Hydraulic Press and Safety

[glaverty]

Thanks for the replies everybody, I really appreciate the input.

Eric,

On your jam bar, is that mechanically driven by the door? What I mean is, is it directly connected to the door, not controlled by any electronics or anything.

Mike,

I had had the Pilz safety stuff in mind and gave them a call, they'll be coming out here next week to check out the project. She said that they had just completed an application for a hydraulic press so that may be the way we go.

Thanks again.

 

[Eric Nelson]

Yes, the jam bar system is totally mechanical. The "arm" in my drawing is cam operated off the sliding front gate (access door). It lifts the arm when the gate reaches fully closed, allowing the round bar to pass beneath it. When the gate is opened, the bar drops down. If the press tries to close, the bar will "jam" into the cutouts of the round bar. Notice that if the press tries to open with the gate open, it can, because the angled portions of the round bar will lift the arm up (like a ratchet).

I'll try to find a picture as my description probably makes no sense...

Since you have no sliding door on your machine, AND it's a vertical press, the arm would have to be actuated by a solenoid or something (gravity doesn't work sideways!).

Let me look around for a picture to help clarify this (or maybe someone who knows what a jam bar is can chime in with a better explanation?).

beerchug

-Eric

 

[glaverty]

Eric,

I completely follow what you are talking about I was just wondering how I could apply it to my application since like you said I have no door and it is vertical not horizontal like an injection molding press.

I've seen a lot of injection molding presses(my dad builds injection molds) but never realized they had that bar on them, but I guess it would make sense to have a mechanical stop.

Do they have those on the electric presses as well? Those things clamp closed pretty quickly.

 

[ed]

I've worked for an auto maker where redundant safety devices were required on an assembly machine, not a pressing machine. The safety switches on all the guards had two N/C contacts and two N/O contacts. Wired back to the main panel using two seperate circuits for the closed contacts. Then connected to a Pilz relay designed for this type of application. The logic from the Pilz fed the MCR without using any PLC input. The MCR, held closed by the safety, controlled all the PLC outputs. Self-centering valves are used on all hydraulic cylinders, thus removing power freezes movement. The N/O part of the switches were used thru the PLC to show which gate was open. As long as there were two paths for the safety circuits, the redundancy aspects were satisfied. Also included on the control panel was an "ALL STATIONS RETURN" which forced movement of all the cylinders to the home position. FYI

 

[Jvans]

http://212.114.202.55/en/products/safetyintegrated/simotion/index.cfm

Sorry, try this link

John

 

[thunda]

We use about 24 vertical presses and 21 horizontal presses between 400-800 ton the horizontal locking method(ratchet type ) we call die scotch, not sure why. The vertical ones are smaller and they are called ratchet dogs we monitor the locking pin and the solenoid for the ratchet dogs. breaking the light curtains will stop the cycle, carefull because if the operator leaves his hands on the palm buttons clearing the light curtain will resume the cycle. each press only has one slc (AB or Omron) all safety guards are monitored by a trojan safety relay system. and our newewst press is only as couple of months old.

 

[thunda]

I was just thinking I can take my camera to work monday an show you the vertical safety system (ratcheting type). I will also try to get a picture of the horizontal style but they are pretty much the same.

 

[thunda]

Geez I hope I did this right this should be a picture of the "ratchet asssembly" on a vertical hydraulic press you can see the notches that prevent the upper platen from 'drifting' too far. One warning if you set the final stopping (extreme up) position wrong the press will jam on the teeth and the pneumatic cylinder is not strong enough to pull the dog free.

 

[thunda]

hey it works. this picture shows the operating part of the system and you should be able to see the cylinder I was talking about.

 

[Eric Nelson]

Wow, what a nice, clean piece of equipment...

No, really, thanks for the photos. I think it will make it a lot easier for glaverty to 'picture' what we're talking about...

beerchug

-Eric

 

[glaverty]

Thanks for the pictures, I thought I knew what Eric was describing and your pictures are pretty much what I invisioned.