DE29616686U1 - Device for coating substrates with a liquid - Google Patents

Description

MAN Roland Druckmaschinen AG Mühlheimer Str. 341 D-63075 Offenbach

Device for coating printing materials with a liquid

The invention relates to a device for coating printing materials with a liquid, preferably for at least one coating unit of a printing machine according to the preamble of the main claim.

A device of this type is known from EP 0 612 618 A2. The device is preferably combined with an offset printing machine and is essentially formed by a counter-pressure cylinder, a form cylinder carrying a rubber blanket, an application roller associated with the form cylinder and a chamber doctor blade adjacent to the application roller as a dosing system. The dosing system is assigned a supply line and a return line, which are coupled to a container for a coating liquid, e.g. paint. The supply line and return line have pumps, preferably peristaltic pumps, before and after the dosing system, which ensure the supply and return flow of the coating liquid. A first switching valve is arranged in the supply line for the coating liquid and is coupled on the line side to a container for receiving water. A second switching valve is arranged in the return line for the coating liquid and is coupled on the line side to a container for receiving waste. The device can be switched over via the valves for the supply of paint or for the supply of water for cleaning the device.

An ink circulation and washing system for a printing machine is known from US-PS 4 526 102. Two different inks can be fed from separate containers into a roller gap via a spout on the line side. The roller gap is formed by two parallel ink rollers (squeeze roller principle), with the ink rollers being assigned to a plate cylinder.

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are arranged. At the front, underneath the paint rollers, there are collecting trays, which connect a switching valve to the corresponding container for the respective color on the line side via return lines. The paint returns to the corresponding collecting containers using the principle of gravity. Cleaning fluid can be fed into the supply lines and return lines via a separate feed line via several switching valves. The disadvantage of devices that work according to the principle of gravity is that when processing quickly drying media (paint, varnish), this circulation principle clogs the lines and can therefore only be used for special media. Another disadvantage is that even in cleaned components (lines, pumps), residues of the original coating liquid can still adhere. There is a risk that different types of coating liquid can mix with one another. This can lead to residues, e.g. lumps, forming within the device if chemically incompatible liquids are introduced into this circulation system one after the other.

The object of the invention is to noticeably avoid possible residues when changing orders in the device and to reduce the changeover times and the cleaning time in the circulation system.

According to the invention, the object is achieved by the design features of claims 1 and 10.

A coating device is essentially formed by a counter-pressure cylinder, an adjacent form cylinder with at least one associated application roller and a metering system that can be switched on and off from the application roller. The metering system can optionally be formed by a chamber doctor blade with an application roller as an anilox roller or a trough for the coating liquid with a scoop roller and metering roller or a metering roller with supply of the coating liquid via the roller gap, which is formed by the metering roller and application roller.

In addition to the dosing system, two separate circuits are preferably provided for

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Different coating liquids are assigned as a circulation system.

With the device according to the invention, residues are noticeably avoided, since mixing of different coating liquids cannot take place or is noticeably reduced. The changeover times are limited only to exchanging the respective dosing systems and the washing times are shortened, since the washing intervals can be extended.

The coating liquids are stored in reservoirs which can be pre-selected, preferably by a central control system, and activated by means of pumps. This allows the required coating liquid to be assigned to the selected dosing system in conjunction with the corresponding circuit.

Water-based dispersion varnishes, liquid printing inks with and without metal pigments or UV varnishes are particularly suitable as coating liquids.

The invention will be explained in more detail using an embodiment.

Showing:

Fig. 1 a device for coating with two circuits,

Fig. 2 two devices for coating,

Fig. 3 a device for coating with a main and a

Bypass circuit

Fig. 4 two devices for coating with a main and

a bypass circuit

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A multi-color offset printing machine has a downstream device for coating printing materials in the direction of sheet travel, which is designed here as an inline varnishing unit (Fig. 1). The device according to the invention essentially consists of a sheet-guiding impression cylinder 2, to which a forme cylinder 3 is assigned. Depending on the print job, the forme cylinder carries a rubber blanket or, for example, a flexible letterpress plate. An applicator roller 4 can be switched on and off relative to the forme cylinder 3. An applicator roller 4 that can be switched on and off is assigned adjacent to the applicator roller 4. The applicator system 5 can be either a chamber doctor blade with a screened applicator roller 4 or a dosing roller

&iacgr;&ogr; to form a dosing gap common to the application roller 4 as a so-called two-roller system. The two-roller system can be designed as a scoop roller immersed in a tub of coating liquid with an adjacent application roller 4 (scoop or dip roller principle) or as a dosing roller forming a roller gap parallel to the application roller 4 (squeeze roller principle).

