group (17) wire drawing.pdf

8/13/2019 Group (17) Wire Drawing.pdf

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Group: 17

Under Supervision o

Dr. Mohamed A. Da

12/24/2013

WireDrawing Process


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INTRODUCTION

Drawing is a metalworking process which uses tensile forces to stretch

metal. It is broken up into two types: sheet metal drawing and wire, bar,

and tube drawing. The specific definition for sheet metal drawing is that

it involves plastic deformation over a curved axis. For wire, bar, and

tube drawing the starting stock is drawn through a die to reduce its

diameter and increase its length. Drawing is usually done at room

temperature, thus classified a cold working process, however it may be

performed at elevated temperatures to hot work large wires, rods or

hollow sections in order to reduce force.

Types of drawing processes:

Sheet metal

Deep drawing : as piercing, ironing, necking, rolling, and beading.

Bar, tube & wire

Bar, tube, and wire drawing all work upon the same principle: the

starting stock drawn through a die to reduce the diameter andincrease the length. Usually the die is mounted on a draw bench.

The end of the work piece is reduced or pointed to get the end

through the die. The end is then placed in grips and the rest of the

work piece is pulled through the die. Steels, copper alloys, and

aluminum alloys are common materials that are drawn.

Drawing can also be used to produce a cold formed shaped cross-

section. Cold drawn cross-sections are more precise and have a

better surface finish than hot extruded parts. Inexpensive materialscan be used instead of expensive alloys for strength requirements,

due to work hardening.


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Wire drawing:

Is a metal working process used to reduce the cross-section of a wire by

pulling the wire through a single, or series of, drawing dies. There are

many applications for wire drawing, including electrical wiring, cables,tension-loaded structural components, springs, paper clips, spokes for

wheels, and stringed musical instruments. Although similar in process,

drawing is different from extrusion, because in drawing the wire is

pulled, rather than pushed, through the die. Drawing is usually

performed at room temperature, thus classified as a cold

working process, but it may be performed at elevated temperatures for

large wires to reduce forces. More recently drawing has been used with

molten glass to produce high quality optical fibers.In wire drawing, differences are made according to the dimensions of

the wire between:

coarse drawing: d = 16 to 4.2 mm

medium drawing: d = 4.2 to 1.6 mm

fine drawing: d = 1.6 to 0.7 mm

ultra-fine drawing: d < 0.7 mm, and according to the machine used,

between:

single-draft drawing

tandem drawing.


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Products:

Wire and rod drawing ar

Wires and rods with smfields of application.

Figure 1: field

Permissible deformIn single drawing, the p

Steel wires =150

Cu materials = 200

e used to produce

oth surfaces and low tolerances for

s of application of drawn wires and rods

ations : rmissible deformations are around:

200 %

%

various


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Drawing force:

According to Siebel, the drawing force can be calculated with the

following equation.

The mean coefficient of friction is around = 0.035 (= 0.02 to 0.05).

The optimum drawing angle, requiring the least force, is around 2=

16o.From this it follows for the angle in radians:

If these values are brought into the above equation,

then the drawing force during wire drawing can be determined

approximately with the simplified equation and the deformation

efficiency = 0.6


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Die design:

The drawing die co These are the con

and approach angle

shaped back relief l

The length of the

The approach angl

the surface finish o

sists of three zones.-shaped intake with the entr

2, the bearing land l3 and t

4 with the back relief angle

ylindrical guide bush l3 is a

2influences the drawing

the wire.

angle 2

e cone-

.

ound:

orce and


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Die life and die wear:Two primary variables that control die life in any metal forming

operations are pressure and temperature

a) Pressure: pressure acting on the die in wiredrawing is much lower

than that found in other cold forming operations , such as cold

heading and backward extrusion

b) Temperature: temperature is often a far more critical factor in

controlling die life.

Although it would seem logical that wear would occur uniformly along

the approach zone, this is not the case in practice. Maximum wear(measured in volume loss) normally occurs at the point at which the wire

initially contacts the die. There, a deep annular crater is formed, which is

referred as a wear ring

Figure 2 : Wear Formed By Ringing In A Drawing Die

Ringing results when the plane of impingement of wire on the die

oscillates about a mean position because of irregularities of size and

vibration of the wire. As a consequence, a narrow zone of the die bore is

subjected to a cyclic load with eventual subcutaneous failure by fatigue.


