WO1998031874A1

WO1998031874A1 - Method and equipment concept in the cutting and threading of the lead-in strip of a paper/board web in the final end of the dryer section of a paper/board machine

Info

Publication number: WO1998031874A1
Application number: PCT/FI1998/000019
Authority: WO
Inventors: Tuomo Juvakka; Pekka Matilainen
Original assignee: Valmet Oy
Current assignee: Valmet Technologies Oy
Priority date: 1997-01-17
Filing date: 1998-01-13
Publication date: 1998-07-23
Anticipated expiration: 1999-07-17
Also published as: FI970196L; FI105937B; FI970196A0

Abstract

The invention concerns a method and an equipment concept in the cutting and threading of the lead-in strip (20) of a paper/board web in the final end of the dryer section of a paper/board machine. In the method the paper or board web (W) is passed over drying cylinders (K1, K2,...) and suction cylinders (S1, S2,...) further while meandering in loop shape. The lead-in strip (20) is cut by means of a cutter (10) before the last drying cylinder (K4) in the group (Rn). After cutting, the lead-in strip (20) is passed onto said drying cylinder (K4) and further from the drying cylinder (K4) onto the suction cylinder (S2). From the suction cylinder (S2) the lead-in strip (20) is passed further onto a guide roll (E, E10, E20).

Description

Method and equipment concept in the cutting and threading of the lead-in strip of a paper/board web in the final end of the dryer section of a paper/board machine

The invention concerns a method and an equipment concept in the cutting and threading of the lead-in strip of a paper/board web in the final end of the dryer section of a paper/board machine.

From the prior art, so-called Tail Shooters are known, i.e. a solution of equipment in which, after the cutting of the lead-in strip, the lead-in strip is guided by means of separate blowings in a free gap into a rope gap formed by ropes, being transferred further in the paper machine. Thus, said Tail Shooter equipment picks up the lead-in strip from the doctor of the last drying cylinder and shoots it over a pick-up plate and a transfer plate into the rope gap. For different paper grades, said blowing of the lead-in strip into the rope gap requires different set values. In order to avoid said problem, in the present patent application, a novel type of threading of the lead- in strip is suggested for the final end of the dryer section.

From the prior art, various threading devices are also known which pick up the web from a doctor. In said devices, mechanical cutting of the lead-in strip is employed in combination with different types of blowing or with a device for the transfer of the lead-in strip. Said transfer device may further be based on a vacuum sucked under the lead-in strip. As a rule, a problem of all of the devices that pick up the lead-in strip from a doctor is the slackness arising in the strip, which slackness requires a rather high difference in speed between the dryer section and the subsequent unit for the time of threading. Said difference in speed must then be reduced after the strip has become sufficiently tight in order that the strip should not be cut off. In the present patent application, it is suggested that the lead-in strip is cut towards the end of the dryer section by means of a cutter, which is preferably a water cutter, before the last drying cylinder. The lead-in strip thus formed is transferred onto an upper drying cylinder and guided by means of various blowings into a lower position into connection with a suction cylinder, preferably a so-called Vac Roll, placed in said lower position. A Vac Roll is a cylinder construction, out of whose interior free from suction boxes a vacuum is applied to the entire interior space in the cylinder and further through the perforations in the cylinder mantle to grooves provided on the cylinder face, in which grooves the holes passing through the mantle terminate at one of their ends. The grooves are preferably annular grooves which pass circumferentially on the cylinder face. In this way the web can be kept in contact with the wire face by means of the vacuum applied through the wire.

In the solution in accordance with the present invention, when the lead-in strip comes from the upper drying cylinder K₄ onto the lower suction cylinder S₂, the run of the lead-in strip is supported, in the way described above, by applying a blowing to the lead-in strip and by pressing it into contact with the wire face. In connection with the suction cylinder, the lead-in strip adheres to the suction cylinder, to the wire drawn over said cylinder. The lead-in strip is passed further upwards, preferab- ly supported by air blowings, onto the guide roll E. Before the guide roll, there is a rope draw, and said rope draw is preferably placed in connection with the guide roll so that the gap between the ropes of the rope draw T_{1 ;}T₂ is placed at the inlet side of the roll E, in which case, by means of the blowing L2, the lead-in strip is guided to the side into the rope gap C placed at the side of the roll and further, between the ropes T_j,T₂, for example, to the reel-up F.

