HK1109884A - Method and apparatus for metering a printing fluid,printing press and system having the apparatus and method for driving a pump - Google Patents

Description

Method and device for metering printing technology liquid

Technical Field

The invention relates to a method and a device for metering printing technology liquids. The invention also relates to a driving method for driving a pump by driving a fluid, closely related to the dosing method.

Background

The invention is based on the following background: by printing technology liquid is understood a coating liquid for printing a printing material and an auxiliary liquid for supporting the printing process. Coating liquids are, for example, printing inks and printing varnishes. The auxiliary liquid is, for example, a dampening solution, which supports the printing of offset printing inks. The printing technology liquid may also be a paste, as is the case, for example, in offset printing inks.

In printing presses which consume large quantities of printing technology liquid, the printing technology liquid is stored in a storage tank which is arranged vertically next to the printing press. The printing technology liquid is transported from the storage tank to its point of use in the printing press by a transport device. The delivery device comprises a volumetric pump for pumping a determined volume of printing technology liquid per unit time, i.e. a metered amount of printing technology liquid. For example, in the case of a printing press having a varnishing unit, a varnish tank is erected next to the varnishing unit, from which varnish is pumped into the varnishing unit by means of a pump.

DE 2625850 a1 describes a delivery device for delivering printing ink, which comprises a tandem cylinder with two pistons connected by a piston rod. A piston is loaded with compressed air which is used as the driving fluid. Thereby causing another piston to force printing ink out of the ink jacket. The disadvantage here is that external energy, in this case compressed air, must be supplied.

DE 19632717C 2 and DE 19953324a1 constitute further prior art.

Disclosure of Invention

It is therefore an object of the present invention to provide a further method for metering printing technology liquids and to provide a device suitable for carrying out the method.

This object is achieved by the method according to the invention and the device according to the invention.

The method according to the invention for metering printing technology liquids by means of a pump is characterized in that the pump is driven by the printing technology liquid. That is, no external energy in the form of compressed air is required to drive the pump.

In a development of the method according to the invention, the printing technology liquid is a printing ink or varnish. In a further refinement, the pump is a piston pump. In a further refinement, the metering volume of the printing technology liquid is determined by counting, by means of a control device, the number of piston strokes of the piston pump which is proportional to the metering volume. In a further development, the piston is acted upon with the printing technology liquid by a multi-way valve, which is controlled by the control device by means of control signals and these control signals are counted by the control device.

The device according to the invention for metering printing technology liquid comprises a pump, and is characterized in that the pump is driven by the printing technology liquid.

In a further development of the device according to the invention, the printing technology liquid can also be printing ink or varnish and the pump can be a piston pump. In a further development, the piston pump has pistons and a control device is provided for counting the number of piston strokes in proportion to the metered volume of printing technology liquid. In a further refinement, the piston is acted upon by a printing technology liquid via a multi-way valve and the control device is designed for controlling the multi-way valve by means of control signals and for counting these control signals.

The invention also relates to a printing press equipped with a metering device according to the invention or corresponding to a further development.

Also according to the invention, a system is provided which comprises a first ink fountain, a second ink fountain and a common supply device for supplying printing liquid to the first ink fountain and the second ink fountain, wherein the common supply device is connected to the first ink fountain by a metering device according to the invention or a development and to the second ink fountain by a further metering device which is likewise according to the invention or a development.

In a development of the system, the common supply device comprises a storage tank for storing the printing technical liquid and a delivery pump for pumping the printing technical liquid. In a further development of the system, the system comprises a first printing press in which the first ink fountain is arranged, and a second printing press in which the second ink fountain is arranged.

The invention also relates to a method for driving a pump by means of a drive fluid, characterized in that a printing liquid is used as the drive fluid.

In a development of the method, the pump can be a piston pump and the printing technology liquid can be printing ink or varnish.

Drawings

Further structurally and functionally advantageous refinements of the invention emerge from the following description of the preferred embodiments and from the drawings. Shown in the attached drawings:

fig. 1 shows a system, which includes a plurality of printing presses,

fig. 2 a dosing device, with which each printing press in fig. 1 is equipped,

figure 3 a first embodiment of the piston pump of the dosing device of figure 2,

figure 4a modification of the first embodiment of figure 3,

fig. 5 a second embodiment of a piston pump of the dosing device of fig. 2.

The structural parts and elements corresponding to each other in fig. 1 to 5 are denoted by the same reference numerals.

