high velocity forming
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Seminar Seminar
onon
Thapar University, Patiala(Department of Mechanical Engineering)
Presented by:Presented by:Gopal Krishan DixitGopal Krishan DixitRoll No. – 800882001Roll No. – 800882001
M.E.(Prod. & Inds. Engg.)M.E.(Prod. & Inds. Engg.)
• Sheet metal forming is a process that materials
undergo permanent deformation by cold
forming to produce a variety of complex three
dimensional shapes.
SHEET METAL FORMING
HIGH VELOCITY FORMINGHIGH VELOCITY FORMING
High velocity forming processes began to make High velocity forming processes began to make
their mark and grow in application in 1960.their mark and grow in application in 1960.
Requirements such as the introduction of super Requirements such as the introduction of super
tough alloys for space vehicles., supersonic aircraft tough alloys for space vehicles., supersonic aircraft
and the need for shaping incredibly small, thin and and the need for shaping incredibly small, thin and
brittle materials for electronic components helped brittle materials for electronic components helped
in the growth of high velocity forming processes. in the growth of high velocity forming processes.
In high velocity forming of metals, the metal is In high velocity forming of metals, the metal is
shaped in micro-seconds with pressures generated shaped in micro-seconds with pressures generated
by the sudden application of large amounts of by the sudden application of large amounts of
energy.energy.
HIGH VELOCITY FORMINGHIGH VELOCITY FORMING
Pressures needed for forming are Pressures needed for forming are
generated by :generated by :
1.1. Detonating explosives.Detonating explosives.
2.2. Releasing compressed gases.Releasing compressed gases.
3.3. Discharging powerful electrical sparks orDischarging powerful electrical sparks or
4.4. Electromagnetic energy.Electromagnetic energy.
Explosive formingExplosive forming
Electro-hydraulic forming.Electro-hydraulic forming.
Magnetic formingMagnetic forming
Pneumatic- mechanical high velocity forging..Pneumatic- mechanical high velocity forging..
TYPES OF HIGH VELOCITY TYPES OF HIGH VELOCITY FORMING PROCESSESFORMING PROCESSES
EXPLOSIVE EXPLOSIVE FORMINGFORMING
Explosive forming has evolved as one of the most dramatic Explosive forming has evolved as one of the most dramatic
of the new metalworking techniques. Explosive forming is of the new metalworking techniques. Explosive forming is
employed in Aerospace and aircraft industries and has been employed in Aerospace and aircraft industries and has been
successfully employed in the production of automotive-successfully employed in the production of automotive-
related components. Explosive Forming can be utilized to related components. Explosive Forming can be utilized to
form a wide variety of metals, from Aluminium to high form a wide variety of metals, from Aluminium to high
strength alloysstrength alloys
EXPLOSIVE FORMINGEXPLOSIVE FORMING
In this process the punch is replaced by an explosive charge. In this process the punch is replaced by an explosive charge.
The process derives its name from the fact that the energy The process derives its name from the fact that the energy
liberated due to the detonation of an explosive is used to form liberated due to the detonation of an explosive is used to form
the desired configuration. The charge used is very small, but the desired configuration. The charge used is very small, but
is capable of exerting tremendous forces on the work piece.is capable of exerting tremendous forces on the work piece.
In Explosive Forming chemical energy from the explosives is In Explosive Forming chemical energy from the explosives is
used to generate shock waves through a medium (mostly used to generate shock waves through a medium (mostly
water), which are directed to deform the work piece at very water), which are directed to deform the work piece at very
high velocities.high velocities.
EXPLOSIVE FORMINGEXPLOSIVE FORMING
Explosive forming makes use of the pressure wave Explosive forming makes use of the pressure wave
generated by an explosion in a fluid to force the generated by an explosion in a fluid to force the
material being formed against the walls of the material being formed against the walls of the
female die. The fluid has the effect of rounding off female die. The fluid has the effect of rounding off
the pressure pulse generated by the detonation. the pressure pulse generated by the detonation.
Methods of Explosive Methods of Explosive FormingForming
The explosives are used in many forms- rod, sheet, The explosives are used in many forms- rod, sheet,
granules, liquid, stick etc. Depending upon the placement granules, liquid, stick etc. Depending upon the placement
of the explosive (charge), the operations fall into two of the explosive (charge), the operations fall into two
categories :categories :
Stand-off operations.Stand-off operations.
