23 Experimental and Simul

8/12/2019 23 Experimental and Simul

1/24

Universit di BresciaUniversit di Brescia Dipartimento di Ingegneria MeccanicaDipartimento di Ingegneria Meccanica

Tecno logie e Sistemi d i LavorazioneTecno logie e Sistemi d i Lavorazione

11InternationalInternational ConferenceConference INNOVATIONS IN METAL FORMING (23INNOVATIONS IN METAL FORMING (23--2424 SeptemberSeptember20042004 BresciaBrescia -- Italy)Italy)

ExperimentalExperimental andand SimulativeSimulative ResultsResultsofof NeckingNecking OperationOperation

on Aluminium Canon Aluminium Can

ByBy

R. FrattiniR. Frattini

(Frattini S.p.A., Seriate, Italy)(Frattini S.p.A., Seriate, Italy)

A.A.AttanasioAttanasio, C., C. ContriContri, E. Ceretti, C., E. Ceretti, C. GiardiniGiardini

((DipartimentoDipartimentodidi IngegneriaIngegneriaMeccanicaMeccanica, Universit, Universit deglidegliStudiStudidi Brescia, Italy)di Brescia, Italy)

Thursday, September 23, 2004Thursday, September 23, 2004


2/24




1. Frattini S.p.A.2. Production.3. Necking Operation.4. Objectives.5. The FE Model6. FE Model Validation:

I. Evaluation of m.II. Thickness comparison.III. Can height comparison.IV. Axial force.

7. Conclusion.8. Future work.

OutlineOutlineOutline


3/24




Frattinis history began more than 80 years ago, in 1920, whenthe 4 Frattini brothers started on a machinery business inBergamo.The third generation (1994) takes its managing responsibilitiescontinuing the companys traditional philosophy which is radically

oriented to customers service & technology.

1. Frattini S.p.A.1.1. Frattini S.p.A.Frattini S.p.A.

[Frattini S.p.A.]


4/24




Frattini S.p.A. is a world wide leader company in the field ofmachines for deformation of aluminium monobloc containers

through ironing and necking machineries.

2. Production2.2. ProductionProduction

[Frattini S.p.A.]


5/24




Necking is a cold forming process in which the open end of ashell or tubular component is closed by axial pressing with a

shaped die.Necking is obtained by multistage mechanic presses.

[Altan et al., 1983]

3. Necking Operation3.3. Necking OperationNecking Operation

[Frattini S.p.A.]


6/24




The analyzed necking operation, object of this research, isobtained by a Frattini S.p.A. machine with 26 necking dies.

3. Necking Operation3.3. Necking OperationNecking Operation

[Frattini S.p.A.]


7/24




This research is a cooperation between Frattini S.p.A. and the

Technology and Manufacturing System Group of the University ofBrescia with the aim of:

Determining the process parameters used in the FE Analysisfor the necking of a D&I aluminum can.

Comparing experimental and simulative results in order tovalidate the FE model (on the basis of geometrical and forceparameters).

Optimizing the necking process according to the simulativeresults (to improve the product quality and decrease the totalnumber of steps).Using the FE code to design new neck profiles.

4. Objectives4.4. ObjectivesObjectives

U i i di B i Di i di I i M i


8/24




Because of the can symmetry

the FE Analysis has beenconducted using the axisymmetricgeometry type available in theimplicit commercial code DEFORM2D.

Die and can geometries

together with the processparameters have been providedby Frattini S.p.A.

ClampingClamping GripGrip

Aluminium CanAluminium Can

NeckingNecking DieDie

5. FE Model5.5. FE ModelFE Model

U i it di B iU i it di B i Di ti t di I i M iDi ti t di I i M i


9/24




The initial can height is 194.8 mm, the outside diameter is 53 mmand the wall thickness is 0.22 mm.

To obtain the final neck profile 26 necking steps are necessary.

Can

Necking Die




10/24




The material of the can is Al3004 and its characterization has beendone in a previous research made with Brescia University.


70,000 [MPa]E

2.8*10-6 [cm3/kg]

0.0547n389.14 [MPa]K

290 [MPa]y

s= 389.14e0.0547

0

50100

150

200

250300

350

400

450

0 0,01 0,02 0,03 0,04 0,05

[MPa]



11/24




The validation of the FE Model is necessary for the further processoptimization.In order to reach this goal the following experimental andsimulative parameters have been evaluated and compared:

Can Wall Thickness.Can Height.Axial Force.

