JPS62149447A - Ink supply system for flexographic plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel ink supply system for labels and other flexographic printing presses.

Several systems are known for supplying ink to the printed notes of flexo printing machines. The flexo stamp t'61 is used for printing flexible strips made of cellulose, transparent plastic, translucent or opaque materials.

Primarily in the halftone field, printing systems generally include one rubber roller with a peripheral edge partially immersed in the ink of an ink reservoir, a second roller with a mesh-like surface for ink transfer, and a third roller carrying a curved printing plate. Including rollers. The final roller acts as a back-up roller for resisting the printing pressure and supports f of the flexible strip to be printed.
I love all of you. The first two rollers are supported on the movable body by respective shafts.

Such a movable body can be moved relative to the printing plate carrying roller by means of a screw mechanism. The screw mechanism brings the surface of the mesh roller into contact with the surface of the curved printing plate.

In the case of halftone printing medium 11i11, a first roller (ink transfer roller) having a mesh-like surface, a second roller carrying a curved printing plate, and a backup roller are installed in the same manner as above, and carrying an ink container. The movement of the movable body can also be arranged by a ratchet mechanism.

In this case, instead of a rubber roller, a doctor blade is coupled to the reticulated ink transfer roller to ink up and separate excess ink from the surface of the roller. As a result, only the amount of ink exactly necessary for printing is transferred to the surface of the curved printing plate.

In both of the briefly described embodiments above, the ink transfer rollers both have a mesh-like surface.

The ink supply system for flexographic printing plates according to the invention is characterized, inter alia, by the use of a novel roller combination, in which a smooth working roller is mounted between the ink transfer roller and the printing plate carrying roller, as described below. It is.

The invention will be understood more fully from the following description based on a non-limiting example of an ink supply system for curved flexographic printing plates according to the invention.

In a conventional flexographic printing system for the monotonous field shown in FIG. 1, a first roller l has six flexible surfaces of rubber or another flexible material. The second roller 2 has a mesh-like surface which acts as an ink transfer roller.

The third roller 3 carries a curved printing plate 5. The final roller 4 functions as a backup roller and also receives the flexible strip 6 to be printed.

Each of these four rollers has mutually parallel horizontal shafts carried by corresponding supports, of which only seven supports of roller 3 are shown.

The roller l is partially immersed in the ink in the container 9 and is tangential to a screen 1''-shaped ink transfer roller 2 to which the ink image is transferred and transferred by the roller 2 to the curved printing plate 5. sent. The pressure between the marks (61 and roller IJ:2) can be adjusted to a suitable value.The rollers 1, 2 are supported by a box-shaped body 8, which carries a container 9, and the pressure between the rollers IJ and 2 can be adjusted to an appropriate value. The roller 2 is movable relative to the support 7 by means of a screw lO in order to bring the roller 2 as close as necessary to the roller 3 in order to supply ink to the curved printing plate 5 under the horn.

In the case of halftone printing (halftone printing) shown in the specific example in Figure 2,
A doctor blade 14 is used. The doctor blade 14 is primarily a stone-like member with straight edges tangential to the surface of the mesh roller 19 immersed in the ink of the container 9.

3 and 4 illustrate the ink supply system of the present invention including a roller assembly. In the illustrated roller assembly, a working roller 13, which has a smooth surface and is used for ink transfer, includes a roller 11 and a roller 12, and is mounted between a roller body 8 and a printing plate carrying roller 3.
This configuration provides special functions as described below to achieve the purpose of the present invention.

According to FIG. 3, the roller 11 with a mesh surface is
The surface of roller 1 is partially immersed in ink.
It is in contact with 2. Such a surface is made of rubber or other soft, smooth material and serves as an intermediate ink transfer roller. The third roller of the ink supply roller assembly, metallic smooth roller 13, is an ink transfer roller. Preferably, the surface consists of a smooth hard material, such as a ceramic material. This smooth roller 13 may have the same circumferential length as the roller 3 carrying the printing plate 5 or may have a different circumferential length.

The roller 3 carrying the printing plate 5 and the backup roller 4 are equivalent to the corresponding rollers 3, 4 of the prior art and have the same function.

The various roller adjustment systems operate as follows to obtain the required pressure between the opposing surfaces of the various rollers.

First, the pressure between the first roller 11 and the second roller 12 is adjusted to ;17.1, and then! Apply pressure to the assembly formed by these two rollers via a similar mechanism. The surface of the roller 12 is brought into contact with the surface of the roller 13 and then the roller assembly 11.12.13 is moved by a screw mechanism 17 or similar mechanism.
It is pressed against the plate 5 carried by the roller 3. The common support of the three rollers is indicated by reference numeral 16.

