EP1551634A1

EP1551634A1 - Drier for a web of material

Info

Publication number: EP1551634A1
Application number: EP03808666A
Authority: EP
Inventors: Georg Schneider; Wolfgang Otto Reder; Karl Erich Albert Schaschek
Original assignee: Koenig and Bauer AG
Current assignee: Koenig and Bauer AG
Priority date: 2002-10-16
Filing date: 2003-07-09
Publication date: 2005-07-13
Also published as: WO2004035313A1; AU2003250304A1; DE10248249B4; US7316184B2; DE10248249A1; US20060021245A1

Abstract

The invention relates to a drier for drying a web of material (07), comprising a passage duct (08) for the web of material. Drying takes place inside said passage duct (08) which is provided with at least one straight section. Said drier is disposed on a printing group (21) having vertical web guidance while the passage duct thereof comprises at least one straight section which horizontally directs a web of material delivered by the printing group. The passage duct encompasses at least two (36, 37) sections through which the web of material runs in opposite directions.

Description

description

Dryer for a web of material

The present invention relates to dryers for a material web according to the preamble of claim 1 or 2.

If such a paper web is processed in a folder immediately after printing, without the printing ink having time to dry, there is a risk of ink blurring in contact with the rollers of the folder or due to contact between several in the folder processed material webs is transferred from one web to another. Modern printing presses reach such high web speeds that the time between printing on a web section and its arrival at the folder measures only a fraction of a second. Sufficient drying of the ink is not possible during this period if it is not accelerated by technical aids.

Drying devices for drying a freshly printed material web are e.g. B. from DE 41 33 555 A1 or DE 4429891 A1.

DE 41 33 555 A1 describes an intaglio printing machine with several printing rollers for multi-color printing, in which a material web, after passing through each individual printing roller, passes through a transport path deflected on several rollers, on which drying devices are arranged. The course of the transport path is chosen so that the first deflection rollers, which pass the material web after passing through a printing nip, touch the unprinted rear side of the web. Only when the web has passed the drying facilities and there is no longer any risk of ink smearing due to contact with a deflection roller, do deflection rollers follow, which also touch the printed surface of the web. The construction known from DE 41 33 555 A1 cannot be used in printing machines for double-sided printing, since contact of the freshly printed web with a deflecting roller or any other surface should be avoided as long as the printing ink has not dried completely.

DE 4429 891 A1 therefore uses an elongated drying oven for drying a web printed on the front and back, through which the web runs in a straight line. It would be desirable per se to be able to guide the web vertically upwards through the drying oven in the same direction in which it emerges from the printing unit, so as to avoid the web, which has not yet completely dried, coming into contact with a deflection roller. However, such an arrangement would reach a height of many meters. Such a machine would therefore be difficult to accommodate in a hall. In order to avoid this and to be able to install the drying oven horizontally, a deflection roller between the outlet of the printing unit and the entrance of the drying oven is accepted. The arrangement described in the cited document with a horizontally oriented drying oven does not require extreme hall heights for its accommodation, but it does require a considerable amount of floor space, since a length of the drying oven of several meters is required in order to allow the printed material web to dwell sufficiently in order to dry the ink To reach the drying oven. Part of this area can be used to accommodate roll changers for the printing unit below the drying oven; in order to reduce the space requirement of such a printing system, it is nevertheless necessary to be able to reduce the length of the drying oven. The higher the web speeds in the printing system, the greater this requirement. In order to guarantee adequate drying as the web speed increases, the length of the oven must be increased in proportion to the web speed in the known construction.

DE 298 19 202 U1 discloses a dryer in which a material web over blown turning stations is deflected.

DE 10044676 A1 and DE 4033 642 A1 show devices for deflecting a material web by means of compressed air.

The invention has for its object to provide dryers for a material web.

The object is achieved by the features of claim 1 or 2.