In the construction in accordance with the invention, the guide roll E can also be a roll provided with a vacuum block and with a pressure block, in which case the rope gap can be placed after said roll. In such a case, by means of the vacuum block of the guide roll E, the lead-in strip is picked up out of connection with the wire H_j and, having been separated by the pressure block in the guide roll E, the strip is transferred further and, shifted by lateral blowing, into the rope gap placed after the guide roll E and by means of the rope draw, for example, to the reel-up.

The method in accordance with the invention for threading the lead-in strip of a paper and board web is mainly characterized in what is stated in the patent claims.

The invention will be described in the following with reference to some preferred embodiments of the invention illustrated in the figures in the accompanying drawings, the invention being, yet, not supposed to be confined to said embodiments alone.

Figure 1 A shows an embodiment of the invention, in which the dryer section concept comprises formation of a lead-in strip in accordance with the invention and transfer of said strip further and out of connection with the group of drying cylinders.

Figure IB illustrates cutting of the lead-in strip before the drying cylinder K₄.

Figure 1C illustrates the transfer of the lead-in strip into connection with the guide roll E.

Figure ID illustrates the blowing that supports the lead-in strip and that is produced by means of an air jet L_j applied from the beam of the doctor placed in a position below the drying cylinder K₄. The figure further shows a blow beam placed at the opposite side of the wire, a vacuum being produced at said side of the wire by means of the blowing applied from said beam, and a holding force in itself known being applied by means of the vacuum to the lead-in strip through the wire.

Figure IE illustrates blowing of the lead-in strip into the rope gap right before the guide roll E.

Figure IF illustrates the forming of the rope gap ahead of the guide roll E. Figure 2 shows an embodiment which is in other respects similar to Fig. 1A, but in which the locations of the suction cylinders and the drying cylinders as compared with Fig. 1A are inverse: the suction cylinders are placed above and the drying cylinders below in the group.

Figure 3 shows an embodiment of the invention in which the web is carried in the other respects in a way similar to the preceding embodiments, except that in this embodiment the guide roll E includes vacuum and pressure blocks and perforations passing through the roll mantle at said blocks, in which connection, by means of the suction applied through the vacuum block, the lead-in strip is picked up from the face of the wire, and by means of the blowing applied by means of the pressure block, the lead-in strip is separated from the guide roll, in which connection it can be transferred, by means of the lateral blowing applied after the guide roll E, into the rope draw Tr ,T₂ placed after the guide roll, into the rope gap C formed by its ropes T₁,T₂. After this the lead-in strip runs by means of the rope draw further between the ropes T_j,T₂.

Figure 4 shows an embodiment of the invention in which the guide roll E is conventional and the wire is passed over the guide roll onto the wire alignment roll D. The lead-in strip is supported on the wire run between the guide roll E and the wire alignment roll D by keeping the strip in contact with the lower face of the wire Hi by means of a vacuum. After the guide roll D the web is transferred into the rope gap between the ropes T and T₂ and further, for example, to the reel-up. The lead- in strip 20 can also be passed as a ropeless draw so that it is guided on support of blowings from the wire guide roll D to the reel-up.

Figure 5A is an illustration in part of the guide roll E.

Figure 5B illustrates an embodiment of the guide roll E₁₀ which includes a vacuum block and a pressure block. Figure 5C illustrates a second embodiment of the guide roll E₂₀ and of the transfer of the lead-in strip.

Fig. 1A shows a first preferred embodiment of the invention. In the dryer section 100, the last group R_n of drying cylinders shown in the figure comprises the drying cylinders Ki ,K₂,K₃ and K₄. As is shown in the figure, the suction cylinders S and S₂, i.e. the so-called Vac Rolls, are placed in lower positions. The second drying cylinder K₂ is placed in the construction slightly below the level of the suction cylinders. The web W is passed onto the first drying cylinder K_j in said group R_JJ of drying cylinders. The wire H is passed onto the drying cylinder Ki to its upper position and, along with the face of the drying cylinder, onto the wire alignment roll Di placed between the drying cylinders Ki and K₃ and further onto the drying cylinder K₃ and from it onto the suction cylinder S_j and further in the group.

