FI88185C - Procedure for re-entering a broken web through the coater - Google Patents

Description

1 38185

METHOD FOR DROPING A BROKEN WEB THROUGH THE COVER

(Separated from FI patent application No. 87 5311)

The present invention relates to a method for re-threading a web 5 into a coater using a headband through a coater, after the web is broken between the drawing roll and the winding of the coated web.

Numerous proposals have been made in the paper web coating technique to improve the quality of the coated product and the speed at which it can be made. Such coatings generally fall into one of two groups.

- The first group includes on-machine coaters and the second group includes of f-mach i ne coaters.

In on-machine coaters, the paper is formed, compressed, and dried, and the dried web is often tapered to obtain the surface properties of the web to be suitable for the next coating operation. The web from the calendar is fed into the coating! which may include coating rollers or which may include a short contact coating arrangement. In these 20 on-machine coaters, the web passes through the coating device at substantially the same speed as the web at which it appears.

In the past, when making paper webs, the webs came from the calender at a speed of about 10 m / s (2000 ft / min) or less, and feeding such a web at a speed of 10 m / s (2000 ft / min) through the next coating machine caused relatively few problems. Today, however, paper machines approach speeds of 20 m / s (4000 ft / min) or higher, and although many coaters are capable of handling webs at such high speeds, problems have now been encountered especially in attempting to coat relatively thin webs such as light coated webs and the like.

Often, when coating such light web grades at high speed, it has been found advantageous to coat these light webs in an off-machine coating machine.

In off-machine coaters, as the name implies, the web is wound from the sonication process onto a roll, and the rolled roll is then conveyed to an unwinding station, where the web is unwound from the roll and fed at an acceptable coating speed through a coating device. It is apparent that with the ever-increasing speeds at which webs are made in paper machines, off-machine coaters are being used more and more.

When coating with an off-machine coater, the coater does not have to operate at the same speed as the web-finished paper machine. However, in order to maintain an acceptable coating production rate, the coating must operate at coating speeds11a that are generally greater than the speed at which the paper machine produces the web. The coating delivery performed in the off-machine coater generally involves unwinding the paper from the unwinding stand and then tearing the first headband from the web, which headboard is reinforced. This first head-export strip is then threaded through the draw roll at a low threading speed. The first headband 30 is then fed at a low threading speed through the end 1 -1 thinning device. After the first headband is threaded through the coater using cooperating threading ropes or the like, the headband is widened incrementally between the unwinding stand and the draw roll until a full sheet web passes through the coater. Next, the unwinding stand, the traction roller and the coating device 5 are simultaneously accelerated from a low blowing speed to a high coating speed, which can be up to 20-25 m / s (4000-5000 ft / min). When the coating speed is reached, the coating of the web passing through the coating device begins. It is not uncommon for the practical operation of such an off-10 machine coater to result in eight (8) or more web breaks during a 24 hour production period. Whenever such an interruption occurs, an interruption is detected and an alarm signal is generated, resulting in the immediate stopping of the entire coating device, the unrolling rack, the traction roller 15 and the coating device.

Each time a break occurs, the web must be threaded through the threading device at a low threading speed, as mentioned above. In practice, the ratio of web breaks in the coating device to the number of breaks between the unwinding rack and the draw roll 20 is in the range of 20 to 1. Whenever the web breaks, the entire coating line must be stopped and re-threading can take 25-50 minutes from emergency stop to main stop. Because there are so many outages in the coating machine 25, in order to keep up with the amount of paper produced by the paper machine, the coater must operate well above the production speeds of the corresponding paper machine. speeds. Alternatively, it has been found necessary to suspend production of the paper machine for the time 30 when the off-machine coater is trying to catch the paper production of the paper machine. Such a shutdown or speed reduction of the paper machine is clearly not desirable or: commercially economical.

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The present invention addresses the problems associated with production losses of a coated product due to time-consuming delivery of the re-threading of the coating apparatus after a web break. The idea of the present invention is, in principle, to remove a full-width web between the drawing roll and the coating device after a break in the coating device, while the coating device is still maintained at a coating speed of 1a. The second headband is cut into a full-width web 10 between the unrolling rack and the draw roll, and this narrow second headband is threaded through the coating device at a coating speed. This re-threading of the coating device at the coating speed can in many cases be performed in less than a minute. It will be apparent to one skilled in the art that although during the aforementioned threading operation, except for the narrow head portion, the full width web is removed to the scrap paper shaft in about one minute, this loss of paper is much more economical than loss of production due to prior art coating. the web is re-threaded with a low thread rate delivery which, as noted above, takes 25-50 minutes.

