FI121020B - Method and arrangement for cutting off the supply of treating agent in the manufacture of paper or board - Google Patents

Description

The present invention relates to a method and arrangement for rapidly cutting off the feed material of a coating, adhesive or other processing agent during driving in the manufacture of paper and board.

10 A rapid cut-off of the treatment agent feed is required to temporarily stop the coating or other treatment. In particular, rapid interruption can be used to reduce web breaks in a paper or board machine in which the bottom web production and at least one coating step and calendering take place on-line, i.e. without interrupting or unwinding the web.

In order to improve efficiency and cost-effectiveness in coated paper grades, solutions have been adopted in which bottom web production (paper machine) and coating (coating / surface sizing unit) and calendering (one or more calendars) work in a so-called line. as an on-line machine. The manufacture of cartons is generally done in this way. Such a line is characterized in that 25 webs run continuously throughout the production line and are not cut and rolled for storage for various operations. This approach is highly productive, but the risk of line breaks is always increasing as the complexity of the machine line increases and so does the cost of production interruptions due to line breaks. In addition, paper machines, coaters, and calendars have different characteristics that can sometimes make it difficult to fit in the same line. However, especially for LWC-2 species, on-line film transfer coating has displaced off-line coating on non-gravure types. For some of the new machine lines, final calendering is also done online.

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Fault detectors and defect analysis techniques have advanced in the 21st century to the point where paper web defects can be seen and analyzed in real-time on a moving web. On the other hand, labor costs and the advancement of 10 paper machine technologies are driving the production of ever more demanding grades for All-on-machine type paper machines with film coating, blade coating and final printing all on the same paper machine line without intermediate rolls. Such a machine is very efficient but also very vulnerable to breakages in coating and calendering. It is clear that production losses due to production disruptions on such machine lines are also costly due to the high production speed and high value added of the product.

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The proliferation of on-line systems for heavier coated fine papers has been slowed down by the smoothness and coating requirements of the final product, which require blade coating. Because of the importance of breaks in on-line 25 systems, blade coating is less suited to on-line concepts due to its susceptibility to breakage.

The so-called papermaking line. at the dry end, that is, after the desiccant group, production-reducing interruptions occur mainly due to holes in the base paper and bottom edge defects. Blade coating stations are particularly sensitive to hole breaks because of the high forces exerted by the doctor blade on the web. Of the blade coating stations, so-called "break breaks" are best tolerated. short-dwell stations with 3 doctor blades or rods defining the application chamber. The holes in the bottom web may already lead to tearing of the web and uncontrolled web break at the coating station. Line breaks can also occur due to blows used to control the web, and the paper fins on the edges of the holes easily enlarge the holes in the paper so that a break occurs.

The holes are also a barrier to the proliferation of on-line final calendering after blade coating. If the hole-10 hand gets through the blade station, the excess coating build-up around the hole will soil the calender rollers. Particularly at the opening edge of the hole, the coating is depressed by a doctor blade on the backside of the web, from where it moves to the calender rolls or may even cause them to sink. Similarly, when using metal belt calendars, there is the problem that a hole or edge failure in the web may create a filler spot in the paper or board to be made from the surface glue or coating if the hole is small enough. The elastic properties of the fill position differ significantly from the other 20 tracks. When the seat enters the nip of the metal belt calender, the stroke received by the belt is so great that impact on the belt is possible. Partially non-drying coating material may also adhere to the hot belt. Often the grip is so tight that it cannot be removed with a scraper cleaning strap. If the grip re-enters the strap, the surface of the strap may be damaged at this point. At least the surface of the product being manufactured will be damaged.

The malfunctions described cause difficulties for most of the 30 calender types, but the degree of malfunction of the malfunction type differs slightly according to the calender type. For these reasons, on lines using sequential blade coating and calendering, the web is typically cut to protect the calender rolls if a hole is detected in the web. The holes are detected by a defect detector that examines the quality of the web being manufactured. One method of protecting calender rolls is described in Finnish Patent 106966B.

