DE456624C - Dampening device for lithographic printing presses - Google Patents

Description

Lithographic printing presses are known

with dampening table and dampening rollers. With such presses the problem arises that the stone is already dry at the edges as a result of evaporation while it in the middle part is still damp. The consequence of this is that the deductions to the The edges are easily stained with paint.

You have now thought of the moistening table

and the dampening rollers by other devices, e.g. B. by moistening felt belts or to be replaced by a series of valves cooperating with a water trough, through which the liquid gets to the stone.

However, these devices have the major disadvantage that they are used in the existing, All too radical changes are required for lithographic presses working with dampening table and dampening rollers do without avoiding the dry edges of the stone in an impeccable manner. The present invention now overcomes this disadvantage in such a way that they in addition to known dampening rollers provides additional dampening rollers for the stone edges, so that there is a guarantee that these edges will remain moist.

The device is expediently made in such a way that the dampening rollers pivot on Levers are arranged on which there are still special wheels, the lower edge of which protrudes further than that Damp rollers so that when the paint table hits these wheels, it lifts them, so that any contact between the additional dampening rollers and the paint table is avoided will.

One of the possible embodiments of the subject matter of the invention is shown in the drawing illustrated, namely represent:

Fig. Ι a planographic printing press in longitudinal section,

Fig. 2 a part of the press in plan and

Fig. 3 the planographic printing press in a vertical cross-section.

The bed α of the planographic printing press is moved back and forth; it carries the lithographic stone b into which the images to be printed are etched. The color table c carries the color with which the stone is colored.

Above the press there is now an axis e which runs transversely to it and which is supported in supports s . A lever d is rotatably mounted on the axis e , so that it hangs down like a pendulum between two adjusting rings i, j serving as stops. One of these adjusting rings / carries a water container h, which has an adjustable tip p and an outlet pipe t . The lever d carries a pin at the free end on which a roll-shaped moistening pad g, which is constantly through the

4566M,.

Tube ί is fed, is rotatably arranged. This moistening roller g rolls along the edge of the stone (Fig. 3) and constantly moisturizes it, so that the edges of the stone are not colored and the sheets to be printed are not soiled.

Since, however, the color table e comes to lie in the same plane as the lithographic stone b , it is necessary not to expose the table c to the action of the dampening roller g when the former is perpendicular in front of the rod e when moving back and forth in the direction of the arrow / ( Fig. 1) comes to rest. For this purpose, a very thin wheel k is arranged at the end of the pendulum lever d , the edges of which are bevelled so that the wheel k only touches the plate of the color table c in one line. The wheel k is mounted on a pin which is lower than the axis of the dampening roller g. The diameter of the little wheel k is expediently so large that, when it rolls on the paint table c , the dampening roller g is lifted from its surface.

The position of the pendulum d on the rod e is such that the wheel k comes to rest in the space I (Fig. 2) between the stone and the edge of the bed , while the dampening roller g rests on the edge d of the stone b lays.

If the press is working, the stone edge is moistened with the backward movement of the bed α as long as the space / between the stone edge and the bed is available, ie up to the stone end (Fig. 1).

With continued movement of the bed a in the direction of arrow f (Fig. 1), however, the paint table lifts the wheel k and thereby pivots the lever d; the wheel k now rolls on the color table c, namely in the position k shown with dashed lines and thus removes the color table c from the action of the dampening roller g, which is in position g '.

When the lever d is rotated through the angle α, the outflow of water from the container h can be prevented, for example, by a rotatable closure which is inevitably connected to the lever d and which automatically blocks the mouth of the outflow pipe.

Claims (3)

Patent claims: 1. Feuchtvqrrichtung for lithographic printing presses, characterized in that in addition to the usual dampening rollers, additional dampening rollers (g) are provided for the stone edges, which are automatically lifted from their working position when the color table (c) approaches. 2. Damping device according to claim 1, characterized in that on a lever (d) which is rotatably mounted on a rod (e) mounted transversely to the press above the lithographic stone and which carries the dampening roller (g) , a wheel (k) is arranged that is lower than the dampening roller (g), so that when the wheel (k) is lifted through the paint table (c) the dampening roller (g) - is kept out of contact with it. 3. Apparatus according to claim 2, characterized in that the wheel (k) is beveled at the edges. For this purpose ι sheet of drawings.