EP2678652A1

EP2678652A1 - Paper machine roller having fibre bragg sensors

Info

Publication number: EP2678652A1
Application number: EP12706227.1A
Authority: EP
Inventors: Antje Berendes; Martin Breineder; Matthias Schmitt; Yang SHIEH
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2011-02-25
Filing date: 2012-02-20
Publication date: 2014-01-01
Also published as: CA2830088A1; WO2012113747A1; CN103403513B; CN103403513A; US20130345035A1

Abstract

The invention relates to a roller (1) for use in paper machines, having a roller core (11), a roller covering (12) surrounding the roller core (11) and at least one optical waveguide (21) having a plurality of fibre Bragg gratings (22). The at least one optical waveguide (21) is either arranged between the roller core (11) and the roller covering (12) or embedded in the roller covering (12). Sections of the at least one optical waveguide (21) which each contain a fibre Bragg grating (22) alternate with sections of the at least one optical waveguide (21) which are free of fibre Bragg gratings (22) in the longitudinal direction of the optical waveguide. Sections of the at least one optical waveguide (21) which each contain a fibre Bragg grating (22) also enclose an angle with a circumferential direction to the roller (1) of less than 80° and in particular less than 60° and further in particular less than 45°.

Description

PAPER MACHINE ROLL WITH FIBER BRAGG SENSORS

The invention relates to rolls for machines for industrial papermaking, which have fiber Bragg sensors for detecting a pressure acting on the roller. In order to form a nonwoven web, in industrial papermaking, first a suspension is applied to a carrier, such as a carrier. B. applied and dewatered. Dewatering is continued following formation in subsequent sections of the paper machine until finally a self-supporting nonwoven web is produced. During the dewatering process, the non-self-supporting nonwoven web is usually transferred to other carriers, such as felts or other sieves. In both the forming and wet ends of a paper machine, the nonwoven web is guided by the support supporting it through a series of nips. The term nip refers to the region between two cooperating rolls or between a roll and the so-called shoes pressing against them, in which the nonwoven fabric is pressed or pressurized. The pressure profile which forms in the nips when passing through the nonwoven web has a significant influence on the efficiency with which the nonwoven web is dewatered and smoothed. With uneven pressure distribution in the nip, the nonwoven web has an uneven moisture profile or only poor smoothing. Paper manufacturers are therefore anxious to monitor the pressure profiles in the nip areas.

The rolls used usually have a roll core which receives the load on. Depending on in which phase of the production process the nonwoven fabric is processed, the surfaces of the rolls which come into contact with it must have different properties. Therefore, the rollers in the region of the peripheral surface of the roller, which comes into contact with the nonwoven fabric, are usually provided with a so-called roll cover having the respective desired properties. In this case, the roll cover can be constructed in multiple layers. The directly on the roll core adjacent and the connection between the roll core and roll cover producing layer is often referred to as a "base layer".

Sensors can be used to monitor the pressure profile in the nip during operation. Usually, the sensors are arranged on the outer circumferential surface of the roll core or within the roll cover. Radial forces acting on the roll geometry are typically detected using piezoelectric or electromechanical sensors. Both types of sensors generate an electrical signal that is representative of their deformation under the respective pressure conditions. Since the rotational speed of the rolls is very high in modern paper machines, the sensor signal values are preferably transmitted by radio to external processing devices. Instead of working with electrical means sensors and fiber optic sensors can be used in which the optical properties of an optical waveguide (such as a glass fiber) are changed by the transmitted to the optical waveguide deformation stress. International patent application PCT / EP2008 / 08050 describes fiber optic sensors for use in roll covers for paper machines which use fiber Bragg gratings inscribed in glass fibers as sensor elements. Fiber Bragg gratings are arranged in optical waveguide optical interference filter, which are written for example by means of a laser in the optical waveguide. Wavelengths that lie within the given filter bandwidth by λ _Β are reflected. Reference is made in full to the disclosure of WO 2010/034321 A1 with regard to the mode of operation of fiber Bragg gratings.

The present invention relates to a roller for use in paper machines, which allows a determination of a pressure acting on the roller and its course with respect to the roller geometry (for example, in a nip) in a reliable manner and yet inexpensive to produce in a simple manner. Furthermore, the present invention relates to a method for producing a corresponding roller.

The above object is achieved according to embodiments by the Combination of the features of the independent claims solved. Preferred developments can be found in the subclaims.

