Basic one of the oldest metalworking processes. It

Basic
information about forging:-

 

1.    
Introduction

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            Forging is one
of the oldest metalworking processes. It was performed by a smith and anvil,
though introducing water power to the production and working of iron in 12th
century allowed the use of large trip hammer that exponential increased amount
and size of iron that could be produced and forged easily. The forge has
evolved over centuries to become facility with engineer process, production
equipment, tooling, raw materials and products to demand in industry.

            Now a day’s forge is done either with hammer powered by
compressive air or presses, electricity, steam. Some steam hammer remains in
use but they become obsolete with the other, more convenient, power sources. Hammer
may have reciprocating weights in thousands of pounds.

                Forging is a manufacturing process
involving the shapes of metals using localized compressive forces. The blows are providing with a hammer or a die. Its classified
according to the temperature at which its performed examples:- cold forging,
warm forging, hot forging etc. forge weight parts can be from less than one
kilogram to the hundreds of  metric tons.
There are different products which can be produce from the forge were hardware,
kitchen ware, edge weapons, hand tools, jewelry and cymbals. Its parts are
widely used in machines and mechanisms for the components required high
strength. Forging usually requires future processing (like machining) to
achieve a finished parts.

 

Die
forging :-

            Die forging is divided into two types :-

1)      Open
die forging

2)      Closed
die forging

 

Ø  Open
die forging:-

The
shaping of heated metal parts between a top die attached to a ram and a bottom
die attached to a hammer, anvil. metal parts are work at their appropriate
temperature, ranging from 500 F to 2400 F and gradually shaped into desired
configuration through the skill hammering of work piece.

 Benefits

1)     
Improve microstructure

2)     
Continuous grain flow

3)     
Finer grain size

4)     
Reduce chance of voids

 

 

 

 

 

 

 

 

Ø  Closed
die forging process:-

 

In
closed die forging process the dies move towards each other
and cover the work piece in whole or in part. It’s also called an impression
die forging process. In impression-die forging, the metal is placed in
a die resembling a
mold, which is attached to an anvil. Usually, the hammer die is shaped as well. The hammer
is then dropped on the work piece, causing the metal to flow and fill the die cavities.

 

 

 

 

 

 

 

Aim:-

            The
aim of the work is to develop a technological process and to analyze the
forging process of the chosen product. The work will includes setting
parameters of the forging process and technological possibilities for the
selected products.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.     History of forging development

 

The
history of forging metal spring from the land between Tigris and Euphrates
which is called Mesopotamia. Forging metal working date back was about 4500
B.C. inhabitant of this fertile valley were the Sumerians. These people, which
is mixture of many ethnic background, were the real founders of metallurgy as
we know in todays life.

 

The
imagination or art of forging, shaping the metal using eat and pressure,
progressed until the dark ages. Same time most of industrial, scientific and
cultural advancement halted. Before this possession of metals was highly
regarded as a wealth. The Romans even had goods dedicated to the forge. At dark
ages the production of weapons flourished. European culture and industry was
several set back due to constant wars. The iron industry remained much intact
due to the requirement for weapons.

 

The
most significant development came from combination of the roman discover of
water power and forging of metals. Water power was used to operate and
mechanical hammers. This discover came into use between the 10th and
12th century A.D. few water operated hammer were still being used in
20th century. In 19th century invention of steam engine
brought to the doorstep of the modern forging. The harnessing of electrical
power and development of explosive forming, which truly brought forging out of
the dark ages.

 

Forging
as an art form started with the desire to produce decorative objects from
precious metals. Today, forging is a major world-wide industry that has
significantly contributed to the development of man.

            In 19th century forge
smith were particular skilled at hand and open die forging of wrought iron was
only produced in high heat, the smith became skillful in hammer welding and
large  shaft forgings weighing 10 tons
and more were gradually built up by a process of forging. The Bessemer steel
making process was invented in 1856 was a major breakthrough for the ferrous
forging industry. The forgers now had a huge supply of low cost steel for
production of  quantities of forgings.

