QForm can show die stress on the surface of the die and internally in both 2D and 3D tool simulations.
A tool simulation can be run where the user can click buttons to see the following properties in the tool:
- Effective stress and strain
- Mean stress
- Radial stress and strain
- Axial stress and strain
- Hoop stress and strain
- Shearing stress and strain
- Volumetric strain
- Distortion due to forming load
- Radial and axial displacement
- Die wear factor
It is useful to see the effective stress values in your tools to be sure that you are within the yield strength of your tool steel. If you exceed the yield strength of your die steel you will encounter localized plastic deformation in those areas of your dies that will quickly lead to failure. Elevated values of effective stress should be avoided.
It is very easy to see the effects of a shrink ring on both 2D and 3D tool simulations.
The dimensions and fit of the shrink ring can be easily adjusted to find the optimal values.
Effective stress without shrink fitting
Effective stress with shrink fitting
Example of die stress simulation benefits
In the following example a forge die for a gear with finish-forged teeth for a PTO Application was cracking after around 400 parts. Improvement was needed for production quantities.
Close up of die crack
Tool simulation showed local elevated levels of stress where the die was cracking
The problem is solved by separating the die into two parts with the use of an insert so that the die can move freely eliminating the high stress in this area.