ComputerAided_Design_Engineering_amp_Manufactur.pdf

7.1 Introduction
Nowadays, metal stampings are used in almost every mass-produced product. This is because metal
stamping is a flexible production process that can be used to produce complex, accurate, strong, and
durable articles cheaply and quickly. In metal stamping, successful products are the results of good
product and tool design. Modern CAD/CAM technology and new ideas in design and construction of
tools, coupled with increased speed and rigidity of the presses, have contributed to the continuous use
of metal stamping production processes to manufacture increasingly more sophisticated products.
Progressive dies are high precision tools used for producing metal stampings. In a progressive die, the
workpieces are advanced from one station to another. At each station, one or more die operations, such
as piercing, notching, blanking, lancing, shaving, drawing, extruding, embossing, coining, blanking, and
forming are performed on the sheet metal strip. The result is a finished component deposited on the
stack at every stroke of the press.
7.2 Planning, Design, and Manufacture of Progressive Dies
The design and manufacture of a progressive die begin with the task of planning for the sequence of die
operations that need to be performed to manufacture a part. This planning process is called the strip
design. This is a very important process as it affects the optimum operation of a progressive die and has
a direct bearing on the cost of fabricating the die and on the cost of metal stampings produced. This
planning process includes selecting the best layout of the flat pattern to optimize stock material
usage(nesting), selecting and ordering a combination of punches that will stamp out the required part,
selecting piloting holes to guide the strip as it progresses along the die, and ensuring that the workpieces
are attached to the strip by means of a carrier web until the final cut off at the last station.
Based on the sequence of operations decided during the strip design, the die is designed. The die is
designed such that the workpieces can be accurately fed and located at each station. It has to cater to the
removal of slugs, ejection and stripping of parts, precision guidance for its punches, ease of replacement
of punches for sharpening or replacement, safety of operation, and robustness of the die to withstand
high speed cyclic stamping forces. The die is constructed by assembling together die components such
as punches, punch plate, die block, pilots, strippers, stock guides, guide bushings, guide posts, and die
sets located by dowel pins and held together by fastening screws.
There are two categories of components in a progressive die: (1) standard die components such as
standard punches, pilots, guide bushings, guide posts, dowel pins, fastening screws, and die sets which
can be purchased from die components manufacturers; and (2) non-standard components such as punch
plate, die blocks and non-standard punches that need to be custom-made in the tool room. The manufacturing
plan for fabricating the non-standard components will be developed first. This includes the
selection of cost-effective setups, selection of fixturing requirements, selection of machine and cutting
tools, generation of NC tool-paths, and heat-treatment processes. Thereafter these components are
machined and treated. Finally, all the components are assembled together to form the progressive die.
7.3 Factors Influencing the Use of Intelligent Techniques for the
Planning, Design, and Manufacture of Progressive Dies
The processes involved in the planning, design, and manufacture of a progressive die are shown in Figure 7.1.
They involve many inter-related tasks requiring the support of multi-disciplinary engineering and tooling
skills based on theories and principles, design codes, heuristic procedures, personal expertise, and experience.
There is a wide variety of research on the use of intelligent techniques in solving design problems.
It is essential to apply the most appropriate artificial intelligence techniques to handle these design and
tool-making tasks when developing a computer-aided, integrated planning, design, and manufacturing