The present invention seeks to avoid the above-mentioned problems and disadvantages associated with the known proposals for performing re-threading at a slow speed after a break, and the invention provides a coating method which constitutes a significant advance in the known coating technique.

It is an object of the present invention to provide a method of using a coater in which an unrolling rack, a draw roll and a coating device are maintained at a coating speed after the web breaks between the draw roll and the coated web receiving roll.

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The full-width web from the drawing roll stack is removed to the first flap. A second narrow headband portion is cut from the full-width web between the unwinding rack and the draw roll, and this second narrow headband portion is blown through the coating device at a coating speed while the rest of the full-width web is removed to the first jet. After the second narrow headband portion is threaded through the coating device, the second narrow headband portion is widened to the full width 10 of the web so that the full width of the web passes through the coating device, after which the web coating is restarted.

It is an object of the present invention to provide a method of using a coater which comprises widening a second headband passing through the coater to full width and subsequently coating the full web as it passes through the coater and then winding the coated web. le rullalle.

It is an object of the present invention to provide ai-. A method of using a coater 20, comprising using a first cutter to cut a second narrow headband portion between the unroller and the draw roll and widening the second narrow headband portion to the full width of the web after re-threading the coating device.

. Other objects and advantages of the present invention will become apparent to those skilled in the art upon review of the following detailed description taken in conjunction with the accompanying drawings and the content of the appended claims.

According to the invention, the above objects are achieved by a method comprising the steps of: holding an open roller, a drawing roll stack and a coating device at a heading speed, removing a full-width web from the drawing roll stack into a first jet, cutting a second narrow end The second narrow head tin strip portion moves at a coating speed, the second narrow head tension strip portion is threaded through the coating apparatus at a full speed, while the remainder of the full-width web is removed to the first web. the web passes through the coating apparatus, resuming coating of the web, and rolling the coated web.

The step of removing the full sheet web also includes returning the removed web for re-fiberization.

The step of cutting the second headband portion also includes using a first cutter interposed between the unwinding rack and the draw roll so that the first cutter cuts the second narrow headband portion from the removable full width web. The second narrow headband portion 20 has laterally spaced first and second edges for tapping the threading of the second narrow headband portion into the coating apparatus.

The step of threading the second headband portion also includes feeding a second headband portion between the co-operating threading ropes of the coating device such that a second headband portion formed between the drive roll stack and the first scrap shaft is fed to the coating speed. The second headband portion is blown through the coating device at a coating speed and the second headband is fed through the coating device, while the full-width web, except for the second headband, is removed to the first jet shaft.

The step of loosening the second headband portion also includes moving the first cutter in the cross-machine direction 5 so that as the full web moves relative to the first cutter, the second narrow headband portion widens incrementally until a full width web passes through the coating apparatus. The first edge of the second flared portion is machine direction and its third edge is oblique to the first edge 10 with the second flared portion being between the second narrow headband portion and the full width web.

In an alternative embodiment of the present invention, the widening step si -15 of the second headband portion also includes moving the first cutter in the transverse direction of the machine so that the second narrow headband portion stretches increasingly until the head! 1 the first part of the weaving device - a full-width web passes through it. The full-width web from the first portion is removed to the second wreck shaft, and a third headband is cut from the 20 full-width webs between the first portion and the second wreck shaft. The third headband is fed at a head speed in the direction of travel of the coating apparatus through the subsequent second part.

Although the present invention is particularly useful for off-machine coating for paper web coating. in increasing the production speed of the lyst, my profession in the field Ehei -. It is obvious that the method of the present invention should not be limited to an off-machine coater for coating paper webs. Instead, many modifications and variations of the basic principle described herein can be considered in the present invention. These changes and modifications do not depart from the spirit and scope of the invention as defined in the appended claims.

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Figure 1 is a side view of a typical known off-machine coater in which, after the web is broken in the coater, the entire coater is stopped and the coater is re-threaded at a slow threading speed.

Fig. 2 is a side view of an off-machine coater of the present invention showing a first cutter between the au rolling pin and the draw roll and a wreck shaft located below the draw roll.

