CN203904771U - Arrangement for treading of tail part of web material in fiber web material machine - Google Patents

Abstract

The utility model relates to an arrangement of treading of a tail part of web material in a fiber web material machine. The arrangement comprises a forming device (18) used for forming the tail part (10) of the web material from fiber web material, a cutting device (13) used for cutting the tail part of the web material (10), a treading apparatus (16) for the tail part of the web material behind a maintain point (14), used for releasing the tail part (10) of the web material from the surface of a machine part (12) and forwardly conveying the cut tail part (10) of the web material, wherein the cutting device (13) is arranged before a maintain point (14') in front of the treading apparatus (16) for the tail part of the web material; and the cutting device (13) is arranged in a way that cutting of the tail part (10) of the web material happens on an unsupported part between two maintain points (14) on the tail part (10) of the web material.

Description

Arrangements for threading web tails in fiber web machines

technical field

The invention relates to an arrangement for threading a tail in a fiber web machine comprising rotating machine parts for forming a holding point forming at least one contact with the tail, said arrangement include:

A forming device for forming a web tail from a fibrous web;

cutting device for cutting the tail of the web;

tail threading equipment, arranged after the holding point, for releasing the tail from the surface of the machine part and conveying the pre-cut tail forward;

In this case, the cutting device is arranged before a holding point located in front of the tail threading device. The invention also relates to a corresponding method. the

Background technique

US Patent No. 5413017 discloses a cutting device based on rotating blades arranged in cooperation with a vacuum belt conveyor. In this proposed arrangement, the web tail to be drawn down is released from the surface of the drying cylinder functioning as a machine part by means of a doctor blade which thus forms the release means. After being released, the web tail is directed towards the rotating blade by means of the rotating blow plate and the web tail is thereby severed. Thus, the rotating blow plate forms the delivery tool. The pre-cut web tail end is conveyed forward on a vacuum belt conveyor. This at the same time avoids that the web tail has already been directed to the broke-handled part back to the vacuum belt conveyor. This means that even thicker web tails can be cut and forwarded without wrinkling. the

The above-mentioned rotary blowing plate runs slowly and requires a large installation space. Furthermore, the transport of the cut tail between the cutting device and the vacuum belt conveyor is unreliable. The fact that the tail enters the cutting device slack also adds to this unreliability. And the blade itself also constitutes a safety risk especially during maintenance operations of the fiber web machine. It is therefore necessary to use a guard structure, which complicates the design of the cutting device and may cause jamming due to the accumulation of a large number of web tails between the guard structure and the blade. the

A common concept in prior art solutions is that the cutting and releasing of the tail take place at the same location and are often connected to each other with the same tool. For example, a holding point refers to a point of contact between a roll and a roll of fabric or a nip between two rolls, which advances the fibrous web when the rolls are actuated. Then, after cutting, especially for fibrous webs with a larger basis weight, slack can be generated in the tail because the tail will turn sharply due to the cutting operation and the cutting operation will slow down the travel of the tail. On the other hand, a slack tail is more difficult to guide forward during tail threading and may create unnecessary pockets or double ends in the tail. This tends to cause the tail to break or cause the tail to fall out of the tail threading device. the

Contents of the invention

It is an object of the present invention to provide an arrangement and a method for threading a tail in a fiber web machine which enable the tail to be conveyed stretched forward after cutting the tail. More precisely, the arrangement according to the invention is characterized in that the cutting device is arranged such that the cutting of the tail takes place on the unsupported part of the tail lying between the two holding points. More precisely, the method according to the invention is characterized in that, in the unsupported part of the tail between two holding points, the tail is cut before the holding point before the tail threading device. This enables the tail thread, which arrives from the holding point before the tail threading device, to be guided further directly by the tail threading device without cutting, thereby completely or at least largely avoiding the Creates a slack tail. Surprisingly, it is possible to cut the tail in an open draw before the holding point, since then the tail is temporarily free of draw. However, with the method according to the invention, the web tail can be conveyed stretched to the holding point and further after the holding point. the

