Force measuring device for sensing the tension of the running paper web.
By designing segmented measuring rollers and load sensors, accurate measurement of paper web tension in the transverse direction is achieved, solving the problem that traditional devices cannot measure transverse tension, and improving the control accuracy and material utilization rate of the processing process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-03-23
- Publication Date
- 2026-03-10
AI Technical Summary
Traditional force measuring devices cannot accurately measure the tension distribution of the paper web along the transverse direction, which affects further processing.
It adopts a segmented measuring roller, with the measuring section sliding and locked on the shaft. Equipped with a load sensor and an electrical conductor, the measuring signal is transmitted to the evaluation unit through the electrical conductor to realize the measurement of the paper web tension distribution in the transverse direction of the paper web.
It can accurately measure the paper web tension distribution in the transverse direction, avoiding waste caused by unsuitable tension conditions and improving the control accuracy of the processing.
Smart Images
Figure CN115667859B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The invention relates to a force measuring device for measuring the web tension of a running web of material, which comprises a longitudinal direction defined by the direction of travel and a transverse direction perpendicular thereto. Here, the force measuring device comprises a shaft and a measuring roller supported on the shaft, which is wound by the web of material. BACKGROUND
[0002] In systems for manufacturing or further processing of web-shaped material, such as paper, plastic or aluminum foil, the web of material is processed in a width of several meters at the beginning of the processing operation. Usually, for further processing, for example in label printing or packaging manufacturing, a considerably narrower web is required, for which the web of material is cut into longitudinal strips of the desired width on a slitting winder. Conventional force measuring devices measure the web tension of the entire web of material over the entire roller width, but in order to cut the web for further processing, it would be advantageous to obtain more precise information about the web tension profile in the transverse direction of the running web. SUMMARY
[0003] This is where the invention begins. The object of the invention is to provide a force measuring device of the type described above, with which the web tension profile in the transverse direction of the running web of material can be measured.
[0004] According to the invention, in a conventional force measuring device, there is provided:
[0005] The measuring roller is formed as a segmented measuring roller having two or more measuring segments, which are able to slide individually on the shaft and are able to be locked in a measuring position on the shaft, in order to position the measuring segments in the transverse direction of the web of material according to the desired measuring position, so that each longitudinal portion of the web of material is wound around one measuring segment,
[0006] Each measuring segment comprises a load cell for determining the web tension of the longitudinal portion of the web of material wound around the respective measuring segment and a mounting by which the measuring segment is located on the shaft, and
[0007] The shaft is equipped with an electrical conductor, which extends substantially in the axial direction over the entire width, which is able to be contacted at each position in the axial direction, and by which the measuring signals provided by the load cells of the measuring segments are able to be conducted to an evaluation unit arranged at the shaft end.
[0008] The electrical conductor of the shaft can be arranged in an inner axial chamber, for example a guide chamber, described in more detail below, but also on the outside of the shaft, for example in an axial outer recess of the shaft. It is important here that the electrical conductor is accessible in each axial position to which the measuring section can be locked, that is to say substantially in each position along the width of the shaft, so that the measurement signal provided by the load cell can be conducted to the evaluation unit irrespective of the respective measuring position of the measuring section.
[0009] The measuring section advantageously comprises, in addition to the load cell, a roller shell and a bearing of the roller shell supported by the load cell.
[0010] In a preferred embodiment, the load cell comprises in each case an inner ring on the shaft, which inner ring provides the mounting. The load cell further comprises a concentric outer ring which can slide relative to the inner ring upon application of force and a measuring portion which connects the inner ring and the outer ring in a connection region. Upon application of force when measuring the paper web tension, the outer ring slides radially relative to the inner ring as a result of which a tension occurs in the measuring portion which can be measured by a strain gauge.
[0011] The inner ring particularly advantageously comprises a recess in which the connection region of the outer ring is accommodated. This recess can extend radially to half the radius of the inner ring, preferably even to the middle of the inner ring. The load cell is advantageously guided in an axial guide chamber of the shaft with the recess of the inner ring. In this way, a particularly compact construction of the load cell and the force measuring device is achieved, in addition, the load cell is integrated with the shaft of the force measuring device.