Two separately controllable circuits 6, 14 are assigned to the individual dosing system 5. (Fig. 1 and 2). The first circuit has a liquid reservoir 11, e.g. for holding water-based dispersion paint. A feed line 7 is coupled to the liquid reservoir 11 and has an intermediate feed pump 9. The feed line 7 is coupled to the dosing system 5 in use.

If the dosing system 5 is a chamber doctor blade, the feed line 7 is fed into the middle of the chamber housing from above. If the dosing system 5 is equipped with a scoop roller, the feed line 7 is fed into the tank for receiving the coating liquid (scoop roller principle). If the dosing system 5 is designed with a dosing roller which forms a roller gap with the application roller 4 (squeeze roller principle), the feed line 7 is fed into the roller gap from above.

A return line 8 belonging to the first circuit 6 leads from the dosing system 5 to the liquid reservoir 11 with an intermediate suction pump 10

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back. If the dosing system 5 is a chamber doctor blade, the return line is arranged on the lower part of the housing. If the dosing system 5 is equipped with a scoop roller, the return line 8 is connected to the underside of the tub (scoop roller principle). If the dosing system 5 is designed as a dosing roller and application roller (squeeze roller principle), the return line is connected below, e.g. to a collecting tub.

The second circuit 14 is coupled to the dosing system 5 in use in the same way as the first circuit. The circuit 14 has a liquid reservoir 19, e.g. for holding UV varnish. UV varnishes are essentially dissolved acrylic resins that only dry under UV irradiation. A feed line is coupled to the liquid reservoir 19 and has an intermediate feed pump 17. The feed line 15 is coupled to the dosing system 5. From there, a return line 16 with an intermediate suction pump 18 leads back to the liquid reservoir 19. In further developments, a cleaning fluid reservoir 12 and/or a mixture reservoir 13 can be integrated into the line side of the first circuit 6 using switching valves (without reference numerals). This also applies analogously to the second circuit 14. Here, a cleaning fluid reservoir 20 and/or a mixture reservoir 21 are connected on the line side by means of switching valves (without reference numerals).

The dosing system 5 can thus be supplied either via the first circuit 6 with the dispersion varnish (as the first coating liquid) from the liquid reservoir 11 or via the second circuit 14 with the UV varnish (as the second coating liquid) from the liquid reservoir 19.

In Fig. 2, two coating devices are arranged one after the other as double coating units in the direction of sheet travel. Each coating device is formed by a counter-pressure cylinder 2 or 2', an associated forme cylinder 3 or 3', an application roller 4 or 4' adjacent to the forme cylinder 3, ^3J , and a metering system 5 or 5' that can be brought into contact with the application roller 4 or 4'. The forme cylinder 3 carries a flexible letterpress plate and the forme cylinder 3' carries a rubber blanket. The first metering system

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System 5 has circuits 6, 14 analogous to Fig. 1. Liquid reservoirs 11, 19 are assigned to circuits 6, 14. Reservoir 11 holds a water-based gold lacquer and reservoir 19 holds a dispersion lacquer.

In the conveying direction after the feed pump 9, a switching valve 23 coupled to a bypass line T is arranged in the feed line 7. The bypass line T leads to the second dosing system 5 ¹ . In the conveying direction before the suction pump 10, a switching valve 24 coupled to a bypass line 8' is arranged in the return line 8

&iacgr;&ogr; arranged. In the conveying direction after the feed pump 17, a switching valve 25 coupled to a bypass line 15' is arranged in the feed line. The bypass line 15' also leads to the second dosing system 5'. In the conveying direction before the suction pump 18, a switching valve 26 coupled to a bypass line 16' is arranged in the return line 8. The bypass line 16' leads back into the liquid reservoir 19 and the bypass line 8' leads back into the liquid reservoir 11.

This means that the dosing systems 5, 5' can be optionally switched to be supplied with the first coating liquid (gold lacquer) via circuit 6 and with the second coating liquid (dispersion lacquer) via circuit 14 through reservoirs 11, 19.

By appropriately controlling the switching valves 23 to 26, for example, the dosing system 5 can be supplied with the first coating liquid from the reservoir 19 via the circuit 14 and the dosing system 5' can be supplied with the second coating liquid from the reservoir 11 via the bypass lines T, 8'.

