Rapid-Air SERVO FEED GAG FEED: 950 SERIES - Manual (Page 18)

17
FEED ARC
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 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 calculation 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 accelleration/
decelleration rate. The smaller the feed arc the higher the accelleration/decelleration rate
and the fewer strokes per minute for a given feed length.