[0012] According to an advantageous variant of the application, the inner ring and the outer ring are arranged radially nested and are connected in a radial connection region by the measuring portion. As an overload protection, the inner ring and the outer ring are preferably separated outside the connection region by a narrow radial gap which is dimensioned in such a way that in the event of an overload, the movable outer ring comes to rest against the inner ring which is fixed on the shaft. The gap width corresponds to, for example, 110% of the measurement path under nominal load and is typically in the range of tenths of a millimeter.
[0013] In another equally advantageous embodiment, the inner ring and the outer ring are arranged axially spaced apart and are connected in an axial connection region by the measuring portion.
[0014] The load cell is advantageously equipped with a strain gauge for measuring the paper web tension. Preferably, the measuring portion which connects the inner ring and the outer ring is equipped with the strain gauge for measuring the mechanical tension which occurs in the measuring portion.
[0015] In an advantageous embodiment, the measuring portion is formed in the form of a double-bending beam.
[0016] The inner ring, the outer ring and the measuring portion of the load cell are particularly advantageously formed as one piece.
[0017] According to a preferred embodiment, the shaft is formed as an extruded profile. The extruded profile preferably comprises a vertical ridge and two horizontal rails extending from the vertical ridge, such that the vertical ridge and the two rails form a U-shaped axial guide cavity in the extruded profile of the shaft.
[0018] Alternatively, the shaft can also be formed as a milled shaft, wherein the axial guide cavity and further recesses, if applicable, such as axial grooves for air hoses and pressure bars, are milled into a round bar. The manufacture of the shaft as a milled element is simple and inexpensive, but does not allow radially closed hollow spaces and thus generally has a higher weight than an extruded profile with the same bending resistance.
[0019] The shaft is advantageously equipped in the axial guide cavity with an axially extending power supply rail, which can contact at any axial position of the current collector in the load cell of the measuring segment and forms the electrical conductor. Particularly advantageously, in the axial guide cavity, the load cell is guided by the recess of the inner ring and is provided with the axially extending power supply rail.
[0020] Each measuring segment preferably comprises an electronics unit for providing the strain gauge, preferably in addition to digitization also for receiving, pre-amplifying and also for releasing the pre-amplified and digitized, if applicable, measurement signal into an electrical line, in particular into the power supply rail in the shaft. Digitization of the measurement signal is advantageous, in particular when the segmented measuring roller comprises a large number of measuring segments, for example four or more or six or more measuring segments, since the digitized measurement signal can then be conducted to the evaluation unit via a few, usually two, power supply lines using a bus protocol. The measurement signal can of course also be conducted to the evaluation unit in analog form, each measurement signal via its own power supply line, in particular when the segmented measuring roller comprises only a small number of measuring segments.
[0021] For measuring the rotational speed, each measuring segment is advantageously equipped with a device for measuring the rotational speed, which preferably comprises one or more magnets rotating with the roller shell and a static Hall effect generator connected with the load cell. From the Hall voltage generated upon rotation, the rotational speed of each measuring segment can be determined in a manner known to the person skilled in the art and conducted via the electronics unit to the evaluation unit. The individual determination of the rotational speed of each measuring segment in particular allows to determine whether a slip has occurred in one or more measuring segments in operation.
[0022] In a preferred embodiment, the shaft comprises in the axial recess an air hose and a pressure bar for locking the measuring segments on the shaft. Here, the evaluation unit preferably comprises a pressure sensor for monitoring the air pressure of the air hose. In the event of a deviation of the air pressure from a target value, the evaluation unit can for example emit a warning signal or initiate other suitable measures.
[0023] In an advantageous embodiment, each measuring segment is equipped with lateral spacers, the dimensions of which are coordinated with the dimensions of the respective roll shell, so that the measuring segments can be slid together on the shaft so that the roll shells adjoin with virtually no gap without touching each other. In practice, this means that in the slid-together state the gap of the roll shells is a few tenths of a millimeter to about one millimeter.