Detailed Description

Fig. 1 shows a machine system comprising a first printing press 12 and a second printing press 13. The printing presses 12, 13 are sheet-fed printing presses for offset printing. Each printing machine 12, 13 comprises at least four printing units, which each also comprise an ink duct. A first ink fountain of the printing mechanism of the first printing machine 12 is denoted by 7 and a second ink fountain of the printing mechanism of the second printing machine 13 is denoted by 8.

A metering device 6 is associated with the first ink fountain 7 and an identical metering device 6 is associated with the second ink fountain 8. These metering devices 6 are connected to a storage tank 10 by a pipe system 14 by means of a delivery pump 11. The reservoir 10 and the delivery pump 11 together form a supply device 9 for supplying a defined printing ink, for example black printing ink, to the supply ducts 7, 8. One such feed device is present for each printing ink black, cyan, magenta and yellow required for four-color printing, of which only two such feed devices are shown by way of example in fig. 1.

The storage container 10 is a storage tank in which the respective printing inks for all printing presses 12, 13 are stored. The feed pump 11 pumps printing ink out of the reservoir 10 and thereby places the printing ink under hydraulic pressure in the section of the line system 14 that is downstream of the feed pump 11. Since the printing inks are printed in the printing presses 12, 13, they are referred to below as printing technology liquids 1.

Fig. 2 shows the arrangement of the metering device 6 by way of example for a first ink fountain 7 and the metering device 6 assigned to it. The illustrated dosing device 6 is housed in a retaining device 16 designed for selectively housing the dosing device 6 and a cylinder (not shown in the figures). The cylinder is inserted into the holder 16 when print application is performed with a low ink consumption, and the metering device 6 is inserted into the holder when print application is performed with a high ink consumption.

The holding device 16 is mounted on a carriage 17 which is movable along a rail 18. The rail 18 extends parallel to the axis of rotation of an ink fountain roller 19 associated with the ink fountain 7. A metering device 6 arranged above the ink fountain 7 meters the printing liquid 1, i.e. the printing ink, in drops or jets into the ink fountain 7 or onto the ink fountain roller 19. The movement of the holding means 16 is controlled by the electronic control means 3. Control signals are indicated by reference numerals 20, 21 and 22, which are received and transmitted by the control device 3.

Fig. 3 shows a detail of the dosing device 6, wherein it can be seen that the dosing device 6 comprises a pump 2 and a multiplex valve 5 for controlling the pump 2. The pump 2 is a piston pump, more precisely an axial piston pump, which has a cylinder and a piston 4 which can be moved in the cylinder. The control device 3 (fig. 2) switches the multiplex valve 5 by means of a control signal 21 alternately into the valve slide position adjusted according to fig. 3 and into a further valve slide position, as symbolized by an arrow 23. By means of the cyclical switching of the multiplex valve 5, the pump chambers located in front of the piston 4 and the pump chambers located behind the piston 4 are alternately connected to the line system 14 and are alternately connected to the outlet 24.

In the valve core position of the multiplex valve 5 shown in fig. 3, the pump chamber located in front of the piston 4, i.e. the pump chamber on the right in fig. 3, is connected to the line system 14 and thus to the supply device 9, so that the printing technology liquid 1 hydraulic pressure generated in the line system 14 by the feed pump 11 (fig. 1) acts on the side of the piston 4 on the right in fig. 3 and moves the piston in the direction indicated by the arrow 25. Whereby the right-hand pump chamber is enlarged and it is filled with a gradually increasing volume of printing technology liquid 1. At the same time, the piston 4 displaces the printing fluid out of the left-hand pump chamber, which is connected in the illustrated position of the valve slide via the multi-way valve 5 to the outlet 24, so that the printing fluid 1 exits the left-hand pump chamber on the way into the ink fountain 7 (fig. 2).

The pump 2 is equipped with sensors 26 for detecting the two end positions of the piston 4. The corresponding sensor 26 sends a signal to the control device 3 by means of the control signal 20 (fig. 2): the piston 4 has reached the corresponding end position. The control device 3 is thus signaled when the piston 4 has reached its end position to the left in fig. 3. Depending on the control signal 20 of the respective sensor 26, the control device 3 switches the multi-way valve 5 by means of the control signal 21 into its other valve position, which is not shown in fig. 3.

