3 Fundamentals of press design

Component development
a component does not appear to be producible using hydroforming
technology, an attempt is made to modify the existing conditions in
such a way that the part can be produced without modifying its functional
characteristics.
The part geometry must be optimized taking into account the process
limits. Where assemblies are produced, it may under certain circumstances
be possible to group several parts into a single one or to split the
assemblies up differently. A different material can also be selected. When
making this type of modification, the question of reliability in series production
must not be neglected, as this is of decisive importance concerning
the cost effectiveness and process engineering related issues.
Configuration for series production
This stage includes the definition of a production sequence and configuration
of the necessary production lines. Consistent implementation
of the prototyping results is of particular importance here. An optimum
product is only achieved through effective interaction of theoretical
analysis and practice-oriented testing. Another aspect is the definition
of quality-relevant QA data.
Forming simulation
The Finite Element Method (FEM) has become an established feature of
metal forming technology. The objective of FEM is to replace costly and
elaborate experimental testing by fast, low-cost computer simulation.
Any practical implementation of preliminary considerations must
take into account the special features of hydroforming:
– consideration of partial strain hardening on pre-formed tubes,
– correlation between process parameters: motions and forces of the
horizontal cylinders, variation of internal pressure in time, motion of
additional die components such as hole punches and counterpressure
punches, closing movement of the die,
– functional coordination of process parameters: internal pressure, different
additional die elements such as hole punches and counterpressure
punches and axial cylinders,
– springback,
– failure criteria: buckling and bursting,
– material behavior: anisotropy and flow curve and
– description of the contact (friction) conditions.
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
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