3 Fundamentals of press design

536 Solid forming (Forging)
Figure 6.8.26 indicates the individual phases required for the piercing
process:
– The upset coin blank is centered in the piercing station by the feed
insert. The slide is positioned in the bottom dead center.
– The slide moves upwards, the coin blank is held between the female
piercing die and the spring-mounted stripper.
– The coin blank is inserted in the holding collar and pressed against
the fixed piercing punch.
– At the top dead center, the piercing process is completed, the scrap
web is pushed through the piercing punch into the scrap hole of the
female piercing die.
– On the return stroke of the slide, the spring-mounted stripper pushes
the pierced coin blank out of the holding collar back into the feed
insert. The pierced coin blank is discharged by the indexed dial feed
plate, while a new upset unpierced coin blank is fed for the next
cycle.
ejector
piercing punch
spring-loaded
stripper
down stroke,
blank feed
piercing die
holding collar
feeder insert
contact with
ejector
Fig. 6.8.26 Piercing sequence
contact with
piercing punch
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
up stroke,
blank pierced
down stroke,
discharge of
pierced blank