• ULTRASONIC BEARING CLEANING DEVICE
• UNIVERSAL HYDRAULIC PULLER JET
• BEARING INNER RING INDUCTION HEATER

5.2 CATRIDGE PREPARATION:

CATRIDGES:

Equipment Use Quantity

Cartridge GCC 7555 #1 to #3 Stands 8
Cartridge GCC 6548 #4 to #17 stands 35
Cartridge GUC 8548 Universal stands 14
Robots Cartridge 3
preparation

48
SPECIAL FEATURES IN CATRIDGES
Hydro motor is used for roll gap adjustment (Single
Motor) Digital display of roll gap
Zero setting after pressing top and bottom rolls touching against each other
which takes care of cassette spring and gives exact required stock size instead
of different spring in different cartridges.
Manual measurement is eliminated
Automatic gap setting in mill area (considering roll gap and roll
diameter) Washing equipment along with transfer car
Fixed beams provided in the
mill System is very rigid
No provision for beam height adjustment which prevents manual error of
setting the height Flexibility in cassette management due to presence of
containers Roll balancing by spring system Indication for axial height

STAND TILTING MACHINE:

Stand tilter provides the rotation of cartridge stand from horizontal to vertical
position and vice versa. Stand tilter rotation is performed by hydraulic motor.
One stand tilting machine is installed in cartridge preparation area and second
machine is installed in mill area.

TRANSFER CAR:
Cartridge transfer cars are 3 in number with two equipped with hot water washing
facility for cartridge.

49
Generally, transfer cars are used to transport cartridge from roll shop area to
mill area. Guides and rolls can also be transferred.

5.3 GUIDES & ROLLS:

The total number of rolls available: 1414, in two types:
Plain Rolls: 670, with the following breakup:
GCC 6548 Plain Rolls 60
GCC 8548 Horizontal Plain Rolls 200
GUC 8548 Vertical Plain Rolls 390

Grooved Rolls: 744, with the

following breakup GCC 7555
Grooved Rolls 22 GCC 6548
Grooved Rolls 506
GUC 8548 Horizontal Grooved Rolls 108
GUC 8548 Vertical Grooved Rolls 08

ROLLER GUIDE RACKS:

These racks are used for storage of roller guides. The total number of roller guide
racks is 20.

ROLLS RACK:
The roll racks are used for keeping rolls. The total number of rolls racks is
150, with each rack holding 9 rolls.

STORAGE RACK 1:
In these racks Heavy guides (static guides) will be stored. The total number of
storage racks for heavy guides is 40.

STORAGE RACK 2:
In these racks, bearing and associated spares will be stored. The total number
of storage racks for this purpose is 15.

50
 CHAPTER 6

MAINTENANCE OF STAND MILLS AND SHEARS

6.1 Cartridge stand ejection/insertion unit:

It is designed to pull out the roll unit toward the changing table and push back it,
when the cartridge stand change takes place. The cartridge stand ejection/insertion
unit comprises: A trolley holding the cartridge stand during the changing
operation.

Oil lubrication system of the reduction pinion stand:

The oil lubrication of gears and bearings is forced by means of an independent
oil lubrication central unit type CLC.
Through the delivery piping's, the oil reaches the parts to be lubricated:
• The tooth face of gears is sprayed by means of spray nozzles;

• The bearings receive the oil from feeding pipes.

The oil flows to the collecting sumps placed in correspondence to the bearings
simply by falling down, the oil is discharged to the bottom through the draining
holes made on the machine body.

At the entry side, the delivery piping is equipped with a filter for impurities, a
flow indicator, and a manometer. On the pinion body is mounted a breather
filter.
The oil collected on the bottom is sent again to the central unit through return
piping.

Air/oil lubrication system:

The system is provided for the intermittent lubrication by means of a mixture
of oil and air of the Roller Guide at preset cycles: The oil flow is provided by
the CLN air-oil lubrication central unit. The air is drawn, filtered and
lubricated from the general constant distribution network.