According to a first aspect of the present invention, there is provided a roll for use in papermaking machines comprising a roll core, a roll cover surrounding the roll core, and at least one optical waveguide having a plurality of fiber Bragg gratings. The roll core can for example be made of metal (in particular steel) or plastic (in particular carbon fiber reinforced plastic CFK or a fiber-plastic composite FKV) and be solid or hollow. Next, the roll core can be made either in one piece or in several pieces. The roll cover may for example comprise plastic or be formed therefrom. The at least one optical waveguide can be arranged either between the roll core and roll cover or embedded in the roll cover. If the at least one optical waveguide is embedded in the roll cover, it can optionally be embedded in a layer of the roll cover or arranged between two layers of the roll cover. In this document, the layer often referred to as the "base layer", which immediately adjoins the roll core and establishes the connection between roll core and roll cover, is understood as a layer of the roll cover, even if it is formed from the same material as the roll core. In the longitudinal direction of the optical waveguide, portions of the at least one optical waveguide, each containing a fiber Bragg grating (hereinafter fiber Bragg grating sections), alternate with portions of the at least one optical waveguide which are free of a fiber Bragg grating (hereinafter fiber Bragg lattice-free sections). Fiber Bragg grating sections enclose with a circumferential direction to the roller at an angle of less than 80 ° and in particular less than 60 ° and more particularly less than 45 °. According to one embodiment, the at least one optical waveguide in the fiber Bragg grating sections is connected non-positively to the adjacent roller core and / or roller cover. The fiber Bragg grating sections and the adjacent roller core and / or roller cover then directly adjoin and contact each other.

In such orientation fiber Bragg grating sections of the Optical waveguide performs a radial compressive load on the roller to a tensile load of the optical waveguide in this section. The cause is considered to be caused by the pressure load temporary and reversible displacement of the roll cover in the circumferential direction. Depending on this tensile loading, the wavelength range of the radiation reflected by the fiber Bragg grating shifts. The reason is a shift in the distance between refractive index transitions in the optical waveguide. This shift of the wavelength range thus allows conclusions about the pressure load of the roller.

It is harmless if individual fiber Bragg grating sections with a circumferential direction to the roller enclose an angle greater than 80 °, as long as more than 50% of the sections and in particular more than 70% of the sections and more particularly more than 90% of the sections one Include angle of less than 80 ° and in particular less than 60 ° and more particularly less than 45 °. Fiber Bragg grating sections which enclose an angle of greater than 80 ° with the circumferential direction to the roller, enclose an angle of less than 10 ° with the axial direction of the roller and thus extend almost parallel to the axial direction. Such oriented fiber Bragg grating sections are subject to a low (or even in the case of an axial orientation) tensile load under pressure of the roller, so that a determination of the pressure is difficult or impossible. Between the fiber Bragg grating sections lying fiber Bragg grating-free sections can be arbitrary. Overall, the optical waveguide can be arranged wave-like or meandering.

According to a further independent aspect of the invention, there is provided a roller for use in paper machines, comprising a roller core and a roller cover surrounding the roller core, and at least one optical fiber having a plurality of fiber Bragg gratings, the at least one optical fiber extending therebetween between the roller core and the roller cover arranged or embedded in the roll cover longitudinal extent extends on a concentric with the axis of rotation of the roller cylindrical surface. In other words, the optical waveguide extends on a concentric with the axis of rotation of the roller cylindrical surface, which is formed either by the interface between the roll core and roll cover or is disposed within the roll cover. Furthermore, fiber Bragg grating sections of the at least one optical waveguide alternate with fiber Bragg grating-free sections of the at least one optical waveguide in the longitudinal direction of the optical waveguide. In the roll according to the invention according to the second aspect of the invention is further provided that at least some of the roll core and roll cover or embedded in the roll cover fiber Bragg grid-free sections on the cylindrical surface are curved. Due to the curved course of the fiber Bragg grating-free sections in a single radial height, the fiber Bragg grating sections can be oriented almost arbitrarily, in particular it is possible in this case to orient the fiber Bragg grating sections, that these include with the circumferential direction to the roller an angle of less than 80 ° and in particular less than 60 ° and more particularly less than 45 °.

Furthermore, the distances between the fiber Bragg gratings can be varied over a wide range by the curved course of the fiber Bragg gratings-free sections and thus according to the requirements of the roller, for example. In the axial direction of the roller, the distance Fiber Bragg grating in the roller and thus the distance between the sensors varies with each other and thus the local resolution can be adjusted.

Furthermore, it is conceivable that different fiber Bragg grating-free sections of the at least one optical waveguide have a length that is different by a maximum of 30%, preferably a maximum of 10%. It is particularly preferred if the plurality of fiber Bragg grating-free sections of the at least one optical waveguide have the same length. As a result, the optical waveguide for almost any roller-regardless of the length and the circumference of the roller- be assembled and the distance between the fiber Bragg gratings in the roll cover from each other, adjusted by the curved course of the fiber Bragg grating-free sections become. In order to avoid excessive attenuation of the light in the curved course of the at least one optical waveguide, it makes sense if the optical waveguide is not too curved. This is particularly useful because in the confined space of a roller, for example. For a paper, board or Tissuemaschine, only relatively faint light sources can be used, which have no high heat and therefore also require no complex and space consuming cooling devices. A particularly preferred embodiment of the invention, which can also be regarded as an independent aspect of the invention, therefore provides that the at least one optical waveguide is curved at least in sections along its longitudinal extent embedded between the roll core and the roll cover or embedded in the roll cover, and the radius of curvature of the curved course of the optical waveguide 2cm or larger, preferably 3cm or larger, more preferably 5cm or larger.

