1Bangladesh Steel Re-Rolling Mill(BSRM)

HASAN SHAHRIAR SAJIB

Studying B.Sc. Engineering

Mechanical Engineering

Bangladesh University of Engineering & Technology (BUET)

2STEEL SECTOR IN BANGLADESH

Bangladesh has more than 400 steel mills Total production capacity 80 lakh tons Country demand 40 lakh tons Steel consumption 25 kg/capita Leading steel companies: BSRM, KSRM, AKS, RSRM, GPH, PHP etc. BSRM and AKS provide 50% of country demand

3INDUSTRY OVERVIEW: BSRM

First fully automated Re-rolling mill in Bangladesh Operated since 1952 Was sister concern of Meghna Engineering Works Ltd BSRM Steels Ltd. Started operation since April 1,2008 Initial production 3.75 lakh tons per year At present production is about 7 lakh tons per year Industry was fully conceptualized by Forni Industriali Bendotti (Italy) and

Denieli group (Belgium)

4INDUSTRY OVERVIEW: BSRM Main product in Xtreme 500w, also produces 400w, 300w, 200w, 60 grade, 40 grade

1984 Introduced high strength cold-twisted steel bars to the construction industry.

1987 Introduced ASTM 615 grade 60 reinforced steel bars.

1996 Commissioned the largest billet making plant in the country.

2006 Introduced micro reinforcement wires for low cost rural construction.

2008 Introduced grade 500 steel bars, the current international standard for modern construction-BSRM Xtreme 500 W.

2008 BSRM group contributed nearly tk.100 crores to the national exchequer in taxes, levies, duties and vat.

2009 The largest billet making plant of the country nears completion

5THE ADMINISTRATIVE INFRASTRUCTURE OFBSRM STEELS LIMITED

The entire work schedule of the industry is divided into 11 departments. They are:

Accounts Admin HR and IR (Human Resources and

Industrial Relationship) Inventory CSD (Customer Service and

Development) Production Department

workshop Electrical Mechanical QA (Quality Assurance) and T&D (Technical and Development

6ORGANOGRAM

7WATER TREATMENT PLANT (WTP)

WTP supplies required water in the mill, and treats the used water for re-circulation

Two types of water used- • Contact (used in mill)• Non-contact water ( used in QTB and heat exchanger)

Total pumps: 31 Total filter: 5

• 3 sand filters (used for filtering Contact water) • 2 anthracite filters (used foe removing iron particles)

8WTP OVERVIEW

9WATER TREATMENT PLANT (WTP) Water filtration process: 3

• Manual• Chemical• Filtering

Backwash method is done in every 8 hours for removing scale from filter Chemical used : NaOCl, anti corrosive chemical, coagulants, dispersants etc. Cooling tower:

• total 7, forced induced drafts• Reduces temperature almost 8 degree Celsius• Total capacity : 3000 m3/hr.

10FURNACE Furnace type:

Pusher Billet type Re-heating Furnace Dimension:

• Length: 22m• Width - 15m • Height - 7m

Burner number: Total 22 • 10 in heating zone, 12 in soaking zone

Air-Fuel ratio: 10:1Fuel used:

Duel fuel:• Natural Gas• Light Diesel Oil (LDO)

Pressure: 0.3 bar Temperature: 1200 degree Celsius

11FURNACE

3 zones:• Pre-heating zone (billets are heated by pre-heated air up to 400˚ C)• Heating zone (billets are further heated up to 1200˚ C)• Soaking zone ( maintains the temperature gained in heating zone)

Peel bar :

Used to push the billet out of furnace Billet detector ;

2 billet detectors are used for positioning the billets inside the furnace Recuperator:

Used to pre heat air

12MILL AREA

Heated billet goes through a shape changing process by rolling Two types of rolling stand:

• Vertical: 8• Horizontal: 12

Three area:• Roughing area: 8 stands• Intermittent area: 6 stands• Finishing area: 6 stands

Looper: max. 6 (use to reduce tension of heated rod) Slitter: use to split the billet for less dia. rod

13MILL AREAQTB (Quenching and Tempering Bath)

Use for uniform cooling of heated rod Martensite formation Direct contact of water, rapid cooling Temperature is reduced by 200 C ̊ ̊

Shear Machine: Detach the billet in head & tail position Three shear machine

• Shear 1 (between stand 6&7, cuts the head portion)• Shear 2 (between stand 12&13, cuts the tail portion)• Shear 3 (placed after QTB, cuts the billets according the cooling bed size)

14FINISHING AREA The quenched rod after shear-3 moves through here The main components operating in Finishing Area are:

• Inclined Apron Roller Table • Cooling Bed• Cold Shear• Tying Machine

Inclined Apron Roller Table • 72 motor-driven rollers: imparts motion to the discontinuous rods• 71 Lifting Aprons: shifts the rods lengthwise to the cooling bed• 5 interconnected hydraulic cylinders: controlling simultaneous opening and closing of the

aprons• 3 Magnetic Stoppers: stops the rods moving at high velocity

15FINISHING AREA Cooling Bed

Two types of racks; Fixed and Movable: shifts the rods along transverse direction

These Movable jaws are driven by a single motor.

Two gear boxes having worm gear transmits power from motor.

Eccentric cylindrical cams are connected in series in the driven shafts.

Cams have counterweight adjusted at 180 degree.

