JPH043748B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to flexo printing machines, gravure printing machines,
The present invention relates to a device for supplying printing ink to an ink forming roller of a lithographic printing machine or the like.

[Conventional technology]

For example, when feeding printing ink onto an inking roller in a flexographic printing machine or a gravure printing machine, a rotating inking roller or pumping roller is dipped into an ink reservoir and the ink film picked up thereon is collected. It is known to press against an ink applicator roller and to drain the excess ink squeezed out back into the ink reservoir. Furthermore, in addition to the storage within the ink reservoir, an additional reservoir is used outside the ink reservoir, in which an ink pump is arranged to continuously pump printing ink into the ink reservoir. Inking devices are known in which excess ink is transported back by the weight of the printing ink. Ink applicator devices are also known in which the printing ink is delivered to an ink applicator roller by means of a distribution chamber or a guide path, as described, for example, in US Pat. No. 3,766,856 and DE 3,135,711. be. However, here too, the excess ink is pumped back by gravity into the reservoir with the ink circulation pump. In these systems, it is known to change the viscosity of the printing ink by adding solvents.

The mixing of the solvent into the printing ink takes place, depending on the print quality requirements, either directly into the ink fountain or in an ink reservoir connected to the ink fountain via a supply and return hose connection, in which case this ink is A pump present in the reservoir maintains continuous ink circulation between the ink fountain and the ink reservoir. With such ink circulation means and additional viscosity control devices, high quality requirements as well as uniformity requirements can be met.

[Problem to be solved by the invention]

However, in the case of these known devices, the energy consumption required for the evaporation of the solvent and the consequent environmental pollution as well as the high cost of cleaning the ink circulation system when changing the ink are particularly important. This is a serious disadvantage, especially considering that the low viscosities required for these ink circulation systems are not at all necessary to obtain good print quality.

Furthermore, an inking device is known in which, for example, in planographic printing, ink supplied with high viscosity is ground by a number of oscillating rollers and uniformly supplied onto an ink forming roller. In this case, a good rolling effect can only be achieved by a large number of rollers arranged one behind the other.

It is an object of the present invention to adjust the viscosity of the printing ink immediately before the delivery of the ink to the applicator roller by adding a small amount of solvent when uniformly feeding the printing ink onto an applicator roller, such as a mesh-faced roller. It is an object of the present invention to provide a device for supplying printing ink to an ink applicator roller, in which complete cleaning is achieved by rinsing with a relatively small amount of solvent when changing the printing ink.

[Means to solve the problem]

In order to achieve the above object, the device of the present invention for supplying printing ink to an ink form roller has a horizontally oscillating roller inside which can adjust the rotation speed and rotation direction independently of the orbital speed of the printing medium. a housing defining a cylindrical or substantially cylindrical ink chamber into which printing ink is fed, the printing ink being fed into the ink chamber in the form of a thin layer of printing ink on the surface of an ink applicator roller; The oscillating roller is provided eccentrically within the ink chamber so that the ink forming roller can be fed out, and the oscillating roller is provided eccentrically within the ink chamber, passes through the ink outlet opening of the housing, and adjusts to a certain viscosity within the ink chamber. two doctor knives for circumferentially circumferentially limiting an inking space through which the applied ink is delivered to the inking roller; and two sealing members for sealing off the inking space from the inking roller. It is provided.

[Effect]

This is an ink supply system that allows even highly viscous printing ink to be delivered from an ink storage tank through a closed ink chamber onto an ink form roller, and to evenly apply the ink. The pre-existing viscosity at the transition from the closed ink chamber to the ink applicator roller is regulated by the rotational speed of the oscillating roller provided in the closed ink chamber, and the pressure in this ink chamber as well as The amount of printing ink supplied can be controlled by changing the rotational speed of the pump used to transport the ink.

An ink pump is placed in the ink reservoir, preferably with exclusion of air, which transports the printing ink under pressure from the outlet of this pump via a mixing chamber and a closed ink chamber to the ink applicator roller. do. Here, centrifugal pumps can be used as well as gear pumps or flexible tube pumps.
In either case, the pump pressure and discharge amount can be controlled by selecting the pump rotation speed.
The printing ink is conveyed to the ink chamber through the supply conduit. Since the supply of printing ink is determined solely by the ink consumption, the cross-sectional area of this supply conduit can be designed with a diameter of only a few mm.

A cylindrical or nearly cylindrical ink chamber is provided with a horizontal swinging roller rotatably supported around a longitudinal axis, and the distance between this roller and the ink chamber wall surface can be adjusted. It is possible.

An ink outlet opening is provided in the housing of the ink chamber, facing the ink supply surface or at an angle thereto, through which the printing ink, adjusted to a certain viscosity by kneading, is delivered to the inking roller. It leads to a narrow ink application space for delivery. This inking space is closed on all sides and is demarcated in the circumferential direction of the inking roller by two doctor knives.