Fig. 3 shows another device. Analogous to Figure 1, two liquid reservoirs 11,19 are arranged to hold different coating liquids. For example, the liquid reservoir 11 holds a water-based dispersion varnish and the liquid reservoir 19 holds a flexographic printing ink. The feed line 7 leads from the liquid reservoir 11 via the intermediate feed pump 9 to the dosing system 5. From the dosing system 5

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leads a return line 8 with an intermediate suction pump 10 back into the liquid reservoir 11. This corresponds to the circuit. From the liquid reservoir 19, the feed line 15 with an intermediate feed pump 19 leads via a switching valve 27 arranged at the connection point into the feed line 7 to the dosing system 5. In the return line 8, a switching valve 28 is arranged at a connection point to the return line 16, whereby the return line 16 coupled to the liquid reservoir 19 in turn has a suction pump 18 in the conveying direction.

&iacgr;&ogr; This means that the dosing system 5 can be switched to supply the dispersion varnish or the flexographic printing ink. Any necessary cleaning or possible printing form change on the forme cylinder 3 will not be discussed in detail.

The design can also be transferred to two coating devices arranged one after the other as double coating units with a first circuit 6 (see Fig. 4).

According to Fig. 4, the coating devices are constructed analogously to Fig. 2. The forme cylinder 3 carries, for example, a rubber blanket and the forme cylinder 3' a flexographic printing plate. The first dosing system 5 has the circuit 6, which starting from the liquid reservoir 11 in the conveying direction after the feed pump 9 has the switching valves 23 and 27 within the feed line 7 and in the return line 8 has the switching valves 28 and 24 with suction pump 10. In the circuit 6, starting from the second liquid reservoir 19 in the conveying direction after the feed pump 17, the feed line 15 leading to the switching valve 27 can be coupled into the feed line 7 via the switching valve 25. Furthermore, in the return line 8 of the circuit 6 at the switching valve 28, the return line 16 leading to the reservoir 19 can be coupled via the switching valve 26.

At the switching valve 23, the bypass line T branches off to the dosing system 5' of the second coating device and at the switching valve 27', the bypass line 15' coming from the liquid reservoir 19 can be coupled in. The bypass line 8' leading back from the dosing system 5' branches off at the switching valve 28' into the

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Switching valve 24 into the bypass line 8' leading to the reservoir 11 and into the bypass line 16' leading to the reservoir 19 via the switching valve 26.

This means that the dosing systems 5,5' can be optionally switched to be supplied with the first coating liquid via the circuit 6 and with the second coating liquid via the bypass lines 7',8' through the reservoirs 11,19.

By appropriately controlling the switching valves 23 to 26 and 27, 28 or 27', 28', for example, the dosing system 5 can be supplied with the coating liquid from the reservoir 11 via the circuit and the dosing system 5 ¹ can be supplied with the coating liquid from the reservoir 19 via the bypass lines 7', 8'. Likewise, the dosing system 5 can be supplied with the coating liquid from the reservoir 19 via the circuit 6 by switching and the dosing system 5' can be supplied with the coating liquid from the reservoir 11 via the bypass lines 7', 8'.

The device according to the invention is not limited to the design with two liquid reservoirs 11,19. Rather, three or more liquid reservoirs can also be integrated into the circuits 6 and/or 14 by means of additional switching valves in a modular arrangement.

The mode of action is as follows:

If the printing material is to be coated with a first liquid, e.g. a dispersion varnish (water-based), the feed pump 9 feeds the liquid from the reservoir 11 via the feed line 7 to the dosing system 5 in use. The dosing system 5 coats the printing material with the liquid via the application roller 4 and the printing form on the forme cylinder 3. Excess liquid is fed back from the dosing system 5 via the return line 8 through the suction pump 10 in the first circuit 6 to the reservoir 11 (see Fig. 1).

If the substrate is to be coated with a second liquid, e.g. a flexographic printing ink, only the dosing system 5, application roller 4

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and to clean the printing form on the form cylinder 3. The first circuit 6 is decoupled from the dosing system 5. Depending on the print job, the dosing system 5 and application roller 4 (chamber doctor blade or two-roller system) as well as the printing form (flexible letterpress or planographic printing form) can also be exchanged. The second circuit 14 is coupled to the dosing system 5 selected for use. The second liquid is supplied from the liquid reservoir 19 via the supply line 15 with the feed pump 17 activated to the dosing system 5. Excess liquid is pumped from the suction pump 18 to the reservoir 19 via the return line 16.

