EP0557607A1 - Cleaning device for a cylinder of a rotary printing machine - Google Patents

Abstract

A device for applying cleaning liquid to a cylinder of a rotary printing machine having a controlled supply to outlet apertures of a distributing device, from which the cleaning liquid can be sprayed onto the cylinder in a particular temporal and spatial quantity distribution. Provided upstream and downstream of the region of the spraying jet are guide elements (6.1, 6.2) which bound the region towards the outside for damming the jet. The guide elements (6.1, 6.2) are attached to the distributing device (2) and span the difference between the distributing device (2) and the outer surface of the cylinder (1), forming narrow gaps (7.1, 7.2) between the guide elements and the outer surface of the cylinder. At least in the downstream gap (7.2) there is a flow labyrinth (8). <IMAGE>

Description

The invention relates to a cleaning device for a cylinder of a rotary printing press according to the preamble of claim 1.

The cleaning device is used in particular for cleaning a printing cylinder or a blanket cylinder of a printing press.

The cleaning device contains a distributor for automatically controlled spraying of cleaning liquid onto the cylinder, and guide elements, which are located next to the Extend the spray jet from the distributor to the cylinder and form a narrow gap between itself and the cylinder behind and in front of the spray jet, the rear gap being the first gap in the direction of rotation of the cylinder and the front gap being the second gap in the direction of rotation of the cylinder.

A cleaning device of this type is known from US Pat. No. 3,084,626. In the known device, the guide elements are spaced apart from the spray jet, so that they do not limit the spray jet, but only prevent liquid parts from inadvertently spraying onto adjacent machine parts.

Furthermore, US Pat. No. 3,900,003 shows a liquid application device for applying developer liquid to a cylinder in a multicolor electrophotography copying machine. AT-PS 282 662 shows a wiping cylinder which has a cylinder section which is immersed in a vessel with cleaning fluid and a section which lies against a cylinder of a printing press to be cleaned. Cleaning liquid for rinsing the wiping cylinder is sprayed onto the area of the wiping cylinder emerging from the liquid between two spaced-apart doctor blades. DE-PS 12 40 885 shows a suction box opposite a pressure cylinder. The suction box can be pivoted through an axis parallel to the cylinder and forms a gap with the cylinder. The suction box is provided with brushes at the gap inlet and at the gap outlet and has suction holes in the area between these brushes for suctioning dust from the surface of a paper to be printed, which is around the cylinder surface running. DE utility model 1 996 060 shows a device for spraying liquid into the gap between two rollers in the printing unit of an offset printing press in order to moisten its printing plates. The dispensing of the liquid is controlled in a pulse-like manner by a control device of the printing press as a function of the printing speed and as a function of a selectable factor and with a selectable spray duration. Furthermore, from DE-OS 34 46 757 A1 a coating device for coating paper webs is known which forms a paint application storage space opposite the paper web guided by a cylinder, which is provided with a labyrinth overflow seal against the direction of rotation of the paper web and the cylinder.

Cleaning devices of this type are used to loosen the dirt that accumulates during the printing process and adheres to the cylinder surface. In conventional rotary printing presses, a squeegee or a cloth soaking up the dirt with solvent is used to remove the dirt softened by the cleaning liquid. In the case of web-fed rotary printing machines, the dirt is also removed directly from the web when the cylinder subjected to the cleaning process is in contact with the web unwind. Several principles are thus known for the transfer of the cleaning liquid to the cylinder surface. One principle is based on application by one Wiping process, for which different soaked materials can be used. Another principle is based on the application of the cleaning liquid by means of bristles or bristle rollers, by means of which the contaminated outer surface is mechanically cleaned at the same time. Another principle is based on spraying the cleaning liquid onto the outer surface of the cylinder, the cleaning liquid being conveyed by its own pressure or by the pressure of a gaseous carrier medium.

The principle of spraying is widespread because, in contrast to the touching application devices, the spraying device does not come into contact with the dirt and is also easy to switch. The duration and energy of the beam are easy to set. The disadvantage of spraying is that the surface to be cleaned moved under the jet is sometimes not wetted as well as is possible with wiping devices. In addition, there are rebound effects and decompression effects of the washing liquid, as a result of which parts of the liquid quantity provided for cleaning the cylinder jacket surface are lost. The incorrect quantities of liquid, which do not moisten the cylinder, reach undesired places on the printing press and sometimes cause undesirable effects such as corrosion or printing material malfunctions. Unwetted wetting liquid collects on the side of moistened areas, which forms drops that can get onto the substrate.

