FR2782469A1 - Wetting system for printing machine - Google Patents

Abstract

The wetting system is provided for a printing machine with a plate cylinder (1) carrying a printing block. The cylinder is in operative connection with adjustable rollers of an inking mechanism and of a wetting system. The latter has a wetting supply unit with a wetting dispensing unit. The supply unit has a moisture duct (7) which dips into a wetting means container (14). A spray device (9) for spraying gum is provided to apply gum to the surface of the moisture duct. The wetting supply is separable by a gap (13) from a wetting roller (6) associated with the plate cylinder.

Description

The present invention relates to a wetting unit for a machine

  printing, comprising a plate cylinder carrying a

  plate, which is in functional connection with application rollers

  of an inking unit and a mooring unit, which pre-

  feels a device for supplying wetting fluid with a device for

wetting fluid dosage.

  A wetting unit of this type is known from the document DE-

  29 205, as part of a printing unit. A cy-

  The plate holder liner also carries a plate and is in functional connection with adjustable application rollers, an inking unit and a wetting unit. The wetting unit has, among other things, a wetting fluid application roller, which is arranged downstream of a wetting fluid supply. In this case, the wetting fluid supply is formed by a wetting roller plunging into a container of fluid

  as well as by a metering roller.

  By the instructions for use (1978 edition, p. 7.24) for a machine

  printing machine type Roland 800 (series 818) from MAN Roland Druckmas-

  chinen AG, Offenbach, it is known that, to rubberize a plate fixed on the plate cylinder, the application of the rubberizing liquid is carried out on the plate via the rollers of the wetting unit. In addition, a diluting liquid diluted in water is supplied by means of a jet flask on the dosing roller. In addition, it is recommended that,

  for photos with sensitive print media,

manual mage is still performed.

  To erase a cliché on a plate cylinder, it is in-

  be known from patent EP-0 453 854, inter alia, to associate with the roller for applying wetting fluid, a dip roller for rubberizing

  submerging in a tank filled with liquid of rubber. In a development

  loppement, there is arranged, between the plunger roller and the dampening fluid application roller, a roller for dampening fluid. During the exposure of the plate, the connection between the roller for applying wetting fluid and the supply device

  wetting fluid placed upstream is interrupted or can be

  set to the smallest possible amount of wetting fluid. It is known, for example from document DE-195 29 205, that printing ink can accumulate on the fluid application roller

  anchor, which is transported via the undercarriage

  leaux, in the wetting unit, in particular the wetting fluid supply device. This affects the ink / wetting fluid balance,

  is expressed in the form of spots or streaks and causes an emulsion.

  The object of the invention is to provide a wetting unit of the type

  previously described which avoids the disadvantages mentioned, which allows, in part

  particular, stable wetting during the process, and significantly reduced

  ink return in the wetting unit.

  To this end, the wetting unit for a printing machine, of the type indicated above, is remarkable, according to the invention, in that the wetting fluid supply device has a wetting roller immersed in a container. of dampening fluid, and in that, for applying a coating to the envelope surface of the dampening roller, a spraying device for a dampening agent is associated with this dampening roller, the device for supplying fluid wetting agent which can be separated from a roller for applying

  wetting associated with the plate cylinder in a slot location.

  Advantageously, between the dampening roller and the spray unit

  verification, there is a metering roller associated, in contact, with the wetting roller, the spraying device being oriented towards the

metering roller.

  Furthermore, the spraying device can be arranged in the

wetting fluid container.

  In addition, the spraying device can be arranged downstream, in functional connection, from a duct system, a pump or the like.

  feeding means, as well as a container of glaze agent.

  Furthermore, to apply a rubber coating to the dampening roller and / or the metering roller, the reservoir of dampening fluid in the container of dampening fluid can be removed or, at least, it

  can be set to a low level of wetting fluid.

  Advantageously, after the application of a rubber coating, the roller

  metering unit is moved away from the dampening roller.

  Preferably, at least the pump or other supply means

  is coupled by a circuit technique to a machine control.

  In addition, the direction of supply of the pump or supply means

statement can be reversed.

  A first advantage of the solution according to the invention consists in that, by rubberizing a wetting roller as well as, if necessary, a metering roller associated by means of a spraying device, the ink build-up in the dampening unit is reduced so

  sensitive, and in that the necessary ink / wetting fluid balance

  while the printing process is stable.

