Device for Supplying Ink to a Printing Press

Abstract

A device for supplying ink to a printing press, includes a piston pump and a hydraulic or pneumatic cylinder driving mechanism which drives the piston rod of the piston pump and the cylinder driving mechanism includes several cylinder chambers, which are separated from one another and each of which contains a driving piston, which can be acted upon with pressure.

Description

The present invention relates to a device for supplying ink to a printing press in accordance with the introductory portion of claim 1.

Printing machines, for example, for offset printing, are usually supplied with ink by equipment, which comprises an ink pump and an appropriate driving mechanism for the public. Usually, piston pumps, the piston rod of which is driven by a hydraulic or pneumatic cylinder, are used in this connection.

As the operating speed and efficiency of modern printing presses increase, their ink consumption and, with that, the volume pumped by the ink pump also increase. Furthermore, in those cases, in which the ink barrels are far removed from the printing press, it may be necessary to build up a high pumping pressure. For this reason, there is a need for cylinder driving mechanisms, which are in a position to employ a very high driving force.

One possibility for achieving this objective consists of scaling the driving cylinder correspondingly, that is, of increasing the capacity of its cylinder chambers. However, this entails various disadvantages. The external dimensions of the driving cylinder are increased disproportionately. Furthermore, problems arise with respect to supplying fluid under pressure, especially in the case of pneumatic cylinders, since a correspondingly high fresh air pressure must be built up and the air consumption increases. Moreover, the costs of constructing suitable single stage cylinders, which can be used with the usual piston pumps for pumping ink, increase.

It is therefore an object of the present invention to provide a device for supplying ink to printing presses of the type named above, the driving force of which device can be increased for increasing the volume pumped and the pumping pressure of which can be increased while avoiding the structural disadvantages named above.

Pursuant to the invention, this objective is accomplished by a device for supplying printing ink with the distinguishing features of claim 1.

The cylinder driving mechanism of the inventive device for supplying printing ink comprises several cylinder chambers, which are separated from one another and each of which contains a driving piston, which can be acted upon with hydraulic or pneumatic pressure. Due to this construction, a higher driving force can be attained without having to build up an excessive pre-pressure in the pressure fluid and without an excessive consumption of fluid. Moreover, the external dimensions of such a cylinder driving mechanism are kept within justifiable limits.

For a preferred embodiment, the cylinder driving mechanism comprises at least one tandem cylinder.

In a further preferred embodiment, the cylinder driving mechanism comprises at least two cylinder chambers, which are disposed parallel to and next to one another and which each contain a driving piston.

In the following, a preferred example of the invention is described in greater detail by means of the attached drawing, in which

FIG. 1 shows a perspective view of an embodiment of the inventive device supplying ink to a printing press,

FIG. 2 shows a perpendicular longitudinal section through the cylinder driving mechanism of the device for supplying ink along the plane A-A in FIG. 1 and

FIG. 3 shows a further longitudinal section in a plane B-B, which is perpendicular to the plane A-A.

The device 10 of FIG. 1 is provided for pumping ink from an ink barrel to an offset printing press. For the sake of clarity, the barrel as well as a printing press has been omitted in the Figure. As essential elements, the device 10 for supplying ink comprises a piston pump 12 in a lower section of the device 10 and a pneumatic cylinder driving mechanism 14, which is mounted thereabove. The piston pump 12 and the cylinder driving mechanism 14 are disposed above one another in the form of a vertical column. As will be explained in even greater detail in the following, the cylinder driving mechanism 14 drives a vertical piston rod, which extends in the interior of the piston pump 12, linearly in an up and down motion. For this purpose, the piston rod extends upward into the cylinder driving mechanism 14 and is provided with a driving piston, which can be acted upon with compressed air. Details of the construction of the driving mechanism 14 will be explained in even greater detail in the following.

The piston pump 12 itself is of a known construction and comprises a cylindrical tubing 18, in which a pumping piston is driven up and down by a piston rod. The lower end of the tubing 18 is connected over a connector 20, which is provided with seals and seals an inlet pipe 22, at the free and 24 of which a hose or a pipeline for connection with the ink barrel can be connected. The inlet pipe 22 is connected by a connector 20 at right angles with the tubing 18. A foot plate 26 for mounting on the floor, on a machine frame or the like, adjoins the lower end of the connector 20.

