EP1278637B1 - Dosing system for inking up rollers in a printing machine - Google Patents

Abstract

An ink metering system for a roller train in a printing machine which in the illustrated embodiment includes a fountain roller and a downstream train of rollers communicating with a plate or form cylinder of the printing press. One or more plating devices (12) are provided which each have a plate-like element (19) adjustably positionable with respect to a respective roller for leveling ink on the surface of the roller before or after passage through a contact zone with an adjacent roller in which ink is pulled off and separated between the rollers. The plating devices are relatively simple in construction and operation and provide stable ink guidance on the roller surfaces that noticeably improves print quality.

Description

The invention relates to a metering system for inking rollers in a printing machine, with at least one leading to a plate or forme cylinder compactor, wherein the rollers are colorable by means of paint or varnish from a reservoir, according to the preamble of the main claim. The invention is preferably used in the inking unit of a printing press with a roller rotatably arranged between a ink fountain roller and a downstream inking unit roller, in particular in a film inking unit or a lifting inking unit.

[State of the art]

A printing press with a lift inking unit is known from DE 37 06 602 A1. Here, an ink fountain roller with a metering system for the ink having color box in functional connection, as is known for example from DE 27 11 553 A1. In printing machines with a squeegee inking the ink is removed from an ink fountain roller by reciprocating a Farbheberwalze periodically in strips and fed to an inking roller of the downstream compactor. Due to the different peripheral speeds of the ink fountain roller and the ink fountain roller, there is the problem with elevator inking units that the ink fountain roller is delayed or accelerated with each impact (application) to the ink fountain roller or the ink fountain roller. In this impingement or lifting of the squeegee roller in conjunction with an accompanying color splitting in the contact zone of the rollers in addition to the ink fountain roller or on the inking roller uneven color guide during the ink transport of the ink, which has a quality-reducing effect in the print. By the color splitting of the ink between the ink fountain roller and ink fountain roller and between the ink fountain roller and downstream inking roller arise on the roll surfaces uneven surface topographies of the remaining color, which lead to quality impairments on the substrate.

From DE 38 04 204 A1 an inking unit of a printing machine with a film roll is known. Such a film roller is designed for the color transport over a film nip (first contact zone) in contact with the ink fountain roller and in a second contact zone with the downstream inking roller, the downstream roller train, so that a continuous ink transport of ink between the ink fountain roller and the inking roller of the roller in the Ink unit is feasible. The film roll is additionally associated with an intermediate roll in contact, said intermediate roll is arranged downstream of a doctor roller. The squeegee roller is an adjustable squeegee, the squeegee is dependent on the subject or in intervals to the squeegee roller on or off. The scraped off by the doctor roller ink returns to the ink fountain. This film inking unit minimizes the minimum amount of ink by removing a subset of color from an inking unit and is relatively expensive due to the additional use of rollers (intermediate roller, doctor roller). In the contact zones of ink fountain roller and film roller and film roller and downstream inking roller is carried out analogously to the described Heber inking per contact zone, a color separation of the ink, so that even in film inking on the roll surfaces uneven surface topographies of the color arise, which leads to an impairment of the print quality on the substrate.

Furthermore, from DE 196 09 946 A1 discloses a printing machine with an applicator for coloring a roller of an inking unit known. The application device consists of a paint or varnish or a comparable medium having Reservoir, which is in functional connection with a metering roller. The dosing roller is in frictional contact for ink transfer with a drivable roller and thus forms a contact zone in which a color or paint splitting takes place.

According to DE 42 41 809 A1 discloses a printing machine with a device for coloring rollers is known, the color from a reservoir under compressed air zonal in the axial direction of the roller on the lateral surface thereof supplies. In this case, no contact takes place on the part of the device with the lateral surface of the associated, inking roller. The color applied in zones forms on the surface of the inked roller a different amount of ink, which has an uneven surface topography of the color.

Such an uneven surface topography of the ink on the lateral surface of a roller is produced when the ink is torn off, for example when the ink comes out of a storage container and hits a lateral surface or after a color-splitting process (division of the ink layer) in the contact zone between two rollers or the contact zone of a roller with a stripping system, for example a paint dosing system.