Preferably, at least some, in particular all embedded between roll clamps and roll cover or embedded in the roll cover fiber Bragg grating-free sections of the at least one optical waveguide are each curved in only one direction. In the case of two fiber Bragg grating-free sections between which a fiber Bragg grating section is arranged, this can mean, for example, that one of the two Bragg grating-free sections has a positive curvature and the other of the two Bragg lattice-free sections has a negative curvature or vice versa. Accordingly, successive fiber Bragg grating-free sections of the at least one optical waveguide between which a fiber Bragg grating section of the at least one optical waveguide is arranged are therefore curved in mutually different directions. The at least one optical waveguide can preferably be embedded at least along its length in the roll cover or between the roll core and roll cover, have a core and a sheath surrounding the core or be formed therefrom. In this case, the sheath in the region of the fiber Bragg grating sections is preferably either directly with the roller core and the roll cover or directly in contact with the roll cover. Thus, according to this embodiment, the fiber Bragg grating portions of the optical waveguide, other than those disclosed in WO02 / 034321, are directly applied with the force acting on the roll cover without an intermediate element -here referred to as a "stud element." Surprisingly, attempts have been made Applicants have found that the use of the intermediate elements described in WO2010 / 034321 is not indispensable in order to achieve sufficient signal sensitivity.When subjected to pressure loading, the roll is subject to a maximum tensile load between the roll core and roll cover or fiber Bragg grating sections arranged in the roll cover In this case, the fiber Bragg grating sections have the greatest signal sensitivity. Generally, it can be noted that the signal sensitivity decreases with decreasing angle which the fiber Bragg gratings have Sections of the optical fiber with the circumferential direction of the roller becomes larger and, as already stated above, when aligned parallel to the axial direction of the roller is zero.

In order to achieve a high signal sensitivity, a preferred embodiment of the invention provides that the fiber Bragg grating sections with a circumferential direction to the roller at an angle of less than 30 ° and in particular less than 20 ° and further include less than 10 °.

Depending on the arrangement of the optical waveguide on the roll core or in the roll cover, of the materials used for the roll core and the roll cover, of the diameter of the roll and of the pressures occurring, for example, in soft roll covers the risk that the tensile load on the optical waveguide becomes too large and thus leads to irreversible damage to the optical waveguide. For some applications, it may therefore be useful if the fiber Bragg grating sections include an angle of greater than 10 ° and in particular greater than 20 ° and more particularly greater than 30 ° with a circumferential direction to the roller. In such an inclination occurs on the one hand under pressure load of the roller regularly sufficient tensile load of the optical waveguide, and at the same time prevents irreversible damage to the optical waveguide as a result of excessive tensile stress. According to one embodiment, fiber Bragg grating sections are arranged adjacent to the roller in the axial direction. In this case, fiber Bragg grating sections can be arranged in an area extending in the axial direction over the entire length of the roller, the extent of which in the circumferential direction is less than 15 cm and in particular less than 5 cm and more particularly less than 1 cm. This allows a determination of the pressure curve in the axial direction of the roller at a certain angle of rotation of the roller. In one embodiment, fiber Bragg grating sections are spaced a constant distance in the axial direction of the roller. This allows a uniform determination of the pressure curve in the axial direction of the roller. This constant distance can be measured, for example, from the center of the respective fiber Bragg grating.

According to an alternative embodiment, fiber Bragg grating sections are spaced in the axial direction of the roller in a first region by a first distance and in at least a second region by a second distance, wherein in particular the second distance by at least 30% and in particular by at least 60%, and more particularly at least 90% greater than the first distance. This constant distance can be measured, for example, from the center of the respective fiber Bragg grating. Such an arrangement allows a determination of the pressure curve in the axial direction of the roller, in which the density of the fiber Bragg gratings and thus the obtained pressure measurements in areas of interest in the axial direction of the roller (for example in the vicinity of the roller bearings) greater than in other areas in the axial direction of the roller (for example in the roller center). If a plurality of second regions are provided, the second distances in the second regions may be the same (and in particular the same in pairs) or different. A constant change of the distances is possible.

According to one embodiment, the roller has more than one optical waveguide, and adjacent fiber Bragg grating sections of different optical waveguides are arranged in a circumferentially extending over the entire circumference of the roller and thus a total annular area whose extent in the axial direction of the roller less than 10 cm and in particular less than 3 cm and more particularly less than 1 cm. The above condition need not be met by all adjacent sections of different optical fibers. Rather, it is sufficient if this condition is met in pairs by individual fiber Bragg grating sections of different optical fibers. Thus, the (immediately) adjacent fiber Bragg gratings of different optical waveguides in this embodiment are arranged along strips which surround the roller in the circumferential direction in a circular manner. This allows a determination of the pressure load at different angles of rotation of the roller.

Preferably, in this context, adjacent fiber Bragg grating sections of different optical waveguides, which are arranged in the region whose extent in the axial direction of the roller is less than 10 cm and in particular less than 3 cm and more particularly less than 1 cm, in the circumferential direction of the roller 45 ° or more, in particular 90 ° or more offset from one another.