Grease lubrication system:

The following components are grease lubricated with a centralized
system: Axial thrust bearings, radial bearings and labyrinth flanges
51
mounted on the rolling cylinders;
Roller bearings of the spindle support unit.

Grease lubrication:
Slides, screw down system, gear coupling, cardan spindle and other points are
lubricated manually through grease nipples.

6.2 Hydraulic system:

All the hydraulic devices are fed by the hydraulic central unit type CLO
through a valve bench. The interlocked devices are:
• Hydraulic motor for rolling rolls gap adjusting:
• the distribution manifolds equipped with nozzles

Water cooling system: It is made of rigid pipes and hoses. It is used for
feeding the distribution manifolds equipped with nozzles for cooling the
rolling rolls and for the heat exchanger of the motor.

6.3 SET-UP AND PRODUCTION CHANGE:

The machine set-up for a production cycle involves a series of checks and
operations in order to guarantee the machine operating safeness and its
complete adherence to the requested rolling schedule.
The setting of the machine includes the following operations:
• Change and alignment of the rolling groove with rolling axis;
• Regulation of rolling rolls center distance and control of the gap between
the rolling rolls;
• Installation of the guide equipment at entry and exit
of the cartridge roll stand and alignment with
rolling axis;
• Positioning of the cooling water manifolds in correspondence of rolling
groove.
• On the main control desk pre-set according to the foreseen production the
following data:
• Rolling rolls rotation speed.

52
6.4 CHANGE OF THE ROLLING GROOVE:
At machine stopped, proceed as follow:
• Close the on-off valve of the cooling water feeding net;
• On the local operating station, select switch from "remote" to "local";
• Switch motor off from the control desk and secure the drive according
safety procedures.
• Remove the entry and exit guide equipment (when it prevents the
movement);
• Remove the water manifolds in case the new groove requires a new type of
cooling;
• Operate the unlocking of the hydraulic clamps locking the stand to the
vertical basement unit;
• Start the hydraulic motor of the screw jack’s unit to move the cartridge
stand;
• Accurately check the alignment with the rolling axis using a collimator;
• When the correct position is reached lock the stand by the hydraulic clamps
• Check the gap between the rolling rolls according to the section which is
rolled (see "Roll pass design");
• Carry out an orthogonal check of the half groove using the collimator or the
template (see also the relevant paragraph);
• Place the cooling water manifolds in line with the rolling groove. Make sure
that the manifold is suitable to the type of groove;
• Reinstall the guide equipment on the rest bar, shift and align it with the new
channel using a ruler or a collimator (see the chapter "Alignment of guide
equipment").
• Note: To handling the equipment use the proper lifting tools.
• Carry out a check of the guide equipment alignment using a collimator for
an accurate operation; then fix the guide equipment by the clamp screws;
• Align all the devices positioned either at inlet or outlet referred to the
equipment (raceways, pipes, lopper and so on
• Install all the safety devices foreseen;
• Return on "local" station switch back to "remote";
• Activate the main motor drive;
• Activate the cooling water system.

53
6.5 ADJUSTMENT OF THE ROLL GAP BETWEEN THE ROLLING
ROLLS:

Function of the rolling cycle (see "Roll pass design") it is necessary to proceed
to the adjusting of the gap between the rolling rolls.
Note: Normally the adjustment of the trim of the four chocks of the rolling
rolls is carried out in workshop.
Check the trim of the four chocks inserting some shims between the rolls.
• If the rolling rolls are aligned and parallel, the gap between the rolling rolls
(work center distance) is gauged by the hydraulic motor with the coupling
connected.
• If the rolling rolls are not parallel, it is necessary to execute the independent
regulation of the chocks:

o releases the coupling; o aligns the chocks

acting the shaft by a proper wrench; o when the
alignment is made connect the coupling; o
proceeds to the gap adjusting

6.6 START-UP USE AND STOPS:

This chapter describes the operations to be carried out when starting the
machine, in order to correct any bad running and for short or long plant
shutdowns.