The advantages that can be achieved with the invention are, in particular, that the dryer can be built very compactly and does not have or require deflection rollers that come into contact with the material web before it is completely dried. This is achieved by using curved deflection surfaces provided with air outlet openings on the through-channel of the dryer instead of deflection rollers. By creating an air cushion between the deflection surfaces and the material web wrapping around them through air emerging from the openings, extremely low-friction guidance of the material web is made possible and contact of the material web with a surface that could lead to blurring of colors is prevented. In order to produce a uniform air cushion between the deflecting surface and the material web, it is desirable for the deflecting surface to have a radius of curvature which is variable in the web running direction, which is minimal at an apex line of the deflecting surface and increases in each case towards the edges of the deflecting surface. Such a deflection surface can in particular have a hyperbolic cross section (in particular at a deflection angle of 90 °) or a semi-elliptical cross section.

Air outlet openings are preferably arranged along the apex line of the deflection surface.

A material web to be dried can be dried with the aid of a plurality of such deflection surfaces can be guided in a compact volume over a long length, so that long dwell times in the dryer can be achieved even at high web speeds. In order to intensify the drying effect, the dryer preferably has heat sources arranged on the through-channel, e.g. B. in the form of heat radiators.

The drying effect can also be intensified by air movement, which is why air outlet nozzles which are aligned with the material web are expediently provided on the at least one rectilinear section of the through-channel. These air outlet nozzles can advantageously be assigned a heating device in a supply line for the nozzles, for heating the air exiting through them. The heating device can in particular be a burner.

In the case of a dryer, in the passage of which a plurality of sections provided with air outlet nozzles are present, a heater is preferably provided in the supply line of the nozzles of at least one section located upstream in the direction of travel of the material web, while in the supply line of the nozzles at least one section is located downstream in the direction of travel of the material web located section such a heater is missing. While the material web is thus heated in the upstream section and thus drying is intensified, the downstream section enables the material web to cool rapidly.

To drive the airflow through the nozzles, a pressure pump can be arranged on a supply line of the nozzles; instead of or in addition, it is also conceivable to provide a suction pump for generating a negative pressure in the through-channel. Such a vacuum facilitates drying by lowering the boiling temperature of the color components to be evaporated; it can also serve to drive airflow through the nozzles. In order to achieve a long web length with a compact design, the through-channel preferably has at least two sections through which the material web runs in opposite directions. A first section preferably runs from an inlet of the dryer over a first distance in a first direction and a section adjoining it via a deflection surface runs over a second distance that is greater than the first in the opposite direction. The dryer thus extends from the entrance in two opposite directions, which simplifies the assembly of the dryer on a printing unit, even if the dryer protrudes beyond the printing unit in said direction or in the opposite direction.

Exemplary embodiments of the invention are shown in the drawings and are described in more detail below.

Show it:

1 and 2 are schematic sections through a deflection surface for contactless deflection of a material web;

3 shows a basic diagram of a dryer;

4 to 7 each form of dryer mounted on a printing unit according to the invention.

Fig. 1 shows a schematic section through a deflection surface 01, hereinafter also referred to as air saddle 01, for deflecting a material web 07, z. B. paper web 07 at an angle of 180 °. The air saddle 01 has a housing 02 that extends in the transverse direction of the material web 07 (the direction perpendicular to the plane of the drawing) an ellipse halved along its short diameter. The housing 02 can, for. B. consist of a steel sheet, a rigid plastic plate or the like. The cross section of the housing 02 is symmetrical with respect to a plane A, which intersects the housing 02 along an apex line 03. Along the apex line 03, the housing 02 is provided with a plurality of air outlet openings 04, which communicate with a compressed air channel 06, which extends inside the housing 02 in the longitudinal direction thereof. Compressed air emerging from the air outlet openings 04 is distributed between the housing 02 and a material web 07 wrapped around the housing 02 and thus forms an air cushion which keeps the material web 07 spaced from the surface of the housing 02. The overpressure between the housing 02 and the material web 07 required to maintain an air cushion with a thickness of typically 0.3 to 0.5 mm is a function of the tension of the material web 07. Pressure sensors on the surface of the material web 07 wrapped around it can therefore be used Housing 02 or also in the compressed air duct 06 can be provided, on the basis of whose measured values the web tension can be controlled and, if the detected pressure indicates a web break or other error, an emergency stop of a machine which contains the deflection surface can be initiated.

