GB2044678A

GB2044678A - Dampening Device for a Printing Machine

Info

Publication number: GB2044678A
Application number: GB8007161A
Authority: GB
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1979-03-13
Filing date: 1980-03-03
Publication date: 1980-10-22
Also published as: JPS55164163A; SE8001217L; DE2909765A1; GB2044678B; IT1127393B; IT8048141A0

Abstract

A dampening device for an offset rotary printing machine comprises a fountain roller (1) rotating at a first surface speed and an inking roller (4) rotating at a second surface speed. A transfer roller (3) is provided between the two, and is driven by frictional contact with the inking roller (4). The inking roller 4 is driven by frictional contact with the plate cylinder (5) and a positively driven ink distribution roller (6). The fountain roller (1) is driven from the transfer roller (3) by means of a drive transmission. In this way, the surface speeds of the transfer roller (3) and the fountain roller (1) can adapt automatically to any alteration in the surface speeds of the plate cylinder (5) or the ink distributor roller (6), without the necessity for additional control devices. The drive transmission may be by toothed gearing, or by a belt. The fountain roller 1 may be provided with a brake to allow adjustment of its rotation. <IMAGE>

Description

SPECIFICATION Dampening Device for a Printing Machine This invention relates to a dampening device for a printing machine.

German Patent Specification 1,411,118 discloses a dampening device for an offset rotary press, with a water fountain roller rotating at a first surface speed and an inking roller rotating at a second surface speed, which lies against a positively-driven ink distributor roller and a plate cylinder, and with a transfer roller which transports the dampening fluid from the water fountain roller to the inking roller. The water fountain roller is driven by means of its own motor. The water fountain roller in turn actuates the transfer roller via gearwheels.

In another dampening device, known from German Offenlegungsschrift 2,230,430, the water fountain roller and the transfer roller each have their own driving motor.

Such known dampening devices thus require at least one driving motor for the water fountain roller.

The present invention aims to provide a dampening device which is susceptible to relatively low cost construction.

According to the present invention, there is provided a dampening device for an offset rotary printing machine having a plate cylinder and a positively driven ink distributor roller, the device comprising: an inking roller which is arranged to be driven by frictional contact with the plate cylinder and ink distributor roller of a printing machine; a fountain roller; a transfer roller arranged to transfer dampening fluid from the fountain roller to the inking roller, and being arranged to be driven by frictional contact with the inking roller; and a drive transmission between the transfer roller and the fountain roller for driving the fountain roller from the transfer roller.

Thus, no separate driving motor need be provided for such a dampening device.

A further advantage of such a dampening device may be that the surface speeds of the transfer roller and the fountain roller may adjust automatically to changes in the surface speeds of the plate cylinder or ink distributor roller of a printing machine in use, without an additional control device being necessary.

In a development of the invention, a brake is attached to one of the rollers connected by means of the drive transmission. Thus, by altering the braking force, further manual adjustment may be made in addition to the above-mentioned automatic regulation of the supply of dampening medium.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing, in which: Figure 1 is a schematic side-view of a dampening device for an offset rotary printing press; and Figure 2 shows a drive transmission for the device of Figure 1.

The illustrated dampening device comprises a water fountain roller 1, which partly dips into a water fountain 2 containing dampening fluid, and which has an elastic outer surface, e.g. made of rubber.

A transfer roller 3 lies against the water fountain roller 1, which transfer roller 3 is expediently equipped with a metallic, waterabsorbent outer surface. The transfer roller 3 interacts with an inking roller 4, which again has an elastic outer surface. In the working position shown in Figure 1, the inking roller 4 lies not only against a plate cylinder 5 but also against an ink distributor roller 6. Means which are in themselves known, and not illustrated, e.g.

mounting of the inking roller 4 on rocking levers or in eccentric bearings, serve for the adjustment of the contact pressure of the inking roller 4 on the plate cylinder 5 and on the ink distributor roller 6, and for bringing it into or out of cooperation with the plate cylinder 5. Ink is fed to the ink distributor roller 6 via the rollers of an inking device, which are known and not illustrated.