According to an alternative embodiment, fiber Bragg grating sections are arranged adjacent in the circumferential direction of the roller. In this case, fiber Bragg grating sections can be arranged in a region extending in the circumferential direction over the entire circumference of the roll, the extent of which in the axial direction of the roll is less than 15 cm and in particular less than 5 cm and more particularly less than 1 cm. This allows a determination of the pressure load of the roller at different angles of rotation of the roller.

According to one embodiment, the roller has more than one optical waveguide, and adjacent fiber Bragg grating sections of different optical waveguides are arranged in an area extending in the axial direction over the entire length of the roller, whose extent in the circumferential direction of the roller is less than 15 cm and in particular less than 5 cm and more particularly less than 1 cm. This allows a determination of the compressive load in the axial direction of the roller at different angles of rotation of the roller.

According to one embodiment, in the longitudinal direction of the optical waveguide spaced fiber Bragg gratings of the same optical fiber configured to reflect light of different wavelengths. This allows an assignment of a measurement signal to the respective fiber Bragg grating of the same optical waveguide when the fiber Bragg gratings of the same optical waveguide are simultaneously loaded with tension. Thus, a spatial resolution is possible even if the fiber Bragg gratings of the same optical waveguide are arranged in the axial direction of the roller in a narrow, simultaneously subjected to a pressure load area. According to one embodiment, in the longitudinal direction of the optical waveguide spaced fiber Bragg gratings of the same optical waveguide are formed to reflect light of the same wavelength. Such optical waveguides are particularly easy to manufacture. However, a spatial resolution is only possible if the fiber Bragg gratings of the same optical waveguide are arranged offset in the circumferential direction of the roller to each other, and thus subject at different times of a pressure load.

According to one embodiment, fiber Bragg grating sections are arranged along a helical curve described on the surface of the roller, wherein a deviation from the helical curve both in the axial direction of the roller and in the circumferential direction of the roller is less than 15 cm and in particular less than 5 cm and more particularly less than 1 cm. This allows a pressure measurement in different axial areas of the roller at different angles of rotation of the roller.

According to one embodiment, one end of the at least one optical waveguide is led out of the roll cover. According to a further embodiment, both ends of the at least one optical waveguide are led out of the roll cover. According to an alternative embodiment, a light source and a light detector are arranged in the roller, which are connected to the at least one optical waveguide and configured to perform measurements with respect to the fiber Bragg gratings of the at least one optical waveguide. The light detector may be connected to a transmitter to deliver acquired measurement data via an air interface to the outside of the roller. Further, in the roll, a coil may be arranged in which from outside the roll by induction Current flow can be stimulated to supply the components contained in the roller with energy.

According to one embodiment, the roll cover has a plurality of layers, and the at least one optical waveguide is arranged between two layers of the roll cover. According to an alternative embodiment, the roll cover has a plurality of layers, and the at least one optical waveguide is embedded in and surrounded by one of the plurality of layers. This allows a simple and secure attachment of the at least one optical waveguide. Furthermore, the optical waveguide is thus well protected against damage.

According to one embodiment, the at least one optical waveguide is embedded in epoxy resin. Epoxy resin allows a good switching of acting on the roller pressure forces on the at least one optical waveguide.

According to a further independent aspect of the invention, a method for producing a roll for use in papermaking machines is proposed with the following steps:

Providing a roll core with or without a roll cover layer,

Providing at least one optical waveguide with a plurality of fiber Bragg gratings, wherein fiber Bragg grating sections alternate with fiber Bragg gratings free sections in the longitudinal direction of the optical waveguide,

Fixing the fiber Bragg grating sections on the roll core or the roll cover layer so that the sections with a circumferential direction to the

Include roller at an angle of less than 45 ° and in particular less than 20 ° and more particularly less than 10 ° and

- Applying at least one further roll cover layer, which covers the at least one optical waveguide.

It is therefore sufficient first to fix fiber Bragg grating sections, so that fiber Bragg grating-free sections can initially be arbitrarily guided. However, the minimum permissible bending radii of the optical fibers used should be taken into account. As a result, the optical fibers can be quickly, easily and inexpensively integrated into the rollers. Fixing the fiber Bragg grating sections to the roller core or the roll cover layer can permanently, for example, with epoxy resin or releasably, for example, with adhesive tape done.

Providing a roll core having an axis of rotation with or without a roll cover layer, wherein the roll core or the roll reference layer provides a cylindrical surface concentric with the axis of rotation,

- Fixing the optical waveguide to the cylindrical surface so that the fiber Bragg lattice-free sections on the cylindrical surface are at least partially curved and

According to an embodiment of the method, prior to the step of fixing the fiber Bragg grating sections, a step of attaching a mark to the roller core or roller cover layer is made, which mark identifies the points or areas where a pressure measurement is to be made. This marking can also take place, for example, in the form of a groove into which the optical waveguide is to be inserted. This makes it possible to increase the accuracy of the arrangement of the fiber Bragg grating sections.

