pm 74 delivery problems

[jmt]

we are running a pm 74 low pile .i cant get this press to deliver well at max speed (talking about 50 to 80 lb sheet uncoated or coated)it always seems to kick one side of the sheet forward .when i first got to this shop they couldn't get it past 10.000 hr but with some cleaning and proper adjust meant of air im able to get it to 11500 hr before getting into trouble that's with good sheet brakes and all sheet support in .the only problem i see is that the wire for the counter weight for the middle sheet brake has snapped but i didn't think that would cause a delivery prob but i could be wrong.

 

[exheidmech]

Not the easiest thing to get a low pile to run at 13iph. You need everything almost perfect, right paper, all 3 slowdowns likely at maximum and blowdowns probably wide open as well. Usually speed is limited by the delivery of the press and type of paper you are running.

 

[El Heino]

Yes, low pile 74 is the most sensible delivery i've ever seen. My experience is a bit different than from exheidmech. Ususally the faster you run the press the more blast air you need. But the problem at the 74 low pile is that the air you bring into the delivery has not enough posibillities to come out again. If you take a look at the construction you see that it is closed at all sides. What you blow in have to come out somewhere. The more air you use the bigger is the effect to create a "air pillow", the arriving sheets can't come down to the pile fast enough which leads into paper jams...
My recomendation: very defensive blast air adjustments

 

[turbotom1052]

never worked on this model press but my best success with high speed delivering is to use minimum blowdown air. I try to keep the delivery pile high so that the sheet doesnt have a long drop to the top of the pile. Then i use a combination of a late release cam and slow speed on delivery wheels to create a stretching effect of the sheet so that it pulls the sheet taught before the gripper comes off the release cam. Ive had the best success doing it like that. The other thing you might want to look into is to check that your delivery grippers are all set correctly. A single poorly set gripper on any one of the gripper bars can cause what your talking about. Good luck!!!!

 

[FSA]

jmt
have that issue on an older 1/2 size, were the vacuum lines come off the manifold they don't get even amounts of vacuum, so when you set the gauges it looks like one side would have no or very little vacuum and the other side is at full, but the sheets dropped nice and straight. The new guys on the machine all seem to thinks its not right, but they can't get the press to run at anything fast, I come in for the night shift see that bad drop, reset the gauges and away it goes.
FSA

 

[jmt]

thanks all for the help.ya turbotom that's how i have manged to get it to run at nearly max speed just a little air and high piles .fsa will try to mess with gauges because it does look like one side of the sheet is being driven more than the other side.

 

[turbotom1052]

fsa is correct about uneven amounts of vacuum coming off the manifold. You would think that a symetrical setup of the vacuum levers would make for an even distribution of vacuum but ive found that you often need to balance the air by how the sheets deliver as opposed to where the levers are placed. I use these levers to actually "steer" the sheets in the delivery.