Analysis of Tooling failures using FEA

Transcription

1 - industrial applications G. H. Arfmann, M. Twickler*) *)G. H. Arfmann and M. Twickler are joint managing directors of CPM GmbH, Germany The presentation shows industrial applications of FEA. The aim of using FEA is to enable the design engineer to develop long lasting tooling by using simulation instead of costly trial and error procedures. To show the ability of FEA examples were chosen in which the engineer used FEA to solve existing tooling problems. By getting experience from these the design engineer is able to foresee such problems in future and therefore avoid a lot of costs. CPM GmbH 1

2 Die failure in a multi station Die of operation 4 fails premature CPM GmbH 2

3 Initial tool design in operation 4 30 SENAFOR 14a International Forging Conference forming in operation 4 CPM GmbH 3

4 Initial design of the die in operation 4 (carbide pre stressed with a single ring) Pressure on the carbide CPM GmbH 4

5 Positive axial stress in the carbide => tool failure new design of the die in operation 4 (carbide pre stressed with two rings) CPM GmbH 5

6 Still positive axial stress in the carbide => tool failure (the carbide has to be split as well due to the positive axial stress further down) new design of the die in operation 4 (carbide split pre stressed with two rings) CPM GmbH 6

7 CPM GmbH 30 SENAFOR 14a International Forging Conference Still positive axial stress in the carbide => tool failure September 2010 Senafor Porto Alegre 30 SENAFOR 14a International Forging Conference September 2010 CPM GmbH Senafor Porto Alegre 7

8 new design of the die in operation 4 (Disc made of ASP 30 carbide pre stressed with two rings) corrected new design of the die in operation 4 (Disc made of ASP 30 carbide and disk pre stressed with two rings) CPM GmbH 8

9 final design of the die in operation 4 (Disc made of ASP 30 carbide and disk pre stressed with two rings) Stress is compressive - tool life increased from to pieces CPM GmbH 9

10 Punch failure in a multi station Punches of operation 5 fail premature Punch failure in a multi station Punches of operation 5 fail premature CPM GmbH 10

11 Punch failure in a multi station Punches of operation 5 fail premature Alternating Stress Failure due to fatigue CPM GmbH 11

12 Stress (N/mm²) Time (sec) Alternating Stress in short time period Failure due to fatigue Reason for failure: material loose contact to the tooling CPM GmbH 12

13 High stress concentration at the point of breakage (Sig xx) positive tangential stress below the point of breakage CPM GmbH 13

14 CPM GmbH 30 SENAFOR 14a International Forging Conference Crack initialization September 2010 Senafor Porto Alegre 30 SENAFOR 14a International Forging Conference Punch failure in a multi station Nut making Punch of operation 3 fails September 2010 CPM GmbH Senafor Porto Alegre 14

15 Punch of operation 3 fails Nut making Material flow causes severe stress distribution Nut making Result: positive stress in the punch -> punch failure CPM GmbH 15

16 Material flow causes severe stress distribution Nut making Result: positive stress in the punch -> punch failure Punch failure in extrusion Punch of operation 2 fails Cold forging CPM GmbH 16

17 Punch of operation 2 fails Cold forging High local positive radial stress -> punch failure Punch of operation 2 fails Cold forging Picture of a similar failure (picture from ICFG) CPM GmbH 17

18 Punch of operation 2 changed Cold forging No high local positive radial stress after change of radius Conclusion A lot of tooling problems can be solved or avoided by consequent use of FEA during the design stage CPM GmbH 18

19 Thank you for your attention CPM GmbH 19