3 Fundamentals of press design

Principles of die manufacture
produced. The information given in the part drawing includes: part
identification, part numbering, sheet metal thickness, sheet metal quality,
tolerances of the finished part etc. (cf. Fig. 4.7.17).
To avoid the production of physical models (master patterns), the
CAD data should describe the geometry of the part completely by means
of line, surface or volume models. As a general rule, high quality surface
data with a completely filleted and closed surface geometry must be
made available to all the participants in a project as early as possible.
Process plan and draw development
The process plan, which means the operational sequence to be followed
in the production of the sheet metal component, is developed from the
data record of the finished part (cf. Fig. 4.1.1). Already at this point in
time, various boundary conditions must be taken into account: the
sheet metal material, the press to be used, transfer of the parts into the
press, the transportation of scrap materials, the undercuts as well as the
sliding pin installations and their adjustment.
The draw development, i.e. the computer aided design and layout of
the blank holder area of the part in the first forming stage – if need be
also the second stage –, requires a process planner with considerable
experience (Fig.4.1.8). In order to recognize and avoid problems in
areas which are difficult to draw, it is necessary to manufacture a physical
analysis model of the draw development. With this model, the
forming conditions of the drawn part can be reviewed and final modifications
introduced, which are eventually incorporated into the data
record (Fig.4.1.9).
This process is being replaced to some extent by intelligent simulation
methods, through which the potential defects of the formed component
can be predicted and analysed interactively on the computer display.
Die design
After release of the process plan and draw development and the press,
the design of the die can be started. As a rule, at this stage, the standards
and manufacturing specifications required by the client must be considered.
Thus, it is possible to obtain a unified die design and to consider
the particular requests of the customer related to warehousing of standard,
replacement and wear parts. Many dies need to be designed so that
they can be installed in different types of presses. Dies are frequently
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