The viscosity of the printing ink present in the ink chamber is adjusted by the rotation speed of a transverse roller located in the ink chamber, which can be adjusted independently of the rotation speed of the ink form roller. The action of two influencing factors, namely shear force and temperature, results in a constant viscosity of the printing ink. This shearing force can be varied over a wide range by varying the circumferential speed of the oscillating roller and by varying the mixing gap (the distance from the ink chamber wall on the ink outlet side of the oscillating roller).

The temperature set in this case as a function of the shear force likewise influences the viscosity due to the temperature-plastic behavior that already exists in almost all flexographic and gravure printing.

According to the results of experiments conducted with high viscosity printing inks, 4.
It is shown that no reduction in ink viscosity is necessary until a typical viscosity value of about 25 seconds is reached in a feed cup with a mm diameter outlet.

A water-soluble inn with an exit time of 56 seconds from a 6 mm diameter supply cup was used, which printed with satisfactory quality at a rotation speed of 350 rpm of a 50 mm diameter oscillating roller in the ink chamber. was completed.

The thixotropic behavior of this printing ink could be confirmed by processing it in a stirring device. After stirring for 30 seconds, the viscosity decreased from 56 seconds to 21 seconds in run time.

A viscosity approximately similar to water is required because of the construction of conventional ink applicator systems in which the circulation of printing ink is maintained by gravity. The printing ink used in the embodiments described above is not able to freely flow back and exhibits a stagnation phenomenon, as experiments with conventional inking devices have shown. It was observed that clumps of printing ink were thrown out of the ink fountain.

The pressure in the ink applicator space can be adjusted by varying the rotational speed of the pump, thereby influencing the thickness of the ink layer on the ink applicator roller.

Since no further ink circulation takes place, the supplied printing ink can only flow out via the inking rollers, thereby making it possible to predetermine the amount of ink per printing pattern. .

The ink supply device according to the invention with forced supply of printing ink under adjustable pressure makes it possible to print with printing inks of high viscosity and therefore with very low solvent content. . This has the advantage of lower energy for drying the solvent and reduced emissions of solvent vapors.

Another advantage of the ink supply device of the invention is that the reaction time after the indication of a change in the color density value in the printed image until the change in the viscosity of the printing ink can be reduced to the order of a few seconds. .
This makes it possible to control the color density value by incorporating the speed of the oscillating roller as a manipulated variable. It is also possible to use the rotational speed of the ink pump and therefore its filling pressure as a further operating variable.

Furthermore, such a system can reduce its total ink filling space to values as low as 10 squared compared to conventional ink circulation systems, and thereby To enable cleaning by rinsing without requiring removal of an ink fountain.

Since the printing ink is circulated only within the ink chamber, only a relatively small amount of printing ink is present in the ink supply chamber. In order to prevent the risk of drying out during relatively long periods of dry operation, it is also possible in the case of the device according to the invention to replenish the amount evaporated from the ink applicator roller. The inflow can take place directly into the inking chamber in a known manner, controlled by the torque of the oscillating roller, or alternatively by spraying a corresponding amount of solvent directly onto the surface of the inking roller. It will be done. Another possibility for replenishing solvent during relatively long dry runs is to use one of the many supply channels or a part of them as a return channel,
The printing ink is drained back from these and replenishment is carried out in a known manner, provided that in this case too the volume of the ink reservoir is determined by the effective consumption per ink loss. That's true.

〔Example〕

The invention will now be described in detail with reference to some preferred embodiments shown in the accompanying FIGS. 1 to 4. FIG.

The device of FIG. 1 consists of an ink applicator roller 1 having an ink housing 2 and an ink chamber 5, within which is a transverse roller which can be selectively rotated about a longitudinal axis in both directions of rotation. 3 is provided.

This horizontal swinging roller 3 is driven so that the number of rotations can be varied.

The printing ink is pumped from a storage tank (not shown) into the ink chamber 5 via the ink supply opening 4 by means of an ink pump with variable rotational speed, preferably with exclusion from air. Centrifugal pumps as well as gear pumps or flexible tube pumps can be used here.
The ink supply opening 4 can also be designed as a slotted nozzle. Alternatively, a series of cylindrical perforations with a corresponding number of supply conduits may be inserted into the ink chamber 5.
It can also be used for ink supply.

The oscillating roller 3 is arranged in the ink chamber 5 with an adjustable eccentricity such that on the outlet side there is a narrower gap in front of the ink outlet opening 6 than on the outlet side. Its adjustment range is limited to a range from a position concentric with the ink chamber 5 to a point where it contacts the wall surface of the ink outlet opening 6.

The ink outlet opening 6 and the ink applicator space 7 are arranged at the necessary distance from the doctor knives 8 and 9 in order to keep the time between adjusting the position of the oscillating roller 3 and feeding the printing ink to the ink applicator roller 1 as small as possible. limited to the size required.

The inking space 7 is sealed in a known manner using a sealing member (not shown).

Doctor knives 8 and 9 are clamp members 10 and 1
1 is tightened and fixed to the housing 2 using tightening screws 12 and 13.

