EP0922577B1 - Device for guiding sheets in a printing press - Google Patents

Abstract

The sheet guide device (9) is fitted axially parallel to the sheet guide cylinder in front of the printing gap in the sheet feed direction (8). The sheet guide device consists of a sheet smoothing device, connected to a pneumatic air supply, and a guide surface in front of the printing gap in the sheet feed direction. The sheet smoothing device is integrated into the guide surface to stretch out the sheet in the opposite to sheet feed direction.

Description

The invention relates to a sheet guiding device in a printing press according to the preamble of the main claim.

A sheetfed press for perfecting on the principle Rubber against rubber in a pressure zone is known from DE 26 03 483 A1. The sheet guide is designed such that in the conveying direction of the Printing material with a first blowing tube coupled to a compressor Openings is arranged, the blown air jet against the substrate Press drum and a contact of the substrate with the lower Blanket cylinder (sheet guiding cylinder) prevented in front of the printing nip. In front the pressure gap is also a suction box with a preferably concave curved suction surface arranged to suck the substrate serves. This means that the substrate should run along the suction surface for as long as possible be performed before the lower blanket cylinder in front of the printing nip Touch comes. The suction box is coupled to a vacuum source. To a second blow pipe, called an air sword, is arranged from the pressure gap whose openings blow air on the surface of the upper blanket cylinder as also flows into the pressure gap itself.

It is in the conveying direction of the substrate in front of the printing nip of Blanket cylinder and impression cylinder arranged further blowing device known by MAN Roland Druckmaschinen AG in the Roland series 800, a rotary printing press based on the five-cylinder principle, in the Years 1978 to 1995 was realized and sold. This blower is out a plurality of spaced from each other in the cylinder axis and the Curvature of the impression cylinder surface adapted guide elements formed, each guide element having a hollow cylindrical cross section having. Each guide element has obliquely arranged in the wall, against the impression cylinder and the conveying direction of the substrate directed air vents, which lift the sheet from the Avoid the pressure cylinder outer surface. The inside of the hollow cylindrical The blower air chamber represents the guide element with a pneumatic system for the blown air supply is coupled. The blowing air openings Wall of the guide elements represents an outer contour, that of the outer surface of the impression cylinder is adjusted. There are also additional smaller ones Blown air openings arranged, which - viewed transversely to the direction of movement - in Edge area of the guide elements are directed inwards and outwards.

From EP 0 695 715 B1 a sheet smoothing device for guiding sheet-shaped printing materials in a delivery of a rotary printing press is known, which serves to unroll the printing materials and is integrated in a guide device. With respect to the guideway of the guide device, the sheet smoothing device is slightly set back from its plane and is used for unrolling sheets in the case of sheet-type printing materials printed on one side. A guide element for covering the sheet smoothing device in the case of printing materials printed on both sides can be moved into the space between the sheet smoothing device and the guideway, so that an essentially closed guideway is formed.
An uneven contact of the printing material on the printing cylinder or lower blanket cylinder cannot be ruled out, particularly in the area of the rear edge of the sheet material.

The invention has for its object a sheet guiding device in to create a printing press that avoids the disadvantages mentioned, the in particular a more even guidance of the substrate on the Bow guide cylinder, in particular a printing cylinder, allowed and one guaranteed improved entry of the printing material into a printing nip.

The task is determined by the training characteristics of the main claim or Secondary claim solved. Further training results from the subclaims.

It has been found that in the printing process as well as in the painting process, in particular for substrates with a lower basis weight, the rear area of the sheet-shaped substrates tend to curl. This effect increases with increasing number of printing gaps or painting gaps within the Printing press. For printing presses that go from fine to fine and Reverse pressure or vice versa, this effect is particularly effective negative if the printing units / coating units are in the conveying direction of the printing materials one, e.g. effective according to the principle of trailing edges, Turning system are upstream and this turning system in turn printing units / Follow coating units in the conveying direction. The printing material can be rolled up lead to undesired register misalignment and duplication. A comparable one The effect can be seen with substrates that are already printed on one side or varnished from a turned feeder stack again the printing units / Coating units are fed with the unprinted side on top.