Contact operations.Contact operations.
Methods of Explosive FormingMethods of Explosive Forming
Standoff MethodStandoff Method
In this method, the explosive charge is located at some In this method, the explosive charge is located at some
predetermined distance from the work piece and the energy is predetermined distance from the work piece and the energy is
transmitted through an intervening medium like air, oil, or transmitted through an intervening medium like air, oil, or
water. Peak pressure at the work piece may range from a few water. Peak pressure at the work piece may range from a few
thousand psi to several hundred thousand psi depending on thousand psi to several hundred thousand psi depending on
the parameters of the operation.the parameters of the operation.
METHODS OF METHODS OF EXPLOSIVE FORMINGEXPLOSIVE FORMING
Contact MethodContact Method
In this method, the explosive charge is held in In this method, the explosive charge is held in
direct contact with the work piece while the direct contact with the work piece while the
detonation is initiated. The detonation produces detonation is initiated. The detonation produces
interface pressures on the surface of the metal up to interface pressures on the surface of the metal up to
several million psi (35000 MPa).several million psi (35000 MPa).
METHODS OF EXPLOSIVE METHODS OF EXPLOSIVE FORMINGFORMING
WORKING PRINCIPLEWORKING PRINCIPLE
The system used for Standoff The system used for Standoff
operation consists of following operation consists of following
parts: -parts: -
1) An explosive charge1) An explosive charge
2) An energy transmitted 2) An energy transmitted
mediummedium
3) A die assembly3) A die assembly
4) The work piece.4) The work piece.
- - Figure 1Figure 1 shows an arrangement of Standoff Explosive shows an arrangement of Standoff Explosive
forming operation. The die assembly is put together on the forming operation. The die assembly is put together on the
bottom of the tank. Work piece is placed on the die and blank bottom of the tank. Work piece is placed on the die and blank
holder placed above. A vacuum is then created in the die cavity. holder placed above. A vacuum is then created in the die cavity.
The explosive charge is placed in position over the centre of the The explosive charge is placed in position over the centre of the
work piece. The explosive charge is suspended over the blank at work piece. The explosive charge is suspended over the blank at
a predetermined distance. The complete assembly is immersed in a predetermined distance. The complete assembly is immersed in
a tank of water. a tank of water.
- After the detonation of explosive, a pressure pulse of high - After the detonation of explosive, a pressure pulse of high
intensity is produced. A gas bubble is also produced which intensity is produced. A gas bubble is also produced which
expands spherically and then collapses until it vents at the expands spherically and then collapses until it vents at the
surface of the water. When the pressure pulse impinges against surface of the water. When the pressure pulse impinges against
the work piece, the metal is displaced into the die cavitythe work piece, the metal is displaced into the die cavity
WORKING PRINCIPLEWORKING PRINCIPLE
Explosives are substances that undergo rapid chemical Explosives are substances that undergo rapid chemical
reaction during which heat and large quantities of gaseous reaction during which heat and large quantities of gaseous
products are evolved.products are evolved.
Explosives are divide into two classes;Explosives are divide into two classes;
- Low Explosives in which the ammunition burns rapidly rather Low Explosives in which the ammunition burns rapidly rather
than exploding, hence pressure build up is not large.than exploding, hence pressure build up is not large.
- High Explosive which have a high rate of reaction with a large High Explosive which have a high rate of reaction with a large
pressure build up. pressure build up.
EXPLOSIVESEXPLOSIVES
Various explosives used are:Various explosives used are:
Solid (TNT-trinitro toluene)Solid (TNT-trinitro toluene)
Liquid (Nitroglycerine) Liquid (Nitroglycerine)
Gaseous (oxygen and acetylene mixtures). Gaseous (oxygen and acetylene mixtures).
EXPLOSIVESEXPLOSIVES
Low capital investment is required to adapt the process to Low capital investment is required to adapt the process to
production. production.
Large and expensive presses are not needed for forming. Large and expensive presses are not needed for forming.
Component is generally formed in one shot only.Component is generally formed in one shot only.
Only one die – either male or female is needed. For this reason Only one die – either male or female is needed. For this reason
tooling costs are greatly reduced.tooling costs are greatly reduced.
In general terms, the ultimate strength and yield strength are In general terms, the ultimate strength and yield strength are
improved by high explosive forming.improved by high explosive forming.