 

Damascus steel :-

            Damascus
steel was a kind of steel utilized for assembling sword cutting edges in the
Near East made with wootz steel. These swords are characterized
by distinctive patterns banding and mottling reminiscent of streaming
water. Such edges were presumed to be intense, impervious to shattering, and
equipped for being sharpened to a sharp, versatile edge. The steel is named
after Damascus, the capital city of Syria. It might either allude to swords
made or sold in Damascus specifically, or it might simply allude to the part of
the common place examples, by correlation with Damask textures.

 

The
first strategy for creating Damascus steel isn’t known. Present day endeavors
to copy the metal have not been totally fruitful because of contrasts in crude
materials and assembling methods. A few people in present day times have
asserted that they have rediscovered the techniques by which the first Damascus
steel was created.

 

The
notoriety and history of Damascus steel has offered ascend to numerous legends,
for example, the capacity to trim through a rifle barrel. An exploration group
in Germany distributed a report in 2006 uncovering nanowires and carbon
nanotubes in a sharp edge produced from Damascus steel. Albeit many kinds of
present day steel outflank old Damascus compounds, synthetic responses in the
creation procedure made the cutting edges unprecedented for their opportunity,
as Damascus steel was superplastic and hard in the meantime. Amid the purifying
procedure to get Wootz steel ingots, woody biomass and leaves are referred to
have been utilized as carburizing additives alongside certain particular kinds
of iron rich in micro alloying components. These ingots would then be
additionally produced and worked into Damascus steel cutting edges. Research
now demonstrates that carbon nanotubes can be gotten from plant strands,
recommending how the nanotubes were framed in the steel. A few specialists hope
to find such nanotubes in more relics as they are dissected all the more
intently.

 

 

3.     Review of existing solutions for
die forging

 

v  Types
of forging processes :-

 

1)     
Precision forging

2)     
Cold forging

3)     
Hot forging

4)     
Roll forging

5)     
Seamless rolled ring forging

 

Precision
forging :-

            Precision forging is the most popular technology for
producing parts from expensive materials. Numerical and physical modeling
methods contribute to the development of new technologies of forging for
manufacturing products with difficult shapes, especially for the automotive
industry, e.g. cold forging of gear wheels.

            The main problem in the production of CVJ is correct
manufacture of the outer race – casing, particularly because of their irregular
shape. Currently precision forging with hot multi-operation forging in closed
dies with a complex deformation scheme is used in mass production. In forging
process of CVJ casing problem is the low durability of tools. Not far ago the
most common forging defect was abrasive wear and fracture of die.

                        Precision forging is applied to
rotational symmetric parts as it does simplify the process and tool design.
Higher accuracy of the rotational parts can be achieved. This procedure is
usually realized through single or double stage forming operations with other
side in case of nonsymmetrical forgings it is more difficult to gain the
criteria of this technology due to multistage forming that should be employed.
In multistage precision forging each individual station is used for a simple
basic operation, such as heading, upsetting.

 

 

Cold
forging:-

            It’s defined as
forming of a bulk material at room temperature with no initial heating of the
preform stages. Cold extrusion is special type of forging process where the
cold metal flow plastically under compressive forces into a variety of shapes.
The terms cold forging are often used interchangeably and refer to well-known
forming operation such as upsetting, extrusion, ironing, swaging, and coining.
This process are usually performed in mechanical or hydraulic presses. Several
steps are used to produce a final part geometry, starting with a slag of simple
shape. These technique a very large number of parts can be produced.

            There are few advantages of these process are :-

1)     
Excellent dimensional tolerance and
surface finish for forge parts.

2)     
High production rates

3)     
Significant sawing in material and
machining

 

 

      For cold forging materials are all metals
that exhibit ductility at room temperature can be cold forge. This consist primarily
of
steels and aluminum alloys , alloy of copper, zinc, tin, titanium, and nickel
are also cold forge for special application. Stainless steel usually are not
easily forged. Cold forging of austenite steels require high forces and tool
pressures, its difficult to lubricates.

