DE19753091A1 - Sheet guiding device 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. After 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 a slope in the wall ordered 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 the jacket surface of the printing cylinder is adapted. 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.

EP 0 695 715 B1 describes a sheet smoothing device for guiding sheet-shaped substrates in a delivery of a rotary printing press known, which is used to unroll the substrates and in a guide is integrated. In relation to the guideway of the guide device is the arch smoothing device slightly reset from their level and serves Unrolling of sheets with one-sided printed sheet-shaped substrates. A Guide element for covering the sheet smoothing device with printed on both sides Media is in the space between the sheet smoothing device and Movable guideway so that a substantially closed guide path is formed.

An uneven contact of the printing material on the printing cylinder or lower blanket cylinder can not be excluded, especially in Area of the trailing 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 sub claims.

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 in the conveying direction of the printing fabrics one, e.g. B. effective on the principle of trailing edge application 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 Printing material in front of the blanket cylinder (for printing units) or form cylinder (for coating units) and sheet guiding cylinder, 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. B. the impression cylinder Inlet gap is formed for the substrate, which in the conveying direction Pressure gap has a tapered course. The bow Guide 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 guide device (facing away from the pressure gap), 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 Substrates with the top unprinted, d. H. no color and / or Has paint coverage. In addition, the invention is preferably such formed that the sheet smoothing device can be covered, d. H. 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 training, in addition to that in front of the pressure gap in the conveying direction  arranged sheet guiding device (with sheet smoothing device) another Sheet guiding device (without sheet smoothing device) after the printing nip arranged. This sheet guide device is used to guide the Substrate when leaving the printing nip. According to the pressure gap orderly sheet guiding device can also be pneumatically loaded, so that the blowing air emerging from the openings by means of pressure energy on the Printing material works.

The sheet guiding device has at least one pneumatically actuated beatable chamber with openings on the substrate for the Blow air outlet on. In a further development, the sheet guiding device has several chambers, which are separated by partitions and separate with Pneumatic systems for the blown air supply are coupled. Alternative is too training with a pneumatic system with only one blown air supply executable, the blown air supply up to that adjacent to the pressure gap Chamber is enough and the blowing air through openings in the bulkheads in the flows back into other chambers.

Between the underside (guide surface) of the sheet guiding device and the A lateral gap of the sheet guiding cylinder is formed, which a widening gap starting from the pressure gap in the conveying direction having.

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

Fig. 1 is a sheet-fed rotary printing machine with a turning system,

Fig. 2 is a sheet-guiding device with a decurler prior to the printing slot,

Fig. 3 shows a further embodiment of a sheet guide device,

Fig. 4 shows a sheet guiding device with blowing suction nozzles.

A sheet-fed rotary printing machine is shown in FIG. 1 in a row construction. Several printing units 1 are arranged in series with printing cylinders 10 and connected to one another by means of transfer drums 4 or turning systems 3 . Transfer drums 4 and turning systems 3 have assigned sheet guiding devices 7 . The last printing unit 1 is followed by a delivery arm 2 , which transports the printing material by means of sprocket shaft 5 and rotating chain systems 6 in the conveying direction 8 along the sheet guiding devices 7 and stores them on a delivery stack. Each printing unit 1 consists in a known manner of a printing cylinder 10 , a blanket cylinder 11 and a plate cylinder. An inking unit, possibly a dampening unit, is assigned to the plate cylinder, which will not be discussed further here.

In the case of sheet-fed rotary printing presses in series, it is known that one or more coating units can also be assigned to the printing units for inline finishing. A coating unit is comparable to a printing unit 1 . The blanket cylinder 11 of the printing unit then, as is known, corresponds to the forme cylinder of the coating unit, which is functionally connected to an application roller and a coating system. The printing cylinder 10 also takes over the function of the sheet guiding cylinder in the coating unit.

Blanket cylinders or forme cylinders 11 and impression cylinders 10 form a printing gap 12 through which the sheet-like printing material is transported and printed or varnished in the printing on position. Alternatively, in print from - position z. B. when checking the paper flow or if a printing unit or coating unit 1 is not required, the substrate lying on the outer surface of the printing cylinder 10 contactless to the blanket cylinder / forme cylinder 11 pass through the printing nip 12 by a sheet guiding device 9 remains in operation.