The synchronization of the rollers, ie the adjustment of their respective speeds +i, is carried out as follows. The roller 13 is driven by a gear fixed to its shaft. The gear engages with a second gear mounted on the shaft of the roller 3.

As a result, the circumferential speed of the roller I3 for the same length on the circumference matches the circumferential speed of the printing plate 5 carried by the roller 3. Roller 12 is driven by roller 13 via a variable speed pulley or any other suitable system that matches the circumferential speed of roller 12 to the circumferential speed of roller 13. However, it is preferable that the roller 12 and the roller I3 have mutually different circumferential speeds. In this case, roller 1
The circumferential speed of 2 (which is equal to or higher or lower than the circumferential speed of roller 13) can be adjusted without stopping the machine.

Further, the roller 12 may be driven by a mechanism different from that of the roller 13 (for example, a hydraulic variable speed motor or a speed regulating electric motor).

Also, after determining the ideal speed ratio between rollers 12 and 13, a gear wheel drives roller 13 via a second drive device coupled to the shaft of roller 13.

It is also possible to drive the rollers 12 using the same method. The ratio between the gear diameter and the diameter of the two rollers may be adjusted depending on the ratio to be maintained between the circumferential speeds of the two rollers. Adjust the appropriate speed ratio by various combination gears. In this case, replace the gear without stopping the hook.

After one or more modifications of the drive system, the roller 12 may rotate in the opposite direction to the roller 13, and it is also possible to set different circumferential speed relationships between the two rollers.

Similar considerations should hold true for rollers 11 and 12.

In order to prevent drying of the ink layer on the roller surface when the printing press is stopped, the rollers 11.12.13 are independent regardless of whether the rest of the machine is running or idling. The rotation can continue.

In the embodiment of FIG. 4, rollers 11, 12. I3 is mounted on the same movable support. In this embodiment, which is simpler than that in FIG. 3, the rollers 13 are in principle the same.

B of the ink layer on the surface of the roller? Ii is performed as follows. The viscosity of the ink is increased to 4.1 to increase the uniformity and thickness of the ink retention on the surface of the smooth roller 13! 11) and are adjusted by various variables as follows.

(a) Line (groove) failure per jam of the mesh roller 11, (h) Type of mesh surface of the l:7-ra 11, (
C) Pressure acting on rollers 11 and 12; (d) Pressure acting on roller 13 between rollers 11 and 12; (C) Ratio of circumferential speeds of rollers 11 and 12. The speeds of both rollers may be equal or different.

Cf) Ratio of circumferential speeds of roller 12 and roller 13. The speeds of both rollers may be equal or different.

(g) The rotational direction of the roller 12 with respect to the rotational direction of the roller 13 (same direction or opposite direction). A change in the rotational direction of the roller 12 causes a change in the rotational direction of the roller 11.

The advantage obtained by arranging the rollers as described above is that the amount of ink on the printing plate can be adjusted. This is an important condition for obtaining high quality prints with flexo printing systems. The printing plate's second ink layer must be uniform and also suitable for each case! It's important that it's seven-dimensional. Both variables (ink layer uniformity and thickness) are adjustable.rr! , the print quality improves further when the box is enlarged.

Furthermore, if it were possible to apply a thinner and more uniform layer of ink to the printing plate than currently known printing systems, it would be possible to print with a finer mesh on the printing plate. The biggest difficulty in printing with a dense mesh by increasing the number of lines per cm is that there is an excess of ink on the printing plate, and as a side effect, the ink invades the spaces formed by the lines of the mesh. .

The system of FIG. 2, which corresponds to the conventional procedure for halftone flexographic printing, uses a doctor blade to remove excess ink from the surface of the ink-soaked mesh roller, as described above. This allows only the required amount of ink to remain on the reticulated surface of the roller and to be transferred to the printing plate. However, this system has many limitations as follows. Namely: (a) The number of lines per cm that can be used on a reticulated surface is limited, and even modern rollers cannot exceed 160 lines per cm.

(b) The cost of a mesh roller with a large number of lines is high.

(C) Since the doctor blade exerts a certain amount of pressure on the surface of the roller, wear of the mesh roller is inevitable as a result of the action of the doctor blade.

((1) Due to the action of the doctor blade, the maintenance cost is high because it is necessary to prepare a worn mesh roller.

(c)l! /! ! Replace the worn roller with a gold roller roller assembly. This adds even more problems.