Large size parts unable to be handled successfully by Large size parts unable to be handled successfully by
conventional presses can be formed easily.conventional presses can be formed easily.
Advantages of Explosive FormingAdvantages of Explosive Forming Over Conventional formingOver Conventional forming
Personnel must be highly trained in the safe Personnel must be highly trained in the safe
handling of high explosives.handling of high explosives.
The technique has not been developed to the The technique has not been developed to the
stage where a part can always be formed on the stage where a part can always be formed on the
first shot.first shot.
The noise developed during forming and the The noise developed during forming and the
strict laws prohibiting the use of high explosives strict laws prohibiting the use of high explosives
in populated areas, usually make it necessary to in populated areas, usually make it necessary to
locate the facility away from populated areas. locate the facility away from populated areas.
This increase transportation and handling costs. This increase transportation and handling costs.
Disadvantages of Explosive Disadvantages of Explosive Forming Over Conventional Forming Over Conventional
formingforming
UsesUses
Blanking Coining Powder Blanking Coining Powder compacting compacting
Cutting Embossing Drawing Cutting Embossing Drawing Expanding Flanging Sizing Expanding Flanging Sizing
etc.etc.
ApplicationsApplications
Aerospace components. Aerospace components.
ELECTRO ELECTRO
HYDRAULIC HYDRAULIC
FORMING (EHF)FORMING (EHF)
The ability to generate high intensity shock waves by discharging stored The ability to generate high intensity shock waves by discharging stored
electrical energy across electrodes submerged in a liquid medium has been electrical energy across electrodes submerged in a liquid medium has been
recognized for a great many years. recognized for a great many years.
Spark discharge in a liquid was pointed out as a potential source of power Spark discharge in a liquid was pointed out as a potential source of power
in 1944. in 1944.
Basic research on under water condenser discharges was the subject of Basic research on under water condenser discharges was the subject of
several investigations in the early 1950’s.several investigations in the early 1950’s.
The first attempts to use electro hydraulic forming ( also called capacitor The first attempts to use electro hydraulic forming ( also called capacitor
discharge forming or spark forming ) process for forming metals were in discharge forming or spark forming ) process for forming metals were in
the United States in 1953 to punch holes in 1.5 mm steel plates. the United States in 1953 to punch holes in 1.5 mm steel plates.
INTRODUCTIONINTRODUCTION
PRINCIPLE OF OPERATIONPRINCIPLE OF OPERATION
Electro hydraulic forming involves the conversion of Electro hydraulic forming involves the conversion of
electrical energy to mechanical energy in a liquid medium. electrical energy to mechanical energy in a liquid medium.
Discharging of an electric spark in a liquid produces shock Discharging of an electric spark in a liquid produces shock
waves and pressures which can be used for metal forming. waves and pressures which can be used for metal forming.
As the energy produced is less than that produced in As the energy produced is less than that produced in
explosive forming, it is usually necessary to repeat the explosive forming, it is usually necessary to repeat the
operation several times to achieve the desired resultsoperation several times to achieve the desired results
METHODS TO CONVERT ELECTRICALMETHODS TO CONVERT ELECTRICAL
ENERGY INTO MECHANICAL ENERGY ENERGY INTO MECHANICAL ENERGY
Capacitor discharge through a gap :Capacitor discharge through a gap : Voltages of Voltages of
10,000 to 30,000 volts are generally used when the 10,000 to 30,000 volts are generally used when the
spark discharge method is utilized. This potential spark discharge method is utilized. This potential
difference will jump the air gap present between two difference will jump the air gap present between two
electrodes, submerged in the liquid.electrodes, submerged in the liquid.
METHODS TO CONVERT ELECTRICAL ENERGY METHODS TO CONVERT ELECTRICAL ENERGY
INTO MECHANICAL ENERGYINTO MECHANICAL ENERGY
Capacitor discharge through a wire :Capacitor discharge through a wire : provides better control than the provides better control than the
previous method because the path of the electrical discharge can be previous method because the path of the electrical discharge can be
positively determined and shaped, also a more efficient energy conversion positively determined and shaped, also a more efficient energy conversion
results. Moreover, with wire method, the use of lower potential difference is results. Moreover, with wire method, the use of lower potential difference is
possible; the wire will initiate a path across a wider gap than a specified possible; the wire will initiate a path across a wider gap than a specified
voltage will jump without the wire. A disadvantage of the wire method, voltage will jump without the wire. A disadvantage of the wire method,
however, is that a new wire is to be loaded after each shot for parts however, is that a new wire is to be loaded after each shot for parts
requiring multiple shots for reaching the desired results.requiring multiple shots for reaching the desired results.
