JP4718482B2 - Method for controlling operating parameters in an apparatus for processing a fibrous web and apparatus for providing the method - Google Patents

Description

  The present invention relates to a method for controlling operating parameters in an apparatus for processing a fibrous web, the processing apparatus comprising an endless metal belt arranged to rotate around a guide means, a metal belt and a contact surface. A treatment zone for the fibrous web is formed between the metal belt and the opposite element, and the fibrous web to be treated passes through the treatment zone.

  The invention also relates to an apparatus for controlling operating parameters in an apparatus for processing fibrous webs, the processing apparatus being in contact with the endless metal belt arranged to rotate around the guide means, and the metal belt. A treatment zone for the fibrous web is formed between the metal belt and the opposite element, and the fibrous web to be treated can pass through the treatment zone. .

  The invention further relates to a method for measuring the temperature of a belt in an apparatus for processing a fibrous web and for controlling the process, the processing apparatus being arranged endlessly arranged to rotate around guide means. A metal belt and at least one opposing element forming a contact surface with the metal belt, between which the treatment zone for the fibrous web is formed and the fibrous material to be treated The web passes through the processing zone.

  The invention also relates to an apparatus for measuring the temperature of a belt in an apparatus for processing a fibrous web and for controlling the process, the processing apparatus being arranged endlessly arranged to rotate around guide means. A metal belt and at least one opposing element forming a contact surface with the metal belt, between which the treatment zone for the fibrous web is formed and the fibrous material to be treated The web passes through the processing zone.

  Furthermore, the present invention provides a narrow tail threading cord that allows the fibrous web to be controlled by controlling the temperature profile and tensile stress of the belt of a metal belt calender intended to treat the fibrous web during threading of the fibrous web. It relates to a method for moving a metal belt having a higher temperature in contact with it, thereby providing a cooling effect to the metal belt. The invention further relates to an apparatus for providing the method.

  This type of equipment for processing fibrous webs has been known for some time, for example from the applicant's patent applications PCT / FI03 / 00066, PCT / FI03 / 00067, PCT / FI03 / 00068. The equipment for processing the fibrous webs disclosed in these applications is the calendering of very different types of fibrous webs, such as different paper and paperboard grades, as well as coating, film transfer, drying and / or printing. Applies to Further, the belt used in the apparatus for processing the fibrous web disclosed in said patent application is optimally a metal belt or metal wire, but may be a polymer or composite wire or cord or the like. . The specification of this patent application refers to a metal belt as an example, but is not limited thereto.

  The effect of processing by the equipment for processing the fibrous web referred to above applying belt circulation on the final properties of the fibrous web is the effective compression in the processing zone, the processing humidity of the fibrous web, and the contact It is controlled by adjusting the processing conditions in the processing zone, such as the effective time of. In practice, these adjustment means are accomplished by adjusting the temperature of the actuators acting on the fibrous web, for example the belt and / or the counter element or the length of the treatment zone and / or the treatment time or the belt tension. .

  The adjustment means performed to control the process may be based on, for example, an experimentally determined target value of the actuator control variable. For example, pilot test runs determine the optimum roll and web temperature, as well as the effective zone pressure and effective time for each fibrous web grade. The goal is to adjust the actuator control variables to preferred values and keep them at these target values when the process is in the standard state. However, in order for the actuator adjustment to function correctly and the setpoint to be maintained at the target value, the operation of the actuator must be controlled. For example, belt temperature and tension must be measured directly or indirectly, and if necessary, the process must be adjusted to function continuously as well.

  Adjustments can also be based on feedback online process measurements. In that case, on-line measurement of the fibrous web is used as a basis for conditioning. If the observed treatment effect does not correspond to the target condition, the adjustment system changes the actuator settings, such as belt or web temperature or belt tension, so that the target level is achieved. Furthermore, it should be possible to control the actuator state accurately and without delay, if it is desired to maximize the output that satisfies the quality criteria during a transient change in the process. Also, in this case, measurements such as belt temperature can be used to control the state of the actuator itself and as the basis for the adjustment means. In order to compensate for the actuator to be adjusted, a situation where variables originating from the initial process stage cause disturbances in the treatment process can be mentioned as an example, but it is desirable to standardize the final quality produced.

