WO2008059105A1

WO2008059105A1 - Method in connection with a fibre-web machine winder

Info

Publication number: WO2008059105A1
Application number: PCT/FI2007/050595
Authority: WO
Inventors: Tatu PITKÄNEN; Petteri Lannes; Teppo Kojo; Marko Tiilikainen
Original assignee: Metso Paper Oy
Current assignee: Valmet Technologies Oy
Priority date: 2006-11-13
Filing date: 2007-11-06
Publication date: 2008-05-22
Anticipated expiration: 2009-05-13
Also published as: FI119980B; FI20065716L; AT507933B1; FI20065716A0; AT507933A1; DE112007002607T5

Abstract

The invention relates to a method in connection with a winder of a fibre web in which method the fibre web (W) is wound up and/or unwound and a characteristic affecting and/or forming in the winding of a fibre-web roll (11) being wound is measured by at least one measuring sensor (13). Measuring results are processed for detecting a sudden change occuring on the periphery of the fibre-web roll (11) in the machine direction for detecting and identifying pulse-like winding defects for defining and controlling the inner quality and structure of the fibre-web roll (11).

Description

Method in connection with a fibre-web machine winder

The invention relates to a method in connection with a winder of a fibre-web machine according to the preamble of claim 1.

From prior art are known windups used in connection with fibre-web machines, such as paper and board machines, a fibre web being manufactured by which fi- bre-web machines, such as a paper machine/board machine, is wound as a full- width web into machine rolls for further processing. The web is wound around a winding shaft e.g. a spool iron/roll either by means of surface draw in a winding nip between a winding drum and a web roll being formed or by utilising a centre drive, whereby also the winding shaft is provided with a drive. In connection with fibre-web machines, such as paper and board machines, are also used unwinders by means of which the web roll wound by the windup is unwound in a later stage of treatment for further processing of the fibre web.

As known from prior art, the machine roll of the fibre-web machine is aimed to be structured by means of the winding parameters of the windup so that the roll endures braking, accelerating, short-term storage and so that the roll will unwind in the next process stage easily and accurately. The final structure of the roll is not formed until unwinding, because defects can be created in the roll in all preceding process stages. On the windup, forming the structure of the roll as tight enough for further processing has been aided by adjusting winding parameters, such as nip force, peripherical force and web tightness. The quality and structure of the roll have been observed e.g. by gauges exploring hardness on the surface of the roll into the roll and/or by manually exploring the surface of the roll for detecting possible winding defects. In methods known from prior art, it has been very difficult to define e.g. the local tangential and radial stresses inside the roll, because locating the measuring sensors inside the roll is difficult, even impossible, with high speeds and because the sensors easily break the web. Furthermore, such sensors do not measure the actual situation, because the sensor increases local stress. From prior art are also known roll structure tests in which a measuring tab (a pull tab) is fed along the web into the roll/onto the roll surface and, when the roll has been completed, the tab is pulled out and pulling force is measured which is proportional to the radial pressure between the layers of the roll. With these pull tabs, it has thus been possible to define the radial pressure inside the roll at the end of the machine or customer roll, but it is not possible to obtain more detailed information on the inner structure of the roll with this method. Because of these reasons, mostly winding defects have been identified in unwinding, but in this stage it is hard to form a correlation with the cause of the defect in winding-up.

For the part of prior art, we refer to FI patent specification 105803 which describes a method in continuous unwinding of a paper web in which the shape of the outer surface of the paper roll being unwound is measured with the aim of detecting defects possibly occurring in the paper roll.

For the part of prior art, we refer to international specification PCT/DE98/03204 in which a neural network is trained in measurements correlating with the roll quality of the slitter-winder, e.g. web tightness, the number of paper layers in the roll and the radius of the roll. According to the specification, the trained neural network adjusts the quality of the roll by means of these factors. The specification describes the used adjustment algorithm but not the actual method for measuring the winding quality.

When the run speeds of winders increase and the quality level of the webs (smoothness, density, gloss etc.) improves, the risk of the breaking of the machine roll increases. A small momentary profile defect or a malfunction in winding pa- rameters can cause the breaking of the surface layers of the machine roll, which is a great safety risk as it can lead to both bodily injury and material damage.

The object of the invention is to eliminate or at least minimise the disadvantages and problems of the above-described arrangements according to prior art.

An object of the invention is to create a measuring and control system of winding quality applicable in connection with a fibre-web winder, a wind-up or an unwinder, by means of which the inner quality and structure of the machine roll can be defined and controlled.

A more particular object of the invention is to eliminate problems related to the possible breaking risk of the machine roll.