From DE 199 38 301 A1 an inking unit for a printing machine for the uniform application of color is known. Assuming that there is a tension at the nip formed by two rolls, uneven ink transfer results. Such a voltage influences, for example, the line pressure in the nip of two rollers and these different line pressures cause, for example, an uneven ink transfer, which is shown on the substrate as unevenly applied color film. To improve the ink transfer at least one inking roller is associated with a Ausstreichelement, which is a

Shearing effect of the color achieved. Preferably, the Ausstreichelement is associated with a plate cylinder adjacent the inking roller and / or a Farbreiberwalze.

An inking unit for coloring the plate fixed on a plate cylinder is known from DE 84 01 569.1 U1. A metering device, consisting of a metering strip or a surface doctor blade or a metering roller, forms a relatively thick, uniform ink film on the adjacent inking roller. Excess paint drips from the inking roller into a paint container under the action of shear forces.

From DE 28 56 088 A1, another inking unit is known, which has an ink fountain roller dipping into an ink fountain. This ink fountain roller are assigned adjustable, mirror image of each other mounted doctor rollers, which act as Farbdosierelemente.

For processing a mixture of ink and fountain solution, a planographic printing system from EP 0309 681 A2 is known. A dipping roller is fed in a circuit a mixture of paint and dampening solution. The fountain roller scoops the mixture and transfers it to an adjacent anilox roller, which are connected via downstream forming rollers with a plate cylinder in operative connection. The anilox roll is associated with at least one doctor blade for stripping off the excess mixture of ink and fountain solution. The excess mixture is recycled in the direction of the fountain roller in the circulation.

OBJECT OF THE INVENTION

The invention is based on the object to provide a metering system of the type mentioned, which achieves a uniform, stable color guide (or paint guide) on at least one roll surface with little effort and noticeably improves the print quality.

The object is achieved by the training features of the independent claim. Further developments emerge from the dependent claims.

It has been found that on the outer surface of a color-leading (the term also includes a paint-carrying roller) roller after tearing (shearing) of paint (or paint) in a contact zone no uniform color / paint distribution - viewed over the roll width - is present. On the roller there is an uneven surface topography of the paint (paint), which is characterized by color peaks or color dome and color valleys (or paint tips, paint dome, paint valleys) on the outer surface of a paint-carrying roller. For example, in an ink fountain roller, after the color separation (separation of the ink layer) in a contact zone with another roller, such as a squeegee or film roller, by tearing off paint / lacquer, especially in thread-like tearing, no uniform color / lacquer distribution over the roll width considered before, but an uneven surface topography of the residual color (or the residual paint) on the lateral surface of the ink fountain roller. This also applies to within a Farbdosiersystems of Farbdosierelementen generated color zones with zonal defined layer thickness, since here also a tearing off of paint or lacquer as a result of the color (the paint) separating shear forces occurs.

A first advantage of the invention lies in the fact that with an uneven surface topography (peaks, crests and valleys) of paint (paint), which results from a previous tearing off of paint (paint), at least one ink-carrying (or paint-carrying) roller at least one Plating is assigned circumferentially. The plating causes a change in shape (plastic shaping) of the color tips or color caps and the color valleys (or paint tips, Lackkuppen, paint valleys) within the present surface structure of the paint (or the paint). The change in shape represents a micro-transformation of the surface structure of the paint (the paint). In such a change in shape of the surface structure of the paint (the paint), the color tips or paint crests (paint tips, paint crests) slide into the color valleys (paint valleys), i. Within the color layer of the color structure (of the lacquer structure) sliding processes occur, which bring about the plastic shaping, so that an approximately flat surface topography in a defined layer thickness can be achieved

According to the invention in the plastic shaping by a plating, it is that the paint or the paint no shearing (shearing or dicing effect) is subject, as a shearing action in turn leads to an unwanted tearing of paint or varnish and thus to an uneven surface topography.

The achieved by the plating relatively flat surface topography of paint (or paint) causes color / density variations on the substrate are significantly reduced, so that the print / gloss or sealing quality is noticeably improved. As a result, there is a flat surface topography of the paint or residual paint or the paint on the lateral surface of the respective roller over the roll width before the roll comes into contact with a subsequent contact zone (eg a cleavage site).

With such a plating device, this uneven surface topography of the paint or residual paint or of the paint is clearly leveled on the associated roller, for example the ink fountain roller, so that a uniform surface topography of the paint or residual paint or of the paint for a uniform, stable color change. / Paint guide in the compactor is achievable.