  One problem is raised by the edge zone of the metal belt, in which case the thickness varies specifically as a result of possible temperature fluctuations. This can have a degrading effect on the quality of the fibrous web. In addition, as the service life increases, the belt edge thickness, in particular, does not necessarily remain the same as the initial value due to belt material wear (metal fatigue) and damage to the belt material.

  By observing the above properties, no information about the wear of the metal belt is obtained, and therefore no direct information about its effect on the quality of the web. There is no reliable, especially essentially continuously operating structure for measuring the thickness of a metal belt. The measuring method in contact with the surface is not suitable for measuring the thickness and the optical instruments are easily contaminated in an unclean environment. Methods using radiation sources such as those that emit X-rays cannot be used for continuous monitoring of belt thickness under any circumstances due to their hazard (radioactivity).

  Measurement of the temperature on the surface of a moving belt having a glossy surface is also not possible at this time in a very reliable manner under normal production conditions. In principle, a number of different temperature measurement techniques are known. The temperature of the moving belt can possibly be measured by a non-contact technique such as, for example, a contact (dragging) temperature sensor or a thermographic camera (IR measurement).

  The problem with non-contact infrared measurement is that the surface of the hot roll or belt that contacts the fibrous web is polished and finished to produce a good fibrous web. From a thermographic camera measurement perspective, the low emission coefficient of the polished surface and the reflection from the surroundings are problems. Even slight contamination of the surface can greatly affect the emission factor and cause measurement errors. Even in a laboratory environment, thermographic cameras must be calibrated on a daily basis in practice, so this type of solution is subject to the conditions of industrial plant types that require high reliability and low maintenance. Is not applicable. On the other hand, in principle, contact (dragging) temperature measurement can also be used in manufacturing conditions. However, due to the high speed, the results of contact measurements are unreliable and the measuring instrument requires constant maintenance and repetitive calibration. Excess heat from sliding friction also hinders measurement.

  Further, for example, in metal belt calenders where the opposing element is a heated roll heated, one problem is that when there is no fibrous web to be processed in the processing zone between the steel metal belt and the heated roll, they are interlinked. To come into contact. Thus, when the hot roll is heated, for example, during web shut-off, the belt guide roll is in liquid circulation, eg water or heated oil, to cool the belt and maintain the belt temperature profile linearly. The heat can be transferred from the hot heat roll to the belt. The temperature of the heated oil used inside the hot roll is, for example, on the order of about 300 ° C., whereby the surface of the hot roll is about 250 ° C. and when there is no web to be processed between them, The belt that comes into contact rises in temperature to about 200 ° C. As soon as the web is brought into the processing zone and normally travels between the hot roll and the belt, the surface temperature of the hot roll is in the range of about 150-200 ° C, depending on the properties and temperature of the incoming web. To descend. If the metal belt is not heated, it essentially reaches the temperature of the web at operating conditions.

  When guiding the web to the processing zone of the metal belt calender, for example, a narrow tail threading cord cut from a fibrous web having a width of 100-300 mm is first brought into the calendering zone. This greatly cools the metal belt with a cord. As the belt cools over a narrow zone on one edge, it becomes shorter and this zone begins to receive the belt's stretching force, thereby creating a high traction force on the edge. This asymmetry probably affects the controllability of the belt. As a result, the fatigue durability of the belt is reduced. In addition, in a solution where no cooling liquid circulation is arranged in the guide roll of the belt cycle, the belt and the leading roll of the belt will rise to near the temperature of the hot roll, so that after the web has spread, the belt temperature It takes a fairly long time, e.g. 10 minutes or more, before the temperature drops essentially to the temperature of the web and the hot belt no longer affects the bulk.

