DE1761736C - Dampening unit for an offset printing machine with a large number of nozzles arranged next to one another in the correct axis of the rollers of the printing unit - Google Patents

Description

within a predetermined range of the pressure

45 speeds are used, with this change

takes place in such a way that the pulse duration is longer at lower Druckgeschwindigktiten and at higher Printing speeds is faster.

The invention relates to a dampening system for another solution to the problem mentioned

an offset printing machine with a plurality of in 50 according to the invention characterized in that the Axial direction of the rollers of the printing unit in addition to the control device one per plate cylinder revolving around one another arranged nozzles, to which valves train changing the number of pulses emitted are arranged, which has inter-adjusting device by means of a control device, these emitting changes takes place at a rate of the printing speed in such a way that the number of revolutions per plate cylinder and a selectable factor-dependent number of 55 emitted number of impulses in the case of low impulses per plate cylinder revolution and with ren printing speeds higher and at higher selectable pulse duration are controllable, according to patent printing speeds is lower. 1611313. The invention is hereinafter based on the

Explained in more detail in printing tests with the above-mentioned FIGS. 1 to 3 of the drawing. The dampening system has shown that it is necessary to achieve 60 F i g. 1 shows the change numbers on the basis of a diagram a perfect print is advantageous, tion of the pulse duration of the spray pulses for the at lower printing speeds more liquid dampening depending on the printing speed to be added for dampening than at a higher rate;

Print speeds. This is essentially Fig. 2 shows three diagrams with pulses, their

on it, uaß at lower printing speeds 65 duration corresponding to the respective printing speed The color used for printing has a long time, density is different and

uuL-li on the non-printing, slightly from etching. Fig. 3 shows schematically a control device

Grainy surface parts of the pressure to control the valves of the nozzles.

3 4

In the diagram according to FIG. 1, on the pulse within the control device 3, the printing speed ν is multiplied and on the ordi- can be. With the ^B ™ ^telto f ^ * * ^ "" J nate the pulse duration A t for the spray pulse on-pulse duration of the individual pulses is set and carried. According to the continuously shown in the diagram z. B. with respect to the curve 1 found as opümal changes loaned the pulse duration. H 5 Pulse duration at production speed Mi which is proportional to the printing speed v. The setting handle 6 can be set with the selected example at different printing speeds ν 1, v2 and by how much the pulse duration AtI, AtI and At3 associated with the setting v3 handle 5 set pulse duration at initial net. - be extended print speed in place of the proportional dependence sol _(te p "_ between the pulse duration and the Druckgeschwin- io accordingly scheduled for this rotational speed may be aui optidigkeit also be other than the proportional value times found example, this VerAbhängigkeit between pulse duration and pressure. Iängerung in percent relative to the nraow tingeschwindigkeit in particular, be adjustable to be printed alternate handle 5 set value. papers can be advantageous. such other depend- by appropriate controls in the steuereinncngi ₃ ness is is with the dashed-line curve 2 i ₅ tung3 the In FIG. 1, three diagrams are shown which show the speed down to the smallest value at continuous printing speeds ν 1, .> 2 or ν3 corresponding to the printing speed ν changes soicne Meuer of the representation in Fig. 1 associated net si.id. In the elements you can either electrically or various diagrams over time, the ao also pneumatically or mechanically, the time of occurrence and the respective duration of the work. For example an electric acnai impulse could be shown. The printing speed vl device can be used with a servo motor and the corresponding pulses have the pulse duration Wl. on the one hand to one of the printing speed down - the pulse duration.! il is made up of the constantly rotating tacho generator and the other - pulse duration.f / 3 at the production speed a _{5 is} connected to a fixed voltage source. ν 3 and a further time segment, which is hatched, the voltage of which is shown partially over the slider one. In the example chosen here, the potentiometer is tapped, whereby the slider is connected to the pulse duration! / 1 at the initial printing speed of the servo motor ν3. ₃ o device 3 existing pulse generator in such a ver-According to the growing Druckgeschwindig- filters, that the pulse duration in said Bekeit according to the invention the pulse period III comparable area of the printing speed in the desired rings up to the pulse duration .1 / 3 in the continuation circumferential is changed. To achieve impulses print speed v3. For example, the atman pulses with a speed of a body at the printing speed ν2 in this 35-giger pulse duration are, in particular on the Ueb.et example, only a pulse duration .1 / 2, which gives the electronics many options that can be used for is SO «/ β greater than the pulse duration .1 / 3. - When implementing the concept of the invention, whoever production printing speed v3 is the pulse duration that can.