When using a plating device, in particular on a ink fountain roller, an excess of, for example, printing ink in the metering gap (gap between ink metering system, for example ink slides and ink fountain roller) is drawn through the metering gap to a significantly reduced extent.

It is also advantageous that, in particular, the parameters which change during the printing process, such as printing speed, temperature, ink quantity, hydrodynamic pressure in the ink fountain and the viscosity of the ink or lacquer, are perceptibly reduced according to the invention as possible disturbing variables by the use of a plating device.

Another advantage is that the plating device according to the invention is not limited to an ink fountain roller. Rather, the arrangement of plating is also feasible in other ink-carrying (including paint-leading) rollers of an inking unit. In this case, according to the invention, in each case at least one plating device of a roller assigned. Alternatively, several plating can be arranged to form a roll.

It is also advantageous that by means of the plating uniformly leveled surfaces of the color or residual color or the paint lead to uniform conditions in the subsequent color / paint cleavage (Farbdosiersystem) in the ink fountain or uniform cleavage ratios between adjacent rollers (contact zones) itself and thus the print quality is noticeably improved. With the leveling of paint or paint on the lateral surface of a roller, a homogeneous ink layer is created, which is better dosed. In this case, a smaller distance position of the Farbdosierelemente the Farbdosiersystems to the roller at the same color density (paint density) can be realized and it is a continuous flow of color achievable.
Furthermore, the inking unit according to the invention by the independently controllable speed and possibly direction of rotation of the roller, for example the film roller, greatly reduces the disturbance of the ink flow, whereby a better adaptation of the ink flow to the printing speed can be achieved.

Furthermore, there is the possibility of saving ink rollers, depending on the geometry of the compactor in the inking unit. As a result, a more uniform surface topography of the residual paint or of the residual paint on a roll at fewer nip points to achieve defined layer thicknesses of the ink film on the plate cylinder can be achieved. This also a shortening of the compactor can be realized.

The plating device serves to create a relatively flat surface topography on the lateral surface of an associated paint or paint-guiding roller. In the area of the plating device is a tear off / shearing of paint or to avoid lacquer on the lateral surface of the corresponding roller, since otherwise again uneven surface topographies arise. The formation of the plating device is not limited to one or more mechanical plating device (s) having one or more plating elements.

[Examples]

Fig. 1

die Anordnung eines Dosiersystems zum Einfärben eines Farbwerkes,

Fig. 2

ein Farbdosiersystem in Funktionsverbindung mit einer Farbkastenwalze,

Fig. 3

ein Dosiersystem mit einer Farbkastenwalze und einer Farbspendeeinrichtung,

Fig. 4 a,b

Darstellungen von Oberflächentopographien.

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

Fig. 1

the arrangement of a dosing system for coloring an inking unit,

Fig. 2

a paint dosing system operatively connected to an ink fountain roller,

Fig. 3

a dosing system with an ink fountain roller and a paint dispenser,

Fig. 4 a, b

Representations of surface topographies.

The offset printing unit of a sheet-fed rotary printing press consists essentially of an inking unit with an ink fountain 9 with a Farbdosiersystem 8, eg Farbschiebem, functionally connected ink fountain roller 1, further a squeegee 2 or a film roller 6 and a first inking roller (rotationally and axially iridescent drivable) trained inking roller 3 a downstream Rolling compact 7. This compactor 7 leads to the plate cylinder (or forme cylinder) and is known to have a plurality of rollers, of which, by way of example, the second inking roller 5 (rotationally and axially oscillatingly drivable) with intermediate transfer rollers 4 are listed (FIG. 1).

At least one roller (1 to 6) of the inking unit is at its outer surface at least one plating 12 after a contact zone 10 in which a color separation or a color separation is carried out, to the lateral surface of the roller (1 to 6) adjustable - and preferably off - allocated adjacent. The plating device 12 extends substantially parallel over a full roll width 15th

Preferably, the plating device 12 can be adjusted by means of a force F to the lateral surface of the associated roller (roller 1 to 6). By means of the plating device 12 is preferably a uniform surface pressure over the roll width 15 (roller 1 to 6) on the color or residual color, alternatively, the coat leading surface of the roller 1 - 6 applied.

In a preferred embodiment, in the direction of rotation of the roller 1 to 6, the plating device 12 in its direction tangent or secant to the lateral surface of the roller 1 - 6 can be adjusted.

