QMDI Noise while progressing plate PU4

Hi Thanks for all your help so far,

We've just changed a pearldry roll on PU4 for the first time, we removed the old roll, inserted the new roll and turned the press backwards to wrap the plate around the cylinder and then inserted the tail into the emtpy spool and tightened.

Since then the plates do progress however there is a knocking noise comping from PU4 for a few seconds before imaging while it progresses the plate.

I was wondering if anyone had experienced this problem before? or have I done something stupid like wrap the plates around the cylinder in the wrong direction?

Andrew

 

Did you replaced the end cap with the curved tooth on the right spindle.

 

I'm sorry, (new to this press and struggeling to understand)

Are you reffering to the gearwheels which are inserted into the shaft?
I believe I put these in the right order according to the diagrams on the roll support device

 

Yes, I do. And are you sure.

 

I'll remove/reinstall the roll and make sure

Thanks Marc

 

You do not need to remove the roll to see if they are in correctly. You can stick your head in there and look at the gears to see if they are meshed properly. If they are not, when the roll is winding it will make a chattering noise. Also when you were putting the plate material in, if the gears were the wrong direction you would have had a very difficult time trying to get the latch to lock properly.

Another problem could be the material was not put on the take up spool straight. This causes a bubble along the lead edge of the plate material during the winding process which can actually hit the form rollers causing a popping sound. Once the material gets pulled tight at the end of the process the sound goes away but you will notice fit issues along the lead edge in the print.

Just so you are familiar with the plate winding process I'll give you a run down.

1. You select the job to be imaged and hit the image button. The press beeps. You hit the button again.
2. The press starts to go backwards and you hear a slight popping sound. This is the air piston pushing a shaft into the middle of the plate cylinder causing a lock and pawl mechanism to disengage the new plate material spool allowing it to move. At this point the plate material will be loose if the press were to stop.
3. The particle brakes on each unit being imaged lock up and holds the big gear in place you see on the catwalk side of the machine when the doors are open. On the end of the shaft which goes into the plate cylinder from that gear there are splines. The take up spool has a gear that runs on these splines. When the particle brake holds this in place the take spool is now able to turn due to the press going backwards thus allowing a new plate to be wound onto the cylinder.
4. The machine now puts the blanket to the plate cylinder to help smooth the plate. During this process the particle brake will pulse a few times to pull the plate tight.
5. The press slows to a stop and starts to rotate in the forward direction for imaging.

At least that is the way I remember it. I have not seen one of these machines run in 7 years. LOL

Alot of people think the electric motor that turns the big gear when loading new plate material is used during the imaging process. It is not. The only time it is used is during the plate loading function when using the DI keys.

 

Thanks very much for all your replies,

I'll check all the tips posted above and get back to you, we are just waiting for our Ink Fountain roller being reinstalled, but have been told it will be ready today.

 

I'm abit late in getting back (the roller was only finished this morning)

I stuck my head in as suggested and as Paul & Marc suggested the gears where not meshed correctly I must not have swapped them correctly as I should.

Thanks for your help and I just hope I haven't done to much damage

Andrew

 

Andrew,

It won't cause any damage other than rounding off the tips of the gears a bit. If you did not catch it, the rolls would have come out and that my friend would have caused some damage...

 

Thanks once again for your help Paul, I'll make sure to take more care in future

Andrew