FI86900B - FOERFARANDE OCH ANORDNING VID SPETSDRAGNING AV EN PAPPERSBANA I MAONGCYLINDERTORKEN AV EN PAPPERSMASKIN. - Google Patents

Abstract

Method and device in a multi-cylinder dryer of a paper machine in the threading of the paper web, said threading taking place substantially without a system of threading ropes. The web is passed along a meandering path, in twin-wire draw, over drying cylinders (10A,10B) and, in single-wire draw, on a drying wire (11), over drying cylinders (10;10 min ) and leading suction cylinders (20,20 min ) or rolls (20,20 min ). The leader (S) is guided by means of air blowings (F1) extending across a substantial proportion or the whole of its width (L1), said air blowings (F1) being applied from the doctor beam (12) to the area (K) of the by of its doctor blade (14) at a certain small angle (B) in relation to the plane of the doctor blade (14). <IMAGE>

Description

86900

Method and apparatus in a paper machine multi-cylinder dryer for paper web head export Förfarande och anordning vid spetsdragning av 5 en pappersbana i mängcy1indertorken av en pappersmaskin

The invention relates to a method in a paper machine multi-cylinder dryer 10 for paper web head export, which takes place mainly without a head-export rope, in which method the web is guided with air blows applied from the scraper bar.

The invention further relates to a blowing device for carrying out the method according to the invention, which is integrated in connection with the scraper bars of drying cylinders 20, comprising a transverse nozzle tube or a similar nozzle arrangement as a nozzle arrangement or a plurality of parallel nozzles.

25 As is already known, the drying section of a paper machine uses a so-called single-wire export or two-wire export. In this case, rope guide devices are generally used for the head export of the web, by means of which the headband cut from the full-width web is passed over the drying cylinders, after which the headband is applied to the full-width web. The main drive rope is a rather expensive and complicated device and has malfunctions. For this reason, an attempt has been made to arrange the headrest without a headrest rope. In particular, said rope-free heading methods have been applied to single-wire exports. Here, in part, we refer to a journal article by Sam Palazzolo: "No-draw drying," Tappi Journal, September 1990, 35 p. 225-228.

As stated in the above-mentioned magazine article, the difficulty in headlifting when using a single-wire rope is that the headrest belt tends to follow the smooth surface of the 2,869,000 drying cylinders and not the drying wire as it runs from the drying cylinder to the next suction turning cylinder or roll.

In order to ensure that the headband follows the drying wire in particular, air nozzle arrangements have been used in accordance with the above-mentioned magazine article, one of which is placed before each reversing cylinder and through which nozzle air jets are blown to control the passage of the headband. This is to ensure that the headband remains on the drying wire. After the headband reaches the suction zone of the reversing cylinder, the belt rests on it to the next 10 drying cylinders.

The disadvantage of the blowing arrangement described above is that if the headband has passed in connection with the scraper blade acting against the drying cylinder, the headband cannot be obtained thereafter without manually operated auxiliary blows. In head export, however, there is a need to drop the headband from the lower surface of several or all of the drying cylinders with a scraper blade into the wreck handling system below. This has not been readily possible with previously known ropeless web heading arrangements.

20

On the other hand, it is already known to use air blowing devices arranged in connection with the scraper beams in the drying section, but these blowing devices are generally used for air conditioning the drying section and their nozzles blow the entire transverse width of the web. Blower devices operating in connection with a scraper have also been used in the head export, but they have had several drawbacks and as such are not suitable for use in a poor head export. With regard to said previously known devices, reference is made, by way of example, to FI patents and publication publications Nos. 50263, 54954, 62571 and FI patent applications Nos. 30, 833590 and 894609.

The main object of the present invention is to provide new solutions to the problems discussed above so as to largely avoid said drawbacks.

86900 3

In order to achieve the above and later objects, the method of the invention is mainly characterized in that said air blows are applied to the area of the tip of said scraper bar at a certain small angle B to the plane of the scraper blade, the angle B being set in the range B - 5 ° to 45 °, preferably in the range B - 10 ° ... 30 °, and that said blowing both removes the headband from the scraper steel and transfers it to the drying wire for further transport and ensures that the headband remains on the drying wire.

