Analysis of Punch and Die for Forming Sheet metal ... · Analysis of Punch and Die for Forming...

International Journal of Trend in Research and Development, Volume 3(5), ISSN: 2394-9333

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IJTRD | Sep-Oct 2016 Available [email protected] 342

Analysis of Punch and Die for Forming Sheet metal

component using Finite Element Method 1Raghavendra,

2U.N. Kempaiah,

1ME Student,

2Professor,

1,2Mechanical Engineering Department, University Visveswaraya College of Engineering, Bangalore, Karnataka, India

Abstract — This paper presents Static structural analysis for

forming Punch and Die using Finite Element analysis technique

for an aerospace sheet metal component. Sheet metal

components are manufactured by applying the force on the blank

placed between Punch and Die using a Press Tool. Necessity for

the structural analysis of Press Tool components like Punch and

Die are very much needed. The design of the Press Tool

components is done using Catia Software by considering

geometry of the component to be produced and complexity

involved. Analysis statically before releasing for manufacturing

helps in finding out possibilities of failure in the design of Punch

and die and also to optimize. A Press Tool for sheet metal half

duct component is designed and analyzed for its structural

strength of Punch and Die using Catia Structural Analysis

capability. Von-Mises stresses are considered for the failure

study. The Finite Element Analysis helps in optimizing the

design by avoiding trails and errors, recognizing Problem areas,

critical regions and maximum deformed areas with a reduced

design cycle time.

Index Terms — Finite Element Analysis, Forming, Static

Structural Analysis

I. INTRODUCTION

Sheet metal forming is a complex deformation process

carried out on Press Tool using different forming methodology.

Press tool is a device used to perform cutting, non-cutting and

hybrid operations on a sheet metal blank. Forming press Tool is

used to achieve the final shape of the desired contour by

deforming the blank with the set of Punch and Die. Punch and

Dies are the Male and Female portion of the component to be

produced. Forming is an operation where shaping of the metal

for the final contour requirement is processed through nonlinear

axis.

In this process the blank of sheet metal component is subjected

to plastic deformations. It is a non-cutting operation where

material is subjected to forming loads. Sheet metal blank is

placed on the stripper plate between the Punch and Die and the

final component is confined to the shape of Punch and Die.

While forming, the Die descends and gradually hits the sheet

metal and takes the shape of Punch in a Press.

During design of Press Tool components, the major tool

components like Punch and Die are to be optimized with respect

to the design parameters to eliminate failure and to ensure safety

during the production stage.

Finite Element analysis is applied in the design of Punch and

Die to make the design more efficiently by avoiding failures for

the respective loads before production release. By analyzing the

Finite Element Analysis result we can predict the critical areas of

failures and compensations to be considered during the design

process.

II. COMPONENT STUDY

Fig 1 shows the Sheet metal component 3D model required to

be formed by the Press forming process. Thickness of the

component to be produced is 1mm. Contour surface of the model

is a complex 3D surface and forming is a nonlinear deformation

process. Forming process planning is done and decided that, part

has to be altered for the forming feasibility.

Fig 1 Component

The component altered for the forming is done by keeping

curvature continuity considerations. Modified geometry for

forming operation is as shown in the fig 2. The model is modified

for the forming flow easiness and we observe in the 3D model

that component to be formed is extended in both the directions.

Fig 2 Modified Component for Forming Operation

III. TOOL DESIGN

During designing the tool, Sheet Thickness for design

calculations, Machine specifications for deciding tool size,

critical dimensions, complexity of component, Number of

components to be produced, Number of stampings to be made

and Component Material properties, Punch and Die material

properties are considered.

Tool Calculations:

Forming Tool Force calculations are done manually and the

same is applied for the static structural analysis.