[0024] Two or more, in particular three or more, four or more or even six or more, measuring segments are advantageously positioned and locked on the shaft so that the measuring roll forms a segmented measuring roll with two or more, three or more, four or more or even six or more measuring segments.
[0025] In an advantageous embodiment, each measuring segment is positioned and locked on the shaft with roll shells that are spaced apart so that the segmented measuring roll is particularly suitable and configured to measure the web tension of the longitudinal strips of the running material web that are cut. The number and position of the measuring segments and the width of their roll shells are suitably adapted to the number, position and width of the longitudinal strips of the material web that are cut.
[0026] In another equally advantageous embodiment, the measuring segments are positioned and locked on the shaft in such a way that their roll shells adjoin with virtually no gap without touching each other. The segmented measuring roll is then particularly suitable and configured to measure the web tension of the longitudinal sections of the running material web that are not cut and thus to measure the tension profile in the cross direction of the material web. The number and position of the measuring segments and the width of their roll shells are suitably adapted to the resolution requirements of the tension profile measurement.
[0027] The force measuring device according to the invention enables local measurement of the web tension in the cross direction of the running material web in individual longitudinal strips of the cut web and in longitudinal sections of the uncut web. It is understood that during operation of the force measuring device, each slidable and lockable measuring segment is locked in a position that corresponds to the position at which a desired web tension measurement is to be made. If a web tension is subsequently to be measured with the force measuring device, another tension profile or another longitudinal strip configuration of the web, the locking is released and the measuring segments are slid on the shaft and relocked accordingly. If a different number of measuring segments is required, or if a different width of the measuring segments is required, the measuring segments can also be removed from the shaft and / or additional or different measuring segments of the desired width can be pushed onto the shaft. The described force measuring device can thus be very flexibly adapted to the respective measurement work and measurement requirements.
[0028] By measuring the web tension of the longitudinal strips of the cut web, the winding process can be controlled individually, so that a large amount of waste due to inappropriate tension conditions in the individual longitudinal strips is avoided. It is also very beneficial to know the tension profile for the web of the uncut material. For example, when manufacturing blown film, by measuring the tension profile of the produced film tube, the cooling profile of the melt tube can be readjusted to obtain a uniform tension profile of the film tube. BRIEF DESCRIPTION OF DRAWINGS
[0029] Other exemplary embodiments and advantages of the application are explained in the following description taken in connection with the accompanying drawings, in which, for the purpose of providing an overall understanding of the application and the specific features thereof, some
[0030] is shown:
[0031] Figure 1 A web of material cut into longitudinal strips is schematically shown, wherein the web tension of the longitudinal strips is to be measured individually;
[0032] Figure 2 A force measuring device according to the application is schematically shown;
[0033] Figure 3 A cross section of the force measuring device according to the application in the direction of line III-III in Figure 2 is shown;
[0034] Figure 4 A cross section of the load cell of the measuring section of the force measuring device in Figure 3 is shown;
[0035] Figure 5 A perspective view of the load cell in Figure 4 is shown;
[0036] Figure 6 A perspective view of the shaft of the force measuring device in Figure 3 is shown;
[0037] Figure 7 A cross section of the shaft in Figure 6 is shown in (a), a milled shaft according to another exemplary embodiment of the application is shown in (b);
[0038] Figure 8 A load cell in Figure 4 is shown, having an electronic circuit board and a contact area with a strain gauge and a power supply rail of the pull-in shaft;
[0039] Figure 9 A cross section of a load cell according to the application is shown, having a measuring section extending in the axial direction;
[0040] Figure 10 A force measuring device according to the present application is schematically shown, which is configured to record the tension profile of an uncut material web; and
[0041] Figure 11 A tension profile of an uncut material web measured with the force measuring device according to the present application is schematically shown, wherein the force F is plotted over the dimension x in the transverse direction. Figure 10 DETAILED DESCRIPTION
[0042] The present application will now be explained using an example of a force measuring device for measuring the web tension of a material web running through a cut.