OPERATIONS REQUIRED BEFORE START-UP:

• Before checking the machine make sure that the hydraulic system central
unit, the oil lubrication central unit, the air/oil lubrication central unit
(consult the specific manuals) and the water system are functioning
correctly.
• The following are the main checks to carry out before each start-up.
• Check the condition and the level of wear of the groove planned for the
rolling operation.
• Make sure that all the guide equipment has been cleaned and check their
condition.
54
 • Check the alignment of the guide equipment with respect to the rolling axis.
• Check the proper position of the cooling water header and of the spray
nozzles on the rolling groove.
• Make sure the safety devices required by accident prevention rules have
been installed on the machine.
• Check the efficiency of the control devices.
• Using the relative controls on the main control desk, check the presence of
the alarm signals; if necessary, reset any signal present.
• Note: It is a good rule to check the alarms devices, installed on the machine,
to check the incorrect operation.
• Check the proper operation of the oil lubrication system:
o the oil flow rate at machine entry on the flow
indicator; o the oil pressure on pressure gauge.
• Note: If necessary, set up the control devices in order to obtain the correct
pressure and flow values.

• Check the correct operation of the hydraulic system (operating pressure)

and the functioning of the interlocked devices from the local desk.
• Check the proper operation of the water-cooling system. o with the valves
completely open, check the correct working pressure and flow of cooling
water.
o Check that the sprayers are clean and correctly positioned: check the
evenness and width of the spray cone and/or spray blade.
• Check the proper operation of the air-oil lubrication system (operating
pressure and lubrication cycle).
• Check that there are no leaks from the connections on the systems (oil,
water, air/oil, and so on);
• Check the correct setting of the machine according to the rolling schedule:
check if
the speed cascade adjustment of the electrical motor is activated and if the
rolling speed is as prescribed.

OPERATION TO BE CARRIED DURING FUNCTIONING:

• During operation, check the proper functioning of the machine; therefore,
carry out the following checks.
55
• Check that the rolled material does not produce anomalous loops and that
it is not in tension: check the cascade rolling speed and the current
absorption of the motor.
• Check the regular operation of the cooling headers for the rolling groove.
• Check the correct operation of air-oil lubrication system:
o Check that the signaling pistons on the distributor move during the
lubrication cycle, going through at least one upward and downward travel.
At the completion of the cycle, the piston must be in the "fully lowered"
position, as an intermediate position indicates a faulty operation of the
system (it remains possible to carry out the cycle in the manual mode from
the local control panel);
• Moreover, check the proper functioning and efficiency of:
o reduction pinion stand oil lubrication
system; o rolls cooling system; o
hydraulic system.
• Check that there are no leaks in the fittings and pipes.
• Check for noises or vibrations which can indicate the necessity to carry out
preventive maintenance.
• Eventual troubles in the operation of the machine are instantaneously
indicated on the signaling panel provided for the purpose by means of
acoustic and visual signalization. The acoustic alarm can be switched off
through a push-button; the visual signalization remains ON until the
problem has been corrected and the reset push-button has been pressed.
• Four types of alarm signals are normally foreseen (refer to "Electrical
sequences" manual separately supplied):
• Alarm type 0: It only produce a visual signalization.
• Alarm type 1: It only produces an acoustical and visual signalization
• Alarm type 2: It produces an acoustical and visual signalization and stops
the associated machine or drive at the end of the cycle in progress.
• Alarm type 3: It produces an acoustical and visual signalization and stops
immediately the related machine or drive.

56
TROUBLESHOOTING:

PROBLEM CAUSE REMEDY

Loose anchoring bolts Tighten screws and bolts
between basement and
foundations and between
the different machine
components.
Belleville springs pressure Replace them
drop.
Incorrect alignment of Align the transmission
transmission couplings shafts and lubricate the gear
Noise coupling
Fastening and alignment of Align the transmission unit
the cardan shafts and lubricate the journal
crosses and the splined
section
Insufficient lubrication of Lubricate properly
the transmission couplings
(gear couplings, cardan
shafts)
Condition of the bearings Check the lubrication

Check the bearings slacks

Check the alignment of

parts

Check the balancing of the

rotating parts
Condition of the Gears Check the lubrication

Check the teeth clearance

57
 Check the balancing of the
rotating parts

Presence of air in the Discharge the air from the

springs circuit completely. Clean
the breather filter.

