design analysis of tools and process simulation for a sheet metal component

8/10/2019 Design analysis of tools and process simulation for a sheet metal component

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Design analysis of tools and process

simulation for a component with

multiple bends

REPORT

Submitted by

SUDHAKAR.K (2013214035)

Under the Guidance of

Dr. Latha Nagendran

Professor

College of Engineering Guindy

Anna University, Chennai

ANNA UNIVERSITY CHENNAI 600 025

(CEG Campus)

October 2014


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Introduction:

I offered a project of designing a multiple bend components in SVL ENTERPRISES- A vendor

of TI cycles. SVL is a medium scale Industry located in Thiruvallur.

Major works they are done

Bicycle stands for TI cycles

Bicycle carriers for TI cycles

Channels for TI metal forming

Crank case plating for Caterpillar.

Bicycle side stand component:

I take the process reduction of the bicycle side stand. The various component of the bicycle

side stand are

Bracket

Leg rod

Cup

Holder

bush

Springs

Washers

Rivets

Bracket:

Bracket is a component that connects the leg rod and bicycle wheel holder. The various

process of manufacturing of bracket are

1. Sheet strip cutting

2. Piercing, Notching and blanking

3. Company identity Marking tool

4. First forming

5. Second forming

6. Folding

7.

Acid cleaning

8. Powder coating


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PROCESS ILLUSTRATION


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Bracket material:

According to IS 1079: 2069Sheet material is selected

HR3 DD grade

Density =7850 kg / mm3

Tensile strength = 300 N / mm2 Percentage of elongation = 23%

Delivery condition is hot rolled Annealed Normalized and Descaled.

Min internal bend radius is of thickness

Composition:

C Mn P S Cr Si

0.08 0.40 0.035 0.030 0.05 0.030

Marking tool

Marking of company identity is done by the coining operation. Coining is a form of

precision stamping in which a work piece is subjected to a sufficiently high stress to induce plastic

flow on the surface of the material.

Force required to Identity marking

Coining force = Perimeter x Depth of impression x Tensile strength

Avg. perimeter = 120 mm (calculating by measuring the outside length of the letters)

Force = 120 x 0.5 x 300

= 18,000 N

Embossing:

Embossing is a process for producing raised or sunken designs or relief in sheet metal. This

process can be made by means of matched male and female roller dies, or by passing sheet or a

strip of metal between rolls of the desired pattern.

Force required to embossing

Embossing Force = Perimeter (P) x Average embossing depth (D) x Tensile strength (S)

During first forming:

For small embossing, Force = P x D x S

= 42 x 3 x 300

= 37,900 N


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For long embossing, Force = P x D x S

= 58 x 6 x 300

=104400 N

During second forming:For small embossing, Force = P x D x S

=38 x 2 x 300

= 22,800 N

For long embossing, Force = P x D x S

= 56 x 3 x 300

= 50400 N

Bending:

Sheet metal bending is the plastic deformation of the work over an axis, creating a change

in the part's geometry.

Force required to bending:

Force =

k = Bending factor = 1.33

s = ultimate tensile strength

l = length of bend part

t = thickness

w = die opening = 8t

Force =.33 X 2 X 300 X 2.5

X 2.5

= 5236.8 N

= 5237 N

Here three places the V- bending is happened. So, three times of the bending force was required.

Total force = 18000 + 37900 + 104400 + 22800 + 50400 +5237 x 3

= 249211 N

= 25 tons (approximately)


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Press selection

25 ton force is required to for the component. Considering the safety and availability the press 30

tonnage press is selected.

Press specification

Capacity Table size Shut height Stroke lengthRam

Adjustment

Stokes per

minute

Power

required

30 tons 450 x 500 275 mm 75 mm 30 mm 65 mm 3 H.P

Tool height:

Max. Tool height = Shut heightadjustment

= 27510

= 265 mm

Min. Tool height = Max. Tool height - Ram Adjustment

= 265 -30

= 235 mm

Optimum tool height = Min. Tool height + regrind allowance

= 235 + 15

=250 mm

Spring back

Due to the plastic-elastic forming of a work piece, there is a spring back at the end of a

bending process. When bending is done, the residual stresses cause the material to spring back

towards its original position, so the sheet must be over-bent to achieve the proper bend angle.