[0043] Figure 1 A material web 10 is shown by way of example, whose running direction defines a longitudinal direction L and a transverse direction Q perpendicular thereto. In the exemplary embodiment, the material web 10 is cut into n = 6 longitudinal strips, namely one longitudinal strip 12-1 having an average width, two wider longitudinal strips 12-2, 12-3 and three narrower longitudinal strips 12-4, 12-5, 12-6.
[0044] For the subsequent winding process of the longitudinal strips, it is advantageous to know the web tension in each strip individually. While conventional measuring devices only allow the web tension of the entire web 10 over the entire roll width to be measured, the force measuring device 20 of the present application described below is capable of measuring the web tension in each of the plurality of longitudinal strips 12-i (i = 1... 6) of the material web 10 individually.
[0045] Figure 2 A force measuring device 20 according to the present application is schematically shown. The force measuring device 20 comprises a bending-resistant shaft 22, the two ends of which are located on an unshown field substructure. A measuring roll 30 is supported on the shaft 22, around which, in operation, the material web 10 to be measured is wound.
[0046] According to the present application, the measuring roll is formed as a segmented measuring roll 30, which, in the exemplary embodiment, serves to measure the web tension of the 6 longitudinal strips 12-i of the material web 10 in Figure 1 and thus consists of n = 6 measuring segments 32-i, wherein i = 1... 6, which are adapted to the longitudinal strips 12-i.
[0047] As shown in Figure 2 , the width of the measuring segments 32-i can be different, in particular the width of their roll shells, but in addition thereto, their structural features are preferably formed equally. The following description of the measuring segments thus applies to all measuring segments 32-i of the measuring roll 30, and therefore, for the sake of simplicity, the index i is generally omitted.
[0048] The measuring segments 32 are able to slide individually on the shaft 22 and are able to be locked in a measuring position on the shaft, so that they can be positioned in the transverse direction Q of the material web 10 according to the desired measuring position, so that each longitudinal strip 12-i of the material web 10 is located on the roll shell 34 of the associated measuring segment 32-i and is wound around said roll shell. The roll shell 34 of the measuring segment is connected in each case via a rolling bearing 38 with a load cell 36 for determining the web tension of the longitudinal portion 12 of the material web 10 wound around the respective measuring segment. Furthermore, the load cell 36 provides a mounting by which the respective measuring segment 32 is located on the shaft 22.
[0049] As shown in Figure 1 and 2 , the width of the roll shell 34 of the measuring segment 32 is adapted to the width of the associated longitudinal strip 12 of the material web. In the exemplary embodiment, the measuring roll 30 thus consists of a measuring segment 32-1 with an average-width roll shell, two measuring segments 32-2, 32-3 with a wider roll shell and three measuring segments 32-4, 32-5, 32-6 with a narrower roll shell.
[0050] The shaft 22 is equipped with an electrical conductor 26 which extends substantially in the axial direction through the entire width, which electrical conductor is able to be contacted at each position in the axial direction and by means of which the measuring signals provided by the load cells 36 of the measuring segments 32 are conducted to an evaluation unit arranged at the shaft end 28. Here, the electrical conductor 26 can be arranged outside the shaft 22, for example in an axial recess, but the electrical conductor can also advantageously be present in a guide cavity in the shaft, which will be described in more detail below. The measuring segments 32 are also equipped with spacers 40, the function of which is explained in more detail in Figure 10 .
[0051] A favorable development of the measuring segments 32 and the shaft 70 of the force measuring device according to the application will now be described in more detail with reference to Figures 3 to 7 . Here, Figure 3 a cross section of the force measuring device 20 is shown in the direction corresponding to the center line III-III in Figure 2 . The load cells 36 of the measuring segments 32 are shown individually in cross section in Figure 4 , in perspective view in Figure 5 , the shaft 70 is shown individually in perspective view in Figure 6 , in cross section in Figure 7 .