To achieve the above-mentioned objects and those which come out later, a method according to the invention is mainly characterised by what is presented in the characterising part of claim 1.

According to the invention is provided an identification and control system of possible pulse-like winding defects based on measuring which is applicable in one or more winding points. A pulse-like winding defect is a single winding defect which can be observed on the periphery of the roll as a sudden change in the machine direction at most in one cycle i.e. it can be observed pulse-like when the roll rotates a whole cycle.

According to an advantageous embodiment of the invention, the measurement is implemented so that a measuring sensor/sensors or equivalents is/are located onto the surface of a roll or equivalent forming a nip with the roll being wound. Such a roll can be a winding shaft, a carrier roll, a pressure roll or a separate roll arranged in nip contact with the roll being wound. According to an advantageous embodiment of the invention, in connection with the winding of a fibre web, the roll profile and advantageously the nip force profile are measured by an advantageously spiral-like sensor formed of pressure- sensitive foil or by more sensors, at least two, advantageously four sensors located on the surface of a roll or equivalent forming a nip with the roll being wound. The measuring foil can be positioned straight i.e. in the direction of the longitudinal axis of the roll or spirally or in the direction of the periphery extending either to the whole periphery or a portion of it. From the measuring results is obtained information on sudden changes occurring in the profile which indicate damages of the roll and the start of the breaking of the roll.

The above-described advantageous embodiment of the invention is advantageously used in such winding which utilises a pressure-sensitive foil, a so-called EMFi foil, in measuring the nip load, by means of which measuring foil the nip load and the cross profile of nip force can be measured easily and accurately. It is also possible to identify winding defects in the measurement signal of such a foil measuring application by providing, if required, the measuring device with additional sensors or suitable electronics. It is also possible to form a machine roll defect diagram of the measuring results for preventing defects already in the winding-up stage.

When applying the above-described advantageous embodiment of the invention in connection with a windup, during winding are identified possible winding defects occurring in the roll from the measurement signal of the pressure-sensitive foil sensor e.g. with the same principle as feeling with a hand defects on the surface of the roll i.e. by detecting a deviation occurring once in a cycle. Simultaneously by means of the invention, an indication of the burst of the roll is obtained, when based on the measurement signal are observed the pre-stages of the breaking of the roll surface, whereby the burst can be prevented so that the web incoming to the windup is cut and the winding is stopped before the burst. When applying the above-described advantageous embodiment of the invention in connection with an unwinder, a pressure-sensitive foil sensor is located on the surface of a roll in nip contact with the roll being unwound, whereby the winding defects created in the roll in connection with winding-up and furthermore based on the measurement signal are identified crepe wrinkles and equivalent defects created of internal stresses of the roll during winding-up or unwinding which can be eliminated e.g. by an intermediate winder so that the structure of the roll is changed in the winding-up of the intermediate winder e.g. by winding the bottom of the roll tighter.

From the measurement signal is calculated a difference profile compared with a reference profile and both minimum and maximum peaks of the difference profiles are defined, pattern recognition is performed and based on the upper/lower limit alarm are performed possibly required run parameter changes and/or safety precautions.

The defect definition based on a pressure-sensitive foil sensor according to an advantageous embodiment of the invention is applicable in connection with wind- ups, partial web winders and unwinders. In connection with windups, the inven- tion can be applied in the prevention of the burst of the roll and in the identification of a break point caused by a crepe wrinkle in connection with unwinders and windups. With partial web winders, the above-mentioned factors are detected by means of the invention. The invention is also applicable in connection with coating or an unwinder of a calender, whereby into connection with the unwinder in a suitable position e.g. against the roll surface or as a lead roll of an unwinding web is located a roll provided with a pressure-sensitive foil sensor which can also operate as the tail catcher in break situations. In these embodiments, it is thus possible to cut the web or stop the machine before bottom crepe wrinkles and additionally identify possible winding defects unnoticed in earlier measurements or later created and to prevent their access on coating stations or the calender, whereby the danger would be the breaking of calender rolls or a web break. In some other advantageous embodiments of the invention, a microwave radar or a laser is used for indicating crepe wrinkles and other winding defects instead of the pressure-sensitive foil sensor. Then into connection with the winder are in- stalled required measuring devices by means of which the roll radius and the surface shape are measured on the surface of the roll and a little inside the surface. The measuring sensors can be located either locally in desired measuring points or scanning measurement can be used in a desired area. The processing of measuring data and the identification of possible winding defects take place either directly observing the measurement signal or by forming a spectre of the measurement signal. The direct measurement signal observation is based on identifying the signal form given by the winding defect and on the continuous comparison of the measured signal with the known signal. In the examination of the spectre, the measuring data of several winding cycles are processed. The possible breaking risk of the roll is aimed to be identified in an as-early-as-possible stage in order to be able to interrupt the process before the breaking of the machine roll surface. Thus, it is possible to minimise the safety risk and the damages or even eliminate them. In the case of a risk occurring, it is possible e.g. to decrease run speed, to cut the web or to perform an emergency stop.