  The object of the present invention is to eliminate or substantially reduce the disadvantages mentioned above and thus better control the operating parameters in the apparatus for treating the fibrous web.

  To achieve the above object, the method according to the first aspect of the present invention is characterized in that the metal belt thickness measurement is performed by eddy current measurement during operation.

  In addition, the device applying the method according to the first aspect of the invention is characterized in that it comprises measuring means capable of measuring the thickness of the metal belt by eddy current measurement during operation.

  The method according to the first aspect of the invention is a system in which the measurement of the properties of the fibrous web is carried out by the measuring means during operation, and the information relating to the properties of the fibrous web controls the quality of the fibrous web. And the information on the properties of the fibrous web is used as feedback and / or positive feedback information for other operating parameters that control the quality of the fibrous web.

  The apparatus applying the method according to the invention comprises measuring means capable of measuring the properties of the fibrous web during operation, the measuring means being connected to a system for controlling the quality of the fibrous web, Information regarding the characteristics of the web can be used as feedback and / or positive feedback information for other operating parameters that control the quality of the fibrous web.

  One method according to the invention is characterized in that the temperature of the belt is measured in a non-contact manner during the run from the opposite side of the belt to the fibrous web. Furthermore, the device applying the method according to the second aspect of the invention comprises a measuring means capable of measuring the temperature of the belt surface in a non-contact manner from the opposite side of the belt to the fibrous belt during operation. It is characterized by including.

  A further method according to the invention is that the metal belt is cooled with a cooling medium at a point outside the area where it contacts the tail threading cord in order to obtain an essentially uniform temperature profile for the metal belt. It is characterized by. On the other hand, the device according to the invention cools the metal belt with the cooling medium at a point outside the area where the cooling medium contacts the tail threading cord in order to obtain an essentially uniform temperature profile for the metal belt. It is characterized by including these means.

  Preferred embodiments of the invention are disclosed in the dependent claims.

  The present invention will now be described in detail with reference to the accompanying drawings.

  FIG. 1 thus shows part of an apparatus for applying the method according to the invention. The part of the device indicated here by reference numeral 1 is in this case a belt calender used to process a fibrous web W, such as paper or paperboard, in order to obtain the desired quality. The apparatus is, for example, a paper machine or a paperboard machine.

  The calendar 1 includes an endless belt made of a conductive material, preferably a metal or metal alloy. The metal belt rotates on a track around the guiding means, at least one of the guide rolls being movable to adjust the tension of the belt 2. The tension of the metal belt 2 is one of the operating parameters of the device that controls the processing of the fibrous web W on the calendar 1.

  On the outside of the loop-shaped track formed by the belt 2, an opposing element 5 including an opposing surface that can be arranged with respect to the metal belt is arranged. The facing element 5 is preferably a backing roll and is arranged so that the belt 1 travels around its mantle. The belt 1 is in contact with the mantle, preferably over a distance corresponding to less than half the full length of the outer circumference of the mantle. A treatment zone A, in this case a calendering zone, is formed between the belt 1 and the mantle, through which the fibrous web W passes. Next, the desired pressure impulse and thermal effects (operating parameters) as a function of time are applied on the fibrous web. The possibility of adjusting these is disclosed in more detail in the applicant's prior patent applications PCT / FI03 / 00066, PCT / FI03 / 00067, PCT / FI03 / 00068. Briefly, for example, the pressure can be adjusted by a nip roll 4 that forms a nip with a backing roll, and the thermal effect can be adjusted by heating and cooling the metal belt 1 using a heating and cooling device 6; The metal belt 1 is profiled in the lateral direction. The adjustment of the belt 1 temperature also affects the lateral distribution (stress distribution) of the tension in the machine direction of the belt. Changes in temperature and pressure in processing zone A change the thickness profile of the metal belt in the transverse direction. On the other hand, changes in the transverse thickness profile cause changes in the properties (eg thickness and gloss) of the fibrous web.