10

The device according to the invention, in turn, is mainly characterized in that the blowing direction of said nozzles is directed at a certain small angle to the blade plane of the scraper in the region of the tip acting against the surface of the drying cylinder, said nozzle tube and its nozzle openings extending transversely said nozzle tube is arranged so that its nozzles are located at a distance of about 100-300 mm, preferably about 200 mm, from the tip of the scraper blade.

The invention can be applied in drying cylinder groups with both single-wire and two-wire connections, if necessary along the entire length of the drying section. In connection with single wire export, the invention is suitable for use in both normal and inverted groups. Most preferably, according to the present knowledge, the invention is applicable to single-wire rods.

When, according to the invention, the blow pipes with their nozzles are placed precisely in connection with the scraper beams, an advantageous and sturdy "stand" is obtained for the blow devices without the need for separate support structures. Placing these structures in narrow cylinder gaps is difficult. As a result, the design of the head export auxiliaries is simplified and their maintenance and use are facilitated.

According to the invention, when the air jets are directed specifically at the tip area of the scraper blade 35 at a carefully selected angle in the area defined above with respect to the plane of the blade, the blows are turned 86900 along the pre-blade cylinder surface so that the blowing effect extends to the opening nip. Thus, a sufficient supporting effect of the blows on the headband is realized. Of course, the blows must use sufficient energy to provide a reliable transfer and support effect.

The invention will now be described in detail with reference to some preferred embodiments of the invention shown in the figures of the accompanying drawing, to the details of which the invention is not intended to be limited.

Figure 1 shows a single wire outlet drying section of a paper machine in which the method and apparatus of the invention are applied.

Figure 2 illustrates significant parameters in the placement and dimensioning of the method and apparatus according to the invention.

Figure 3 shows a side view of a first device implementation of the invention.

Fig. 4 shows the same device as Fig. 3 seen from the direction IV-IV.

Figure 5 shows the device according to the invention applied in an inverted single-wire outlet cylinder group.

Figure 6 shows an embodiment of the invention in a group spacing in which the transition from a single-wire export to a double-wire export and in a two-wire export group.

Figure 7 shows an embodiment of the invention in two-wire groups and between 30 groups thereof.

Fig. 1 schematically shows a group of cylinders with a single-wire outlet, in the upper row of which there are heated drying cylinders 10 and in the bottom row of rotating cylinders 20 with a torn and grooved outer jacket 20. Fig. 5 shows a corresponding inverted group, 86900 5 'top row.

According to Fig. 1, the single-wire export drying wire 11 passes serpen-5 sideways along the drying cylinders 10 and the turning cylinders 20 so that the web to be dried by the drying cylinders 10 comes into direct contact with the heated smooth surface of the cylinders 10 and the turning cylinders 20 includes a vacuum acting through its perforation in the sheath and 10 through a groove (not shown). For the runs of the wire 11 and the web with which they run together from the drying cylinders 10 to the turning cylinders 20, a blowing box 15 is arranged on the wire 11 side, e.g. a device marketed by the applicant under the trademark "UNO RUN BLOW BOX" and maintaining a suitable vacuum on the side of the wire 11 which ensures that the web remains on the surface of the wire 11 in said straight runs.

According to Figure 1, scrapers 20 acting against the free sub-sector of the cylinders 10, comprising a scraper bar 12, a scraper blade 14 connected to it by a holder 13, which scrapes and keeps the smooth surface of the cylinders 10 clean. The inverted cylinder group according to Figure 5 has corresponding screws above the cylinders 10 'against their free sectors.

25

According to the present invention, the scrapers 12, 13, 14 are provided with blowing devices for directing blows Fx against the tip portion 14 of the scraper blades, from which the blows bounce and "reflect" towards the nip opening in direction F2. The blows Fx and F2 prevent the situation where the headband S detaches from the drying wire 11 and follows the surface of the cylinder 10.

Fig. 1 shows the end of the headband S with reference SOI, which describes a situation in which the end Sc moves by the suction sector of the reversing cylinder 20 to the next cylinder 10. Figs. 2, 3 and 4 show a more detailed embodiment of the device. According to Figures 3 and 4, an air distribution pipe 22 is attached to the side of the scraper bar 86900 6, with a closed end 22a at one end and a blowing air supply connection 24 at the other end. The blowing pipe 22 has a number of nozzle holes 23 in width I ^. The blow pipe is secured in place by flanges 25 and 26.

