Patent Application
20070033764
The invention relates to a cleaning device for the surface of cylinders of a printing machine as well as a nozzle for installation in such a cleaning device. The cleaning device comprises a nozzle with a nozzle opening for a for a jet of cleaning fluid, a distribution line for cleaning fluids, into which the nozzle is inserted, as well as a cleaning element for lifting contaminants dissolved by the cleaning fluid off the surface of the cylinder. In addition to a nozzle opening, the nozzle comprises a base for insertion into the distribution line for cleaning fluids as well as a channel extending, on the one side, to an opening in the base and, on the other side, to the nozzle opening.
For guidance, processing, and for driving printed material sheets or printed material webs in printing machines, an intense contact is necessary between the printed material and the cylinders of the printing machine. Therefore, when paper is used as the printed material, for example, deposits of paper dust (fibers, coat, fillers etc.), ink, and perhaps powder dust develop on the cylinders. These deposits influence the cylinders in their functionality. For printing quality and operational safety as well it is necessary to clear the cylinders of printing machines of contaminants in regular intervals.
This generally occurs via automated cleaning devices, which apply cleaning fluids onto the surfaces of the cylinders to be cleaned and use brushes or cloth as cleaning elements in order to lift contaminants dissolved by the cleaning fluids off the surface of the cylinder. EP 1 106 355 A1 shows an example of such a cleaning device.
When printing paper webs, the regularly required cleaning of the surface of the cylinders of a printing machine must be performed under operating conditions in order to avoid considerable production down times, i.e. during the cleaning process the paper web continues to travel through the printing machine causing discards to develop. In order to keep the time for cleaning the surface of the cylinders as short as possible, usually the cleaning is performed at production speed, producing from 5 to 25 discards per second. Considering costs, it is therefore desirable to apply the cleaning fluids in the most efficient way possible and, in particular, also to ensure the spatial and temporal distribution of the applied cleaning fluid to be as even as possible.
The known cleaning devices are generally provided with a spray pipe, which serves as a distribution line and has a multitude of nozzle openings evenly distributed over its length. Using this spray pipe, the cleaning fluids are then applied on the cleaning element of the cleaning device, e.g., a brush (EP 1 106 355 A1).
However, a spray pipe with nozzle openings is not optimal for the desired spatially and temporally even distribution of the cleaning fluids applied. Generally, a more or less directed jet exits the nozzle openings so that the local distribution of the cleaning fluids varies in the axial direction by the nozzle openings. Therefore, for example brush rolls, onto which the cleaning fluids are sprayed, are provided with an axially oscillating motion and an appropriate adjustment drive for an even axial distribution of the cleaning fluids.
The above-described problem of the required even spatial and temporal distribution is further enhanced in heat-set printing machines having a dryer, through which the printed material is guided after printing. Here, when cleaning the surface of the cylinders under operational conditions, the printed material carries cleaning fluids into the dryer during the cleaning process. The conventionally used cleaning fluids have a relatively high content of volatile hydrocarbons, which enter the dryer and, through the heat developed, under unfavorable conditions, can reach a flammable concentration when evaporating. Here, it is also essential that excess amounts of cleaning fluid are avoided during the cleaning process. However, an optimal cleaning effect is to be achieved with a cleaning time as short as possible. Thus it is of the utmost importance to apply the cleaning fluids with an efficiency that is as high as possible, which particularly means to design the spatial and temporal distribution of the cleaning fluids applied as evenly as possible.
An effective means to achieve a spatially even distribution of cleaning fluids is the use of nozzles having a deflector surface arranged downstream from the nozzle opening for deflecting and fanning the jet exiting the nozzle opening. This principle is known from other applications, for example the application of pesticides in agriculture. However, until now, it has hardly ever been used in the present field of cleaning devices for printing machines because appropriate nozzles require an installation space usually not available in such cleaning devices. Further, nozzles of this type are still faced with the problem, that the nozzle opening must not be selected too small, as not to become clogged by residue. However, a nozzle opening being too large prevents the desired temporally even distribution of the cleaning fluid applied, as described above, because too much cleaning fluid per time unit can flow through.
The present invention is therefore based on the object to optimize a cleaning device for the surface of cylinders of a printing machine of the type mentioned at the outset and a nozzle therefore, such that a better spatially and temporally, even distribution of the applied cleaning fluid is possible.