In particular, the invention provides an arrangement for threading a web tail in a fiber web machine comprising rotating machine parts adapted to form at least one contact point with said web tail The holding point, said arrangement comprises: forming device, is used for forming tail from fiber web; Cutting device, is used for cutting said tail; Tail threading device, it is arranged after holding point, with for releasing said tail from the surface of a machine part and conveying said tail being cut forward; wherein said cutting device is arranged before a holding point in front of said tail threading device, characterized in In that, the cutting device is arranged such that the cutting of the tail takes place in the unsupported part of the tail between two holding points. the

Preferably, the cutting device is located between the nearest holding point and the second closest holding point before the tail threading device. the

Preferably, the arrangement is suitable for use in the dryer section of a fiber web machine. the

Preferably, said cutting means and shaping means are arranged in the same space between two holding points. the

Preferably, the water cutter is configured to be movable laterally for cutting said web tail into a wedge shape. the

Preferably, the water cutter has a cutting sequence for cutting the tail into a blunt wedge shape. the

Preferably, said arrangement comprises: a doctor blade located behind the nearest holding point before said tail threading device; and a pull-down device located in association with said doctor blade to remove The fibrous web and the web tail cut from the fibrous web are guided from the doctor blade to a pulper included in the fibrous web machine. the

Preferably, said tail threading device comprised in the arrangement is adapted to transfer said tail to a calender. the

Preferably, the cutting device is located in the part of the tail that runs directly towards a holding point located behind in the direction of travel. the

Preferably, the tail threading device is substantially at the same level as machine components located in front of the tail threading device. the

According to the above arrangement of the invention, it is possible to achieve a web tail that almost corresponds to the course that the fiber web travels during normal operating conditions. the

Description of drawings

The present invention will be described in detail below with reference to some embodiments of the present invention shown in the accompanying drawings, wherein:

Fig. 1 is a basic side view of an embodiment arranged according to the present invention;

Fig. 2 is the basic side view of the second embodiment arranged according to the present invention;

Fig. 3 is the basic side view of the third embodiment arranged according to the present invention;

Figures 4a-4b show the bevel cut shape of a tail that has been cut with the arrangement and method according to the invention. the

Detailed ways

Figure 1 shows an embodiment of such an arrangement according to the invention for threading a web tail in a fiber web machine. In FIG. 1 the end of the drying section 50 and the calender 52 behind it are depicted. In the figures, the direction of travel of the fiber web is from right to left. The arrangement according to the invention can be used in particular in the dryer section of a fiber web machine, but also in the press section, or in applications generally requiring the use of a web tail and including open draws for the fiber web. The purpose of the tail threading of the fibrous web is to transport the tail 10 of the fibrous web and finally the entire fibrous web supported by the machine part 12 to a winder (not shown). Depending on the application, besides the support, the machine part 12 can also dry the fiber web (for example in the dryer section 50 ) or press the fiber web (for example in the calender 52 ). In this context, machine elements preferably refer to rotating rolls or dryer cylinders. In this context, fiber web preferably refers to paper or board. the

Tail threading usually takes place at specific stages. In other words, the web tail is not threaded through the entire machine in one go. Typically, the tail and the entire fibrous web run temporarily towards the pulper 44 at the end of various stages, such as the end of the dryer section 50 shown in FIG. 1 . This avoids the need to repeat the tail threading operation over the entire length of the fiber web machine if the tail should be broken before the winder. the

As shown in FIG. 1 , in the drying section 50 , a fabric loop 28 supported by guiding machine parts 12 ′ is arranged between the machine parts 12 . In this case, the fabric loop refers to the wire fabric arranged in a loop, while the guiding machine part 12' is the guiding roll. The holding point 14 is formed between the wire fabric of the fabric loop 28 and the dryer cylinder functioning as the machine part 12 when they come into contact with each other. By holding point is meant at least one contact point between a machine part and a fabric loop, or alternatively between two machine parts, which bears the fiber web during rotation of one or more machine parts and web tail. That is to say, when the fibrous web or web tail is at the contact point between the machine part and the fabric loop or between two machine parts, a holding is formed which bears the fibrous web and the web tail in the direction of rotation of the machine part point. the