The validation has been carried out changing the friction factor mwhich represents the lubrication conditions at the die can interface.

6. FE Model Validation6.6. FE Model ValidationFE Model Validation



12/24




In fact, the first problem to solve to simulate the actual neckingprocess was the evaluation of the friction factor (m) by means ofseveral simulations run with different m values.

The can wall thickness and the can height comparison betweenthe simulation results and the experiments allowed thedetermination of the correct m value.




13/24




Wall thickness comparison with different m values

0,2200,2220,2240,2260,2280,2300,2320,2340,2360,2380,2400,2420,244

0,2460,2480,250

1 2 3 4 5 6

# Necking Die

Wallthickness[mm]

From Experiments

m=0,001

m=0,0025

m=0,005

m=0,0075

There is a good agreement between experimental wall thickness

values and simulative ones when m is equal to 0.005.




14/24




Wall Thickness Comparison (1)

0,200

0,2250,250

0,275

0,300

0,325

0,350

0,375

1 6 11 16 21 26

# Necking Die

Wall

Thickness[m

m]

From Simulation

From Experiments

Up to the necking die #18 simulation results match very well with

the simulative ones.

6.II Wall Thickness Comparison6.II6.II Wall Thickness ComparisonWall Thickness Comparison

18



15/24

p g gp g g




-4

-2

0

2

4

6

8

10

12

1 6 11 16 21 26

# Necking Die

%Sim.-Exp.Wall

T

hickness

After the necking die #18, the % difference between simulativeand experimental thicknesses increases. This may be due to anexcessive thickening of the top of the necked can.


18



16/24

p g gg g



Analyzing the actual productive process it was found that the cantop is cut four times (after the necking dies #6, #12, #18 and#22).A new simulative campaign has been performed introducing in

the model the cut of the can top edge.The so obtained simulative results match very well with theexperimental ones.




17/24




0,2

0,225

0,25

0,275

0,3

0,325

0,35

0,375

1 6 11 16 21 26

# Necking Die

WallThickness[

mm] From Experiments

From Simulation

In the picture the very good agreement between simulation andexperiment is shown in terms of can wall thickness.




18/24



Can Height Comparison

180

190

200

210

220

1 6 11 16 21 26# Necking Die

Canheight[mm]

From Experiments

From Simulation

The picture shows the same good agreement in terms of canheight.

The cut of the can edge is highlighted by the red circles.

6.III Can Height Comparison6.III6.III Can Height ComparisonCan Height Comparison


T l i Si i d i L i


19/24



Unless the axial force is different for each necking die, it ispossible to define a common force profile with a maximum initial

value followed by a lower average one.

Axial Force (Necking Die #6, m=0.005)

0

200400

600

800

1000

1200

0 10 20 30 40

Necking Die Displacement [mm]

Axia

lForce[N]

Maximum Force

Average Force

6.IV Axial Force6.IV6.IV Axial ForceAxial Force


T l i Si t i d i L iT l i Si t i d i L i


20/24



Analyzing the overall FE force results it is possible to see anincrease in the force after the necking die # 19.

Axial Force

0

600

1200

1800

2400

3000

1 6 11 16 21 26

# Necking Die

Ax

ialForce[N]

Maximum Force

Average Force


19




21/24




The force increase may be due to:

An incorrect material model (the material work hardening istoo high).

A can mesh with insufficient density (few elements in thethickness dimension).

A too simplified process modelling (the internal part of thenecking die in the actual process is moving so the frictionconditions are different).




22/24



7. Conclusion7.7. ConclusionConclusion

To increase the model reliability an

additional experimental campaignis in progress measuring for eachstep:

The can wall thickness.

The can height.

The axial force.

[Frattini S.p.A.]




23/24



The performed simulations of the necking process provide a good

picture of the actual process in terms of can wall thickness andgeometry.

It was necessary to introduce, in the simulation, the cut of the

can top edge to avoid excessive increase of the can thickness andof the necking force.

To be able to use the FE results to reduce & optimize the numberof necking steps it is necessary to improve the model reliability interms of axial force previsions.

7. Conclusion7.7. ConclusionConclusion




24/24



To reduce & optimize the numberof dies necessary for the necking

operation considering the FEsuggestions.To increase the product quality

and simulate new neck profiles.In this way new operations couldbe done by the Frattini machinesuch as:

Full Shaping body.Hydroforming.

8. Future Work 8.8. Future WorkFuture Work

[Frattini S.p.A.]

Documents

23 Experimental and Simul