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Evaluation of Sheet Metal Covers to Improve Tool Life in Forging Prof. Dr.-Ing. L. Schaeffer*, J. Zottis, Dr. Ing. A. Brito, Laboratório de Transformação Mecânica UFRGS Prof. Dr.-Ing. G. Hirt, M. Wolfgarten*, Y. Yu Institut für Bildsame Formgebung RWTH Aachen University *Presenting authors

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  • Evaluation of Sheet Metal Covers to

    Improve Tool Life in Forging

    Prof. Dr.-Ing. L. Schaeffer*, J. Zottis, Dr. Ing. A. Brito,

    Laboratório de Transformação Mecânica – UFRGS

    Prof. Dr.-Ing. G. Hirt, M. Wolfgarten*, Y. Yu

    Institut für Bildsame Formgebung – RWTH Aachen

    University

    *Presenting authors

  • Slide 2

    Motivation

    Tooling costs stand up to 15-35% of total costs

    Main failure of forging die: abrasive wear

    Most failures appear on the surface

    Method of surface protection

    – Surface treatment (Nitriding, PVD…)

    – Coating

    – Die insert

    Tool repair and exchange is still required

    To protect forging tool, decrease tooling costs

    Inspired by the exchangeable cutting tool insert

    For Making the surface of forging die

    “exchangeable”

    Wear

    Mechanial

    fatigue

    Plastic

    deformation

    Thermal

    fatigue

    Failures

    Out of use

    Hot forging die Forging

    Traditional forging

  • Slide 3

    Motivation

    Inexpensive and easy-to-exchange sheet metal

    as a protective die cover

    Die cover concept

    – Failures will only affect die covers

    – Can be exchanged quickly

    – Thermal load will be reduced

    – Economical

    Fix the die cover Forging

    Take out forging

    pieces

    Take out the die cover

    after N forging pieces

    Out of use

    Recycle use

    Forging die

    Forging with die covers

  • Slide 4

    Motivation

  • Slide 5

    Conclusions from the previous project stage

    Materials were selected based upon their mechanical and

    thermal properties.

    Different geometries were developed to define the

    application range of this concept.

    The protection effect of die covers was proved both by

    simulations and experiment.

    Two geometries were validated by experiment and the die

    cover reached 10 forging cycles.

    Open questions:

    – Wrinkling and thinning problems

    – Application on more complex geometries

  • Slide 6

    Objectives of the 2nd phase

    Investigation of possibilities to improve the boundary

    conditions

    – Influence of the friction coefficient on the tensile stresses

    within the die cover

    – Test of enhanced sheet fixation

    Development of a suitable die geometry

    – Investigation of 3D geometries

    – Investigation of axisymmetric geometries

    Investigation of multi-stage forging processes

    – Analysis of multi-stage forging process with reduced

    tangential movement in forging stages

    – Investigation of the “finisher” step

  • Slide 7

    General information

    Publications

    – Publications in Journals:

    First experimental and numerical study on the use of sheet metal die covers for wear

    protection in closed-die forging (Key Engineering Materials Vols 651-653 (2015) pp 266-271)

    Estudo da aplicabilidade de máscaras metálicas de DP600 em superfícies de matrizes de

    forjamento (Revista Ferramental. ed 66, p27-32. Curitiba, 2016)

    – Conference Proceedings:

    Influence of the Die Geometry on the Application of a Sheet Metal Cover for Wear Protection

    in Closed Die Forging (35th SENAFOR)

    Influence of Die Geometry and Material Selection on the Behavior of Protective Die Covers

    in Closed-die Forging (ESAFORM 2016)

    Characterization of DP600 Sheet Mechanical Properties and Anisotropy (15th ENEMET –

    ABM)

    Study of DP600 metallic mask applicability in forging die surface (36th SENAFOR)

    Temperature influence on DP600 sheet hardness to metallic mask application in Hot Forging

    (36th SENAFOR)

    Hot Forging Process Analysis Using a Metallic Mask as Surface Coating (22th Cbecimat)

  • Slide 8

    General information

    Work missions

    – Brazil: Prof. Dr.-Ing. L. Schaeffer

    – Germany: M. Wolfgarten, Y. Yu

    Student missions

    – Brazil: Master Student A-K. Haussmann

    – Germany: Doctoral Student J. Zottis; Master Student T. M. Ivaniski

    Post-Doctor

    – Prof. Dr. Eng. A. Brito (Brazil Germany)