To ensure smooth, flutter-free guiding of the sheet-like substrate on the Realizing the lateral surface of the sheet guiding cylinder is in the conveying direction of the Substrate in front of the blanket cylinder (for printing units) or forme cylinder (for coating units) and sheet guiding cylinders, preferably the Pressure cylinder, formed a pressure gap according to the invention, arranged pneumatically actuated sheet guide device, the Underside as a guide surface is adjacent to the sheet guide cylinder.

The sheet guiding device is arranged in front of the printing nip in such a way that between the guide surface of the sheet guiding device and the Lateral surface of the sheet guiding cylinder, e.g. of the impression cylinder, a Inlet gap is formed for the substrate, which in the conveying direction Pressure gap has a tapered course. The sheet guiding device is arranged axially parallel to the sheet guide cylinder.

According to a first solution, the sheet guiding device has on the At least one, guiding surface showing the sheet-guiding cylinder At least over the minimum format width, sheet smoothing device. The sheet smoothing device is in the sheet guiding device, especially in its Guide surface, integrated and has at least one smoothing gap and is with a pneumatic system in functional connection. In the conveying direction of the The substrate is the sheet smoothing device at the beginning of the sheet guiding device (facing away from the printing nip), the other Part of the sheet guiding device at least as a guiding surface up close of the gusset-shaped pressure gap is sufficient.

The sheet guiding device according to the invention is particularly suitable for Printing materials, the top of which is unprinted, i.e. no color and / or Has paint coverage. In addition, the invention is preferably such formed that the sheet smoothing device can be covered, i.e. the cover is aligned with the guide surface, and thus the sheet guiding device is also Can be used as a guiding surface for substrates with a printed top.

According to a second solution, the sheet smoothing device in the Guide surface at least one row spaced apart and with a pneumatic system with functionally connected blowing and suction nozzles extend at least across the minimum format width. The blow-suction nozzles are inclined in the guide surface against the conveying direction of the substrate directed.

In a further embodiment, in addition to the sheet guiding device (with sheet smoothing device) arranged in front of the printing nip in the conveying direction, a further sheet guiding device (without sheet smoothing device) is arranged after the printing nip. This sheet guiding device serves to guide the printing material when leaving the printing nip. The sheet guiding device arranged downstream of the printing nip can also be acted upon pneumatically, so that the blown air emerging from the openings acts on the printing material by means of pressure energy.
In this case, the sheet guiding device has at least one pneumatically actuatable chamber with openings directed towards the printing material for the blowing air outlet. In one development, the sheet guiding device has a plurality of chambers which are separated by partitions and are separately coupled to pneumatic systems for the supply of blown air. Alternatively, the design can also be carried out with a pneumatic system with only one blown air supply, the blown air supply reaching as far as the chamber adjacent to the pressure gap and the blown air flowing back through openings in the partitions into the further chambers.
An outlet gap is formed between the underside (guide surface) of the sheet guiding device and the lateral surface of the sheet guiding cylinder and has an expanding gap starting from the printing gap in the conveying direction.

Fig. 1

eine Bogenrotationsdruckmaschine mit einem Wendesystem

Fig. 2

eine Bogenführungseinrichtung mit einem Bogenglätter vor dem Druckspalt

Fig. 3

eine weitere Ausbildung einer Bogenführungseinrichtung

Fig. 4

eine Bogenführungseinrichtung mit Blas-Sog-Düsen

The invention will be explained in more detail using an exemplary embodiment. The following schematically show:

Fig. 1

a sheet-fed rotary printing press with a perfecting system

Fig. 2

a sheet guiding device with a sheet smoother in front of the printing nip

Fig. 3

a further embodiment of a sheet guiding device

Fig. 4

a sheet guide device with blow-suction nozzles

A sheet-fed rotary printing press is shown in a row construction in accordance with FIG. 1. Several printing units 1 with printing cylinders 10 are strung together and with each other by means of transfer drums 4 or turning systems 3 connected. Transfer drums 4 and turning systems 3 have assigned Sheet guiding devices 7. The last printing unit 1 is a delivery arm 2 downstream, which the printing material by means of sprocket shaft 5 and revolving chain systems 6 in the conveying direction 8 on the sheet guiding devices 7 transported along and placed on a stack of cantilevers Printing unit 1 consists in a known manner of a printing cylinder 10, a Blanket cylinder 11 and a plate cylinder. The plate cylinder is a Inking unit, possibly assigned a dampening unit, which is not dealt with here shall be.

In sheet-fed rotary printing presses in series are for inline finishing as is well known, one or more coating units the printing units assignable. A coating unit is comparable to a printing unit 1. The Blanket cylinder 11 of the printing unit is known to correspond to that Forme cylinder of the coating unit, with an application roller and a coating system is in functional connection. The impression cylinder 10 also takes over the function of the sheet guiding cylinder in the coating unit.

Blanket cylinder or forme cylinder 11 and impression cylinder 10 form one Printing gap 12 due to the printing position of the sheet-shaped printing material transported and printed or varnished. Alternatively, in the print off position e.g. when checking the paper flow or if a printing unit or coating unit 1 is not is required, which rests on the outer surface of the printing cylinder 10 Printing material contactless to the parked blanket cylinder / form cylinder 11 pass the printing nip 12 by a sheet guiding device 9 in operation remains.

In the conveying direction 8, this sheet guiding device is in a first embodiment in front of the printing nip 12 9 arranged. The sheet guiding device 9 has one approximately wedge-shaped cross-section, which is box-shaped over the width of the Printing cylinder 10 extends and in the direction of the gusset-shaped space of the Printing nip 12 formed by the blanket / form cylinder 11 and Printing cylinder 10 protrudes. 2, the sheet guiding device 9 is in three chambers 13, 14, 15 divided, the chamber 13 farthest in the Pressure gap 12 protrudes and the chamber 15 furthest from the pressure gap 12 is. The chambers 13 and 14 are each with one or a common Pneumatic system for the blown air supply coupled and point at one Guide surface 22 (underside of sheet guiding device 9) openings 16 on, opposite to the conveying direction 8 to the adjacent printing cylinder 10 are inclined. The chamber 13 preferably also has at least one Opening 16, which in the direction of pressure gap 12 against the blanket / Forme cylinder 11 is directed such that the blown air flow in front of the pressure nip 12 blows against the blanket / form cylinder 11 and on the blanket / Forme cylinder 11 deflected and directed against the conveying direction 8 Printing material on the jacket of the printing cylinder 10 leads smoothly and spreads out. The most distant chamber 15 of the sheet guiding device 9 from the printing nip 12 has a sheet smoothing device assigned opposite the printing cylinder 10 17 and has a separate pneumatic system 18 coupled. The pneumatic system 18 is optionally for the supply of blown air switchable for sheet guidance or with suction air as sheet smoothing device. Alternatively, the pneumatic system 18 can also be used exclusively for the Suction air supply to the sheet smoothing device 17 may be formed.

The sheet guiding device 9 is supported on both sides in side frames. The bearing is preferably a swivel joint 21, so that the sheet guiding device 9 can be pivoted about this axis of rotation at a defined angle. The sheet guide device 9 can thus be adjusted in its distance from the printing cylinder 10, for example depending on the weight per unit area of the printing materials to be processed or on the printing subject. This distance represents an inlet gap 19 which, despite the pivotability of the sheet guiding device 9, is always arranged to taper in the direction of the printing gap 12. Blown air flows out of the chambers 13, 14 from the openings 16 arranged in the guide surface 22, their kinetic energy being converted into printing energies P ₁ , P ₂ which act on the printing material and are greater than the ambient pressure P ₀ . The pressure energy P _{1 is} assigned to the area of the chamber 13 and the pressure energy P _{2 is} assigned to the area of the chamber 14, the pressure energies P _{1 being} equal to or different from P ₂ based on the ambient pressure P ₀ . However, P ₁ > P ₂ > P ₀ preferably applies.