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Once a wear ring develops, deformation may occur prior to the contact

point in the drawing die. This is called bulging and results from

backup or upsetting of near-surface regions of the wear as contact is

made at the wear ring location in the die. Bulging occurring at the initialof contact in the die throat limits lubricant entry into the die and

accelerates the die wear. Lesser amounts if wear occur along the contact

length of the approach zone, although here too wear is not uniform and

often results in an oval rather than a circular wear surface.


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Die material:

Industrial diamond:

Industrial diamond is the hardest material known. where hardness is

defined as resistance to scratching and is graded between 1 (softest) and

10 (hardest) using the Mohs scale of mineral hardness. Diamond has a

hardness of 10 (hardest) on this scale. The hardness of industrial

diamond depends on its purity, crystalline perfection and orientation:

hardness is higher for flawless, pure crystals oriented to

the [111] direction (along the longest diagonal of the cubic diamond

lattice). Nanocrystalline diamond produced through CVD diamond

growth can have a hardness ranging from 30% to 75% of that of single

crystal diamond, and the hardness can be controlled for specific

applications. Some synthetic single-crystal diamonds and HPHT

nanocrystalline diamonds (see hyperdiamond) are harder than any

known natural diamond.


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Tungsten carbide:

Tungsten carbide is approximately two times stiffer than steel, with

a Young's modulus of approximately 550 GPa

Sintered tungsten carbide cutting tools are very abrasion resistant and

can also withstand higher temperatures than standard high speed

steel tools. Carbide cutting surfaces are often used for

machining through materials such as carbon steel or stainless steel, as

well as in situations where other tools would wear away, such as high-

quantity production runs. Because carbide tools maintain a sharp cuttingedge better than other tools, they generally produce a better finish on

parts, and their temperature resistance allows faster machining. The

material is usually called cemented carbide, hard metal or tungsten-

carbide cobalt: it is a metal matrix composite where tungsten carbide

particles are the aggregate and metallic cobalt serves as the matrix.

Manufacturers use tungsten carbide as the main material in some high-

speed drill bits, as it can resist high temperatures and is extremely hard.


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Cemented carbide:

Cemented carbide, also called widia, is a hard material used in

machining tough materials such as carbon steel or stainless steel, as well

as in situations where other tools would wear away, such as high-

quantity production runs. Most of the time, carbide will leave a better

finish on the part, and allow faster machining. Carbide tools can also

withstand higher temperatures than standard high speed steel tools.


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Machines:

The high-production Dual Chain draw benches are designed to draw

tubing through dies and over internal

dies, as required to reduce diameter and wall as well as improve

finish

Bench draw machine

And yield strengths of the tubing.


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Dry Drawing Machine

Dry Drawing Machine for steel wire& rope industry

1.Dia. of Block: 200-1200mm

2.Block number: 2-12Nos

3.Inlet wire: 4~14mm

Straight Line Wire Drawing

Machine are suitable for the high &

low carbon steel wire below size of

14mm, with Siemens PLC & invertercontrol system to assure high speed

& stable operation.

Low Carbon steel wire product used

in mesh net, steel fiber, nail & staple

making, construction, agriculture & furniture field, etc. And other steel

wire product used in prestressing wire, PC wire, spring, steel rope wire,

steel cord & Bead wire for tyre

Figure 4: Electro galvanizing machine

Figure 3: wire copper plating machine


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ContentsINTRODUCTION.............................................................................................................................................2

Wire drawing:............................................................................................................................................3

Products: ...............................................................................................................................................4

Drawing force:..................................................................................................................................... 5

Die design: ....................................................................................................................................................6

Die life and die wear: ....................................................................................................................................7

Die material:..................................................................................................................................................9

Industrial diamond: ...............................................................................................................................9

Tungsten carbide:................................................................................................................................10

Cemented carbide: ..............................................................................................................................11

Machines: ....................................................................................................................................................12

group (17) wire drawing.pdf

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