1 Rolling Definition: Definition: The first process that is used to convert material into a finished wrought product. Thick starting stock rolled into.

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RollingRolling Definition:Definition:

The first process The first process that is used to that is used to convert material convert material into a finished into a finished wrought product. wrought product. Thick starting Thick starting stock rolled into stock rolled into blooms billet or blooms billet or slabsslabs

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Types of RollingTypes of Rolling flat rolling:flat rolling:

The final shape of the The final shape of the product is either classed product is either classed as sheet or plate .as sheet or plate .

Profile rolling:Profile rolling:

The final product may be a The final product may be a round rod or other shaped round rod or other shaped bar, such as a structural bar, such as a structural section (beam, channel, section (beam, channel, joist etc) joist etc)

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Profile RollingProfile Rolling

Definition:Definition:

Rolling is defined Rolling is defined as the reduction as the reduction of the cross-of the cross-sectional area of sectional area of the metal stock, the metal stock, or the general or the general shaping of the shaping of the metal products, metal products, through the use of through the use of the rotating rolls.the rotating rolls.

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Classification of RollingClassification of Rolling

Hot rolling.Hot rolling.

Cold rolling.Cold rolling.

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Hot rollingHot rolling

DefinitionDefinition

Hot rolling is a plastic Hot rolling is a plastic deformation process, deformation process, in which mechanically in which mechanically shapes are fromed of shapes are fromed of the meterial at a the meterial at a temperature above its temperature above its recrystallisation recrystallisation temperature.temperature.

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Benefits of hot rollingBenefits of hot rolling   Flow stresses are low, hence forces and power Flow stresses are low, hence forces and power

requirements are relatively low, and even very requirements are relatively low, and even very large work pieces can be deformed with large work pieces can be deformed with equipment of reasonable size.equipment of reasonable size.

Ductility is high; hence large deformations can Ductility is high; hence large deformations can be taken (in excess of 99% reduction).be taken (in excess of 99% reduction).

Complex part shapes can be generated.Complex part shapes can be generated.

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Disadvantages of hot Disadvantages of hot rolling.rolling.

The hardness is generally lower.The hardness is generally lower.

most metal will experience some most metal will experience some surface oxidation resulting in surface oxidation resulting in material loss and poor final surface material loss and poor final surface finish. finish.

Low producation rate.Low producation rate.

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Cold rolling.Cold rolling. Definition.Definition.

When the rolling When the rolling processing processing temperature of the temperature of the mechanical mechanical deformation of metal deformation of metal is below the is below the recrystallization recrystallization temperature, the temperature, the process is termed as process is termed as cold rolling. cold rolling.

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Advantages of cold Advantages of cold rollingrolling

In the absence of oxidation, tighter In the absence of oxidation, tighter tolerances and better surface finish tolerances and better surface finish obtained.obtained.

Thinner walls are possible.Thinner walls are possible. The final properties of the workpiece The final properties of the workpiece

controlled cold rolling can be retained controlled cold rolling can be retained Wastage is about 6%.Wastage is about 6%. High production rate.High production rate.

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Disadvantages of clod Disadvantages of clod rollingrolling

It has high initial It has high initial cost.cost.

Low production Low production rate.rate.

High power High power consumption.consumption.

High wear and tear High wear and tear of the rollers. of the rollers.

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Flat RollingFlat Rolling

Definition:Definition:

The final shape of The final shape of the product is the product is either classed as either classed as sheet or plate .sheet or plate .

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Rolling MillsRolling Mills Definition:Definition:A A rolling millrolling mill is a is a machinemachine

or or factoryfactory used to shape used to shape and process and process metalmetal by by passing it between a passing it between a pair of working rolls. The pair of working rolls. The metal is passed between metal is passed between two tough two tough cylinderscylinders numerous times, with numerous times, with the distance between the distance between the cylinders being the cylinders being decreased with each decreased with each pass so the metal pass so the metal becomes thinner and becomes thinner and thinner. thinner.

