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ComputerAided_Design_Engineering_amp_Manufactur.pdf

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FIGURE 7.9<br />

Symbolic relationship between entities in the CAD data base and the knowledge base.<br />

screws and dowels as specified by the respective rules may conflict with the predefined positions<br />

of the punches and the pilots, as well as the rules on distance between holes and distance between<br />

holes and edge of plate. As the latter takes precedence, rules are introduced to shift the offending<br />

screws or dowels.<br />

3. The knowledge base is supported by a library of standard catalogue die components, each identified<br />

by a part identification. The parametric dimensions of these standard components are retrieved<br />

from a library of data files and stored as multivalued slots in the respective objects in the component<br />

abstraction.<br />

7.10 Schemas for the Description of Some Die Components<br />

Piercing, Notching, and Blanking Punches<br />

Piercing, notching or blanking punches, P, can be described by the following function:<br />

P �<br />

f(S,M,L)<br />

where S � punch shape<br />

M�<br />

mounting method<br />

L � length of the punch<br />

The derivation of the punch shape was described earlier. The length of the punch is a function of the<br />

shut height and various components’ thickness, which affects the vertical height of the die. To help<br />

simplify the problem, only three mounting methods are adopted. The rules for the selection of mounting<br />

method are

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