Such a plating device 12 is formed by a over the roll width 15 extending, in the direction of rotation of the roller 1 to 6 preferably tangentially positive employed plating element 19, which is detachably received in a holder 20 and in the axial direction over the entire roll width 15 parallel to the lateral surface of the Roller 1 to 6 extends. The holder 20 of the plating element 19 is preferably mounted on both sides in a frame arranged in the pivot 21, preferably pivotally mounted about the axis of the rotary joint 21.

In a preferred embodiment, the plating element 19 or the plating device 12 is in functional connection by means of at least one, preferably adjustable pressure spring supported on the frame side. In particular, the plating element 19 is preferably loaded by a force F. Alternatively, instead of the compression spring, for example, a pneumatically actuated working cylinder or other means F generating means can be used. Likewise, depending on the arrangement, the plating element 19 by use of its own weight with the associated roller 1 - 6 in functional connection, without a shear effect on the lateral surface or the residual color (residual paint) to produce. In a further embodiment, the plating device 12 is also arranged with a minimum distance to the lateral surface of the roller 1 to 6 in order to achieve a flat surface topography.

The plating element 19 ends with its free end preferably on a surface normal N (tangent point or secant point) of the respective associated roller 1 to 6. In a further embodiment, the plating element 19 leads tangentially in the direction of rotation of the roller 1 - 6 slightly beyond the lateral surface, said a tearing of paint or varnish is to be avoided.

Preferably, in the present example, the plating device 12 according to the invention is associated at least adjacent to the ink fountain roller 1 (eg, FIG. 2), which can be colored, for example, with an offset printing ink. The plating device 12 is in the direction of rotation of the ink fountain roller 1 with axis 16 after a contact zone 10 with an adjacent lifting roller 2 or film roller 6 and 8 arranged tangent-shaped before the Farbdosiersystem. This plating device 12 levels the uneven surface topography of the residual ink remaining on the surface of the ink fountain roller 1 after the contact zone 10 of the squeegee roller 2 or film roller 6, before the residual ink comes into renewed contact with the (new) ink present in the ink fountain 9 and the ink dosing system 8 ,
This is in the direction of rotation of the ink fountain roller 1 before the Farbdosiersystem 8 a level surface topography of color on the lateral surface of the ink fountain roller 1 and a possible color passage in the color dosing 8 is noticeably reduced. Furthermore, a possible Farbdichteschwankung on the substrate is already significantly reduced by the use of a plating 12 on the ink fountain roller 1. The planar Oberflächentopograhie in turn leads to always the same conditions in a contact zone in the subsequent dosing of ink in the ink fountain 9 with a Farbdosiersystem 8 or the same color cleavage ratios in a contact zone 10 of two rollers, for example of ink fountain roller 1 and squeegee. 2

The use of a plating device 12 is not limited to an ink fountain roller 1. Rather, the arrangement of plating 12 can also be realized on other rollers 2-6 of the inking unit. Preferably, the arrangement of further plating devices 12 (in addition to at least one plating device 12 on the ink fountain roller) can be realized in rollers 2-6 of the inking unit, which are arranged more remote from the plate cylinder. This is because of these rollers - for example in the area bounded by the film or lifting roller 6.2 and the second inking roller 5 - greater layer thicknesses are transmitted and generated by single or multiple plating 12 planar surface topographies most significantly reduce possible color density variations on the substrate.
In this aspect, in addition to the arrangement of the plating device 12 to the ink fountain roller 1 in addition an arrangement of a plating device 12, for example, on the lifting roller 2 or the film roller 6 can be realized. In the direction of rotation of lifting or film roller 2.6 is after the contact zone 10 with the ink fountain roller 1 and in front of the contact zone 10 of the subsequent inking roller 3 (first inking roller) preferably tangentially in the direction of rotation of Heber- / Filmwalze 2.6 another plating 12 set arranged.

In a further embodiment, in addition to the arrangement of the plating 12 at least on the ink fountain roller 1 additionally associated with a further plating 12 of the inking unit 3 and in the direction of rotation of this inking roller 3 after the contact zone 10 with the lifting roller 2 or film roller 6 and before the contact zone 10 at least one of Inking roller 3 downstream roller, for example, at least one transfer roller 4, the inking unit preferably arranged tangent-shaped in the direction of rotation of the inking roller 3 adjustable.