[0052] With reference first to Figure 3 , the measuring segment 32 comprises radially from the outside to the inside a roll shell 34, a rolling bearing 38 and a load cell 36. The longitudinal strip 12 of the material web 10 wound around the measuring segment 32 is indicated by a dashed line.
[0053] Here, in Figure 4 and 5 The load sensor 36, shown separately again, includes an outer ring 50, a concentric inner ring 52, and a measuring portion 54 with an H-shaped recess 56. The outer ring 50 includes a notch 58. Figure 5 The inner ring 52 is located on the shaft 70 and provides the aforementioned mounting element, used to retain the rolling bearing 38 via a retaining ring (not shown). In an exemplary embodiment, the inner ring 52 and the outer ring 50 are arranged to be radially nested and connected in a radially connected region by a measuring portion 54. For this purpose, the inner ring 52 includes a notch 66 extending radially to the center of the inner ring 52. On the one hand, the notch 66 accommodates the connection region with the outer ring, and on the other hand, it serves as a guide cavity 80 in the axial direction of the shaft 70 (…). Figure 7 The load sensor is firmly guided in the middle.
[0054] The outer ring 50, the inner ring 52, and the measuring section 54 form a single unit. Figure 3 and Figure 4 The different shaded lines are only used to indicate the different functional areas 50, 52, and 54 of the load sensor 36.
[0055] Outside the connection area, the inner and outer rings are separated by a radial gap 60, the width of which is designed such that, under overload conditions, the movable outer ring 50 abuts against the inner ring 52 fixed to the shaft 70, thus preventing plastic deformation and therefore damage to the load sensor 36. In an exemplary embodiment, the width of the gap 60 is adapted to 110% of the measurement path under nominal load.
[0056] Due to the H-shaped recess 56, the measuring portion 54 forms a double-bending beam, wherein, in the exemplary embodiment shown, a strain gauge 62 is disposed on its top side for measuring the mechanical tension generated on the material surface by applying force. It should be understood that the strain gauge 62 may also be disposed on the bottom side of the double-bending beam, or on both the top and bottom sides.
[0057] The longitudinal strips 12 of the material web winding around the measuring section 32 generate a force 64, which depends on the wrap angle and the web tension. This force pushes the movable outer ring 50 of the load sensor 36 downward relative to the fixed inner ring 52, thus causing the double-bending beam of the measuring section 54 to bend. This bending is measured by the strain gauge 62, which generates a corresponding electrical signal. This signal is pre-amplified by the electronic unit in the measuring section 32 and transmitted in a suitable form via the power rail of the shaft 70 to the evaluation unit 28.
[0058] refer to Figure 3 , 6and 7 (a), in the exemplary embodiment shown, the shaft 70 is formed as an extruded profile which can accommodate a plurality of individually measured measuring segments 32 across its width, as Figure 2 and 10 is schematically shown. The shaft 70 is formed as an extruded profile so that the shaft can be formed in a flexurally rigid manner, i.e. it does not deform or only minimally deforms even under maximum load due to high paper web tension, thus not affecting the geometric arrangement of the measuring segments across the width or the paper web tension measurement.
[0059] In the exemplary embodiment, the extruded profile shaft 70 is formed with a circular cross-sectional circumference 75. It comprises a central vertical ridge 72 from which two horizontal rails 74, 76 and a guiding curve 78 extend, which together with the ridge 72 form a U-shaped axial guiding cavity 80 in the shaft 70 into which the recess 66 of the inner ring 52 reaches for guiding and electrically connecting the load cells (not shown). Figure 3 The curvature of the guiding curve 78 and the radially outer surface of the rails 74, 76 is adapted to the curvature of the inner ring 52 with tight tolerances so that on the one hand the measuring segments 32 can easily be slid on the shaft, but on the other hand can also be easily and securely locked by means of, for example, a mechanical or pneumatic locking mechanism.
[0060] In order to conduct the electrical signals generated by the strain gauges 62 of the measuring segments 32 to the evaluation unit 28, the lower horizontal rail 76 of the shaft 70 is equipped in the recessed area with an axially extending power supply track 82 which facilitates the supply of power and the electrical contact with the measuring segments 32 regardless of their position on the shaft 70. It is understood that the power supply track can also be provided at another location in the guiding cavity, for example on the upper rail 74 or also on both rails 74, 76.