5 Blade coating defects are often the cause of web breaks. These are, of course, detrimental to all manufacturing and all production lines, both on-line and off-line, but the more complex the production line, the more significant they become 10. Edge defects include holes, pleats and stickers, and other irregularities at the edge of the web that can cause tearing when entering the doctor blade. Errors at the edge of the web are particularly significant because they are more likely to cause breakage than errors at the center of the web. Edge defects also run the risk of aggravating the roller blades or pleats with the scraper blade and more likely to damage the calender rollers.

20 A particular problem with off-line systems is the passage of the seams on the roll (if any) through the overlay. The seam site presents a risk of breakage when it is typically run through the overcoat at normal production speed while the overcoat is operating. In order to avoid the risk of holes and edge defects, off-line machines use intermediate roll, allowing holes and other defects to be patched or repaired. The idler is an expensive device and its use causes costs that would be advantageous to avoid.

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Possible ways to deal with the disruptions described above are disclosed in our co-pending patent application FI 20085105.

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From the foregoing, there is thus a clear need for an arrangement whereby the feed material for the coating or surface sizing stations can be quickly stopped so that the disturbance situation can be reacted without interruption.

It is an object of the present invention to provide a method and arrangement by which the supply of coating, surface adhesive or other treatment agent to a blade coating, short-stay, jet, spray or other applicator can be interrupted rapidly.

In particular, it is an object of one embodiment of the present invention to provide a method by which the feed of the treatment agent can be interrupted without opening the return cycle.

More particularly, the process of the invention is characterized by what is disclosed in the independent claims.

The invention provides considerable advantages.

The main advantage of the invention is that the efficiency of the machine line is significantly improved when the hole breaks in the blade stations and the roll shield breaks in the fish blade can be reduced or even minimized. In addition, one major obstacle to an effective dual-coated on-line concept can be removed. The invention provides a fast and web-free opening / restart sequence for the coating portion of an all-on-machine paper machine so that critical machine components can actively respond to the failure information provided by the fault detector in the most efficient time-machine manner possible.

The invention is practicable without major modifications to existing systems.

Without the high-speed and optimally positioned auxiliary valves of the present invention, most current on-line blade coating machines do not allow cut-off material to be cut off fast enough to open the position at the hole. There is really little time for this procedure on some machines when the first possible position of the fault indicator after the pre-dry tenth part is quite close to the 1st blade coating station and the machine speed is high.

Also, in machines where current coating cycle arrangements would allow time to close the paste supply, 15 where the fault occurs from the first fault detector 1.

The advantage of this valve arrangement of the treatment medium cycle is, inter alia, the advantage that the feed cut-off as well as the take-up is extremely fast, so that an uncoated product is produced in the vicinity of the fault site.

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In off-line machines, the invention avoids interference with roller seaming and reduces or even eliminates the need for intermediate rolls, resulting in significant cost savings.

The invention will now be explained in more detail with reference to the accompanying drawing, in which Figure 1 is a schematic diagram of an embodiment of one embodiment of the invention.

30 Modern paper machines have a large number of web and its quality measuring devices, from simple sensors to sophisticated camera and imaging equipment. Thus, the required information on web thighs or edge ribs may already be available from existing devices. In particular, machine vision systems are readily adapted for use with the present invention. If the expression is made in one place only, it is most advantageous to do so immediately after the dryer group before the first coat. This way, most faults can be detected because tears can still occur in the dryer group. Expression can also be made between dryer groups. If the expression is made solely after, for example, the press section, the reliability is reduced. Of course, it is most advantageous to use as many detectors, especially existing ones, when reasonably possible.

In addition, the technology of the present invention can also make it profitable to install a fault detection on an off-line-15 coating machine immediately after the unwinder. This would also significantly improve the tolerance of the holes and edges of the off-line machines and facilitate the passage of the seam.