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Type of rolling mills.Type of rolling mills. Cold rolling mills:Cold rolling mills:Cold rolling is a metalworking Cold rolling is a metalworking

process in which metal is process in which metal is deformed by passing it deformed by passing it through rollers at a through rollers at a temperature below its temperature below its recrystallization recrystallization temperature. Cold rolling temperature. Cold rolling increases the yield strength increases the yield strength and hardness of a metal by and hardness of a metal by introducing defects into the introducing defects into the metal's crystal structure.metal's crystal structure.

Hot rolling mills:Hot rolling mills:

Hot rolling is a hot working Hot rolling is a hot working metalworking process where metalworking process where large pieces of metal, such large pieces of metal, such as slabs or billets, are heated as slabs or billets, are heated above their recrystallization above their recrystallization temperature and then temperature and then deformed between rollers to deformed between rollers to form thinner cross sections.form thinner cross sections.

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Classification of rolling Classification of rolling millsmills

Mills classified in accordance with the Mills classified in accordance with the name of the product which they name of the product which they roll, follow: Blooming, cogging and roll, follow: Blooming, cogging and slabbing mills, being the slabbing mills, being the preparatory mills to rolling preparatory mills to rolling finished rails, shapes or plates, finished rails, shapes or plates, respectively. If reversing, they are respectively. If reversing, they are from 34 to 48 inches in diameter, from 34 to 48 inches in diameter, and if three-high, from 28 to and if three-high, from 28 to 42 inches in diameter.42 inches in diameter.

Billet mills, three-high, rolls from Billet mills, three-high, rolls from 24 to 32 inches in diameter, used 24 to 32 inches in diameter, used for the further reduction of for the further reduction of blooms down to 1J^ x IJ^-inch blooms down to 1J^ x IJ^-inch billets, being the preparatory mills billets, being the preparatory mills for the bar and rodfor the bar and rod

Beam mills, three-high, rolls from Beam mills, three-high, rolls from 28 to 36 inches in diameter, for 28 to 36 inches in diameter, for the production of heavy beams the production of heavy beams and channels 12 inches and over.and channels 12 inches and over.

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•Rail mills with rolls from 26 to 40 inches in diameter.•Shape mills with rolls from 20 to 26 inches in diameter, for smaller sizes of beams and channels and other structural shapes.•Merchant bar mills with rolls from 16 to 20 inches in diameter.•Small merchant bar mills with finishing rolls from 8 to 16 inches in diameter, generally arranged with a larger size roughing stand.•Rod and wire mills with finishing rolls from 8 to 12 inches in diameter, always arranged with larger size roughing stands.•Hoop and cotton tie mills, similar to small merchant bar mills11.•Armour plate mills with rolls from 44 to 50 inches in diameter and 140 to 180-inch body.

Plate mills with rolls from 28 to 44 inches in diameter13.•Sheet mills with rolls from 20 to 32 inches in diameter.•Universal mills for the production of square-edged or so-called universal plates and various wide flanged shapes by a system of vertical and horizontal rolls•Tube mills for the production of tubes.•Special mills, such as slitting, piercing, tire wheel mills, etc.•Cold mills.

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Finished product of Finished product of rolling millsrolling mills

First GroupFirst GroupBars, rods, wire rods, bands and Bars, rods, wire rods, bands and

hoops are produced from blooms, hoops are produced from blooms, slabs and billets by reducing this slabs and billets by reducing this material to the simplest forms, material to the simplest forms, such as squares, rounds and flats.such as squares, rounds and flats.

Second GroupSecond GroupShapes are reduced from blooms, Shapes are reduced from blooms,

slabs or billets to forms having slabs or billets to forms having more or less irregular section, the more or less irregular section, the original material is not only original material is not only reduced but it is also developed reduced but it is also developed into a definite shape.into a definite shape.

Third GroupThird GroupPlates and skelp is the material Plates and skelp is the material

obtained by rolling slabs and obtained by rolling slabs and blooms in mills known as plate and blooms in mills known as plate and skelp mills. A sheet is the product skelp mills. A sheet is the product obtained by rolling sheet bars in obtained by rolling sheet bars in sheet mills.sheet mills.