The piston pump 12 furthermore comprises two connecting lines 28, 30, which start out laterally from different places of the periphery of the tubing 18 and are to be connected to hoses supplying the printing press, which is not shown. Accordingly, the piston pump 12 pumps the ink, aspirated through the inlet pipe 22 over the connector 20 and the tubing 18, through the connecting lines 28, 30 to the printing press.

The pneumatic cylinder driving mechanism 14 comprises a vertical tandem cylinder 32, the interior of which has two separate cylinder chambers, in each of which a driving piston can be moved up and down. Both driving pistons are mounted at the piston rod of the piston pump 12, the piston rod extending upward into the tandem cylinder 32. A lower, square terminating plate 34 and a corresponding upper terminating plate 38 close off the tandem cylinder 32 at the upper and lower ends, while an intermediate plate 36, halfway between the two terminating plates 34, 38, separates the two cylinder chambers from one another in the interior of the tandem cylinder 32. An upper casing section 40 and a lower casing section 42 are disposed in each case between the upper terminating plate and the intermediate plate and between the lower terminating plate 34 and the intermediate plate 36 and, in each form the outer limiting wall of a cylinder chamber. Four outer struts 44, the ends of which are bolted to the corners of the plates 34 and 38 and which extend through the intermediate plate 36, give the tandem cylinder 32 adequate mechanical stability.

A control unit 46 in a switchbox, which is mounted outside on the side of the cylinder driving mechanism 14, acts on the driving piston within the tandem cylinder 32. The control unit 46 distributes compressed air, which is supplied by a compressed air line 48, over compressed air lines 50 to four compressed air connections 52, 54, 56, 58, which are mounted in pairs at the tandem cylinder 32. Each pair of compressed air connections 52, 54 as well as 56, 58 serves to act with compressed air upon one of the two cylinder chambers of the tandem cylinder 32 in one of two directions of motion of the driving piston contained therein and, at the same time, to discharge the air, displaced by the driving piston during its movement, through rapid air bleeders 60 at the compressed air connections 52, 54, 56, 58, as explained further below. The upper pair of compressed air connections 52, 54 is mounted one above the other at the upper terminating plate 38 and at the intermediate plate 36 in FIG. 1, front right at the cylinder driving mechanism 14, while the pair of lower compressed air connections 56, 58 is mounted front left at the intermediate plate 36 and the lower terminating plate 34.

The sections in FIGS. 2 and 3 explain the mode of functioning of the tandem cylinder 32. The intermediate plate 36 divides the interior of the tandem cylinder 32 into two cylinder chambers of equal size, namely a first cylinder chamber 62 between the lower terminating plate 34 and the intermediate plate 36 and a second cylinder chamber 64, which is disposed above in the operating position in FIG. 1 between the middle plate 36 and the upper terminating plate 38. In each of the two cylinder chambers 62, 64, a driving piston 66, 68 is disposed, which closes off the cylinder chamber 62, 64 air-tight at its periphery with the outer section of the casing 40, 42. If therefore the piston 66, 68 is acted upon with the pressure on one of its sides, it moves in a sliding motion to the opposite side.

An upper section of the piston rod 70 extends from the piston pump 12, which is not shown, through the lower terminating plate 34 and the intermediate plate 36 through the driving piston 66 of the first cylinder chamber 62 into the driving piston 68 of the second cylinder chamber 64. The piston rod 70 is guided and slides in the lower terminating plate 34 and in the intermediate plate 36. However, it is seated firmly in the two driving piston 66, 68 and is connected with these in one piece, so that the piston rod 70 is always carried along during a movement of the driving piston 66, 68. Accordingly, by the action of pressure on the driving piston 66, 68 from above, the piston rod 70 is pressed into the piston pump 12 and, by the action in the opposite direction, it is pulled out once again.

Compressed air acts on the respective cylinder chamber 62, 64 over compressed air channels, which are passed into the respective terminating plates 34, 38 as well as into the intermediate plate 36. In particular, a first, middle compressed air channel 72, which extends in the radial direction perpendicularly to the piston rod 70 into the intermediate plate 36 and is angled therein to the second cylinder chamber 64, and an also angled upper compressed air channel 72 in the terminating plate 38 serves to act upon the second cylinder chamber 64 with compressed air over the first compressed air connection 52 from the opposite side of the driving piston 68.

