DE10125379A1 - Paper web coating roller compression regulated by jack pressure with pressure sensor in pressure transmission system - Google Patents

Abstract

A parallel double-roller (14, 16) assembly spreads a coating of liquid or paste to a web (10) of paper or carton. The assembly has a jack (26) which applies a converging force to the rollers and a sensor (36) determining the force. The sensor (36) is esp. positioned in the compression force transmission system between the jack and rollers. The system has two or more compression transmission paths each incorporating a pressure sensor. The compression applied by each jack is individually variable. One of the rollers is fixed but rotates within a machine frame. The second roller rotates within the frame but moves in response to pressure from the jack (26) applied through a lever.

Description

The invention relates to a device for pressing together two axially parallel, approachable rollers in a coating machine for the flat application of a liquid to pasty application medium on a running material web, in particular made of paper or cardboard

• - Force generating means for providing a force, which at least partly in a power transmission path running over the rollers can be transferred between the rollers while generating a pressing force, and
• - Sensor means for detecting the pressing force between the rollers.

Such a device is for example from EP 0 978 589 A2 known. In this known solution, the between the rollers transmitted pressure and in particular their axial distribution Sensors detected, which in the roller body of one of the rollers, especially in the jacket of the roller or a coating applied to the jacket, are embedded near the surface. The line pressure between the rollers can be detected with good accuracy in this way. An exact Capturing the line pressure is important because of the stroke result depends essentially on the strength of the roller pressure. The embedding The sensors in the roller body have the disadvantage that this is the Manufacture of the roller difficult and expensive. In addition, must be taken into account that from time to time a grinding of the outer Functional layer of the roller may be necessary to prevent damage in the Fix roller surface. Are the sensors close to this  Functional layer arranged or even embedded in this, so this can As a result, the outer layer of the roller is only on a small part their strength is available for grinding and accordingly early the roller may need to be replaced.

The object of the invention is therefore a device of the generic type Kind of training in such a way that the above problems are avoided can.

To achieve this object, the sensor means are in the from the power generation means running over the rollers Power transmission path outside the roller bodies of the two rollers arranged. By moving the sensor means out of the roller bodies of the rollers, the manufacture of the rollers is less complex and costly. Because no sensors in the roller body need to be embedded, the possibility is opened on Standard rollers. Even the occasional grinding of the Rolling can thus be carried out regardless of the sensor means become. Nevertheless, the one that prevails between the rollers can continue Contact pressure can be measured directly because the sensor means in the Transmission path of the pressing force are arranged.

If we are talking about a roller body of a roller, then including essentially the barrel-shaped (generally hollow cylindrical) usually with a covering made of elastic or hard material covered structures understood that forms the actual roller. Bearing journals, which serve for the rotatable mounting of the roller, are thereby not counted to the roll body.

It is basically conceivable that the power generation provided force essentially entirely on that of the rollers running power transmission path as the only power transmission path  is transmitted. However, it can also be provided that the of the force provided to the force generating means on the over the rollers running power transmission path and at least one other Power transmission path branches. In this case, the sensor means in the power transmission path running over the rollers after it Branch from the further power transmission path may be arranged.

If there are several parallel power transmission paths for those of the Provided force generating means are provided, so there is an advantageous way to influence the effective pressing force between the rollers in that the ratio of the over the different Power transmission paths transmitted forces is changeable. For this purpose, in the further force transmission path preferably arranged sling means, which change the ratio of the across the various Power transmission paths transmitted forces are adjustable.

Basically, it is sufficient to run along the one running over the rollers Power transmission path only at one point to the transmitted power measure up. This point can be the first following the roller body two rollers or after the roller body of a second following the two rollers. But it is also possible to do a force measurement at the same time in several places along the one running over the rollers Make transmission path. For this purpose, the sensor means at least one in front of the roller body of the first roller arranged sensor and at least one after the roller body of the second sensor arranged roller include. It is advantageous here that the measured values supplied by the various sensors can be compared with each other, so that the sensors check each other, so to speak. The security and accuracy of the Force measurement can be increased in this way.  

In a preferred embodiment of the invention is one of the two Rolling on a stand relative to this, but rotatable stored, with the other roller rotatably mounted on the stand Bearing lever is attached, which for mutual approximation of the two rollers is pivotable relative to the stand. The In this embodiment, force generating means engage on the Bearing lever.