In a further embodiment, in addition to the arrangement of the plating 12 at least on the ink fountain roller 1 in addition to a further plating 12 at least one drivable roller, preferably associated with the second ink roller 5 of the inking unit. In the direction of rotation of the inking roller 5 after the contact zone 10 with an immediately adjacent roller, preferably a transfer roller 4, and preferably before the contact zone 10 with another immediately adjacent roller of the inking in the direction of rotation of the corresponding drivable ink roller 5 at least one further plating 12 preferably tangent-like arranged.

The mode of action will initially be explained on the training shown in Fig. 2. In the ink fountain 9 is a supply of ink, in the direction of rotation of the ink fountain roller 1, this is immersed and colored. In the following in the direction of rotation contact zone 10 is carried out by the Farbdosiereinrichtung 8 a tear of ink and inked ink fountain roller 1 promotes the remaining ink to the next contact zone 10. This contact zone 10 is formed by the ink fountain roller 1 and the lifting roller 2 (alternatively, the film roller (6) In this contact zone 10, a color splitting takes place, so that a color layer 13 remains in a defined layer thickness as residual ink on the ink fountain roller 1 and a color film of defined layer thickness is transferred to the squeegee roller 2 or film roller 6.

After the contact zone 10 is shown in FIG. 4a, the residual color (ink layer 13) as an uneven surface topography in the form of color peaks, color dome 14 and color valleys 18 on the outer surface of the ink fountain roller 1 before. FIG. 4a shows these surface topography in the rolling width 15 having a first layer thickness h ₁ and, for example, an ink fountain 17. The ink fountain roller 1 happens now in the rotational direction, the plating device 12, which causes the deformation (plastic molding) of the color peaks, Color studs 14 and the color valleys 18, and as a result, according to FIG. 4, there is a relatively flat surface topography with a second layer thickness h ₂ . The relationship of the layer thicknesses is always: h ₁ > h ₂ . The set color profile with, for example, the color zone 17 remains substantially preserved.

The object according to the invention additionally assumes that in the direction of rotation of a colored roller 1-6 in front of a contact zone 10 in which a color separation or a color splitting, the color or residual color or lacquer on the lateral surface of this roller (s) 1 - 6 by means at least one plating device 12 is leveled. Depending on the design of the inking unit is thus before the first contact zone 10, in which a color splitting takes place, a leveling of the color or residual color or the paint feasible.

For example, this is the case according to FIG. 3, when ink / lacquer is supplied by demolition from a storage container of a color dispenser 11, for example a color cartridge, directly to the outer surface of the associated roller, preferably the ink fountain roller 1, ie the ink fountain roller 1 is inked, and in the direction of rotation of the roller 1, a Farbdosiersystem 8, in which a tearing off of paint (paint) takes place, followed. In this embodiment, the plating 12 is arranged in the direction of rotation of the ink fountain roller 1 after the ink dispenser 11 and before the ink metering 8 to the ink fountain roller 1 adjustable.
Furthermore, in the direction of rotation of the colored ink fountain roller 1 (and / or further rollers 2-5) after the first contact zone 10 in which a color separation or a color splitting, the uneven surface topography of color or residual color (lacquer, residual lacquer) on the lateral surface of the ink fountain roller 1 are leveled by means of plating 12 and then the surface topography leveled on the lateral surface of a second contact zone 10 are fed, in which a color separation (lacquer tear) or a renewed color / lacquer cleavage takes place.

In development, at least one colored in the direction of rotation Roller 1 - 6 after the second contact zone 10 in which a color separation / color splitting takes place and before the first contact zone 10 in a color separation or a color splitting the residual color or the residual paint on the lateral surface of this roller (1 - 6) are leveled ,

If the roller 1 - 6 with multiple contact points 10 in which a tearing of the paint or the paint is in contact, the corresponding roller 1 - 6 are at least one, preferably also several plating 12, in the direction of rotation of the respective roller 1-6, respectively allocate 10 before the next contact point.

When arranging at least one plating device 12 in the area of the ink fountain roller 1 in the direction of rotation in front of the ink metering system 8, the plating device 12 can also be arranged dipping into the ink fountain 9.

The plating system 12 according to the invention on each roller 1 - 6 on and off arranged.