As is evident in FIG. 3, a second middle compressed air channel 76 extends similarly in the intermediate plate 36 to the first cylinder chamber 62 in order to act upon the lower driving piston 66 with compressed air from above, which is supplied over the compressed air connection 56 in FIG. 1, while a lower compressed air channel 78 is passed into the lower connecting plate 34 in the radial direction and discharges into the opening 80, through which the piston rod 70 is passed through the lower connecting plate 34. Due to the axial opening 80, there is a connection between the lower compressed air channel 78 and the first cylinder chamber 62, so that the latter is acted upon with pressure over the lower compressed air connection 58 or, alternatively, if the lower driving mechanism piston 66 is moving in the opposite direction, can be vented over the rapid air bleeder 60.

During the operation of the driving cylinder, initially the upper compressed air connections 52, 56 of the respective cylinder chambers 62, 64 are acted upon with pressure, so that the pressure is transferred to the respective upper action surfaces of the driving piston 66, 68 and presses these, together with the piston rod 70, in the direction of the piston pump 12. Alternatively, the air, displaced by the driving piston 66, 68, can escape rapidly over the compressed air channels 72, 78 and the rapid air bleeder 60 of the compressed air connections 54, 58. Moreover, the driving cylinders 66, 68 move out of the end position, shown in FIGS. 2 and 3, to their lower stop at the intermediate plate 36 and the lower terminating plate 34 respectively. Subsequently, the piston rod 70 is moved in the opposite direction, in that the driving pistons 66, 68 are acted upon from their underside with pressure by way of the compressed air channels 72, 78, so that they are pressed upward, while the displaced air on the opposite side of the driving piston 66, 68 escapes through the compressed air channels 74, 76. In this way, by alternately acting upon the appropriate pressure connections 52, 54, 56, 58 with compressed air, an up and down movement of the driving pistons 66, 68 and, with that, of the piston rod 70 can be obtained.

Compared to a one-stage pneumatic cylinder, the tandem cylinder 32, presented here, has the advantage that the driving force, transferred to the piston rod 70, can be increased without having to increase the pressure or consumption of the air supplied significantly. As can be seen particularly in FIG. 1, the external dimensions of the cylinder driving mechanism 14 as a whole are maintained within justifiable limits. By increasing the driving force with relatively simple means, the pumping pressure and the volume pumped by the piston pump 12 can be increased in a simple manner.

The present invention is not restricted to hydraulic or pneumatic tandem cylinders in the strictest sense. Instead, other arrangements of separate cylinder chambers of the driving mechanism are also conceivable, such as a multistage driving mechanism with several consecutively connected chambers in structurally separate cylinders, the driving pistons of which are seated on a piston rod 70, extending through the cylinders, in much the same way as shown here in the Example. Moreover, the cylinder chambers of the driving mechanism 14 may be disposed in parallel and their driving pistons may act jointly on the piston rod 70.

Claims

1. A device for supplying ink to a printing press, comprising:

a piston pump having a piston rod, and

a cylinder driving mechanism which drives the piston rod of the piston pump, the cylinder driving mechanism including several cylinder chambers which are separated from one another and each of which includes a driving piston which can be acted upon with pressure.

2. A device for supplying ink of claim 1, wherein the cylinder driving mechanism comprises at least one tandem cylinder.

3. A device for supplying ink of claim 1, wherein the cylinder driving mechanism comprises at least two parallel cylinder chambers, which are disposed next to one another, each of which includes a driving piston.

4. A device for supplying ink of claim 1, wherein said cylinder driving mechanism is one of:

a pneumatic cylinder driving mechanism, and

a hydraulic cylinder driving mechanism.

5. A device for supplying ink of claim 2, wherein the cylinder driving mechanism comprises at least two parallel cylinder chambers, which are disposed next to one another, each of which includes a driving piston.

6. A device for supplying ink of claim 1, wherein the cylinder driving mechanism comprises at least two serial arranged cylinder chambers, which are disposed one above another, each of which includes a driving piston.