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WRENDHBENDER
18-07-2012, 06:42 PM
Having a problem with the second stage will not unload in auto if slide goes to 100% can switch to manual and unload but will not in auto , tested everything i know. Plc , control valves etc any help would be appreciated

RANGER1
18-07-2012, 09:17 PM
WRENDBENDER,
I can only suggest that you increase pulse time to unload, as full load always takes a bit longer to unload from.
Also if there are any valves on hydraulic system that may need opening up a bit more.

If "0" rings at back of unload cylinder, or unload piston are damaged it could also cause issues also.

Try that & let us know how yo get on.

Usually on a compound we programme it to full load & leave it there, using booster side to load/nload.

Magoo
19-07-2012, 07:03 AM
Hello
Possibly the plc program needs to see max load position before auto unload, the position of feed back pot could be out of wack or micro switch max position could have moved and cannot see 100% position. But manual forced unload will work, just a thought.

Grizzly
19-07-2012, 07:34 AM
Hi Magoo.
So "out of Wack" is a technical term then?
Sorry could not resist it!
I would however agree with both you and Ranger there is it would appear a command or reference point, be it analog or digital missing.
Good luck wrendhbender and let us all know how it goes?
Having though about this a little more, the logical answer is!
Whatever value controls the unloader solenoid vale is not being reached.
So identify what you capacity control operations set to?
I.e. Auto, Remote digital etc. etc.
Once you know how the unloader is controlled you can identify where in the sequence is the fault.

Hopefully that helps?
Grizzly

Ravi Upadhyay
19-07-2012, 10:25 AM
sir, we have experience of same kind of problem in mycom compound machine. we overcome from this by replacing one of the damaged o ring of unloader assembly. I think this may be one of the reason in your case.

Ravi

Grizzly
19-07-2012, 10:34 AM
sir, we have experience of same kind of problem in mycom compound machine. we overcome from this by replacing one of the damaged o ring of unloader assembly. I think this may be one of the reason in your case.

Ravi

How do you explain that the unloading works fine when in Manual mode then Ravi?

Ravi Upadhyay
19-07-2012, 11:20 AM
Sir, i m not explaning anything. As i mentioned we have faced same kind of problem n rectify wt above indicated work.

josef
19-07-2012, 12:16 PM
I guess, cam, bearing? pin?
PLC sends a pulse, I keep my hand still.

Grizzly
20-07-2012, 07:30 AM
Sir, i m not explaning anything. As i mentioned we have faced same kind of problem n rectify wt above indicated work.

I think I owe you and the others an appology, as your answer makes sense.
I was blinded by my own take on the described fault.


Basically what is being said is if there is sufficient wear within the unloading system components.
Then the pulsed injection frequency (of the oil into the unloader) would not be sustained enough!

Therefore wrendhbender, their advice should be heeded.
Sorry Guys!
Grizzly

RANGER1
20-07-2012, 10:03 AM
Out of interest I had a client with similar problem on a Mycom.
Found on site visit 100 kpa net oil pressure (oil trip set a bit low too), so it did'nt have enough grunt to move slide valve!

WRENDHBENDER
20-07-2012, 02:28 PM
Been running through settings for pulse times, may be the problem will let you know current kpa on hydraulics at 1120. Thanks for all the info.

RANGER1
21-07-2012, 09:32 AM
Been running through settings for pulse times, may be the problem will let you know current kpa on hydraulics at 1120. Thanks for all the info.

Thanks, oil pressure should be minimum 200 kpa or 30psi above discharge pressure