Evaluation of Sheet Metal Covers to Improve Tool Life in Forging

Transcription

1 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

2 Motivation Tooling costs stand up to 15-35% of total costs Out of use Hot forging die Thermal fatigue Traditional forging Plastic deformation Wear Mechanial fatigue Failures Forging 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 Slide 2

3 Motivation Forging with die covers Inexpensive and easy-to-exchange sheet metal as a protective die cover Fix the die cover Recycle use Forging Die cover concept Failures will only affect die covers Can be exchanged quickly Thermal load will be reduced Economical Forging die Out of use Take out forging pieces Take out the die cover after N forging pieces Slide 3

4 Motivation Slide 4

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 5

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 6

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 (2015) pp ) Estudo da aplicabilidade de máscaras metálicas de DP600 em superfícies de matrizes de forjamento (Revista Ferramental. ed 66, p 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 (15 th 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 7

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 8

9 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 2D die cover 3D die cover 3D die covers Need more complex manufacture process More stable Billet Die cover Forging die Problem of 2D die cover Material flows around the die cover 2D die cover 3D die cover Slide 9

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 Cross forging Square flange Slide 10

11 Two ideas to explore 3D die covers Cross sheet part From existed sheet metal parts to forging parts Cross die Material flow mainly perpendicular to forging direction 1 2 Cross forging part 3 4 Forming progress Material flow Slide 11

12 Temperature in C 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 Deep drawing mm Comparison of the die cover before and after heat treatment C Time in s Heat treatment curve Slide 12

13 Experimental validation Billet: C45 Dimension: 50*50*75 mm Lubricant: graphite 10 forging cycles Lubrication Positioning billet Forging Taking off billet Waiting 10 s 30s 5s 2 s 34 s 30 s Forging process Slide 13

14 Force in KN Investigation of 3D geometries Von Mises stress Unit: MPa 1400 Two ideas to explore 3D die covers From the existed sheet metal part to the forging part Cross die Maximum stress: 1372 MPa 700 Stress distribution 0 Maximum point 1372 MPa experiment simulation 0 0,5 1 1,5 2 Time in s Press force Slide 14

15 Experimental validation 10 forging cycles Stable state: 350 C to 450 C Die covers before and after heat treatment 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 10 forging cycles Slide 17

16 Idea two: from the geometry to the manufacture of die cover Supporting tool for incremental forming 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 Slide 18

17 Von Mises stress Unit: Mpa New 3D geometry Press force: 270 t Maximum stress: 1292 MPa Die cover manufacture: incremental forming Material: 22MnB5 0 Stress distribution Incremental forming of die cover Slide 19

18 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 Axisymmetric geometry 3D axisymmetric geometries Forging force analysis Billet size Experimental plan X: Y: e+06 Ø150x50 mm Numerical evaluation billet size Gear Blanks Slide 20

19 With Die Cover Temperature ( C) 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. With Die Cover Without Die Cover Stress - Effective (MPa) Die cover (22MnB5 with 1.5 mm thickness) after one forging cycle Temperature ( C) Stress Effective (MPa) Without Die Cover Slide 21

20 Investigation of manufacturing strategies for the die cover First Path tool 20 mm c d a b Second Path tool 20 mm Holder Sheet material Supporting tool 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 1 st 20 mm 2 nd 10 mm Die cover measurements: 3D scan Optical 3D (ARGUS 5M) Final Geometry tool 10 mm Slide 22

21 Incremental Sheet Forming Equipment: Amino Fixation Bottom of Supporting tool Structure for lateral stability Fixation Samples number of manufactured covers with different thickness. Material thickness samples 1mm 3 DC04 1.5mm 3 DP600 1mm 3 1mm 6 22MnB5-coated (before quenching) 1.5mm 3 Slide 23

22 Incremental Sheet Forming Equipment: Amino Manufacturing steps: First path with 20 mm of tool diameter Second path with 10 mm of tool diameter Manufactured Die Cover ISF Process Final Step Slide 24

23 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. Slide 25

24 3D axisymmetric geometries Experimental plan 1. Forging Experiment Set and lubrication 2. Heating Billet 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 DC04 Cover Materials 22MnB5 DP600 Forging cycle for each cover sample N = 4 Slide 26

25 Test of enhanced sheet fixation Test of enhanced sheet fixation High temperature glue (long curing time) Mechanical fixing Fixation effect in simulation Holder used as a mechanical fixation Fixation Holder Die cover Fixation Mechanical fixations Lower die Slide 27

26 Outlook Investigation of possibilities to improve the boundary conditions To validate the friction results in experiment using different topography 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 Slide 28

27 Thank you for your attention! Slide 29