In electrohydrauylic forming, electrical energy replaces the explosive used In electrohydrauylic forming, electrical energy replaces the explosive used
in explosive forming. High voltage electrical energy is discharged from a in explosive forming. High voltage electrical energy is discharged from a
capacitor bank (a device used to store electrical energy) into a thin wire or capacitor bank (a device used to store electrical energy) into a thin wire or
foil suspended between two electrodes. The unit is immersed in water. As foil suspended between two electrodes. The unit is immersed in water. As
the water vaporizes, the vapour products expand converting the electrical the water vaporizes, the vapour products expand converting the electrical
energy to hydraulic energy. The shock wave forms (or shapes) the metal energy to hydraulic energy. The shock wave forms (or shapes) the metal
against the die. against the die.
Since the energy produced for forming is less than that associated with Since the energy produced for forming is less than that associated with
explosives, it is usually necessary to repeat the operations several times to explosives, it is usually necessary to repeat the operations several times to
achieve the desiredachieve the desired resultsresults
ADVANTAGES OF EHF OVER ADVANTAGES OF EHF OVER CONVENTIONAL CONVENTIONAL
FORMING:FORMING: Many designs requiring standard operations have some Many designs requiring standard operations have some
peculiarity which is not within the capability of conventional peculiarity which is not within the capability of conventional
equipment, at least not without some special provision or equipment, at least not without some special provision or
tooling. Such works can be easily undertaking by EHF. tooling. Such works can be easily undertaking by EHF.
When EHF is used, the cost of tooling will almost always be less When EHF is used, the cost of tooling will almost always be less
than that for conventional equipment. than that for conventional equipment.
Large amounts of energy can be directed into isolated areas as Large amounts of energy can be directed into isolated areas as
required in some piercing operations. required in some piercing operations.
Reproducibility is another main advantage. Reproducibility is another main advantage.
DISADVANTAGES OF EHF DISADVANTAGES OF EHF
One of the most significant limitations of the process is the One of the most significant limitations of the process is the
energy rating of the capacitor bank itself, and the amount energy rating of the capacitor bank itself, and the amount
of energy which can be dumped by the triggering device is of energy which can be dumped by the triggering device is
another. another.
Materials having critical impact velocities below 30 meters Materials having critical impact velocities below 30 meters
per second are not practical for electohydraulic forming. per second are not practical for electohydraulic forming.
Neither is EHF of parts from materials having low Neither is EHF of parts from materials having low
ductility, such as the titanium alloys, likely to be successful. ductility, such as the titanium alloys, likely to be successful.
APPLICATIONS OF EHF:APPLICATIONS OF EHF:
A wide range of part sizes are producible by A wide range of part sizes are producible by
EHF, and most materials can be worked. EHF, and most materials can be worked.
The process is widely accepted in aerospace The process is widely accepted in aerospace
industries to accomplish bulging , forming, industries to accomplish bulging , forming,
beading, drawing, blanking and piercingbeading, drawing, blanking and piercing. .
MAGNETIC PULSE MAGNETIC PULSE FORMING(MPF)FORMING(MPF)
One of the earliest developments in producing a short One of the earliest developments in producing a short
duration, high intensity magnetic field was reported in 1924. A duration, high intensity magnetic field was reported in 1924. A
special storage battery was used as the energy source.special storage battery was used as the energy source.
Harvey and Brower, around 1958, demonstrated the Harvey and Brower, around 1958, demonstrated the
application of a magnetic system for forming metals. application of a magnetic system for forming metals.
In 1962, first magnetic commercial forming machine was In 1962, first magnetic commercial forming machine was
marketedmarketed
Using this technique, it is possible to apply to a metallic work Using this technique, it is possible to apply to a metallic work
piece a powerful, uniform magnetic pulse to swage and expand piece a powerful, uniform magnetic pulse to swage and expand
tubular forms, as well as to coin, shear and form flat sheets.tubular forms, as well as to coin, shear and form flat sheets.