In this further valve core position, the pump chamber located behind the piston 4, i.e. the pump chamber on the left in fig. 3, is connected to the supply device 9 and is acted upon by the hydraulic pressure of the printing technology liquid 1 from the supply device 9. The piston 4 is thus now displaced in the direction opposite to the arrow 25, whereby the piston 4 displaces printing technology liquid 1, which was contained in the pump chamber located in front of the piston 4 in the preceding cycle, i.e. the pump chamber on the right in fig. 3, out of the pump chamber and is pumped to the outlet 24. The end of this cycle is detected by a further sensor 26 and signaled to the control device 3, which thereupon switches the multiplex valve 5 again.

The control means 3 count, by means of the sensor 26, the number of strokes performed by the piston in the direction indicated by the arrow 25 and in the opposite direction. The number of strokes is proportional to the metered volume entering the ink fountain 7 through the outlet 24. The control device 3 informs the central machine control 15 (fig. 2) of the metering volume by means of a control signal 22. In this way the machine controller 15 obtains information about the specific ink consumption of the printing mechanism.

Since the displacement volume of the pump 2 is known, the sensor 26 can be dispensed with and the control signals 21 can be used instead directly to measure the consumption of the printing technology liquid 1, by means of which control signals 21 the multiplex valve 5 is switched. In this case, the control device 3 counts the control signals 21, the number of which is proportional to the number of stroke movements of the piston 4 and thus to the total quantity of printing technology liquid 1 fed into the ink fountain 7 as a result of these stroke movements.

It is important that the pump 2 not only delivers the printing technology liquid 1, but is itself driven by the printing technology liquid 1. This results in a number of advantages: no external energy, such as compressed air, is required to drive the pump 2. Furthermore, the metered liquid volume can be measured without difficulty.

A further advantage is shown in the event of a malfunction, in which case the metering device 6 of the first printing unit 12 malfunctions. In the event of such a malfunction, the feed pump 11 can continue to operate in order to pump the printing technical liquid 1 to the metering device 6 of the other, i.e. second printing unit 13, without the risk of the printing technical liquid 1 flowing out of the metering device 6 of the defective first printing unit 12 and causing harmful consequences in the first printing unit 12. Such a malfunction can occur, for example, in the event of a disturbance of the control signal 21 or in the event of a blocked switchover of the multi-way valve 5. In the event of such a malfunction, the piston 4 executes only a single stroke movement and the piston 4 remains in its end position reached by this stroke movement. Although the defective metering device 6 is always acted upon by the hydraulic pressure of the printing technology liquid 1, which is generated by the supply device 9 that continues to operate for the supply of further printing presses, there is no risk of the printing technology liquid 1 flowing out of the defective metering device 6. The retention of the piston 4 in its end position by the structurally defective dosing device 6 ensures that: the pump 2 comprising the piston 4 does not pump excess printing technology liquid 1 into the ink fountain 7 and the ink fountain does not overflow. The pumping of the pump 2 is automatically discontinued when there is a defect.

This risk exists if instead of the dosing device 6, a dosing device according to the prior art from DE 19953324a1 is connected to the common supply 9: if the common feed 9 continues to operate despite a malfunction of one of the metering devices, for example if the outlet valve of the metering device malfunctions, printing ink flows out of the other metering device which is not defective. When using the metering devices of the prior art, it is therefore necessary to stop not only the printing press whose metering device is defective, but also other printing presses which are also supplied with printing ink by the common supply 9, if such a defect occurs.

Such unnecessary machine down time is avoided by using the dosing device 6 of the present invention.

Fig. 4 shows a modification of the pump 2 shown in fig. 3. While in the pump 2 shown in fig. 3 the piston 4 is a piston without piston rods, the piston 4 in the variant shown in fig. 4 has two piston rods whose cross-sectional areas are equally large as one another, so that the pump 2 also constitutes a so-called synchronous cylinder. Such a synchronous cylinder is a double-acting hydraulic cylinder which operates with the same stroke force and the same stroke speed in the direction of movement of the two pistons. The advantage of the presence of these piston rods is that they guide the piston 4 and thus allow the piston to be constructed more simply. Furthermore, a displacement measuring system can be connected to the piston rod, by means of which the piston 4 can be moved steplessly, as a result of which the printing technology liquid 1 can be finely dosed steplessly. The metering device 6 shown in fig. 4 corresponds in construction exactly to the metering device 6 shown in fig. 3, except for the presence of the piston rod, so that for greater clarity not all structural elements are shown in fig. 4.