According to a further embodiment of the method, prior to the step of applying at least one reference layer, a step of fixing the fiber Bragg grating-free sections to the roll core or the roll cover layer takes place. In this way, it is ensured that the at least one optical waveguide bears against the entire surface of the roll core or the roll cover layer. If a releasable attachment for fixing the fiber Bragg grating sections to the roll core or roll cover layer is used, additionally detaching this releasable attachment and replacement by permanent attachment may be provided. In the following, exemplary embodiments of the invention are explained in more detail with reference to figures. In the figures, the same or similar elements are denoted by the same or similar reference numerals. Showing:

Figure 1 shows schematically a perspective view of a roller according to a first embodiment in which a part of the cover is removed and exposed optical fibers with fiber Bragg gratings;

FIG. 1 a shows a schematic enlarged view of the roll cover of the illustration of FIG. 1; FIG. 2 schematically shows a perspective view of a roller according to a second embodiment, wherein a part of the cover is removed and optical fibers are exposed with fiber Bragg gratings; FIG. 3 shows schematically a perspective view of a roller according to a third embodiment, in which a part of the cover is removed and optical fibers are exposed with fiber Bragg gratings;

Figure 4 shows schematically a perspective view of a roller according to a fourth embodiment, in which a part of the cover is removed and exposed optical fibers with fiber Bragg gratings; and

Figure 5 schematically shows a perspective view of a roller according to a fifth embodiment, in which a part of the cover is removed and exposed optical fibers with fiber Bragg gratings.

FIG. 1 schematically shows a perspective view of a roll 1 according to a first embodiment.

The roller 1 has an axis of rotation 44 providing roll core 1 1 and a roll cover 12 surrounding this. In this embodiment, the roller core 1 1 made of steel and the roller cover 12 made of plastic. In order to allow a good adhesion between the roll cover 12 and the roll core 1 1, between the roll cover 12 and the roll core 1 1 a known to those skilled in the "base layer" connecting layer is provided, which is not shown in the figure specifically.

A Teilbereicht the roll cover 12 is exposed in the figure 1 and gives the view of an optical waveguide 21 with multiple fiber Bragg gratings 22 free. The individual fiber Bragg gratings 22 of the optical waveguide 21 are designed to reflect light of different wavelengths.

As can be seen from the illustration of FIGS. 1 and 1a, the optical waveguide 21 has fiber Bragg grating sections 22 as well as fiber Bragg gratings-free sections 43 ^' , 43 ^" , wherein the fiber Bragg gratings Sections 22 and the fiber Bragg grating-free sections 43 ^', 43 ^" in the longitudinal direction of the optical waveguide 21 alternate.

The optical waveguide 21 is arranged meander-shaped in the roll cover 1 1, and extends in the axial direction of the roller over the entire width of the roll cover 12 sections of the optical waveguide 21, each containing a fiber Bragg grating 22 (hereinafter fiber Bragg grating Sections 22) are arranged so that these sections each enclose an angle of approximately 0 ° with a circumferential direction to the roller 1. In this case, "approximately 0 °" means that deviations from 0 ° can be tolerated by a maximum of 15 ° and preferably a maximum of 10 °.

In this first embodiment, adjacent to an extension of the optical waveguide 21 adjacent fiber Bragg grating sections 22 in the axial direction of the roller 1 adjacent in a region 3, whose extension in the circumferential direction of the roller core 1 1 is exactly 1 cm. Thus, the fiber Bragg grating sections 22 arranged adjacent in the axial direction may have a maximum offset of 1 cm in the circumferential direction. The distance between the fiber Bragg grating sections 22 adjacent in the axial direction of the roller is chosen to be constant.

Due to this arrangement of the fiber Bragg grating sections 22, a pressure load on the roller cover 12 leads to a (slight) elongation of the optical waveguide 21 with the fiber Bragg gratings and thus to a change in the wavelength of the fiber Bragg grating. Lattices reflected light. In this way, it is possible to measure a pressure load on the roller along a line extending in the axial direction of the roller 1 line.

In the embodiment shown, both ends 23 and 24 of the optical waveguide are guided to the outside in order to be connected to a measuring device, not shown in FIG. FIG. 1 a shows a schematic enlarged view of the roll cover 12 of the illustration of FIG. 1.

The roll cover 12 has an inner cylindrical circumferential surface 12i in the radial direction of the roll 1 and a cylindrical outer surface 12a which is outer in the radial direction of the roll 1, the latter providing the upper side of the roll cover which can be brought into contact with a material web or covering. The two cylindrical lateral surfaces 12i and 12a are arranged concentrically to the axis of rotation 44.

Within the roller cover 12 there is a cylindrical surface 12k concentric with the axis of rotation 44, on which the at least one optical waveguide 21 is arranged and on which the fiber Bragg grating-free sections 43 ^' , 43 ^"of the optical waveguide 21 extend in a curved manner In this case, for example, 12k may be formed by the radially outer surface area of a radially inner roll reference layer 12 ^' on which the optical waveguide 21 is arranged and which in turn is covered by a radially outer roll reference layer 12 ^" , so that as a result the at least one optical waveguide 21 enters the Roll cover 12 is embedded.

