ComputerAided_Design_Engineering_amp_Manufactur.pdf

system for progressive dies. The following factors are to be considered when developing an intelligent
system to assist the die maker:
• Die making is an iterative, feedback process. The system should allow the user to generate initial
trial designs quickly and the resulting information should be used to direct the search for a solution.
Each trial design (iteration) adds information (i.e., provides feedback to the user) thus progressively
moving towards the final solution. Here, the role of the computer should be restricted to
what it can do best, i.e., evaluation of functions, execution of procedures, search data, and
presentation of information to the designer in an appropriate form. During the iteration process,
the die maker should be given adequate control over the computer in order to exercise his personal
experience and judgment to handle ambiguity, redefine design objectives, relax constraints, exercise
common sense, apply knowledge from domains not programmed into the computer, and exercise
his creativity.
• Die making is a complex process and should be structured into smaller, inter-related, manageable
subtasks. The system should be able to control the planning and design process so as to allow the
user to combine a series of sub-optimal solutions at each of the subtasks into the most preferred
solution. While a computer can be programmed to achieve an optimum solution for some of the die
making tasks, the progressive die produced by integrating the optimum solutions from these subtasks
is not always the best solution. For example, the nested arrangement that provides the best material
utilization may not necessarily be the preferred solution when the additional constraint of accommodating
the indirect piloting holes is considered. In another case, a strip layout that requires the
least number of stations may not necessarily be the preferred solution as it may be difficult or
impossible to accommodate all the tools within the limited die area, or the resulting die may be
structurally too weak or difficult to maintain.
• The die making process involves the processing and manipulation of different types of data and
knowledge by the computer. First, interactive graphical aids need to be provided for the user to
create, view, and manipulate the plans, designs, and engineering models. Second, a knowledgebased
system is required to provide the framework to store and manipulate the objects and rules
associated with die making. Third, numerical routines are needed to process, transform and
manipulate the geometrical data to support the various spatial planning, pattern processing, and
recognition tasks. Finally, a solid modeler is required to provide the 3-D representation of the
progressive die.
• Die design is the synthesis of a semi-custom product. It involves the synthesis of the progressive
die (engineering model) from the strip layout (plan model) by selecting standard tooling components
and generating non-standard tooling components, modifying them, and then assembling
these components together.
• The die maker usually builds a progressive die by adapting old designs to meet the manufacturing
requirements of the new product. In other words, the die is not always generated from first
principles.
We will now examine how the various intelligent techniques can be applied to develop a computer
aid for the planning, design, and manufacture of progressive dies.
7.4 Metal-Forming Features to Formalize the Description
of the Product
Machining features have been used to formalize the description of a workpiece when developing computeraided
process planning and automated fixturing systems for Computer Numerical Control (CNC)
machining. Similarly, metal-forming features can be used as a language to formalize the description of
metal stampings in a knowledge-based system.