Anatomy of the Ink Supply System of Sheet-fed Lithographic Offset Press

The general structure of the ink system

The ink supply system of the sheet-fed lithographic offset printing press includes ink supply, ink distribution and ink deposition. The structural form of the ink system is similar to that of the various models. The schematic layout of the ink roller in the monochrome group is basically as shown in FIG.



figure 1

The main components of the ink supply system include an ink supply roller 1; an ink transfer roller 2; an ink supply roller 3, 9; a heavy roller 4, 6, 11; an ink distribution roller 5, 7, 8, 10, 12; an ink roller 13, 14, 15, 16 and ink fountains, ink trains, inking units, pressure regulators for each roller. The ink distribution roller 7 and the ink distribution roller 12 are actually ink storage rollers, and they have exactly the same parts as the other ink distribution rollers, but their functions are slightly different.

How the ink system works

The ink is adjusted by the local ink amount of the ink blade by the ink fountain roller 1 in the ink fountain, intermittently supplied to the ink transfer roller 2, and the ink transfer roller 2 transmits the ink to the ink squirting roller 3 in an oscillating manner. The ink roller rotates while being rotated Towards the string, the ink is evenly distributed in the axial direction, and is conveyed to the uniform ink roller 8 through the even ink root 5 and the iron roller 6 of the even ink portion. The inking roller 8 divides the ink-jets into two groups, and is conveyed to the inking rollers 15, 16 via the severing roller 3 all the way. In the other pass, the serigraphy roller 9, the inker roller 10, and the serigraph roller 3 are sent to the inking rollers 13, 14. 13, 14, 15, 16 finally deliver the ink to the plate cylinder for printing.

The ink distribution function of the uniform ink portion can be divided into two aspects. On the one hand, axial ink distribution, that is, ink stringing. The ink is evenly distributed in the axial direction of the ink roller by axially distributing the ink in the four ink rollers 3, 9. The ink volume of the ink stringer is generally 20-25 millimeters. The ink amount of the ink stringer is, of course, larger, the better, but the larger the ink amount is, the more difficult the design of the ink stringer is.

On the other hand, it is uniform ink. The circumferential evenness of the ink is through the roller compaction between the ink rollers, and the ink is thinly pressed. After the ink passes through several pairs of ink rollers, the ink is rolled, rolled and thinned, cut and separated to form a uniform ink layer whose thickness meets requirements, and is then transmitted to the ink roller.

After the ink is pressed by the ink roller, the thickness of the ink layer output is related to the pressure between the ink rollers. The greater the pressure, the thinner the ink layer thickness. The amount of ink output when a pair of ink rollers transfer ink (usually the thickness of the ink layer indicates that ya+yb is approximately equal to the input ink volume xa+xb, and ya is equal to yb (see FIG. 2).



figure 2

Xa is the thickness of the ink layer transferred from the upper ink roller to the ink roller a, xb is the thickness of the ink layer remaining after the ink roller b transfers the ink to the lower ink roller, and ya is the ink adhered to the rollers after being rolled by the a and b ink rollers. The thickness of the ink layer on the ink roller a, yb is the thickness of the ink layer attached to the ink roller b after rolling, the ink rollers a, b roll the two layers of xa and xb ink into a single body at the rolling point, and roll through the roller compaction. After the point, the adhesion force between the ink roller and the ink and the adhesion force between the inks tear the ink into two parts and adhere to the ink rollers a and b, respectively. Since the mutual attraction between the ink and the ink inside the ink is the same, the thickness of the ink layer adhering to the ink roller a and the ink roller b is equal, that is, ya=yb.

Then, the following relationship can be established:

Xa+xb=ya+yb.............................................(1)

Ya=yb......................................................(2)

Xa>xa......................................................(3)

The above relationship can be applied to the ink transfer amount calculation for each pair of ink rollers from the ink delivery roller 1 to the ink set 13, 14, 15, 16 throughout the ink feed line. Moreover, the half of the amount of ink discharged by the upper pair of ink-conveying ink rollers is a part of the amount of the lower-ink transfer ink roller.

That is: yn=x(n+1)................................................(14)

n is 1, 2, 3, ...................................................15

Use formula (4) to list the ink transfer relationship for the entire ink feed line (see Figure 3):



image 3

When the ink fountain is set to have an ink volume of 100, the ink transfer rate on the ink form rollers 13, 14, 15, 16 can be calculated using the above ink transfer formula. When the ink fountain unit volume is known, the above The ink transfer relationship calculates the unit ink amount on the ink rollers 13, 14, 15, and 16, respectively.

The number of uniform ink rollers is greatly related to the effect of ink distribution. The number of uniform ink rollers is large, the number of times the ink is rolled and torn, and the ink layer is more uniform.

Ink rollers 4, 6, and 11 are heavy rollers, and their most important role is to absorb the vibration in the ink system by their own weight in addition to the ink, and to reduce the ink layer generated by the relative vibration between the ink rollers. Uniform.

The ink rollers 7 and 12 in addition to the uniform ink, in fact, to the flexible part of the ink system, like the reservoir, play the role of ink storage and regulation. When the amount of ink is large, the ink in the ink path can be absorbed and stored. When the amount of ink supplied is small, the ink can be output to the ink path to maintain the stability of the ink in the ink path. According to the calculation, the amount of ink stored by the ink roller 7 occupies about one quarter of the ink transferred by the ink roller 6, and the amount of ink stored by the ink roller 12 accounts for about 8% of the total ink transfer amount. It is a little different from the ink storage function of the entire ink supply system. It not only participates in the ink storage and adjustment of the entire ink supply system, but also stores and adjusts the ink supply system itself.

In addition to supplying ink to the plate cylinder during the printing process, the ink form rollers 13 and 14 may perform ink collection in addition to ink filling of the ink rollers 15 and 16 . When the amount of ink transferred to the ink system is too large, the amount of ink on the printing plate is greater than the amount of ink carried by the ink rollers 13, 14, that is, xb, xa in relation (3). According to the relational expressions (1) and (2), it can be known from the analysis that the inker rollers 13 and 14 will take ink from the printing plate. This effect is conducive to the stability of the ink color of the printing process during the printing process.

General principles for designing ink rollers for ink systems

The ink roller design for the ink system generally follows the following principles.

a. The higher the printing speed, the greater the number of ink rollers.

b, the diameter of each ink roller is not equal, and the ratio of the diameter of the adjacent ink roller should be endless.

c. The inking rate of the former ink roller (15, 16) is large, and the inking rate of the latter ink roller (13, 14) is small.

d, the inking coefficient is the ratio of the total area of ​​the ink roller and the printing plate area, should be greater than 1; the uniform ink system is the ratio of the total area of ​​the uniform ink roller to the printing plate area, should be 3-6; the ink storage coefficient is the inking coefficient The sum of the equidistant ink coefficient may be appropriately larger, but the over-inking speed is affected by the general meeting; the number of ink-jet lines is the number of the contact lines transmitted by the ink in the ink portion, and the larger the better.

e. The surface linear velocity of each ink roller should be equal to the surface linear velocity of the plate cylinder.

f. The ink roller should have sufficient rigidity and good balance.

g, heavy roller should have enough weight, usually made of steel solid, coated with ink-friendly material, and should rely on the weight of the heavy roller itself to absorb vibration in the ink system.

h, reasonable layout of the structure space, easy to install and remove the ink roller, adjust the pressure and so on.

Makeup Eyelashes

Makeup Eyelashes,False Eyelashes,Fake Eyelashes,Magnetic Eyelashes

Guangzhou Yafei Makeup Toiletry Co.,Ltd , https://www.yfmakeupbrush.com