Forming Tool Force

Forming Force Required= Component thickness (mm)


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x Forming length in X and Y axis (mm)

x Ultimate Tensile Strength (N/mm2)

=1 x (329.556+478.97) x 750

=606394.5N

=61.83 Tons

Binder Force = 25% of forming force

= 0.25 x 61.83

= 15.45 Tons

Total Forming force = Forming force + Binder force

= 61.83 + 15.45

= 77.28 Tons

Press Selection = Forming Force / Press efficiency

= 61.83 / 0.7

= 88.32Tons

Based on the calculation 100 Tonnage capacity press is used

for the realization of the part try-out.

Forming Tool:

3D Model is created using Catia software. The assembly of

Press tool components such as punch, die and Stripper plates are

shown in the Fig 3. 3D models for the forming tool are

assembled separately for the top, bottom and stripper plate

assemblies and analyzed for clashes and for other first order

defects in the assembly. Detailed drawing of each forming tool

components are drawn using Catia drafting work bench for the

production standard.

Fig 3 Forming Press Tool

Fig 4 Exploded View of Press Tool

Exploded view of the press tool is shown in the Fig 4. The

view clearly displays the shape and position of the press tool

components in an assembly order.

Fig 5 Forming tool Die

Fig 6 Forming tool Punch

Forming Punch and die are shown in the Fig 5 and Fig 6. Die

portion of the tool is treated as female part and the Punch is

treated as male portion of the tool. Inverted Die descends and

press the blank on the Punch with a support of Stripper Plate.

IV. STATIC STRUCTURAL ANALYSIS OF PUNCH

AND DIE

The analysis is carried out by the help of Catia CAE

application software using FEA Method. The 3D models which

are having critical functionalities are analyzed for its structural

strength and failure. Punch and die are considered as critical

components and analyzed for its static strength by applying

different constraints like material properties, boundary

conditions, forming Pressure load etc.

FEA methodology is generally preferred to reduce physical

try-out, design lead time and for economical production. It helps

in solving complex problems with irregular shapes, different

materials, complex boundary and load conditions easily.

Punch and die Material used for Forming Press tool:

Material used for punch and die: OHNS

Young modulus: 193000MPa

Poisons ratio: 0.3

Density: 7660kg_m3

Yield Strength: 1800Mpa Element Type: Octree tetrahedron Solid Mesh

Tetrahedron meshes are preferred generally for solid 3D models

for both static and dynamic analysis for surface pressure loads.

For the Static Structural analyses of Punch and Die for the

forming operation are meshed in two stages for smaller and large

surface areas. The Global mesh of size 5mm with a sag value of

0.1mm is used for longer surface areas and smaller surface areas


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are meshed using fine mesh size of 1mm and with a sag value of

0.05mm for fillet areas to get better approximated results.

Analysis of Punch for forming operation

Fig 7 shows the Pressure applied to the punch face by the arrows

and Boundary conditions can be seen in the bottom face of the

Punch where it is going to fix in the Back plate.

The Pressure = 6.135MPa is applied based on forming Load of

606394.5N and corresponding contact area on Punch.

Fig 7 Punch Boundary condition

Fig 8 shows the Forming punch mesh globally and also with a

fine mesh in the smaller fillet areas. Meshes can be made still

finer in all the areas by considering the criticality of load and

pressure acting during the forming process.

Fig 8 forming Punch Mesh

Von Mises stresses are considered as a failure theory and

analysis results are found to be within the safe region. Fig 9

shows the Von Mises stress distribution value display. The color

display clearly shows that the Punch is well within the structural

stability limit.

Fig 9 Von Mises Stress of forming Punch

Fig 10 shows the displacement found in the punch during FEA

analysis and results are tabulated in the table 1. Areas which are

on the Punch surfaces are deformed in a micron level and more

quantity of parts can be produced with the Punch material

selected since it is an Oil Hardened Non Shrinkable material

with a higher Yield strength value. The Punch wear and tear

would be very less as the displacement is having too low values.

Wear and tear analysis of Punch can be made in detail by

considering production quantity.

Fig 10 Static Displacement of Forming Punch

Analysis Results:

Table1: Form Punch Von-Mises Stress results

Objective Von-Mises Stress

(MPa)

Displacement

(mm)

Minimum 0.0962 0

Maximum 6.99 0.0024

Analysis of Die for forming operation:

Forming die is analyzed for its structural strength by

considering forming load and pressure. Die is the female portion

of the press tool where it is going to experience the repeated

loads as Punch.