  According to the invention, in order to monitor the change in the thickness of the metal belt 2, the device 1 includes means 7a, 7b for measuring the metal belt thickness, by means of which the longitudinal direction of the metal belt 2 is measured. The thickness profile and / or the lateral thickness profile of the metal belt is measured. The measuring means 7a, 7b include measuring instruments that apply eddy current methods known as such. In this case, at least one such measuring device is arranged in the vicinity of the surface of the metal belt 2, for example in the region between the two guide rolls 3. The measuring means 7a, 7b include at least one electromagnetic transmitter, such as a coil 7a, and on the opposite side of the metal belt 2 is a receiver, such as a measuring coil 7b, between which the metal belt 2 runs. To do. Measuring devices 7a, 7b may be arranged so that the fibrous web travels with the metal belt 2 between the receiving coil 7a and the measuring coil 7b (the measuring device is depicted in broken lines). Since the fibrous web is non-conductive, it does not affect the thickness measurement of the metal belt 2 performed by the eddy current measurement method.

  Briefly, the measurement is preferably performed by using a pulsed eddy current measurement technique. Among them, the transmitter coil 7a is used to form a three-phase magnetic field in the conductive belt 2, whereby eddy currents are also induced in the belt 2 in three different phases. From each successive phase, the voltage characteristic of each phase is induced in the measuring coil 7b. From them, the distance of the measuring coil 7b from the surface of the metal belt 2 to be measured, the electrical resistance of the material to be measured and the thickness of the metal belt 2 can then be determined.

  It is possible to adapt the measuring device 7a, 7b or several measuring devices 7a, 7b described above to move transversely to the direction of travel of the belt 2. Alternatively, a sufficient number of measuring instruments 7a, 7b can be fitted in a row with respect to the direction of travel of the belt 2, whereby a more detailed measurement result is obtained compared to a moving measuring instrument. Measurements can be performed while the metal belt 2 moves essentially continuously.

  The measurement data obtained on the thickness of the metal belt 2 can be used for several purposes. This data can be incorporated into a system 10 for controlling the quality of the fibrous web W, which includes, among other things, control devices 6 and 4 for operating parameters such as belt 2 temperature and process area A pressure impulses. Information about the thickness of the belt 2 and the changes that occur therein can be obtained, for example, in real time from the measuring coil 7b to the system that controls the quality of the fibrous web W along the transmission path 8 between the system 10 and the measuring coil 7b. It is obtained by. Thus, for example, changes in the belt edge zone thickness profile can be monitored in relation to different loads and temperature changes.

  The change in the quality of the fibrous web W due to the change in the thickness of the belt is compensated by using the thickness data for the belt 2 as a positive feedback for other parameters that control the quality of the fibrous web W. The measured data can be used in the system 10 for controlling the quality of the fibrous web W. For example, a control command may be provided from the control system 10 to the profiling heating and cooling device 6 of the belt 2 along the transmission path 9. Profiling heating or cooling can be controlled so that the thickness profile of the belt 2 is of a desired type, for example uniform. It is also conceivable to control the tension profile of the belt 2 by controlling the thickness profile. In addition to the calendar, the quality control system 10 is obviously connected to other parts of the device 1 (here, the paper machine), so that the thickness data is the other of the device 1 that controls the quality of the fibrous web W. It can also be used as positive feedback data for partial operating parameters.

  A model can also be formed from the effect of the change in the thickness of the belt 2 on the quality of the web W, and based on the model, the quality control system 10 makes the necessary compensation adjustments to the parameters that control the quality.

