Papermaking machine

Abstract

Machine for a web having at least one marking device structured and arranged to apply at least two markings at a distance from one another in a longitudinal direction to the web. At least one measuring device is arranged downstream, relative to a web run direction, of the at least one marking device. The at least one measuring device is structured and arranged to measure the distance between the markings. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority under 35 U.S.C. .sctn.119 of German Patent Application No. 10 2004 018 522.0, filed on Apr. 14, 2004, the disclosure of which is expressly incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a machine for producing a paper, board, tissue or another fibrous web from a fibrous stock suspension or for finishing or further processing the fibrous web.

[0004] 2. Discussion of Background Information

[0005] Problems may occur to the web dimensions during the production, processing and finishing (or further treatment such as during a printing process) of fibrous webs. For example, a change in length of the web as a result of web tension or as a result of stretching of the web. These effects to the web dimensions may occur because of the pressure treatment, the thermal treatment or as a result of a changing moisture content. It is therefore necessary to measure the stretching of the web. WO 99/22067 discloses an example of a papermaking machine for producing a paper web from a fibrous stock suspension.

[0006] Accordingly, the prior art teaches measurements of this type are carried out indirectly by comparing the drive speeds within a machine or via an analysis of the winding hardness of a reel produced from the fibrous web in a winding machine. A method of this type has the disadvantage that it does not permit any information to be obtained about stretch within the production process. In particular, a change of this type occurs during the change from one machine to another machine in which the fibrous web is processed further "offline". For example, when the fibrous web is first wound onto a reel during its production from the fibrous stock suspension. The reel which is stored temporarily and cut into a plurality of rolls of a desired width is directed to slitting devices in a subsequent operation. It is possible, the fibrous web is stored on a reel that is coated with a medium in a coating machine at a later time.

[0007] When the stretch is measured conventionally, slippage of the fibrous web with respect to the surfaces of the driving rolls distorts the information from the drive signals. In determining the stretch of a material web from the winding hardness, additional factors that distort the result need to be taken into account. These factors which not only reproduce the "wound-in tensile stress", also arise as a result of air wound in, or profile fluctuations, etc., such that the winding hardness is not a sufficiently accurate measure of the stretch of a fibrous web.

SUMMARY OF THE INVENTION

[0008] The present invention provides a machine in which the stretch of the material web can be determined accurately.

[0009] According to the invention, a measuring device and at least one arrangement (or marking device) for applying at least two markings at a distance from one another in the longitudinal direction to the fibrous web is fitted in the machine for measuring the distance between the markings. In particular, a non-contact measuring device, arranged downstream of the arrangement in the web running direction of the fibrous web, is fitted in the machine for measuring the distance between the markings.

[0010] The distance measured with the measuring device between the markings, for example following one another, is subsequently compared with the known distance when setting the markings. In this manner, the stretch of the fibrous web is determined. It is possible during the comparison that further measurements, such as the speed of the fibrous web or the web tension at specific points or the like, can be taken into account.

[0011] Furthermore, it should be noted that the marking is not restricted to bar symbols. The marking can include a code which comprises further information. For example, such information may include absolute values of the fibrous web length at the marking, or the type of paper, etc. In this case, the code can be formed as a numeric code or as a bar code.

[0012] According to the invention, the measuring system can be integrated in a machine at various points and may be used for various process steps. For example, in a winding machine, the stretch of the material web in the process chain (through which the latter runs) can also be determine when arranged offline downstream of the machine for producing the fibrous web. It is also possible to determine the wound-in tensile stress according to the invention. Further, a determination of the residual ability to stretch the fibrous material before it breaks may be made, based on the measured stretch and the "stress" caused by this effect for the fibrous material (or paper). This dependence can be presented in a stress/strain graph. In connection with tensile measurements, statements relating to the modulus of elasticity of the fibrous material can be made. These measurements can be verified with a soft sensor for measuring strength properties in correlation with further data determined in a laboratory.

