DE102010006208A1 - Turn unit for use in printing machine for turning substrate web i.e. paper web for printing web, has propulsion unit rotating turn element with rotation speed to form air cushion between outer surface of turn element and substrate web - Google Patents

Abstract

The unit has a turn element (20) bent towards a web conveying direction, and a propulsion unit i.e. direct current motor, rotating the turn element. The propulsion unit is in a position to rotate the turn element with a rotation speed to form an air cushion between an outer surface (35) of the turn element and a substrate web i.e. print material web (6). An air cushion unit comprises a spiral groove structure in an outer surface. The turn element is designed as a hollow pipe with an inner space, and the air cushion unit has two fan wheels, which are arranged at opposite ends of the pipe. Independent claims are also included for the following: (1) a method for printing the substrate web (2) a method for turning the substrate web.

Description

The present invention relates to a method and a device for turning web-like substrates, in particular sheet-like substrates in a printing press, which are to be supplied to a perfecting after a perfect printing.

Turning units are known in printing technology, which use web-shaped substrates for a perfecting print with the help of crossed turning bars. Such a turning unit is for example in the DE 100 63 025 A1 described. The turning unit described therein has fixed hollow turning bars whose interior is supplied with blowing air, which exits from openings of the turning bars in a respective area in which the paper web wraps around the turning bar. As a result, the paper web should be performed floating over an air cushion. In this case, however, a large amount of blowing air is required, the generation and blowing of which leads to a significant energy and noise pollution.

Also from the DE 198 34 679 A1 Such a turning unit is described with hollow, fixed turning bars, wherein the turning bars has a profile which is to promote the construction of air cushions between the turning bar and a printing material web.

In order to produce a sufficient air cushion over the width of a substrate web in this embodiment, either a high speed of the printing material relative to the fixed turning bars or in turn a high amount of blast air with the associated disadvantages is necessary. In particular, if no or insufficient blowing air is used, the printing material is up to reaching the required web speed on the turning bar, which causes high friction and thereby high abrasion on the turning bar. It should be noted that due to the inertia of the components involved in transporting the web, it may take some time to reach the speed. In addition, it is possible that the required web speed may not be achieved for all processes and web materials, which in turn can result in high friction and thus also high abrasion on the turning bar.

The present invention has for its object to provide a device for turning a web-shaped substrate of the above type, which eliminates at least one of the above disadvantages, in particular a low friction between the substrate web, or substrate web and turning bar, or turning element achieved.

According to the invention, this object is achieved by a turning unit according to claim 1 and a method for turning a substrate web according to claim 11. Further embodiments of the invention will become apparent from the respective dependent claims.

In particular, a turning unit for a substrate web is provided, which has at least one turning element which is arranged angled to a web conveying direction. Furthermore, the turning unit has a drive for rotating the turning element, wherein the drive is able to rotate the turning element at a speed which causes the formation of an air cushion between a lateral surface of the turning element and a substrate web. By the rotation of the turning element on the one hand stiction between the turning element and the substrate web can be avoided and the friction can be substantially minimized by the formation of the air cushion. The turning bar can be accelerated much faster than the substrate web to the speed required to produce the air cushion as the substrate web itself. In particular, regardless of the web speed, it is possible to provide sufficient relative movement between substrate web and turner bar to form an air bag. The drive can be, for example, a DC motor, which represents a cost-effective drive form, since no special requirements for speed constancy or torque of the motor are provided.

The turning element may, for example, be arranged at a 45 ° angle to a first web conveying direction, wherein the web running direction of the substrate web prior to turning by the turning element is the first web conveying direction. This would result in a 90 ° turn across the first web conveying direction.

According to one embodiment, air cushioning means are provided on the turning element, which promote the formation of the air cushion between the lateral surface of the turning element and the substrate web upon rotation of the turning element. In this case, the air cushioning means can be formed by at least one groove structure, in particular a spiral groove structure in the lateral surface. Such a groove structure in the substrate guide surface enables an improved and more uniform distribution of air between the turning element and a substrate web guided over it. As a result, the energy required for the rotation of the turning element to produce a sufficient air cushion can be reduced. This can also result in a lower noise. In particular, in edge regions of the substrate web, the Slot structure provide a controlled flow of air, which may be a fluttering of the substrate web and an associated noise development can be reduced

According to a further embodiment, the turning element is a tube with an interior space, wherein the air cushioning means may comprise at least one fan, in particular a radial compressor, which is arranged in the interior of the tube and rotatable with the tube. In this embodiment, the turning element would continue to have gas outlet openings, which extend from the interior to the lateral surface of the turning element and by the air, which was sucked by the fan, or by the centrifugal compressor is discharged to promote the formation of the air cushion between substrate web and lateral surface yet. Such an arrangement requires no additional blower device for generating blow or compressed air and thus represents a cost-effective solution.

