Rolling

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The Hashemite University
Faculty of Engineering
Industrial Engineering Department

Manufacturing Processes Laboratory

ROLLING PROCESS EXP.
Experiment No.7
Done by: Ahmad Waheed Al Sayeh (1031159)
Section: Wed. (2-5)

Q1 Write the applications of the rolling process.
Roll bending produces a cylindrical shaped product from plate or steel
metal.
Roll forming is ideal for producing parts with long lengths or in large
quantities.
Ring rolling common applications: rockets, turbines, airplanes, pipes,
and pressure vessel.
Thread rolling : produces bolts & screws

Q2 Explain the types of the rolling process.
Roll bending: Roll bending produces a cylindrical shaped product from plate
or steel metal.

Roll forming:
Roll forming, roll bending or plate rolling is a continuous bending operation
in which a long strip of metal (typically coiled steel) is passed through
consecutive sets of rolls, or stands, each performing only an incremental
part of the bend, until the desired cross-section profile is obtained. Roll
forming is ideal for producing parts with long lengths or in large quantities.
There are 3 main processes: 4 rollers, 3
rollers and 2 rollers, each of which has as
different advantages according to the
desired specifications of the output plate.

Ring rolling: Ring rolling is a specialized
type of hot rolling that increases the
diameter of a ring. The starting material is
a thick-walled ring. This workpiece is
placed between two rolls an idler roll,
while another roll, called the driven roll,
presses the ring from the outside. As the
rolling occurs the wall thickness decreases
as the diameter increases. The rolls may be shaped to form various crosssectional shapes. The resulting grain structure is circumferential, which
gives better mechanical properties. Diameters can be as large as 8 m (26 ft)
and face heights as tall as 2 m (79 in). Common applications include
rockets, turbines, airplanes, pipes, and pressure vessels.

Thread rolling: 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. A blank is fed between two grooved die plates to form the threads.
The thread is formed by the axial flow of material in the work piece. The
grain structure of the material is not cut, but is distorted to follow the
thread form. Rolled threads are produced in a single pass at speeds far in
excess of those used to cut threads.

Shaped /section rolling: A special type of cold
rolling in which flat slap is progressively bent into
complex shapes by passing it through a series of
driven rolls. Suitable for producing molded sections
such as irregular shaped channels and trim. A
variety of sections can be produced by roll forming
process using a series of forming rollers in a
continuous method to roll the metal sheet to a
specific shape.

Q3 Mention rolling process defects & causes & solving.
1-Defects from cast ingot before rolling: Defects other than cracks can
result from defects introduced during the ingot stage of production.
Porosity, cavity, blow hole occurred in the cast ingot will be closed up
during the rolling process. Longitudinal stringers of non-metallic inclusions
or pearlite banding are related to melting and solidification practices. In
severe cases, these defects can lead to laminations which drastically reduce
the strength in the thickness direction.
2- Defects during rolling:
There are two aspects to the problem of the shape of a sheet.
1) Uniform thickness over the width and thickness – can be precisely
controlled with modern gage control system.
2) Flatness – difficult to measure accurately.

3- Possible effects when rolling
with insufficient camber: •
Thicker centre means the edges
would be plastically elongated
more than the centre, normally
called long edges. This induces
the residual stress pattern of
compression at the edges and tension along the centerline. This can cause
centerline cracking (c), warping (d) or edge wrinkling or crepe-paper effect
or wavy edge (e).

4-Possible effects when rolls are over-cambered: Thicker edges than the
centre mean the centre would be plastically elongated more than the
edges, resulting in lateral spread. The residual stress pattern is now under
compression in the centerline and tension at the edges

Q4 How you can develop the rolling machine?
Make it automated.
Reduce the friction by using the lubrications.
Reduce the space between the rolls to give lower thickness.

Q5 Write your conclusion.
* Rolling is a metal forming process in which metal stock is passed through
a pair of rolls. Rolling is classified according to the temperature of the metal
rolled. If the temperature of the metal is above
its recrystallization temperature, then the process is termed as hot rolling.
If the temperature of the metal is below its recrystallization temperature,
the process is termed as cold rolling. In terms of usage, hot rolling
processes more tonnage than any other manufacturing process, and cold
rolling processes the most tonnage out of all cold working processes.
* Rolling processes is a widely used in industries which take a main role in
different kinds of products.

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