The waste of cleaning liquid is also unavoidable for kinematic reasons, because the movement and the forces of the liquid jet with respect to the rotating cylinder do not result in a perfect transition of the liquid into a wetting film. Drops hitting the surface of the cylinder bounce off at various angles.

The object of the invention is to keep the loss of cleaning liquid as low as possible and to make the transfer of the liquid more effective when blasting onto the cylinder surface.

This object is achieved by the features specified in claim 1.

The decompression of the cleaning liquid escaping under pressure and the disordered distribution are contained by at least parts of the transmission path being closed by a chamber-like structure. The shielding of the transmission space between the jet device and the outer surface of the cylinder influences the pressure profile, which extends from the point of the still existing internal pressure in the line at the outflow opening to the point near the rotating outer surface. By specifying the flow cross sections of the chamber reaching up to the cylinder, the flow pressure is influenced. The pressure equalization with the ambient pressure at the inevitable opening as a gap between the shield, The surrounding area and the moving surface of the cylinder is designed with a labyrinth seal, through which the flow energy is reduced to the rest. With a small pressure difference from the shielded room to the surroundings, little liquid escapes into the surroundings, but mainly passes over to the cylinder surface. Small dimensions of the insulation device are desirable for reasons of space. This means that only small dimensions are available for the flow path to be provided with the highest possible pressure loss. The flow cross section is therefore kept small and as many corners as possible are provided.

The pressure of the cleaning fluid under pressure is released in the case of a distribution device which is spaced parallel and extends to the cylinder jacket surface by means of a first rear gap and a second front gap in the direction of rotation of the cylinder. A larger amount flows out in the direction of rotation of the cylinder, because there is a suction effect in this direction, especially when the cylinder has a greater peripheral speed. In order to counter the increased spray discharge at the front gap in the direction of rotation, the labyrinth in question is laid out longer on this side. If the labyrinths have the same mechanical design, the front labyrinth element in the direction of rotation is longer than the rear labyrinth element.

Wetting cleaning liquid that collects on the surfaces of the labyrinth can, so that it does not run off at the end of the application phase or dripping, can be removed by deliberate draining. For this purpose, according to a special embodiment, the distribution device and the guide elements are tilted and the amount flowing off is fed to a sump.

In the simplest case, the guide elements consist of a covering bridging the space between the distributor device and the cylinder, with a front and rear chamber wall seen in the direction of rotation. A screen mesh can be arranged on the free, non-contacting edges of the cladding opposite the cylinder jacket, which separates the mist droplets and is a "flow baffle".

A labyrinth design with axially running grooves, grooves next to projections or edges is more complex, but better. There is a changing pressure profile from the lead to the groove or from mountain to valley. Less liquid remains on the labyrinth walls than in the mesh. Additional insulation is achieved by double-walled construction of the labyrinth elements with openings or holes in the interior of the double wall. This creates a further escape route for the liquid, the mist and the liquid pressure.

In addition to the tiltability for the distribution device with its attached labyrinth elements for the controlled drainage of residual liquid, provision can be made to move the distribution devices between the working position and a rest position. The labyrinth elements or the entire application device can be designed so that they can swivel in the rest position in a small space.

Fig. 1

eine Reinigungsvorrichtung mit einem Verteiler in einem Kammergehäuse;

Fig. 2

einen Verteiler mit angesetzten Labyrinthelementen

Fig. 3

einen Verteiler mit doppelwandigen Labyrinthelementen

Fig. 4

einen Verteiler mit verstellbarem Abstand.

The invention is described below with reference to the drawings based on preferred embodiments. Show it

Fig. 1

a cleaning device with a distributor in a chamber housing;

Fig. 2

a distributor with attached labyrinth elements

Fig. 3

a distributor with double-walled labyrinth elements

Fig. 4

a distributor with adjustable distance.

In relation to a cylinder 1 of a printing unit of a printing press, which is a blanket cylinder here, a distributor 2 extending parallel to the axis is arranged. The distributor 2 has outlet openings 3, through which the entire width of the cylinder 1 can be acted upon by cleaning liquid. The outlet openings 3 exist as a number of holes or as an elongated slot. In order to prevent cleaning fluid flowing in after a controlled spray or jet interval has ended, the outlet openings 3 can be provided with locking needles or locking covers which can be controlled mechanically or electronically.

