Example: Printing Of Cardboard Boxes With Marker Correction - Danfoss VLT5000 SyncPos Operating Instructions Manual

■ ■ ■ ■ ■ Example: Printing of cardboard boxes with
Marker Correction
If the boxes are not always transported at the
exact same distance from each other, markers will
be required that can recognize a box and correct
the synchronization.
The following section describes how you can adapt
the curve of the previous example to this appli-
cation.
Again, a roller is supposed to stamp an inscription
with a length of 10 cm on cardboard boxes. A
maximum of 60 boxes are transported on the con-
veyor belt per minute. During the printing opera-
tion, both the stamping roller and the box must run
in sync.
How to edit a curve for Marker Synchronization
1. Steps 1 to 9 are the same as in the previous
example.
10. Define the point pairs for the engaging and
disengaging in the index card → "START
STOP POINTS". We make the assumption that
engaging takes place at the beginning of the
box and disengaging is to take place until the
end of the box.
11. In the index card → "CURVE DATA", deter-
mine the position in which the roller should stop
if no other Slave Stop Position is defined in the
program.
The roller always needs to return to the position
0 degrees:
→ "SLAVE STOP POSITION" = 0
42
Programmable SyncPos motion controller
12. The photoelectric beam (external marker) has a
distance of 237.5 mm from the processing point
(= stamp touches the cardboard box) and
detects the beginning of the box (corresponding
to master position 1000). The marker distance is
therefore 2375. Enter this value in the index card
→ "SYNCHRONIZATION" and define the permit-
ted tolerance for the appearance of the markers
and the external marker type = 2 for the master:
Master Marker
Enter the master position in the index card →
"CURVE DATA":
13. Take a look at the curve profile in order to de-
termine when the correction of the synchroniza-
Stamping roller = Slave tion may begin at the earliest and when it must
be finished. The vertical green line indicates the
Conveyor belt = Master
master position where the marker is recognized,
Master positions (1/100 mm)
the light green area shows the tolerance window
for the appearance of the master marker.
(See PC-Software for colour.)
At the earliest, the correction may begin when
the printing of a box has been completed,
since any change of velocity during the prin-
ting process would damage the box. The cor-
rection must be finished completely when the
next box reaches the processing point. In this
example, the master positions at the end and
beginning of a box are quite suitable:
Enter the values in the index card → "CURVE
DATA"; the depiction of the area is shaded in
blue in the curve profile.
Distance SYNCMPULSM (58) = 2375
Tolerance SYNCMWINM (68) = 200
Typ SYNCTYPM (60)
Master-Marker-Position = 1000
Correction Start = 3000
Correction End = 1000
MG. 1 0.J8.02 – VLT is a registered Danfoss trade mark
= 2