 

 

 

 

 

Hot
forging :-

            In addition to
isothermal forging, hot-die hydraulic press forging is also widely used for
producing aerospace components. The die temperatures used in hot-die forging
are usually a few hundred degrees lower than the work piece temperature.
However, they are much higher than the die temperatures used in conventional
forging, ranging from 400 to 800 F (205 to 425 C). Higher die temperatures
require stronger materials for the dies.

 Super alloys are often used as die materials
for hot-die forging. To keep a constant high temperature of the dies,
consistent heating of the die is required. Induction, resistance, and radiant
systems are usually used for die heating in hot-die forging. The strain rate
used is usually an order of magnitude higher than that used in isothermal
forging, to reduce die chilling. Due to the higher strain rates used in hot-die
forging, P/M super alloys are usually not forged by this process. On the other
hand, titanium alloys and cast and wrought super alloys are often forged by
hot-die forging processes.

     

 

 

 

 

 

4.     Product description

The process is realized
in three operations on theP-1800 T press. The first operation is the upset
forging, the second forging die, third finish forging. The forging material is
C45 steel, the preform has dimensions : diameter 55mm, length 95mm, weight 1.77
kg. the initial temperature of the forging preform is 1150 (forging
temperature). The operation diagram is shown in figure.

 

First operation I upset forging

 
(upsetting the flat tools for height 27 mm)
 

Second operation
Forging

Third operation Finish
forging

Forging after cutting

Fig. 2 Forgings after
forging operations

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5.     Describe material C45 steel

Chemical composition of
C45 steel (wt.%)

C

Si

Mn

S

P

Cr

Ni

Cu

Mo

Ti

V

W

0.42

0.24

0.69

0.019

0.016

0.12

0.16

0.12

0.02

0.002

0.004

0.01

 

An
important measure in steel processing industry is achieving the required
mechanical properties and microstructure of the material. A new phenomenon has
been discovered recently which allows to refine ferrite grain significantly and
to spheroids carbides over a very short time compared to conventional heat
treatment techniques. The newly developed technology based on the ASR effect
consists in heating a steel work piece through thickness to a temperature no
higher than Ac1 and in subsequent plastic deformation. The energy introduced
through plastic deformation causes the work piece temperature to increase. This
temperature increase, however, is not uniform throughout the work piece
cross-section, leading to substantial inhomogeneity. Fully austenitized regions,
partially austenitized regions, and areas where no phase transformation
occurred, coexist. In locations previously subjected to intensive plastic
deformation, cementite lamellae disintegrate and globular carbides form. In
regions subjected to milder plastic deformation, spheroidisation does not occur
directly in the course of the thermo mechanical treatment. Despite, the
cementite lamellae show a stronger tendency to spheroidise during subsequent
annealing. The combination of a suitable pre-heating temperature, an
appropriate amount of strain and a possible reheating leads to transformation
of initial ferrite-pearlite microstructure with lamellar pearlite into desired
ferrite matrix with spheroidised carbides. Key microstructure parameters
governing the properties of ferrite-pearlite steels include exactly the ferrite
grain size, the distribution of defects within the ferrite grain and the
distribution and morphology of carbides. The present article describes a new
thermo mechanical treatment technique which allows controlling these
microstructure parameters and related mechanical properties in order to achieve
their favorable combination in structural carbon steel C45. The processing time
is very short when compared to several-hour conventional heat treatments. This
offers potential for achieving desired mechanical properties with time and
energy savings.

The
experimental programmed was performed using structural carbon steel C45 with
the chemical composition listed in Table 1. The initial microstructure
consisted of ferrite and lamellar pearlite with pronounced banding along the
axis of the bar stock. Hardness of the as-received material was 180 HV, 0.2
proof stress 378 MPa, ultimate tensile strength 673 MPa, elongation A5=29% and
impact toughness KCV=42 J/cm2 .

The
specimens were processed in an atmosphere furnace and plastically deformed
between flat swages of a hydraulic press. Metallographic structure observation
was performed on longitudinal sections of all specimens in order to examine and
to compare microstructures throughout the specimen cross-section. The
microstructure was observed using light and scanning electron microscopes.
Vickers HV30 hardness was measured on specimens. Specimens with the gauge
length of 20 mm and a diameter of 4 mm were used for tensile testing. Charpy
impact test was carried out using miniature specimens with the dimensions of
3×4×27 mm with a 1 mm-deep V-notch.