[0013] A soft sensor is understood to mean a software-based sensor in which raw measured data in the form of quality or process data are available during the production or finishing process. It is possible for measurements of quality parameters in the laboratory to be incorporated into the raw measured data. Further, the raw measured data can be combined into data sets which have all been determined simultaneously. Further still, it is possible to select specific laboratory or quality measurements as target data, which can be calculated from the other data used as input data directed to at least one soft sensor algorithm running in a computer-based operation and combining unit. Each data set containing measured data which relates approximately to the same inspection volume of web or raw material, in particular paper or paper furnish.

[0014] According to another feature of the invention, the origin of winding defects during the winding of the fibrous web to form a wound reel that can be analyzed. Further, the stretch measurements in conjunction with length measurements can determine a measure of the "true length" of the web wound up in a wound reel. Further still, markings on the fibrous web such as on its outer edge can also be used in making a determination of the measurements.

[0015] According to another feature of the invention, a provision is made for the arrangement to be arranged in a wire former or in a press section of the machine for producing the fibrous web. As a result, stretch of the fibrous web in the forming section or the press section could be determined with the method according to the invention.

[0016] According to another feature of the invention, there is at least one further measuring possibility for measuring the length of a section of the fibrous web in the machine. As a result, a marking applied to the fibrous web by the arrangement can be recalibrated, in order to achieve a correlation between the marking and further length measuring devices.

[0017] According to another feature of the invention, another possibility of measuring can be for non-contact measurements. For example, a rotary encoder, a trigger device, a measuring device fitted to a roll, in particular an encoder, or a device for measuring a drive signal.

[0018] According to another feature of the invention, the use of a comparison device for comparing the measured device measured by the measuring device and by the further measuring means. In particular, a control computer may also be used. The data obtained by the non-contact measurement, includes the measurement of the web length (via rotary encoders, triggers, etc. on rolls) and the measurement of the drive signals at various points in the production process of the fibrous web. Further, the data obtained by the non-contact measurement can be compared with the original marking information to make a determination of the web length.

[0019] Additionally, an evaluation unit can advantageously be used to evaluate the measured values obtained by the comparison device, in particular the control computer, relating to the stretch during the production of the fibrous web and to store or archive the data obtained.

[0020] The evaluation unit is advantageously connected to a further control computer, which is arranged in an additional process unit, in particular also operating offline in relation to the machine.

[0021] According to the invention, tension and stretch of the fibrous web are registered independently of each other, so that the stretch can be detected over the extensive course of a process.

[0022] The present invention is directed to a machine for a web comprising at least one marking device structured and arranged to apply at least two markings at a distance from one another in a longitudinal direction to the web. At least one measuring device is arranged downstream, relative to a web run direction, of the at least one marking device, that is structured and arranged to measure the distance between the markings.

[0023] In accordance with a feature of the invention, the machine is structured and arranged to produce a fibrous web from a fibrous stock suspension. The machine is structured and arranged for one of finishing or further processing said fibrous web. Further, the fibrous web is one of a paper, board, or tissue web.

[0024] The at least one measuring device is a non-contact measuring device. At least one marking device is arranged in one of a wire former or in a press section of the machine. Further, at least one other measuring device is structured and arranged to measure a length of a section of the web in the machine. Further still, at least one other measuring device comprises one of a non-contact measuring device, a rotary encoder, a trigger device, a measuring device fitted to a roll, an encoder, or a device for measuring a drive signal.

[0025] In accordance with a feature of the invention, a comparison device compares values measured by at least one measuring device and by at least one other measuring device. Further, the comparison device can be a control unit. Further still, an evaluation unit is used to evaluate the measured values and then compare them in the comparison device. The measured values correspond to a stretching of the web during production. Further, the evaluating unit stores the measured values. Further still, the evaluation unit can be either connected to a control unit or assigned to a process unit. The control unit is arranged in the process unit, which is arranged to operate offline from the machine. Further, at least one measuring device is arranged to measure values relating to web stretch in at least one subsequent offline process. The at least one subsequent offline process can be either calendering, coating, or winding.

[0026] In accordance with a feature of the invention, a process for a web comprises applying at least two markings on the web, which are separated in a longitudinal direction of the web, and measures a distance between the at least two markings. Further, the distance measuring occurs in a region of a press section of a web production device. Further still, the distance is measured without contacting the web and measures a length of a section of the web in the machine.