The paper/board web W is passed from the drying cylinder Ki onto the lower drying cylinder K₂, and it runs as pressed against said cylinder and supported by the outside wire H₂, which is passed over the guide rolls gι,g₂ and g₃. From the drying cylinder K₂ the web W is passed into the nip between the drying cylinder K₃ and the wire H_j, from which the web is passed onto the lower suction cylinder Si , along whose face it runs by the effect of the vacuum produced in the interior of the suction cylinder S_{1 ;} which vacuum is further applied as a web holding force through the perforations in the mantle of the suction cylinder. Preferably, the suction cylinder S_j comprises grooves on its face, in which grooves the holes in the mantle terminate, and through the grooves a rather wide circumferential holding force is applied to the web W guided on the outside. From the suction cylinder Si the web W is passed along with the wire ϊiγ onto the fourth drying cylinder K₄ and further, meandering in loop shape, from said drying cylinder K onto the lower suction cylinder S₂, which is similar to the suction cylinder S_j described above. From the suction cylinder S₂ the web is passed further onto the paper guide roll E and from it further to the reel-up F. Of course, the last group in the dryer section may also consist exclusively of single- wire draw. The preferred arrangement of formation of the lead-in strip in accordance with the invention as shown in Fig. 1A comprises a cutter 10, preferably a liquid cutter and most appropriately a water cutter, in the position B_j between the suction cylinder S_j and the drying cylinder K₄. Thus, the lead-in strip 20 is cut in the position Bi by means of the cutter 10. Thus, the cutter 10 is preferably a liquid cutter and most appropriately a water cutter. It applies a pressurized water jet against the face of the web W to be cut. The web portion adjacent to the lead-in strip is transferred into the pulper after the cylinder K₄ by means of the doctor 11, whose blade 11a is fitted to be pressed against the lower face of the drying cylinder K₄. In connection with the doctor 11 , the air jet L_j, a so-called doctor jet, produced from the blow nozzle 50 and the blow beam 12, which is fitted at the opposite side of the wire H_j , which produces a vacuum at said side of the wire, and which is in itself known, support the transfer of the lead-in strip 20 further onto the suction cylinder S₂, by means of whose vacuum the lead-in strip, which was cut by means of the cutter 10, preferably a liquid cutter, is transferred further along with the face of the suction cylinder S₂ and transferred by means of the air blowing L^ (Fig. IE), into the rope gap C formed by the ropes T_} and T₂ and placed after the Vac Roll S₂ at the inlet side of the paper guide roll E. The common rope path of the ropes T_f ,T₂ is passed into the rope groove placed at the end of the paper guide roll E. The rope path of the ropes Ti and T₂ passes up to the reel-up F. Thus, the lead-in strip 20 is carried between the ropes Ti and T₂ up to the reel-up F.

Fig. IB is a more detailed illustration of the position B_j of the water cutter in accordance with the invention between the suction cylinder S_j and the drying cylinder K₄. The lead-in strip 20 is cut by means of a water cutter 10 in the way shown in Fig. IB. In the way illustrated in Fig. 1C, the lead-in strip 20 is carried onto the drying cylinder K₄ and from it further onto the lower suction cylinder S₂ and further onto the paper guide roll E.

Fig. ID is a more detailed illustration of said threading of the lead-in strip. After the cutting in the position B_j has taken place, the lead-in strip 20 is carried along with the wire Hi onto the upper drying cylinder K₄ and from it further downwards, in which connection an air jet L_j is applied from the doctor 11 through the blow nozzle 50 against the face of the lead-in strip so as to press the strip against the wire Hi . By means of the blow box or suction box 12, a vacuum is produced at the opposite side of the wire H, and by means of the vacuum the running of the lead-in strip 20 is thus supported. The web itself, adjacent to the lead-in strip 20, is passed down through the gap between the last drying cylinder K₄ and the last suction cylinder S₂ from the last drying cylinder K₄. Preferably, at the opposite side of the wire H_j, there is a blow beam 12, through which an air jet is produced along the face of the wire Hi , and further, thereby, a vacuum is produced at said side of the wire. In this way a holding suction or holding force is still applied by means of a vacuum through the wire Hi to the lead-in strip 20. The lead-in strip 20 runs further in connection with the lower suction cylinder S₂, by means of the vacuum produced in the suction cylinder S₂, in contact with the wire face and meandering upwards onto the paper guide roll E, the lead-in strip being blown into the rope gap C placed in connection with said paper guide roll E between the ropes Ti and T₂ by means of a separate blow nozzle 21. The blow air jet L2 shifts the lead-in strip 20, in relation to the longitudinal direction of the machine, towards the side into the rope draw T_{1 ;}T₂ placed at the side of the run of the web and the wire.

