deep drying

TOPICS• Deep drawing

• Super-plastic forming

• Explosive forming

• Equipments for sheet metal forming

DEEP DRAWING

HISTORY• Deep drawing is

one of the most important and widely used metal forming

• This process first developed in the 1700s consequently has been studied extensively until has become an important metalworking process.

DEFINITION

• “Deep drawing is the manufacturing process of forming sheet metal stock called blanks, into geometrical shapes.”

• Common shapes for deep drawn products include cylinders for aluminium cans and cups for baking pans. Irregular items, such as enclosure covers for truck oil filters and fire extinguishers, are also commonly manufactured by the deep drawing method.

MECHANICS OF DRAWING• A blank diameter D is drawn into die

by means of a punch of diameter .The punch and die have radii R. The sides of punch and die separated by clearance. Which is about 10% greater than the sheet thickness. The punch applies a downward force F to deform the material. While the downward holding force is applied by blank holder.

PROCESS• A round blank is first cut from flat

stock .The blank is placed in the draw die, when pushes the blank through the die on the return stroke the cup is stripped from the punch by the counter-bore in the die .The tope edge of the shell expands slightly in order to make this possible . Note that the amount of spring-back in the drawing has been exaggerated. The punch has an air vent to prevent a vacuum from being formed when the part is stripped from the punch.

METAL FLOW DURING DRAWING

• To understand what happens to metal during a drawing operation, the process should be broken into progressive stages of formation. Here a flat circular blank is drawn into a flat bottomed cup by forcing a punch against the blank.

• During the first stage of process the punch contact the blanks .This section forms the flat bottom of the cup and is not distorted by the punch.

Cont...• Upon further

penetration of the punch the metal is bent or wrapped around the punch nose and die radius.

• As the punch penetrate still further, the metal that was previously bent over the disc radius becomes straightened. Additional metal is pulled over the die radius, which in time straightened as the punch progress downward .In other words, the outside edge of the blank is being drawn towards the punch.

Cont..• In order to accomplish this successfully

the section of the blank must reduce in circumference and the only way to do this is for the metal to compress and become thicker.

• The force created by the blank holder also increase frictional force. Too much blank-holder pressure may tear the sidewall of the drawn cup. The sidewall transmits the punch force to the area of draw on the die radius. Tearing will generally occur near the punch radius because this area will thin due to tension force.

TOOL MATERIAL• Punches and dies are typically made

of tool steel, however carbon steel is cheaper, but not as hard and is therefore used in less severe applications, it is also common to see cemented carbides used where high wear and abrasive resistance is present. Alloy steels are normally used for the ejector system to kick the part out and in durable and heat resistant blank holders.

LUBRICATION AND COOLING• Lubricants are used to reduce friction

between the working material and the punch and die. They also used for removing the part from the punch. Some examples of lubricants used in drawing operations are heavy-duty emulsions, phosphates, white lead, and wax films. Plastic films covering both sides of the part while used with a lubricant will leave the part with a fine surface.

DEFECTS1. Wrinkles - caused due

to excessive clearance between the punch and die. Also caused due to improper pressure pad pressure and die and punch radii.

2. Ruptures - caused by incorrect draw ratio another reason is improper die and punch radii.

• 3. Excess thinning- of the cup wall - caused by incorrect die and punch clearance and radii and also excessive pressure by pressure pad.

ADVATAGES• Tool construction costs are lower in

comparison to similar manufacturing processes.

• The technique is ideal for products that require significant strength and minimal weight.

• The process is also recommended for product geometries that are unachievable through other manufacturing techniques.

• Deep drawing is especially beneficial when producing high volumes, since unit cost decreases considerably as unit count increases

DISADVANTAGES• Material thickness has a large effect

on processing price.

• Special sleeves required to assist in driving the parts into the dies.

• This process is costly for low production rate.

COMPARISONDEEP DRAWING• Deep drawing is the

manufacturing process of forming sheet metal stock, called blanks, into geometrical shapes.

• Only used for limited die design.

• It can be suffer from spring back.

• No Preheating required, process done at room temp.

