Komori Lithrone S40 --Ink Fountain speed control

[Deleted member 16349]

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]

Ink Fountain speed

Ink Fountain speed

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

 

[Deleted member 16349]

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]

Speed Comp.

Speed Comp.

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.

 

[Deleted member 16349]

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

 

[Deleted member 16349]

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.

 

[Servicetech]

Graphical representation of the SET and RATIO functions

The synchronization point is the press speed that changes from SET to RATIO setting, set by console memory setting M2-1 (default setting is 38 i.e. 38% of max speed) Although if I remember correctly, this setting may have a slightly different default setting due to newer, higher speed machinery. At a press speed below the synchronization point the ink feed will be adjusted by the SET value alone, above this same point the ink feed will be INK FEED = (SET x( RATIO / 100)) and then applied to the press speed, probably with a slope intercept formula (y=mx+b)

As you can see the RATIO setting will adjust the high end of the linear slope. A RATIO setting of 100 will result in no compensation of ink feed due to press speed.

 

[Deleted member 16349]

Graphical representation of the SET and RATIO functions

The synchronization point is the press speed that changes from SET to RATIO setting, set by console memory setting M2-1 (default setting is 38 i.e. 38% of max speed) Although if I remember correctly, this setting may have a slightly different default setting due to newer, higher speed machinery. At a press speed below the synchronization point the ink feed will be adjusted by the SET value alone, above this same point the ink feed will be INK FEED = (SET x( RATIO / 100)) and then applied to the press speed, probably with a slope intercept formula (y=mx+b)

As you can see the RATIO setting will adjust the high end of the linear slope. A RATIO setting of 100 will result in no compensation of ink feed due to press speed.

Hi Servicetech,

I have seen this chart. At first I was confused since I could not believe that the ink fountain speed was constant through the whole press speed if Ratio = 100. In thinking about it more, I could see that it would work if the ductor roller makes at least a full rotation when it is against the ink fountain roller.

Since the ductor acts on every three impressions, there is more time to do that and I am guessing the ink fountain roller tends to run faster than on other presses.

I also suspect that the ink film thickness on the ink fountain roller for the ink key range from 0% to 100% is probably smaller than on other presses too.

Does that make sense to you?

Thanks for any more comments.

 

[Deleted member 16349]

Erik,

it will duct 1 time for every 3 plate revolutions no matter what the press speed is

Hi Inkinveins,

Does this cycle time of 1 ductor action for every 3 plate revolutions cause much variation in the print density over that period?

Also a question about the ink key range. I have been told that the full range of movement from closed to open (0% to 100%) is something like 0.016". On these presses, can the total range of ink key movement be changed to make it larger?

In operation can all of the ink keys be moved proportionally higher and lower?

I think the speed of the ink fountain issue is cleared up. I was looking for a proportional speed control and that seems to be doable with this system. Setting the transition speed at 8000 (start of printing) and the Ratio to 175 (14000 top speed on the target press) gives the desired result for what I needed.

For what we are going to be doing, there is no ductor action. The ink transfer will be continuous.

Thanks for any comments.

 

[Alois Senefelder]

Enlightenment !

Enlightenment !

Hello Erik,

I hope the PDF has the information you seek !



Regards, Alois

 

[Servicetech]

Yes Erik, You are correct about the ink ductor, I found a newer explanation of the ink feed system (see note 4 at the bottom).

I don't think there is a way to increase the total range of ink key movement, the key motors have a finite amount of mechanical movement. In fact on older machines, worn keys can cause issues. After a zero set with worn keys, you may not make it to 100% before the mechanical limit of the key motor assembly is reached.

Also I forgot to include what the ink feed motor drives get from the console for a speed reference. the console outputs a 0-10 VDC analog signal to the drive(s). Minimum speed would be 0 VDC maximum is 10 VDC. 0-10vdc is a very common analog signal when transmitting over short distances (inside a localized machine)

 

[Deleted member 16349]

Hello Erik,

I hope the PDF has the information you seek !



Regards, Alois

Thanks for the PDF. I don't think it is exactly the same press but the PDF is of interest. The target press seems to have a larger ink key gap range than the one in the PDF.

 

[Deleted member 16349]

Yes Erik, You are correct about the ink ductor, I found a newer explanation of the ink feed system (see note 4 at the bottom).

I don't think there is a way to increase the total range of ink key movement, the key motors have a finite amount of mechanical movement. In fact on older machines, worn keys can cause issues. After a zero set with worn keys, you may not make it to 100% before the mechanical limit of the key motor assembly is reached.

Also I forgot to include what the ink feed motor drives get from the console for a speed reference. the console outputs a 0-10 VDC analog signal to the drive(s). Minimum speed would be 0 VDC maximum is 10 VDC. 0-10vdc is a very common analog signal when transmitting over short distances (inside a localized machine)

Useful information. I was told that a 0.016" feeler gauge could be slipped into the maximum ink key gap. This should be enough of a range even if it can't be increased. So things look good for testing.

Thanks again.