  Measurement data can be used to monitor the quality of the belt 2 itself. For example, before its actual start-up, the belt 2 is ground to an appropriate thickness. Measurement data relating to measurements prior to polishing can be used to set up the polisher to obtain the correct thickness profile for the belt 2. Furthermore, for example, changes in the tension and temperature of the belt 2 will soon cause damage to the belt, particularly in the edge zone of the belt 2. These defects are observed when they are just right considering other parameters of the quality control system. Based on the observation, for example, the belt 2 can be changed at the best time.

  FIG. 2 thus shows an apparatus 1 for applying the method according to the second aspect of the invention. Here, the apparatus is a metal belt calender used to treat the fibrous web W in order to provide the desired treatment effect. The device can also be some other processing device such as a drying device, a film transfer device, a printing device and the like. The belt calendar 1 is installed in, for example, a paper or paperboard production line as an online device, or it operates independently as an offline device. The device 1 comprises an endless belt 2 made of metal, which rotates around a guide roll 3, at least one of which is movable to adjust the tension of the belt 2. On the outer side of the loop-shaped track formed by the belt 2, an opposing element 5 including an opposing surface that can be arranged with respect to the belt is arranged. The counter element 5 is preferably a backing roll and is arranged so that the belt 1 runs around its mantle. The backing roll is preferably a hot roll.

  A treatment zone A is formed between the belt 2 and the roll 5 mantle, and the fibrous web W to be treated is fed therethrough. The desired pressure impulse and thermal effect is then applied on the fibrous web W as a function of time. The possibilities for adjusting the processing parameters effective in processing zone A are described in more detail in the applicant's prior patent applications PCT / FI03 / 00066, PCT / FI03 / 00067, PCT / FI03 / 00068, It is not described in more detail in this connection.

  For example, the nip roll 4 that forms the nip N with the backing roll 5 can adjust the pressure of the process zone / pressure impulse in the process zone in addition to belt tension. By heating and cooling the belt 2 with its heating and cooling equipment 6a, the thermal effect in the processing zone can be adjusted, which can be lateral profiling. Similarly, the guide means 3 can supply heat to the metal belt or remove the heat. By controlling the temperature of the belt 2, the lateral distribution (stress distribution) of the machine direction (MD) tension of the belt is also affected.

  According to the present invention, to measure the temperature of the belt 2, the device 1 includes means that can measure the temperature of the belt 2 to indicate the longitudinal and / or transverse temperature profile. The measuring means 70 comprises a temperature sensor applying a non-contact measuring technique known as such, for example an infrared technique which can be either a point measurement or a so-called line scan sensor. In this case, at least one such temperature sensor is located in the vicinity of the surface of the belt 2, for example, preferably in the region between the two guide rolls 3. The temperature sensor 70 may preferably be located in front of the processing zone A and / or also behind the processing zone. Furthermore, if the cooling / heating device 6a, 6b is used to cool and / or heat the belt 2, the measuring device 70 can be located in front of and / or behind the cooling / heating device 6a.

  The surface of the belt 2 in contact with the fibrous web W is finished and polished to achieve the quality characteristics of the fibrous web, which means that it is not suitable for measurement by a thermographic camera. In the method according to the invention, this problem is preferably solved by measuring the temperature on the inside of the belt cycle, ie on the “opposite” side with respect to the fibrous web W. Since the metal belt 2 is very thin (usually on the order of about 1 mm or less), the average temperature of the belt can be obtained with good accuracy by performing measurements on the other side of the belt. The emissivity of this side of the belt 2 can be set so that infrared thermal measurements can be performed successfully. The belt can be polished, for example, to have a matte finish. It was found that when in contact with the metal roll 3, the surface of the belt 2 was not polished and remained "rough".

  According to one embodiment of the invention, the temperature measurement is performed over the entire width of the belt so as to obtain a temperature profile transverse to the belt.

  According to a further embodiment of the invention, it is possible to perform the measurement by applying synchronization so that the measurement is always performed at the same point in the longitudinal direction on the belt cycle 2, so that the temperature of the belt 2 can be set as desired. Can be determined accurately at the longitudinal position.