Fastening of guide Tighten firmly the locking

equipment screws

Check the lubrication

Condition of the bearings Check the bearings slacks

Condition of the gears Check the lubrication

Check the teeth clearance

Overheating
Inadequate cooling water Clean the sprayers and
system eliminate the calcareous
scale inside the tubes and
manifolds. Filter the water

Missing of lubrication Check the correct

functioning of the air or oil
Excessive temperature in lubrication
the rolling rolls bearings
Check the feeder’s capacity
and verify the integrity of
the feeding pipes
Power failure Check the electrical system

58
 Stoppage of drive motor Check the motor and
electrical
system

Broken shear pins on safety Re-install the safety pins

Machine stop couplings on the coupling see
manufacture’s
instructions

No oil circulation in the Check the oil lubrication

reduction gears system see CLC manual
instructions

Filter clogged Remove and clean the filter

Rollings rolls cooling Check the water-cooling

Breakdown of rolling rolls inadequate or not effected system
(Thermal shocks) and the delivery

Clean the sprayers and

eliminate the calcareous
scale
inside the tubes and
manifolds

Filter the water

Cool the water

The bar stops between the Check the efficiency of the

rolling rolls cause of a emergency systems
stranding

59
 Improper use of the torch Do not use the torch near
during a stranding (thermal the
shocks) rolling rolls

Rolling defects Groove worn out or Replace the rolling groove

damage

Alignment of the groove Carrying out the alignment

with respect to the rolling again
axis

Improper alignment of the Carrying out the alignment

groove between rolling again
rolls

Wrong alignment of guide Carrying out the alignment

equipment with rolling again
axis

Insufficient gap between Increase the gap (center

the distance) between the
rolling rolls rolling rolls according to
the rolling schedule see the
rolling cards
Wrong rolled section speed Reconsider the rolling
program and the relative
speed variations. Carryout
the necessary adjustments

60
6.7 PREVENTIVE MAINTAINANCE :
Preventive maintenance includes all those checks and operations necessary to ensure the
plant most operating efficiency and to prevent damages or failures.
• The above-mentioned operations, based on experience and/or theoretical
calculations, consist in periodical interventions to prevent failures and in
thorough inspections to check the conditions of a machine component.
The inspections are mainly based on operative personnel observations and
include:
• Visual observation: for fluid leaks and blow-by, vibrations, cracks, wear,
etc.
• Noise listening: for creaking, hissing, unusual noise, vibrations, etc.
• Sensorial detection: for temperature, vibrations, unusual roughness, etc.

• Such checks and interventions must be carried out within the pre-arranged
terms, as indicated in the manual for preventive operations. These intervals
may vary according to working conditions.
• The operators should report the detected data and their comments upon the
integrity and efficiency of the item in a special register, in order to choose
the operation to be carried out before trouble develops.
• Increased inspections by means of special tools or based on the operative
personnel's observations, make it possible to decide whether the operation
should be carried out immediately or postponed until the first programmed
stop of the working cycle.

PREVENTIVE MAINTENANCE SCHEDULE:

Here below there is a list of the main preventive maintenance operations to be

scheduled for the perfect machine preservation.

1. Cleaning and checks:

Remove any dirt and dust from the machine by means of a special industrial
vacuum cleaner. If there are grease or oil spots, wash with oil-solvents (for
instance, petroleum solvents like gas oil). Regular cleaning of mill stands
to remove dust, debris, and other contaminants that may affect
performance.

61
2. Fastening elements:
Check the tightening of nuts and bolts, in particular the foundation tie
rods, tighten always with the required torque. Regular inspection and
tightening of bolts and fasteners to prevent loosening during operation.

3. Gear coupling:

a) Check the gear coupling noise.