The arrangement according to the invention comprises three basic parts. The first part consists of a forming device 18 for forming a web tail 10 from a fibrous web. The second part is the cutting device 13 for cutting the tail 10, while the third part is the tail threading device 16 for releasing the tail 10 from the surface of the rotating machine part 12 and making the thus cut The tail 10 is conveyed forward. The forming device 18 may consist, for example, of a knife cutter or similar device for separating the tail from the entire width of the fibrous web in the direction of travel of the fibrous web. The width of the tail may eg be 200 mm. In the embodiments shown in Figures 1-3, the fiber web is a board web, in which case it is preferred that the forming means consist of a knife-shaped cutter, since the board requires higher mechanical strength during cutting . The forming device 18 is located in front of the holding point 14' before the pulper 44; that is, in front of the machine part 12 in front of the pulper 44 in the direction of travel of the fiber web. More precisely, the forming device is preferably between the closest holding point 14' and the second closest holding point 14" in front of the tail threading device 16. In other words, the tail can also be in the downward run Formed in the region of the web. Preferably, as in the embodiment shown in the accompanying drawings, the tail is formed in the upwardly moving fiber web. 

The cutting device 13 is a device for cutting the web tail 10, which according to the invention is located in front of the holding point 14' before the pulper 44; The front of the machine part 12 before the pulper 44. More precisely, the cutting device 13 is located in a so-called open draw section, so that the cutting of the tail 10 takes place in an unsupported part 19 of the tail 10 located between two holding points 14 . Preferably the cutting takes place during the drawing of the tail traveling from the lower machine part 12 to the upper machine part 12, ie upwards. Preferably, the cutting device 13 is in the vicinity of the machine part 12 preceding the pulper 44, between the machine part 12 preceding the pulper 44 and the nearest machine part 12 preceding said machine part 12. Since the web tail is formed by the forming device 18 according to Figures 1 to 3, the cutting device 13 is always located behind the forming device 18 in the direction of travel of the fibrous web. Preferably both the forming device 18 and the cutting device 13 are located in the same unsupported open draw section 19 of the fibrous web between the two holding points 14 . In this context, the wording "unsupported" means that in this open draw section between the holding points, the fibrous web and its tail are not supported by eg rollers, fabrics or similar support elements. The travel of the web tail and the fibrous web is only guided by the pulling produced by the pulling point behind it in the direction of travel. After the tail is cut, the tail is temporarily guided only by its linear momentum. Tail cutting takes place in the tail transfer zone where the tail runs directly towards a holding point located behind it in the direction of travel. the

The tail threading device 16 may consist of a device provided in association with the machine part 12 for releasing the fibrous web from the surface of the machine part 12 and conveying it onwards to the subsequent holding point 14 . The tail threading device 16 may comprise: a separate release device 46, which may be, for example, the pick-up blowpipe 36 shown in Fig. 2 or Fig. 3; a doctor blade structure or similar prior art solutions, which may be The fibrous web is released from the surface of the rotating machine part 12 without slowing down the travel of the end of the tail 10, thereby preventing slack. The tail threading device 16 may also comprise a transfer device 26 for the tail 10 which may for example consist of a vacuum belt conveyor as shown in FIG. 2 , a blowing plate or a simple plate. The transfer device 26 serves to transfer the web tail 10 released from the machine part 12 further towards a subsequent holding point 14, which may be, for example, a nip between calender rolls or a winder. the

In order to carry out the method according to the invention, the tail 10 is formed from a fiber web by means of a forming device 18 . When it is necessary to continue threading the tail at a distance, using the cutting device 13 in front of the holding point 14 in front of the tail threading device 16, between the two holding points 14 at the unaffected end of the tail 10 The tail 10 is cut in the section 19 of the support. The tail 10 is released from the surface of the machine part 12 and conveyed onwards with a tail threading device 16 . In other words, when it is desired to continue threading the web tail from the pulper 44 onwards, the forming device 18 comprised by this arrangement is at the point where the fibrous web travels past the holding point 14 and doctor blade 40 and further to the pulper 44 A web tail is formed in the web. When the tail 10 extends to the pulper 44 , the cutting device 13 cuts the tail 10 and thus causes the tail 11 before the holding point to enter the pulper 44 . The tail 10 located after the cutting point travels unsupported by its linear momentum to the holding point 14 , which pulls the tail 10 further to the tail threading device 16 . the