SUPERPLASTIC FORMING• Super plastic forming is used

to elongate the material beyond 100% of it length.

• It can also be only used for limited die design.

• It does not suffer from spring back.

• Preheating required before the super-plastic forming.

Cont...• Suitable for

mass production.

• Low production cost.

• Several steps are required for deep drawing.

• Low labour cost.

• Also suitable for mass production.

• High production cost.

• It is also a one step process.

• Low labour cost.

APPLICATIONS IN PAKISTAN INDUSTRY

1. PAKISTAN ENGINEERING CO. LTD (LAHORE)

CONCRETE MIXERS; STORAGE TANKS FOR OILS

2. SINGER PAKISTAN LTD (KARACHI)

WASHING MACHINE ; GAS APPLIANCES; REFRIGERATOR; DEEP FREEZER

3. LIBRA ENGINEERING (KARACHI.)

DEEP DRAWN COMPONENTS, SHEET METAL COMPONENTS.

4.HMA STAINLESS STEEL PUMPS MANUFACTURERS (PVT) LTD (KARACHI)

CENTRIFUGAL PUMPS (HORIZONTAL/VERTICAL), DEEPWELL TURBINES

SUPER-PLASTIC FORMING

HISTORY• Super plasticity, first observed some seventy

years ago, remained a scientific curiosity until about twenty years ago.

• Since the early 1970’s, super plastic forming of titanium alloys became a feasible manufacturing technology for military aircraft in USA and also for the Concorde supersonic civil aircraft in Europe.

• In the next decade, new super plastic titanium and aluminum alloys were developed for different structural applications for military airframes and engines

DEFINITION • Super-plastic forming is a

metalworking process for forming

sheet metal. It works upon the

theory of super-plasticity, which

means that a material can elongate

beyond 100% of its original size.

Process • The process begins by

placing the sheet to be formed in an appropriate SPF die, which can have a simple to complex geometry, representative of the final part to be produced. The sheet and tooling are heated and then a gas pressure is applied, which plastically deforms the sheet into the shape of the die cavity.

Cont…• To begin with, the material

must have an ultra-fine grain size. It is then heated up to promote super-plasticity. For titanium this is around 900 °C (1,650 °F) and for aluminium it is between 450–520 °C. In this state the material is not very strong so processes that are usually used on plastics can be applied, such as: thermoforming, blow forming, and vacuum forming; it may also be deep drawn.

1.lower water cooling plate2. inner heater3. die,4. outer heater5. aluminum sheet blank6. upper heater7. upper water cooling plate

MATERIALS USED FOR SUPER-PLASTIC FORMING• Aluminum alloys

• Titanium alloys

• Bismuth-tin alloys

• Zinc-aluminum alloys

• Stainless steel

• Aluminum-lithium alloys

PROCESS OPTIMIZATION AND DIE DESIGN

• As the first step of processing design, a geometric design of the die surface geometry has been designed.

• In order to estimate rationality of the designed surface geometry, a numerical simulation of super-plastic air bulging of the front fender is carried out.

• The die is heated mainly by both inner heater and outer heater. The blank is heated by upper heater.

• Both water cooling plates are fixed for press protection and an asbestos plate is fixed between the water cooling plate and upper heater.

DIE AFTER MACHINING

DEFECTS

1-Cracks can be produced when a material is elongated beyond a safe limit.

Crack Defect

BURNT DEFECT

2-As this process takes place at a very high temperature so another defect that can take place is that the material can burn during this process.

ADVANTAGES • The major advantage of this process is

that it can form large and complex work pieces in one operation.

• The finished product has excellent precision and a fine surface finish.

• Lower strength required and less tooling costs.

• Elimination of unnecessary joints and rivets.

• It minimizes the amount of scrap produced.

• It is a one step process.

• Higher material elongations.

• Reduction of subsequent machining.

• It does not suffer from spring back.

DISADVANTAGES • The biggest disadvantage is its slow forming

rate.

• Cycle times vary from two minutes to two

hours.

• It is usually used on lower volume products.

• Also materials must not be super-plastic at

service temperatures.