[0061] As Figure 7 (b) shows, instead of an extruded profile, the shaft can also be formed as a milled shaft 170 in which a U-shaped axial guiding cavity 80 and an axial recess 84 are milled. Here, the shaft body 172 comprises a central vertical support structure which ensures the stability of the shaft, from which two horizontal rails 174, 176 extend to form the U-shaped axial guiding cavity 80 in the shaft 70 together with the shaft body 172 within the cross-sectional circumference 175 into which the recess 66 of the inner ring reaches for guiding and electrically connecting the load cells.
[0062] As Figure 8As shown, in addition to the mechanical elements already described, the load sensor 36 also comprises a circuit board 90 which has electrical couplings which, in order to provide and receive the measurement signals, are connected to the strain gauges 62 in a contact area 92 and can establish contact with the power rails 82 at any axial position of the shaft 70 via current collectors 94. In the exemplary embodiment shown, the electrical couplings of the circuit board 90 comprise preamplifiers for processing the signals, which amplify and digitize the measurement signals of the strain gauges 62 and relay the digitized measurement signals to an internal bus.
[0063] An evaluation unit 28 is arranged at one end of the shaft, which evaluation unit is in communication with the measurement segments 32-i on the shaft 70 and receives and further processes their measurement values. To this end, in the exemplary embodiment, the power rails 82 comprise, in addition to the two power rails for supplying power, a further two power rails for transmitting data to the evaluation unit 28, for example in accordance with the RS-485 standard. If the measurement roll comprises only a few measurement segments, or if, for other reasons, no digitization takes place, the measurement signals, which are preamplified, can of course also be conducted to the evaluation unit in analog form, each measurement signal being conducted via its own power rail.
[0064] The evaluation unit 28 communicates, as such, via a standardized bus protocol with a higher-level controller which triggers appropriate actions, for example, makes the drive run slower or faster, emits a warning signal, etc., on the basis of the measurement values provided by the different measurement segments 32.
[0065] In the exemplary embodiment, the measurement segments 32 are reliably locked on the shaft 70 by means of axial air hoses 86 and axial pressure strips 88 which are both embedded in grooves 84 formed in the guide curve 78 of the shaft 70. Figure 3
[0066] In the relaxed state of the air hoses 86, the measurement segments 32 are able to slide freely on the shaft and can be set in the desired number at the desired position on the shaft. If the air hoses 86 are subsequently inflated, they press with an air pressure-dependent force on the pressure strips 88, thus pushing the pressure strips slightly radially out of the grooves 84. As a result, the pressure strips 88 clamp the positioned measurement segments 32 against defined stops on the shaft 70 and in this way simultaneously lock all the measurement segments 32 in their correct position. By relaxing the air hoses 86, the locking is again released and the measurement segments can be slid and / or exchanged. The air pressure of the air hoses 86 is monitored by a pressure sensor in the evaluation unit 28 arranged at the shaft end.
[0067] In a further variant of the application, instead of air hoses and pressure strips, it is provided that each measurement segment 32 is equipped with a mechanical locking device by means of which the measurement segment can be fixed individually on the shaft.
[0068] In the exemplary embodiment described in Figures 3 to 8 , the measuring section 54 extends in radial direction between an inner ring and an outer ring, which is currently preferred due to the simpler construction and the high positive tension. However, it is also possible that the measuring section of the measuring section extends in axial direction, as explained below with reference to the exemplary embodiment in Figure 9 , in which a measuring section 100 according to the application is shown schematically in side view.
[0069] The measuring section 100 comprises a load cell 102, which comprises an outer ring 110, an axially spaced concentric inner ring 112 and an axial measuring section 114. The inner ring 112 is seated on the shaft 22 with a small tolerance, indicated in the drawing by a dashed line, so that it can be slid along the shaft in the untensioned state. The outer ring 110 bears externally on the bearing cage of the rolling bearing 38, on the outer circumference of which the roll shell 34 is connected.