  The method according to the invention is also applicable to the temperature measurement of the metal belt 2 when a polymer coating or the like is used for the belt 2, especially on the side of the fibrous web W. Furthermore, the method according to the invention is also reliable when dirt adheres to the fibrous web side of the belt or when the surface roughness changes as a result of wear.

  The measurement data obtained by the present invention can be used for several purposes. For example, the measurement data obtained can be used to control the processing process of the fibrous web W (by controlling belt heating and profiling) or by controlling the running of the belt cycle. The data may be sent to a system 10 for controlling the quality of the fibrous web W, which includes, for example, a belt temperature control means 6a, a control means 6b for controlling the temperature or humidity of the fibrous web, a backing roll temperature control. Means 5, compression force control means 4, or control means 3 for controlling the position of the guide roll is included (belt tension). The system further includes measuring means 13a, 13b for monitoring the state of the fibrous web (temperature, humidity, quality, gloss, etc.). Information regarding the temperature of the belt 2 and the changes that occur therein may be transmitted to the system 10 in real time along the transmission path 12 between the system 10 and the measuring instrument 70.

  The most common use of the belt temperature measurement 70 is to use the measurement as part of a belt temperature feedback control. In this case, the actual temperature of the belt is monitored using measurement sensor 70, and if this temperature deviates from a given target temperature, controller 10 receives the measurement signal received until the target temperature is reached. The actuator 6a is controlled based on the above. The target temperature can be preset, for example by pilot testing. The target temperature of the belt is obtained in real time from an on-line quality control system so that the controller can determine the preferred process temperature (belt temperature) based on the quality measurement (13a, 13b) of the fibrous web. Thus, belt temperature control acts as part of a broader control system.

  The essential application for controlling the running of the belt cycle is to use the measurement signal 70 to control the belt. The belt temperature profile inevitably produces a tension profile through thermal expansion, which has a significant effect on the running of the belt cycle. From the measured temperature profile, a transverse (CD) profile of the machine direction tension of the belt can be estimated. The running of the belt cycle is controlled mainly by adjusting the position of the guide roll 3, so that this adjustment can be based on temperature measurements.

  At a more general level, other measurement process variables related to the broader control system and changes therein can be quickly transmitted to the system 10. Therefore, in addition to the belt 2 temperature measuring device 70, the web quality control includes means 13a, 13b for measuring the state of the fibrous web, actuators 3, 4, 5, 6a, 6b, and the quality control system 10. It is configured by positive feedback including (controller) and / or feedback control. Thus, each actuator operating under quality control is quickly controlled by the controller based on quality measurements such as belt temperature measurements. Control may be based on a model, for example. Controllable actuators are listed above, and controlled variables or operating parameters controlled by them include, for example, web input temperature and humidity, belt tension, belt temperature, belt humidity, overlap angle and belt length, additional It can include the temperature of the load (nip roll 4) and the hot roll (ie, roll 5).

  Of course, the adjustments described above can relate to either the average target value or the measurement value in the lateral direction, and the adjustment can take into account variations in the measurement value and controlled variables, in other words, the profile is measured And adjusted.

  Furthermore, the temperature variation of the belt 2 in the longitudinal direction (MD) of the belt can be observed particularly by the method according to the invention. By appropriately synchronizing the measurement acquisition with the belt cycle length, the measurement position can be changed in a controlled manner to a desired point on the belt in the machine direction. In this way, periodic process defects at the belt temperature, such as local contamination of the belt or heat transfer roll, that reduce the heat transfer coefficient can be found.

  To adjust the machine direction temperature profile of the belt, the machine direction temperature profile measurement data can also be used to control a rapid heating actuator, such as an induction heater (eg, at position 6a).