FIG. 2 shows a section analogous to that of FIG. 1 through an air saddle 01 with a 90 ° deflection angle. The principle of operation is the same as for the air saddle 01 from FIG. 1; Air emerging through the compressed air channel 06 and along an apex line 03 of the housing 02 air outlet openings 04 is distributed between the surface of the housing 02 and a material web 07 wrapping around it and thus produces an air cushion that enables an essentially frictionless conveyance of the material web 07.

1 and 2, a half-air saddle could also have an asymmetrical cross section. In such a case, the apex line 03 of the housing 02 is defined as that line on the surface of the housing 02 which touches an imaginary plane which, based on the sum F _{Σ of} the tensile force vectors F _v acting on the material web 07 in front of and behind the deflection surface 01; F _{R is} vertical. This arrangement minimizes the air throughput of the deflection surface required to build up an air cushion.

Fig. 3 shows a schematic of an air saddle 11; 12; 13 equipped according to FIGS. 1 and 2 dryer. A material web 07 to be dried is on a peripheral surface 11, for. B. an air saddle 11, for. B. an input air saddle 11 deflected by 90 °, extends straight through a through channel 08, z. B. a gap 08, between two plates 14 provided with air outlet nozzles, wraps around a peripheral surface 12, z. B. an air saddle 12, for. B. a 180 ° air saddle 12, runs through a second gap 08 to a peripheral surface 13, z. B. air saddle 13, z. B. an output air saddle 13, and from there leaves the dryer in the horizontal direction. The plates 14 provided with air outlet nozzles each delimit chambers 16 which, like the compressed air channels 06 of the air saddles 11; 12; 13 are connected to a pressure pump. In Fig. 3, two pressure pumps 17; 18 shown, one of which is the air saddles 11; 12; 13 and the other supplies the chambers 16. The air saddles 11; 12; 13 must namely be supplied with a higher pressure than the chambers 16. In principle, it would of course also be possible to use air saddles 11; 12; 13 and chambers 16 to be supplied via a common pressure pump and flow resistances from the pressure pump to the air saddles 11; 12; 13 or the chambers 16 to use supply lines to supply the former with a higher overpressure than the latter.

FIG. 4 shows a first exemplary embodiment of a dryer 22 mounted on a printing unit 21. A through-channel for printed material web 07 coming vertically from below from the printing unit 21 comprises an air saddle 11, e.g. B. a 90 ° air saddle 11 and a horizontally oriented gap 08 between plates provided with air outlet nozzles 14. The plates 14 form a housing which is essentially sealed except for the nozzles and an inlet and outlet slot for the material web 07, to which a suction pump 26 is connected in order to generate a negative pressure in the gap 08. The negative pressure causes fresh air to flow into the gap 08 via supply lines 27, which here are formed by spaces between the plates 14 and an outer housing 28 of the dryer 22. In the embodiment considered here, fresh air essentially flows in via an outlet 24 of the dryer 22, from which the material web 07 is led out. The fresh air can be preheated by a heating device (not shown in FIG. 4). The material web 07 emerging from the outlet 24 loops around a cooling roller 29 and finally reaches a folder 31.

A further developed embodiment is shown in FIG. 5. The printing unit 21 is the same as in the embodiment of FIG. 4. It comprises two assemblies 32, 33, each of which contains plate cylinders printing on the same side of the material web 07, and which can be moved apart in a frame 34 in order to gain access to the To enable plate cylinders.

The housing 28 of the dryer 22 extends over the entire width of the frame 34. The entrance 23 for the material web 07 is located approximately in the center on the underside of the housing 28. A 90 ° air saddle 11 arranged on it directs the material web coming from the printing unit 21 07 into a first horizontal rectilinear section 36 of the through-channel of the dryer 22, which extends from the entrance 23 in a direction leading away from the folder 31. The section 36 merges at a 180 ° air saddle 12 into a second horizontal rectilinear section 37, which leads the material web 07 in the opposite direction to an exit 24 adjacent to the folder 31. From there, the material web 07 runs over a cooling roller 29 to the folder 31.

