1. Field of the Invention
The present invention relates to a printing unit of a rotary printing press with a cleaning device, which cleaning device can be applied against, or positioned in relation to, a cylinder to be cleaned. The cleaning device can have a driven washer roller which washer roller is located in a housing in the vicinity of an opening in the housing, which opening faces the cylinder. The cleaning device can also have a cleaning agent feed device corresponding to the washing roller and a wiper strip. The cleaning device extends over the length of the cylindrical surface of the cylinder.
2. Background Information
German Patent No. 43 43 692 A1 shows a similar known device, in which a washing roller is used. The washing roller contains bristles and is located in a closed housing. On the housing there is a drain or discharge for the dirty washing fluid, which drain is connected to a container or tank by means of a connecting hose. The used washing fluid must then be disposed of.
On modern printing presses, the washing of a cylinder is performed with very little washing agent. The solvents which are used for cleaning are also extremely volatile. Consequently, the dirty washing fluid which runs off the washing roller collects in the lower portion of the housing, where a large part of the volatile solvents evaporate, so that only a small portion of the used washing fluid actually makes it to the discharge. Increasing quantities of used cleaning fluid dry up in the housing, to the point where in the known embodiment, the housing must be removed from the press for cleaning. To make matters worse, cleaning the housing is also an extremely difficult and time-consuming task. The closing devices used on the housing also tend to become stuck on account of the dirty washing fluid, and their removal entails additional time, effort and expense.