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JASPREET SINGH (10406EN013)

TEJ PRAKASH (10406EN014)

SAHIL DEV (10406EN016)

RAHUL WALTER (10406EN017)

DESIGN AND DEVELOPMENT OF STRETCH FORMING SETUP

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WHAT IS FORMING?

Metal reshaping process

Uses mechanical deformation

No material removal

3CHARACTERISTICS OF FORMING PROCESS

Very high required loads and stresses

Large, heavy and expensive machinery

Used in mass production

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FORMING PROCESSES

Classified by differences in effective stresses

Compressive forming

Tensile forming

Combined compressive and tensile forming

Bending

Shearing

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COMPRESSIVE FORMING

Uniaxial or multiaxial compressive loading

Rolling

Extrusion

Die forming

Forging

Indenting

6TENSILE FORMING

Uniaxial or multiaxial tensile stress

Stretching

Expanding

Recessing

7COMBINED TENSILE AND COMPRESSIVE FORMING

Extrusion

Deep drawing

Spinning

Flange forming

Upset bulging

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BENDING AND SHEARING

Plastic deformation by bending / shearing load

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STRETCH FORMING

Forming by combined tensile and bending forces

Two types:

Simple stretch forming

Tangential stretch forming

For fabrication of contours having U-forms

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SIMPLE STRETCH FORMING

Fixed jaws

Minimum deformation under the die

Sheet expand

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TANGENTIAL STRETCH FORMING

Movable jaws

Plastic pre strain

Two steps:

Gripping by jaws

Forming by die

12VIDEO : TANGENTIAL STRETCH FORMING

13STRETCH FORMING EQUIPMENT IN INDIA

Two types:

Longitudinal

Transverse

Can be integrated to CNC

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GRIPPING MECHANISM

Two types:

Integral

Discrete

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PROJECT DESIGN

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BILL OF MATERIALS

Component × Quantity Material Mechanical Properties

1. Sheet ×1 AL-5052 UTS = 227.57 Mpa YS = 193.05MPa

2. Main Bolt × 1 C60(Carbon Steel) UTS = 736 Mpa YS = 412 MPa

3. Rotating Holder×1 C60(Carbon Steel) UTS = 736 Mpa YS = 412 MPa

4. Supporting Rod ×1 C60(Carbon Steel) UTS = 736 Mpa YS = 412 MPa

5. U-Frame ×1 C60(Carbon Steel) UTS = 736MPa YS = 412MPa

6. Stopper × 2 A-36 Mild Steel UTS = 399.8 Mpa YS = 250.2 MPa

7. Mini Bolt × 2 A-36 Mild Steel UTS = 399.8 Mpa YS = 250.2 MPa

8. Base ×1 A-36 Mild Steel UTS = 399.8 Mpa YS = 250.2 MPa

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STRESS REQUIRED FOR FORMING

AL-5052(400mm x 200mm x 1mm)

= 210.27 MPa

Force = = 50.46 KN

Good man criteria for failure is and

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NOTATIONS USED

is mean tensile and shear stress

is yield tensile and shear stress

is stress concentration factor

is average tensile and shear stress

is ultimate tensile and shear stress

is factor of safety

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DESIGN OF BOLT

ISO Metric thread

  so area obtained is 348.65mm2

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CONTINUED…

From standard machine design handbook we get

Major diameter of bolt = 22mm

Minor diameter of bolt = 20.7mm

Lead angle = 0

Pitch = 1mm

Length of threaded portion is found by Goodman Yield Criteria of shear stress :

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CONTINUED…

=

N = 43, so threaded portion length = 43mm but we take it as 60mm and an extra unthreaded portion of 30mm to move in U-frame

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DESIGN OF BASE

Let b = t for ease of analysis

b=26mm

And t=26mm

for ease of manufacturing let b=30mm and t=26mm

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DESING OF ROTATING HOLDER

Using Goodman criteria we get

 

t=3mm now for the ease of manufacturing let t= 5mm

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CONTINUED…

for internal threading

Minor diameter = 20.9mm

Major diameter = 22.9mm

Hole in the rotatory holder has radius = 20.5mm and distance between the center of two semi circular arcs is 12mm

Area that withstands tensile failure is 40×t1×2×10-3 mm2

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CONTINUED…

We get =4.3mm but for manufacturing purpose we take it as 5.5mm.

The arm length of the rotary frame is taken from kinematic consideration that frame should have a free rotation about rod even at maximum stretching so length L=(57.5+12+20.5+76)mm

L=166mm

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DESIGN OF SUPPORTING ROD

Max shear force = load/2

We get D=21mm

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CONTINUED…

maximum bending moment is at distance of 70mm from one end

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CONTINUED…

Using Goodman criteria

We get D=40mm

So final Dimensions of D is 40mm.

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DESIGN OF U-FRAME

Here the failure will be due to shearing through the holes

Using Goodman criteria for shear

During shear area of resistance will be = thickness of frame (t) × perimeter of bolt head

Perimeter of bolt head is 44×10-3mm.

 

We get t=5.28mm

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CONTINUED…

Now we find the thickness according to the bending moment of the bolt

From space constraints width of the bar is 80mm

Factor of safety = 1.5

M=50.45×103×50×10-3

y=t/2

I=bt3/12

(50.45×103×50×10-3×Y)/(bt3/12)

Using Goodman criteria 

we get t=25.6mm=26mm, so the final value of t=26mm.

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WORKING OF VICE

Five main components

Sheet is fixed

Bolt is rotated

U-frame can rotate about the rod

Always tangential force on the sheet

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PLANS FOR 8TH SEMESTER

The next step involves designing a die for this specification of sheet so that is does not get torn.

Fabrication of the components of vice.

Fabrication of die.

Testing of the setup.

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REFERENCES

Design data hand book by K.Mahadevan and K.Balveer Reddy.

Manufacturing technology by Kalpakjian.

En.wikipedia.org/wiki/sheet_metal.

Literature by training in aluminum application technology(TALAT).

www.sciencedirect.com/science/article/pii/S1003632609602570