  One possible application of the present invention may be the measurement of heating / cooling effects transmitted through a belt. By positioning the temperature sensor on both sides of the processing zone, the thermal energy transferred between the belt and the fibrous web can be easily calculated from the temperature difference. The measurement data can be used to adjust the cooling / heating effect on the belt 2 and thus to help process control to adjust the processing temperature, particularly in processing zone A. The measured data can also be used in systems that monitor energy usage.

  Furthermore, according to the embodiment shown in FIG. 3, the metal belt calendar 1 includes a metal belt 2 arranged to rotate the guide roll 3. On the outside of the belt, a heat roll acting as the counter element 5 is arranged, and thereby a calendering zone is formed between the belt 2 and the roll 5. Contact between the belt 2 and the counter element 5 for the purpose of adjusting the belt 2 to the desired tension and, if necessary, for example by changing the overlap angle between the roll 5 and the belt 2 In order to adjust the length of the region, it is preferable that at least a part of the guide roll 3 is movably arranged. Inside the belt cycle 2, a nip roll 4 that acts as a pressing means for pressing the belt 2 against the roll 5 is selectively arranged, so that the highest pressure can be generated in the calendering zone of the nip zone.

  According to the invention, a metal belt cooling device 6a comprising a cooling medium diffusing means 6a is arranged in the metal belt calendar 1 so that a cooling medium, for example air or water, is delivered to a desired point on the metal belt 2. Get turned. The cooling medium diffusing means 6a is preferably arranged to be movable in the lateral direction of the metal belt, as shown in FIG. 4, but they may have several lengths extending across the width of the metal belt 2. It may consist of a spray nozzle or similar means, whereby the supply of cooling medium can be directed to different points across the width of the metal belt 2 in the desired manner. The cooling medium diffusing means 6a is preferably arranged outside the metal belt cycle 2 at a point in front of the calendering zone, as shown in FIGS. 1 and 2, but they are located at a point behind the calendering zone. It is also conceivable that it is located at a point in front of or behind the calendering zone within the metal belt cycle.

The basic idea of the present invention is to make the temperature profile as linear as possible and to tailor the prevailing tensile stress at different points in the lateral direction of the belt to increase the fatigue durability of the belt, the tail threading cord W ₁ The metal belt is cooled in the outer region. When water is used as the cooling medium, for example, and when the belt temperature exceeds 100 ° C., the water sprayed onto the belt surface evaporates essentially immediately, which is similar to the water evaporating from the web after the nip. Can be recovered using air conditioning.

  This type of orientation of the cooling medium on the metal belt is used to achieve a more uniform quality for the paper or board grade being processed, especially when the normal operating temperature of the belt is significantly lower than that of the hot roll. Useful. If this type of cooling is used, if no coolant cycle is in place, both the belt and the belt guide roll will rise to near the temperature of the hot roll so that after web diffusion, the belt temperature. It will take a considerable amount of time before it essentially drops to the temperature of the web.

  For example, in order to make the thermal profile essentially linear, the coolant spray is preferably arranged to be profiled so that the coolant spray is directed only to the highest temperature point of the metal belt.

Fig. 2 schematically shows a side view of some embodiments of the device according to the invention. FIG. 6 is a side view schematically showing another embodiment of the device according to the invention. FIG. 6 is a side view schematically showing a third embodiment of the device according to the invention. It is a top view which shows arrangement | positioning of FIG.

Claims (19)