Hydraulically driven arms transfer the rods from the cooling bed to a rolling trolley

The rolling trolley transfers them in their longitudinal direction to Cold Shear Cold Shear

AC Motor Driven System

Motor Flywheel Clutch-Brake System

Axially displaced parallel shafts by cams to move the upper jaw to cut the rods.

Belt pulley

16FINISHING AREA Layer Chain Transfer Vertical Chain Transfer Tying Machine Tying Machine:

• 5.5mm wire is spool fed• Hydraulic Mechanism with Hydraulic Motor ,oil storage tank for hydraulically

driven small rollers or flap.• 8 steps controlled either automatically or manually

1. Feed wire- by hydraulic motor.

2. Clamp wire- by hydraulic cylinder.

3. Binding unit up- by hydraulic cylinder.

4. Stretch wire- by reversing hydraulic motor.

5. Twist knot- by hydraulic motor.

6. Wire clamping off- by hydraulic cylinder.

7. Reset twisting head- by hydraulic motor.

8. Binding unit down- by hydraulic cylinder.

17OVERHEAD CRANE 4 Bays 12 Overhead Cranes Magnetic Type A-B Bay :

• 3 cranes• Girder Capacity: 29 tons• Lifting Capacity: 8 tons

B-C Bay:• 4 cranes• Girder Capacity: 24 tons• Lifting Capacity: 8 tons

C-D Bay:• 3 cranes• two of 10 tons, one of 20 tons

D-E Bay:• 2 cranes• 10 tons and 20 tons

18OVERHEAD CRANE Types of Motions:

1. Long Travel

2. CROSS travel

3. Hoisting Travel (Lifting and lowering)

4. Rotational Travel

5. Telescopic motion (A-B Bay only) Lifting Mechanism:

1. Magnetic action induced by Electric flux change

2. Battery backup for 20 minutes to the magnets

3. Hoisting travel control: cable-rope system with brake pads

19UTILITIES Supports the entire mill to run smoothly. Consists of :

• Hydraulic drive system• Pneumatic drive system• Lubrication system• Greasing system

Hydraulic Drive System 4 central hydraulic unit

Furnace central hydraulic unit• Used in driving pusher & peel bar.

Milling central hydraulic unit• Used in driving pinch roll, chain transfer system, hood(up-down movement)

Finishing area central hydraulic unit• Used in movement of QTB, apron lifting operation, tying machine.

Workshop central hydraulic unit• Assembly operation of Robot, band saw up-down.

20UTILITIES

Hydraulic system contains• Tank• Hydraulic oil( vg46 or vg68)• Energy Converters• Control Devices• Accessories (Float valve, Accumulator etc.)• Connecting device• Electrical & Electronic components

21UTILITIES Pneumatic drive system

Application:• Peel bar upper pinch roll• Peel bar entry door• Furnace exit upper pinch roll• Billet Detector• Looper roller up-down

Pneumatic system contains• Compressor• Drier• Receiver• FRL( Filter-Pressure Regulator-Lubricator)• Control Valves• Actuators

22UTILITIES Lubrication

Force lubrication is used in this industry Has 3 units

• Roughing Stand Lubrication Unit• Intermediate Mill Lubrication Unit• Finishing Stand Lubrication Unit

Lubrication system containsReservoirPumpHeat Exchanger( Remove moisture content)Filter( Remove metal & dirt particles)Lubrication oil(vg 220)

23UTILITIES

Greasing system Grease generally consists of a soap emulsified with vegetable oil. A central grease unit is present to pump grease into required places keeping

the time gap to 30 minutes. Has 3 greasing units

• Rolling Mill Central greasing unit• Finishing Area greasing unit• Shear 1 greasing unit• Cold shear central greasing unit

24BENDING MACHINE

Bending machine is used to bend 12 m rods into 6 m rods for carrying in trucks Driven by electric motoring 4 rollers to bend the rods smoothly. A rotating jaw bend the rods. A movable arm driven by pneumatic power helps to slide the rods into delivery

chain transfer 9 men are required to work on a Binding machine

• 3 for counting

• 3 for tying

• 3 for delivery

25QUALITY ASSURANCE (QA) Main Purpose is to ensure the product quality. BSRM always try to improve product quality with best techniques of the world. They ensure ISO 9001:2000 One set of rebar is checked in every hour. For 500W

• Yield strength is 500MPa. • Ratio of tensile and ultimate strength is not more than 1.15

Testing Instruments:• Bar bending mandrel• CNC roll turning lathe• Universal testing machine• Computer attached with UTM• Spectrometer • Microscope

26REBAR

Three layers • Martensitic case• Transition zone• Ferrite-Pearlite core

Martensitic case provides hardness of steel. Ferrite-Pearlite core provides ductility of steel. Controlling the amount of water flow of QTB, we can control the marten site

layer thickness. Martensitic layer should not be more than 40% of total rebar x-section area.

27WORKSHOP The workshop of BSRM is very much enriched. The performance of the workshop

machines makes the industry self- dependent. Excelled engineers and technicians maintain the workshop.

The work shop instruments:• Shear Machine• CNC-Roller notching Machine• CNC-Lathe Machine• Manual Lathe Machine• Bench Drill Machine• Radial Drilling Machine• Surface Grinding Machine• Robot

28WORKSHOP FACILITIES

Dressing of gear teeth Surface grinding operation Repairing mechanical equipment Interchanging between horizontal and vertical stands

BSRM does all kind of repairing and maintaining works in their workshop. This saves a large amount of money of the industry and enhances the profit.

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