With respect to a plane 43 defined by the vertically running material web 07, the first section 36 is arranged only on one side of the plane 43, the second Section 37 is located on both sides of level 43. The second section 37 is at least twice as long as the first section 36.

Sections 36; 37 of the through-channel 08 are each delimited here by baffles 38 which lead a fresh air stream penetrating at the outlet 24 into the housing 28 of the dryer 22 and driven by a pump (not shown) close to the material web 07. The fresh air stream, which in turn can be preheated, sweeps along the material web 07 at high speed and thus ensures effective drying. In the embodiment shown here, there is an air outlet 42 on the front side of the housing 28 opposite the outlet 24, and the lower of the two guide plates 38, which delimit the section 37, is interrupted at the level of the inlet 23, so that the air flow is divided and part of it can reach the air outlet 42 along the first section 36. Of course, it would also be possible to provide the air outlet 42 at the inlet 23 for the material web 07 in order to force the air flow to flow through the through-channel 08 over its entire length.

In a variant of this embodiment, the air is supplied to the straight sections 36; 37 as in the embodiment of FIG. 4 via chambers 39 separated from the through-channel by the guide plates 38 and nozzles formed in the guide plates 38.

The embodiment of FIG. 6 differs from that of FIG. 5 in that in the first section 36 of the through-channel 08 and in the half of the second section 37 which is remote from the folder 31, the guide plates 38 by arrangements of heat radiators 41, for. B. are replaced by electrically operated heating elements. A pump (not shown) drives a fresh air stream which flows through the housing 28 of the dryer 22 from the outlet 24 to an air outlet 42 formed on an opposite end face of the housing 28. The incoming fresh air does not need to be preheated in this embodiment, on the contrary, it is used in the right half of section 37 to cool the material web 07 in countercurrent, so that a cooling roller 29 between the dryer 22 and the folder 31 can be dispensed with.

A configuration for high drying performance is shown in FIG. 7. In this embodiment, as already shown in FIG. 3, the sections of the passage channel 08, here designated 36.1 to 36.5, are surrounded by chambers 16.1 to 16.5, the wall plates of which facing the passage channel 08 are provided with air outlet nozzles. A total of five sections are provided, the chambers 16.1; 16.2; 16.3 of the three sections 36.1 located upstream in the dryer 22 in relation to the transport direction of the material web 07; 36.2; 36.3 are supplied with hot gases from a burner and the chambers 16.4; 16.5 of the downstream sections 36.4; 36.5 are supplied with unheated fresh air in order to pre-cool the material web 07 before reaching a group of cooling rollers 29. The performance of such a dryer 22 is sufficient for heatset drying.

The fact that the dryer 22 can be mounted on a printing unit 21 without increasing its space requirement or the required distance from other machines predestines the dryer 22 especially for retrofitting already installed newspaper printing presses. This creates the possibility of printing on such machines even higher-quality papers with a lower absorbency than conventional newsprint, in particular papers with a coated surface. The field of application of such printing machines is expanded so that they can also be used at times of the day when no newspapers are to be printed. The cost-effectiveness of such a printing press can be increased considerably.

LIST OF REFERENCE NUMBERS

01 deflection surface, air saddle

02 housing

03 apex line

04 Air outlet opening

05 -

06 compressed air duct

07 Material web, paper web

08 pressure channel, gap

09 -

10 -

11 Deflection surface, air saddle, inlet air saddle, 90 ° air saddleI

12 deflection surface, air saddle, 180 ° air saddle

13 deflection surface, air saddle, outlet air saddle

14 plates

15 -

16 combs

17 pressure pump

18 pressure pump

19 -

20 -

21 printing unit

22 dryer

23 entrance

24 output

25 -

26 suction pump

27 supply line 28 housing, outer

29 chill roll

30 -

31 folder

32 assembly (21)

