roland 700 drive side doubling

[JOHNYPRINT]

Hi all
I would welcome any ideas and advice on an issue that we have on a roland 700 6colour press 1997 with a perfector drum between units 2 and 4 ,the machine also has double impression cylinders and double transferta drums between cylinders.
We are getting the double on decks 2 and 3 (deck1 not used), decks 4,5and6 print sharp.
the double is at the back corner of the sheet on the drive side and it alternates left and right.I have just started to clean and re_set all grippers throughout the press, i'm up to deck 4 after starting from deck 1. We also have a similar problem on a KBA rapida 104 8colour perfector, the same alternating double happens after the perfector.
If anybody could help with this issue i would be thankful, i'm worried it might be some deeper mechanical issue. Is there a roland engineer or demonstrator on this foram.
regards johnyprint

 

[Alois Senefelder]

re - Doubling

re - Doubling

Hello Johnyprint, I take it you "HAVE" checked the obvious first -- Blanket Tension ???


Regards, Alois

 

[JOHNYPRINT]

Yes, thanks for your reply but all the simple things have been done . it's a bit more in depth than that, the double alternates from sheet to sheet left then right of print, my hunch is the double impression cylinder but cant be sure. regards johnyprint

 

[akiyama_king]

Hi johny

Not sure if you have been checking this as you were checking the grippers but usually a torsion bar thats out of set or a little slack tends to cause doubling on the 700 so check your torsion bars on the imp cyl and transfers, i'll be honest im not sure how to check that but the first thing i thought was a torsion bar would cause this.

Also you say it is doing it on units 2/3 if this is the case it wouldnt be the perfectors as the perfector should double at unit 3 because the perfector is after unit 2 and the transfer would be after unit 1

I assume youve checked the cylinder Cam followers are nice and free and youv kept them well greased?

has the press done it ever since youve had it or just recently?

Hope this helps keep us informed

 

[JOHNYPRINT]

Thanks for your reply akiyama king
I will talk to our on site engineers when i go back to work on monday and do some more work on the issue. We have had issues with the torsion bars breaking and having to be replaced. i have greased cam followers and done the usual checks as this was one of the first things i thought of but i think i will check again when i get back.
regards johnyprint

 

[akiyama_king]

Thanks for your reply akiyama king
I will talk to our on site engineers when i go back to work on monday and do some more work on the issue. We have had issues with the torsion bars breaking and having to be replaced. i have greased cam followers and done the usual checks as this was one of the first things i thought of but i think i will check again when i get back.
I've been on the press 6months but they have had the problem for years and given up on it ,but i still think there is an answer. regards johnyprint

Johnny, if its not the torsions and the grippers are set, it could be (although it is unlikly) that one of your main press Gears has some damage to it, and as it is doing it to 2 units one after the other where you would have two gears working with each other it may well be that.

Not sure why you say unit one aint running (has it been used as a spares unit) or do you just never need six colours but if you can get ink on the rollers and get it into imp if it is a gear issue at unit two it should double and unit one aswell because unit two and unit one would be working together.

if you say theyve had the issue years i assume theyve done all the torsion bas and all that shit so albeit a small possibility its worth a go

you can remove covers on the drive side and check the gears, youll probs have to take the footboards of aswell to get a good look.

Also another longshot, if you have a accurate engineers level check if the units 2/3 are level or not.

I know all these are longshots but as theyve had the problem yrs i rekon its going to be something quite technical (not as simple as a gripper setting)

Good luck

 

[kbarz]

johnny all above is true, but this might be the problem. make sure that all 4 ink form rollors are not oscilating from side to side,the #4 form will cause a slur on the tail end of sheet if she is moving from a to b side

 

[akiyama_king]

Any Luck yet Johny?

 

[JOHNYPRINT]

not yet. we are going to look at the issue next week. today i printed a job on B1 size 100gsm matt and the doubleing was 99%gone, that would make me think grippers because if it was mechanical it would still happen and maybe even worse i think, maybe the outside grippers are set ok and the middle grippers where we run a lot of SRA1 work are'nt in such good condition, makes me think it's not as serious as i thought it might be

 

[akiyama_king]

not yet. we are going to look at the issue next week. today i printed a job on B1 size 100gsm matt and the doubleing was 99%gone, that would make me think grippers because if it was mechanical it would still happen and maybe even worse i think, maybe the outside grippers are set ok and the middle grippers where we run a lot of SRA1 work are'nt in such good condition, makes me think it's not as serious as i thought it might be

Thats Good To hear, I would have thought it would be very bad on 100Gram so i think your problem is pretty much gone...Well Done

 

[JOHNYPRINT]

sorry akiyama
didnt make it clear ,it's still doing it on SRA1, but not as bad on the B1 size paper.
I will do some more gripper cleaning and setting on monday or tuesday, fingers crossed.