The cylinder 1 rotates in the direction of rotation Z, in which the cleaning liquid applied to its outer surface is also transported. In the direction Z runs a flow caused by the moving lateral surface of the cylinder 1, which reaches a certain thickness depending on the viscosity of the surrounding medium, here ambient air with spray mist and solvent vapor. Cleaning fluid emerging from the outlet openings 3, which drops from the intrinsic pressure in the distributor 2 to the value of the ambient pressure and thereby bursts or swirls, is entrained in the direction of rotation Z with the moving lateral surface of the cylinder 1.

In Fig. 1 the distributor 2 is designed as a tube. This tube 2 is received in a U-shaped chamber housing 5. The chamber housing 5 is fastened to the side walls of the printing press by an adjustable holder 4. The opening of the chamber housing 5 points radially to the cylinder 1 or is inclined such that the direction of flow of the emerging cleaning liquid is partly tangential in the direction of rotation Z. On the outside between the outer surface of the cylinder 1 and a rear rear wall 6.1 of the chamber housing 5 there is a certain dynamic pressure which escapes in the direction of rotation via the distributor 2 and carries away the spray mist escaping through the rear gap 7.1 between the rear wall 6.1 and the cylinder jacket. The gap 7.1 between the rear wall 6.1 and the cylinder 1 is narrow. When the chamber housing 5 is positioned obliquely in the direction of rotation Z, it is the covering one Front wall 6.2 longer due to the geometric condition. The front wall 6.2 of the chamber housing 5, which does not come close to the outer surface, prevents the droplets of the cleaning liquid from escaping freely in the direction of rotation Z at the front gap 7.2. The amount of cleaning liquid sprayed from the outlet openings 3 mainly takes the path through the front flow gap 7.2, apart from the amount of mist which is deposited in the chamber housing 5. To reduce the amount of mist at the front flow gap 7.2, it is possible to attach a mesh 8 to form a partially open, lossy outlet cross section at the front flow gap 7.2. The fog or the drops are forced to escape through the many staggered free cross sections.

The function of the mesh 8 together with the front wall 6.2 of the chamber housing 5 is replaced in the embodiment of FIG. 2 by a front labyrinth element 9.2. The front labyrinth element 9.2, viewed in the direction of rotation Z, closes tightly at the distributor 2 and in turn forms a flow labyrinth for the front flow gap 7.2. Seen tangentially, it is formed to be wavy or angular, so that narrow and wide gap cross sections are alternately formed on axially extending projections 10 and grooves 11. The cleaning liquid emerging from the distributor 2 wets the outer surface of the cylinder 1, it also partially wets the front labyrinth element 9.2, and the flowing part passes through the flow labyrinth with an alternating pressure profile, with the alternating narrow or wide labyrinth cross sections alternating between relatively lower and higher pressures.

Seen against the direction of rotation Z, a rear labyrinth element 9.1 is also flanged onto the distributor 2. The rear labyrinth element 9.1 performs the same function as the front labyrinth element 9.2, with the difference that the subset of the cleaning fluid escaping from the distributor 2 that is escaping to the rear is smaller. As a result, the flow insulation to be performed is to be formed in the form of a shorter rear labyrinth element 9.1.

In the double-walled embodiment according to FIG. 3, the existing, pressure-reducing profile of the labyrinth elements 9.1; 9.2 encapsulating walls 12.1; 12.2 put on. Breakthroughs 13 allow droplets to penetrate into the buffer spaces 18 thus formed. A further flow path through the breakthroughs 13 is consequently added to the droplets flowing away through the labyrinth along the flow gaps 7.1 and 7.2. Droplets escaping through these openings 13, which cannot be transported to the lateral surface of the cylinder 2, are discharged from the inside via outlet connections 14. The outlet connection 14 can be connected to a sump (not shown) via a common drain line.

If the encapsulating walls 12.1; 12.2 are also provided with breakthroughs, the lossy flow path runs through the breakthroughs 13 into the interior and further out again, with emerging portions of cleaning fluid on the outer wall of the encapsulating Walls 12.1; 12.2 are to be collected and derived. The experience values determine the distance between the openings 13 and the distributor 2 and the diameter with which they are to be installed.

The advantage of a double-walled construction is that blocking or additional media can be introduced into the capsules with forwarding through the openings. Vacuum can also be applied to the capsule, so that excess mist can be extracted. This complex measure is advantageous if the formation of fog mainly occurs only in short phases.

