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3 Fundamentals of press design

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Die <strong>design</strong><br />

Fig. 6.7.5 Shearing die with wedge-action pusher, holding sleeve hydraulically clamped<br />

6.7.2 Die and punch <strong>design</strong><br />

Dies are subjected to high degrees <strong>of</strong> internal <strong>press</strong>ure which can quickly<br />

lead to die failure using single ring extrusion containers manufactured<br />

with die steels available today. The extremely high stresses, present<br />

on the internal die wall <strong>of</strong> the extrusion container (cf. Sect. 6.5.1)<br />

can be reduced by pre-stressing (shrink-fit) the container with one or<br />

more shrink rings. Punches are subjected initially to <strong>press</strong>ure and then<br />

additionally, depending on the process, to bending stress as a result <strong>of</strong><br />

<strong>of</strong>f-center loads. Less frequently, the possibility <strong>of</strong> punch buckling must<br />

be taken into consideration. The calculation methods outlined here for<br />

dies and punches are described in detail in VDI Guidelines 3176, VDI<br />

3186 and ICFG Doc. No. 5/82.<br />

Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998<br />

491

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