AutoForm News
May 31, 2004:
4D-Process-Layout for Sheet Metal Parts
AutoForm’s software for 4D-Process-Layout is ‘the
first commercially available solution to generate, validate and
optimise the entire sheet metal forming process’.
The September/October 2001 issue of ISMR featured an article
about a new software for rapid die face design and tooling optimisation
from AutoForm Engineering. An update in the May/June 2002 issue
reported on the software’s 100th customer, and the benefits
and cost savings realized at BMW and DaimlerChrysler Germany.
The software is now in use with the twenty largest automobile
producers and at over 200 tooling and stamping suppliers.
This article previews two important technical innovations in
the latest version of the software – 3D-Die-Layout and
4D-Process-Layout – which are of particular interest to
process planners and tool designers.
Figure 1: The combination of the 3D-Die-Layout and the process simulation
leads to
the new concept of the 4D-Process-Layout
Getting the right data
To plan the entire stamping process and associated tooling,
and to generate the process layout for all required forming operations,
accurate and reliable information is needed. Typical questions
that process planners and tool designers need to answer include:
What is the best drawing direction? Will splits occur after restrike?
What press forces are required? Are there any critical trim angles?
Will all of the stamped parts be produced within tolerance, all
of the time?
The conventional approach to generate a process layout –
converting a flat blank into a 3D part geometry via several operations
(e.g. first draw, second draw, trim, restrike, flange) – is
typically CAD based, involving 2D sectional design. This procedure
is relatively unstructured, with the results of the process
layout depending upon the experience of the tool designer.
Furthermore, to generate 3D surfaces manually is not only time-consuming,
but relevant practical experience may not even exist for new
materials such as high-strength steels, which are increasingly
being used to reduce vehicle weight.
The resulting 3D active surfaces are then used for tryout simulations
of the forming process, and based on the simulations, the surfaces
must be modified for additional tryouts until a satisfactory
process is achieved. However, planners and designers typically
do not have the time to make many surface modifications, to evaluate
alternate process layouts or to optimise them. Therefore, the
surface data used for the tryout simulations – and for
subsequent milling of the tools – are not the best, and
quality and reliability problems occur during production.
Technological innovations
AutoForm’s new software addresses these problems by enabling
early validation of the entire sheet metal forming process, combined
with simulation of all the forming operations (pre-form, draw,
trim, restrike, flange) and springback.
Specifically, the software’s innovative concepts allow
process planners and designers to directly generate 3D-Die-Layouts
for all the stamping operations (including secondary operations)
and directly validate the 3D-Die-Layouts through process simulation.
The 3D-Die-Layout integrated with the process simulation, which
describes the movement of the tools and their effect on the formed
sheet over time, is called 4D-Process-Layout. The 4D-Process-Layout
provides much more informative feedback and is more reliable
than conventional 2D-Process- Layouts, yet it requires less time.
With its focus on the entire process including springback, the
quality of the stamped parts and the robustness of the stamping
process are increased and overall development time is reduced.
3D-Die-Layout
Several new ideas form the basis of the 3D-Die-Layout. First,
the definition of 3D active surfaces for all operations is essentially
based on the 3D part geometry. Secondly, an inverse approach
is used to generate the surfaces. Finally, the 3D-Die- Layout
is directly linked to process simulation, which is in fact the
principle behind the 4D-Process- Layout concept.
Figure 2: Reverse part development (left column)
and corresponding die layout (right column)
The 3D-Die-Layout starts with the complete 3D part geometry,
and proceeds backwards to the flat blank, operation by operation,
as shown in the left column of Figure 2. An important advantage
of this approach is that all operations in the entire process
layout are ‘associatively linked’. This means that
the effects of modifications to intermediate forming operations
and even to the final part geometry are automatically reflected
in the tooling surface data of all preceding operations. As a
result, the software is well suited to the tasks of process planners
and tool designers. Quickly and easily, they can define the entire
stamping process and make process modifications, and also consider
and evaluate different process layouts in order to find the best
ones.
4D-Process-Layout
The 4D-Process-Layout includes the tryout simulation of the
3D-Die-Layout. It follows the production workflow, as shown in
the right column of Figure 2. Each modification from one geometry
stage to the next (see left column) corresponds to a forming
operation. The required tools and the corresponding process are
automatically created by duplicating and trimming the 3D active
surfaces as well as by moving the tools in their working direction
(right column). After the tool geometries have been determined,
the initial blank outline is defined in the last modification
- developing the 3D active surfaces to a flat blank.
AutoForm’s software for 4D-Process-Layout is the first
commercially available solution to generate, validate and optimise
the entire sheet metal forming process.
Many alternative process layouts can be evaluated in less than
one day. Process planners and tool designers thus have all the
information they need to define a robust production process for
sheet metal parts – and process planning can reach a new
level of efficiency and reliability.
"4D layouts for sheet metal parts"
[pdf - 127 KB]
in: International Sheet Metal Review Volume 6, No. 3, May/June 2004
Reproduced with permission,
copyright 2004 by Mack Brooks Publishing Ltd.
www.sheetmetalplus.com
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