DD263264A1 - PAINTING WORK FOR OFFSET PRINTING MACHINES - Google Patents

Abstract

The invention relates to a coating unit for offset printing machines, which can be used for both direct and indirect inline coating and paint application outside the printing press for protective and gloss coating. The object of the invention to provide a coating unit for offset printing machines, in which for both the protective and the gloss coating of the same low-viscosity paint is used with a single coat, is achieved by a over the entire width of the roll extending pivoting blower either is arranged in the immediate vicinity of the surface of the paint applicator roller, the transfer roller, the plate or paint forme cylinder or the nip between paint applicator roller and plate or paint form cylinder. Furthermore, the blowing device can be designed as a blowing and suction device. Fig. 1

Description

For this 2 pages drawings

Field of application of the invention

The invention relates to a coating unit for offset printing machines, which can be used for both direct and indirect inline coating and paint job outside the printing press for protective and gloss coating.

Characteristic of the known state of the art

The lacquering of printed sheets within the printing press has greatly increased in recent years. The result is a distinction between glossy and protective lacquers: protective lacquering is usually carried out with low-viscosity lacquers and gloss lacquering either with highly viscous lacquers or by two coats with low-viscosity paint.

Should now be switched from the protective to the gloss coating, so there is the disadvantage that the sheet either a second time painted or the low-viscosity paint must be replaced by high-viscosity.

Object of the invention

The object of the invention is to provide a coating unit for offset printing machines, which contributes to reducing the non-productive times of the printing press, such as paint change and repeated sheet pass.

Explanation of the essence of the invention

The object of the invention is to provide a coating unit for offset printing machines, in which the same low-viscosity paint is used for both the protective and the gloss coating, in former painting.

According to the invention the object is achieved in that over the entire roll width extending pivotable blowing device is arranged either in the immediate vicinity of the surface of the paint application roller, the transfer roller, the plate or paint cylinder or the nip between paint application roller and plate or paint cylinder. Furthermore, the blowing device can be designed as a blowing and suction device.

Through the use of the blowing device or the combined blowing and suction device or a combined radiation dryer with blowing and suction for the first time the use of low-viscosity paints with their good dosing properties for the applications protective and gloss painting with unique Lackäuftrag has become possible.

embodiment

The invention will be explained in more detail below using an exemplary embodiment. In the accompanying drawings show:

Fig. 1: a working as a varnishing dampening unit (indirect inline paint) with blower Fig.2: a converted as l.ackierwerk printing unit (direct inline coating) with blower Fig. 3: coating unit according to Figure 2 with combined blow and suction

According to FIG. 1, the coating unit consists of three rollers, a scoop roller (1), a transfer roller (2) and a varnish applicator roller (3) which rolls on the plate or mold mounted on a plate cylinder (4). The scoop roller (1) immersed in a paint box filled with paint (5).

In the parked state is shown an inking roller (6) with connecting roller (7). In the immediate vicinity of the surface of the transfer roller (2), the plate cylinder (4) and below the paint application roller (3) blowing devices (8) over the entire roll width are arranged. Bias devices that are connected to the supply system of the machine and with

operated (dried and / or tempered) air-operated grazing, are well known and therefore not described in detail.

FIG. 2 and FIG. 3 depict a disassembled printing unit as a pure coating unit. The paint application is carried out directly, starting from the scoop roller (1) via the transfer roller (2), onto the coating cylinder (9), from which the paint is applied directly to the printed sheet passing between the impression cylinder (10) and the impression cylinder (9) Lackes is on the scoop roller (1) a metering roller (11) arranged when to be painted in reverse.

According to Figure 2, the blowing device (8) is arranged in this case in the immediate vicinity above and below the paint application roller (3).

The blowing device (8) below the paint application roller (3) according to Figure 1 and Figure 2 is pivotable, so that either the surface of the plate or paint form cylinder (4.9) or the paint application roller (3) are coated by dsm air flow

in the exemplary embodiment according to FIG. 3, the blowing device (8) is designed as a combined blowing and suction device (12). The arrangement essentially corresponds to that in FIG. 2.

The arrows indicate the direction of rotation of the individual rollers, wherein in each case a synchronism and counter-rotation, the so-called reverse operation, represented by the dashed arrows, is possible.

The advantage of the reverse operation is that a smoother paint job can be transmitted in synchronism.

The mode of action is the following:

By the rotational movement of the scoop roller (1) in the paint box (5) paint (water paint) is transferred via the transfer roller (2) or the Lackauftragwaize (3) on the plate cylinder (4) or Lackforrnzylinder (9) clamped form. From Lackforrnzylinder (9), the paint is voliflächig or recessed (depending on the form) transferred to the substrate.

If a protective coating of the printed product is then carried out with a low-viscosity paint and then a gloss coating is to be carried out, the low-viscosity paint is left in the paint box (5) and only the blowing nozzles (8) are put into operation. Depending on the requirement (viscosity), one or more blowing nozzles (S) can be operated. Due to the air flow impinging on the rollers, water evaporates from the paint, which increases the viscosity and prevents it from sinking as much paint into the printing ink and the printing substrate. By this measure, the paint application and thus the gloss of the printed product in the processing of low-viscosity paint is increased significantly in a surprising manner. Good results could also be achieved with the arrangement of a combined blowing and suction device (12) according to FIG. It has been found that by suction of the water vapor, the effect of the blowing air can be increased. The greatest effect could be achieved with heated blast air or combined radiation dryer and blown air with suction.

Thus, the embodiment is not limited to blown air, but their combination with a radiation dryer and suction and has been extremely beneficial to the viscosity increase of the paint.

Claims (2)

1. coating unit in offset printing machines with a rolling on a plate cylinder or paint form cylinder paint application roller, which is directly or via a transfer roller with a scoop roller in combination, characterized in that over the entire width of the roll extending pivoting blowing device (8) either in the immediate vicinity of the surface of the paint application roller (3), the transfer roller (2), the plate or paint forme cylinder (4.9) and the nip between the paint applicator roller (3) and plate or paint form cylinder (4.9) is arranged. 2. coating unit according to claim 1, characterized in that the blowing device (8) as a blowing and suction device (12) is formed.