Fig. 3 is a plan view of the apparatus shown in Fig. 2 showing the first step of the operation sequence after web breakage between the draw roll and the receiving roll;

Fig. 4 is a view similar to that shown in Fig. 3 except that it shows a second step in which a second narrow headband portion is cut from a full-width web between an open-winding stand and a draw roll. Figure 4 also shows the threading of the second narrow headband section at the coating speed into and through the coating apparatus, while the rest of the full sheet web is removed to the first flap.

Fig. 5 is a view similar to that shown in Fig. 4 except that it shows the widening of the second narrow headband portion to full width so that the full width web can pass through the coating device at a coating speed.

Fig. 6 is a view similar to that shown in Fig. 5 except that the full 1-sheet web begins to pass through the coating apparatus.

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Figure 7 shows the resumption of coating of the re-threaded web passing through the coating apparatus.

Fig. 8 is a side view of a second embodiment of the present invention in which a coating apparatus includes first and second portions with a second waste shaft disposed between the first and second portions to allow removal of the full web from the first portion into the second shaft while the second cutter cuts a third headband through the second part of the coating apparatus-10.

The same reference numerals refer to similar parts in different embodiments of the present invention.

Fig. 1 is a side view of a typical known off-machine coater 10 having an unwindable roller 12 rotatably supported by an unwinding stand 14. A plurality of guide rollers .. and 15,16,17,18,19,20 and 21 guide a full sheet web W so that the web W is guided towards the first nip formed between the first and second rolls 24 and 26 of the traction roll stack indicated generally by reference numeral 28. The web 20 is manually torn from the first narrow headband portion 32 between the unwinding stand 14 and the draw roll 28, as is well known in the art described below. This allows the first narrow headband portion 32 to be threaded through the draw roll 28. When the narrow headband portion 25 is threaded through the traction roll 28 at a threading speed 1a, ·; ·. the first headband portion 32 coming from the pull-up lever 28. is fed at a low spray rate of 1a over the controls 33.34, 35.36, 37.38 and 39. This first headband 32: is fed between cooperating threading ropes extending around the coating device generally indicated by reference numeral 44, as is well known in the art. Cover-i. As the applicator 44 rotates at a slow threading speed, the first narrow headband portion 32 is guided through the coating fence 44, and when this is done, the first narrow headband portion 32 is widened to the full width of the web W.

When the first headband portion 32 is widened to the full width of the web 5W, the full width of the web VI enters and passes through the coating device 44 and the unwinding stand 14, the pull roller 28 and the coating device 44 are then accelerated to the coating speed, after which the web can be coated.

The above-mentioned start-up delivery associated with such known off-machine wrappers may take a period of 25 to 50 minutes. In addition, in the event that the web W breaks somewhere between the draw roll 28 and the winding roll 46, the following rewinding sequence has been used in the past. First, a web break is detected and the alarm signal is generated so that the open-winding stand 14, the traction roller 28, and the coating device 44 decelerate rapidly to a stop state. The broken web remaining in the coating apparatus 44 is removed using high power water jets or the like. Next, a new headband portion 32 is cut from the web VI so that this headband portion comes from the drawing roll stack 28 at a low threading speed 1a.

This new first narrow headband portion 32 is threaded into the coating apparatus 25 while the coating apparatus 44 is rotated at a low threading speed. As the threading ropes thread through the entire length of the coating device 44 of the narrow first headband section 32 at a low threading speed, the first headband 32 is widened to a full width 30 so that the full width web VI is threaded through the coating device 44 at a speed. It can similarly take an average of 25-50 minutes to complete this re-threading operation. It is not uncommon for off-machine

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in the operation of the coaters, there are at least 8 web breaks during an arbitrary 24 hour coating production operation. The loss of production following the time required to start such an off-machine coater, combined with other major production losses following several web breaks, has resulted in the coating activity that has proven undesirable in the known proposals.

According to the present invention, there is provided a method of using a coating that increases production rates when a rupture occurs between a draw roll and a roll.

Figure 2 shows a paver 10a of the present invention with an unrolling rack 14a, a pull roll 28a, a first wreck shaft 29, a first cutter 40, and a coating apparatus generally designated 44a.