[REFERENCE LIST]

1

Ink fountain roller

2

vibrator roller

3

Ink roller (first ink roller)

4

Transfer roll

5

Second ink roller

6

film roller

7

drum compactor

8th

ink metering system

9

paintbox

10

contact zone

11

Color dispensing device

12

plating

13

coat of paint

14

Color tip, color tip

15

roll width

16

axis

17

color zone

18

Farbtal

19

plating member

20

bracket

21

swivel

F

force

h ₁

first layer thickness

h ₂

second layer thickness

N

surface normal

Claims (13)

1. Metering apparatus for inking rolls in a printing press, having at least one roll train (7) which leads to a plate or forme cylinder, it being possible to ink one roll (1) by means of ink or varnish from a reservoir vessel, and the said roll (1) being assigned an adjustable ink metering system (8), characterized in that, in the rotational direction of a roll (1 to 6) which carries ink or varnish and is an ink fountain roll (1), a ductor roll (2), a film roll (6), a transfer roll (4), an inking-unit roll (3) which is arranged behind the ductor or film roll (2, 6), or an ink distributor roll (5), after a contact zone (10) in which ink/varnish is torn off or ink/varnish splitting takes place, a flattening device (12) is arranged such that it can be set parallel against the circumferential surface of the said roll (1 to 6), and in that a shape change of the ink or of the varnish which is present on the roll (1 to 6) can be achieved by means of the flattening device (12), so that the result is a planar surface topography of the ink or of the varnish in a defined layer thickness.
2. Metering apparatus according to Claim 1, characterized in that a flattening device (12) is arranged such that it can be set parallel against the circumferential surface of the roll (1 to 6), in the rotational direction of the roll (1 to 6) in front of a contact zone (10), in which ink/varnish splitting takes place.
3. Metering apparatus according to at least Claim 1, characterized in that the flattening device (12) is assigned to an ink fountain roll (1) and is arranged such that it can be thrown on with respect to the ink fountain roll (1) after the contact zone (10) with a ductor roll (2) or a film roll (6) and in front of an ink metering system (8) in the rotational direction of the ink fountain roll (1).
4. Metering apparatus according to at least Claim 1, characterized in that the flattening device (12) is assigned to the ductor roll (2) or the film roll (6) and is arranged such that it can be thrown on, in the rotational direction of the ductor/film roll (2, 6), after the contact zone (10) with the ink fountain roll (1) and in front of the contact zone (10) of the inking-unit roll (3) arranged behind it.
5. Metering apparatus according to at least Claim 1, characterized in that the flattening device (12) is assigned to the inking-unit roll (3) and is arranged such that it can be thrown on, in the rotational direction of the inking-unit roll (3), after the contact zone (10) with the ductor roll (2) or film roll (6) and in front of the contact zone (10) of a roll (4) of the roll train (7) which is arranged immediately behind the inking-unit roll (3).
6. Metering apparatus according to at least Claim 1, characterized in that the flattening device (12) is assigned to at least one drivable roll (3, 5) of the roll train (7) and is arranged such that it can be thrown on, in the rotational direction of the roll (3, 5), after the contact zone (10) with a directly adjacent roll of the roll train (7) and in front of the contact zone (10) with a further directly adjacent roll of the roll train (7).
7. Metering apparatus according to at least Claim 1, characterized in that the flattening device (12) can be set against the circumferential surface of the roll (1 to 6) by means of a force (F).
8. Metering apparatus according to at least Claim 1, characterized in that a uniform surface pressure can be applied over the width of the roll (1 to 6) by means of the flattening device (12).
9. Metering apparatus according to at least Claim 1, characterized in that, in the rotational direction of the roll (1 to 6), the flattening device (12) has a flattening element (19) which extends over the entire roll width (15) and is arranged releasably in a holding device (20).
10. Metering apparatus according to at least Claims 1 and 9, characterized in that the holding device (20) is mounted on both sides in a rotary joint (21) which is fixed to the frame.
11. Metering apparatus according to at least Claims 1 and 9, characterized in that the flattening element (19) is functionally connected to a compression spring which is supported on the frame side.
12. Metering apparatus according to at least Claims 1 and 9, characterized in that a free end of the flattening element (19) ends in the form of a tangent or secant on the circumferential surface of the roll (1 to 6) at a tangent or secant point.
13. Metering apparatus according to at least Claims 1 and 9, characterized in that a free end of the flattening element (19) ends at a slight spacing from the circumferential surface of the roll (1 - 6).

Images