3 Fundamentals of press design

504 Solid forming (Forging)
daylight
slide
oil cushion annular piston
bed
neutral plate
for the closing
system
counterpunch
cushion pins
neutral plate
for the closing
system
Fig. 6.7.10 Multiple-station die set with hydraulic closing systems
at the top and bottom of each station
wards into the press bed via a counterpunch are absorbed centrally.
This determines the minimum inside diameter of the annular piston.
As a guideline, the closing force can be estimated to be 0.6 to 0.9 times
the punch load. The required closing force depends on whether a completely
closed (or trapped) die set is being used or forging takes place
through extrusion shoulders into a free space. In the case of completely
closed (trapped) die sets, the closing system also serves to apply an
axial pre-stress on the parting line of the dies, that are subjected to high
loads.
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998