The sensor means can then comprise at least one sensor, which is attached to the bearing lever or the stand. When designing of the bearing lever or stand and the positioning of the sensor it must be ensured that the sensor has exactly that force component detected, which is introduced into the pair of rollers.

Alternatively or additionally, the sensor means can have at least one sensor comprise, which is arranged in a storage area of one of the rollers. For example, the sensor can be on a bearing journal concerned roller be attached. But it can also be a one Bearing journal of the roller in question enclosing the rolling bearing Sensor. In the latter case, the sensor can be in the rolling bearing be integrated or be attached to an outer ring of the rolling bearing. It is also conceivable that the sensor is attached to a bearing housing is in which a bearing journal of the roller in question enclosing rolling bearing is added.

Furthermore, the sensor means can alternatively or in addition to the above identified possible sensor locations include at least one sensor, which is housed in a separately manufactured sensor module, this sensor module between the stand or the bearing lever and a bearing kit for a bearing journal on the stand or the Bearing lever held roller is installed. Such sensor modules are in Form of mechanically self-contained load cells available on the market  available. For the storage of the rollers, standard, standardized bearing kits can be used, which reduces costs effect.

The sensor means can be used for force sensing at least one tension and / or pressure sensitive element, especially a strain gauge, include. Such sensor elements are of various designs known and have proven to be robust, reliable and in practical use proven precisely. Of course you can also on others Measuring principles based sensor elements are used, provided they a sensor signal representative of the pressing force between the rollers are able to provide.

Expediently, one which is responsive to the sensor means and Electronic control unit controlling the force generating means is provided be used to maintain a predetermined Setpoint of the pressing force between the rollers is set up. there can the force generating means in the area of both axial ends of the Roll pairing each at least one independently controllable, in particular comprise hydraulic power device and the sensor means for each other Independent detection of the pressing force in both axial end areas the roller pairing. The control unit can then such control of the power devices can be set up that on the axial Extension of the roller pair an essentially constant Line pressure between the rollers results, as is the case with numerous Use cases is desired. Nevertheless, it is not excluded that To program the control unit so that it is in the two axial End areas of the roller pairing different values of Result in line pressure.

The device according to the invention is preferably used in a Coating determined where the web of material between the two  Rolls is passed and at least one of the rollers for transfer of the application medium on the material web.

Below are some embodiments of the invention based on the attached drawings described in more detail. In it represent:

Fig. 1 shows schematically an overall view of a coating plant with a sensor arrangement for detecting the prevailing between a pair of rollers line pressure,

Fig. 2 shows schematically a storage area of one of the rollers to explain variants of the sensor arrangement.

The coating system shown in FIG. 1 is used for the indirect application of a liquid to pasty application medium, for example a pigmented coating color or a surface glue, on both sides to a running material web 10 made of paper or cardboard. The material web 10 moves through an application nip 12 , referred to in technical jargon as a nip, which is formed between two adjacent rollers 14 , 16 . The rollers 14 , 16 are arranged with their axes 18 , 20 parallel to one another. One of the rollers - here the roller 16 - serves as a so-called fixed roller, while the other roller - here the roller 14 - forms a so-called moving roller. This means that the roller 16 is rotatable about its axis 20 , but is otherwise arranged in a fixed position, while the moving roller 14 is approachable to and detachable from the fixed roller 16 . For this purpose, the fixed roller 16 is held on a machine stand 22 firmly anchored to the floor. A bearing lever 24 pivotally attached to the machine stand 22 supports the moving roller 14 . A force device arrangement 26 , which preferably has at least one hydraulic piston-cylinder unit 28 in the region of both axial ends of the pair of rollers 14 , 16 , serves to pivot the bearing lever 24 and thus to bring the moving roller 14 closer to and press it against the fixed roller 16 . The force device arrangement 26 can be controlled by an electronic control unit 30 of the coating mechanism, wherein the individual force devices of the force device arrangement 26 can expediently be controlled independently.

The coating medium with which the material web 10 is to be coated is first applied to the rollers 14 , 16 in a manner which is not shown in detail, but is generally known. From there, the coating medium is then transferred to the material web 10 . Doctor units 32 , 34 are used for metering and equalizing the coating medium applied to the rollers 14 , 16 . Such doctor blades are widely known in the prior art and require no further explanation in connection with the present invention.