Usually, when a break occurs during the coating delivery, this break of the web Wa occurs as the web Wa passes through the coating device 44a. Although web breaks occur occasionally between the unwinding stand 14a and the take-up roll 28a V, the ratio of the breaks between the take-up roll 28a and the receiving roll or take-up roll 46a to the number of breaks V between the take-up roll 14a and the take-up roll 28a is 20. 1. In the event of a web break, the next sequence of steps, shown in Figures 3-7, is performed! to re-thread the device 44a and return to the coating-25 mode of operation.

: Figures 3-7 are the coating apparatus shown in Figure 2. 44a are views showing a new threading operation. . order of measurement.

Figure 3 shows how, in the event of a web break between the stack roll 28a and the receiving roll 46a, the unwinding stand 14a, the draw roll 28a and the coating device 44a are maintained at a coating speed Vc of 12,881,85. Figure 3 also shows the downward orientation of the full-width web from the traction roll stack to the first wreck shaft 29 and the first cutter 40 starting to cut the second headband 42.

Fig. 4 shows the first cutter 40 continuing to cut the second narrow headband portion 42 from the full width web and orienting the second headband 42 through the coating device 44a rotating at the coating speed Vc.

Fig. 5 shows the first cutter 40 moving laterally with respect to the second narrow headband 42 so that the second headband 42 widens into a full-width web Wa such that the full-width web extends through the coating device 44a running at a coating speed Vc.

Figure 6 shows the end of the full-width web Wa starting to extend through the finishing device 44a.

Figure 7 shows the re-coating of the full-width web, as indicated by cross-shading, and the winding of the coated web on the receiving roll 46a.

In both of the above operations, both to restart the coating delivery and to re-thread the web after the web breaks, a second headband 42 is threaded through the coating device 44a at a coating speed Vc, thus avoiding the time consuming practice of threading the headband. is then accelerated at a coating rate of 1 e Vc.

The step of removing the full-width web Wa, as shown in Figures 3-5, also includes returning the removed web 30 for re-fiberization.

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The second headband cutting step as shown in Figures 3-5 also includes the use of a first cutter 40 interposed between the unwinding stand and the drive roll stack 28a such that the first cutter 40 cuts the second narrow headband portion 42 of the removable full width web Wa. The second narrow headband portion 42 shown in Figure 5 has laterally spaced parallel first and second edges 56 and 58 to facilitate threading of the second narrow headband portion 42 into the coating device 44a.

The step of threading the second headband 42 as shown in Figs. and threaded at a coating speed Vc through the coating apparatus 44a. The second headband 42 is fed to the cover. 20 while the full 1-web web from which the second headband 42 is separated is removed to the first waste shaft 29.

Lev · 'The widening step of the second headband 42 shown in Figures 4 and 5 also includes moving the first 1 or 25 chutes 40 in the transverse direction of the machine so that as the full web moves relative to the first cutter 40, the second narrow head portion 42 widens until the coating 44 extends. extends through a full-width web. As shown in Fig. 5, the first edge 56 of the second widening portion 60 is machine direction and the third edge 62 is disposed obliquely to the first edge. : 56 with the second widening portion 60 located between the second narrow: head strip portion 42 and the full strip portion evolved between its web Wa.

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In an alternative embodiment of the present invention as shown in Figure 8, the step of widening the second headband also includes moving the first cutter 40b in the transverse direction of the machine so that the second narrow headband portion 42b widens incrementally until a full width web extends through the first portion 64 of the coating device 44b. The full-width web Wb from the first portion 64 is removed to the second waste shaft 66. The second cutter 67 cuts the third headband from the full-width web 10 between the first portion 64 and the second waste shaft 66 in the same manner as the second headband 42b is cut. This third headband is fed at a coating speed 1a through the second part 68 below in the direction of movement of the coating device 44b.

The coater for carrying out the method of use shown in Figures 2-7 includes an unwinding stand for unwinding the web to be coated and a drawing roll placed downstream of the unwinding stand in the direction of movement. A first wreck shaft is positioned below the draw roll so that when the first headband is threaded through the draw roll and the first headband is widened to form a full width web extending through the draw roll, the full web from the draw roll stack is removed. The coating device for coating the web is accelerated together with the unrolling rack, the draw roll and the full-width web at a coating speed such that the web to be removed to the first wreck shaft reaches the same coating speed as the coating device. A first cutter 30 is interposed between the unwinding stand and the draw roll to cut the second headband from the full width web from the drawbar so that the second end strip is fed through the coating device at a coating speed. The first cutter moves relative to the web

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in the direction of movement before the coating device so that the second headband is widened to allow the full-width web to pass through the coating device at a coating speed. This arrangement avoids the need to thread the web at a threading speed through the coating device after the web is broken. By using this device as mentioned above, the production losses necessarily associated with such threading at the speed of threading are avoided.

