7. Conclusion

Numerical simulation therefore appears to be an effective tool for optimizing forming conditions in order to obtain a product with the most even thickness possible (or as close as possible to specifications).

The tricky problems lie at several levels:

• knowledge of initial conditions (initial sheet and parison thickness distribution, temperature distribution). This requires integrating previous heating and extrusion operations into the modeling (with the problem of predicting parison swelling at the die exit);

• definition of appropriate behavior laws and determination of their coefficients.

Eventually, modeling should make it possible to go further in at least two directions:

• optimize the initial temperature...