The sheet smoothing device 17 is integrated into the chamber 15 and has in its smoothing gap a suction bar running across the format width transverse to the conveying direction 8 of the printing material, which is formed by bores, slots or a continuous groove. The sheet smoothing device 17 has a wavy, curved contour and is assigned adjacent to the printing cylinder 10. The chamber 15 and the suction bar are provided with a vacuum P _u by the pneumatic system 18. P ₁ > P ₂ > P ₀ > P _u .

In a further development, the sheet smoothing device 17 can be closed with movable means, so that the smoothing gap is ineffective, the pneumatic system 18 is out of operation. The movable means close the smoothing gap in such a way that they are aligned with the guide surface 22.
In a further development, the sheet smoothing device 17 can be exposed by the closable means, the pneumatic system 18 is switched over to blowing air supply, so that blowing air flows out of the bores, slots or the groove of the smoothing gap in the direction of the sheet guiding cylinder, pressure cylinder 10. The sheet smoothing device 17 is thus a blowing device. The kinetic energy of the blown air flow from the area of the blower device (switched sheet smoothing device 17) acts as printing energy P ₃ on the printing material, P ₁ > P ₂ > P ₃ > P ₀ preferably being used.

In the first embodiment, the sheet guiding device 9 according to the invention is arranged in the conveying direction 8 within a sheet-fed rotary printing press in a row construction, after a turning system 3 and in front of the printing nip 12 of the subsequent printing unit (FIG. 1) or coating unit 1.
In a further development, the sheet guiding device 9 according to the invention is arranged in the conveying direction 8 within a sheet-fed rotary printing press in a row construction, as a feed system, for example a suction belt table and system, and arranged in front of the printing nip 12 of the system printing unit.

Alternatively, the sheet guiding device 9 consists of a simple design the sheet smoothing device 17 and a firmly connected guide plate 20. Die Sheet smoothing device 17 is in turn coupled to the pneumatic system and instead of the chambers 13, 14 described above is in the conveying direction 8 of Sheet smoothing device 17 following that projecting close to the printing nip 12 Baffle plate 20 arranged. The baffle plate 20 corresponds to the in this example Guide surface 22 and forms with the jacket of the pressure cylinder 10 Inlet gap 19.

In a second embodiment, the sheet guiding device 9 is again arranged in the conveying direction 8 in front of the printing nip 12 with an approximately wedge-shaped cross section, which extends in a box-like manner over the width of the printing cylinder 10 and projects in the direction of the printing nip 12. 4, the sheet guiding device 9, furthest away from the printing nip 12, in the guiding surface 22 has a plurality of blowing-suction nozzles 25 arranged in series and connected to a pneumatic system 18, which are arranged at defined distances from each other extend at least over the minimum format width. The blow-suction nozzles 25 are directed obliquely against the conveying direction 8 of the printing material and tangentially to the guide surface 22 in order to generate a negative pressure between the upper side of the printing material and the guide surface 22. In the area of the chamber 15, the compressed air is supplied from the pneumatic system 18 to a chamber 26 via a line system 23. From the chamber 26, the compressed air flow is divided into the individual blow-suction nozzles 25 that are functionally connected to the chamber 26. In a preferred embodiment, each blow-suction nozzle 25 is assigned an insert element 24, which is connected to the chamber 15 or the Line system 23 defines the flow cross-section for the respective blowing-suction nozzle 25. The insert elements 24 are arranged in total in alignment with the guide surface 22.
The sheet guiding device 9 with blowing-suction nozzles 25 in turn has the guiding surface 22 in the conveying direction 8, which is designed in a simple form as a guide plate 20 reaching close to the pressure gap 12. In addition, the sheet guide device 9 can also be designed with pneumatically actuated chambers 13, 14, 15. The chamber 13 projects furthest in the direction of the pressure gap 12 and the chamber 15 is furthest away from the pressure gap 12. The chamber 15 accommodates the line system 23 for the compressed air supply or is itself designed as a line system for the compressed air supply. In this embodiment, the chamber 15 is directly functionally connected to each blowing and suction nozzle 25. As already described, the chambers 13, 14 have the openings 16 integrated in the guide surface 22 for the blowing air outlet.