The water fountain roller 1 is mounted on a shaft 9, which is mounted at each end in a leverlike part of a support 7. The support 7 is mounted rotatably at a pivot point 8, which is aligned with the shaft 9, to the side walls of the printing machine, which are not illustrated. The transfer roller 3 is mounted on a shaft 10, which is mounted at each end in an eccentric bearing 11.

The eccentric bearings 11 are arranged in the support 7, and serve to permit adjustment of the nip between the water fountain roller 1 and the transfer roller 3.

The support 7 can be rotated around the pivot point 8 by means of an hydraulic or pneumatic adjustment device 12. A set screw 14, which is screwed into a solid support piece 13, serves to determine the working position of the support 7, and thus to determine the pressure between the transfer roller 3 and the inking roller 4. The support 7 can be alternatively movably mounted, and it is also possible to actuate and stop the rollers 1 and 3 by hand.

As can be seen from Figure 2, a gear wheel 15 is rigidly attached to the shaft 10 of the transfer roller 3. The gear wheel 1 5 meshes with a further gear wheel 16, which is rigidly attached to the shaft 9 of the fountain roller 1. It is advantageous that the diameters of the gear wheels 1 5, 16 are such that the surface speed of the water fountain 1 is lower than the surface speed of the transfer roller 3.

Instead of this gear train, another known drive transmission, such as a V-belt drive, can be used.

In this case, the further possibility exists of making the transmission ratio variable, by means of oppositely directed alteration of the diameters of the two belt pulleys driving the V-belt, by means already known per se.

A brake pressure plate 1 7 is also attached to the shaft 9 of the water fountain roller 1. A brake shoe 18, mounted in guides 19, can be urged against the circumference of the brake pressure plate 17. A set screw 21, which can be screwed through a rigid support piece 20, serves for this purpose. The rates of revolution and thus the surface speeds of the water fountain roller 1 and the transfer roller 3 can be decreased by adjustment of the brake. Any known type of brake arrangement can be used as an alternative to the brake shown.

If the plate cylinder 5 and the ink distributor 6, which are both driven by a main driving motor of the printing machine, turn while in operation, the inking roller 4 follows this turning movement as a result of entraining by friction contact. As a result of the transfer roller 3 bearing against the inking roller 4, the transfer roller 3 is also entrained by friction contact. The turning movement of the transfer roller 3 is then transferred via the gear train 15, 16 to the water fountain roller 1.

If it should turn out that too much dampening fluid is being fed to the plate cylinder 5 in the case of a particular subject or a particular rotational speed of the machine, the rotational speed of the water fountain roller 1 and the transfer roller 3 can be reduced by more or less powerful application of the brake shoe 1 8 to the brake pressure plate 1 7. In this way, less dampening fluid is fed to the plate cylinder 5. It is not necessary for this purpose to adjust the nip between the water fountain roller 1 and the tranfer roller 3 or to alter the pressure force between the transfer roller 3 and the inking roller 4.

If the rotational speed of the plate cylinder 5 and thus the rotational speed of the ink distributor roller 6 should alter during operation, the inking roller 4 and thus the transfer roller 3, as well as the water fountain roller 1, will follow this alteration in speed without requiring the actuation of any adjustment or regulation process. Since the brake only needs to apply a very low braking force, it is also subject to very little wear.

Claims

1. A dampening device for an offset rotary printing machine having a plate cylinder and a positively driven ink distributor rolier, the device comprising: an inking roller which is arranged to be driven by frictional contact with the plate cylinder and ink distributor roller of a printing machine; a fountain roller; a transfer roller arranged to transfer dampening fluid from the fountain roller to the inking roller, and being arranged to be driven by frictional contact with the inking roller; and a drive transmission between the transfer roller and the fountain roller for driving the fountain roller from the transfer roller.

2. A dampening device according to claim 1, wherein the drive transmission comprises two gear wheels which mesh together.

3. A dampening device according to claim 1, wherein the drive transmission comprises a V-belt drive.

4. A dampening device according to claim 1, 2 or 3, wherein the drive transmission has a transmission ratio other than unity.

5. A dampening device according to claim 4, wherein the transmission ratio is adjustable.

6. A dampening device according to any one of the preceding claims, wherein a brake is attached to one of the transfer and fountain rollers.

7. A dampening device substantially as hereinbefore described with reference to the accompanying drawing.

8. A printing machine having a dampening device according to any preceding claim.