It should be noted that the radius of curvature of the curved course of the optical waveguide 21 is 2 cm or larger. Further, it will be seen that each fiber Bragg grating-free section 43 ^' , 43 ^" is curved in only a single direction of curvature and that successive fiber Bragg grating-free sections 43 ^' , 43 ^" , between which a fiber Bragg grid portion 22 is arranged, are curved in mutually different directions of curvature. Thus, for example, the section 43 ^' is curved in the opposite direction as the section 43 ^" .

Furthermore, all embedded in the roll cover 12 fiber Bragg gratings free sections 43 have the same length.

2 shows a second embodiment of a roll 1 'in a schematic perspective view. Since this embodiment is very similar to the first embodiment described above, only differences will be discussed and otherwise referred to the first embodiment.

The second embodiment shown in FIG. 2 differs from the first embodiment described above in particular in that a second optical waveguide 21 'with fiber Bragg grating sections 22' is provided, which extends in the circumferential direction to the first optical waveguide 21 with the fiber optic cable. Bragg grating sections 22 is arranged offset. This second optical waveguide 21 'is accessible from outside via a connection 23'.

In this second embodiment, the second ends of the optical waveguides 21, 21 'are not led to the outside.

The fiber Bragg grating sections 22 'of the second optical waveguide 21' are arranged in the circumferential direction of the roller offset below the fiber Bragg grating sections 22 of the first optical waveguide 21, that arranged in the circumferential direction of the calf circumference adjacent arranged fiber Bragg gratings -Abschnitte 22, 22 'in the axial direction of the roller 1' are offset by less than 3 cm. In the circumferential direction, adjacent fiber Bragg grating sections 22, 22 'lie on a narrow ring surrounding the roller in the circumferential direction. In the axial direction, the fiber Bragg grating sections 22, 22 'of each optical waveguide 21, 21' are as described in the first embodiment arranged.

Such an arrangement of the optical waveguides 21, 21 'and fiber Bragg grating sections 22, 22' allows measuring a pressure distribution in the axial direction of the roller at different angles of rotation of the roller.

A perspective view of a roller 1 "according to a third embodiment is shown schematically in Figure 3. Since this embodiment is very similar to the first and second embodiments described above, only differences will be discussed and otherwise referred to the first and second embodiments.

The third embodiment shown in FIG. 3 differs from the first and second embodiments described above in that, instead of a roll core 1 1 made of solid material, a roll core 1 1 'made of carbon fiber reinforced plastic CFRP is used. Inside the tube is a measuring device comprising a light source and a light detector for emitting light into the optical waveguide 21 "and detecting the light reflected from fiber Bragg gratings of the optical waveguide 21", a microprocessor for obtaining a measurement result from the values output by the light detector and a transmitter for outputting a measurement result via an air interface to the outside. The energy required is supplied to the measuring device during rotation of the roller 1 "by inductive means.

Further, the third embodiment differs from the first embodiment in the arrangement of the fiber Bragg grating sections 22 ". In the third embodiment, the fiber Bragg grating sections 22" in the axial direction of the platen 1 "are pairwise either one in the embodiment shown, the second distance 42 is twice the first distance 41. The arrangement of the fiber Bragg grating sections 22 'in this embodiment is such that the density of the fiber -Bragg grid sections at the ends of the roll 1 "and thus higher in the region of the bearing, as in the center of the roll 1" .This allows the measurement of compressive forces on the roll in particularly interesting areas. On the back side of the roll 1 "shown in FIG. 3, a second optical waveguide with fiber Bragg gratings is provided, which is arranged with respect to the first optical waveguide 21 and its fiber Bragg grating sections 22" as described in the second embodiment ,

A fourth embodiment of a roll 1 "'is shown schematically in perspective view in Figure 4. Since this embodiment is very similar to the first one with the third embodiment described above, only differences will be discussed and otherwise referred to the previous embodiments.

In the fourth embodiment, the optical waveguides 21, 21 'are arranged with the fiber Bragg grating sections 22, 22' such that the individual optical waveguides 21, 21 'are sandwiched between two layers of the roller cover 12 (the individual layers are not specifically shown). Thus, along an extension of the optical waveguide 21, adjacent fiber Bragg grating sections 22 of the same optical waveguide 21 are arranged adjacent to one another in the circumferential direction of the roller along an extension of the optical waveguide 21, a distance 5 between two adjacent fiber optic waveguides 21 being arranged adjacent to each other. The fiber Bragg grating sections 22, 22 'of each of the same optical waveguides 21, 21' lie in a circumferential direction relative to the axial direction of the roller 1 "' the entire roller circumference extending portion 6, whose extension in the axial direction of the roller 1 5 cm.

Axially adjacent fiber Bragg grating sections 22, 22 'of different optical waveguides 21, 21' in the present embodiment are spaced a constant distance and arranged so that their placement in the circumferential direction of the roller is offset by less than 1 cm ,

In this fourth embodiment, the fiber Bragg gratings of the same optical waveguide 21, 21 'are each designed to reflect light of the same wavelength. With knowledge of the angular position of the roller 1 "'allows such an arrangement of the optical waveguides 21, 21' and fiber Bragg gratings detecting the Pressure distribution in the axial direction of the roll 1 "'at different rotation angles of the roll As in the third embodiment, the roll core 1 1' in the fourth embodiment is hollow and receives a measuring device which is connected to the optical waveguides 21, 21 '.

