Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F21/00—Devices for conveying sheets through printing apparatus or machines
  • B41F21/04—Grippers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F7/00—Rotary lithographic machines
  • B41F7/02—Rotary lithographic machines for offset printing
  • B41F7/04—Rotary lithographic machines for offset printing using printing units incorporating one forme cylinder, one transfer cylinder, and one impression cylinder, e.g. for printing on webs
  • B41F7/06—Rotary lithographic machines for offset printing using printing units incorporating one forme cylinder, one transfer cylinder, and one impression cylinder, e.g. for printing on webs for printing on sheets

Definitions

• the invention relates to a sheet-fed rotary offset printing press with at least one printing unit, which contains a rubber cylinder provided with a cylinder pit, with which, on the one hand, a plate cylinder which can be acted upon with ink and dampening solution and also provided with a cylinder pit, and on the other hand, also a cylinder pit in which Grippers are arranged, interacting counter-pressure cylinders.
• REPLACEMENT LEAF find that can lead to the aforementioned bulge. "" The consequence of this would be the risk of so-called greasing, since the bead can come into contact with the rubber cylinder outside the pressure area. In addition, there could be severe wrinkling. In this context, it can be assumed that slight folds cannot be avoided in the folded area of folded products. In the known arrangement in which printing is carried out close to the edge, these folds would be rolled out and thus enlarged.
• this object is achieved in that at least one printing unit - as with
• REPLACEMENT LEAF Multi-layer products feedable impression mechanism is formed, in which the rear edge of the cylinder pit of the rubber cylinder follows the rear edge of the cylinder pit of the impression cylinder more than is necessary to avoid a collision with the grippers, in which the impression cylinder in the inlet area effective hold-down device is assigned to the pressure zone between the blanket cylinder and counter-pressure cylinder, and in which the circumference of the counter-pressure cylinder is spaced from the circumference of the blanket cylinder depending on the thickness of the multi-layer products.
• the rear edge of the cylinder pit of the rubber cylinder can follow the rear edge of the cylinder pit of the impression cylinder by at least 12 mm, preferably by 15 mm to 20 mm.
• this wake ensures that wrinkles do not roll out reliably and, on the other hand, also results in a pressure application which is within the scope of what is useful in the case of impressions.
• a further expedient further development of the superordinate measures can consist in the fact that the hold-down device is designed as a spring-loaded pressure element. In an advantageous manner, this can simply go over the grippers of the counter-pressure cylinder, so that no air pockets can form.
• the size of the distance between the blanket cylinder and the counterpressure cylinder can be below, preferably 5% to 15% below, the thickness of the multi-layer products. On the one hand, this ensures that there are no constraining forces between the cylinders. Nevertheless, the products are reliably pressed, which is advantageous for achieving quality printing.
• a particularly simple measure for achieving the relieving Zy ⁇ distance ' may be that the diameter of the impression cylinder relative to the diameter of the blanket cylinder simply reduced to the desired level
• REPLACEMENT SHEET is. This measure is particularly recommended when converting existing machines to impression machines, since the cylinder bearing can be retained.
• the rubber cylinder can also expediently be covered with a film which has a rubber covering which is preferably glued on only in the indentation area. With this measure, undesired lubrication can be further prevented. At the same time, this results in easier control of the dye and dampening solution. In this context, it can also be advantageous to adapt the effective width of the inking unit and the dampening unit to the width of the impression.
• a further, particularly preferred measure can consist in that the counter-pressure cylinder is preceded by a stretching device which comes into engagement with the bottom sheet of the product being fed. It is hereby achieved that the multilayer products are also stretched in the area of their underside, which comes into contact with the cylinder circumference of the impression cylinder, which further prevents wrinkling. This measure can be used in a particularly advantageous manner in the production of a perfecting print.
• This consists, in a manner known per se, of a PJatten cylinder 3, a Gu ⁇ i cylinder 4 and one Counter pressure cylinder 5.
• These cylinders are provided with cylinder pits 6, 7, 8.
• tensioning devices 9, 10 for the printing plate 11 and the rubber blanket 12.
• the plate cylinder 3 is supplied by an inking unit 14 with ink and a dampening unit 15 with dampening solution.
• the impression cylinder 5 interacts with a delivery drum 16, which here is gripped by a delivery belt 17. This can be with "a separate drive to be equipped •! Therefore be selectively driven so as to be a Schup ⁇ designed from egten products in the form penstroms or L .izelexe plare.
• the impression unit 2 is connected via a feed table 18, which is designed here as a belt table.
• this is a so-called cassette feeder which has a shaft 21 which can be loaded from above and holds a stack 20 of products 1, the bottom of which is designed as a removal belt 22 through which products 1 can be removed individually and the feed table 18 can be fed.
• the sides and front marks, not shown here, and pre-grippers or infeed rollers can be provided, of which the grippers 13 of the counter-pressure cylinder 5 take over the products 1 and through the gap between the rubber cylinder 4 and Guide impression cylinder 5 through.
• the plate cylinder 3 and the blanket cylinder 4 have the same effective diameter D.
• the extension drum 16 also has this diameter.
• the impression cylinder In normal sheet-fed rotary offset printing machines for printing on individual sheets, the impression cylinder generally also has approximately the same diameter and its circumference lies against the blanket cylinder. As the products 1, but considerably thicker than ein ⁇ zelne sheet are /, in the present imprinter the circumference of the impression cylinder 5 is the cylinder 4 distanced so far from the periphery of the Gummi ⁇ that a relative to the thickness of the products 1 slight undersize having Direction gap 23 results . The clear width of the gap 23 can decrease the thickness of the products 1 by about 5% to 15%. An undersize of 10% should be provided here.