This object is attained in a cleaning device having the features of claim 1. Advantageous embodiments and further developments of the cleaning device according to the invention are described in claims 2 through 8. A nozzle attaining the above-mentioned object is defined in claim 9. Preferred further developments of the nozzle are found in claims 10 through 16.
According to the present invention, the nozzle with its nozzle opening is embodied as a separate component, with its deflector surface arranged in front of the nozzle opening for deflecting and fanning the jet exiting the nozzle opening, with its base to be inserted into a distribution line for cleaning fluids, and its channel, which, on the one side, extends to an opening in the base and, on the other side, to a nozzle opening, being made from a soft-elastic material, in particular plastic or rubber. This results in several different advantages.
Due to the soft-elastic embodiment of the nozzle, the nozzle opening can be selected very small in order to allow dosing the jet of cleaning fluid more precisely and to design the temporal distribution of the applied cleaning fluid more evenly. Due to the fact that the channel with the nozzle openings is surrounded by an elastic material, which particularly behaves in a flexible manner during an operation with pressure pulses by expanding and contracting again to a small extent, the danger of clogging the nozzle opening with residue from the cleaning fluids is only very slight.
Further, the soft-elastic embodiment of the nozzle allows an easy exchange, by mounting it to the distribution line using its elasticity, for example by pressing it into a corresponding opening. When the nozzle is embodied appropriately small, even a retrofitting of conventional spray pipes is possible. Such a mounting to the distribution line using the elastic features of the nozzle can be considerably supported, here, in that the base of the nozzle is provided with a bead for undercutting an opening in the distribution line. Once this bead is pressed through the opening in the distribution line, the nozzle is held in the opening even against high applied pressures.
Another advantage of the cleaning device and the nozzle according to the invention includes its cost-effective production, with production of the nozzle as a plastic part made as an injection molding being noted.
Thus, the invention provides a novel nozzle as well as a cleaning device having such a nozzle, which can be provided with a very small nozzle opening without increasing the risk of clogging with residues from the cleaning fluids. Even when the nozzle opening is clogged, it creates no serious problem because the nozzle according to the invention can be exchanged for a new one very easily, in seconds, and without the use of any tools.
The assembly of the nozzles according to the invention at the distribution line is facilitated when the nozzle has a base surface, supported on the exterior of the distribution line, which is adjusted thereto. Simultaneously, this results in an automatically correct alignment of the nozzle opening and the deflector surface; a crooked installation of the nozzle is prevented by the base surface. This imminent protection from a crooked installation is further improved when the nozzle is designed such that the nozzle opening is integrated in the base surface.
The unavoidable formation of mist during the spraying of cleaning fluids can be avoided in the nozzle according to the invention when a jet guidance area extends from the nozzle opening to the deflector surface so that the jet can flow along a bent surface. The jet then does not hit the deflector surface head-on but is constantly deflected and thus fanned out.
Beneficially, the deflector surface is advantageously provided with a drop-off edge at its side facing away from the nozzle opening, in order to ensure a defined formation and direction of motion of the fanned jet. By its very nature, the length L of the deflector surface, defined by the position of the drop-off edge, influences the level of fanning of the jet as well as its speed. Therefore the nozzle according to the invention can be optimized for its respective use by the optimal selection of the position of the tear-off edge. When the length L is selected small, the jet is slowed to a lesser extent, and simultaneously less fanned. When L is selected large, the jet is fanned wider, simultaneously lengthening the distanced over which the jet is slowed along the deflector surface, so that the speed of the jet is considerably reduced.
Finally, the nozzle according to the invention can be provided with a protective plate arranged recessed behind the drop-off edge.
In the following, an exemplary embodiment for a cleaning device and an exemplary embodiment for a nozzle according to the invention are described and explained in greater detail using the attached drawings. They show:
The nozzle 23 shown in
The nozzle is entirely comprised of a soft-elastic material, here injection-molded plastic, and is embodied such that the base surface 5, the deflector surface 6, and the protective plate 8 together form a widened nozzle body 9, by which the nozzle (its dimensions being in the range of 10 millimeters) can better held and, if necessary, be manually pressed into the opening of the distribution line 22 provided therefor.
The base surface 5 has two grooves 10 in order to increase its mobility and to ensure a better contact to the cylindrical surface of the distribution line 22.
In
Additionally, in
The representation according to
| Number | Date | Country | Kind |
|---|---|---|---|
| 05 017 362.4 | Aug 2005 | EP | regional |