When a hole or edge failure is detected or a seam-20 position is detected on an off-line machine, proceed as follows. First, it is calculated when the fault is at the coating and then the coating is cut off when the fault is at the coating and for the duration of the fault. The coating break is made in both short-stay coaters and conventional cutter tops by first interrupting the coating feed and then lightening the blade load. With short dwell coaters, the break can be made so that it takes about 1 s from the start of the break to restart the coating. If the break is longer, the blade must be cooled with a ve-30 jet or water spray to prevent it from overheating. Because of the high production speeds of modern paper machines, the web can travel about 20 to 30 meters in one second, depending on the production speed. Most track errors are significantly shorter than this, so simply controlling the overcoat on / off is enough to overcome the error. Due to the high speed, the coating control need not necessarily be synchronized at all with the detector if the detector is 5 close enough. In this case, simply triggering the on / off function of the overlay at a suitable distance may be sufficient. However, control systems for paper and board machines have computing power for complex synchronization. Correspondingly, the operation of the calendars is controlled by lightening the load and directing the load upon failure through the calender.

In this case, in addition to analyzing fault information with sufficient accuracy and speed, the web-opening functions of the top-loading stations must be fast enough to allow the machine to react to detected faults before the failure of the web reaches the machine part in question.

This requires that the response speed of the machine section be faster than 20 pi than tmax in the equation: tmax = s / v where s = web measurement from the first machine defect detector to 25 machine parts, mv = machine running speed, m / s There is no such need for have never been before. So the problem is 30 new ones. Apparently, in particular, the coating compositions are compressed to such an extent prior to the applicator that, due to their air content, the application of the treating agent cannot be practically immediately interrupted, even after closing the conventional inlet valve of the station. After closing the feed valve 9, the pressure on the coating decreases, thereby expanding its volume and pressing the coating onto the applicator. Other relevant factors include the slowness of the mass in the flow of the tubing 5 to be applied and the swelling of any rubber tubing, etc., under pressure.

According to the present invention, the fast acting curing feed cut-off valve 10 is located either directly adjacent to or immediately adjacent to the applicator beam so that a maximum of 1.5s from the signal given by the machine control takes physical delivery of curing agent to the web.

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The off-line machine doesn't have to be as fast.

In the coating cycles of blade coating stations, cutting off the coating feed to the station is currently based on the so-called. upper / lower rotation-20 to the valve assembly to isolate the coating cycle from the station during a break during washing of the coating station.

This valve system is ideally located reasonably close to the station, for example under the station's collecting tray, but with a wide machine, the distance from the vent-25 brick to the application bar itself is always more than five meters, and more typically about ten meters.

Previous solutions for positioning the valve assembly have come to such a location because, on the one hand, attempts have been made to minimize washable piping, but on the other hand, the valve work must have been able to be conveniently led back to the machine tank.

In designing such an upper / lower rotary valve, some attention has been paid to the speed and reproducibility of the valve, mainly to facilitate position pickup. However, it is characterized in that the valve system has not only been used for rapid shutdown of the coating flow, but while the coating flow to the station has been switched off, the coating has been provided with an exit path back to the return circuit. This is due to the fact that in typical up / down roll valve operation, the coating feed is run down to the entire coating station for intermittent washes, about 10 to 30 minutes. If there was no escape route to the coating pressure exerted by the pumps, the pumps would fail within this time.

Possible practical implementation of the coating cycle according to the invention

In order to stop the flow of the coating to the station only to open the station by the time of failure, the station requires a fast way to cut off the supply of the coating 20. In the most commonly used Jet and Short Dwell type drives in high speed coating machines, this requires the installation of a quick acting valve or valve assembly (if there are multiple feed points) between the coating nozzle and the rest of the machine cycle. Since these valves are only held for a maximum of a few seconds, it is not necessary to provide a return circulation to the coating but to increase the pressure at the pressure side of the valve. This has been tried and has not damaged the screw pumps typically used for coating feed.

