Problem with muting light barrier

Plc_User · Sep 17, 2011

We have a conveyor system for boxpallets with a safety zone protected by muted light barriers (Sick M4000 A/P) connected to a Pilz Multi safety controller.
Cross muting is being used.
In a previous slightly different system it worked fine,
but here sometimes the lightcurtain is tripped when a box is moved through the lightbarrier (although not al the time).
The muting sensors are about 25 cm before and after the lightbarrier. The muting sensors use mirrors to send back the signal.
I must say the box is not moved completely in the center between the light barrier sender/receiver and mirror.
What could I do to make the transfer of the boxes more reliable?
Place the muting sensors closer or further from the light barrier? Should I make sure that the center of the transported boxes moves through the crosspoint of the two muting beams or doesn't it matter?
Transfer of boxes is in both directions, should the crosspoint of the muting beams be before, in or after the lightcurtain?.
I already set the simultanity of the muting to a level of 3 seconds, but it didn't help.

Thanks

OkiePC · Sep 17, 2011

Is the trailing edge of the pallet plumb?

Does the most forward leading edge always break the muting cross point as centered as possible?

In other words, with a top view, like a horserace photo finish, you want the edges of the pallet to be flat and square but also centered between the muting transmitter and receiver. I think that you should consult the appropriate manual for use with a mirror for ideal side to side geometry.

But generally, from the front view, you want the nose of the load to break the muting sensor first, and the trailing edge can be critical too with the latest safety standards these specific light curtains seem to all be using.

I am using smartscan pallet conveyor robot cell exit barriers and their newest model with good industrial connectors has a fixed 2 second trailing edge timer. In other words, as soon as the trailing edge of the load clears the muting sensor, the entire vertical curtain must be completely clear within 2 seconds...no adjustment...no way around this feature in mine except to exit faster (luckily these were already on VFDs).

Plc_User · Sep 18, 2011

OkiePC said:
Is the trailing edge of the pallet plumb?

Does the most forward leading edge always break the muting cross point as centered as possible?

In other words, with a top view, like a horserace photo finish, you want the edges of the pallet to be flat and square but also centered between the muting transmitter and receiver. I think that you should consult the appropriate manual for use with a mirror for ideal side to side geometry.

But generally, from the front view, you want the nose of the load to break the muting sensor first, and the trailing edge can be critical too with the latest safety standards these specific light curtains seem to all be using.

I am using smartscan pallet conveyor robot cell exit barriers and their newest model with good industrial connectors has a fixed 2 second trailing edge timer. In other words, as soon as the trailing edge of the load clears the muting sensor, the entire vertical curtain must be completely clear within 2 seconds...no adjustment...no way around this feature in mine except to exit faster (luckily these were already on VFDs).

Thanks so far.
The conveyors are direct online starters, no vfd.
The position of the lightbarrier itself and the boxes cannot be changed due to construction. As I told, if you have a topview the pallet, the pallet is not in the center between both parts of the light barrier.
The only thing I could change is alligning the crossed muting cells in that way that the crosspoint of both muting beams is in the middle of the box. Also I could place the muting fotocels closer to or further from the light barrier.
Would these changes solve the problem, to your experiences?

Thanks

kiwi sparky · Sep 18, 2011

Where is the muting configured? in the Pilz or is the cutain conected to a SICK UE403 muting module?
Either way will have configurable timers that can be modified as long as you know what you are doing and your changes dont impact on the safety of the system
Cross muting light curtains require symetrical loads and the loads to be in the centre of the cross to operate repeatably and reliably

Plc_User · Sep 18, 2011

Thanks Kiwi sparky.
The muting is in the Pilz Multi.
In the drawing there is just one travel direction, but in my case the
box can move in and out the safety zone.
Should in my case the intersection point be in the beam of the light barrier?

kiwi sparky · Sep 18, 2011

No, intersection should always be on hazard side. The setup in my picture can work in both directions. You would set up muting to turn of when Light curtain was clear, rather than when muting photo eyes were clear. Load symertry and centering is much more important. Please post dimensions/drawing of your setup and pilz program if you are allowed

Plc_User · Sep 23, 2011

I arranged my muting photocells and my mirrors in that way that the crossing point of the two lightbeams is now in the center of the box,
and it seemed reliable.

iant · Sep 23, 2011

Just make sure that the Light curtain can NOT be muted by a person walking or Falling through the mute beams now.
You may have created a hazard that needs to be checked.

Problem with muting light barrier

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iant

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