A method for controlling operating parameters in an apparatus for processing a fibrous web,
The processing apparatus includes a belt arranged endless to rotate around the guide means, at least one counter-element forming a contact surface with the belt, between the belt and the counter element, A treatment zone for a fibrous web is formed, the fibrous web to be treated passing through the treatment zone,
The belt thickness is achieved by eddy current measurement during operation ,
The temperature of the belt is measured in a non-contact manner from the opposite side of the belt to the fibrous web during operation.
Information regarding the thickness of the belt is incorporated into a system for controlling the quality of the fibrous web, and information regarding the thickness of the belt is for other operating parameters that control the quality of the fibrous web. Used as positive feedback information,
Information regarding the temperature of the belt is incorporated into a system for controlling the quality of the fibrous web, and information regarding the temperature of the belt is positive feedback for other operating parameters that control the quality of the fibrous web. Used as information,
Method. The method of claim 1, wherein the belt is measured essentially continuously to determine a longitudinal thickness profile. 3. A method according to claim 1 or 2, characterized in that the belt is measured essentially continuously to determine a lateral thickness profile. Information about the thickness of the pre-Symbol belt, characterized in that it is used as a positive feedback information for monitoring the state before Symbol belt A method according to any one of claims 1 to 3. An apparatus for controlling operating parameters in an apparatus for processing a fibrous web;
The processing apparatus includes a belt arranged endless to rotate around the guide means, at least one counter-element forming a contact surface with the belt, between the belt and the counter element, A treatment zone for the fibrous web is formed, the fibrous web to be treated being equipment that can pass through the treatment zone,
By eddy current measurement in between 稼働期viewing including the thickness measuring means capable of measuring the thickness of the belt,
Temperature measuring means capable of measuring the temperature of the belt in a non-contact manner from the opposite side of the belt to the fibrous web during operation;
The thickness measuring means is connected to a system that controls the quality of the fibrous web, and the information about the thickness of the belt is positive feedback information for other operating parameters that control the quality of the fibrous web. Can be used as
The temperature measuring means is connected to a system that controls the quality of the fibrous web, and information about the temperature of the belt can be used as positive feedback information for other operating parameters that control the quality of the fibrous web Is,
machine. In order to determine the longitudinal and / or transverse thickness profile of the belt , one or more thickness measuring means are adapted to move transversely with respect to the direction of travel of the belt. The device according to claim 5, characterized in that: In order to determine the longitudinal and / or lateral thickness profile of the belt, several thickness measuring means, characterized in that it is adapted transversely to the traveling direction of the belt, wherein Item 5 or 6. The thickness measuring means comprises: an electromagnetic transmitter or coil capable of forming a three-phase magnetic field for inducing eddy currents in three different phases on the belt ; and a receiver in which a voltage corresponding to the eddy currents is induced or The device according to claim 5, further comprising a measuring coil, wherein the eddy current correlates with the thickness of the belt . Information about the thickness before Symbol belt is characterized by a state before Symbol belt may have use as a positive feedback information for monitoring, device according to any one of claims 5 to 8. In order to determine the longitudinal temperature profile of the belt is characterized in that it is essentially continuous measuring method according to claim 1. To determine the lateral temperature profile of the belt is characterized in that it is essentially continuous measuring method according to claim 1. Wherein as the temperature of the belt is obtained at a specific point, the temperature is characterized in that it is measured in a synchronous manner, the method according to claim 1. The method of claim 1 , wherein the measured temperature is used as feedback to adjust the temperature of the belt. Information about the temperature of the belt, is incorporated within the system to control the process, information regarding the temperature of the belt is used to monitor the state of the belt as well to control the operation of the belt cycle 14. The method according to any one of claims 1, 10, 11, 12, and 13 , characterized in that 15. The belt according to any one of claims 1 to 4 and 10 to 14 , characterized in that a metal, polymer or sandwich belt, wire, felt or the like is used as the belt. Method. In order to determine the longitudinal and / or transverse temperature profile of the belt, one or more measuring means are arranged to be movable essentially transverse to the direction of travel of the belt. The device according to claim 5 , wherein 6. An apparatus according to claim 5 , characterized in that one or more measuring means are arranged continuously in the direction of travel of the belt and measure the temperature difference between these points. Information about the temperature of pre-Symbol belt, characterized in that it is available to monitor the state before Symbol belt, claim 5, 16, and 17 apparatus according to any one of. 19. Device according to any one of claims 5 to 9 and 16 to 18 , characterized in that the belt is made of metal, polymer, or sandwich type, wire felt, or the like.

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