In such an application, it is preferred that the scraper 40 guides the web and tails destined for shredding to the pulper in combination with a drawdown tool (not shown). Preferably, the pull-down means consists of a pull-down blow. This pull-down function can create a gap at the cutting location when the tail leaves the holding point 14'. the

The cutting device used in the arrangement according to the invention is preferably a water cutter for cutting the web tail. A water cutter can cut the tail by moving the water jet laterally across the tail. Then, when the tail 10 is moved forward, a wedge-shaped chamfer 56 will be formed in the tail 10 as shown in Fig. 4a. This cutting operation can here be timed such that when the tail is finally cut off, the end of the chamfer just reaches the holding point, so that a nearly continuous draw in the tail can be maintained. Water cutting or blade cutting can be used in the method according to the invention. the

According to one embodiment, the cutting device has a cutting sequence which controls the water jets so that the water jets move quickly in the cross direction during the initial cutting phase starting from the first edge of the web tail, and when approaching the second edge Move more slowly. Thus, a blunt wedge 58 will be formed by the chamfer 56 of the tail 10, as shown in Figure 4b. After passing the blunt tip 58 , the jet of water will move more slowly, thereby forming the long edge portion 60 . The blunt shape provides greater resistance at the holding point to forces directed towards the tail of the web. the

An advantage of the arrangement and method according to the invention is that the web tail is prevented from being slack during forward transport. In prior art solutions, the tail cutting takes place after the holding point, to be precise only after the tail has been cleared from the surface of the machine part by means of the tail threading device. For reasons of space requirements, the tail threading device is therefore usually located below the shaft of the machine part so that the tail can be conveyed forward in a sharp turn or even in a loop before it continues to travel towards the subsequent holding point after it has been cut . Slack can then easily be induced, which will disturb the tail threading process. In the arrangement according to the invention, the cutting is already done before the holding point, in which case the web tail leaving the holding point can be released from the surface of the machine part as soon as possible after the holding point and be guided directly and Tensioning to the tail threading device and towards the subsequent holding point. The tail threading device may be substantially at the same level as the machine components located in front of the tail threading device. The expression "substantially at the same level" means that the tail threading device is located in the vertical space between the uppermost surface and the lowermost surface of the machine part. It is thus possible to provide an almost standard course of travel for the web tail according to the course of travel of the fibrous web during operation. the

Figure 2 shows another embodiment of the arrangement according to the invention. The figures clearly describe how the tail 10 can be released from the surface of the machine part 12 immediately after the holding point 14, so that it can be almost directly and via the transfer device 26 included in the tail threading device 16 (at This is a vacuum belt conveyor) guides the web tail 10 forwards towards a subsequent holding point not shown here. In this embodiment, the release device 46 of the tail threading device 16 comprises a pivotable pick-up blowpipe and the blow plate 24; the pick-up blowpipe 36 releases the tail 10 from the surface of the rotating machine part 12 by means of blowing air, And the tail 10 is conveyed forward by the blowing plate 24 . It is also possible to use a conveyor instead of a blown plate. the

FIG. 3 shows a third embodiment of the arrangement according to the invention, where the tail 10 is released from the machine part using a pick-up blowpipe 36 incorporated in the tail threading device 16 . In this embodiment, the location of the pick-up torch 36 is lower than in the embodiment shown in FIG. 2 . However, the release of the tail 10 takes place at a higher position than in prior art solutions, which allows a more direct advancement of the tail 10 to the subsequent holding point 14 than in prior art solutions. In this embodiment, the subsequent holding point 14 consists of a carrying sheave 38 which transports the web tail 10 onwards from this holding point. The carrier rope system may comprise a tail threading rope 37 and a sheave 39 which can be moved close to the machine part 12 for the duration of the tail threading process and out of the way during normal operation. the