COMPARISONSuper-plastic forming• this process is that it

can form large and complex work pieces in one operation.

• It is slow forming process.

• Low tooling cost.

• It has good surface finish.

Roll forming• long parts with

constant complex cross-sections are produced.

• high production rates;

• high tooling costs.

• It has also good surface finish.

COMPARISONSuper-plastic forming

• this process can form large and complex work pieces in one operation.

• Low production rate.

• Low tooling and equipment costs.

Deep drawing

• deep parts with relatively simple shapes are produced.

• High production rate.

• High tooling and equipment costs.

APPLICATIONS 1.Honda Atlas cars Limited,

SUZUKI, TOYOTA.

Automotive Door panels or windows etc.

2.KAMRA Pakistan .

3. Pakistan Aeronautical complex.

Aircraft Frames and Skins.

Cont...• Pakistan Railways Lahore.

Complex shape parts: window frames, seat structures, ventilation ducts, underground front face.

EXPLOSIVE FORMING

HISTORY • Explosive forming was applied in the 1960’s in

the USA and the USSR for aerospace and space applications. But in the 1980’s applications were hard to find due to the development of other metal forming technologies that can be applied in a workshop jointly with other processes without the safety measures that come with applying explosives. Also, the technology of explosive welding was developed in the 1970’s. Companies that operated explosive forming focused to explosive welding large plates of e.g. titanium or aluminium to steel.

Cont…• Several factors contributed to the re-

introduction of explosive forming in the 1990’s.Products with more complicated shapes were required in smaller quantities. The time-to market decreased and companies became used to subcontract specialized work. TNO started a research program in 1995 that resulted in the spin-off company Exploform B.V. in 1998 in order to make explosive forming commercially available. Exploform has a unique variety of formed products.

DEFINITION• Explosive forming is a metalworking

technique in which an explosive charge is used instead of a punch or press. (The parts are formed at a rapid rate, and thus these processes are also called high velocity forming processes).

PROCESS• Explosive forming is the

technology of forming of a metal sheet or tube by an explosion.

• A metal sheet is placed in a die.

• The die cavity is vacuumed.

• The explosive charge is put above the sheet under water.

• The explosives are detonated.

• The explosion forces the sheet into the desired shape at a high speed.

Cont…• The explosive charge can be adapted for any

product size and sheet thickness. The forming technology makes it possible to successfully form both 0.2 mm aluminium and 13 mm nickel. Products of 10 meters length have been formed at the production site. Any metal can be explosively formed, for example, various nickel, aluminium, titanium and iron alloys.

• The configuration of the explosive charge can be optimised for any product shape. For example for cylinders, flanges, textured panels, vessel heads, dishes and many other shapes.

EXPLOSIVELY FORMED METAL

SHEET

Detonation

TRANSMISSION MEDIUM• Energy released by the explosive is

transmitted through medium like air, water, oil, liquid salts. Water is one of the best media for explosive forming since it is available readily, inexpensive and produces excellent results. The transmission medium is important regarding pressure magnitude at the work piece. Water is more desirable medium than air for producing high peak pressures to the work piece.

TYPES OF EXPLOSIVE FORMING

• Explosive Forming Operations can be divided into two groups, depending on the position of the explosive charge relative to the workpiece.

• Standoff Method

• Contact Method

STANDOFF METHOD• In this method, the explosive charge

is located at some predetermined distance from the workpiece and the energy is transmitted through an intervening medium like air, oil, or water. Peak pressure at the workpiece may range from a few thousand psi (pounds/inch2) to several hundred thousand psi depending on the parameters of the operation.

• The system used for Standoff operation consists of following parts

• An explosive charge

• An energy transmitted medium

• A die assembly

• The workpiece.

• Above figure shows an arrangement of standoff explosive forming operation. The die assembly is put together on the 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. The explosive charge is placed in position over the centre of the work piece . The explosive charge is suspended over the blank at a predetermined distance. The complete assembly is immersed in a tank of water

• After the detonation of explosive, a pressure pulse of high intensity is produced. A gas bubble is also produced which expands spherically and then collapses until it vents at the surface of the water. When the pressure pulse impinges against the work piece, the metal is displaced into the die cavity.