 

 

 

 

 

 

 

 

 

Technological
process

 

          The demand of
customers for individual solutions are increasing constantly now a days,
specially from the automotive industry. Despite the platform to the gaining of
overall and modern design of automobile manufactures, the industry are faced
with producing a huge number of variants of aluminum forging, increasingly
difficult parts, high costs steel and sagging prices.

            Its also affect in development of equipment suppliers. We
have to offend different units in products range to provide for more difficult
forging operations. They are also in require for increased use of suitable
pre-forging units, which offer a potential for saving materials.

            This discussion covers new development in pre-forming
technology and hammers of automation, new drive concepts designed for reduce
the contact time and new generation of control system. The number of automated
live will increased all products. this required forging of very different parts
with a single forging line at a high degree of automation and better cost than
other/perform ratio.

·        
Pre-forming forging :-

There
are many different processes available from Mullier Weingarten for pre-forming aluminum
or steel forging.

 

·        
Continuous pre-forming :-

In this continuous pre-forming method,
the forging is given a defined pre-shaped in single forming movement. In this
process offers the advantages, especially for aluminum the short process
involves in little cooling for the component and high cycle time can be reach.
The disadvantages is that the degree of forming is often limited in pre-forming
process.

 

·        
Discontinues pre-forming:-

In this method is characterized by
producing a pre shape by means of several forming movements, typically forming
equipment used for this process is roll reduces. This is the case if several
pre-forming phases are necessary, e.g. bending and upsetting. The advantages is
that it may be necessary to re- heat the work-piece especially in aluminum,
before the main forging phase.

 

·        
Cross roll forming :-

In this method is characterized by rotating
movements of the work piece between two-rolls or vertically reciprocating
plates rolling a contour into the work piece with matched profiled tools. This
specific tool contour produces a taper in work-piece, with the material being
mainly pressed from middle part of work piece towards the ends.

            Speeds for steels and aluminum can be 600mm/sec. to flow
the resistance of work piece material during the forming process makes it
necessary to minimize any torsion of work piece during rolling. Homogenous distribution
around the neutral lies by suitable to design of the tools. For obtain of a
reliable process for aluminum forging, a new-generation of cross-roll was
developed on basis of Bah design. In this high priority is giving to controlled
tool heating on a rotating tool holder by adding electrical heating cartridge
to maintain the temperature. The cartridges are design so they can be
automatically coupled during die changes.

Ø Technological modeling of C45 steel

This
modeling is based on thermo-mechanical treatment of a small amount of real
material using a thermo-mechanical simulator. This procedure allow quick and
accurate changes of selected parameters of thermo-mechanical treatment, due to
this high dynamics of the process. The current state of technology also allows
the use of this method for die forging.

Its
focused on the issues of material technological modeling of die forging made
from C45 steel. The possibility of its application to design changes and
optimization of heat treatment and forming technological model for real
forging. This phase was o achieve the desired agreement between the real
forging and model. The aim of controlled cooling from the forging temperature
was to achieve structure without heat treatment, which is currently a necessary
part of manufacturing process.

Creation in the die
forgings depends on a mix of a few progressive operations which can be
partitioned into three fundamental advances: warming to the framing
temperature, dynamic shaping and resulting heat treatment, which serve to
accomplish the coveted microstructure which gives the producing its mechanical
properties. Warmth treatment is a regular technique for accomplishing the
coveted properties, however it gives the maker costs as far as vitality
utilization and time and various different segments of the assembling costs.
This is the reason we have endeavored to acquire the coveted properties of
forgings without the utilization of warmth treatment. Material-mechanical
displaying is an exceptionally successful device when growing such methodology.
This approach utilizes the preparing of little volumes of material which are
subjected to handling conditions near the genuine states of the real
innovations. This can viably improve the vast majority of the fundamental  elements of the innovation, without intruding
on the creation process, and without assigning time for research and
advancement of generation offices via doing experimentation testing amid
operation.