3 Fundamentals of press design

306 Sheet metal forming and blanking
In the case of automatic part discharge, the stroke of the press slide lies
between 150 and 300 mm due to the long discharge period. An
adjustable slide stroke offers the advantage that progressive dies with a
small stroke of for example 40 mm can be used to optimum effect (cf.
Fig. 3.2.13). Mechanical discharge devices which are either directly driven
or controlled by the press are generally used.
The parts are ejected when the press is at its top dead center and they
are collected bydischarge plates,which deposit them outside the press on
a magnetic belt, as illustrated in Fig. 4.6.18 for a finished segment.
Depending on the part size, this method limits the stroking rate of the
press to between 20 and 60 parts per minute. This requires a slide stroke
of 150 to 300 mm. Due to the long slide stroke required, a part discharge
method has been developed in which the punched parts are collected
and pushed out by two raised lugs in the scrap web (Fig. 4.6.19). The dies
can be operated with a substantially smaller slide stroke of 70 mm, so
finishedsegmentblank
rollerfeed
coilstock
complete blanking die
scrapweb
dischargebelt
forunfinished
segments
unfinishedsegment
dischargeplate
scrap chute
magneticbeltfor
finishedparts
liftingtable
scrap con eyorbelt
Fig. 4.6.18 Discharge plate and destacking magnetic belt for an unfinished segment
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998