Printing image gradually moving to OS

Dear all

The image of unit 2 is gradually moving to the OS. When we stopped the machine and print again, the image position is back to normal, but after about 30 sheets, the image is moving to the OS as well.

I've checked the pinion gear and the spring in the DS and it looks fine to me.

I need advice on this issue.

Rgds
Ray

 

It is nearly impossible to provide you with a possible solution to your issue without more details. At least tell us what kind of machine you have.

 

Dear Mr. Exheidmech

My machine is GTO-Z.

Rgds
Ray.

 

Very likely the bearer pressure between plate and blanket is too high. Possibly someone tried to tighten it to rid the press of a streak. If the bearer pressure is set too high, the plate cylinder will want to walk tword the operator side due to the helical cut of the drive gears. The pressure between plate and blanket is too high for the springs on the plate cylinder gear to hold the cylinder tword the drive side resulting in a moving image. This also explains why the image goes back to its normal position when you come off impression.

 

Mr.Exheidmech

I've checked the bearer pressure between plate and blanket cylinder, and it was 0.3mm if impression is on. Is it normal?

Then I found out that when the machine is not running, i tried to move the plate cylinder to the drive side, ( i turn it clockwise), the cylinder doesnt move at all and it feels very light.

Can you help me with this issue?

 

where exactly are you getting a distance of .3mm at? With impression on you should be able to measure any gap between plate and blanket. There should be actually quite a bit of pressure between the 2 when on impression. The dial I think you are talking about is for either the circumferential or lateral movement of the plate cylinder. When you turn the adjusting screw clockwise or counter clockwise you should also see a ring gear between the cylinder and the side from moving.

 

Mr. Exheidmech

The ring gear that placed between the plate cylinder and the body at the operator side is moving, either i turn the lateral clockwise or counter clockwise.

When the machine stop, i turn the lateral counter clockwise, i see the plate cylinder is moving slowly to the operator side. And then i turn it clockwise, the cylinder plate doesn't move back to the drive side, and it fedls very light as if i was turning nothing.But the ring gear is moving when i either turn it clockwise or counter clockwise.

Need your advice please..

Rgds
Ray

 

The distance. 3mm is from bearer of cylinder plate and cylinder blanket when i switched the impression on.

 

You should not be able to measure bearer pressure with a feeler gauge with impression on. There should be no gap between blanket and impression. As far as moving circumferential or lateral register, this should only be done while machine is running.

 

Yes i know moving circumferential and lateral register can only be done while the machine is running.

I will try to describe to you.

1. When the image is moving to the OS, I stopped the machine. Then I ran the machine again, turned the lateral clockwise to move the plate cylinder to the DS. The result is the image is way too far to the DS.

2. Then I ran the press again. When I see the image is movinv to the OS again, I stopped the machine. Then i ran the press again without turning the lateral register. The result is the image is back to its normal position.

3. Because the image is always moving only to the OS, I decided to move the cylinder plate to the DS while the press is stopped. Thats how I found it out.

Any advice to solve this issue?