The quantity and thickness of the medium applied to the material web 10 are influenced by the niplast prevailing in the application gap 12 , that is the pressing force that is transmitted between the rollers 14 , 16 . In order to know this Niplast, the coating unit is equipped with a sensor arrangement that directly detects the pressure applied. The sensor arrangement is arranged in the transmission path of the pressing force and measures the latter before it is introduced into and / or after it emerges from the roller bodies of the roller pair 14 , 16 . Specifically, the sensor arrangement in the exemplary embodiment in FIG. 1 has at least one force sensor 36 , which is attached to the bearing lever 24 or the stand 22 and supplies its sensor signal to the control unit 30 . In principle, it is sufficient to provide only one such force sensor 36 along the transmission path of the pressing force. It is per se indifferent whether the force sensor 36 is attached to the bearing lever 24 or to the stand 22 , provided that it is aligned and positioned in such a way that essentially only the force component to be detected, but this passes completely through it. The choice of the stand 22 as the attachment location for the force sensor 36 can, of course, have the advantage that the cabling of the force sensor 36 does not have to be routed through a pivot point, which, however, is not a serious problem with the technology available today. A preferred choice for the attachment location of the force sensor 36 can nevertheless arise if the material web 10 is not - as in Fig. 1 - straight one in the application nip 12 and runs out of this, but at least one of the rollers 14, 16 is partially wrapped. Then the force sensor 36 is preferably attached to that of the components: bearing lever 24 and stand 22 , which the roller carries with less wrap through the material web 10 . In this way, the influence of the web tension on the force measurement can be minimized.

Nevertheless, both the bearing lever 24 and the stand 22 can each be provided with at least one force sensor 36 , which makes it possible to check the measured pressing force by comparing the sensor signals. The bearing lever 24 or the stand 22 are expediently provided with a force sensor 36 axially on both sides of the roller pair 14 , 16 in order to be able to obtain at least approximately information about the axial distribution of the niplast.

The force sensor 36 can, for example, be constructed from strain gauges which are applied to the outside of the bearing lever 24 or the stand 22 and which detect the elastic deformations of the bearing lever 24 or the stand 22 which occur as a result of the mutual pressing of the rollers 14 , 16 . The interconnection of several such strain gauges in bridge circuits is known per se from the prior art.

Depending on the measured actual pressing force, the control unit 30 activates the power device arrangement 26 in a suitable manner in order to obtain a desired pressing force, for example given by an operator by input on a control panel, and to maintain it in the context of an automatic control. In most applications, the pressure to be set will be the same in both axial end regions of the pair of rollers 14 , 16 , so that a line pressure that is constant over the machine width results. In addition to determining the force, the control unit 30 can also be designed to determine the vibration behavior of the roller pair 14 , 16 from the sensor signals and to control the force device arrangement 26 in the sense of influencing the vibration.

The force made available by the force device arrangement 26 can essentially only be transmitted via the rollers 14 , 16 as the only force transmission path. However, the coating mechanism can be made stiffer overall and less susceptible to vibrations if the force provided by the power device arrangement 26 is transmitted over several power transmission paths. For this purpose, a pair of interacting stop bodies 38 , 40 are shown in broken lines in FIG. 1, one of which is arranged on the bearing lever 24 and the other of which is arranged on the stand 22 . One of the stop bodies 38 , 40 - here the stop body 38 - can be adjusted by means of a positioning member 42 which can be controlled by the control unit 30 , for example a spindle lifting member. Accordingly, two force transmission paths are available for the force provided by the force device arrangement 26 : a first, which runs over the rollers 14 , 16 , and a second, which runs over the stop bodies 38 , 40 . By adjusting the position of the stop body 38 , the ratio of the forces transmitted via the two force transmission paths and thus the effective pressing force between the rollers 14 , 16 can be changed.

The at least one force sensor 36 lies in the force transmission path running over the rollers 14 , 16 at a point after its branching off from the second force transmission path and before it is reunited with the second force transmission path. In this way, the actual pressure force is still detected directly by the force sensor 36 , and any tensions or thermally induced deformations within the coating system cannot falsify the measurement result.