  It is more advantageous that the wet roller rubber

  The metering or the metering roller can be carried out independently of the material.

  rollers used. So for example a dampening roller

  and / or a metering roller with a chrome surface can be engom-

  mé as well as a roller having a ceramic surface. In addition, an advantage is that, thanks to the rubberised dampening roller or

  to the metering roller, the return of the printing ink from the applicator roller

  Wetting fluid cation in the wetting fluid container, which results in an emulsion, is prevented. The wetting roller plays a double role in that, during the printing, the supply of the wetting fluid to the roller for applying the wetting fluid is possible and, simultaneously, the return of the printing ink being on the envelope of the wetting fluid application roller in the wetting fluid container is significantly reduced. In the case of a roller train of a wetting unit having a metering roller arranged between the wetting fluid application roller and the actual wetting roller, the metering roller

plays this dual role.

  By coupling with the machine control, the process

can be automated.

  A desiccant drying in the spraying device, a duct system, as well as a pump or a switching valve, can be carried out by reversing the feed direction.

of the rubberizing agent.

  As a coating agent for the preservation of surfaces,

  advantageously uses aqueous solutions, for example colloids.

  The best known agent is gum arabic.

  The single figure of the appended drawing will make it clear how the invention can be carried out. In this figure, a unit of

  wetting for an offset printing machine.

  An inking unit having ink application rollers 3 is associated with a plate cylinder 1. In addition, the plate cylinder 1

  is coupled to a blanket cylinder 2 of an offset printing unit.

  The other subsets of the printing unit will not be detailed here.

  if we. In the direction of rotation of the plate cylinder 1, a wetting unit is arranged upstream of the inking unit. The wetting unit consists, in the present example, of a wetting fluid container 14, of a wetting roller 7 immersed in the wetting fluid container 14, of an associated metering roller 8 to the wetting roller 7, as well as to a roller for applying wetting fluid 6 adjustable relative to the plate cylinder 1. The container 14 for wetting fluid and the wetting roller 7 form the supply device for wetting fluid, and the metering roller 8 forms, in the direction of rotation of the wetting roller, before the fluid application roller

  wetting agent 6, the very thin film of wetting fluid. The roll of ap-

  plication of wetting fluid 6 is associated, in contact, with a bridging roller 4, which is switchable to a neighboring ink application roller 3, so that the wetting fluid application roller 6 and the first ink application roller 3 can be bridged as desired. A

  wandering roller 5, also known as a tandem roller, is furthermore

  placed downstream of the wetting fluid application roller 6 in its direction of rotation after the bridging roller 4. The bridging roller 4 and

  the wandering roller 5 are preferably produced by having a driving

  reversible axial, as well as a rotary drive, as a

  ink supply waters. In a preferred embodiment, the bridging roller 4 and the wandering roller 5 have a surface receiving the

wetting fluid.

  In a simple embodiment, the fluid supply device for

  dampening is formed by the dampening roller 7 dipping into the recess

  pient 14 of wetting fluid. To apply an exfoliation on the

  envelope face of the wetting roller 7, a spraying device 9 for the glueing agent is associated therewith, the wetting fluid supply device being separable from the application roller

  wetting fluid 6 in a slot 13.

  In one development, the spraying device 9 is associated with the wetting roller 7 and / or with the metering roller 8 adjacent to the wetting roller 7. Likewise, the wetting unit can be made so that, between the wetting 7 and the spraying device 9, there is arranged the metering roller 8 associated, in contact, with the wetting roller 7, the spraying device 9 being oriented towards the

dosage 8.

  In this case, the spraying device 9 is coupled to a system

  conduit 10 for the rubberizing agent. A pump 1 1 or another

  three supply means, as well as a container of sintering agent 12 are arranged upstream of the duct system 10. The pump 11 serves as a metering pump for bringing the sintering agent to the agent container to the spraying device 9. As an alternative to the pump 11, the supply of the spraying agent can be carried out by compressed air, under the control of a switching valve. Furthermore, the pump 1 1 or other means can be reversed, so that the rubberizing agent remaining in the spraying device 9

  as well as in the duct system 10 can be drawn back into the container

pumice agent 12.