The sheet guiding device 9 arranged in front of the printing nip 12 is shown in FIG preferred training a further sheet guiding device, the printing nip 12 (in the direction of conveyance 8), downstream. The sheet guiding device is used to guide the substrate when leaving the printing nip 12 in Conveying direction 8. The downstream sheet guiding device is also can be pneumatically loaded to guide the substrate on the Printing cylinder 10 by means of blown air and has a guide surface which with the The lateral surface of the printing cylinder 10 extends from the printing gap 12 in Has conveying direction 8 widening outlet gap.

The operation of a printing press is as follows: the printing system 3 transfers the printing material in the transfer area to the downstream printing cylinder 10 and, with the unprinted upper side (the printed underside is guided on the printing cylinder 10), the printing nip 12 of the subsequent printing unit 1 in the conveying direction 8 fed. After leaving the transfer area in the conveying direction 8, the rear area of the sheet-like printing material tends to lift off the printing cylinder 10 and possibly to flutter. When passing the sheet guiding device 9, the sheet smoothing device 17 sucks the printing material into the smoothing gap, the printing material is briefly pulled over the wave-shaped contour, the printing material stretches in the direction opposite to the conveying direction 8 and at the same time the printing material is unrolled (decurling effect). The blowing air flowing out of the openings 16 in the guide surface 22 of the chambers 13, 14 then immediately presses the printing material onto the printing cylinder 10. In the sheet guiding device 9 with the guide plate 20, after the stretching and unrolling of the printing material, the latter is on the guide plate 20 until just before Pressure gap 12 out.
If the sheet guiding device 9 is equipped with blow-suction nozzles 25, the printing material is drawn against the guide surface 22 and the underside of the insert elements 24 by the negative pressure and stretched against the conveying direction 8. When formed with the guide plate 20, the printing material is guided there until shortly before the printing gap 12. In the case of formation with the chambers 13, 14, the printing material is in turn pressed onto the printing cylinder 10 by means of the blown air emerging from the openings 16 and its printing energies.

List of reference symbols

1

Printing unit

2nd

boom

3rd

Turning system

4th

Transfer drum

5

Sprocket shaft

6

Chain system

7

Sheet guiding device

8th

Direction of conveyance

9

Sheet guiding device

10th

Impression cylinder

11

Blanket cylinder / forme cylinder

12th

Pressure gap

13

chamber

14

chamber

15

chamber

16

opening

17th

Sheet smoothing device

18th

Pneumatic system

19th

Inlet gap

20th

Baffle

21

Swivel

22

Leadership area

23

Pipe system

24th

Insert element

25th

Blow-suction nozzle

26

chamber

P ₁

Pressure energy

P ₂

Pressure energy

P3

Pressure energy

P ₀

Ambient pressure

P _u

vacuum

Claims (16)