In the working operation of the coating mechanism, the force device arrangement 26 preferably always applies a maximum force to the bearing lever 24 . The desired pressing force is then set by suitable adjustment of the stop body 38 , depending on the sensor signal supplied by the force sensor 36 . The further the stop body 38 is adjusted to the right in FIG. 1, the greater the proportion of the force transmitted via the stop body 38 , 40 of the total force available. As far as the latter remains unchanged, the pressing force then decreases accordingly. The reverse applies when the stop body 38 is moved to the left in FIG. 1.

It goes without saying that a pair of such stop bodies 38 , 40 is arranged on each of the two axial sides of the roller pair 14 , 16 , these pairs preferably being independently adjustable by means of a positioning member 42 .

In FIG. 2, components that are the same or have the same effect are provided with the same reference symbols as in FIG. 1, but supplemented by a lower case letter. Since only differences from the previous exemplary embodiment are to be dealt with in the following, reference is made to the preceding description of FIG. 1 for explanations of these components.

Fig. 2 shows an embodiment in which one or more sensor elements, not shown in detail, such as strain gauges, are housed in a load cell 36 a, which forms a mechanically closed, separate component that between the bearing lever 24 a and a bearing kit 46 a is installed, which serves to support an axial journal 48 a of the roller 14 a. (It goes without saying that the bearing lever 24 a and the roller 14 a are selected here only by way of example. Of course, such a load cell can also be installed between the machine stand and the other roller.) The bearing kit 46 a has a bearing housing 50 a and one therein Rolled bearing 52 a recorded with an inner ring 54 a and an outer ring 56 a. The load cell 36 a can be, for example, a commercially available force measuring block such as that sold by FMS Force Measuring Systems AG, Switzerland. The use of the load cell 36 a has the advantage that the required force passes exactly through it and standard components can be used for the bearing housing 50 a and the roller bearing 52 a.

As an alternative to a load cell, the journal 48 a could also be expanded to a measuring pin by attaching one or more suitable sensor elements to it. This is indicated by dashed lines at 36b in FIG. 2. It is also possible to attach such sensor elements in the bearing housing 50 a. The bearing lever 24 a could then remain structurally unchanged, and a standard component could in turn be used for the rolling bearing 52 a.

The roller bearing 52 a can be considered as a further alternative measuring point for detecting the pressing force. Here, one or more sensor elements can be retrofitted, for example on the outer ring 56 a. The rolling elements of the rolling bearing 52 a cause elastic deformations of the outer ring 56 a under load, which are a measure of the transmitted force and can be detected. Finally, it is conceivable to use a roller bearing 52 a with an integrated force sensor, that is, a bearing that is already prepared by the manufacturer with suitable force detection elements. The bearings of existing coating units can then be replaced by such "measuring bearings" without any design changes.

Claims (21)

