ITM UNIVERSE

Rolling Process

Subject : Metal Forming Analysis By :

Pankil Shah (130950119115)Mech : B 7th Sem

Two High Rolling Mill

Rolling is a bulk deformation process in which the thickness of the work is reduced by compressive forces exerted by two opposing rolls. The rolls rotate to pull and simultaneously squeeze the work between them.

Introduction to Rolling

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The basic process shown in the previous figure is “Flat Rolling”, used to reduce the thickness of a rectangular cross section. A closely related process is “shape rolling”, in which a square cross section is formed into a shape such as an I-beam.

Shape Rolling

Flat Rolling

Shape Rolling

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After casting, ingots are rolled into one of three intermediate shapes called blooms, billets, and slabs:

• Blooms have square cross section 6” x 6” or larger. They are rolled into structural shapes.

• Billets have square cross section 1.5” x 1.5” or larger. they are rolled into bars and rods.

• Slabs have rectangular cross section 10” x 1.5” or larger. They are rolled into plates, sheets and strips.

•Plate is the product with a thickness > 6 mm.

•Sheet is the product with a thickness < 6 mm and width > 600 mm.

•Strip is the product with a thickness < 6 mm and width < 600 mm.

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Types of Rolling•Based on work piece geometry :

• Flat rolling - used to reduce thickness of a rectangular cross section

• Shape rolling - square cross section is formed into a shape such as an I‑beam

•Based on work temperature :

• Hot Rolling – most common due to the large amount of deformation required

• Cold rolling – produces finished sheet and plate stock

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Roll configurations in rolling mills

Two High Rolling Mill. Three High Rolling Mill

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Cluster Rolling Mill.

Tandem Rolling Mill.

Hot rolling

• Hot rolling is a metalworking process that occurs above the recrystallization temperature of the material.

• Hot rolled metals generally have little directionality in their mechanical properties and deformation induced residual stresses.

• However, in certain instances non-metallic inclusions will impart some directionality

• Hot rolling is used mainly to produce sheet metal or simple cross sections, such as rail tracks.

Cold rolling

•Cold rolling occurs with the metal below its recrystallization temperature (usually at room temperature).

•Due to smaller size of the work pieces and their greater strength than hot rolled stock, four-high or cluster mills are used. 

•Commonly cold-rolled products include sheets, strips and rods; products being smaller than the same products that are hot rolled.

Types of rolling processes

• Continuous

• Transverse

• Section or shape

• Ring

• Continuous casting and hot rolling • Thread

Continuous

• The objective is to decrease the thickness of the metal with anincrease in length and with little increase in width.

Transverse

• Using circular wedge rolls.• Heated bar is cropped to length andfed in transversely between rolls.• Rolls are revolved in one direction.

SECTION or SHAPE

• Flat slap is progressively bent into complex shapes.• Suitable for producing moulded sections such as irregular shaped channels and trim.

Ring

• A specialized type of hot rolling that increases the diameter of a ring. • The resulting grain structure is circumferential, which gives better mechanical properties.

Continuous casting and hot rolling

Metal is melted, cast and hot rolled continuously through a series of rolling mills within the same process.

Thread

Rolled threads are produced in a single pass at speeds far in excess of those used to cut threads. Dies are pressed against the surface of cylindrical blank. As the blank rolls against the in feeding die faces, the material is displaced to form the roots of the thread, and the displaced material flows radially outward to form the thread's crest.

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