If unusual noise is found, make sure that there are no excessive backlashes or
other damages.

b) Check the correct sliding of the gear coupling flanged sleeves; in case of
seizing, carry out a maintenance intervention to check the component
integrity.

c) Check the alignment of the shafts connected by the gear coupling. Note: For
further information, see the manufacturer's documentation.

d) Check the correct tightening of nuts and screws, by means of a

dynamometric wrench and proceeding in crossed manner.

e) Look for any lubricant grease leakage. Leakages on the seal rings indicate
an excessive maladjustment between the shafts. In this case, it is necessary
to disassemble the coupling and carry out a new alignment of the shafts.
Moreover, take the opportunity to check the components as well as the
efficiency of the seal rings which, if necessary, will have to be replaced.

f)Check the setting and integrity of the shear pins on the safety coupling. See
also Manufacturer's instruction.
The safety pins are stressed components and must be replaced at the
following interval: every 4800 working hours

g) Grease the gear coupling according to the instructions of the "lubrication

table" (see the "Lubrication Tables Collection - LTC" manual). There are
three ways to re-grease the gear coupling:

62
h) Check the correct tightening of nuts and screws, by means of a
dynamometric wrench and proceeding in crossed manner.

i)Look for any lubricant grease leakage. Leakages on the seal rings indicate
an excessive maladjustment between the shafts. In this case, it is necessary
to disassemble the coupling and carry out a new alignment of the shafts.
Moreover, take the opportunity to check the components as well as the
efficiency of the seal rings which, if necessary, will have to be replaced.

j)Check the setting and integrity of the shear pins on the safety coupling. See
also Manufacturer's instruction.
The safety pins are stressed components and must be replaced at the
following interval: every 4800 working hours

k) Grease the gear coupling according to the instructions of the "lubrication

table" (see the "Lubrication Tables Collection - LTC" manual). There are
three ways to re-grease the gear coupling:

• Gear coupling re-greasing.

Two grease nipples are assembled on each half coupling, staggered
180°one with respect to the other. Carry out the following operations: o
carefully removes any old grease from the two half couplings; o position
the coupling so that one of the two grease nipples is turned upwards;
o remove the top grease nipple to allow any air blow-off; o
connect the grease pump to the bottom grease nipple and
pump the correct grease quantity;
o remove the pump and install the grease nipple previously
removed; o removes any grease in excess.

• Grease change without disassembling the gear coupling.

o Remove the protection guard from the gear coupling.
o Remove the grease nipples.
o Discharge the old grease through the grease nipple hole, by
means of a jet of compressed air.

63
 o Fill the coupling for more or less 2/3 of its capacity with a
very liquid detergent fluid.
o Re-assemble the grease nipples and turn the coupling
leadless for about15 minutes or until the grease mixed with
the fluid becomes liquid enough to be discharged through
the grease nipple hole.
o If necessary, repeat this operation until the old grease is
completely eliminated. -Position the coupling so that the
grease nipple is turned upwards and remove it to allow the
air blow-off.
o Connect the grease pump to the bottom grease nipple and
pump the correct grease quantity.
o Remove the pump and install the grease nipple previously
removed. o Remove any grease in excess.
At the end of this procedure, install the safety guard.

4. Check the Carden shaft:

a) Check the Cardan shaft for noise. If noises develop in the transmission
joints under operation, check for excessive clearances or other damages.
b) Check the Cardan shaft for slack. The check must be carried out before
lubricating both the journal crosses and the splined section. When there is
an excessive slack, it is necessary to repair the joint.
c) Check, using a dynamometric wrench and proceeding in and screws crossed
manner, the correct tightening of nuts at which fasten the shafts and the
sleeve and the sleeve connecting flanges.
d) Grease lubricates the cardan shafts according to the intervals and with the
lubricant
shown in the lubrication table (see the "Lubrication Tables Collection -LTC"
manual).

Relubrication of cardan shafts

Note: For further information, see relevant chapter "Cardan spindle general
over hauling" of the "Extraordinary maintenance".

64
 To relubricate, the cardan shaft must be at the minimum travel. The grease
nipples must not be removed or replaced.
Pump the grease in an even manner (without spurts), avoiding an excessive
pressure (15 bar max).