In another embodiment, the air cushioning means in the interior of the tube may have at least two fan wheels, which are arranged at opposite ends of the tube, whereby a higher dynamic pressure can be generated in the interior of the tube which may be accompanied by an improvement of the air cushion.

In order to achieve that a gas stream flowing out of the gas outlet openings reaches the region between the lateral surface of the turning element and the substrate web, at least one air guide plate can be arranged adjacent to the turning element. This can lead to an improvement of the air cushion, since without such an air guide plate air flowing from gas outlet openings which flows out of a region of the turning element which is not looped around by the substrate web would be unused.

In one embodiment, at least one displacement unit is provided for displacing at least one fan wheel in the interior of the tube in order to allow a selective admission of gas outlet openings with air via the interior. As a result, it is possible to apply gas only to gas discharge openings which are covered by a substrate web during operation in order to reduce leakage flows. It is thus possible to adapt to different widths of substrate webs. As a result, the total amount of air and a related energy consumption and possibly also the noise can be reduced.

The turning unit may include means for adjusting the rotational speed of the turning unit depending on web parameters such as web tension, web width, web material and / or web speed. By such a device, it is possible to easily regulate the strength of the air cushion and thus set this to different path parameters, which may be necessary, for example, in different substrate webs to provide a sufficient air cushion.

In a preferred embodiment, at least two rotatably mounted turning elements are provided, which are each arranged to a web conveying direction and also angled to each other. As a result, a twofold turn of the substrate web and thus, for example, a 180 ° turn can be provided. The turning elements can be arranged in a known manner in each case with 45 ° to the web conveying direction and crossed at 90 ° to each other. In a web running direction, a rotatably arranged intermediate roller can be provided between the turning elements, via which the web-shaped printing material is deflected after the first turn to the second turning element. Such an arrangement allows in a known manner a compact arrangement of the turning unit.

Furthermore, a device for printing a substrate web is provided which has at least one printing unit for applying a printing medium to the substrate web and a turning unit of the above type.

In the method for turning a substrate web, the substrate web is guided over at least one turning element that is angled toward a web conveying direction, and the turning element is rotated at a speed that causes the formation of an air cushion between a lateral surface of the turning element and the substrate web. These methods can achieve the advantages already mentioned above.

The turning element may be a tube having an internal space which has passage openings from the interior to the lateral surface thereof, wherein air is sucked in via the interior through the rotation of the turning element and ejected via the passage openings. As a result, the formation of the air cushion can be improved in a simple manner. In this case, it is possible to restrict the emission of air to the regions which are looped around by the substrate web by selectively applying passage openings in the tube.

For a particularly good design of the air cushion, it is possible the speed of the turning element as a function of orbit parameters, such as the web tension, the web width, the Adjust or regulate web material and / or web speed.

The invention will be explained in more detail with reference to the drawings; in the drawings show:

1 a schematic side view of a printing machine with inventive turning unit;

2 a schematic, perspective view of a turning unit according to the invention with two turning elements and an intermediate roller;

3 a schematic plan view of a range of movement of a substrate web as seen from the line A in 1 ;

4 a schematic sectional view of a turning element which is rotated in a certain direction;

5 a schematic plan view of a turning element according to a first embodiment;

6 a schematic side view of a turning element according to a second embodiment;

7 a schematic sectional view through the turning element according to 6 along the line VII-VII; and

8th a schematic sectional view similar to the 7 with an alternative configuration of the turning element.

Location indications used in the following description are primarily related to the illustrations in the drawings and therefore should not be taken as limiting. You can also refer to a preferred final arrangement. Substantially similar reference numerals are used throughout the drawings as long as the same or equivalent elements are described.

1 shows a schematic side view of a printing press 1 with a feeder / boom area 2 , a printing area 3 and a turning area 4 , The printing area 3 is between investor / boom area 2 and turning area 4 arranged.