Using the arrangement presented herein, the paper machine can operate completely independently of the coater, and the coater can operate at substantially the same speed as the paper machine and pull or discard bad paper past the coater.

For example, in the case of a coater operating at a speed of 20 m / s (4000 ft / min), a continuous on-machine coater 15 may have eight breaks per day and may produce 738 tons per day per roll.

In contrast, the corresponding off-machine coating arrangement under the known proposals would produce only 624 tonnes per day. Based on this, it is apparent that the on-machine-20 coater is 18% more productive than the corresponding off-machine coater. In practice, this would mean that in an on-machine coater the web would be coated at 19.73 m / s (3891 ft / min), while in the case of an off-machine coater the average paper production would have to be slowed to 17.88 m / s ( 3527 ft / min).

From the foregoing, it will be apparent to those skilled in the art that the downtime required for threading and re-threading a second headband at low threading speeds 11a can be greatly reduced by applying the idea of the present invention.

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Not only does the arrangement of the present invention save downtime when starting a coating delivery, it particularly achieves large savings in dealing with situations where multiple web breaks occur.

Claims (6)

A method of re-entering a web by means of a feeding tip through a coating device (44a) after the web (Wa) has ruptured between the draw roll stack (24a) and the roll (46a) of the coated web, characterized in that the resetting operation comprises the steps of: maintaining the roll-off box (14a), the draw roll stack (24a) and the coating device (44a) at the coating rate (Vc), removing the entire web (Wa) coming from the draw roll stack (24a) into a first waste shaft (29), (40) of a narrow feed tip portion (42) from the curved web (Wa) between the roll off shank (14a) and the draw roller stack (24a), the narrow feed tip portion (42) moving at the coating speed (Vc), entering the narrow feed tip portion (42). through the coating device (44a) with the coating speed (Vc) while removing the remaining portion of the healing web (Wa) into the first waste shaft (29), and widening the narrow feed tip portion (42) to full web width so that the curved web (Wa) runs through the coating device (44a). A method according to claim 1, characterized in that the step of removing the cured web further comprises: returning the removed web for re-fibrillation. 3. A method according to claim 1, characterized in that the step of cutting the feeding tip part (42) further comprises: using a cutting device (40) positioned between the roll-off shank (14a) and the draw roll tape (28a) so that the cutting device (40) cutting a narrow feed tip portion (42) from the cured web being removed, said narrow feed tip portion (42) having laterally spaced parallel first and second edges (56, 58) to facilitate threading of the narrow feed tip portion (42) into the coating device (44a). Method according to Claim 1, characterized in that the step of threading the feed tip part (42) further comprises: feeding the feed tip (42) between cooperating thread lines in the coating device (44a) so that the feed tip part (42) formed between the draw roll tape (28a) and the first waste shaft (29) with the coating rate (Vc) is measured between the lines and entered with the coating rate (Vc) through the coating device (44a), the feed tip portion (42) being measured through the coating device (44a) while removing the healing web except the feed tip portion into the first waste shaft (29). 5. A method according to claim 3, characterized in that the step of widening the feeding tip part further comprises: moving the cutting member (40) in the transverse direction so that as the healing web (Wa) moves in relation to the cutting means (40) the narrow feeding tip part ( 42) becomes progressively wider until a healthy web (Wa) runs through the coating device (44a), the first edge (56) of the wider portion (60) being in the machine direction and a third edge ... (62) ) are diagonally in relation to the first edge (56) and the portion which is wider is between the narrow feed tip (42) and the curved web (Wa). 22 88 1 85 6. A method according to claim 5, characterized in that the step of widening the feeding tip part further comprises: moving the cutting member (40) in the transverse direction or the narrow feeding tip part (42) becomes progressively wider until a whole web (Wb) runs through a first part. (64) of the coating device (44b), removing the healing web (Wb) coming from the first portion (64) into a second waste shaft (66), cutting a further feed tip from the healing web between the first portion (64) ) and the second waste shaft (66), feeding the additional feed tip with the coating speed through a second downstream portion of the coating device.