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Shape RollingShape Rolling Definition:Definition:

shape rolling is a shape rolling is a metalworking forming metalworking forming process in which process in which structural shapes are structural shapes are passed through rollers passed through rollers to bend or deform the to bend or deform the work piece to a work piece to a desired shape, while desired shape, while maintaining a maintaining a constant cross-constant cross-section.section.

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ExamplesExamples of shape rolling of shape rolling

I-beams, H-beams, T-I-beams, H-beams, T-beams, Z-beams, beams, Z-beams, angle iron, angle iron, channels, pipes channels, pipes and tubing, bar and tubing, bar stock, and railroad stock, and railroad railsrails

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Process of shape rollingProcess of shape rolling shape rolling uses profile shape rolling uses profile

rolling techniques where rolling techniques where the work piece is passed the work piece is passed through a series of rollers through a series of rollers (of larger magnitude than (of larger magnitude than that of common rolling that of common rolling devices) that match the devices) that match the required geometry, the required geometry, the most common method most common method being the use of 3 rollers. being the use of 3 rollers. When the distance When the distance between the rollers is between the rollers is adjusted, various adjusted, various curvatures can be made.curvatures can be made.

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Seamless TubesSeamless Tubes Definition:Definition:

In this process In this process SeamlessSeamless (SMLS) (SMLS) pipe manufacture. pipe manufacture. is formed by is formed by drawing a solid drawing a solid billet over a billet over a piercing rod to piercing rod to create the hollow create the hollow shell. shell.

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Production Seamless Production Seamless piping and tubingpiping and tubing

The billet is heated to between The billet is heated to between 1200 and 1300°C and then 1200 and 1300°C and then positioned between two positioned between two eccentric rolls arranged at an 6 eccentric rolls arranged at an 6 degree angle to each other and degree angle to each other and operating in the same operating in the same direction, thus locking the billet direction, thus locking the billet into a kind of gear mechanism. into a kind of gear mechanism. As the billet progresses As the billet progresses lengthwise through the rolls in lengthwise through the rolls in a helical motion, it is pierced a helical motion, it is pierced by a plug which is supported at by a plug which is supported at the run-out end of the piercing the run-out end of the piercing mill by a freely rotating bar. In mill by a freely rotating bar. In other words, the plug is other words, the plug is "drilling” the hole into the billet "drilling” the hole into the billet as it passes through it. as it passes through it.

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TubeTube

Definition:Definition:

The pipe which has seam or The pipe which has seam or welded joint in it.welded joint in it.

The weld flash can be The weld flash can be removed from the outside removed from the outside or inside surfaces using a or inside surfaces using a scarfing blade. The weld scarfing blade. The weld zone can also be heat zone can also be heat treated, so the seam is less treated, so the seam is less visible. visible.

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Production of seam Production of seam tubestubes

The process involves The process involves the progressive the progressive bending of metal strip bending of metal strip as it passes through a as it passes through a series of rollers at series of rollers at speed up to 80m/sec. speed up to 80m/sec. Only bending take Only bending take place, all bends are place, all bends are parallel. Seam welding parallel. Seam welding process carried out to process carried out to form a proper form a proper tube.and wed flashes tube.and wed flashes are removed by are removed by scarfing blades.scarfing blades.

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Compression of seamless Compression of seamless pipes &seam tubespipes &seam tubes

Seam less:Seam less:

1.1. Seamless pipe Seamless pipe provides the most provides the most reliable pressure reliable pressure retaining retaining characteristics.characteristics.

2.2. easily available than easily available than welded pipe.welded pipe.

3.3. More Expensive.More Expensive.

4.4. Size is less than 3 Size is less than 3 inch dia. inch dia.

Seam tube:Seam tube:

1.1. Welded pipe often Welded pipe often has tighter has tighter dimensional dimensional tolerances.tolerances.

2.2. cheaper if cheaper if manufactured in the manufactured in the same quantities.same quantities.

3.3. Size is greater than 3 Size is greater than 3 inch dia.inch dia.