INTRODUCTION
PRINCIPLE OF OPERATION:
A basic magnetic pulse metal A basic magnetic pulse metal
forming circuit consists of forming circuit consists of
-An energy storage -An energy storage
capacitor, capacitor,
-A switch-A switch
-A coil-A coil
-A power supply that -A power supply that
provides energy to charge a provides energy to charge a
capacitorcapacitor
FIGURE : Schematic illustration of the magnetic-pulse-forming process. The part is formed without physical contact without physical contact with any object
PRINCIPLE OF OPERATION:
An insulated induction coil is either An insulated induction coil is either
wrapped around, or placed within the wrapped around, or placed within the
work, depending on whether the work work, depending on whether the work
piece (metal) is required to be piece (metal) is required to be
squeezed inward or bulged outward. squeezed inward or bulged outward.
The coil is shaped to produce the The coil is shaped to produce the
desired shape in the work. desired shape in the work.
The power source is a capacitor bank. The power source is a capacitor bank.
Magnetic pulse forming machines Magnetic pulse forming machines
generate the very high currents generate the very high currents
required to produce the magnetic required to produce the magnetic
fields by discharging the capacitor fields by discharging the capacitor
bank through the coil.bank through the coil.
As a very high momentary currents are passed As a very high momentary currents are passed
through the coil an intense magnetic field is through the coil an intense magnetic field is
developed that causes the work to collapse, developed that causes the work to collapse,
compress, shrink or expand depending upon the compress, shrink or expand depending upon the
designs and placement of the coil. designs and placement of the coil.
Energy storage capacity and ability of the unit to Energy storage capacity and ability of the unit to
utilize that energy determines the size of the work utilize that energy determines the size of the work
that can be formed. Highly conductive metals can that can be formed. Highly conductive metals can
be formed easily. Non conductive or low be formed easily. Non conductive or low
conductivity materials can be formed if they are conductivity materials can be formed if they are
wrapped or coated with a high conductivity wrapped or coated with a high conductivity
auxiliary material. auxiliary material.
ADVANTAGES OF MPF OVER ADVANTAGES OF MPF OVER CONVENTIONAL FORMING:CONVENTIONAL FORMING:
The pressure is applied to the work piece through the The pressure is applied to the work piece through the
medium of a magnetic field without any physical medium of a magnetic field without any physical
contact.contact.
Since no static forces are involved in the process, Since no static forces are involved in the process,
relatively high structures may be used for the support relatively high structures may be used for the support
of dies.of dies.
Since there is no friction between the magnetic field Since there is no friction between the magnetic field
and the work piece, no lubricants are required and the and the work piece, no lubricants are required and the
process leaves no tool marks.process leaves no tool marks.
Machines can be designed for repetition rates of Machines can be designed for repetition rates of
hundreds of operations per minute.hundreds of operations per minute.
LIMITATIONS OF MPF :LIMITATIONS OF MPF :
The configuration of the work piece must be such The configuration of the work piece must be such
that the area to be formed constitutes a closed that the area to be formed constitutes a closed
loop, as in the case of rings, tubes, circular areas loop, as in the case of rings, tubes, circular areas
on flat work pieces etc., thus permitting the on flat work pieces etc., thus permitting the
induced currents to flow. Slits interrupting the induced currents to flow. Slits interrupting the
paths of the induced currents have a detrimental paths of the induced currents have a detrimental
effect on MPF process. effect on MPF process.
It is not possible to apply high pressures in an It is not possible to apply high pressures in an
arbitrarily chosen area while applying a low arbitrarily chosen area while applying a low
pressure in a closely adjacent area. pressure in a closely adjacent area.
APPLICATIONS OF MPF :APPLICATIONS OF MPF :
The magnetic pulse forming process has been primarily applied in the The magnetic pulse forming process has been primarily applied in the
forming of excellent conductors, such as aluminum, copper, brass and forming of excellent conductors, such as aluminum, copper, brass and
low carbon steel. It has also been used effectively to form poor low carbon steel. It has also been used effectively to form poor
conductors such as stainless steel for use with highly conductive sheaths. conductors such as stainless steel for use with highly conductive sheaths.
MPF is used widely to expand, compress or form tubular shapes and MPF is used widely to expand, compress or form tubular shapes and
has also been used effectively to form conical, ellipsoidal and flat work has also been used effectively to form conical, ellipsoidal and flat work
pieces and assembly operations in a single step. The method is also used pieces and assembly operations in a single step. The method is also used
for piercing, shearing, embossing, cupping, sizing, banding etc. for piercing, shearing, embossing, cupping, sizing, banding etc.
