Robot Cell Product Entrance Guarding

[Lynx777]

Hello All,

I'm looking for some opinions and Ideas for guarding the product entrance of a palletizing robot cell.

Please see the attached image.

1. The cell fencing comes up to within a couple of inches either side of a conveyor.
2. The conveyor is approximately 30 inches wide.
3. There is no guarding above the conveyor.
4. The rolled product can be up to 36 inches in diameter and either 24 or 48 inches long.

The only way a person can get through the opening above the conveyor is by riding the conveyor through the opening. My safety manager is insisting that I come up with a way to stop a person from doing that.

So my questions are.....
1. Is this a legitimate concern or is my safety manager being paranoid?
2. If this is a legitimate concern what would be a good way to guard the opening?

 

[Steve Bailey]

It's the Safety Manager's job to identify hazards. If (s)he says it needs to be addressed, then it needs to be addressed.
Keyence makes a product that scans the opening and can be programmed for an allowable profile to pass.
https://www.keyence.com/landing/saf...FfDPTRqLSi81yBHosFNcLyx2llmRTohUaAu_uEALw_wcB

 

[Lynx777]

Thanks, I'll look into that.

I've used laser area scanners before but I didn't know that they could recognize the profile of an object now. The ones I've used had a fixed area and that was it.

 

[joseph_e2]

Light curtains generally allow "muting" for product to pass through...but...I've only done it with product leaving the cell where the muting sensors are inside the safety zone. Basically, the sensors have to be blocked and cleared in the right sequence and timing in conjunction with the light curtain being blocked and cleared. Depending on what you're using for a safety controller, it may be possible to use a muting sequence that's specific enough that it's "hard enough" for a human to successfully mute it to be safe. If they're just riding the conveyor, though, that will be difficult.


Steve Bailey: I've used those scanners but not a feature where you can have it verify that it's product and not a person. I'll have to look at that. It's a very interesting feature that I would seriously consider using if we needed to mute on the way into the cell.

 

[Lynx777]

Light curtains generally allow "muting" for product to pass through...but...I've only done it with product leaving the cell where the muting sensors are inside the safety zone. Basically, the sensors have to be blocked and cleared in the right sequence and timing in conjunction with the light curtain being blocked and cleared. Depending on what you're using for a safety controller, it may be possible to use a muting sequence that's specific enough that it's "hard enough" for a human to successfully mute it to be safe. If they're just riding the conveyor, though, that will be difficult.

The product exit for this cell currently uses a muted light curtain and exactly as you said using one on the entrance would probably not work.

 

[I_Automation]

What you need to detect isn't "something" going through, it's "something capacitive" like a body.


A prison was built in the area and they made a big PR release that the fence around it had a cable run all the way around that was basically a capacitance sensor. If a person got within a few feet of the cable the capaciance in the area changed and it triggered.


Here's an abstract of a book on them.


EDIT: I think some highway weigh stations have something similar to detect if there are people in the trailers


Here's an article about passive WiFi to detect humans (sorry, subscription required to read full article, but there should be others about the field)


EDIT2: If anyone is thinking no adult would be that big of an idiot to jump on on the conveyor while it is running - I know a guy that worked as a dishwasher in a large kitchen (actually the leader of the department) and he wrapped himself in rubber aprons to see what a ride on the conveyor through the dishwasher would be like, pumps and blowers running. Yes, he regretted ever doing it - but he did it.

 

[Lynx777]

Thanks I_Automation,

Those ideas look very interesting! I will check them out.

 

[Jeev]

The relevant Type A/B/C standards for the US will contain all the answers you are after - I'm not sure if these are EN/ISO for you guys, but they are AS4024 for us here in Aus (And sometimes EN/ISO for things not yet adopted like EN619). They dictate the requirements for things like Guarding, ESPE's, Industrial Robots, and Ergonomics. I am familiar with AS4024, and our standards, regulations and legislation, but I am not familiar with yours. You would need to look into this to ensure your site is compliant with the relevant requirements.