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ComputerAided_Design_Engineering_amp_Manufactur.pdf

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FIGURE 7.11<br />

The shape of the envelope depends on the aspect ratio of the punch shape. If the aspect ratio is<br />

near the value 1, a circular envelope area is used. The envelope areas are used to stage the die operations.<br />

The relationship among the punch shape, envelope type, and mount type is illustrated in Figure 7.12.<br />

Bending Punches<br />

To simplify the problem of generating the bending punches, the bending operations required to form a<br />

feature can be classified into any of the four predefined bending configurations shown in Figure 7.13.<br />

The dimensions of the various components can be derived from the various empirical formulas provided<br />

in die design textbooks. These dimensions can also be used to derive the envelope area to represent the<br />

spatial requirement to support the bending operation during strip development.<br />

Punch Plates<br />

Relationships between component abstraction and product hierarchy.<br />

St<strong>amp</strong>ing punches and bending punches are components and subassemblies whose descriptions are<br />

directly dependent on the product features and the strip layout. Punch plates, die blocks, and strippers<br />

are some of the components whose descriptions can be deduced by reasoning about their geometrical<br />

and topological relationship with reference to the tools that they support. For ex<strong>amp</strong>le, the schema used<br />

to generate the description of a punch plate is given in Table 7.1.<br />

7.11 Rules for the Placement of Locators and Fasteners<br />

The various components of a die assembly are held together by fastening screws and placed in position<br />

by dowels. Screws and dowels must be placed such that they can effectively serve their intended purposes<br />

without interfering with the actual st<strong>amp</strong>ing tools and affecting the strength of the die. In other words,

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