[0027] In accordance with a feature of the invention, compares the distance measured and the measured length of the web section. Further, the process includes evaluating and storing values for the measured distance and the measured length of the web section, which corresponds to a stretching of the web.

[0028] In accordance with a feature of the invention, a machine for a web comprising at least one arrangement for applying at least two markings at a distance from one another in a longitudinal direction to the web. Further, at least one measuring device is arranged downstream of at least one arrangement in a web running direction of the web, for measuring the distance between the markings. Further still, at least one control unit is used to control web stretching during the production of the web.

[0029] Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:

[0031] FIG. 1 shows a schematic drawing relating to the determination of stretch by using a section of a machine for producing a fibrous web and

[0032] FIG. 2 shows a papermaking machine having devices for determining the stretch of the paper web.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0033] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.

[0034] FIG. 1 shows a machine for producing or treating a fibrous web 1 comprises an arrangement of cylinders 2 to 8, over which or between which the fibrous web 1 is led. Between the cylinder 2 and the pair of cylinders 3, 4 there is an arrangement (or marking device) 9 for applying web edge markings to the fibrous web 1. Between the pair of cylinders 3, 4 and a group of cylinders comprising the cylinders 5 to 8, there is arranged a device 10 for non-contact speed measurement of the fibrous web 1.

[0035] According to the invention a unit 12 for measuring the tension exerted on the fibrous web 1 is fitted on a roll 11. A rotary encoder 14 is installed on a further roll 13.

[0036] The arrangement (or marking device) 9 and the measuring devices 10, 12 and 14 pass on their data to a control computer 15 (or control unit) that evaluates the data. In addition, a process unit 16 arranged offline from the machine is equipped with measuring units 17, 18, 19 to determine the distance between the markings on the fibrous web 1 and/or to calculate the rotational speed of rolls or cylinders, which pass their data to a control computer 20 (or control unit). The latter, like the control computer 15, is connected to an evaluation unit 21, in which the stretch of the fibrous web 1 in various method steps and at different points in the process of its production is followed back and archived.

[0037] FIG. 2 shows a papermaking machine equipped with for stretch measurements. In particular, a fibrous stock suspension from a head box 22 is fed to a gap between two wires 23 and 24 of a twin-wire former 25. On the radius of a forming roll 26, the wires 23, 24 run toward each other in a wedge shape and enclose the fibrous stock suspension between them. In this case, first dewatering of the fibrous stock suspension takes place and a fiber mat is formed, from which a paper web 27 is produced. An arrangement 28 for applying markings to the paper web 27, in particular to its web edge, is already present in the twin-wire former 25.

[0038] The twin-wire former 25 is followed by a press section 29. The press section 29 comprises, by way of example, as illustrated, three press locations 30, 31, 32. The first two press locations 30, 31 form a tandem NipcoFlex press section, in which in each case a roll 33, 34 interacts with a shoe press roll 35, 36. In the region of the press section 29, there is for example a first measuring device 37 for measuring the distance between the markings applied to the paper web 27 by the arrangement 28. However, it is noted that the first measuring device 37 can alternatively be positioned between the presses 31 and 32 or may be positioned before press 30. Moreover, it is contemplated that the arrangement 28 can be located in press section 29.

[0039] The press section 29 is followed by a drying section 40 having deflection rolls 38 and drying cylinders 39, in which the stretch of the paper web 27 is likewise determined by a measuring device 41.

[0040] After the drying section 40, the paper web 27 is led through between a shoe roll 42 and a roll 43 of a shoe calender 44 used as a calendering unit. The paper web 27 passes over deflection rolls into a film press 62 having two film rolls 45, 46.

[0041] On each of the two film rolls 45, 46, an application nozzle 47 or 48 applies a film of a coating color in excess, which is in each case doctored off by a metering bar 49, 50. As a result of the wetting of the paper web 27, its strength changes and the paper web 27 is stretched. Therefore, there can also be a measuring device 51 in the region downstream of the film press 62.

[0042] The paper web 27 is then led onward through a deflection element 52 operating with air pressure to a float drier 53, such that the paper web 27 is dried on both sides via thermal radiation or hot air and downstream of which a measuring device 54 for measuring the stretch of the paper web 27 is may be installed.