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In the following, some embodiments of the invention will be considered with reference to the accompanying drawings, in which:

Figure 1 illustrates one valve arrangement 11 for interrupting the coating feed in accordance with the invention.

Figure 2 illustrates one embodiment of a coating line with driers and fault detectors.

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Figure 1 shows one example of an optimal arrangement for cleaving the coating. Except for the cut-off valves, the passage of the treatment medium, in this case the coating of the blade cover, corresponds to the current general arrangement described above. The figure shows only a part of the devices in the coating cycle. The coating arriving at the coating 9 is first treated with a strainer and a deaerator 1. From the extractor 1, the coating passes to a feed line 2 which forks before the coating 9 into two feed branches 3, 15 4. These branches 3, 4 lead to the feed branch 9. leads to the coating line returning to the tank. Shutoff valves 5, 6 are provided at the exit points of the return arms. These valves direct the coating back to the tank for washing or other maintenance of the coating 20.

In the solution according to the invention, in the example of the coating station, in the machine rotation of the blade coating station 9, high-speed cut-off valves 10 are added directly to the nozzle bar feed without recirculation. The valves are most preferably mounted directly on the nozzle bar, separated only by the required fittings. However, the valves may, if necessary, be located slightly apart from the nozzle bar or the corresponding casing casing distributing member, but in this case the connection must be made by non-flexible tubes or hoses. These include metal tubes and sufficiently reinforced hose reinforcements. For example, steel braided reinforced hoses can be used because their volume does not substantially change from internal pressure.

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The greatest distance between the shut-off valve and the coating manifold can be regarded as the distance between the manifold and the valves forming the casing thread. The shut-off valves 5 should thus be located between the manifold and the circulating valves. There is no other way to speed up the closing time. However, the closer the cut-off valves are to the circulation valves, the longer the required treatment agent feed delay. As already indicated above, the coating feed must be capable of being cut off within a maximum of 1.5 seconds to the end of the cut-off signal to the paper in order to respond to the disturbance. For the length of the piping, this means that the cut-off valves may not be located more than 5 m from the 15 pipeline from the nozzle beam or other treatment medium dispenser.

Figure 2 illustrates a typical typical operating environment of the present invention. Figure 2 illustrates a coating line comprising a pre-coating 22 and two surface coaters 24. The line comprises four cylinder 20 and five air dryers 21 and a calender 23. Additionally, the coating line is equipped with fault detectors 25.

In the example of Figure 2, the web comes from the last dryer cylinder group 20 of the papermaking machine to the pre-coating 22. followed by a normal double-sided coating line with coaters 24 and a non-contact dryer 21 with a dry cylinder group 20. At the end of the production line, a multi-nip cannula 23 has a web to form a final smoothness and a calender is followed by a roller.

After the last dryer cylinder group 20 of the paper machine, 5 are positioned on the edge cutter 26. Now, the first defect detector 25 is positioned on the last dryer cylinder group of the paper machine before the edge cutter, edge defects can be removed with a cutter according to the fault detector information. If necessary, the fault detectors can be positioned upstream of the paper-10 machine production line to give the edge cutter 26 more time to react and make the necessary cut. The following defect detector is located before the precoat 22 and ensures that the faulty web does not reach the precoat without action. Further in line are via-15 detectors 25 before each topcoat 24 and before calender 23.

In principle, for the operation of the invention, it is sufficient for the system to have one defect detector before the actuator 20, which must respond to a defect in the web. Preferably, at least one of the fault detectors is at the beginning of the production line so as to allow sufficient time for the fault to be reacted. One advantageous location is with the dryer cylinder group of a paper machine or board-machine, since upon arrival there is already a final web shape of the web and the risk of defects thereafter is no longer high. Likewise, information from the dryer cylinder group is well reacted. The number of MIs can be increased to any size, the correct number being limited by the ratio of the resulting reliability to productivity gains and the current financial input. For example, with blade coaters, the web is subjected to greater stresses and more defect detectors may be required, whereas in film transfer coating, it may not be necessary to monitor the web as much. In the case of multi-nip calendars, it must be ensured that a defective web cannot damage sensitive rolls, so that more fault detectors can be used and that justifying the placement of at least one detector just before the calender is justified. In the off-line 5 line, the first inexpensive and potential bug detection slot is after the unroller.