[0070] The outer ring 110 and the inner ring 112 are connected by the axial measuring section 114, which in the exemplary embodiment comprises a substantially H-shaped recess 116 and forms a double bending beam, which is equipped with a strain gauge 62 for measuring the tension of the measuring section 114. The outer ring 110 is dimensioned with respect to the shaft 22 with a tolerance such that in the event of an overload, the outer ring rests against the shaft 22 and in this way prevents any damage to the load cell 102.
[0071] If, as a result of the web tension, a force 64 presses on the roll shell 34 of the measuring section 100, this force is transmitted via the rolling bearing to the outer ring 110, which rests via the measuring section 114 on the inner ring 112. The tension generated in this way in the measuring section 114 is measured by the strain gauge 62 and the electrical signal generated is preamplified as already outlined above, if applicable digitized, and transmitted into the power supply line of the shaft 22. The fixing of the measuring section 100 on the shaft can take place, for example, mechanically or pneumatically, as also described above.
[0072] In addition to measuring the web tension of the cut longitudinal strips of the material web, the force measuring device according to the application also allows the tension profile of the uncut material web to be recorded by independent web tension measurement of the measuring section.
[0073] To this end, reference is made to Figure 10 , the measuring section 32 of the force measuring device 20 is positioned and locked on the shaft 22 in such a way that its roll shells 34 are adjacent without mutual contact (reference 120) with virtually no play. To ensure this, the measuring section 32 is equipped with lateral spacers 40 (reference 122) which are attached to the roll shells 34 and which are dimensioned in such a way that the roll shells 34 are pressed against each other with a defined force. Figure 5Its dimensions are coordinated with the corresponding roller shell 34, so that when the measuring sections 32 are pushed together, the desired side-by-side arrangement 120 with almost no gap is achieved, with the gap between the roller shells being a few tenths of a millimeter.
[0074] Since each measuring segment 32 measures the local paper web tension BZ(x) at the corresponding position x along the transverse direction Q of the paper web, multiple measuring segments 32 can be used to measure the tension distribution 122 of the paper web, such as... Figure 11 The diagram is schematically illustrated. In the tension distribution diagram shown here, the local paper web tension Bz(x) is plotted on the spatial coordinate x in the transverse direction of the paper web. From the knowledge of the tension distribution, appropriate measures can be derived; for example, for an uneven distribution, control measures can be taken to produce a more uniform tension distribution. If, for example, the time progression of the local paper web tension is displayed in a waterfall diagram, periodic signals, such as non-circular feed rolls, periodic wrinkling, etc., can also be easily identified.
[0075] The width of the measuring segment 32 used for tension distribution measurement can be the same, such as in... Figure 10 In the exemplary embodiment, however, it is also advantageous to use measuring segments 32 of different widths. For example, in the middle region of the paper web, measuring segments with narrower roll shells than those in the edge regions of the paper web can be used.
[0076] By measuring the rotational speed of individual measuring segments 32, it can be determined whether slippage has occurred in one or more measuring segments. Here, in each case, the segment with the fastest rotation provides a reference value. To determine the rotational speed of the measuring segments 32, for example, two segments offset from each other by 180 degrees can be installed in each measuring segment via mounting members 130 on the roller shell 34. o Magnet 132, such as Figure 3 As shown. The load sensor 36 is equipped with a Hall effect generator at a suitable location. When the roller shell 34 rotates, the magnet 132 periodically passes through the Hall effect generator, generating a Hall voltage. The rotational speed of the measurement section can be determined from the time progression of this Hall voltage. The signal from the Hall effect generator is transmitted via an electronic unit (…). Figure 8 The data is transmitted to the evaluation unit and evaluated. For example, the rotational speed of the fastest rotating measurement segment is defined as a reference value, and for measurement segments with rotational speeds lower than a predetermined threshold than the reference value, slippage is displayed.