 

[akiyama_king]

sorry akiyama
didnt make it clear ,it's still doing it on SRA1, but not as bad on the B1 size paper.
I will do some more gripper cleaning and setting on monday or tuesday, fingers crossed.

Do you run alot of heavy board?

 

[JOHNYPRINT]

Not a lot, maybe a couple times a month, max 300gsm

 

[jbeniston]

You are heading in the right diection. The tansferter cam followers should be checked for wear, the gripper pads should be examined and cleaned , the pad bar height checked and adjusted and then grippers set. It is often the case with Roland 700 series machines that because of deterioration of the component parts wearing and lack of appropriate maintenance, the timing of the sheet transfer is negatively affected.
You need to set the perfector grippers, both the straight and perfecting set, and check the pad bar height setting. Also check that the anchor cam followers on the gear side are not seized up or hard to turn and at the same time check the segment gears on the operators or B side (there are two of them on each half of the perfecting drim) They should be coated with white grease. These should be greased every 8 hours! with the appropriate grease and gun. 1 stroke to each grease fitting. Do this at the shift change, it will take about 1 minute. It's invaluable p/m.
Having said all this you should really get the help of a qualified MR mechanic to get all this done. I don't know your location but there has to be someone in the area you can use.
Finally you have to make sure that the infeed is all set up properly, i.e. gripper bite, front lay settings, and so on.

 

[JOHNYPRINT]

Roland 700 perfector

Roland 700 perfector

Hi jbeniston
Thanks for your input, i think we might have solved the double problem, the sheet was not being held properly through the gripper transfer between the second deck impression cylinder and the perfector drum straight print grippers(flying gripper transfer), we put more tension throgh the gripper bars on the perfector by turning an allen bolt just behind the cam follower also some of the gippers were set uneven, we will monitor the situation as and when we get on to different thickness stock. I think the gripper pad bars are set ok they are on 0.2 both sides, we mostly run thin stock, a couple of times a month we might use 250-300 gsm. please let me know if there is anything tou think we may have overlooked while setting the straight print grippers.
The next issue we have is that the perfector will not change over from straight print to perfect, i have been on the press 6-7 months and have been told that it's been like that for a long time, i dont know the original problem that went wrong, but now because it's always been in straight print i would imagine it would struggle to change over, i am going to ask the managers to get an engineer in but is there anything obvious we should look for.
thanks for all your help , regards johnyprint

 

[reyltech]

Grippers and pad heights

Grippers and pad heights

Hi there, I would focus on grippers and pad heights especially. The Roland 700 gripper tips wear out and you can set and reset and still have problems. How many impressions do you have??? It will not be the gears as if it was you would know it. If it was gears that machine wouldn't print period. It would self destruct. I am a ex-Roland Tech trained in Germany. Torsion bars are a problem but mainly due to design flaws in my opinion. The torsion holders do not support the torsion bar correctly on the load side. I would focus on gripper tips and pads.

 

[Deleted member 16349]

Hi all

We are getting the double on decks 2 and 3 (deck1 not used), decks 4,5and6 print sharp.
the double is at the back corner of the sheet on the drive side and it alternates left and right.I
regards johnyprint

This very localized doubling, at the end and at only one corner, suggest to me that it might not be mechanical problem but might be distortion of the paper in that area due to what you are printing there.

I know of a press manufacturer that was thinking of distorting the image to the plate in different ways to compensate for distorted print. With your problem, it might be possible that there is some heavy coverage close to that area that is pulling on the paper inconsistently when the ink film is being split and it settles down in slightly different positions causing the double.

Probably not the cause of your particular problem but it was a thought.

 

[JOHNYPRINT]

Thanks for the replies.
eric, the double happens even when there is little ink in that area, eg:just the colour bar. but thanks for your input, i will keep your opinion in mind, it all helps.
Reyltech thanks for your reply, the press has done 200million. could you let me know how to set the gripper pads, also could you tell me if it is easy to re-posision the cam a little bit so that the cam follower shuts the grippers a little bit earlier thus eliminating the flying gripper transfer, i noticed in the parts book the cam can be un-bolted and replaced or if i am correct the bolt holes are designed so that the cam can be moved to forward or retard the gripper opening. any thougts

 

[Deleted member 16349]

Thanks for the replies.
eric, the double happens even when there is little ink in that area, eg:just the colour bar. but thanks for your input, i will keep your opinion in mind, it all helps.
:

Here is another possibility. If it is not the ink, could it be the water on that side. If the water is applied inconsistently, it might dampen the paper differently and cause variations in the width of the sheet. Just another low probability thought.

 

[JOHNYPRINT]

Thanks eric, All the basic issues regarding ink, paper ,damp, blanket tension etc have been eliminated from the equation. We are looking for a mechanical solution to the problem, but thanks anyway, sometimes you need to stand back and look at an issue again , going back through all the basics.
what i need to find out next is how to un bolt the cams and move them a fraction so that we get the required amount of control on the sheet during the transfer from imp cylinder to transferter.
regards johnyprint