Figures 1-3 show the application of this arrangement in connection with a dryer section applied in a double fabric run system. In this case, the machine part 12 is a roller, and a holding point 14 is formed between the roller and the fabric loop. The fibrous web moves unsupported into the open draw section between the holding points 14 . There are two fabric loops here: one at the top and one at the bottom. If the drying section is implemented as a single-fabric running system, a space can be provided on the cutting device between the machine parts by, for example, a loop formed by the wire section fabric, in which loop the fabric travels, for example via two rollers (not shown) . Such a design can be similar to the technical solutions usually used for fabric loops according to the prior art. A space is thereby provided for the cutting device between the fabric and the fiber web. The arrangement according to the invention is suitable for use in a dryer section in a single-fabric run or in a double-fabric run. the

Compared with the prior art and common practice, it is surprising that the tail of the web can be cut before the holding points, in the space between the holding points (where the web is not supported), in which case Here, the tail can remain draw-free for a portion of the distance. Since the tail is also moving at a significant speed during tail threading, there is a certain linear momentum which can keep the tail forward after cutting even without temporary pulling. Thus, the unsupported tail will continue to move in the same direction as before the cutting device. the

The basic components used in the arrangement according to the invention, ie the forming device, the cutting device and the tail threading device, can be similar to prior art devices, whereby the arrangement can be made simple and cost-effective. the

Preferably, the arrangement and method are suitable for use in board production, because boards are poorly foldable due to their rigidity, so it is very easy to keep slack during tail cutting and tail release when using the prior art. In this context, a board refers to a fibrous web having a basis weight exceeding 125 g/m ² . This arrangement is also suitable for paper production. The arrangement according to the invention preferably employs the method according to the invention.

Claims (10)

1. An arrangement for threading a web tail in a fiber web machine comprising a rotating machine part (12) adapted to form at least one contact with said web tail (10) Point of holding point (14), said arrangement includes: forming means (18) for forming a web tail (10) from a fibrous web; A cutting device (13) for cutting said web tail (10); Tail threading device (16) arranged after the holding point (14) for releasing said tail (10) from the surface of a machine part (12) and forwarding said web being cut tail(10); Wherein, the cutting device (13) is arranged before the holding point (14') in front of the tail threading device (16), characterized in that the cutting device (13) is arranged such that the pair The cutting of the tail (10) takes place in the unsupported part of the tail (10) between two holding points (14). the 2. Arrangement according to claim 1, characterized in that the cutting device (13) is located at the nearest holding point (14') and the second nearest holding point before the tail threading device (16) between points (14″). 3. Arrangement according to claim 1 or 2, characterized in that it is adapted for use in the drying section (50) of a fiber web machine. the 4. Arrangement according to claim 1 or 2, characterized in that the cutting means (13) and the shaping means (18) are arranged in the same space between two holding points (14). the 5. Arrangement according to claim 4, characterized in that a water cutter (34) is arranged transversally movable for cutting the tail (10) into a wedge shape. the 6. Arrangement according to claim 5, characterized in that the water cutter (34) has a cutting sequence for cutting the tail (10) into a blunt wedge shape. the 7. Arrangement according to claim 1 or 2, characterized in that it comprises a doctor blade (40) behind the nearest holding point (14') before the tail threading device (16) and a pull-down device located in association with said doctor blade (40) to remove the fiber web produced in the fiber web machine and the web tail (10) cut from the fiber web from said doctor blade (40) leads to a pulper (44) comprised in the fiber web machine. the 8. Arrangement according to claim 1 or 2, characterized in that the tail threading device (16) comprised in the arrangement is adapted to transfer the tail (10) to a calender . the 9. Arrangement according to claim 1 or 2, characterized in that the cutting device (13) at the tail (10) runs directly towards a holding point (14') located behind in the direction of travel in the section. the 10. Arrangement according to claim 1 or 2, characterized in that the tail threading device (16) is substantially in the the same level. the