Tubular members can be joined to end fittings by magnetic swaging. Tubular members can be joined to end fittings by magnetic swaging.
PNEUMATIC PNEUMATIC MECHANICAL MECHANICAL
HIGH VELOCITY HIGH VELOCITY FORGINGFORGING
Just as a turret lathe can be set up to machine hundreds of Just as a turret lathe can be set up to machine hundreds of
identical parts, so also pneumatic mechanical, high velocity identical parts, so also pneumatic mechanical, high velocity
forging machine can be set up to produce hundreds of forging machine can be set up to produce hundreds of
identical forging without depending on the skill of the identical forging without depending on the skill of the
operator. operator.
High velocity forging is a closed die hot or cold forging High velocity forging is a closed die hot or cold forging
process which unlike conventional forging, deforms work process which unlike conventional forging, deforms work
metal at unusually high velocities. Identify, the final metal at unusually high velocities. Identify, the final
configurations of the forging is developed in one blow, or at configurations of the forging is developed in one blow, or at
most, in a few blows. most, in a few blows.
High velocity forging can be used for hot forging of the parts High velocity forging can be used for hot forging of the parts
of the same general shapes as those produced in of the same general shapes as those produced in
conventional forging hammers and presses. conventional forging hammers and presses.
COMPARASION WITH COMPARASION WITH CONVENTIONAL FORGINGCONVENTIONAL FORGING
The forces developed in high velocity forging are many The forces developed in high velocity forging are many
times more powerful and are sufficient to shape hard to times more powerful and are sufficient to shape hard to
work materials. work materials.
High velocity forging, single blow, hammers require less High velocity forging, single blow, hammers require less
moving weight than do conventional hammer to achieve moving weight than do conventional hammer to achieve
the same impact energy per blow.the same impact energy per blow.
This machine also requires considerably less space than This machine also requires considerably less space than
the conventional forging press. the conventional forging press.
COMPARASION WITH COMPARASION WITH CONVENTIONAL FORGINGCONVENTIONAL FORGING
Pneumatic-mechanical forging machines Pneumatic-mechanical forging machines
use:use:
the energy stored in a compressed gas the energy stored in a compressed gas
e.g. nitrogen e.g. nitrogen
the energy released from burning fuel the energy released from burning fuel
(petrol) oxidizer mixture to accelerate a (petrol) oxidizer mixture to accelerate a
ram to a high velocity for accomplishing ram to a high velocity for accomplishing
a deformation stroke or hammer.a deformation stroke or hammer.
PRINCIPLE OF OPERATION:PRINCIPLE OF OPERATION:
In the gas operated pneumatic mechanical machines, energy in obtained by expandingIn the gas operated pneumatic mechanical machines, energy in obtained by expanding
A High pressure gas to drive a piston down a cylinder. In most machines, theA High pressure gas to drive a piston down a cylinder. In most machines, the
pressurized gas is stored and made to act on the top of the ram with the help of quickpressurized gas is stored and made to act on the top of the ram with the help of quick
release mechanism for rapid acceleration of the ram. The gas accelerates the ram torelease mechanism for rapid acceleration of the ram. The gas accelerates the ram to
high speeds. During the process there is a very rapid build up on the work piece.high speeds. During the process there is a very rapid build up on the work piece.
Subsequent to each hammer blow the gas is recompressed. The original quantity ofSubsequent to each hammer blow the gas is recompressed. The original quantity of
gas is used time after time or no loss, resulting in very low operating cost. gas is used time after time or no loss, resulting in very low operating cost.
Repeatability is an important feature.Repeatability is an important feature.
PRINCIPLE OF OPERATION:PRINCIPLE OF OPERATION:
There is an inner frame and an outer frame within which the There is an inner frame and an outer frame within which the
inner frame is free to move vertically. As the trigger gas steel inner frame is free to move vertically. As the trigger gas steel
is opened, high pressure gas from the firing chamber acts from is opened, high pressure gas from the firing chamber acts from
the top face of the ram and forces the ram and the upper die the top face of the ram and forces the ram and the upper die
downward. downward.
