Dr. Gerhard H. Arfmann, Dr. Michael Twickler CPM GmbH, Herzogenrath, Germany

Transkript

1 The Use of Simulation to predict Tool Failure in Cold Forging Processes Dr. Gerhard H. Arfmann, Dr. Michael Twickler CPM GmbH, Herzogenrath, Germany (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 1

2 Why to study FEA applications in metal forming es under the aspect of tool failure? Motivation: The prediction of tooling failure is not a standardized application of simulation in industry. Successful applications had to be studied to find out guidelines to support the design engineer. By getting experience from these studies rules should be given to enable the design engineer to foresee problems in future and therefore avoid costs and development time. The design engineer shall be enabled to develop long lasting tooling by using simulation instead of costly trial and error procedures. The study focused on real applications in industry to give most practical guidelines. The presentation shows such successful industrial applications. (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 2

3 Die failure in a multi station cold forming The customer faced severe tool failure in operation four of a five station. What can be optimized to get better tool life? (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 3

4 Die failure in a multi station cold forming The five station (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 4

5 Die failure in a multi station cold forming The five station Initial tool design in operation 4 (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 5

6 Die failure in a multi station cold forming The five station Forming in operation 4 (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 6

7 Die failure in a multi station cold forming Initial design of the die in operation 4 (carbide pre stressed with a single ring) The five station (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 7

8 Die failure in a multi station cold forming The five station Pressure on the carbide (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 8

9 Die failure in a multi station cold forming The five station Positive axial stress in the carbide => tool failure (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 9

10 Die failure in a multi station cold forming new design of the die in operation 4 (carbide split pre stressed with two rings) The five station (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 10

11 Die failure in a multi station cold forming The five station Still positive axial stress in the carbide => tool failure (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 11

12 CPM Gesellschaft für Computeranwendung, Die failure in a multi station cold forming The five station Tool breakage persists (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 12

13 Die failure in a multi station cold forming new design idea of the die in operation 4 (Disc made of ASP 30 carbide pre stressed with two rings) The five station (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 13

14 Die failure in a multi station cold forming corrected new design of the die in operation 4 (Disc made of ASP 30 carbide and disk pre stressed with two rings)- corrected by toolmaker The five station (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 14

15 Die failure in a multi station cold forming The five station Simulation shows compressive stress - tool life increased from to pieces (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 15

16 Die failure in a multi station cold forming Result: Systematic analysis of the various design ideas leads to better tool design and better understanding of the design. Testing on the machine can be avoided. The five station Design rules could be reviewed. Future designs can be made better by using FEA from the beginning and considering the new design rules. (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 16

17 Punch failure in a multi station Punches of operation 5 fail premature Five station to form a valve spring retainer (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 17

20 Punch failure in a multi station Five station to form a valve spring retainer Alternating Stress Failure due to fatigue (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 20

21 Punch failure in a multi station Five station to form a valve spring retainer Alternating Stress in short time period Failure due to fatigue (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 21

22 Punch failure in a multi station Five station to form a valve spring retainer Reason for failure: material lost contact to the tooling (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 22

23 Punch failure in a multi station Five station to form a valve spring retainer High stress concentration at the point of breakage (Sig xx) (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 23

24 Punch failure in a multi station Five station to form a valve spring retainer positive tangential stress below the point of breakage (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 24

25 CPM Gesellschaft für Computeranwendung, Punch failure in a multi station Crack initialization (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Five station to form a valve spring retainer Aachen, Germany 25

26 Punch failure in a multi station Result: The change of the progression design to get the material in contact to the pin during all the solved the problem. A longer housing of the punch to avoid the upsetting in the front solved the problem. Related design rules could be revievised. Five station to form a valve spring retainer (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 26

27 Punch failure in a multi station Punch of operation 3 fails Nut making (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 27

28 Punch failure in a multi station Punch of operation 3 fails Nut making (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 28

29 Punch failure in a multi station Material flow causes severe stress distribution Nut making Result: positive stress in the punch -> punch failure (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 29

30 Punch failure in a multi station Material flow causes severe stress distribution Nut making Result: positive stress in the punch -> punch failure (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 30

31 Punch failure in extrusion Punch of operation 2 fails Cold forging extrusion (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 31

32 Punch failure in extrusion Punch of operation 2 fails Cold forging extrusion High local positive radial stress -> punch failure (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 32

33 Punch failure in extrusion Punch of operation 2 fails Cold forging extrusion Picture of a similar failure (picture from ICFG) (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 33

34 Punch failure in extrusion Punch of operation 2 changed Cold forging extrusion No high local positive radial stress after change of radius (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 34

35 Die failure in extrusion Using a hybrid approach to optimize the tool design Cold forging extrusion Die failure mainly due to overloading (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 35

36 Die failure in extrusion Using a hybrid approach to optimize the tool design Cold forging extrusion Die failure mainly due to axial stress in the insert (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 36

37 Die failure in extrusion Using a hybrid approach to optimize the tool design σ tan σ y σ tan: critical for axial cracks Cold forging extrusion σ y : critical for horizontal cracks (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 37

38 Die failure in extrusion Using a hybrid approach to optimize the tool design Horizontal splitting σ y σ y : critical for horizontal breackage splitt the insert Cold forging extrusion (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 38

39 Die failure in extrusion Using a hybrid approach to optimize the tool design σ tan σ p σ tan : critical for radial cracks pre-stress the insert Cold forging extrusion (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 39

40 Die failure in extrusion Using a hybrid approach to optimize the tool design Process material flow Cold forging extrusion (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 40

41 Die failure in extrusion Using a hybrid approach to optimize the tool design Cold forging extrusion Axial stress in the insert => split the carbide insert (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 41

42 Die failure in extrusion Using a hybrid approach to optimize the tool design Cold forging extrusion High tangential stress => improve the pre-stressing (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 42

43 Die failure in extrusion Using a hybrid approach to optimize the tool design Cold forging extrusion Simplified pre-stress analysis to optimize the design (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 43

44 Die failure in extrusion Using a hybrid approach to optimize the tool design Cold forging extrusion Simplified pre-stress analysis to optimize the design (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 44

45 Die failure in extrusion Using a hybrid approach to optimize the tool design Cold forging extrusion Checking the optimized design in FEA (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 45

46 Study of FEA applications in metal forming Conclusion A lot of tooling problems can be solved or avoided by consequent use of FEA during the design stage (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 46

47 Why to study FEA applications in metal forming es under the aspect of tool failure? Result: The prediction of tooling failure is still not a standard application of simulation. Successful applications allowed to find out guidelines to support the design engineer based on reliable simulation results. By getting experience from the studies rules could be given to enable the design engineer to foresee problems and therefore avoid costs. The design engineer is enabled to develop longer lasting tooling by using simulation instead of costly trial and error procedures. The study focused on real applications in industry and gave most practical guidelines. The research has to go on to provide more sound and reliable models on a higher level to better predict not only tool failure but tool live as well. (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 47

48 CPM Gesellschaft für Computeranwendung, Study of FEA applications in metal forming Thank you for your attention (c) Dr. Gerhard H. Arfmann, Dr. Twickler - 10th ICTP 25./ Aachen, Germany 48