CHAPTER 4: ELECTRICS 4-21
ALPHA ST320 S2
4.4. Signals from the bar feed system to the lathe
a) 24V DC power supply
All the signals from the bar feed system were powered by the 24V DC from the lathe. When the
corresponding relay energized at the bar feed system, the 24V DC travel through corresponding contact
at bar feed system relay and return to lathe PLC. The lathe PLC hence receives bar feed system signals.
b) R1 alarm relay
When the bar feed system is in normal operation, the R1 relay is energized and the signal to the lathe is
ON. In the event of an alarm or break in the emergency stop loop, this relay is de-energized and the
signal to the lathe is OFF.
For safety reason, this signal should bring to a stop of the axis movements of the lathe as well as the
rotation of the spindle.
c) R2 START signal relay
Relay R2 confirms the action of general part feed out or/and a new bar stock loading is finished. Refer to
service parameter MODE 15 and 16 for related set up.
d) R3 BAR END (end of bar) relay
When the pusher reaches BAR END position during feed out process, relay R3 energizes. This signal is
used to indicate that the rest bar stock length is not long enough to machine a complete part according to
part length set at P02
.
In case the part needs multiple chuck openings. This position must set according to the longest length of
those different machining sections.
Refer to operation parameter P02, P04 and service parameter MODE 14 for further information.
e) R4 bar feed system in auto relay
This signal is present as soon as the bar feed system is switched into automatic mode (AUTO READY +
AUTO START)
f) R5 INCHING relay
This relay energizes under circumstances below presents during bar change process:
− the short pusher is moving forward for placing the bar stock at FIRST FEED position
− the pusher is moving forward for placing the bar stock at TOP CUT position after insertion
For bar stocks without proper preparation or is profiled, it might struggle to enter the chuck. Generally the
spindle slowly rotates when the new bar stock is passing through. For lathes that the spindle is not
allowed to rotate when chuck is open, this signal acts as an external order to turn the spindle.
Refer to service parameter MODE 25 for more information.
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