Contact Method• The explosive charge in the

form of cartridge is held in direct contact with the work piece while the detonation is initiated. The detonation builds up extremely high pressures (up to 30,000MPa) on the surface of the work piece resulting in metal deformation, and possible fracture. The process is used often for bulging tubes, as shown in Fig.

ADVANTAGES• Maintains precise tolerances.

• Eliminates costly welds.

• Controls smoothness of contours.

• Reduces tooling costs.

• Less expensive alternative to super-plastic forming.

• The explosive charge can be adapted for any product size and sheet thickness.

• Any product size, shape and sheet thickness is possible.

• Die costs are relatively low since only a lower die part is needed.

• Low-cost die concepts reduce initial costs further, for example concrete dies cast on machined polystyrene.

DISADVANTAGES• Required long setup time producing

one product at a time.

• It is unavoidably a batch process.

• Suitable for low-quantity production.

• The limitation of these processes is the need for skilled personnel.

COMPARISONExplosive forming • In Explosive forming

an explosive charge is used instead of a punch or press.

• It can be use for large size of metal sheets.

• It can suffer from spring back.

• No preheating required before the explosive forming.

Super plastic forming• In super plastic

forming punch or press is used to form metal sheet forming.

• It can be only used for limited die design.

• It does not suffer from spring back.

• Preheating required before the super-plastic forming.

• Suitable for low-quantity production.

• Less production cost.

• Any product size, shape and sheet thickness is possible.

• It is a one step process.

• High labour cost.

• Suitable for mass production.

• High production cost.

• It can be used for definite shape, size and sheet thickness .

• It is also a one step process.

• Low labour cost.

APPLICATIONS IN WORLD

• SOURIAU Pa&E COMPANY

Washington-98801, USA

• Pa&E company is hole sale dealer and produce different products such as.

Boiler Products

OTHER EXAMPLES OF EXPLOSION FORMED by

SOURIAU Pa&E

Missile Components Aircraft Radar Shields

EXPLOSIVELY FORMED CONES

Space Shuttle Skin Before and After Explosive Forming

Rocket EngineNozzles

TURBINE ENGINE COMPONENTS

Finished Parts

Tubes Explosive Forming Die

ISOGRID PRODUCT FAMILY

Complex ductsDouble curved products•From flat milled sheet metal.Proof of principle grid on inside & on outside.

aded panelBeBeaded panel

DETONOGRAPHY • An artistic method to duplicate

natural material

EXPLOSIVE ENGRAVING OF COINS IN AL-PLATE:

• Set-up of the coins on the plate.

Explosive engraving of coins in Al-plate

DETAILS OF COIN ENGRAVING

EXPLOSIVELY FORMED HULL OF AN OCEAN VIEWER VESSEL

• In Australia, the Department of Mechanical Engineering at the University of Adelaide . who produced boat hulls by making a concrete "swimming pool" into which sheet-metal was placed, and when water filled and explosively fired, produced a complete hull-form.

The starboard side of the bow section prior to explosive forming

Detonation of the explosive for high energy rate forming of the bow section

Explosively formed bow section of the ocean viewer vessel at RFI in Cairns

EXPLOSIVELY FORMED SHIP 'THE BOSS' BY RFI IN

AUSTRALIA :

EQUIPMENTS FOR SHEET MRTAL FORMING

Why Do We Need Metal Forming Tools?

Metal forming tools are important for any project that involves metal. You certainly can't bend or form a heavy duty steel plate to tight requirements by hand; you need a machine that is powered by more than just elbow grease. Common business that need metal shaping tools include car production plants, airplane manufacturers, and small businesses that deal in iron works and metal fencing.

TYPES• Wheeling Machine

• Air power hammer

• Shrinker stretcher

• Bead forming Machine

• Tube Forming Machine

• Forming Dies

WHEELING MACHINE• The Wheeling Machine, also called an

English Wheel, is a popular type of metal forming tool that is used to create double curves in metal. The user puts a flat metal sheet (usually aluminium or mild steel) through this C-shaped machine to get even curves. These machines are usually used for the curving elements of cars, boats, and other complicated machinery. The Wheeling Machine stretches and thins the metal before forming it into the desired shape.