Reaction to the downward Acceleration of the ram raises the Reaction to the downward Acceleration of the ram raises the
inner frame and lower die. The machine is made ready for the inner frame and lower die. The machine is made ready for the
next blow by means of hydraulic jacks that elevate the ram until next blow by means of hydraulic jacks that elevate the ram until
the trigger gas seal between the upper surface of the firing the trigger gas seal between the upper surface of the firing
chamber and the ram top is re established. chamber and the ram top is re established.
The machine uses air springs and thus the shock is not The machine uses air springs and thus the shock is not
transmitted to the floor. Therefore, a special foundation is not transmitted to the floor. Therefore, a special foundation is not
needed, and the ,machine can be placed directly on the factory needed, and the ,machine can be placed directly on the factory
floor. floor.
PRINCIPLE OF OPERATION:PRINCIPLE OF OPERATION:
ADVANTAGES OF PNEUMATIC-MECHANICAL FORGING :
• Metals difficult to forge by other methods can be forged successfully.
• Complex parts can be forged in one blow.
• Forging are made to size or within a minimum of machining allowance.
• Dimensional accuracy, surface details and often, surface finish are improved.
• Draft allowances can be reduced.
• Severe deformation results in greater gain refinement in some metals.
• Deep, thin sections can be forged.
DISADVANTAGES OF PNEUMATIC-MECHANICAL FORGING :
1. Process generally is limited to symmetrical parts.
2. Sharp corners and small radii can not be forged without causing
undue die wear.
3. The production rate is about the same as in hammer or hydraulic
press forging, but slower than in mechanical press forging.
4. Part size is limited to about 10 kg fore carbon steel forging, and to
lesser weights for forging made of stainless steel or heat resisting
alloys.
APPLICATIONS OF PNEUMATIC-MECHANICAL FORGING :
1. Symmetrical or concentric forging such as gears
and wheels.
2. Parts with thin webs and high rib height to width
ratios.
3. Forging of super alloys, refractory alloys, as cast
materials, low alloy steels, aluminum alloys,
titanium alloys, stainless steels etc.
4. Turbine blades and turbine wheels.
5. Valve bodies.
6. Rifle parts.
7. Missile components.
8. Housings for electronic devices.
9. Engine housings.
10.Rocket nozzle inserts, etc.
ECONOMIC CHARACTERISTICS
When making a cost comparison to aid in
selecting in between one of these special
processes and a conventional one, or when
choosing between two different special
processes, each of which appears capable of
accomplishing the necessary forming, the
engineer is advised therefore, to contact
manufacturers of the respective equipment to
obtain the most current information available.
ECONOMIC CHARACTERISTICSExperience indicates that the HVF processes are
generally more useful in the production of
smaller quantities of parts. For the production of
small number of parts, the unit cost makes a
HVF operation more favorable because of the
generally lower initial cost of tooling, capital
equipment etc. However as the number of parts
is increased and the unit cost for the
conventional method becomes the lower .In
industries that produce extremely large numbers
of parts, such as the stamping industry, are not
economically feasible for most HVF techniques.
CAPABILITY OF HVF PROCRSSESCharacteristics Characteristics Electro hydraulic Forming
High Explosive(stand-off)Bridge wire Spark discharge
Metal working operations
Tube bulging, drawing sizing, flanging, coining , blanking, stretching
Tube bulging, sizing, flanging, expanding, coining , blanking, stretching, embossing
Draw forming, sizing, flanging, expanding, coining ,blanking,stretching,embossing,beading,joining
Size limitations 6.1542mm diameter or larger
6.1542mm diameter or larger Limited only by available blank size
Shape complexity
Complex surface and shapes, especially tubular
Complex surface and shapes, especially tubular
Small and intricate, large and simple
Capital investment
Moderate Moderate low
Tooling cost low low low
Labor cost moderate moderate moderate
Production rate 360 parts per hr depending on part and equipment
360 parts per hr depending on part and equipment
0.5-4 parts per hr or less depending on part and facility
