Installation guide

212 Following for MX2000 version 4.0
8.1.9 - Rotating Knife Examples
A knife located on the follower axis is synchronized
with the material controlled by the master axis. The
knife is located at 12 o’clock initially and its cutting
area is located 36° on each side of 6 o’clock. Thus
the Knife must be in synchronization with the master
in the material cutting area. This system is set up
such that one revolution of the master and follower
axes is equivalent to 1 unit. The rotating knife axis is
not allowed to reverse for safety purposes.
The FOLACCDIST command value is used to
synchronize the Knife with material at startup. This
is accomplished by setting the FOLACCDIST to
twice the distance required to move the follower the
initial 144° ((144/360)*2= .8 units) to the cutting
area.
The FOLSYNCDIST command is used to control
the cutting area of the knife. Since 72° of cutting
area is required the FOLSYNCDIST is set to
(72/360) .2 units.
The FOLOFFSET command controls the moving of
the knife to the new cutting position. Thus the
FOLOFFSET = (1 – cut length)) and varies with
different cut lengths. The FOLOFFSET command
can create an advance or recede cycle depending on
the cut length.
The cut length is controlled by the distance traveled
by FOLSYNCDIST + FOLOFFSETDIST. Thus the
FOLOFFSETDIST = cut length – FOLSYNCDIST
and varies with different cut lengths.
The FOLMINRATIO command controls the
minimum speed allowed by the follower during an
Offset cycle. Since the follower axis is not allowed
to reverse direction the FOLMINRATIO must be set
to 0. This command comes into play whenever cut
length is greater than 1.
The FOLMAXRATIO command controls the
maximum speed allowed by the follower during an
Offset cycle. This command comes into play
whenever the cut length is less than 1. The
maximum attainable speed for the follower axis
limits the minimum cutting distance in this
application. Although this speed can be limited by
the FOLMAXRATIO the slope of the
acceleration/deceleration becomes steeper as the cut
distance becomes shorter.
The FOLMAXRATIO value must be set in between
the instantaneous rate and the triangular rate that is
calculated as follows:
Instantaneous rate = FOLRATIO *
((FOLOFFSET / FOLOFFSETDIST) + 1)
Triangular rate = FOLRATIO *
(((FOLOFFSET / FOLOFFSETDIST) * 2) + 1)
where :
FOLOFFSET = 1 – cut length
FOLOFFSETDIST = cut length – FOLSYNCDIST
8.1.9.1 Rotating Knife Cycle
When a FOLJOG is commanded the follower axis
ramps up to match the master velocity. The distance
traveled by the follower is .4 units (144°). It is now
in position 1 of the Rotary Knife Cycle. This is the
starting position for cutting the material.
An offset cycle is commanded and the follower and
master move .2 units in synchronization, 72° of
motion on the follower axis. The material is cut
during this portion of the cycle. It is now in position
2 of the Rotary Knife Cycle.
The offset portion of the cycle is now executed. The
master moves the FOLOFFSETDIST distance and
the follower end up at the starting position for
cutting the material (144°). It is now in position 3 of
the Rotary Knife Cycle. The material has now
moved the cut length.
This cutting cycle continues until EXIN(101)=1.
Then the program now waits for the last offset cycle
to complete. It is now in position 3 of the Rotary
Knife Cycle. A follower axis stop is now
commanded.
Both axes now travel the FOLSYNCDIST. It is now
in position 2 of the Rotary Knife Cycle.
The follower now decelerates to a stop. The distance
traveled by the follower is .4 units (144°). This puts
the knife back at 12 o’clock, which is the starting
position.
The master axis is now commanded to stop ending
the cutting cycle.