Fig. 5 shows a second embodiment, which differs from the first embodiment (fig. 3) only in the construction of the pump 2 and the multiplex valve 5. In the second embodiment the piston 4 is loaded by a spring 27. When the multi-way valve 5 is in its valve position shown in fig. 5, the spring 27 moves the piston 4 to the left in fig. 5, whereby the piston 4 displaces the printing technology liquid 1 out of the cylinder of the pump 2 and presses it via the multi-way valve 5 to the outlet 24. If the multi-way valve 5 is in its other valve position, the piston 4 is moved to the right by the hydraulic pressure of the printing fluid 1 and counter to the restoring action of the spring 27 until the piston 4 comes to a stop at a stop 28 which is adjustable to limit the piston movement and thus the metering quantity. In this case, a delivery pump 11 (fig. 1) pumps the printing technology liquid 1 via a line system 14 and a multiplex valve 5 into the cylinder of a pump 2, the expansion chamber of which is enlarged and refilled with the printing technology liquid 1. These two pump beats, i.e., filling and emptying, are repeated as often as required by the desired dosing volume. The control device 3 (fig. 2) counts the number of strokes of the piston 4 for determining the dosing volume.

In the event of a possible system defect, the piston 4 executes at most one stroke, and the spring 27 then fixes the piston 4 in its end position on the left in fig. 5, so that in the second exemplary embodiment, the continued operation of the pump 2 and the resulting overdosing of printing technology liquid 1 are reliably avoided.

Reference numerals

1 printing technology liquid 15 machine control device

2 Pump 16 holding device

3 control device 17 slide

4 piston 18 orbit

5 multi-way valve 19 ink fountain roller

6 dosing device 20 control Signal

7 first ink fountain 21 control signal

8 second ink fountain 22 control signal

9 feeding device 23 arrow

10 reservoir 24 outlet

11 transfer pump 25 arrow

12 first press 26 sensor

13 second printer 27 spring

14 tubing 28 stop

Claims (17)

1. Method for metering a printing technology liquid (1) by means of a pump, characterized in that the pump (2) is driven by the printing technology liquid (1).

2. The method according to claim 1, characterized in that the printing technology liquid (1) is a printing ink or varnish.

3. The method according to claim 1 or 2, wherein the pump (2) is a piston pump.

4. A method as claimed in claim 3, characterized in that the metered volume of the printing technology liquid (1) is determined by counting, by means of the control device (3), the number of strokes of a piston (4) of the piston pump proportional to the metered volume.

5. Method according to claim 4, characterized in that the piston is acted upon with printing technology liquid by means of a multi-way valve (5), the multi-way valve (5) is controlled by a control device (3) by means of control signals (21) and the control signals (21) are counted by the control device (3).

6. Device (6) for metering a printing technology liquid (1), comprising a pump (2), characterized in that the pump (2) is driven by the printing technology liquid (1).

7. The device according to claim 6, characterized in that the printing technology liquid (1) is a printing ink or varnish.

8. The device according to claim 6 or 7, characterized in that the pump (2) is a piston pump.

9. The device according to claim 8, characterized in that the piston pump has a piston (4) and a control device (3) is present for counting the number of strokes of the piston (4) which is proportional to the metered volume of printing technology liquid (1).

10. The device according to claim 9, characterized in that the piston (4) is acted upon with printing technology liquid by means of a multi-way valve (5) and the control device (3) is configured for controlling the multi-way valve (5) by means of control signals (21) and for counting these control signals (21).

11. Printing machine having a dosing device (6) according to one of claims 6 to 10.

12. System comprising a first ink fountain (7), a second ink fountain (8), a common supply device (9) for supplying printing technology liquid (1) to the first ink fountain (7) and the second ink fountain (8), wherein the common supply device (9) is connected to the first ink fountain by means of a metering device (6) according to one of claims 6 to 10 and to the second ink fountain (8) by means of a further metering device (6) according to one of claims 6 to 10.

13. The system according to claim 12, wherein the common supply (9) comprises a reserve container (19) for storing the printing technical liquid (1) and a delivery pump (11) for pumping the printing technical liquid (1).

14. The system as claimed in claim 12 or 13, wherein the system comprises a first printing machine (12) in which the first ink fountain (7) is arranged, and a second printing machine (13) in which the second ink fountain (8) is arranged.

15. Method for driving a pump (2) by means of a driving fluid, characterized in that a printing technology liquid (1) is used as the driving fluid.

16. The method according to claim 15, wherein the pump (2) is a piston pump.

17. The method according to claim 15 or 16, characterized in that the printing technology liquid (1) is a printing ink or varnish.