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The amount of spring back is dependent on the material, and the type of forming. The spring

back has to be compensated to achieve an accurate result.

The spring back angle also depends upon the bend angle and the material properties. A

spring back is compensated by two ways

1.

Over bending the sheet to get the proper bent angle.2. Bottoming or squeezing the material at the bend line.

In our project embossing gives the additional stiffness to the bend angle and it reduce the spring

back of the material. Based on the internal bending radius and tensile strength of the spring back

angle is selected from the table shown in P.H Joshi book (see reference)

For tensile strength 300 N / mm2 and Bending radius below the thickness of the sheet

Bend angle 90 60 30

Spring back angle 4.7 3.1 1.6

Die material:

According to ISO 4957: 1999, High carbon high chromium steels.

D2 is the popular choice of the tool makers material. It has good wear resistance, high toughness

and high dimensional stability.

Carbon Chromium Manganese Vanadium Molybdenum

1.55% 12.00% 0.45% 0.80% 0.85%

Density= 7700 Kg / mm3

Rockwell hardness =65

Poisons ratio =0.27-0.3

Elastic modulus = 190210 GPa.

Ultimate tensile strength = 260390 GPa

Hexagonal socket headed screw:

It is used to connect the bottom shoe and top shoe with the die sets.

Material Specification: ASTM A574M / DIN ENISO4762-alloy steel

Hardness: RC 3843

Max. Permissible stress on the threads: 120 N / mm2

No of Screws: 12


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Permissible stress=Loa on the single Screw

area of bolt on the crest

Load on one Screw =Total loa

No of Screw

=250 0

2

=20.83 x 103N

=P

dc2

4

dc2 =

20.3 X 0X

20 X

= 14.86mm

Major diameter of thread D =dc / 0.8

=18 mm (approximately)

M18Screw is selected

According to IS 22691967 and from the PSG data book Page No. 5.61 the various dimension

of the screw are selected.

Die sets:

Selecting the standard die sets from standard catalogue based on the size of the table and

availability. The standard provides that (all dimensions in mm)


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A B A1 C1 C2 E P

315 200 171 50 50 225 45

Pillar set:

Corresponding to the die set, the pillar set of 30 mm diameter should be recommended.

Pillar length = Tool heightRegrind allowance (two sides)

= 25040

= 210 mm

Bush set:

Corresponding to the die set, the bush set of 55 mm outer diameter and 30 mm inside diameter

has to be recommended.

Pillar length = (stroke length + Regrind allowance) + (Bolt thicknessBase allowance)

= (75 + 15) + (50 -20) = 90 + 30

= 120 mm


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MODEL:

Process:

Hexagonal socket headed screw:

Die set assembly:

Top view:


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Front view:

Isometric View:


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REFERENCES

Ivana Suchy Handbook of Die Design second edition McGrew-Hill publication, 2006,

ISBN 0-07-146271-6

Donaldson Tool design second edition.

P.H. Joshi Press ToolsRevised edition,S.Chand Publication,2008, ISBN81-219-2938-5

R.E Cowley die design fundamentals Second publication, 2000, ISBN 0-8311-1172-0

www.Wikipedia.com

www.google.com

http://www.westyorkssteel.com/tool-steel/d2

https://law.resource.org/pub/in/bis/S10/is.1079.2009.pdf
http://www.wikipedia.com/http://www.google.com/http://www.westyorkssteel.com/tool-steel/d2http://www.westyorkssteel.com/tool-steel/d2http://www.westyorkssteel.com/tool-steel/d2http://www.google.com/http://www.wikipedia.com/

design analysis of tools and process simulation for a sheet metal component

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