FIG. 5 schematically shows a perspective view of a roll 1 "" according to a fifth embodiment. Also in this embodiment, a part of a massive roll core 1 1 made of fiber-plastic composite FKV surrounding roll cover 12 is exposed and gives the view of several, embedded in a "base layer" of epoxy resin optical waveguides 21, 21 'with fiber Bragg Grid sections 22, 22 'free.

In this embodiment, both ends 23, 23 ', 24' of the optical waveguides 21, 21 'are each guided to the outside. The fiber Bragg grating sections 22, 22 'of the individual optical waveguides 21, 21' are each arranged according to this embodiment along a helical curve which completely and partially sweeps over the roller in the axial direction and in the circumferential direction. Again, the arrangement of the fiber Bragg grating adjacent optical waveguides 21, 21 'so that in the circumferential direction adjacent fiber Bragg gratings have no or only a small offset in the axial direction of the roller.

Although in FIGS. 1 to 5 the fiber Bragg grating sections each enclose an angle of approximately 0 ° with the circumferential direction of the roller, the present invention is not limited thereto. Rather, it is sufficient if the angle is less than 80 °, in particular less than 60 ° and more particularly less than 40 °. The provision of a certain angle of in particular greater than 10 ° and in particular greater than 20 ° and more particularly greater than 30 ° may even be necessary at very high pressures and / or the embedding of the at least one optical waveguide in a relatively soft roll cover to excessive To avoid tensile load of at least one optical waveguide. For example, the fiber Bragg grating portions of the circumferential direction of the roll may include the following angular ranges:

10 <<80 20 <<80 30 <<80

10 <<60 20 <<60 30 <<60

10 <<40 20 <<40 30 <<40

A method of manufacturing a roll for use with paper machines will be briefly described below. Since the process is linear, the creation of a figure has been omitted.

In a first step, a roll core is provided. This may for example consist of metal or plastic, and be solid or hollow. This may comprise a roll cover layer such as a "base layer".

Furthermore, at least one optical waveguide with a plurality of fiber Bragg gratings is provided, wherein sections of the at least one optical waveguide, which each contain a fiber Bragg grating, with sections of the at least one optical waveguide which are free of a fiber Bragg grating, alternate in the longitudinal direction of the optical waveguide.

Subsequently, a marking is applied to the roll core or the roll reference layer, which identifies areas where a pressure measurement is to take place. This marking can be applied for example by color or in the form of a groove in the roll core or roll cover can be introduced, which allows the inclusion of at least one optical waveguide. However, the step of applying a mark is only optional.

Then, fixing of sections of the at least one optical waveguide is carried out, which sections each include a fiber Bragg grating, so that the sections with a circumferential direction to the roller at an angle of less than 80 ° and in particular less than 60 ° and further include less than 45 °. The fixation can, for example, releasably by means of a Adhesive tape done, making corrections are easily possible.

Subsequently, the remaining portions of the at least one optical waveguide, which are free of fiber Bragg gratings, permanently fixed, for example by means of epoxy resin on the roll core or by means of a suitable adhesive to the roll reference layer. In this case, these sections, which are free of fiber Bragg gratings, between the sections of the optical waveguide, each having a fiber Bragg grating, form any loops.

Subsequently, the detachable fixing of the sections of the at least one optical waveguide, each containing a fiber Bragg grating, removed and these sections permanently fixed, for example by means of epoxy resin on the roll core or by means of a suitable adhesive to the roll reference layer before at least one further roll reference layer is applied ,

Instead of the above releasable specification of the sections of the at least one optical waveguide, which sections each contain a fiber Bragg grating, they can also be permanently connected to the roller or the roller reference layer. The step of removing the detachable connection can then be omitted.

It is emphasized that the preferred embodiments described above with reference to Figures 1 to 5 are merely exemplary and not intended to limit the scope of protection defined by the claims.

Claims

claims

Roller (1) for use in paper machines, comprising:

a roller core (11);

a roller cover (12) surrounding the roller core (11); and at least one optical fiber (21) having a plurality of fiber Bragg gratings

(22);

wherein the at least one optical waveguide (21) either between the roller core (1 1) and roll cover (12) arranged or embedded in the roll cover (12);

wherein portions of the at least one optical waveguide (21), each containing a fiber Bragg grating (22), with portions (43 ^' , 43 ^" ) of the at least one optical waveguide (21) which is free of a fiber Bragg grating (22), alternate in the longitudinal direction of the optical waveguide, and

wherein portions of the at least one optical waveguide (21), each containing a fiber Bragg grating (22), with a circumferential direction to the roller (1) an angle of less than 80 ° and in particular less than 60 ° and more particularly less than 45 °.