If the device according to the invention is coupled to a cleaning device, the first circuit 6 is rinsed from a switchable cleaning fluid reservoir 12, e.g. with water. The mixture of first fluid and cleaning fluid can be switched from the circuit into a mixture reservoir 13 and from there, depending on the degree of saturation, used in circuit 6 for pre-cleaning or disposed of. Analogously, the cleaning fluid reservoir 20 can also be switched into the second circuit 14 and the mixture of second fluid and cleaning fluid can be switched into a mixture reservoir 21.

If two coating devices (Fig. 2) are arranged one after the other, the mode of operation is analogous to that shown in Fig. 1, for example, except that the bypass lines T and 8' are coupled to the first circuit 6 and the bypass lines 15' and 16' are coupled to the second circuit 14 via the switching valves 23 to 26. This applies to the liquid as well as the cleaning fluid supply.

If a coating arrangement (Fig. 3) is designed with a circuit 6 for a first liquid (reservoir 11) and a supply line 15 and a return line 16 for a second liquid (reservoir 19), then after cleaning the first circuit 6, the second liquid from the reservoir 19 is switched on via the switching valves 27, 28 into a sub-section of the circuit 6.

The selection of the respective circuits 6,14, the reservoirs 11-13, 19-21 and the

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The switching valves 23 - 28 and the pumps 9,10,17,18 are activated from a control system, preferably a control station.

In the design according to Fig. 1, mixing of different coating liquids when used alternately is excluded, since separate circuits 6,14 are present.

This is analogously the case in the design according to Fig. 2, since the bypass lines 7', 8' are integrated into the circuit 6. The bypass lines 15', 16' are correspondingly integrated into the circuit 14.

In the design according to Fig. 3 and 4, only one part of the circuit is flowed through by different liquids. This is advantageous, for example, in confined spaces. The only risk here is within the part of the circuit that a liquid will mix with residues from the previously processed liquid. However, this can be prevented by specifically cleaning the supply and return lines 7, 8. The effort required to clean the pumps is reduced because only the selected pumps 9, 10, 17, 18 need to be cleaned.

If the dosing system 5 is assigned a tray or a collecting plate for excess coating liquid, then preferably only one drain is provided, which is coupled to the active return line 8 or 8' or 16 or 16'. A simple measure is, for example, turning the plate or tray by at least 90° or replacing the tray so that the drain can be coupled to the corresponding return line. Alternatively, a sensor can be arranged on the tray or the collecting plate, which releases the drain or the respective return line for operation by coupling it to the control system.

From the central control system, e.g. a control station, the respective coating liquid is optionally allocated - via the corresponding circuit 6,14 or the bypass lines 7',8' or 15', 16' - from the respective reservoir 11,19 to the corresponding dosing system 5,5'.

11 Transfer cylinder f MAN 1
IRELAND Impression cylinder List of reference symbols Form cylinder 1 Application roller 2 Dosing system 3 first circuit 4 Supply line 5 Bypass line (supply line) 6 Return line 7 Bypass line (return line) T Feed pump 8th Suction pump 8th' Liquid reservoir 9 Cleaning fluid reservoir 10 Mixture reservoir 11 second circuit 12 Supply line 13 Bypass line (supply line) 14 Return line 15 Bypass line (return line) 15' Feed pump 16 Suction pump 16' Liquid reservoir 17 Cleaning fluid reservoir 18 Mixture reservoir 19 drip tray 20 23-28 Switching valve 21 22

Claims (13)