1. Sheet guiding device in a printing press which is arranged in the feed direction of a material to be printed in the spandrel shaped space in front of a printing slot formed from forme cylinder and sheet guiding cylinder axially parallel to a sheet guiding cylinder, characterised in that

   the sheet guiding device (9) consists of a sheet flattening device (17) linked for air supply with a pneumatic system (18) and a guide surface (22) arranged in the feed direction (8) of the printed material in front of the printing slot (12) and

   the sheet flattening device (17) is integrated into the guide surface (22) in order to stretch the material to be printed counter to the feed direction (8) and to unroll it.
2. Sheet guiding device according to Claim 1, characterised in that the guide surface (22) forms with the neighbouring sheet guiding cylinder (10) a running in slot (19) for the material to be printed which is arranged in the feed direction of the material to be printed getting smaller towards the printing slot (12).
3. Sheet guiding device according to Claim 1 and 2, characterised in that the guide surface (22) is a guide sheet (20) which is firmly connected with the sheet flattening unit (17).
4. Sheet guiding device according to Claim 1 and 2, characterised in that the guide surface (22) has a plurality of obliquely arranged openings (16) for blown air outlet directed counter to the feed direction (8) of the material to be printed and is functionally connected with at least one chamber (13, 14) which can be pneumatically subjected.
5. Sheet guiding device according to Claim 1, 2 and 4, characterised in that the device (9) has several pneumatically subjectable chambers (13, 14) with openings (16) for blown air emerging which have in the feed direction (8) of the material to be printed prior to the printing slot (12) the same or different pressure energies (P₁, P₂) acting on the material to be printed.
6. Sheet guiding device according to Claim 1 and 2, characterised in that the sheet flattening unit (17) has at least one flattening slot wherein the flattening slot with the pneumatic system switched off can be covered within the guide surface (22).
7. Sheet guiding device according to Claim 1 and 2, characterised in that pneumatic system linked with the sheet flattening unit (17) can be switched over to blown air supply in order to direct a stream of blown air on to the neighbouring cover surface of the sheet guiding cylinder.
8. Sheet guiding device according to Claim 1, characterised in that the device (9) is fitted to the printing slot (12) in a printing unit or varnishing unit (1) which is arranged downstream in the feed direction (8) of a turning system (3).
9. Sheet guiding device according to Claim 1, characterised in that the device (9) is fitted to the printing slot (12) in a printing unit or varnishing unit (1) which is arranged in the feed direction (8) downstream of a feeder system.
10. Sheet guiding device according to Claim 1 or 11, characterised in that after the printing slot (12), a sheet guiding device is arranged having at least one pneumatically subjectable chamber with a guide surface, the openings of which, for blown air exhaust, are directed counter to the feed direction (8) on to the sheet guiding cylinder (10).
11. Sheet guiding device in a printing press which, in the feed direction of a material to be printed is arranged in the spandrel shaped space in front of a printing slot formed by forme cylinder and sheet guiding cylinder axially parallel to a sheet guiding cylinder, characterised in that

    the sheet guiding device (9) consists of a plurality of blowing/sucking nozzles (25) functionally connected with a pneumatic system (18) for air supply and a guide surface (22) arranged in the feed direction (8) of material to be printed prior to the printing slot (12) and

    the blowing/sucking nozzles (25) are directed obliquely counter to the feed direction (8) and tangentially to the guide surface (22) in order to pull the material to be printed against the guide surface (22) and to stretch it counter to the feed direction (8).
12. Sheet guiding device according to Claim 11, characterised in that the pneumatic system (18) is connected with a lead system (23) and a chamber (26) from which the compressed airstream can be divided to each blowing/sucking nozzle (25).
13. Sheet guiding device according to Claim 11, characterised in that the pneumatic system (18) is functionally connected with a chamber (15) from which the compressed airflow can be divided to each blowing/sucking nozzle (25).
14. Sheet guiding device according to Claim 11 and 12 or 13, characterised in that each blowing/sucking nozzle (25) is fitted with an insert element (24) which is arranged flush relative to the guide surface (22).
15. Sheet guiding device according to Claim 11, characterised in that the guide surface (22) is a guide sheet (20) which is fixedly connected with the blowing/sucking nozzles (25).
16. Sheet guiding device according to Claim 11, characterised in that the guide surface (22) has a plurality of obliquely arranged openings for blown air exhaust directed counter to the feed direction (8) of the material to be printed and is functionally connected with at least one pneumatically subjectable chamber (13, 14).

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