    Students

    – Bachelor students: A. Seeliger and N. Adrian (Germany); A. Rosiak, G. Graziottin and

    H. Kemmerich (Brazil)

    – Master students: E. Segebade, S. Böhnke (Germany), T. M. Ivaniski (Brazil)

    – Doctoral students: Y. Yu (Germany); L. de L. de Costa (Brazil), J. Zottis (Brazil Germany)

  • Slide 9

    Investigation of 3D geometries

    Comparison of 2D die cover and 3D die cover

    2D die cover

    – Easy to form

    – Wrinkling and thinning problems

    – Material of billet flows around the die cover

    3D die covers

    – Need more complex manufacture process

    – More stable2D die cover 3D die cover

    Billet

    Die cover

    Forging die

    Problem of 2D die cover

    Material flows around the die cover 2D die cover 3D die cover

  • Slide 10

    Two ideas to explore 3D die covers

    From existed sheet metal parts to forging parts

    – Advantages: die cover manufacture process already existed

    From the geometry to the manufacture of die cover

    Investigation of 3D geometries

    Square flange

    Cross forging

  • Slide 11

    Investigation of 3D geometries

    Two ideas to explore 3D die covers

    From existed sheet metal parts to forging parts

    – Cross die

    Material flow mainly perpendicular to forging direction

    1 2

    3 4

    Forming progress Material flow

    Cross sheet part

    Cross forging part

  • Slide 12

    Investigation of 3D geometries

    Experimental validation

    – Material: 22MnB5

    – Die covers manufactured by deep drawing

    Drawing depth: 30 mm

    – Heat treatment

    Heating above 830°C, then cooling

    -0.34

    0.26

    mm

    0

    Comparison of the die cover before and after heat treatment

    0

    200

    400

    600

    800

    1000

    0 200 400 600T

    em

    pera

    ture

    in

    °C

    Time in s

    900°C

    Heat treatment curve

    Deep drawing

  • Slide 13

    Investigation of 3D geometries

    Experimental validation

    – Billet: C45

    – Dimension: 50*50*75 mm

    – Lubricant: graphite

    – 10 forging cycles

    Lubrication Positioning billet Forging Taking off billet

    2 s5s10 s 34 s

    Waiting

    30 s30s

    Forging process

  • Slide 14

    0

    200

    400

    600

    800

    1000

    1200

    1400

    1600

    1800

    0 0,5 1 1,5 2

    Fo

    rce

    in

    KN

    Time in s

    experiment

    simulation

    Investigation of 3D geometries

    Two ideas to explore 3D die covers

    From the existed sheet metal part to the forging part

    – Cross die

    Maximum stress: 1372 MPa

    0

    700

    1400

    Von Mises stress

    Unit: MPa

    Maximum point

    1372 MPa

    Stress distribution Press force

  • Slide 17

    Investigation of 3D geometries

    Experimental validation

    – 10 forging cycles

    – Stable state: 350°C to 450°C

    Conclusions

    – The 3D die covers are more stable than the 2D die covers

    – The die cover made by 22MnB5 has more than 10 cycles

    service life

    – Easy to put in and take off is possible in this case

    – More cases with similar material flow ways can be explored

    as the applications

    Die covers before and

    after heat treatment

    Die covers before and

    after 10 forging cycles

  • Slide 18

    Idea two: from the geometry to the manufacture of die

    cover

    Idea of how to design the new geometry

    – Keeping the cross section same with 2D geometries

    – Considering the limitation of manufacture methods (deep

    drawing and incremental forming)

