Date post: | 06-Apr-2018 |
Category: |
Documents |
Upload: | khalidalkarim5852 |
View: | 220 times |
Download: | 0 times |
of 18
8/3/2019 Ind Us Pro Presentation 2
1/18
Classification of Forming
Processes
Mechanical and Metallurgical
Fundamentals and Rolling
Group 4
8/3/2019 Ind Us Pro Presentation 2
2/18
BMM 3643Page 2
Metal Forming
Metal forming is a shape production process(similar to casting)
But it uses the fundamental of deformation
processes. These processes is designed to exploit aproperty of engineering materials (mostlymetals) known as plasticity, the ability to flowas solids without deterioration of their
properties. Since all processing is done in the solid state,
there is no need to handle molten materials.
8/3/2019 Ind Us Pro Presentation 2
3/18
BMM 3643Page 3
The material is simply moved (or rearranged)to produce shape, then the amount of waste
is reduced substantially unlike cutting awayoperations.
Machinery and tooling can be expensive and
it is suitable for mass production.
8/3/2019 Ind Us Pro Presentation 2
4/18
BMM 3643Page 4
8/3/2019 Ind Us Pro Presentation 2
5/18
COMPRESSIVE FORMING: Rolling
Rolling is the process of reducing thickness (or
changing the cross section) of a long
workpiece by compressive forces appliedthrough a set of rolls.
The process of plastically deforming metal by
passing it between the rolls is known as rolling.
The work is subjected to high compressive
stresses from squeezing action of rolls.
8/3/2019 Ind Us Pro Presentation 2
6/18
BMM 3643Page 6
Grain Structure During
Hot RollingChanges in the grain structure of cast or of large-grain wroughtmetals during hot rolling. Hot rolling is an effective way to reducegrain size in metals, for improved strength and ductility. Caststructures of ingots or continuous casting are converted to a
wrought structure by hot working.
8/3/2019 Ind Us Pro Presentation 2
7/18
Forging of Metals
8/3/2019 Ind Us Pro Presentation 2
8/18
BMM 3643Page 8
Types of Forging Dies
Three types of forging dies:
1. Open-die forging - work is compressed betweentwo flat dies, allowing metal to flow laterallywithout constraint
2. Impression-die forging (closed) - die surfacescontain a cavity or impression that is imparted toworkpart, thus constraining metal flow -flash is
created
8/3/2019 Ind Us Pro Presentation 2
9/18
BMM 3643Page 9
Types of Forging Dies
(cont.)
F
lashless forging (precision forging)-
workpartis completely constrained in die and noexcess flash is produced
8/3/2019 Ind Us Pro Presentation 2
10/18
BMM 3643Page 10
The forging process can be depicted by asolid workpiece placed between two flat dies
and reduced in height by compressing it.
Common names include upsetting or upset
forging
Open-die Forging
8/3/2019 Ind Us Pro Presentation 2
11/18
BMM 3643Page 11
Open-die Forging
(c) Deformation with friction. Note barreling of the billet caused byfriction forces at the billet-die interfaces.
(a) Solid cylindrical billet upset between two flat dies.
(b) Uniform deformation of the billet without friction.
8/3/2019 Ind Us Pro Presentation 2
12/18
BMM 3643Page 12
Closed-die Forging
The workpiece acquires the shape of the die
cavities while being forged between two
shaped dies.
8/3/2019 Ind Us Pro Presentation 2
13/18
BMM 3643Page 13
Impression-Die Forging
(a) through (c) Stages in impression-die forging of a solid round billet. Note the
formation of flash, which is excess metal that is subsequently trimmed off(d)
Standard terminology for various features of a forging die.
8/3/2019 Ind Us Pro Presentation 2
14/18
BMM 3643Page 14
Die Forging
Advantages and Limitations
Advantages compared to machining fromsolid stock:
Higher production rates
Conservation of metal (less waste)
Greater strength
Favorable grain orientation in the metal
8/3/2019 Ind Us Pro Presentation 2
15/18
BMM 3643Page 15
Die Forging
Advantages and Limitations(cont.)
Limitations:
Not capable of close tolerances Machining often required to achieve
accuracies and features needed, such as
holes, threads, and mating surfaces thatfit with other components
8/3/2019 Ind Us Pro Presentation 2
16/18
BMM 3643Page 16
Precision Forging
(flashless) Special dies are used to produce parts having
greater accuracies.
L
ittle excess material on the forged part(flashless)
Process control is more demanding thanimpression-die forging.
Best suited to part geometries that are simpleand symmetrical.
8/3/2019 Ind Us Pro Presentation 2
17/18
BMM 3643Page 17
Cogging / Smithing
Cogging also called drawing out, is basically
an open-die forging operation.
It is a process of reducing the thickness of abar by successive forging steps at specific
interval.
Blacksmiths perform such operations with a
hammer and anvil using hot pieces of metals.
8/3/2019 Ind Us Pro Presentation 2
18/18
BMM 3643Page 18
Cogging
Two views of acoggingoperation on a
rectangular bar.Blacksmiths usethis process toreduce thethickness of bars
by hammering
the part on ananvil. Note the
barreling of theworkpiece.