Rapid-Air SERVO FEED: 100C, 100D series - Manual (Page 13)

To explain how the “feed arc” is
related to the servo feed calculation,
we must first explain what the feed
arc is in relation to a press.
The press has a die that has two
halves. The lower half is stationary
and the top half is moveable in an up
and down motion which is one cycle
from the full open to the full closed to
the full open again. The component
that makes all of this happen is named
“crankshaft”. The crankshaft makes
a 360 degree revolution for one cycle
of the die from open to close to open
again. When the die is fully open, the
crankshaft would be at “0” degree
position. When the die is fully closed
the crankshaft is at 180 degrees or
one-half of a revolution.
We ask that a switch be set at 270
degrees to activate the feed because
Feed Arc Relationship
at this position, the die is completely
clear of the material. This is also a
good starting point to explain the
“feed arc” portion of the auto
calculation in the Rapid Air program.
If the feed input switch was tripped
at 270 degrees of the total revolution
of the crankshaft and the arc calcula-
tion was 180 degrees then the servo
feed would complete it’s feed by 90
degrees of the press cycle or 180
degrees past the 270 degree mark.
The feed arc could be set at 90
degrees so the feed cycle would be
complete by 360 degrees or when the
press was at the top of the stroke.
The feed arc could be set at 270
degrees so the feed cycle would be
complete when the press was at 180
degrees. This example would not
work if the feed cycle started at
270 degrees as the feed would still be
trying to move the material when the
die was closed or together. To use a
270 degree feed arc the feed would
have to start at 230 degrees or 240
degrees to be finished moving the
material before the die was closed
or together. This example could not
be possible if the die had pilot pins
installed in it for precise locating of
the stamped part. The cam switch
drawing in the back of the manual
will help you visualize the above feed
arc explanation.
In essence, the larger the feed arc
number up to 270 degrees, the lower
the acceleration/deceleration rate.
The smaller the feed arc the higher
the acceleration/deceleration rate
and the fewer strokes per minute for
a given feed length.
FEED ARC