    – Nonaxisymmetrical

    2D geometries in phase 1 3D geometries design The selected 3D geometry

    Supporting tool for incremental forming

    Investigation of 3D geometries

  • Slide 19

    Investigation of 3D geometries

    New 3D geometry

    – Press force: 270 t

    – Maximum stress: 1292 MPa

    – Die cover manufacture: incremental forming

    – Material: 22MnB5

    0

    700

    1400

    Von Mises stress

    Unit: Mpa

    Stress distribution Incremental forming of die cover

  • Slide 20

    X: 15.6727

    Y: 4.96127e+06

    Investigation of axisymmetric geometries

    – Numerical investigation to determine suitable geometries

    – Investigation of manufacturing strategies for the die cover

    – Evaluation of die wear by forging experiments

    3D axisymmetric geometries

    – Forging force analysis

    – Billet size

    – Experimental plan

    Investigation of 3D geometries

    Gear Blanks

    Ø150x50 mm

    Numerical evaluation – billet size

    Axisymmetric geometry

  • Slide 21

    3D axisymmetric geometries

    – Numerical simulation results

    Using a sheet metal as a die cover – 22MnB5

    Without die cover

    – Maximum temperature of the lower die on surface decrease

    from 640°C to 320°C

    – von Mises stresses decrease from 700 MPa to 380 MPa.

    Investigation of 3D geometries

    Die cover (22MnB5 with 1.5 mm thickness) after one forging cycle

    Temperature (°C)

    Temperature (°C)

    Without Die Cover

    Without Die Cover

    With Die Cover

    With Die Cover

    Stress – Effective (MPa)

    Stress - Effective (MPa)

  • Slide 22

    Investigation of manufacturing strategies for the die cover

    – Incremental Sheet Forming

    Different materials

    DP600

    22MnB5 (before treatment)

    DC04

    Manufacturing of a supporting tool (forging tool)

    Process parameters:

    Offset = 0.5 mm (Z)

    Velocity = 4000 m/s

    Tool size

    1st 20 mm

    2nd 10 mm

    Die cover measurements:

    3D scan

    Optical 3D (ARGUS 5M)

    Investigation of 3D geometries

    First Path – tool 20 mm

    Second Path – tool 20 mm

    ab

    c d

    Holder

    Sheet

    material

    Supporting

    tool

    Final Geometry – tool 10 mm

  • Slide 23

    Incremental Sheet Forming

    – Equipment: Amino

    – Fixation

    Bottom of Supporting tool

    Structure for lateral stability

    Investigation of 3D geometries

    FixationMaterial thickness samples

    DC04 1mm 3

    1.5mm 3

    DP600 1mm 3

    22MnB5-coated (before quenching) 1mm 6

    1.5mm 3

    Samples number of manufactured covers

    with different thickness.

  • Slide 24

    Incremental Sheet Forming

    – Equipment: Amino

    – Manufacturing steps:

    First path with 20 mm of tool diameter

    Second path with 10 mm of tool diameter

    Investigation of 3D geometries

    ISF Process Final Step

    Manufactured Die Cover

  • Slide 25

    3D die covers measurements

    – A PDA grid pattern or mesh printed by Laser on the bottom

    surface of sheet metal before incremental forming process

    (ISF).

    – Optical 3D measurement system (ARGUS 5M) was used to

    evaluate the final thickness of the manufacture die cover.

    – For the DP600 formed material, can be observed higher

    reduction in the die cover walls.

    – ISF process could provide an accurate final geometry.

    Investigation of 3D geometries

  • Slide 26

    3D axisymmetric geometries

    – Experimental plan

    Investigation of 3D geometries

    1. Forging Experiment Set and lubrication

    2. HeatingBillet – 45 min

    Dies – 20 min

    3. Billet Transfer ~ 30 s

    4. Positioning and Start ~ 10 s

    5. Forging Operation 15 mm (stroke Z)

    6. Extraction and lubrication ~ 60 s

    Cover Materials

    DC04

    22MnB5

    DP600

    Forging cycle for each cover sample N = 4

  • Slide 27

    Test of enhanced sheet fixation

    Test of enhanced sheet fixation

    – High temperature glue (long curing time)

    – Mechanical fixing

    Mechanical fixations

    Fixation effect in simulation Holder used as a

    mechanical fixation

    Holder

    Die cover

    Lower die

    Fixation

    Fixation

  • Slide 28

    Outlook

    Investigation of possibilities to improve the boundary

    conditions

    – To validate the friction results in experiment using different

    topography

    Development of a suitable die geometry

    – To explore the max service life of die cover in different

    geometries

    – Evaluation of die wear

    Investigation of multi-stage forging processes

    – Analysis of multi-stage forging process with reduced

    tangential movement in forging stages

    – Investigation of the “finisher” step

    Different topography

  • Slide 29

    Thank you for your attention!