felt back to the value A / 3. To achieve one of the respective pressure

Since the pulse repetition frequency of the spray pulses depends on the speed of the offset printing machine

depends on the printing speed, dampening of the printing plate can appear instead of or

for example at the initial printing speed together with the change in the pulse duration of the

vl fewer spray impulses in the unit of time than with spray impulses also a change in the impulse

the production speed ν 3rd repetition frequency of the spray pulses

In Fig. 3, a control device3 is schematically 45 den, which is basically to the already by the

with operating handles 4, 5 and 6 shown. The change in printing speed is proportional

Operating handle 4 is used to set an occurring change in the pulse train frequency

correct factor by which that of, not shown, happens. - Such a change in the pulse scanners for the print speed repetition frequency has a similar success as the or speed of the printing rollers emitted Im- 50 before the change in the pulse duration described.

1 sheet of drawings

Claims (2)

n ... plate to arrive. Therefore, with lower printing claims: gSpeed relatively more dampening solution supply 1. Dampening system required for an offset printing press than for higher printing speeds with a large number of in the axial direction of the wall always a sufficient separation of color and zen of the printing unit to ensure 5 dampening solutions arranged side by side. Bet bigger pressure nozzles, to which valves are assigned, the means of speeds is relatively less dampening solution one Control device intermittently with a zuuhi required to provide the necessary separation of on the printing speed and a selectable ink and dampening solution to maintain. Baren factor-dependent number of pulses Furthermore, it is known that an offset printing machine per plate cylinder revolution and with a selectable io when printing a product only after an «an- Pulse duration controllable, according to patent 1611313, geren start-up time their highest printing speed. characterized in that the control reaches the so-called form pressure speed, device (3) two effects on the pulse duration The printing process begins with a certain Kende adjusting devices (5, 6) has, from th initial printing speed, which is a low which are the one setting device (5) for a fraction of the production speed position of the pulse duration at a certain can. Increasing the printing speed of Print speed and the other setting before the initial print speed except for the cont direction (n to change the pulse duration printing speed can play a considerable part compared to that of the one setting device of the entire, for printing the edition of a product (5) the set value within a predetermined time expended. The during J th range of printing speeds dHnt, this start-up time printed products are to this change takes place in such a way that the mostly so-called waste, because during dei Pulse duration at lower printing speed - start-up time the ratio of the ink addition to the moisture times longer and at higher printing speeds of the printing plate not the respective pressure is shorter. 25 speed is adjusted, but only to: 2. The dampening system for an offset printing machine selects the previously determined production speed is directed with a large number of in the axial direction of the WaI-. zen of the printing unit arranged side by side The invention is therefore based on the object. Nozzles to which valves are assigned, which by means of always the right Vei a control device intermittently with a ratio of ink addition and dampening solution supply from the printing speed and one depending on the printing speed to be adhered to and factor-dependent number of impulses in particular the accumulation of waste during de, per plate cylinder revolution and with a selectable start-up time and during the shutdown of the printing pulse duration are controllable, according to patent 1611313, significantly reduce the machine, characterized in that the control device 35 A solution to the problem mentioned is in a device (3) a dampening unit of the type mentioned above that is thereby given off per plate cylinder revolution Number of pulses changing indicates that the control device has two on the Having adjusting device, this change in pulse duration acting Eipsiellvorrichtungen takes place in such a way that the per plate cylinder has, one of which is an adjusting device for single rotation number of pulses delivered 40 setting of the pulse duration at a certain pressure lower print speeds higher speed and the other adjustment device and at higher printing speeds lower to change the pulse duration compared to that of ger is. the value set in a setting device