3 and 4 show a special embodiment of a spring-loaded sealing member. As the doctor knives 8 and 9 wear out, the position of the ink chamber 2 (housing 1) relative to the ink form roller 1 changes.
In this embodiment, the sealing of the side surface of the ink chamber 2 is configured so that each sealing member follows the change in position without causing a change in the pressing force, and in this case, the pressing force can be adjusted to a constant level. It's getting old.

Sealing member supports 14 are inserted into the swallowtail grooves 15 of the housing 2 on both sides of the housing 2 in the axial direction. The sealing element 17 is pressed in the direction of the screen roller 1 by a spring 16. A large number of obliquely arranged flat grooves 18 are provided on the sliding surface of the sealing member 17 with respect to the mesh surface roller 1, and these are pushed outward by the rotational movement of the mesh surface roller 1. A feeding effect is exerted on the printing ink to be applied in the direction towards the inking space 7, and an improved sealing effect is thereby achieved. Further, the sealing plate 19 allows printing ink or cleaning liquid to be applied to the sealing member support 1.
4 to prevent the ink from leaking out of the inking space 7.

Another simplification in the exchange of printing inks is that the liquid required each time, either printing ink or cleaning liquid, can be supplied by inserting the pipe through a sealing sleeve into the reservoir of either liquid. It is proposed that not only the printing ink but also its cleaning liquid be placed in a pressure chamber which is pressurized by air or gas so that it is pumped into the ink chamber. The pump pressure can be adjusted in a known manner by means of pressure reducing valves.

〔Effect of the invention〕

As explained above, the present invention provides a horizontal oscillation roller that is eccentrically provided in an ink chamber, and a narrow ink area formed between the ink chamber wall and the outer peripheral surface of the lateral vibration roller before delivering printing ink to the ink form roller. By adjusting the viscosity of the printing ink by grinding it in the mixing cavity, it is possible to print with a printing ink with a very low solvent content, resulting in lower drying energy of the solvent and less emission of solvent vapor. The advantage is that, when changing the printing ink, complete cleaning is achieved by rinsing with a relatively small amount of solvent.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view of an ink supply device according to an embodiment of the present invention, Fig. 2 is an enlarged view of its main parts, and Fig. 3
and FIG. 4 are a sectional view and a front view of the main parts of another embodiment of the present invention, respectively. 1... Ink form roller, 2, 2... Housing,
3... Horizontal swing roller, 4... Ink supply opening, 5... Ink chamber, 6... Ink outlet opening, 7... Ink application space, 8, 9... Doctor knife, 10, 11... Clamp member, 12, 13... Tightening screw, 14... Sealing member support body, 16... Spring, 17... Sealing member, 1
8...Groove, 19...Sealing plate.

Claims (1)

[Scope of Claims] 1. A device for supplying printing ink to an ink forming roller of a flexo printing machine, a gravure printing machine, a planographic printing machine, etc., which adjusts the rotation speed and rotation direction regardless of the orbital speed of the printing medium. A housing 2 has a lateral oscillating roller 3 therein and forms a cylindrical or nearly cylindrical ink chamber 5 into which printing ink is fed. arranged close to the inking roller 1 in such a way that printing ink can be delivered only in the form of a thin layer on the surface of the roller 1, said oscillating roller 3 being arranged eccentrically in the ink chamber 5; The ink forming space 7 is formed by the ink forming roller 1 for passing through the ink outlet opening 6 of the housing 2 and delivering the printing ink adjusted to a certain viscosity in the ink chamber 5 to the ink forming roller 1.
Two doctor knives 8, 9 are provided for circumferentially limiting the inking roller 1, and two sealing members are provided for sealing the inking space 7 with respect to the inking roller 1 in the axial direction thereof. A device that supplies printing ink to the applicator roller. 2. The device according to claim 1, wherein the hydraulic pressure and/or supply amount of printing ink in the inking space 7 can be changed by changing the rotational speed of an ink pump. 3. The apparatus according to claim 1 or 2, wherein the eccentricity of the oscillating roller 3 with respect to the ink chamber 5 can be adjusted from a concentric position to a position in contact with a wall surface. 4. The device according to any one of claims 1 to 3, wherein the ink supply opening 4 provided in the housing 2 to the ink chamber 5 can be used exclusively for supplying printing ink. . 5. Apparatus according to any one of claims 1 to 4, wherein at least one of the ink supply openings 4 can be used as an overflow opening or an ink return passage. 6. The sealing member has a number of flat grooves 18 arranged diagonally on the sliding surface with the inking roller 1, and these grooves enter the inking space 7 by the rotational movement of the inking roller 1. The patent claim consists of a sealing element 17 adapted to produce a transport effect of the printing ink in the opposite direction, the pressing force of the sealing element 17 on the inking roller 1 being provided by a spring 16. Range 1st to 5th
Apparatus according to any one of paragraphs. 7. The necessary transfer pressure for the printing ink or the cleaning liquid is generated in a pressure chamber supplied with air or gas, and the reservoirs for the printing ink and the cleaning liquid are passed through the transfer conduit through the sealing sleeve to the respective container. The ink cartridge according to any one of claims 1 to 3 is fitted into the pressure chamber so that the required liquid can be pumped into the ink chamber by being inserted into the ink chamber. The device described.