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3 Fundamentals of press design

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Presses used for solid forming<br />

coining<br />

station<br />

indexing gear<br />

dial feed plate<br />

feed pocket<br />

control<br />

station<br />

Fig. 6.8.24 Feed dial plate with overload safeguard<br />

filling station<br />

overload clutch. This overload clutch is attached without backlash to<br />

the output drive shaft <strong>of</strong> the indexing drive. The connection between<br />

the drive shaft and indexed plate is formed by means <strong>of</strong> several springloaded<br />

rollers located in appropriate recesses. In case <strong>of</strong> an overload, the<br />

rollers disengage and the part <strong>of</strong> the clutch which is attached to the drive<br />

shaft can still rotate in ball bearings with respect to the blocked<br />

indexed plate. It is only possible to re-engage the clutch in a position<br />

ensuring synchronous movement with the <strong>press</strong>.<br />

The crank angle <strong>of</strong> approx. 120°, required for the indexed plate to<br />

switch around, is achieved in coining <strong>press</strong>es with a normal knucklejoint<br />

drive system (cf. Fig. 3.2.5) by means <strong>of</strong> a sufficiently dimensioned<br />

idle stroke, i. e. when there is no connection between the slide die and<br />

slide. In <strong>press</strong>es with modified knuckle-joint drive (cf. Fig. 3.2.6), the<br />

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

533

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