Claims
1. A force measuring device for measuring the web tension of a running material web, the material web comprising a longitudinal direction defined by a running direction and a transverse direction, the force measuring device comprising a shaft and a measuring roll supported on the shaft and wound by the material web, characterized in that - the measuring roll is formed as a segmented measuring roll having two or more measuring segments, which are individually slidable on the shaft and lockable in measuring positions on the shaft in order to position the measuring segments in the transverse direction of the material web depending on the desired measuring position, so that each longitudinal section of the material web is wound around one measuring segment, - each measuring segment comprises a load cell for determining the web tension of the longitudinal section of the material web wound around the respective measuring segment and provides a mounting by which the measuring segment is located on the shaft, and - the shaft is equipped with an electrical conductor which extends substantially in the axial direction through the entire width, which is contactable at each position in the axial direction, and by which the measuring signals provided by the load cells of the measuring segments can be conducted to an evaluation unit arranged at the shaft end.
2. The force measuring device of claim 1, wherein, In addition to the load cell, the measuring segment comprises a roll shell and a bearing of the roll shell supported by the load cell.
3. The force measuring device of claim 1, wherein, In each case, the load cell comprises an inner ring located on the shaft and providing the mounting, a concentric outer ring which is slidable relative to the inner ring, and a measuring portion connecting the inner ring and the outer ring in a connection region.
4. The force measuring device of claim 3, wherein, The inner ring comprises a recess in which a connection region of the outer ring is accommodated.
5. The force measuring device of claim 4, wherein, The load cell is guided in an axial guide cavity in the shaft with the recess of the inner ring.
6. The force measuring device of claim 3, wherein, The inner ring and the outer ring are arranged radially nested and connected in the radial connection region by the measuring portion.
7. The force measuring device of claim 3, wherein, The inner ring and the outer ring are arranged axially spaced apart and connected in the axial connection region by the measuring portion.
8. The force measuring device of claim 1, wherein, The load cell is equipped with a strain gauge for measuring the web tension.
9. The force measuring device of claim 8, wherein, The measuring portion connecting the inner ring and the outer ring is equipped with the strain gauge for measuring the mechanical tension generated in the measuring portion.
10. The force measuring device of claim 3, wherein, The measuring portion is formed in the form of a double-bending beam.
11. The force measuring device of claim 3, wherein, The inner ring, the outer ring and the measuring portion of the load cell are formed as one piece.
12. The force measuring device of claim 1, wherein, The shaft is formed as an extruded profile comprising a vertical ridge and two horizontal rails extending from the vertical ridge, which form a U-shaped axial guide cavity in the extruded profile of the shaft.
13. The force measuring device of claim 1, wherein, The shaft in the axial guide cavity is equipped with an axially extending power supply track which is contactable at any axial position of a current collector in the load cell of the measuring segment and forms the electrical conductor.
14. The force measuring device of claim 8, wherein, Each measuring segment comprises an electronic unit for providing the strain gauge, in addition to digitization, for receiving, pre-amplifying, and also for transmitting the pre-amplified digitized measuring signal into the electrical line.
15. The force measuring device of claim 2, wherein, Each measuring segment is equipped with a device for measuring the rotational speed.
16. The force measuring device of claim 15, wherein, The device comprises one or more magnets rotating with the roll shells of the measuring section and a static Hall effect generator connected with the load sensor of the measuring section.
17. The force measuring device of claim 1, wherein, The shaft comprises in the axial recess an air hose and a pressure bar for locking the measuring section on the shaft.
18. The force measuring device of claim 17, wherein, The evaluation unit comprises a pressure sensor for monitoring the air pressure of the air hose.
19. The force measuring device of claim 1, wherein, Two or more measuring sections are positioned and locked on the shaft.
20. The force measuring device of claim 19, wherein, A measuring section for measuring the web tension of a longitudinal strip of a running web of cut material is positioned and locked on a shaft with spaced apart roll shells.
21. The force measuring device of claim 19, wherein, A measuring section for measuring the web tension of a longitudinal section of a running web of uncut material is positioned and locked on a shaft in such a way that its roll shells are adjacent with little gap and without touching each other.
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