The with the labyrinth elements 9.1; 9.2 created shielding the beam area of the distributor 2 leads to a channel 17 in the lateral surface of the cylinder 1 during passage under the labyrinth elements 9.1; 9.2 absorbs more cleaning liquid. The increased entry of cleaning fluid into the channel 17 can be prevented if an order bar 15 can be lifted by a correspondingly synchronized movement of a control cam 16, which can be formed by a cam or a cam shoulder. With the lifting of the order bar 15, the flow labyrinth or its flow gap 7.1 and 7.2 is expanded on one side. This is done by unilaterally increasing the distance between the rear labyrinth element 9.1 or the front labyrinth element 9.2 relative to the cylinder 1, or by increasing the distance between the two labyrinth elements 9.1 and 9.2 from the cylinder such that the pressure responsible for the penetration of cleaning fluid into the channel 17 disappears. If the application bar 15 swings suddenly, there is also the favorable effect that the liquid jet rotating during swiveling, if it is moved against the direction of rotation Z, the amount of cleaning liquid to be assigned to the channel area is reduced. With this measure, therefore, the channel 17 receives less cleaning liquid than the extended areas of the outer surface of the cylinder 1. The movement of the control cam 16 is controlled by a control device of the printing press.

1 to 4, identical or functionally corresponding parts are provided with the same reference numerals.

The spray jet 20 of the distributor 2 is preferably controlled automatically by the printing press. The time, the amount of liquid, the spray direction and / or the area of impact of the spray jet 20 on the cylinder 1 can be controlled. The device enables the cleaning liquid to be sprayed onto the cylinder in a specific time distribution and in a specific local quantity distribution or to be sprayed in the form of a sharp jet.

Claims (10)

Cleaning device for a cylinder of a rotary printing press, in particular for a printing cylinder or a blanket cylinder, with a distributor (2) for the automatically controlled spraying of cleaning liquid onto the cylinder (1), with guide elements (6.1, 6.2), which are located next to the spray jet (20) extend from the distributor (2) to the cylinder (1) and between itself and the cylinder (1) form a narrow gap (7.1, 7.2) behind and in front of the spray jet (20), which acts as a flow restrictor, the rear gap (7.1) being the first gap in the direction of rotation of the cylinder (1) and the front gap (7.2) in Direction of rotation of the cylinder (1) is the second gap,
characterized in that
the guide elements (6.1, 6.2) in front of and behind the spray jet (20) are arranged directly on the spray jet and limit it essentially without air space and lead in the direction from the distributor (2) to the cylinder (1). Cleaning device according to claim 1,
characterized in that
At least at the front gap (7.2) there is a flow labyrinth (8; 9.1, 9.2) for separating mist of cleaning liquid. Cleaning device according to claim 1 or 2,
characterized in that
the guide elements (6.1, 6.2) form a housing (5) and that the distributor (2) is accommodated in the housing (5). Cleaning device according to one of claims 1 to 3,
characterized in that
the guide elements (6.1, 6.2) extend approximately parallel to the direction of the spray jet (20). Cleaning device according to one of claims 1 to 4,
characterized in that
A flow labyrinth (7.2, 7.1) is provided at the front gap (7.2) and at the rear gap (7.1) for separating coating liquid mist. Cleaning device according to one of claims 1 to 5,
characterized in that
the labyrinth (9.2) at the front gap (7.2) is longer than the labyrinth (9.1) at the rear gap (7.1). Cleaning device according to one of claims 1 to 6,
characterized in that
the walls of the flow labyrinth (7.1, 7.2) are provided with drainage openings (13) for draining cleaning liquid and separated cleaning liquid mist from the gap (7.1, 7.2) into a drainage chamber (18) which is located downstream of the drainage openings (13). Cleaning device according to one of claims 1 to 7,
characterized in that
the labyrinth elements (9.1, 9.2) and the distributor (2) can be set to different distances from the cylinder (1). Cleaning device according to one of claims 1 to 8,
characterized in that
the flow labyrinth is formed by a mesh (8) or an arrangement (9.1, 9.2) of alternating wave crests (10) and wave troughs (11), which extend parallel to the cylinder (1). Cleaning device according to one of claims 1 to 9,
characterized in that
the distributor (2) together with the guide elements (6.1, 6.2) and the labyrinth elements (9.1, 9.2) relative to the cylinder (1) are automatically lifted each time a channel (17) formed in the circumference of the cylinder (1) passes and after passing by this channel (17) is automatically lowered back into the original position.

Images