[0043] The paper web 27, which is now dried again, is led onward over further deflection rolls 55, 56 to a nozzle moistener 57, such that it is re-wetted again to a defined level of moisture and moisture gradient. Downstream of the nozzle moistener 57, the web 27 is calendered in a calender 58. The paper web 27 leaving the calender 58 is then wound up in a winding machine 59 to form a paper reel. The winding machine 59 for winding the paper web 27 may also be arranged offline from the machine for producing the paper web 27 from the fibrous stock suspension. Measuring devices 60 and 61 for measuring stretch are also arranged downstream of the nozzle moistener 57 and/or downstream of the calender 58.

[0044] Likewise, rotary encoders for measuring the circumferential speed of the associated rolls or cylinders can be built in, for example in rolls belonging to the film press 62 or the calender 58. In particular, rotary encoders would be able to determine the correlation between the circumferential speed and the stretch and the slippage of the paper web 27. All the data measured by the rotary encoders, the measuring devices 37, 41, 51, 60, 61 and by other devices for measuring the speeds of the paper web 27 and the rolls or cylinders are supplied to a control computer (FIG. 1).

[0045] It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.

Claims

What is claimed:

1. A machine for a web comprising: at least one marking device structured and arranged to apply at least two markings at a distance from one another in a longitudinal direction to the web; and at least one measuring device arranged downstream, relative to a web run direction, of said at least one marking device, structured and arranged to measure the distance between the markings.

2. The machine as claimed in claim 1, wherein the machine is structured and arranged to produce a fibrous web from a fibrous stock suspension.

3. The machine as claimed in claim 2, wherein the machine is structured and arranged for one of finishing or further processing said fibrous web.

4. The machine as claimed in claim 2, wherein the fibrous web is one of a paper, board, or tissue web.

5. The machine as claimed in claim 1, wherein said at least one measuring device is a non-contact measuring device.

6. The machine as claimed in claim 1, wherein said at least one marking device is arranged in one of a wire former or in a press section of the machine.

7. The machine as claimed in claim 1, further comprising at least one other measuring device structured and arranged to measure a length of a section of the web in the machine.

8. The machine as claimed in claim 7, wherein said at least one other measuring device comprises one of a non-contact measuring device, a rotary encoder, a trigger device, a measuring device fitted to a roll, an encoder, or a device for measuring a drive signal.

9. The machine as claimed in claim 1, further comprising a comparison device for comparing values measured by said at least one measuring device and by said at least one other measuring device.

10. The machine as claimed in claim 9, wherein said comparison device is a control unit.

11. The machine as claimed in claim 9, further comprising an evaluation unit to evaluate the measured values compared in said comparison device, wherein the measured values correspond to a stretching of the web during production.

12. The machine as claimed in claim 11, wherein said evaluating device stores the measured values.

13. The machine as claimed in claim 11, wherein said evaluation unit is one of connected to a control unit or assigned to a process unit.

14. The machine as claimed in claim 13, wherein said control unit is arranged in said process unit, which is arranged to operate offline from the machine.

15. The machine as claimed in claim 11, wherein said at least one measuring device is arranged to measure values relating to web stretch in at least one subsequent offline process.

16. The machine as claimed in claim 15, wherein said at least one subsequent offline process is one of calendering, coating, or winding.

17. A process for a web comprising: applying at least two markings on the web, which are separated in a longitudinal direction of the web; and measuring a distance between the at least two markings.

18. The process in accordance with claim 17, wherein the distance measuring occurs in a region of a press section of a web production device.

19. The process in accordance with claim 17, wherein the distance is measured without contacting the web.

20. The process in accordance with claim 17, further comprising measuring a length of a section of the web in the machine.

21. The process in accordance with claim 20, further comprising comparing the distance measured and the measured length of the web section.

22. The process in accordance with claim 20, further comprising evaluating and storing values for the measured distance and the measured length of the web section, which corresponds to a stretching of the web.

23. A machine for a web comprising: at least one arrangement for applying at least two markings at a distance from one another in a longitudinal direction to the web; at least one measuring device arranged downstream of said at least one arrangement in a web running direction of the web for measuring the distance between the markings; and at least one control unit to control web stretching during the production of the web.