In the investor / boom sector 2 is a first substrate roll 5 provided, from which a printing substrate 6 for printing in the printing area 3 is supplied. In the investor / boom sector 2 is also a second (not shown) Bedruckstofrolle for receiving the from the printing area 3 returning printing material web 6 provided after this in the turning area 4 was turned, as will be explained in more detail below.

In the printing area 3 is a variety of roles 8th for guiding the printing material web 6 as well as a variety of printing works 10 intended. From the roles 8th are in 1 schematically shown seven pieces, but with a larger number is usually provided, which is the substrate web 6 along a non-linear transport path through the print area 3 promotes through.

In 1 are four printing units 10 shown, so the press 1 according to 1 would be suitable for a four-color print. But it can also be a deviating number of printing units 10 be provided. The printing works 10 are preferably inkjet printers but may be of another digital type.

In the turning area is a variety of pulleys 12 as well as a turning unit 14 intended. The pulleys 12 are arranged so that they are the substrate web 6 from the printing area 4 to the turning unit 14 and of the turning unit 14 back to the printing area 4 to lead. The turning unit 14 , which will be explained in more detail below, causes a 180 ° turn of the printing material web 6 , as well as a lateral displacement of the same. Due to the lateral displacement of the printing material web 6 is it possible the printing material web 6 in opposite directions through the pressure area 4 and the printing works 10 to lead, as shown schematically in 3 is indicated. It shows 3 schematically the opposite, laterally offset movement of the substrate web 6 about a role 8th which lies in the area of a printing unit.

2 schematically shows a perspective view of the turning unit 14 with a first rotatably mounted turning element 20 , an intermediate pulley 22 and a second rotatably mounted turning element 24 , In 2 is also the substrate web 6 as shown by the turning unit 14 passed through. The first turning element 20 is with respect to a by the arrow B in 2 displayed input direction of the printing material web 6 arranged at a 45 ° angle and consists of a rotatably mounted rod or a hollow tube, which is coupled to a rotary drive, not shown, as will be explained in more detail below. The printing material web 6 is the first turning element 20 guided around and is thereby deflected by 90 °, so that it runs after the deflection at right angles to the input direction.

The intermediate deflection roller 22 is a rotatably mounted pulley, with respect to the first turning element 20 is arranged laterally offset and parallel to the input direction of the printing material 6 extends. It is arranged so that it runs after the first deflection transversely to the inlet direction of the printing substrate 6 deflects by 180 °. Thus, the substrate web after the deflection in the opposite direction but still running transversely to the input direction.

The second turning element 24 has the same structure as the first and is arranged at 90 ° to this angle. For a lateral offset of the printing material web, the first and second turning elements 20 . 24 be offset transversely to the input direction of rotation to each other. The after the Zwischenumlenkrolle 22 transverse to the input direction running substrate web 6 is the second turning unit 24 guided around and is thereby in turn deflected by 90 °, so that it runs again in the input direction. Due to the multiple deflection of the substrate web is turned by 180 °, so that the formerly upper side now facing down.

The turning elements 20 . 24 are, as already mentioned, each coupled to a rotary drive, not shown, of the turning elements 20 . 24 for example, in each case in the direction shown by the arrows C can rotate. The rotation can essentially, as shown by the arrows C in 2 is shown in the direction of the substrate web, or substantially opposite thereto, as indicated by the arrow D in 4 is indicated. By a rotation of the turning elements 20 . 24 Air is sucked into the wrap between the reversing element and printing material to form an air cushion therebetween, as indicated by the arrow E in 4 is indicated. In both cases, it is advantageous if the rotational speed of the turning element is substantially greater than the transport speed of the printing material web.

The turning elements 20 . 24 may have the same structure, so that in the following each only different embodiments of the turning element 20 be described in more detail.

5 schematically shows a plan view of a turning element 20 according to a first embodiment. In this embodiment, the turning element as a rod or as a hollow tube with a lateral surface 35 be educated. In the lateral surface 35 is a groove structure 37 formed, as shown, a circumferential spiral groove 38 having. This spiral groove promotes during the rotation of the turning element 20 the suction and distribution of air to form an air cushion between the turning element 20 and the printing material web. Although in 5 a continuous spiral groove 38 is shown as a groove structure, it should be noted that other groove structures, in particular of several different individual grooves that can be completely separated, but can also cut are conceivable. In particular, for example, opposite spiral grooves are conceivable, for example, from the ends of the turning element to a central region thereof run. On transverse grooves, ie grooves which extend transversely to the direction of rotation of the turning element may be conducive to the Ansugung and distribution of air between the turning element and printing material.