5

Air jets Flf are blown from the nozzle holes 23 which are precisely directed to the point K (Fig. 3) in the vicinity of the tip of the scraper blade 14. Thus, in the invention, the blows Fj are not directed in the plane direction of the blade 14, but at a small angle B towards the blade.

10

Appropriate selection of the angle B causes the air jets Fx to be directed in the region of the tip of the pattern blade 14 so that the air jets bounce and "reflect" from the plane of the pattern blade and turn parallel to the outer surface of the cylinder 10 and apply to the nip N- in the direction F2. Thus, a sufficiently large transfer and support effect for the blows Fa on the headband is provided. Naturally, the energy Fx of the blows must be large enough to achieve the said purposes.

As is known, the scraper beams 12 are fastened at their ends by means of axle pins 16 in connection with their turning and loading devices (not shown).

In Fig. 4, the width S of the headband is denoted by L 2. Blows F! dimension L2 in the transverse direction is of the same order (width L2) of the head 25 in strip width s of the blowings Fx air is guided along the cylindrical surface 10 opens in the direction of the arrow F2, into the nip N-. Thus, by blowing F1, FZ, it is achieved that the headband T is pressed against the wire 11, in which position the suction effect of the blowing box 15 holds the strip S.

30

When the headband has to be dropped down on the wreck handling devices (not shown) at a particular cylinder 10, the blows F1 of the scraper under the cylinder 10 (whereby the headband S naturally passes to the scraper blade 14, which detaches it from the cylinder 10 and 35 and falls to the wreck conveyor below, which takes the wreck to the pulper. to operate on this cylinder 10, whereby due to the direction of the blows Fj they detach the scraper from the blade 14 and guide the wire 11 at the belt S to the support which takes the belt S over the suction zone of the reversing cylinder 20 to the next cylinder 10.

Figure 2 shows significant parameters in the dimensioning and orientation of the device according to the invention. The following are some typical preferred ranges of various parameters to which the invention is not limited. When the diameter of the upper cylinders is of the order of 1800 mm, the angle A is typically A - 35 ° ... 45 °. The perpendicular distance of the scraper blade 14 from the wire 11 at - S - 160-200 mm and the distance of the nozzle holes from the tip of the scraper blade L <200 mm and the angle C> 0 °. The orientation angle B of the jets Fj is generally in the range B to 5 ° to 45 °, preferably in the range 15 to 10 °. . .30 °. When the width of the headband is about 200 mm, the width of the blows in the transverse direction 1¾ is typically about 200-350 mm.

The energy of the blows Fx and F2 must be large enough to produce the intended effects. Therefore, the air pressure p 20 used in the blow pipe 22 must be dimensioned high enough. In general, this pressure p is in the range p - 50 ... 350 kPa. Em. the pressure range is preferably used in connection with the dimensioning of the nozzle holes 23 to be described later. However, the blowing width is not as critical in the invention as the blowing F! orientation angle B.

25

As the blow pipe 22, a perforated pipe can be used, the nozzle holes of which are typically 3-4 mm in diameter and 30-50 mm apart. The blowing width L2 may be narrower than the edge strip width L1, but it is generally not preferable for the blowing width 1¾ to be very much larger than the edge strip width L *. For example, blows Ft extending to a width of about 300 mm can lead an edge strip S of up to about 600 mm wide, but the widths cannot usually be reversed.

Figure 5 shows the use of blows in an inverted single-wire cylinder group with the drying cylinders 10 'in the bottom row and the reversing cylinders 20' in the top row. Blows Fx and F2 8

8 6 S'O O

the operation is as described above. Of course, from the top surface of the cylinder 10 ', the headband cannot be scraped for the wreck conveyor,

According to Fig. 5, in connection with the scraper beams 12, additional wooden halls F3 and F4 are arranged, on which the headband S is held by the turning cylinder 20 '. In addition, additional blow pipes 17 can be used between the turn cylinders 20 ', from which the blows F5 are directed towards the head conveyor belt S to guide it over the suction zone of the turn cylinders 20' to the next drying cylinder 10 '.

10

Figure 6 shows an embodiment of the invention in a group spacing formed between a single wire export group and a two wire export group. The web is transferred from the drying wire 11 of the single-wire export group by means of the suction box 32 after the guide roll 33a as a free pull Wp to the down wire 11B of the two-wire export group. The two-wire export group has two overlapping rows of steam-heated drying cylinders 10A and 10B in a known manner, as well as an upper wire 11A and a lower wire 11B, which are guided by guide rollers 31A; 31B. In connection with the drying wires 11A and 11B, blowing boxes 32 are placed near their guide rollers 31A; 31B to promote the support contact between the web and the wire.