• the counter-pressure cylinder 5 is simply with a correspondingly smaller diameter than the rubber cylinder 4 and the plate cylinder.
• linder 3 provided. This can be achieved, for example, by turning the impression cylinder of a normal sheet-fed rotary offset printing machine accordingly. This is particularly recommended when converting existing sheet-fed rotary offset printing presses to impression presses according to the invention, since the cylinder bearing can be retained.
• the impression cylinder 5 it would also be conceivable for the impression cylinder 5 to be detachable from the blanket cylinder 4 while maintaining its engagement with the delivery drum 16 and / or for the blanket cylinder 4 to be detachable from the impression cylinder 5 while maintaining its position relative to the plate cylinder 3. In such a case, an individual adjustment of the size of the gap 23 would be possible.
• there is a fixed gap setting which is sufficient for many applications in which products of known thickness are processed.
• the grippers 13 project beyond the circumference of the counter-pressure cylinder 5 by the thickness of the products 1, so that they can be reliably detected. In the case of a rotated counter-pressure cylinder, this can be achieved simply while maintaining the grippers.
• Air can be located between the individual layers of the multi-layer products 1. This must be removed to create a clean print.
• the products 1 are pressed onto the counter-pressure cylinder 5 by means of a hold-down device 24 arranged in the inlet area to the pressure zone between the material cylinder 4 and the counter-pressure cylinder 5.
• the hold-down device 24 can have a spring-loaded pressure plate that extends over the entire length of the cylinder and under which the grippers 4 can pass.
• the hold-down device 24 is provided with a gap for the resilient comb plate 25 forming the grippers 13. This can be arranged stationary.
• the comb plate 25 is arranged pivotably and can be brought into and out of holding engagement in cycles by means of a cam control 27 cooperating with a spring 26. This cyclical actuation of the hold-down device 24 results in a particularly gentle operation.
• the holding-down device 24 With the help of the holding-down device 24, the products 1, as can be clearly seen in the drawing, are not only stripped and pressed against the counter-pressure cylinder 5, but at the same time also kept away from the rubber cylinder 4, thus eliminating the risk of lubrication.
• the hold-down device 24 also causes the upper layers of the products 1 to be stretched.
• a stretching device is provided in the area of the contact table 18, which extends to the lower one Able to apply a braking force.
• blowing nozzles 28, which are inserted into the feed table 18 and are provided against the transport direction of the products 1, are provided for this purpose and are supplied with compressed air via a supply line 29, whereby the hydrodynamic paradox can develop.
• blowing nozzles could of course also on
• REPLACEMENT3LATT a vacuum source connectable suction nozzles can be provided.
• the stretching device is controlled in such a way that the braking force is only effective when the products 1 are transported by the grippers 13.
• the cylinder pits 7 and 8 of the rubber cylinder 4 and the impression cylinder 5 do not run with their edge edges on one another. Rather, the rubber cylinder 4 runs after the impression cylinder, as indicated by the caster angle N.
• This caster dimension is greater than would be absolutely necessary to avoid a collision with the grippers 13 in order to prevent the products 1 from rolling out in the region of the fold edge detected by the grippers 13.
• multilayered folding products have certain folds in the folding area, which would be rolled out in the event of the rubber cylinder 4 running too little in relation to the impression cylinder 5.
• the provided wake ensures an undisturbed escape of the air stripped from the products 1.
• the caster angle depends on the product thickness, which means that a weaker caster is required for weaker products than for thicker products.
• the caster angle can be selected so that a caster of the rear edge of the cylinder groove 7 of the rubber cylinder 7 in the direction of rotation
• the rubber cylinder 4 is reset by the angle N while maintaining its relation to the plate cylinder 3 with respect to the impression cylinder 5. This can take place in the state or during operation.
• the rubber blanket 12 received on the rubber cylinder 4 can correspond to a normal rubber blanket.
• the effective area of the rubber blanket 12 is limited to the printing area.
• the rubber blanket 12 consists of a carrier film which has a rubber sticker 12a indicated in the indentation area by a dashed line. With this measure, the risk of lubrication can be further reduced. In addition, this has an advantageous effect on the control of the ink and dampening solution supply.
• the width of the inking unit 14 and the dampening unit 15 is also reduced to the impression area. It would be conceivable to do this by simply reducing the ink and dampening units that are correspondingly narrower over the entire length of the cylinder.
• REPLACEMENT LEAF and dampening systems In the exemplary embodiment shown, this is simply achieved by lateral stripping devices in the form of stripping knives which can be adjusted to a dyeing or dampening agent transfer cylinder. This has the advantage that "continu dyeing and dampening units can be used over the entire length of the cylinder.
• an automatic plate changing device 31 which is assigned to the plate cylinder 3 and is provided with cassettes 32 for the plates that are used or used one after the other, is provided in the exemplary embodiment shown.
• two impression mechanisms could be provided, one of which is activated and the other is passivated for the plate change.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Rotary Presses (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=6394753

Family Applications (1)

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Citations (3)

Family Cites Families (3)

• 1989
  • 1989-12-04 DE DE19893940019 patent/DE3940019A1/de active Granted
• 1990
  • 1990-12-03 JP JP50005790A patent/JPH04503781A/ja active Pending
  • 1990-12-03 EP EP19900917491 patent/EP0455782A1/de not_active Withdrawn
  • 1990-12-03 WO PCT/DE1990/000933 patent/WO1991008109A1/de not_active Application Discontinuation

Patent Citations (3)

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