  To apply the coating on the dampening roller 7, the roller

  the wetting water 7 can be decoupled from the wetting fluid application roller 6 at the slot location 13. Depending on the geometry of the train of rollers, other rollers, adjacent to the wetting fluid application roller 6, as transfer rollers, metering rollers, can be decoupled from the wetting fluid application roller 6 at the slot location 13. In this case, the wetting fluid is emptied from the wetting fluid container 14 ( through the outlet) or at least lowered to a very low level of wetting fluid. Alternatively, the container

  wetting fluid 14 can also be lowered so that the roller

  the wetting water 7 is no longer in contact, generally, with the wetting fluid. The spraying device 9 is preferably arranged so that

  integral with the frame and is oriented directly towards the surface of the

anchor roller cover 7.

  In the development where the metering roller 8 is oriented towards the envelope surface, the spraying device 9, taking into account

  of the geometry of the train of the dampening rollers, must be advantageous

  also arranged on the formwork of the machine. When applying

  ingestion on the metering roller 8, the cut-off point 13

  relative to the roller for applying wetting fluid 6 is retained.

  Alternatively, the spraying device 9 with the system

  conduit 10 (and the pump 11 or the supply means arranged

  upstream, as well as the container of sintering agent 1 2) can be arranged

  this is integrated in the wetting fluid container 14. Before applying the coating on the wetting roller 7, the

  wetting must be removed from the wetting fluid container 14 before

  by emptying. Also in this arrangement, to apply the coating on the dampening roller 7, the cut-off point 13 by

  relative to the wetting fluid application roller 6 is retained.

  Spray device 9 and pump 11 or other means

  can be reversed and coupled to a ma-

  china, for example a control station, so that the application of a rubberizing agent on the wetting roller 7 as well as the rebreathing of the excess rubberizing agent in the container of rubberizing agent 12

  can be performed according to an automated process.

  The application of the rubber coating as a thin protective layer

  on the dampening roller 7 or on the metering roller 8 prevents

  builds up on the dampening roller 7 or the metering roller 8, which can otherwise occur through the return of ink. In particular in the case of dampening rollers 7 made of special materials, such as for example chromium or ceramic, it is moreover guaranteed, with respect to the surface of material which does not accept ink, a stable wetting at

  during the process by applying the rubber coating.

  To avoid drying of neighboring rollers, the metering roller 8

  can be moved away from the dampening roller 7 after applying the rubber

mage.

Claims (8)

  1. Wetting unit for a printing machine, comprising a plate cylinder carrying a plate, which is in functional connection with adjustable application rollers of an inking unit and a wetting unit, which presents a wetting fluid supply device with a wetting fluid metering device,   characterized in that the wetting fluid supply device pre-   feels a wetting roller (7) plunging into a container (14) of wetting fluid, and in that, to apply a rubber coating on the   envelope surface of the dampening roller (7), a spraying device   sation (9) for a coating agent is associated with this wet roller   lage (7), the wetting fluid supply device being separable from a wetting fluid application roller (6) associated with the cylinder   plate holder (1) in a slot location (13).   2. wetting unit according to claim 1,   characterized in that between the dampening roller (7) and the pulverizing unit   verification (9), a metering roller (8) is arranged associated, in contact, with the wetting roller (7), the spraying device (9) being oriented to the metering roller (8).   3. wetting unit according to claim 1, characterized in that the spraying device (9) is arranged in the   wetting fluid container (14).   4. wetting unit according to one of claims 1 to 3,   characterized in that the spraying device (9) is arranged downstream, in functional connection, of a duct system (10), of a pump (11) or of another supply means, as well as of '' an agent container (1 2).   5. wetting unit according to one of claims 1 to 4,   characterized in that, in order to apply a coating to the dampening roller (7) and / or the metering roller (8), the reservoir of dampening fluid in the container (14) of dampening fluid can be removed or, at the less, it can be set to a low level of wetting fluid. 6. Wetting unit according to claim 2, characterized in that, after the application of a rubber coating, the roller   dosing (8) is distant from the wetting roller (7).   7. wetting unit according to claims 1 and 4,   characterized in that at least the pump (11) or the other supply means   tation is coupled by a circuit technique to a control of ma-   China. 8. wetting unit according to claim 7, characterized in that the direction of supply of the pump (1 1) or the   feeding means can be reversed.