Komori Lithrone S40 --Ink Fountain speed control

[Erik Nikkanen]

Hi All,

I need to talk with a control engineer or control technician who fully understands the speed control to the ink fountain roller on a Lithrone S40 press.

I have been told some things about this system that really seems strange but that can happen.

The person should understand the input reference signals to the drives. The discussions can be offline.

I will also try to find such a person by contacting Komori America directly.

Thanks

Erik

[inkinveins]

Erik,

Komori's ( and I am sure other presses too ) are equipped with speed compensation for the fountain roller. As I am sure you know, they call it " Ratio ". for simplicity of math, I will give you an example of a sweep or set of 50 and a ratio of 150, the actual ink feed at full speed would be 65 ( 50 plus 15 ), and the actual ink feed at half the maximum press speed would be 57.5 ( 50 plus 7.5 ). It is a linear relationship of speed and ink feed. If the ratio is set at 100, then there is actually no speed compensation, and the ink feed would remain static independent of press speed. This is a very simplified explanation. Hope this helps

[Erik Nikkanen]

Erik,

Komori's ( and I am sure other presses too ) are equipped with speed compensation for the fountain roller. As I am sure you know, they call it " Ratio ". for simplicity of math, I will give you an example of a sweep or set of 50 and a ratio of 150, the actual ink feed at full speed would be 65 ( 50 plus 15 ), and the actual ink feed at half the maximum press speed would be 57.5 ( 50 plus 7.5 ). It is a linear relationship of speed and ink feed. If the ratio is set at 100, then there is actually no speed compensation, and the ink feed would remain static independent of press speed. This is a very simplified explanation. Hope this helps

Inkinveins, thanks for your comment. It is basically what I have been told by the litho supervisor and by the local Komori tech but the explanation still does not make sense to me. It maybe how things are worded or something else.

When you say that with a Ratio of 100, ink feed would be static and independent of press speed, are you saying that the ink fountain roller stays at a constant rate of speed (rpm) even thought the press speeds up?

To me this is not workable.

If you say the sweep setting stays constant and independent of the press speed, I could agree with this because all it would mean is that the ink fountain roller speed increases proportionally with press speed but maintains a set percentage that is used in the control system.

Your math might also be incorrect. From the Komori form I saw, the set point is multiplied by the ratio/100. That would result in 50 x 150/100 = 75

There is probably nothing wrong with the control system ( I hope). It might only be how people are trying to describe it. In the end, it has to make sense and right now I have confusing explanations.

A control engineer at Komori should be able to describe the inputs and how they are used.

Thanks for the comments.

[inkinveins]

Inkinveins, thanks for your comment. It is basically what I have been told by the litho supervisor and by the local Komori tech but the explanation still does not make sense to me. It maybe how things are worded or something else.

When you say that with a Ratio of 100, ink feed would be static and independent of press speed, are you saying that the ink fountain roller stays at a constant rate of speed (rpm) even thought the press speeds up?

To me this is not workable.

If you say the sweep setting stays constant and independent of the press speed, I could agree with this because all it would mean is that the ink fountain roller speed increases proportionally with press speed but maintains a set percentage that is used in the control system.

Your math might also be incorrect. From the Komori form I saw, the set point is multiplied by the ratio/100. That would result in 50 x 150/100 = 75

There is probably nothing wrong with the control system ( I hope). It might only be how people are trying to describe it. In the end, it has to make sense and right now I have confusing explanations.

A control engineer at Komori should be able to describe the inputs and how they are used.

Thanks for the comments.

Erik,
You are correct, my math was wrong, I was just throwing generic numbers out there to demonstrate a crude example of the speed compensation. Since a ratio of 150 would would increase the total set value by 50 % at maximum speed, yes 50 plus 25 ( 50 /2 )would equal 75, so it tells me there is nothing wrong with the control system you are working on.
Also, you did understand me correctly when I mentioned that if the ratio is at 100 the ink fountain ball speed remains a constant, regardless of press speed. The actual ink feed value will be displayed in your " Set L.M.H. / flush " display on your console. Try ramping up press speed with the ratio at 100 and you will see that the actual ink feed ( location mentioned above ) will remain constant. There is no transparent control system ( like some other presses have ) that will actually ramp up your ink feed other than the visual one I just discussed. Finally, you did mention that if the ink feed did remain static independent of press speed, that it was not workable. I am not so sure if I agree with this, because ducting or ink feed is linear, in that it will duct 1 time for every 3 plate revolutions no matter what the press speed is, so wouldn't this make speed a nonfactor of the input and output of ink. The jury is still out on that one for me.
P.S. I sent you a private message with my cell phone number and current position, take a look at that correspondence and feel free to give me call if you want to discuss further

[CKL]

Erik

If you have run a press with conventional dampners it is easier to understand the methodology. Some old press guy may also be able to help.

[Erik Nikkanen]

Erik,

Also, you did understand me correctly when I mentioned that if the ratio is at 100 the ink fountain ball speed remains a constant, regardless of press speed. The actual ink feed value will be displayed in your " Set L.M.H. / flush " display on your console. Try ramping up press speed with the ratio at 100 and you will see that the actual ink feed ( location mentioned above ) will remain constant. There is no transparent control system ( like some other presses have ) that will actually ramp up your ink feed other than the visual one I just discussed. Finally, you did mention that if the ink feed did remain static independent of press speed, that it was not workable. I am not so sure if I agree with this, because ducting or ink feed is linear, in that it will duct 1 time for every 3 plate revolutions no matter what the press speed is, so wouldn't this make speed a nonfactor of the input and output of ink. The jury is still out on that one for me.

Inkinveins,

Thank you very much for your comments. It has helped.

I have done some of thinking in how a system with a constant speed ink feed roller would be able to supply more ink as the press speeds up. I can now see how this system IS workable but maybe is not ideal.

I need to do more thinking about this since this brings up some totally new ideas for me. I will probably be back with more questions.

Thanks again.

[Kaoticor]

Just curious as to how some other printers run, what do you guy set your ink ratio number at in your shop?

[REYES1377]

Just curious as to how some other printers run, what do you guy set your ink ratio number at in your shop?

For me it really depends on coverage. But on a average we run with a SET of 20 and RATIO of 140

[Erik Nikkanen]

For me it really depends on coverage. But on a average we run with a SET of 20 and RATIO of 140

Nice to see some operators comment.

A question for operators. To increase density, do you tend to do this by increasing ink key settings or by increasing the SET value.

Does changing the SET value have a big affect on changing density.

Thanks.

[Kaoticor]

Nice to see some operators comment.

A question for operators. To increase density, do you tend to do this by increasing ink key settings or by increasing the SET value.

Does changing the SET value have a big affect on changing density.

Thanks.

Erik,

I will almost always adjust ink key settings rather than set value. It's just what I personally feel works better for my production requirements.