According to an embodiment of the invention, in connection with winding is used a measuring method based on microwave, infrared or equivalent radiation in the winding, in both winding-up and unwinding, for measuring the surface of the machine roll and below the surface. Most suitably, the measurement extends from the surface of the machine roll to a depth in which single web layers change into a roll, advantageously to the depth of about 10-50 mm. According to an additional characteristic of the invention, the measuring depth is defined so that, if required, there is time to perform a flying jointing or a diameter change, i.e. from one second to a couple of minutes. The measurement signal is integrated into a data proc- essing device so that in winding-up is provided a continuous measurement signal from the structure of the machine roll winding-up, of winding quality from the bottom to the surface of the roll. The measurement measures the effect of winding parameters in winding-up and in unwinding is performed a similar measurement in the opposite direction, whereby the measurement also shows the change of the winding structure created by the weight of the web wound inside the machine roll and the deflection of the winding shaft and possible winding defects. The measurement data of winding-up and unwinding is combined so that the corresponding point in the roll comes to the same point in the curve, whereby are obtained the roll structure adjusted with the winding parameters of the winding-up into its own curve and the corresponding machine roll structure realised in unwinding and pos- sible winding defects into their own curve. After this, the measurement compares the measuring results of winding-up and unwinding and aims to provide a correlation between them, whereby in the adjusting system of winding-up can be predicted the structure of the completed machine roll, e.g. define the winding tightness of the roll bottom so that bottom defects are eliminated and the bottom den- sity is suitable. The control system of winding quality can be an expert system, a neural network or fuzzy logic. An intelligent system learns the correlation between the quality measurer of winding-up and the changes and possible defects occurring in unwinding, whereby it is possible to optimise the winding parameters of the windup so that the machine roll remains good in unwinding. The arrange- ment according to this embodiment of the invention can be applied in both the winding-up and unwinding of machine rolls and in the unwinding and winding-up of slitter-winders.

The invention will now be described in more detail with reference to the figures of the accompanying drawing, to the details of which the invention is, however, by no means intended to be narrowly confined.

Fig. 1 schematically shows an embodiment of the invention in which, in connection with winding-up, winding defects are identified from the measurement signal of a pressure-sensitive foil sensor. Fig. 2 schematically shows an embodiment of the invention in connection with an unwinder provided with a nip.

Fig. 3 schematically shows a measuring arrangement applicable in connection with the invention.

Fig. 4 schematically shows an example result of a measurement which aims to predict the burst of a machine roll.

Fig. 5 schematically shows an example result of the integral of the continuous quality measurement of a machine roll.

In the figures and the description related to them, the same references are used of parts corresponding each other if not otherwise stated.

Fig. 1 schematically shows a windup 10 by which a fibre web W is wound into a machine roll 1 1 by means of a winding nip N between a winding drum 12 and the machine roll 11 being formed. Onto the surface of the winding drum 12 is fastened a pressure-sensitive foil sensor 13, e.g. an EMFI sensor, which measures the cross profile of the nip force. From the measurement signal, it is also possible to identify winding defects, e.g. a change of the measurement signal caused by a possible fold V occurring in the web W or an air bag wrinkle IPR caused by an air bag IP in the winding nip formed in the travel of the web W before the winding nip N.

Fig. 2 schematically shows an unwinder 20 in which a fibre web W is unwound from a machine roll 21 in which the web is wound around a winding shaft 22 or equivalent winding core. Into connection with the machine roll 21 is arranged a nip roll 23 which is in contact with the machine roll 21 during the unwinding. In the embodiment shown in the figure, during unwinding, the winding shaft transfers as shown by arrow S so that the contact remains. On the other hand, more commonly in unwinding, the nip roll 23 is transferred so that the contact remains during the unwinding. The fibre web W being unwound is guided to a first lead roll 24 and further to further processing e.g. onto slitter-winders 30. A measuring sensor 25 based on a pressure-sensitive foil is fastened on the surface of the nip roll 23 and, based on the measurement signal given by the sensor 25, it is possible to define possible winding defects and crepe wrinkles etc. possibly created from the inner stresses of the roll in winding-up and in unwinding.