Journal cross
Each journal cross is fitted with a grease
nipple: o cleans the grease nipple;
o connect the grease gun to the nipple and pump in grease until grease
comes out of the seal forming a compact layer as a collar;
o remove the gun and remove any excess grease.

Splined section
A grease nipple is fitted on the sleeve:
o cleans the grease nipple; o connects the grease gun to the nipple and
pump the correct quantity of grease; o removes the gun and remove
any excess grease.

5. Component to be lubricated:
Lubricate with grease all the components that need it according to the intervals.
Regular lubrication of bearings, gears, and other moving parts to reduce friction
and wear.

6. Oil lubrication system:

a) Make sure that oil is entering the reduction pinion stand at the proper flow
rate.
b) Check the condition of the oil strainer installed on the inlet pipe unit. For
cleaning proceed as following:
o remove the cap; o removes the
filtering element;
o wash everything (cap, tank) with a
detergent oil; o dry everything using
compressed air;

65
 o introduce
the new filtering element; o
reassembles the filter and the cap as
before.

c) Check the circuit of the oil system.

Check the sealing of the pipes and unions.
If there are leakages in the unions, replace the gasket and tighten completely
the union. If this is not enough, replace the union.
Make sure that there are no oil leakages from the fastening flanges. Any
defect which might be found, must be immediately eliminated.

7. Reduction pinion stand:

a) Look through the inspection hole and make sure that all
the oil nozzles are operating properly. Also make sure that
the pipes which feed oil to the bearings are not obstructed
or damaged. If necessary, clean all the oil paths and ducts.

b) Check the condition of the oil at breather filters. For

cleaning and replacement proceed as following:
o remove the upper cap;
o remove and change the filtering element;
o absorb the exhaust oil from the tank below using a rag or a syringe; o
wash everything (cover, tank) with a detergent (gasoline); o dry
everything using compressed air;
o refill with pure oil (same type as for the machine) the tank up to the
level signed with a notch on the outside of the basin;
o reassemble the exhaust filter as before.

c) Make sure that there are not oil leakages from fastening flanges and the
gaskets of the shafts.

d) Check gear noise.

o If unusual noise is heard, it may be due to insufficient lubrication or to
excessive wear in the gears.
66
 o For an accurate check it is advisable to use the appropriate device (for
example an electronic stethoscope).
o If necessary, stop and lock the machine drives, and then carry out a
visual inspection of the teeth to make sure they are not damaged. Note:
See also the following paragraph.

e) During functioning, constantly check the bearings noise. For an accurate

check of
bearings it is advisable to use the appropriate device (for example an
electronic stethoscope).

f) Check the bearing temperature, which must never exceed 70°C on the outer
blocks.
o This check can be carried out with the machine running or
immediately after the machine stop, using the adequate instrument
(for example a digital thermometer).

g) During the shutdown of the machine, if necessary, the following checks can
be carried out:
o proper position of the bearing's inside and outside rings;
o cleanliness of the bearing;
o condition of the casings containing the rotating components; o onset of
signs of damage on bearing races (by rotating the shafts slowly); o axial
play of the shafts (using a comparator);
o axial play of cylindrical or barrel roller bearings (to check with a
centesimal thickness gauge).
Check the bolt tightening and the alignment of the connected machines.

8.Rolling rolls water cooling system:

a) Check the proper operation of the water-cooling system and make sure that:
o the water flow rate and pressure are correct; o the water supply is
constant to ensure a regular cooling of the rolling rolls.
b) Check the efficiency of the cooling water ramp and make sure that the
spray nozzles are clean, otherwise clean them. Carry out this check at the
67
 following interval (Every 800+1000 operating hours) With the same
frequency, also check wear and cleanliness of the sprayers (wherever
present) on the guide equipment at the rolling stand. Note: Whenever the
water pipes are removed, clean them in order to remove any lime deposit.
c) Check the condition of the hoses and, if damaged, replace them. If there
are leakages in the unions, replace the gasket and tighten completely the
union. If this is not enough, replace the hose.
d) Check the water system circuit.
Check the sealing of piping and unions.
Carry out a visual check of the component integrity.
Any defect which might be found, must be immediately eliminated.