In summary, the following features illustrate various embodiments of the invention: A system for paper coating and / or calendering on a si-10 paper machine is provided for minimizing breaks, wherein the coating station is opened to a detected defect and the coating station coating is shorter than 1.5 seconds. from the cut-off signal to the actual end of the feed to the coating paper. The required fast feed cut-off is provided by valves located in the immediate vicinity of a nozzle bar or dispenser applying 15 coatings or other treatment agent. The valves are not provided with a discharge path that can be opened in connection with the valves when they are in use (so-called lower circulation). Thus, any return circulation between the feed pump and the sul-20 valve is kept closed. The distance from the cut-off valves to the nozzle beam along the piping is kept less than 5 m, and flexible hoses are preferably not used between the cut-off valve and the nozzle beam. There may be one, two 25 or more cut-off valves, depending on the number of supply lines of the applicator.

The invention can be applied to a variety of stations where a treatment agent is applied to the surface of paper or board. Thus, the invention is not limited to any type of application station or on or off machine layout, but for the above reasons and because of the characteristics of the blade coating stations, the greatest advantages of our invention are achieved with them.

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It is therefore clear from the above examples that numerous solutions other than those described above can be implemented within the scope of the invention. Thus, the invention is not intended to be limited to the 5 examples above, but the full scope of the appended claims should be considered.

Claims (13)

A method of interrupting the feeding of a processing substance by means of an application device used in the treatment of paper or paperboard, wherein method of processing substance is measured in the application device for spreading on the paper or cardboard and the input of the processing substance coming into the application device ( 9) interrupting means 10 for the treatment substance, characterized in that the input is interrupted in such a way that the treatment substance flow to the path being treated ends no more than 1.5 seconds from an interrupt signal. 15 Method according to claim 1, characterized in that the input is interrupted after an error in the path being processed is detected within the time tmax = s / v, where: s = the path measured from a first field detector of a machine to at least one device in a group 20 v = machine operating speed tmax - 1/5 S. Method according to any of the preceding claims, characterized in that the circuit (7) of the treatment line's input line network is kept closed as the input to the path is interrupted for the time the fault is ignored. Method according to any of the preceding claims, characterized by the method being applied in an on-line line e. Method according to any of the preceding claims 1-3, characterized in that the method is applied in an off-line line. An apparatus for interrupting the feeding of a treating agent by means of an application device (9) used in the treatment of paper or cardboard, the device comprising the application device (9) having a distribution means for the treating substance and at least one feeding line (3). , 4) for feeding the treatment substance to the distributor, characterized by at least one stop valve (10) arranged at each feed line (3,4) arranged at the feed line (3, 4) in such a way that the treatment substance flow to the path processed can be interrupted at most within 1.5 seconds from an interrupt signal. Device according to claim 6, characterized in that the shut-off valves (10) of the feed lines (3, 4) are attached to the distributor. Apparatus according to claim 6, wherein a circuit for a treatment substance is provided at least by means of valves (5, 6), characterized in that the interrupt valves (10) of the feed lines (3, 4) are arranged at the feed lines. (3, 4) between the valves (5, 6) and the application device. Device according to any of claims 6-8, characterized in that the shut-off valves (10) are connected to the distributor by inelastic lines. Device according to any of claims 6-9, characterized in that the distance between the shut-off valves (10) and the distributing means is at most 5 m. Device according to any of claims 6-10, characterized in that the device is arranged in an on-line line. Device according to any one of claims 6 - 10, characterized in that the device is arranged in an off-line line. Device according to claim 12, characterized by at least one error detector arranged shortly after the off-line line roll-off machine.