33 assembly (21)

34 frames

35 -

36 section, rectilinear, first

37 section, rectilinear, second

38 baffle

39 chamber

40 -

41 radiant heaters

42 air outlet

43 level

A level

F _Σ sum

F _v traction vector

F _R traction vector

36.1 section

36.2 section

36.3 section

36.4 section

36.5 section 16.1 chamber

16.2 Chamber

16.3 Chamber

16.4 Chamber

16.5 chamber

Claims

Expectations

1. dryer for drying a material web (07) with a through channel (08) for the material web (07), in which the drying takes place and which has at least one rectilinear section (36; 37), the dryer on a printing unit (21) is arranged with a vertical web guide and its through channel (08) has at least one rectilinear section (36; 37) guiding horizontally from the printing unit (21) fed material web (07), characterized in that the through channel (08) has at least two from the web (07) has sections (36; 37) running in opposite directions.

2. Dryer for drying a material web (07), with a through channel (08) for the material web (07), in which the drying takes place and which has at least one rectilinear section (36; 37), the dryer on a printing unit (21 ) is arranged with a vertical web guide and that its through channel (08) has at least one straight section (36; 37) horizontally leading from the printing unit (21) fed material web (07), characterized in that the through channel (08) has a plurality of having sections (36; 37) provided with air outlet nozzles, a heating device being provided in the supply line of the nozzles of at least one section (36; 37) upstream in the running direction of the material web (07) and at least one in the supply line of the nozzles in the running direction of the material web (07) downstream section a heater is missing.

3. Dryer according to claim 1 or 2, characterized in that at an inlet (23) and / or an outlet (24) and / or between two sections (36; 37) of the through-channel traversed by the material web (07) in different directions (08) one wrapped by the material web (07), with Air outlet openings (04) provided curved deflection surface (01; 11; 12; 13) is arranged.

4. Dryer according to claim 3, characterized in that the deflecting surface (01) has a variable radius of curvature in the web running direction, which is minimal at an apex line (03) of the deflecting surface (01) and increases towards the edges of the deflecting surface.

5. Dryer according to claim 3, characterized in that the air outlet openings (04) are arranged along an apex line (03) of the deflection surface (01).

6. Dryer according to claim 1 or 2, characterized in that heat sources (41) are arranged on the through-channel (08).

7. Dryer according to claim 1, characterized in that on the at least one rectilinear section (36; 37) of the through-channel (08) on the material web (07) aligned air outlet nozzles are arranged.

8. Dryer according to claim 2 or 7, characterized in that a heating device is arranged in a supply line of the nozzles.

9. Dryer according to claim 2 or 8, characterized in that the heating device is a burner.

10. Dryer according to claim 1 or 7, characterized in that the through-channel (08) has a plurality of sections (36; 37) provided with air outlet nozzles, wherein in the supply line of the nozzles at least one section located upstream in the running direction of the material web (07) (36; 37) a heating device is provided and in the The supply line for the nozzles of at least one section located downstream in the direction of travel of the material web (07) lacks a heating device.

11. Dryer according to claim 7 to 10, characterized in that a pressure pump (16) is arranged on a supply line of the nozzles.

12. Dryer according to claim 1 or 2, characterized in that a suction pump (26) for generating a negative pressure is arranged in the through-channel (08).

13. Dryer according to claim 2, characterized in that the through-channel (08) has at least two sections (36; 37) which are passed through by the material web (07) in opposite directions.

14. Dryer according to claim 1 or 13, characterized in that a first section (36) extends from an inlet (23) of the dryer (22) over a first distance in a first direction and a section adjoining it via a deflection surface (12) (37) runs a second distance greater than the first, opposite to the first direction.

15. Dryer according to claim 1 or 13, characterized in that the second section (37) is at least twice as long as the first section (36).

16. Dryer according to claim 1 or 13, characterized in that a section (36) only on one side of a plane (43) defined by the vertically running material web (07) and the other section (37) on both sides of the plane (43 ) is arranged.