Roller pressure simple calculation method

In fact, any offset press has a theoretical pressure. We must carry out a variety of adjustments (adjusting gaps, changing the lining) based on this theoretical pressure to achieve the desired printing pressure to meet the printing requirements. This article will take the basic parameters of a model as an example to introduce the calculation of the theoretical pressure. Formulas, rough calculation formulas for thick paper, precise calculation formulas for thick paper, and a set of test data, with a view to enabling the printed friends to use flexibly in practical work:

example:

The technical parameters of a model are as follows:

gap:
Between the plate cylinder and blanket cylinder 3.70 mm
Between the blanket cylinder and the impression cylinder 3.05 mm

Lining:
Plate cylinder (including plate, liner) 0.65 mm
Rubber roller (including rubber, liner, liner) 3.25 mm

With these technical parameters, we can use a simple formula to calculate the theoretical pressure:

Theoretical pressure formula:
Lining sum - gap = pressure

Calculation:

First calculate the pressure substitution data between the impression cylinder and the blanket cylinder: 3.25-3.05=0.20 (mm)
Second, calculate the pressure substitution data between plate cylinder and blanket cylinder: 3.25+0.65-3.70=0.20(mm)
The pressure between the three rollers is 0.20 mm without printing. However, during normal printing, a normal printing paper (standard printing paper) should have a thickness of 0.10 mm between the impression cylinder and the blanket cylinder, and the printing pressure between the impression cylinder and the blanket cylinder should be 0.30. Mm.

Conclusion: The printing pressure of this model should be kept within the above calculated range, that is, 0.20 mm between plate cylinder and blanket cylinder, 0.30 mm between blanket cylinder and impression cylinder.

If the thickness of the printed paper is less than 0.10mm, we can make no adjustments and draw down the liner. When printing thin paper, the printing pressure should be smaller, so we do not need to adjust to ensure the printing pressure of thin paper, because our minimum pressure can also be guaranteed at 0.20mm.

If we print paper thicker than 0.10mm and less than 0.20mm, we can adjust the following formula:

Coarse thickness of thick paper (adjust only the gap, no lining) Calculation formula:
X=3.05+paper thickness-0.10
Where: the gap between the blanket cylinder and the impression cylinder that is required to be adjusted when printing X thick paper

If we print paper thickness greater than 0.20mm, we can adjust according to the following formula:

Accuracy of thick paper (adjusting gaps and reducing liners) Formula:
X = 3.05 + paper thickness - 0.10-B
B = (paper thickness - 0.10)/10
Where: X prints thick paper when required to adjust the gap between the blanket cylinder and the impression cylinder.
B Rubber roller's pumping capacity

The test basis for the amount of paper pulled:
We have organized trainees to conduct tests several times. After adjusting the gap between the blanket cylinder and the impression cylinder, the gap between the printing cylinder and the blanket cylinder is measured and recorded:

Data 1
The gap between blanket cylinder and impression cylinder: 3.05mm - 3.45mm +0.40mm
The gap between plate cylinder and blanket cylinder: 3.70mm - 3.66mm - 0.04mm
Data 2
The gap between blanket cylinder and impression cylinder: 3.05mm - 3.25mm +0.20mm
The gap between plate cylinder and blanket cylinder: 3.70mm - 3.68mm - 0.02mm

Test Conclusions:
The enlarged gap between the blanket cylinder and the impression cylinder and the narrow gap between the plate cylinder and blanket cylinder are exactly 10:1, which is the source of the amount of paper B.

The third calculation formula can only meet the offset printing machine without rollers, and the roller offset printing machine does not need to perform the gap between the plate cylinder and the blanket cylinder after adjusting the gap between the blanket cylinder and the impression cylinder. Adjustment, the roller offset printing machine can use the second formula to calculate and adjust the thickness of printing paper more than 0.10mm.