In the schematical example shown by Fig. 3, a measuring system 40 comprises the measuring sensor/sensors 13; 25 arranged into connection with the machine roll 11; 21, e.g. a pressure-sensitive foil sensor, a microwave sensor, an infrared sensor etc., by means of which the surface of the machine roll 11; 21 is measured during winding, winding-up and/or unwinding, and, if desired, a little below the surface, e.g. from the depth of 10-50 mm below the surface. Measuring results are transferred to a computer 41 by means of which the measuring results are analysed, after which, when required, information is conveyed to the winding control system for performing required correction measures, stopping etc. The control system of winding quality can be an expert system, a neural network or fuzzy logic. An intelligent system learns the correlation between the quality measurer of winding-up and the changes and possible defects occurring in unwinding, whereby it is possible to optimise the winding parameters of the windup so that the machine roll remains good in unwinding.

In the example shown in Fig. 4, the processing of measuring data and the identifi- cation of possible winding defects take place either directly observing the measurement signal or by forming a spectre of the measurement signal. The direct measurement signal observation is based on identifying the signal form given by the winding defect and on the continuous comparison of the measured signal with the known signal. In the examination of the spectre, the measuring data of several winding cycles are processed. The possible breaking risk of the roll is aimed to be identified in an as-early-as-possible stage in order to be able to interrupt the proc- ess before the breaking of the machine roll surface. Thus, it is possible to minimise the safety risk and the damages or even eliminate them. In the case of a risk occurring, it is possible e.g. to decrease run speed, to cut the web or to perform an emergency stop.

The example shown by Fig. 5 describes an analysing result obtained in the system according to Fig. 3 in which result the measurement signal is integrated into the data processing device so that in winding is provided a continuous measurement signal from the machine roll being wound. An upper curve 51 depicts unwinding and a lower curve 52 winding-up. On the vertical Y axis is marked a bottom broke limit 53 on the unwinder and a bottom broke limit on the windup 54. The horizontal X axis describes the diameter of the roll. The measurement measures the effect of winding parameters in winding-up, whereby is obtained a measuring result on the structure of the machine roll, of the winding quality from the bottom to the surface of the roll. In unwinding is performed a similar measurement in the opposite direction, whereby the measurement also shows the change of the winding structure created by the weight of the web wound inside the machine roll and the deflection of the winding shaft and possible winding defects. The measurement data of winding-up and unwinding can be combined so that the corresponding point in the roll comes to the same point in the curve, whereby are obtained the roll structure adjusted with the winding parameters of the winding-up into its own curve 52 and the corresponding machine roll structure realised in unwinding and possible winding defects into their own curve 53. After this, the measurement compares the measuring results of winding-up and unwinding and aims to provide a correlation between them, whereby in the adjusting system of winding-up can be predicted the structure of the completed machine roll, e.g. define the winding tightness of the roll bottom so that bottom defects are eliminated and the bottom density is suitable. The invention was described above only referring to some of its advantageous embodiments, to the details of which the invention is, however, by no means intended to be narrowly confined.

Claims

1. A method in connection with a winder of a fibre web, in which method, the fibre web (W) is wound up and/or unwound and a characteristic affecting and/or forming in the winding of a fibre-web roll (11 ; 21) being wound is measured by at least one measuring sensor (13; 25), characterised in that, in the method, measuring results are processed for detecting a sudden change occurring on the periphery of the fibre-web roll (11; 21) in the machine direction for detecting and identifying pulse-like winding defects for defining and controlling the inner quality and structure of the fibre-web roll (11; 21).

2. A method according to claim 1, characterised in that, in the method, measuring results are processed for detecting a sudden change occurring at most during one winding cycle.

3. A method according to claim 1 or 2, characterised in that in the method is measured a characteristic affecting and/or forming at most in one cycle as the roll rotates.

4. A method according to any one of claims 1-3, characterised in that, in the method, a measuring sensor/sensors (13; 25) is/are located onto the surface of a roll (12; 23) or equivalent arranged into nip contact with the roll (11; 21) being wound.

5. A method according to any one of claims 1—4, characterised in that, in the method, as a measuring sensor/sensors is/are used sensors of pressure-sensitive foil and the profile and advantageously the nip force profile of the roll is measured and from the measuring results are obtained information on sudden changes occurring in the profile which changes indicate roll damages and the start of the breaking of the roll.

6. A method according to any one of claims 1-3, characterised in that a non- contacting microwave radar or laser sensor is used as the measuring sensor/sensors.

7. A method according to any one of claims 1-6, characterised in that, in the method, into connection with winding is formed a measuring system (40) by means of which the measurements are performed and the measuring results are processed and from which the measuring results are conveyed to the control system of winding.