Protection claims 1) Device for coating printing materials with a liquid, preferably preferably for at least one coating unit of a printing machine, formed by a counter-pressure cylinder, a forme cylinder, at least one application roller with an associated adjustable dosing system and a circulation system for the liquid,
characterized, &iacgr;&ogr; that the dosing system (5) has two separately controllable liquid circuits (6, 14), whereby - the circuit (6) for a first liquid through a liquid reservoir (11), a supply line (7) coupled to the reservoir (11) with an intermediate feed pump (9) to the dosing system (5), a return line (8) from the dosing system (5) to the reservoir (11) with an intermediate suction pump (10) and - the circuit (14) for a second liquid is formed by a liquid reservoir (19), a feed line (15) coupled to the liquid reservoir (19) with an intermediate feed pump (17) to the dosing system (5), and a return line (16) from the dosing system (5) to the reservoir (19) with an intermediate suction pump (18). 2) Device according to claim 1 or 10,
characterized, that a cleaning fluid reservoir (12) is arranged in the circuit (6), which is coupled to the supply line (7) and the return line (8) by separate connecting lines and switching valves. 3) Device according to claim 1 and 2 or 10,
characterized, that a mixture reservoir (13) for receiving cleaning fluid and liquid is arranged in the circuit (6), which is coupled to the supply line (7) and the return line (8) by separate connecting lines and switching valves. 4) Device according to claim 1, &iacgr;&ogr; characterized by that a cleaning fluid reservoir (20) is arranged in the circuit (14), which is coupled to the supply line (15) and the return line (16) by separate connecting lines and switching valves. 5) Device according to claims 1 and 4,
characterized, that a cleaning fluid and liquid-receiving mixture reservoir (21) is arranged in the circuit (14), which is connected to the supply line (15) and the return line by separate connecting lines and switching valves (16) is coupled. 6) Device according to claim 1, characterized, that the circuits (6, 14) are coupled to a further dosing system (5') via bypass lines (7', 8', 15', 16'), wherein a switching valve (23) coupled to the bypass line (7') is arranged in the feed line (7) downstream of the feed pump (9), a switching valve (24) coupled to the bypass line (8') is arranged in the return line (8) upstream of the suction pump (10), in the feed direction downstream of the feed pump (17) a switching valve (25) coupled to the bypass line (15') is arranged in the supply line (15) and a switching valve (26) coupled to the bypass line (16') is arranged in the return line (8) in front of the suction pump (18) in the conveying direction. 7) Device according to claim 1 and/or 6 or 10, characterized in that that the dosing system (5, 5') is a chamber doctor blade and a screened application roller (4,4'). 8) Device according to claim 1 and/or 6 or 10, characterized in that that the dosing system (5, 5') is formed by a trough for receiving a liquid, a scoop roller immersed in the liquid and a dosing roller adjacent to the application roller (4 or 4'). 9) Device according to claim 1 and/or 6 or 10, characterized in that that the dosing system (5, 5') is formed by a dosing roller adjacent to the application roller (4 or 4') with a liquid supply for the roller gap. 10) Device for coating printing materials with a liquid, preferably for at least one coating unit of a printing press, formed by an impression cylinder, a forme cylinder, at least one application roller with an associated dosing system that can be switched on and off, and a liquid circulation system,
characterized,
that the dosing system (5) is assigned a controllable liquid circuit (6), the circuit (6) for a first coating liquid being connected to a liquid reservoir (11), a feed line (7) coupled to the liquid reservoir (11) with an intermediate feed pump (9) to the dosing system (5), a return line (8) from the dosing system (5) to the liquid reservoir (11) with an intermediate suction pump (10) and - that the circuit (6) is assigned a feed line and a return line (15, 16) which are coupled to a second liquid reservoir (19) for a second coating liquid and in the feed line (15) in the conveying direction a feed pump (17) and at the connection point of the feed line ♦ · lines (7 and 15) a switching valve (27) is arranged and in the return line (16) in the conveying direction a suction pump (18) is arranged and at the connection point of the return lines (8, 16) a switching valve (28) is arranged. 11) Device according to claim 10, characterized, that the liquid circuit (6) is coupled via bypass lines (7', 8', 15', 16') to another dosing system 5', whereby - in the conveying direction after the feed pump (9) in the feed line (7) there is arranged a switching valve (23) coupled to the bypass line (7 ¹ ), - a switching valve (24) coupled to the bypass line (8') is arranged in the return line (8) upstream of the suction pump (10) in the conveying direction, - in the conveying direction, a switching valve (25) coupled to the bypass line (15') is arranged in the feed line (15) downstream of the feed pump (17), - in the conveying direction, a switching valve (26) coupled to the bypass line (16 ¹ ) is arranged in the return line (16) upstream of the suction pump (18), and - in the conveying direction after the pumps (23,24), the bypass line (15') can be coupled to a switching valve (27') with the bypass line (7') leading to the dosing system (5'), and - in the conveying direction upstream of the pumps (25, 26) at a switching valve (28') the bypass line (16') branches off from the bypass line (8') and can be coupled into the return line (16) at the switching valve (26). 12) Device according to claim 10,
characterized, that the circuit (6) is assigned a cleaning fluid reservoir (20), which is coupled to the supply line (15) and the return line (16) by separate connecting lines and switching valves. 13) Device according to claim 10 and 12, characterized in that the circuit (6) is assigned a mixture reservoir 21 which receives cleaning fluid and liquid and which is coupled to the supply line (15) and the return line (16) by separate connecting lines and switching valves.