Applied Load: 606394.5N

Fig 11 forming Die Mesh

Fig 11 shows meshing for the forming Die and again the areas

are meshed in two methodologies for larger and smaller surface

areas with the same concept of Punch meshing.

Fig 12 forming Die Boundary condition

Fig 12 shows the Boundary conditions and pressure exerted

area in the Die component. Arrow represents the Pressure acting

areas and the support or the boundary conditions can be seen in


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the bottom face where it is going to fix with top plate of the Die.

Fig 13 Von Mises Stress of forming Die

Von Mises distribution is shown in the color display Fig 13 and

we can observe that it is showing very low value compared to the

yield stress value of the material selected. Hence the design is

very much safe as far as static loads are considered.

Fig 14 Static Displacement of Forming Die

The translational displacements are displayed in Fig 14 and

results are analyzed and tabulated in Table2.

Analysis Results:

Table2: Forming Die Von-Mises Stress results

Objective Von-Mises Stress

(MPa)

Displacement

(mm)

Minimum 0.01 0.0004

Maximum 10.7 0.0046

The results shown in Table 1&2 for Von Mises stress results

induced in punches and dies are less than the yield stress of

material used. Hence the design is safe.

Fig 15 Trimming Fixture

V. INSPECTION

Inspection and Validation of the component is done for the

trimmed component against CAD Model. Since the part is of

complete 3D surface and there is no datum for the inspection

reference, dimensional inspection methodology not preferred

unless the part inspected by the help of a template for each

sections. So the methodology of Cad model surface is adopted

for the inspection purpose.

CAD Model inspection is a methodology where the complete

geometry of the component surface is probed by the help of

articulated portable inspection equipment and compared against

the CAD Model. The CAD Model Inspection is carried out by

following steps.

Setup of the portable arm on the surface plate using

Magnetic plate setup.

Initializing and homing of the instrument through

Inspection software.

Importing CAD Model to the computer interface

Aligning of CAD Model with the actual part by Free Form

alignment methodology by taking minimum of 6-8 points

on the component surface.

Probing of the part using articulated Robotic arm as shown

in Fig 16.

Comparing the probed points against CAD Model.

3 Dimensional deviations with respect to the CAD Model

are computed as shown in Fig 17.

Fig 16: Inspection Using Articulated Robotic Arm

Fig 17 Surface deviation observed during Cad Model Inspection.

RESULTS AND DISCUSSION

The Punch and Die components are manufactured and

component is produced using forming press tools by tryouts

considering punch and die structural analysis carried out based

on the Finite Element Analysis Methodology and proved that,

the design is safe. Components are produced by tryouts are

validated against the CAD Model and found that the parts are

within the tolerance limit of the part conformity.

The scope for Dynamic structural analysis by considering all

types of loads throughout forming helps in evaluating the

analysis more thoroughly.

References

[1] Cynthia M. Tamasc, Masoud Rais-Rohani and Arjaan

Buijk,2011,“Sheet-Stamping Process Simulation and

Optimization”, AIAA 2011-2146, 52nd

AIAA/ASME/ASCE/AHS/ASC Structures, Structural

Dynamics and Materials Conference.


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[2] Ulhas K Annigeri, Y P Deepthi, Raghavendra and Ravi

kiran k,2014,” Design, Development and analysis of

forming tool for side panel of an Automobile”, International

Journal of Mechanical and Production engineering,

ISSN:2320-2092, Volume-2, Issue-6.

[3] Kalyani Abhinav and Prof. K. Annamalai, 2013, “Analysis

of sheet metal bending by using Finite Element Method”,

International Journal of Engineering Research &

Technology (IJERT), ISSN: 2278-0181, Vol. 2 Issue 1.

[4] Fundamentals of sheet metal formability by Altair

Engineering Inc.

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