In the conveying direction 8 , this sheet guide device 9 is arranged in a first embodiment in front of the printing nip 12 . The sheet guiding device 9 has an approximately wedge-shaped cross section, which extends in a box-like manner over the width of the printing cylinder 10 and protrudes in the direction of the gusset-shaped space of the printing nip 12 , formed by the blanket / form cylinder 11 and printing cylinder 10 . Referring to FIG. 2, the sheet guide means is divided into three chambers 13, 14, 15 9, the chamber 13 is most visible in the nip 12 and the chamber 15 furthest from the pressure at the gap 12 is removed. The chambers 13 and 14 are each coupled to one or a common pneumatic system for the blown air supply and have openings 16 on a guide surface 22 (underside of the sheet guiding device 9 ) which are inclined counter to the conveying direction 8 to the adjacent pressure cylinder 10 . In addition, the chamber 13 preferably has at least one opening 16 which is directed towards the blanket / form cylinder 11 in the direction of the pressure gap 12 , such that the blown air flow blows against the blanket / form cylinder 11 in front of the pressure gap 12 and on the blanket / form cylinder 11 deflected and directed against the conveying direction 8 , the printing material on the jacket of the printing cylinder 10 leads and smoothes out. The chamber 15 of the sheet guiding device 9 which is the most distant from the printing nip 12 has a sheet smoothing device 17 which is assigned to the printing cylinder 10 and is coupled to a separate pneumatic system 18 . The pneumatic system 18 can be switched over either for the supply of blown air for sheet guiding or with suction air as the sheet smoothing device. Alternatively, the pneumatic system 18 can also be designed exclusively for the suction air supply to the sheet smoothing device 17 .

The sheet guiding device 9 is supported on both sides in side frames. The storage is preferably a swivel 21 , so that the sheet guiding device 9 is pivotable at a defined angle about this axis of rotation. So that the sheet guide device 9 , z. B. depending on the basis weight of the substrates to be processed or on the print subject, adjustable in their distance from the printing cylinder 10 . 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 or unequal to P ₂ based on the ambient pressure P ₀ . However, P ₁ <P ₂ <P ₀ is preferred.

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, preferably P ₁ <P ₂ <P ₃ <P ₀ .

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, according to 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 in the conveying direction 8 of a feed system as a feeding device, for. B. a suction belt table and system, arranged downstream and in front of the pressure gap 12 of the system printing unit.

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

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 . Gem. Fig. 4, the sheet guide device 9, farthest from the printing nip 12 is removed, in the guide surface 22 a plurality of which is arranged in series and connected with a pneumatic system 18 blowing suction nozzles 25 which are arranged below one another at defined intervals and extend at least over the minimum format width. The blowing-suction nozzles 25 are obliquely and directed counter to the conveying direction 8 of the printing material tangential to the guide surface 22 in order to generate a negative pressure between the substrate's surface and guide surface 22nd 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 guiding device 9 can also be implemented 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.

In a preferred embodiment, the sheet guiding device 9 arranged in front of the printing nip 12 is followed by a further sheet guiding device, following the printing nip 12 (in the conveying direction 8 ). The sheet guiding device serves to guide the printing material when leaving the printing nip 12 in the conveying direction 8. The downstream sheet guiding device can also be pneumatically acted upon for guiding the printing material on the printing cylinder 10 by means of blown air and has a guide surface which, with the lateral surface of the printing cylinder 10, differs from the printing nip 12 in the 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 lower side 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. Upon passing the sheet guide device 9, the Bogenglätteinrichtung 17 sucks the printing material in the polishing nip, the printing material is drawn briefly on the undulating contour, while the printing material extends counter to the conveying direction 8, and at the same time the printing material is unrolled (Decurleffekt). The blowing air flowing out of the openings 16 of the chambers 13 , 14 arranged in the guide surface 22 then immediately presses the printing material onto the printing cylinder 10. In the sheet guiding device 9 with the guide plate 20 , the printing material is stretched and unrolled on the guide plate 20 until shortly 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.

Reference list

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
P ₃

Pressure energy
P ₀

Ambient pressure
P _u

vacuum

Claims (16)

1. Sheet guiding device in a printing press, which is arranged in the conveying direction of a printing material in the gusset space in front of a printing gap formed by the forme cylinder and sheet guiding cylinder, axially parallel to a sheet guiding cylinder, characterized in that

• - That the sheet guiding device ( 9 ) from a with a pneumatic system ( 18 ) coupled for the air supply sheet smoothing device ( 17 ) and in the conveying direction ( 8 ) of the printing material the printing nip ( 12 ) upstream guide surface ( 22 ), and
• - That the sheet smoothing device ( 17 ) is integrated in the guide surface ( 22 ) to stretch and unroll the printing material against the conveying direction ( 8 ).

