1. Field of the Invention
The invention relates to a sealing device for a dampener of an offset printing machine and more particularly to a sealing device for a dampener having a metering roller and an applicator roller. The applicator roller and the metering roller roll on one another in a way that, with an upper wedge shaped nip between these rollers, they form a channel or duct which can accommodate a supply of dampening medium. The sealing device seals the channel or duct at the end faces. Specifically, the sealing device has a sealing support bracket which is mountable on a lateral part of the dampening unit, and in which a sealing element is accommodated. The seal support bracket is pre-stressed against an end face of the rollers, the sealing element being sealingly supported radially on the metering roller, and sealingly engaging the end face of the applicator roller.
2. Description of the Related Art
From German Published Non-Prosecuted Application (DE-OS) 22 06 498, it has become known heretofore how to accumulate a supply of dampening medium in the duct between the metering roller and the dampening-medium applicator roller, which roll on one another. With respect to the sealing device of this heretofore known dampener, a sealing element, formed of resilient sealing material, is applied to both end faces of the metering roller and the dampening applicator roller. The sealing element is further formed of a blocking plate, in which the resilient sealing material is accommodated. The blocking plate is held in an upwardly open guidance device, and can be removed in this direction for purposes of exchange. It is secured in position by catch projections or detents, which snap into corresponding catch recesses formed in the blocking plate.
From European Published Non-Prosecuted Application (EP-A1) 0 047 350, there has become known, with respect to a dampening unit, a sealing device having the features mentioned in the introduction hereto. The sealing element, accommodated in the sealing support bracket, is both axially and radially pre-stressed by spring tension in the case of this heretofore known sealing device. The sealing is thus achieved in two directions, i.e. at the end face of the dampening applicator roller, in the one direction, and at the outer cylindrical surface of the metering roller, in the other direction. The configuration of this heretofore known sealing device is far from satisfactory, particularly with regard to the necessary exchange of the sealing element, which is constructed as a wearing part. In the case of this heretofore known sealing device, an upper marginal region of the sealing element is subjected to the action of a bracing or supporting spring, which is braced against an angle-shaped part overlapping the marginal region of the sealing element. This has an adverse effect upon accessibility, and makes the task of exchanging more difficult, which has been found to be time-consuming.