AIR POWER HAMMER

• An air power hammer is a tool that has replaced the need to use a handheld hammer for blacksmithing projects. This metal forming tool uses a powerful force to bend even the toughest metals into desired shapes. This tool shapes and planishes metal. Shaping is done by modifying the condition of the metal (such as stretching it out first) and then turning it into another form. When something is "planished" it is being reshaped from light hammer force.

SHRINKER STRETCHER• Another metal forming tool is the

Shrinker Stretcher tool. These machines are built to stretch or shrink various types of metal, usually mild steel. A special adapter, called a "jaw" is required for this type of machine. The Shrinker Stretcher is air-powered and easily switched from a shrinking setting to a stretching setting with a simple change of the jaw.

BEAD FORMING MACHINE

• Uniform beads are small circular pieces of metal that have been smoothed around the edges. Metal beads could be used for jewellery or as components in major machinery; think of an assembly line that requires constant movement on wheels. The beads are formed when the two interlocking pieces slide against each other continuously.

TUBE FORMING MACHINE

• Tube forming machines refer to various types of equipment that are used in order to form tubing, which is the process of altering tubing into complex shapes. A tube is defined as a long and thin hollow cylinder that is most commonly used to either convey a fluid or gas, or to function as a passage. The machines that perform tube forming processes must be able to maintain a high level of accuracy due to the complexity of the various shapes required. As a result, tube forming machines are generally either dedicated machines or automated manufacturing cells. Some examples of applications and industries that utilize tube forming machinery include: marine, for use in exhaust products, heat exchangers, piping systems and more; automotive, for applications such as various automation equipment and tubing assemblies; and medical, for use in complex components such as glass capillary tubes, epidural needles and arthroscopic drivers

Drum Making Machine• Horizontal drum making machine is complete

line machine includes cutting, welding, forming, seaming, steel drum body production line and painting line. The middle step includes flanging machine, corrugating machine, beading machine, seaming machine, leakage testing machine, punch pressing machine, point welding machine and seaming welding machine. The whole equipment is automatic, controlled by programming controller. The feeding and transporting devices are driven by hydraulic system

TYPES OFFORMING DIES

• Solid form Dies

• Pad-type Dies

• Curling Dies

• Embossing Dies

• Coining Dies

• Bulging Dies

• Assembly Dies

FORMING DIES• It is sometimes difficult to

distinguish between a bending and forming dies . a forming operation is generally along curved axes rather than a straight axes.

• Forming operations may strengthened the work piece and add rigidity.

• The particular type of forming operations are classified in group

SOLID FORM DIES• Solid form dies generally

consist of a male and female die shaped to contour of work piece. Allowance for clearance equal to the thickness of the work piece is provided between the male and female die .This type of tooling is generally used for forming operation in progressive dies .

CURLING DIES• A curling die rolls a raw

edge of sheet metal into a roll or curl .The purpose is to strengthen the raw edge provide a protective edge and improve the appearance of the product .The sheet metal to be curled must be soften enough to roll properly .A lubricant should be used during curling operation.

EMBOSSING DIES• Embossing is a shallow

forming operation in which the work piece material is stretched over a male die and caused to conform to the male die surface by a mating female die surface . the finished product will have a depressed details on it and raised detail on others.

BULGING DIES• Bulging is an internal

forming operation used to expand portion of a drawn shell or tube. The forming force is applied from inside the work piece and is transmitted through a medium that will flow and not compress. The more common media are rubber urethane heavy grease oil or water. Rubber and urethane are preferred as a pressure dispersing medium because they are clean and easy to use.

ASSEMBLY DIES• In this type of dies are used

for assembling two or more parts held in position and then locked in position by riveting staking crimping or press fitting. The operator may be physically place the parts in position in die. A large quantity of parts may justify a more complicated die that would automatically assemble the parts in the die while being from a hoper.

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