6 shows a schematic sectional view through a turning element 20 according to an alternative embodiment. In the sectional view can be seen as the substrate 6 around the turning element 20 is performed around, with the simplification of the illustration, only the actual cutting plane through the turning element 20 is shown. The turning element 20 is formed in this embodiment as a hollow tube and has a tubular body 44 , which has an outer surface 35 has and inside a cavity 48 forms. In the tube body 44 are passage openings 50 formed, which is an air flow from the cavity 48 to the lateral surface 35 enable. The surface area 35 may be substantially smooth, as shown, or may also have a structure, such as a groove structure 37 as previously described with reference to the first embodiment. In this case, the through holes 50 be arranged so that they are in the groove structure 37 open into it.

In the cavity 48 two are a fan 60 with slats or wings 65 arranged as in the schematic sectional view according to 7 you can see. In 6 only one fan is visible. The fans 60 can be designed as a radial compressor, which suck in the axial direction of air and deflect and compress them in the radial direction, or as an axial fan, suck the air axially and forward in the axial direction. Axial fans are provided in the illustrated embodiment. When using centrifugal compressors they should preferably with the through holes 50 in the tube body 44 be aligned.

The fans 60 are each rotationally fixed with the turning element 20 connected so that they turn during a rotation of the turning element 20 also rotate and thereby air in the cavity 48 and in particular to the passage openings 50 in the tube body 44 promote. The fans 60 are in opposite directions, so they with a corresponding rotation of the turning element 20 each air over axial end openings 65 . 66 of the cavity 48 aspirate and deliver to the middle of the cavity.

The fans may be stationary in the axial direction of the cavity or in the axial direction be slidable to selectively apply through holes 50 with air over the fans 60 to enable. 8th shows for example the fans 60 in a shifted position, with only certain of the through holes 50 over the fans 60 be charged with air. This makes it possible, for example, only such passage openings 50 with air, in the area of the printing material web 6 lie.

Instead of two fans 60 it is also possible only one fan 60 provide and close an axial end opening of the cavity via a corresponding wall element.

Adjacent to the lateral surface 35 of the turning element 20 is an air baffle 70 intended. The air baffle 70 owns a main part 72 , the contour of the lateral surface 20 follows over a peripheral region thereof as well as an angled thereto part 74 that turns to the turning element 20 extends. The air baffle is adjacent to a region of the lateral surface 35 of the turning element 20 arranged, the in operation not from the substrate 6 is entwined.

The main part 72 is arranged so that a substantially uniform annular gap portion between the main part 72 and the lateral surface 35 formed in the circumferential direction at one end by the angled portion 74 is limited. At the other end, the annular gap section is open, the opening pointing to the region in which the printing material around the turning element 20 is guided around. Air, in the region of the annular gap portion of the turning element 20 Exit is thus targeted to the wrap area between substrate 6 and turning element 20 steered, in a circumferential direction that of the direction of rotation C of the turning element 20 equivalent. When displayed in 6 are the running direction B of the printing material 6 and the direction of rotation C of the turning element 20 essentially the same direction. But it is possible as mentioned above, the turning element 20 opposite to the direction B of the substrate 6 to turn, in which case the air baffle 70 should be adjusted accordingly.

In the following, the operation of the turning unit according to the invention 14 explained in more detail with reference to the drawings.

During threading of the substrate web 6 This is initially the investor / boom area 2 through the pressure area 3 to the turning unit 14 and from there again through the pressure area 3 back to the boom / feeder area. In the turning unit 14 It is first in a first web running direction B to the first turning element 20 moved and guided around there. Due to its orientation in the 45 ° angle to the web running direction B of the printing substrate 6 then in a second web running direction, which runs transversely to the first web running direction B, deflected. Subsequently, the printing material web 6 over the intermediate pulley 22 in a third, deflected to the second opposite direction of web travel and then to the second turning element 24 guided around. Due to its orientation in the 45 ° angle to the third web running direction is the printing substrate 6 then deflected in a transverse to the third fourth web running direction. The first and fourth web running direction are the same direction, and the arc is turned by the deflections, so that the upper side of the page is now below.