Roller (1) for use in paper machines, in particular according to claim 1, comprising:

a roller core (1 1) providing an axis of rotation (44) of the roller (1);

(22);

wherein the at least one optical waveguide (21) disposed either between the roller core (1 1) and roller cover (12) or in the Roll cover (12) is embedded; wherein the at least one optical waveguide (21) along its between the roller core (1 1) and the roller cover (12) or in the roll cover (12) embedded longitudinal extent, on a concentric with the axis of rotation (44) of the roller cylinder surface;

wherein portions of the at least one optical waveguide (21), each containing a fiber Bragg grating (22), with portions of the at least one optical waveguide (21), which are free of a fiber Bragg grating (22), in the longitudinal direction the optical waveguide (21) alternate; and

wherein at least some of the roll core (1 1) and roll cover (12) arranged or embedded in the roll cover (12) embedded fiber Bragg grid-free sections on the cylindrical surface at least partially curved.

Roll (1) for use in paper machines, in particular according to one of the preceding claims, comprising:

a roller core (11);

(22);

wherein the at least one optical waveguide (21) along its between the roller core (1 1) and the roller cover (12) or embedded in the roll cover (12) embedded longitudinal extent at least partially curved and the radius of curvature of curved course of the optical waveguide 2cm or larger, preferably 3cm or larger, more preferably 5cm or larger.

4. Roller according to claim 2 or 3, wherein portions of the at least one optical waveguide (21), each containing a fiber Bragg grating (22), with a circumferential direction to the roller (1) at an angle of less than 80 ° and in particular less than 60 ° and further include in particular less than 45 °.

5. Roller according to one of claims 1 -4, wherein portions of the at least one optical waveguide (21), which are each free of a fiber Bragg grating (22), each curved in a direction of curvature.

6. Roller according to one of claims 1 -5, wherein successive portions of the at least one optical waveguide (21) which are each free of a fiber Bragg grating (22) and between which a portion of the at least one optical waveguide (21), which contains a fiber Bragg grating (22) is arranged, are curved in mutually different directions of curvature.

7. Roller according to one of claims 1 -6, that different portions of the at least one optical waveguide (21), which are each free of a fiber Bragg grating (22), have a length which is a maximum of 30%, preferably a maximum 10% different from one another, particularly preferred that the different sections of the at least one optical waveguide (21), which are each free of a fiber Bragg grating (22) have the same length.

8. Roller according to one of claims 1 -7, wherein the at least one optical waveguide (21) at least along its course in which this between the roller core (1 1) and the roller cover (12) is arranged or embedded in the roll cover (12) , a core and a jacket surrounding the core, wherein the cladding in the area of Sections, each containing a fiber Bragg grating (22), either directly to the roll core (1 1) and the roll cover (12) or directly with the roll cover (12) is in contact.

9. Roller (1) according to any one of claims 1-8, wherein portions of the same optical waveguide, each containing a fiber Bragg grating (22) are arranged adjacent in the axial direction of the roller (1).

10. Roller (1) according to any one of claims 1 -1 1, wherein portions of the same optical waveguide, each containing a fiber Bragg grating (22) are arranged in an over the entire roller length in the axial direction extending portion (3) whose extent in the circumferential direction is less than 15 cm and in particular less than 5 cm and more particularly less than 1 cm.

1 1. Roller (1) according to one of the preceding claims, wherein portions of the same optical waveguide, each containing a fiber Bragg grating (22), in the axial direction of the roller (1) by a constant distance (4) are spaced.

12. roller (1) according to any one of claims 1 -1 1, wherein portions of the same optical waveguide, each containing a fiber Bragg grating (22), in the axial direction of the roller (1) in a first region by a first distance ( 41) and spaced apart in at least a second area by a second distance (42), wherein in particular the second distance (42) by at least 30% and in particular by at least 60% and more particularly at least 90% greater than the first distance (41 ).

A roller (1) according to any one of the preceding claims, comprising more than one optical fiber (21), adjacent portions of different optical fibers (21) each containing a fiber Bragg grating (22) in one over the whole Roller circumference in the circumferential direction extending portion (6) are arranged, whose extension in the axial direction of the roller (1) is less than 10 cm and in particular less than 3 cm and more particularly less than 1 cm.

14 roller (1) according to claim 13, wherein mutually adjacent portions of different optical waveguides (21), each containing a fiber Bragg grating (22) and which are arranged in a region whose extension in the axial direction of the roller (1). is less than 10 cm and in particular less than 3 cm and more particularly less than 1 cm, in the circumferential direction of the roller 45 ° or more, in particular 90 ° or more offset from one another.

15. Roller (1) according to one of the preceding claims, wherein portions of the same optical waveguide, each containing a fiber Bragg grating (22), along a on the surface of the roller (1) described helical curve are arranged, wherein a deviation from the helical curve both in the axial direction of the roller (1) and in the circumferential direction of the roller (1) is less than 15 cm and in particular less than 5 cm and more particularly less than 1 cm.

16 roller (1) according to any one of the preceding claims, wherein at least one end of the at least one optical waveguide from the roll cover (12) is led out and in particular both ends of the at least one optical waveguide from the roll cover (12) are led out.