According to Fig. 6, the scraper bars 12 are provided with a blow tube 22, from which blows according to the invention are applied to the area of the tip of the scraper blade 14. According to Fig. 6, in connection with the scraper bar 12 of the first lower drying-cylinder 25B, a second blowing F3 is also used, which is directed towards the passage path of the headband S. Blows Fx may not always be required in the double wire export area11a or blows Fi may be very weak. Instead, blowing F3 is even more helpful. In the two-wire export group, the web has free tensions W0 and the same 30 routes are also traversed by the headband S when passing it through the two-wire export group with the aid of the method and device according to the invention.

Figure 7 shows two consecutive two-wire export groups. the web is drawn as a free pull Wp from the group to the second and to the first lower cylinder 10B of the latter group 35 between the guide rollers 31A and 31B.

Screw beams 12 are arranged in both two-wire outlet groups, of which 86900 9 sa are at suitable points the blow pipes 22 according to the invention, from which the blows Fx and / or F3 according to the invention are applied in order to achieve the effects described above.

The following claims set out within the scope of the inventive idea defined by the invention, the various details of the invention may vary and differ only from those set out above by way of example only.

Claims (6)

A method in a paper machine multi-cylinder dryer for paper web head export, which takes place mainly without a head export rope, in which method the web guides a serpentine path with drying cylinders (ΙΟΑ, ΙΟΒ) and single wire outlet 20 ') or rollers (20,20') and in which the headband (S) is guided by air blows (Fx) extending over a considerable or full width (L 2) from the scraper bar (12), characterized therein. that said air blows (F!) are applied to the area (K) of the tip of the scraper blade (14) of said scraper bar (12) at a certain small angle B with respect to the plane of the scraper blade (14), which angle B is set in the range B - 5 ° ... 45 °, preferably in the range B - 10 °, .. 30 °, and 15 that by said blows (Fx) the headband (S) is both removed from the scraper steel (14) and transferred to k to the conveying wire (11) for further transport and to ensure that the headband (S) remains on the drying wire (11). A method according to claim 1, characterized in that in the method the blows (Fj) directed from the nozzles of the nozzle tube (22) connected to said scraper bar (12) to the tip area of the scraper blade (14) are turned into substantially blown (F2) blades (F2) and guided to an opening nip (N-) delimited by a drying cylinder and a drying wire (11). Method according to claim 1 or 2, characterized in that said blows (Fx) are applied to the region of the tip (K) of the scraper blade (14) at a distance L <250 mm at a pressure p - 50 ... 350 kPa, 30 when the nozzle holes of the blows (Fj) (23) diameters are of the order of 3-4 mm. A blowing device for carrying out the method according to any one of claims 1 to 3, integrated in connection with the scraper bars (12) of the drying cylinders (10; 10 '; 10A, 10B), the blowing device 35 comprising the end of the scraper bar (12) on the machine drive side a transverse nozzle tube 86900 11 (22) or a similar nozzle arrangement with a plurality of parallel nozzle openings (23) or a corresponding nozzle slot, characterized in that the blowing direction of said nozzles is aligned at a certain small angle (B) to the plane of the scraper blade (14) 5 to the region (K) of the tip acting against the surface of the drying cylinder, said nozzle tube (22) and its nozzle openings (23) extending transversely over substantially the entire width (Lx) of the headband and that said nozzle tube (22) is arranged so that its nozzles are located n. 100-300 mm, preferably about 200 mm, from the end of the scraper blade (14) 10 tips. Device according to Claim 4, characterized in that the scraper bar (12) has additional nozzles for directing additional air jets (F3, F *) towards the headband 15 (S) passing the scraper bar (12) as a support or free tension supported by the drying wire (11). . Device according to Claim 4 or 5, characterized in that the blowing device is arranged in connection with a scraper bar (12) whose perpendicular distance (S) of the scraper blade from the drying wire (11) passing past it or the corresponding free web pull (W „) is 150-500 mm, the distance (L) of the nozzle holes (23) from the tip of the scraper blade (14) is L <250 mm. 86900 12