The printing material web is then threaded through at least one corresponding drive for printing by the printing press and in particular also for turning through the turning unit 14 transported. During this transport are now the turning elements 20 . 24 each rotated over the respective drives at a sufficient speed to form an air cushion between the printing material and the lateral surface of the turning element. In this case, the turning elements 20 . 24 either in the direction of movement of the printing material web 6 or driven against it.

The formation of the air cushion can, depending on the embodiment of the turning elements by appropriate aids, such as the groove structure 38 in the lateral surface 35 of the turning element according to 5 , and / or the use of a fan 60 according to the 6 to 8th get supported. In the embodiment with fan is during rotation of the turning element 20 over the fans 60 Air in the cavity 48 of the turning element 20 sucked, and over the through holes 50 squeezed out. This supports the formation of the air cushion between the lateral surface 35 of the turning element 20 and the printing material web 6 ,

The air cushion created in this way can spread over the entire surface of the jacket 35 spread evenly. The substrate 6 is thereby redirected reduced in the respective second and fourth web conveying direction. About a displacement of the fan 60 is a selective control of individual gas outlet openings 50 over the cavity 48 possible. As a result, the gas flow from the turning element 20 out essentially to a width of the printing substrate 6 be adjusted.

The turning unit can thus, for example, a one-sided in the pressure range 3 Turn the printed substrate web in the above-mentioned manner and apply a counterpressure.

The invention has been described with reference to specific embodiments without being limited thereto. In particular, it should be noted that the embodiments can be freely combined with each other and optionally individual elements of the different embodiments can be replaced, if they are compatible.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10063025 A1 [0002]
• DE 19834679 A1 [0003]

Claims (14)

Turning unit for a substrate web, which has at least one turning element, which is angled towards a web conveying direction, marked by: a drive for rotating the turning element, wherein the drive is capable of rotating the turning element at a speed which causes the formation of an air cushion between a lateral surface of the turning element and a substrate web. Reversible unit according to claim 1, characterized by air cushioning means on the turning element, which promote the formation of the air cushion between the lateral surface of the turning element and the substrate web upon rotation of the turning element. Turning unit according to claim 2, characterized in that the air cushioning means have at least one groove structure, in particular a spiral groove structure in the lateral surface. Turning unit according to one of claims 2 or 3, characterized in that the turning element is a tube with an interior, and the Luftpolstermittel at least one fan, in particular a radial compressor in the interior, which is rotatable with the tube, and gas outlet openings from the interior to the lateral surface of the Have turning element. Turning unit according to claim 4, characterized in that the air cushioning means in the interior at least two fan wheels, which are arranged at opposite ends of the tube. Turning unit according to claim 4 or 5, characterized by at least one air guide plate, which is arranged adjacent to the turning element such that a gas stream flowing out of the gas outlet openings is deflected to the area between the lateral surface of the turning element and the substrate web. Turning unit according to one of claims 4 to 6, characterized by at least one displacement unit for displacing at least one fan wheel in the interior of the tube in order to allow a selective admission of gas outlet openings with air over the interior. Reversible unit according to one of the preceding claims, characterized by a device for adjusting the rotational speed as a function of the web tension. Turning unit according to one of the preceding claims, characterized by at least two rotatably mounted turning elements, which are each arranged to a web conveying direction and angled to each other. Apparatus for printing a substrate web with at least one printing unit for applying a printing medium to the substrate web and a turning unit according to one of claims 1 to 10. A method for turning a substrate web, which is guided over at least one turning element, which is angled to a web conveying direction, characterized in that the turning element is rotated at a speed which causes the formation of an air cushion between a lateral surface of the turning element and a substrate web. A method according to claim 11, characterized in that the turning element is a tube having an interior and that the tube has through openings from the interior to the lateral surface thereof, wherein sucked by the rotation of the turning element air over the interior and ejected through the through holes. A method according to claim 12, characterized by selectively applying passage openings in the tube. Method according to one of claims 11 to 13, characterized in that the rotational speed of the turning element is adjusted or regulated in dependence on web parameters, such as the web tension, the web width, the web material and / or the web speed.

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