2. Sheet guiding device according to claim 1, characterized in that the guide surface ( 22 ) with the adjacent sheet guiding cylinder ( 10 ) forms an inlet gap ( 19 ) for the printing material, which is tapered in the conveying direction ( 8 ) of the printing material to the printing gap ( 12 ) . 3. Sheet guiding device according to claim 1 and 2, characterized in that the guide surface ( 22 ) is a guide plate ( 20 ) which is firmly connected to the sheet smoothing device ( 17 ). 4. Sheet guiding device according to claim 1 and 2, characterized in that the guide surface ( 22 ) has a plurality of obliquely arranged, directed against the conveying direction ( 8 ) of the printing material openings ( 16 ) for the blown air outlet and with at least one pneumatically actuated chamber ( 13 , 14 ) is in functional connection. 5. Sheet guiding device according to claim 1, 2 and 4, characterized in that the device ( 9 ) consists of several pneumatically actuated chambers ( 13 , 14 ) with openings ( 16 ) for the blown air outlet, which in the conveying direction ( 8 ) of the printing material before Printing gap ( 12 ) have the same or different printing energies (P ₁ , P ₂ ) acting on the printing material. 6. Sheet guiding device according to claim 1 and 2, characterized in that the sheet smoothing device ( 17 ) has at least one smoothing gap, wherein the smoothing gap can be closed within the guide surface ( 22 ) when the pneumatic system is switched off. 7. Sheet guiding device according to claim 1 and 2, characterized in that the pneumatic system coupled to the sheet smoothing device ( 17 ) can be switched over to a blown air supply in order to direct a blown air flow onto the adjacent lateral surface of the sheet guiding cylinder. 8. Sheet guiding device according to claim 1, characterized in that the device ( 9 ) is assigned to the printing nip ( 12 ) in a printing unit or coating unit ( 1 ) which is arranged downstream of a turning system ( 3 ) in the conveying direction ( 8 ). 9. Sheet guiding device according to claim 1, characterized in that the device ( 9 ) is assigned to the printing nip ( 12 ) in a printing unit or coating unit ( 1 ) which is arranged downstream of an application system in the conveying direction ( 8 ). 10. Sheet guiding device according to claim 1 or 11, characterized in that after the pressure gap ( 12 ) an at least one pneumatically actuated chamber with a guide surface having sheet guiding device is arranged, the openings for the blowing air outlet of the conveying direction ( 8 ) against the sheet guide cylinder ( 10 ) are directed. 11. Sheet guiding device in a printing press, which is arranged in the conveying direction of a printing material in the gusset space in front of a printing gap formed by the forme cylinder and sheet guiding cylinder, axially parallel to a sheet guiding cylinder, characterized in that

• - That the sheet guiding device ( 9 ) consists of a plurality of blowing-suction nozzles ( 25 ) which are functionally connected to a pneumatic system ( 18 ) for the air supply and a guiding surface ( 22 ) upstream of the printing nip ( 12 ) in the conveying direction ( 8 ) of the printing material. exists, and
• - that the blowing suction nozzles (25) inclined against the conveying direction (8) and are directed tangentially to the guide surface (22), to pull the material to be printed against the guide surface (22) and extend against the conveying direction (8).

12. Sheet guiding device according to claim 11, characterized in that the pneumatic system ( 18 ) with a line system ( 23 ) and a chamber ( 26 ) is connected, from which the compressed air flow to each blow-suction nozzle ( 25 ) can be divided. 13. Sheet guiding device according to claim 11, characterized in that the pneumatic system ( 18 ) is functionally connected to a chamber ( 15 ), from which the compressed air flow to each blowing / suction nozzle ( 25 ) can be divided. 14. Sheet guiding device according to claim 11 and 12 or 13, characterized in that each blowing-suction nozzle ( 25 ) is assigned an insert element ( 24 ) which is arranged in alignment with the guide surface ( 22 ). 15. Sheet guiding device according to claim 11, characterized in that the guide surface ( 22 ) is a guide plate ( 20 ) which is fixedly connected to the blowing-suction nozzles ( 25 ). 16. Sheet guiding device according to claim 11, characterized in that the guide surface ( 22 ) has a plurality of obliquely arranged, directed against the conveying direction ( 8 ) of the printing material openings ( 16 ) for the blown air outlet and with at least one pneumatically actuated chamber ( 13 , 14th ) is in functional connection.