DE2031960C - Alcohol-based dampening system on sheet-fed rotary offset printing machines - Google Patents

Description

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The invention relates to a dampening system of sheet-fed rotary offset printing machines working with the addition of alcohol.

When dampening printing plates, it is known to be difficult, especially with smooth papers, to distribute a small amount of moisture evenly on the plate. As little wet liquid as possible but is desirable because of the ability of the print carrier to attract water and the danger of the «> Emulsification of paint and water that cause color fluctuations. To remedy this deficiency, if alcohol has already been added to the fountain solution, it reduces the surface tension of the fountain solution decreased, the wettability and the evaporation rate of the same increased and thus enables the amount of fountain solution to be reduced. However, this has a disadvantageous effect so-called alcohol dampening units from the fact that when the machine is down, the dampening rollers and moisture located on the plate evaporates quickly and then the dampening roller from the plate Takes on color and gives it back to the plate, so that scumming occurs. In order to restart the Machine to restore the color-water balance quickly and through rapid evaporation To prevent ink from being released from the dampening roller to the plate, it is necessary to pre-wet. In practice, for example, this is done by hand from the printer over the roller of the dampening system is carried out. On the other hand, it is also known to be on dampening system based on the siphon principle (magazine: Deutscher Drucker dated 10.8.1967, page 23) with the dampening form roller switched off from the plate cylinder by means of a number of Feuchtträgerhüb- Feucht to apply liquid to the dampener, from which in turn the dampening application roller thus ge is fed. However, the preprogramming of such a pre-moistening requires a considerable amount of work wand (German Patent 1,279,690).

The object of the invention is to create a device on dampening units which, in a simple manner of operation and with little effort, pre-moistening fire units of sheet-fed rotary presses using alcohol. ι printing machines after machine downtimes _;

light.

According to the invention this is achieved by that in addition to the unliehen dampening system for the W-r a known spray dampening system is seen, the rays of this spray dampening Werk from above i "the gap between Feuchtaul tragsualze and the dampening of the usual Feucht are directed at the factory. With this measure win.! a sound when restarting the machine fast! eliminated and thus the amount of waste is reduced because the dye quickly restores the water balance is provided.

From the USA. Patent specification 2,798,426 is a device for dampening offset printing for ar men known in which an additional dampening unit on the plate cylinder in addition to the actual dampening unit is provided. However, alcohol is not used and J'C manual actuation With the additional device, only an uncontrollable moisture impact can be carried out.

In the dampening system known from German patent specification 883.288 with two dampening devices in turn, the dampening device that works together with an inking roller is only activated optionally place the dampening system working separately from the inking unit on the Plattenzy cylinder effective.

There are also methods for dampening printing plates known (German utility model 6,602,322 and 6,602,778). where the wet liquid is injected between two rollers. These dampening systems are not in addition to the Usual dampening undertaking dampening systems ver used and are also not in accordance with the invention arranged for this purpose.

According to a preferred embodiment of the inventor application can be measured by a time relay or the like, the spray duration so that both the on support roller as well as the plate itself with one sufficient appropriate moisture film are provided.

An exemplary embodiment of the invention is shown in the drawing. It shows:

1 shows a plate cylinder with part of the inking unit and the dampening unit according to the invention schematic,

F i g. 2 a front view in a schematic representation,

Fig. 3 shows a detail.

In the direction of rotation of the plate cylinder 1 of a printing unit in front of the inking rollers 2, 3, 4, 5

in a known manner from one in a humid container 6 running ductor roller 7, a lifter 8, a 'euchtreiber 9, the dampening form roller 10 and a storage roller II existing dampening system is arranged during operation that is used for printing required dampening liquid through the between the ductor roller 7 and the traversing dampening driver 9!. Reciprocating lift 8 supplied. After machine shutdowns, the alcohol-enriched is due to the rapid evaporation The dampening liquid on the storage roller 11, which has a compensating effect, is no longer sufficient dampening liquid and thus no longer on the dampening form roller 10.

In order to achieve the necessary for a perfect print result as quickly as possible when restarting Establish water-color balance in the space between the dampening form roller 10, A number of nozzles 12 distributed over the width of the machine are provided for the dampening driver 9 and storage roller 11, through which the dampening liquid on the dampening detection roller 10 and the adjacent to it Moisture driver 9 is sprayed on when starting up.

This can be done in a simple manner, for example, as shown in FIG. 3, by a number of riser pipes 13 which are immersed in a moist liquid container It and are each arranged at the mouth of an air pipe 15 in the manner of an injector. Due to the speed of the air emerging from the air tubes 15, sufficient liquid is transported from the wet liquid container 14 through ₄

- u ii owauet and on the applicator roller 5 Si ^ uU sighted subdivision of the 10 blown uu arrangement of ab-

Air collecting pipe 16 una · _{biscuit zones} .

η ITo 2 aargeVtellt. The Feuchtflüssigke.t is "^ nruckMssigkeitsbehälter taken 17 and emem ™« J ³ ^ _{1 eigten} four zones trains through the ^Ve * '' doing _it ⁶ £ _dab egg, f * this tax to arrange "S, so

18 given

at the

one

Ξ, dampening form roller 10 and dampening driver 9 as ₁ s Specher and 'gelanj gradually on the flap cylinder without a momentary excess aut

With appropriate measurement of the pre-moisture direction, this can also be used as the main spray dampening unit that replaces the lifter will.

1 sheet of drawings

Claims (6)

Patent claims: 1. The dampening system of sheet-fed rotary offset printing machines that works with the addition of alcohol, d a through characterized in that in addition to the usual dampening system for pre-dampening a per se known spray dampening unit (12) is provided, the rays of this spray dampening unit from above in the gap between the dampening form roller (10) and the dampening driver of the usual dampening unit ι ο (7 to 11) are directed. 2. Damping unit according to claim 1, characterized in that the spray device consists in a known manner of a number of riser pipes (13) which dew into a Feuchtiquidkiitsbehälter (14) i 'chen, whose mouths in the manner of an injector to those of compressed air leading air tubes (15) ^r angeo are dnet. i. A dampening system according to claims 1 and 2, characterized in that the air pipes (15) are connected in a known manner to Luftsai.nmelrohre (16) and the flow in each collecting pipe can be regulated by a valve (18). 4. dampening system according to claims 1 to 3,.?> characterized in that the regulation of the valves (18) from the boom by remote control tion takes place. 5. Feuchtwei ¹ 'according to claim 1, characterized in that the nozzles 02) are connected to a pressurized fluid container (17) and are zonally sieuer ^ ar. 6. dampening system according to claims 1, 2 and 5, characterized in that the valves (18) by timing relay when starting automatically control '< are cash.