(r) A 1° second orb that adjusts the required amount of ink by j, 'il. Since one adjustment variable is the number of lines per cm of the mesh roller, rollers with different meshes, e.g. It is necessary to provide six lines and a large number of rollers, which results in a considerably high selling price.

(g) The roller that transfers ink to the printing plate is a mesh roller, and a small 't' that functions as an ink storage part.
Vt, the surface of the roller is not completely uniform even though the number of lines per cm is large. Therefore, the printing plate has a non-uniform surface to receive ink from the roller, so that the ink layer applied to the printing plate is non-uniform.

(h) In halftone printing when receiving ink from a mesh roller, a "moiré" effect may occur in all or part of the printing plate as a result of registration. Such a drawback is a serious problem since it is virtually impossible to completely eliminate it.

In many cases, even if a mesh roller is selected that appears to print properly, the process will not proceed accurately if a "moiré" effect occurs on all or part of the printing plate. In this case, to avoid such effects it is necessary to use a new mesh roller, which is not optimal for applying the required amount of ink.

According to the present invention, the above drawbacks are corrected for the following reasons.

(a) The surface of the roller 13, which transfers the ink to the printing plate, is smooth, thus eliminating all the disadvantages of using a mesh transfer roller. The ink layer is much more uniform than using a mesh roller and print quality is improved. With this type of roller, a thinner layer of ink is applied than with a mesh roller, so more precise halftone printing is possible.

Since the surface of the ink transfer roller is smooth, ie, has no mesh, no "moiré" effect occurs.

(b) In the case of the present invention, the first roller of the roller assembly, the reticulated roller 11, has one purpose;
The purpose of this is to transfer the brushed ink to the roller 12. This eliminates the need for high density (100 lines per cm is sufficient), thus reducing the cost of the rollers. obtain.

(C) We removed the doctor blade that acts on the surface of the roller immersed in the ink itself, lol! The wear life of the I eye is extended and the maintenance cost is reduced.

(d) Since the ink layer can be adjusted as described above, the ink layer applied to the printing plate can be adjusted to substantially 511 (increases) without using any printing unit elements as presently required. This means that the amount of ink applied to the printing plate can be easily adjusted, for example without using the mesh rollers of the prior art.Therefore, the operation is much easier, the adjustment capacity is high and the time required for adjustment is also reduced. be done.

(e) Since the amount of ink to be applied to the printing plate can be adjusted steplessly, the Z-required amount of ink can be adjusted positionally according to the requirements of various printing operations.

(f) If desired, the peripheral length of the smooth roller 13 is equal to the peripheral length of the printing plate carrying roller 3 including the printing plate, so that the printing plate can receive ink from the same area of the ink transfer roller. Therefore, the accuracy of ink application can be improved.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a conventional ink supply device normally used for halftone printing, Fig. 2 is an explanatory diagram of a conventional device used for halftone printing, and Fig. 3 is an explanatory diagram of a conventional ink supply device used for halftone printing. FIG. 1 is an explanatory diagram of another specific example of the device of the present invention. 1.2.3.4...Roller, 5...Printing plate, 6...Strip, 7...
・Support, 8...Mountain body, 9...Container, IO・
...The screw machine is also 1η, +1. +2.13・・・・・・
・Roller, 14...Doctor blade, 16...
...Support, 1st field 3rd trouble 84 mouth

Claims (4)

[Claims] (1) An ink supply system for a flexographic printing plate for supplying ink to a curved printing plate mounted on a carrier roller disposed between an ink supply roller assembly and a backup roller, the system comprising: one roller having a reticulated surface for collecting ink from the container in which the first roller is partially immersed and tangential to the flexible surface of the second roller, mounted on the same movable support; An ink supply system for a flexographic printing plate, characterized in that the contact pressure between the first roller and the second roller is adjustable, and the support further carries a third roller of the assembly having a smooth surface. (2) A third roller with a smooth, hard surface serves to transfer an ink layer of adjustable thickness to a printing plate carrying roller, both rollers being tangential to each other. An ink supply system for a flexographic printing plate according to claim 1. (3) A smooth third roller is attached to the support,
Ink supply system for a flexographic printing plate according to claim 1 or 2, characterized in that the support is movable relative to the supports of the other two ink supply rollers of the ink supply roller assembly. . (4) The length of the peripheral edge of the smooth and hard ink supply roller matches the length of the peripheral edge of the printing plate carrying roller including the printing plate, according to any one of claims 1 to 3. Ink supply system for flexographic printing plates as described.