2 Air/Oil lubrication system:

a)Check the proper operation of the oil meters on the double-line system by
checking the movement of the rods, which can be seen inside the turret.
Using a pressure gauge, check the oil and air working pressure; if necessary,
make the necessary adjustments

b) Check the circuit of the oil system.

o Check the sealing of the pipes and unions;
If there are leakages in the unions, replace the gasket and tighten
completely the union. If this is not enough, replace the union.
o Carry out a visual check of the component integrity. If the hose is
damaged, replace it.
o Make sure that there are no oil leakages from the fastening flanges.
Any defect, which might be found, must be immediately eliminated.

c) Check the air system circuit.

o Check the sealing of piping and unions.
If there are leakages in the unions, replace the gasket and tighten
completely the union. If this is not enough, replace the union. o Carry out
a visual check of the component integrity. If the hose is damaged, replace
it. Any defect, which might be found, must be immediately eliminated.

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3 Rolling rolls:

Check the condition of the grooves. Check for signs of unusual wear on the
entire rolling groove circumference. This problem could be caused by a
defective water feeding system or by clogged spray nozzles. The persistence
ofthe problem can cause visible cracks all around the rim which could cause the
rolling roll to break within a short time. Rolling grooves with cracks which are
visible to the naked eye should not be used. The cracking or flaking of a
finishing groove roll can also be noticed on the finished product, which will
show small scales or metal projections at constant distances. It is a
recommended practice to check all the rolling grooves whenever, there is a
pause in production.

4 Rolling rolls bearings:

d) During functioning, constantly check the bearings noise. For an accurate

check of bearings, it
i s advisable to use the appropriate device (for example an electronic
stethoscope).

e) Check the bearing temperature, which must never exceed 70°C on the outer
blocks.
This check can be carried out with the machine running or immediately after
the machine stop, using the adequate instrument (for example a digital
thermometer). In case of anomalies, these must be carefully examined for
deciding what type of intervention must be done and if immediate or
programmed in future.
In workshop, every time the rolling rolls are changed, make the following
checks:
o proper positioning of the bearing inside and outside rings; o cleanliness
of the bearing; o condition of the revolving parts boxes;
o set of signs of damage on bearing races (by rotating the shafts slowly);
axial play of the shafts (using a comparator);
o axial play of cylindrical and barrel roller bearings (to check with a
centesimal thickness gauge).
69
 All these simple checks of bearings contribute to improving operating safety
and do not reduce the machine availability.

5 Centre distance adjusting control unit:

Check the center distance adjusting control unit: as follows:

• remove the cover, thoroughly check the internal parts, and eliminate
possible damages due to water leaking or condensation.
• grease all the moving parts inside and reassemble the units
• make sure all the tightness is reassembled using serviceable and stable
plastic seal.

Rolling Rolls

70
 Rolling Rolls Bearing
13. Carden shaft for axial adjustment:

Check the cardan shaft installed on the top rolling roll adjustment unit as follows:
• Remove the cardan shaft from the machine.
• Check the conditions of the rubber bellows installed on the cardan joints
and the one on the splined shaft. If they are ruined change them.
• Check sliding of the splined shaft and in case its difficult proceed to its
lubrication using the grease nipple. In case of even small damages on the
protections like cuts and cracks it is necessary to change them. Take this
opportunity for cleaning all the components and before assembling
lubricate as follows using a soft spatula (the quantity and type of grease is
indicated in the lubrication table);
71
 • For the joint bend it until the ball and pins appears and proceed;
• For the splined shaft proceed with bellow on and in all open position. Then
assemble the bellows on the joints and tighten the hose clamps.
Note: For further information, refer to the manufacturer's documentation.

14. Guide equipment: Check the condition of the guide equipment for the rolled
stock. Also check this equipment for excessive wear of guide rollers. Whenever the
life of roll pass is over, then changing of roll pass is done by adjusting the guide.