1. Device for mutually pressing two axially parallel, approachable rollers ( 14 , 16 ) in a coating unit for the flat application of a liquid to pasty application medium on a running material web ( 10 ), in particular made of paper or cardboard
Force generating means ( 26 ) for providing a force which is at least partially transferable in a force transmission path running over the rollers ( 14 , 16 ) while generating a pressing force between the rollers ( 14 , 16 ), and
Sensor means ( 36 ; 36 a; 36 b) for detecting the pressing force between the rollers ( 14 , 16 ),
characterized in that the sensor means ( 36 ; 36 a; 36 b) are arranged in the force transmission path running from the force generating means ( 26 ) via the rollers ( 14 , 16 ) outside of roller bodies of the two rollers ( 14 , 16 ). 2. Device according to claim 1, characterized in that the force provided by the force generating means ( 26 ) branches onto the force transmission path running via the rollers ( 14 , 16 ) and at least one further force transmission path and that the sensor means ( 36 ) in which via the Rollers ( 14 , 16 ) extending power transmission path are arranged after its junction from the further power transmission path. 3. Device according to claim 2, characterized in that the ratio of over the different power transmission forces is changeable. 4. The device according to claim 3, characterized in that stop means ( 38 , 40 ) are arranged in the further force transmission path, which are adjustable to change the ratio of the forces transmitted via the different force transmission paths. 5. Device according to one of claims 1 to 4, characterized in that the sensor means ( 36 ; 36 a; 36 b) comprise at least one sensor ( 36 ) which, based on the force transmission direction of the force transmission path running over the rollers ( 14 , 16 ) in front of the roller body a first one ( 14 ) of the two rollers ( 14 , 16 ) is arranged. 6. Device according to one of claims 1 to 5, characterized in that the sensor means ( 36 ; 36 a; 36 b) comprise at least one sensor ( 36 ) which, based on the direction of force transmission of the force transmission path running over the rollers ( 14 , 16 ) after the roller body of a second following ( 16 ) of the two rollers ( 14 , 16 ) are arranged. 7. The device according to claim 5 and 6, characterized in that the sensor means ( 36 ; 36 a; 36 b) at least one sensor ( 36 ) arranged in front of the roller body of the first roller ( 14 ) and at least one after the roller body of the second roller ( 16 ) arranged sensor ( 36 ). 8. Device according to one of claims 1 to 7, characterized in that one ( 16 ) of the two rollers ( 14 , 16 ) on a stand ( 22 ) relative to this, but rotatably mounted, that on the stand ( 22 ) a bearing lever ( 24 ) which rotatably supports the other roller ( 14 ) and which can be pivoted relative to the stand ( 22 ) in order to bring the two rollers ( 14 , 16 ) closer to one another, and that the force generating means ( 26 ) on the bearing lever ( 24 ) attack. 9. The device according to claim 8, characterized in that the sensor means ( 36 ; 36 a; 36 b) comprise at least one sensor ( 36 ) which is attached to the bearing lever ( 24 ) or the stand ( 22 ). 10. The apparatus of claim 8 or 9, characterized in that the sensor means (36; 36 b; 36 a) comprise at least one sensor (36 b), wherein (a 14) arranged in a bearing region of one of the rollers. 11. The device according to claim 10, characterized in that the sensor ( 36 b) is attached to a bearing journal ( 48 a) of the roller ( 14 a) in question. 12. The device according to claim 10, characterized in that a bearing journal ( 48 a) of the relevant roller ( 14 a) surrounding roller bearing ( 52 a) is provided with the sensor. 13. The apparatus according to claim 12, characterized in that the sensor is integrated in the rolling bearing ( 52 a). 14. The apparatus according to claim 12, characterized in that the sensor is attached to an outer ring ( 56 a) of the rolling bearing ( 52 a). 15. The apparatus according to claim 10, characterized in that the sensor is attached to a bearing housing ( 50 a), in which a roller bearing ( 52 a) surrounding a bearing journal ( 48 a) of the relevant roller ( 14 a) is accommodated. 16. The device according to one of claims 8 to 15, characterized in that the sensor means ( 36 ; 36 a; 36 b) comprise at least one sensor which is accommodated in a separately produced sensor module ( 36 a), this sensor module ( 36 a ) between the stand or the bearing lever ( 24 a) and a bearing kit ( 46 a) for a journal ( 48 a) of the roller ( 14 a) held on the stand or the bearing lever ( 24 a) is installed. 17. Device according to one of claims 1 to 16, characterized in that the sensor means ( 36 ; 36 a; 36 b) for force sensing comprise at least one tension- and / or pressure-sensitive element, in particular a strain gauge. 18. Device according to one of claims 1 to 17, characterized by an on the sensor means ( 36 ; 36 a; 36 b) responsive and the force generating means ( 26 ) controlling electronic control unit ( 30 ), which for the controlled maintenance of a predetermined setpoint of the pressing force between the rollers ( 14 , 16 ) is set up. 19. The apparatus according to claim 18, characterized in that the force generating means ( 26 ) in the region of both axial ends of the roller pair ( 14 , 16 ) each comprise at least one independently controllable, in particular hydraulic power device ( 28 ) and the sensor means ( 36 ; 36 a; 36 b) are designed for independent detection of the pressing force in both axial end regions of the pair of rollers ( 14 , 16 ). 20. The apparatus according to claim 19, characterized in that the control unit ( 30 ) is set up to control the force devices ( 28 ) in such a way that an essentially constant line pressure between the rollers ( 14 , 16 , 16 ) is determined by the axial extension of the pair of rollers ( 14 , 16 ). 16 ) results. 21. Device according to one of claims 1 to 20, characterized in that the material web ( 10 ) is passed between the two rollers ( 14 , 16 ) and at least one of the rollers ( 14 , 16 ) for transferring the application medium to the material web ( 10 ) serves.