CAPABILITY OF HVF PROCRSSESCharacteristics Characteristics Electro hydraulic Forming High
Explosive(stand-off)Bridge wire Spark discharge
Cycle time Long medium medium
Energy costs low low high
Safety considerations Equipment interlocks, high voltage safety practices, trained personnel
Equipment interlocks, high voltage safety practices, trained personnel
Trained personnel
Method of energy release
Vaporization of wires Vaporization of medium Chemical detonation
Pressure wave velocity
20,000(6096)
20,000 (6096)
4,000 to 25,000(1219-7620)
Pressure wave duration
microseconds microseconds microseconds
Energy range(KJ) 20,000 to 175,000(27 to 237)
10,000 to 110,000(13.5 to 150 )
100,000 to 2,000.000(136-2712) per lb of explosive, up to 100 lb 45 kg detonator
Work-piece deformation velocity(m/s)
50 to 700 (15-213)
50 to 700 (15-213)
60 to 400 (18 to 122)
Energy transfer medium
Water or other suitable liquid Water or other suitable liquid Water, elastomers sand, molten salts
Characteristics Characteristics High Explosive(direct contact)
Electromagnetic Mechanical-Pneumatic forging
Metal working operations
draw forming, sizing, flanging, expanding, coining , blanking, stretch forming,embossing,beading, cutting, powder compacting, joining,
Hardening,welding, perforating, cladding, powder compacting
Hot, warm, cold forming water compacting, powder forging, cropping, blanking, piercing, coining
Size limitations Part size not limiting 0.1-72(2.5-1830mm) diam. and larger in some operations
Up to 24 (610mm) diam. larger on future machines
Shape complexity Simple shapes Compound surfaces, corrective forming on large complex shapes
Complex shapes thin forged sections
Capital investment low Moderate to high moderate
Tooling cost None to low High if work coil is regarded as part of tooling
moderate
Labor cost moderate Moderate to low moderate
Production rate 0.5-4 parts per hr or less depending on part and facility
Up to 12,000 parts per hr for simple parts and automated transfer equipment
60 to 100 parts per hr with automatic equipment, depending upon part complexity
CAPABILITY OF HVF PROCRSSES
ECONOMIC CHARACTERISTICSCharacteristics Characteristics High Explosive(direct
contact)Electromagnetic Mechanical-
Pneumatic forging
Cycle time medium Medium to short long
Energy costs high low moderate
Safety considerations
Trained personnel Equipment interlocks, high voltage safety practices, trained personnel
Guards and shields, trained personnel
Method of energy release
Chemical detonation Expanding magnetic fieldExpanding magnetic field Quick-release valveQuick-release valve
Pressure wave velocity
4,000 to 25,000(1219-7620)
Not applicableNot applicable Not applicableNot applicable
Pressure wave duration
Microseconds Microseconds Microseconds Microseconds Microseconds
Energy range(KJ) 0.5-8 psf high explosive 0-175,00(0-237)0-175,00(0-237) Up to Up to 400,000(542)400,000(542)
Work-piece deformation velocity(m/s)
Not applicable 50-1000(15-305)50-1000(15-305) 50-700(15-213)50-700(15-213)
Energy transfer medium
Direct contact or buffer material
Magnetic field (to be Magnetic field (to be operated in vacuum)operated in vacuum)
High – velocity High – velocity ramram
REFERENCES :REFERENCES :““Production Technology” by O.P.Khanna, Dhanpat Rai Publishers,1998.Production Technology” by O.P.Khanna, Dhanpat Rai Publishers,1998.
Materials and Processes in Manufacturing” by DeGarmo, Black & Kosher, Prentice-Materials and Processes in Manufacturing” by DeGarmo, Black & Kosher, Prentice-
Hall Publishers, 1997Hall Publishers, 1997
archive.metalformingmagazine.com/1997/01/7mfjan5.htm archive.metalformingmagazine.com/1997/01/7mfjan5.htm
www.metalwebnews.com/howto/explosive-forming/explosive-forming.html www.metalwebnews.com/howto/explosive-forming/explosive-forming.html
en.wikipedia.org/wiki/Electromagnetic_formingen.wikipedia.org/wiki/Electromagnetic_forming
www.fsb.hr/deformiranje/Presentation_Wentzel_TNO_PML_Rijswijk.pdf
web.mit.edu/3.082/www/team1_s03/presentation4.10.ppt web.mit.edu/3.082/www/team1_s03/presentation4.10.ppt
www.engineershandbook.com/MfgMethods/ehforming.htm www.engineershandbook.com/MfgMethods/ehforming.htm
en.wikipedia.org/wiki/Electromagnetic_forming en.wikipedia.org/wiki/Electromagnetic_forming
www.iap.com/metalfor.html www.iap.com/metalfor.html
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