15. Fast connecting plates:

To extend the life of the gasket, apply a very thin layer of air oil with a brush or a
putty knife on the following parts of the fast connect plate:
• sides of mating surface of the plugs;
• sides of mating surface of the electric connector male;
• guide post.

Card and Shaft

16. Welds: Check the welded joints in order to find out possible cracks. If necessary,
make a new weld, and keep into account the possible thermal expansion and
shrinkage. Weld the hub when it is worn out.

17. Calibration: Calibration of sensors and measuring instrument to maintain

accuracy in measurement

18. Alignment: Periodic alignment checks to ensure proper positioning and

alignment of mill stands.

72
 CHAPTER:7

CRANES
7.1 EOT Cranes:
Electric power for operation of the cranes is made available at 415 V, 3-phase, 4
wire, 50 Hz, 4th wire being earthed conductor.

The following types of cranes are installed throughout the mill at different
locations, designed to meet specific requirements. A brief explanation of these
is mentioned below:

Furnace Aisle EOT

Crane: Main hook: 15
T Auxiliary hook: 7.5T
Quantity: 1
Purpose and location: For maintenance of furnace in Furnace Aisle (A-B
bay)
 Mill Aisle 50/20T EOT Crane (MAGNET ON AH):
Main hook: 50 T
Auxiliary hook: 20 T
(Magnet) Quantity: 1
Additional remote control
Purpose and location: For handling mill strand, rolls and miscellaneous
work in Mill Aisle (B-C bay)

Mill Aisle 20/5T EOT Crane:

Main hook: 20 T
Auxiliary hook: 5
T Quantity: 1
Additional remote control
Purpose and location: For maintenance of equipment and other miscellaneous
work in Mill Aisle (B-C bay).

Roll Shop 50/20T EOT Crane:

Main hook: 50T
Auxiliary Hook:20T
Quantity: 1
Add. Remote Control
Purpose and location: For handling rolls assembly, rolls in Roll Shop (C-D bay).

74
Collecting And Dispatch Area EOT Crane:
Lifting Capacity: 20 T
Quantity: 6
All cranes are magnet equipped
Two out of the six cranes have an auxiliary hook of 5 T capacity
Purpose and location: Collecting, stacking and dispatch of finished product
packets/bundles from A-B and C-D bays, with three cranes in each. The auxiliary
hook is used chiefly for mounting straps on strapping machine.

7.2 Semi Portal Cranes:

Capacity: 5 T
Quantity: 2
Purpose and Location: Guide Assembly area, Stand Preparation area work
in roll shop

7.3 Jib Cranes:

Jib cranes are installed at various places in the mill for the following
functions:
• Changing blade disc of cold saws
• Changing blade disc of sample saws
• Works in Saw blades sharpening area
• Handling guides and bearings in roll shop

76
 CONCLUSION

In conclusion of this report, it represents the detailed study and significance of all
departments and comprehensive analysis of a rolling mill of RINL-VSP. A steel
plant uses the raw materials like Coal, Dolomite, Limestone, Iron Ore, which
produces byproducts and are used entirely to transform pig iron into steel. The
above report describes the importance of rolling mills in a steel industry and also
the vital components of the manufacturing processes and maintenance involved
in it. This study explains about the various functions, operations, challenges,
advantages of a rolling mill. Structural mill is a rolling mill where hot metal is
passed through a series of rollers making the material to elongate by means of
comprehensive force which ultimately increases the mechanical properties of the
product. A rolling mill can produce a wide range of steel products in different
shapes and sizes as per the requirement of market. Maintenance of rolling mills
require significant financial resources and precise methods to ensure the efficient
and safe operation thereby increasing the production and lifespan of the
machinery. By implementing appropriate methods like preventive and predictive
maintenance which includes frequent inspection, lubrication, planned shutdowns,
required repairs such that rolling mills can ensure the increase in lifespan of
machinery, production and can also prevent the accidents or injuries. Thereby
from this report we understand how to maintain mill stands and shears to increase
the productivity of a rolling mill making it the competitive edge of a steel
industry.

Thank you

78