Fig. IE shows an embodiment of the transfer of the lead-in strip into the rope gap C related to the construction of Fig. 1A. The blowing 1^ of air is applied from the blow pipe 21 to the lead-in strip 20 from the middle area of the web run in the machine towards the side. In such a case, the lead-in strip 20 is shifted towards the side into the gap C between the ropes Tι ,T₂ shown in Fig. IF and further onto the paper guide roll E and further up to the reel-up as carried by the rope path Tι ,T₂ between the ropes T_j and T₂. Fig. IF illustrates the formation of the rope gap C by means of the ropes T and T₂.

Fig. 2 shows an alternative drying cylinder concept, which is in other respects similar to the concept shown in Fig. 1A, but in which the locations of the drying cylinders and suction cylinders are different. The suction cylinders Si and S₂ are placed at the top and the drying cylinders K_{1 ?}K₂,K₃ and K₄ at a level below them. The arrangements of cutting the lead-in strip and passing it into the rope gap C are, in the other respects, the same as those in the embodiment shown in Fig. 1A.

Fig. 3 shows an embodiment of the invention in which the paper guide roll E₁₀ is provided with an inner vacuum block or vacuum sector and with an inner pressure block or pressure sector placed after the vacuum block (as viewed in the running direction of the web). In said embodiment, the paper guide roll comprises perforations in the roll mantle, through which perforations either a pressure or a vacuum is applied to the lead-in strip 20 (depending on the block). The vacuum block and the pressure block can be placed at an end of the paper guide roll. Of course, an embodiment is also possible in which the whole paper guide roll, across its length, is provided with a vacuum block and a pressure block.

In the embodiment of Fig. 3, the arrangements of cutting and supporting the lead-in strip up to the forward side of the roll E are similar to the embodiments shown in

Figs. 1A...1F. The embodiment of Fig. 3 differs from the embodiment shown in

Figs. 1A...1F expressly in respect of the construction of the paper guide roll E₁₀ and in the respect that, for the transfer of the lead-in strip 20, at least before the paper guide roll E₁₀, no rope path or rope draw is used, but the lead-in strip 20 is transferred from the suction roll S₂ onto the upper paper guide roll E₁₀, which comprises a vacuum block 22 and a pressure block 23. The lead-in strip 20 is transferred further from said paper guide roll E₁₀ provided with said pressure arrangement to the rope draw Ti ,T₂, which is placed after the pressure zone of said paper guide roll E_i0- In said arrangement, the blow sector has been fitted so that said blowing, besides separating the lead-in strip, also prevents winding of the strip or, if the blowing has been extended to the entire length of the roll, also winding of the web around the paper guide roll E₁₀.

Fig. 4 shows an embodiment of the invention which is in other respects similar to the embodiment shown in Figs. 1A...1F, but in which the wire Hi is passed from the paper guide roll E₂₀ further onto a wire guide roll D. Thus, in the solution the wire H_j is fitted to run over the paper guide roll E₂₀ onto the wire guide roll D, in which case the web W runs between the guide roll E₂₀ and the wire H_j . In such a case, the lead-in strip 20 is also transferred from the suction cylinder, i.e. the Vac Roll S₂, into the gap between the paper guide roll E_2Q and the wire Hi and further along with the face of the wire H_j , being supported by the vacuum and, thus, by the holding force produced by the blow box/boxes 25, onto the wire guide roll D. In said arrangement, the paper guide roll, which includes a suction-blow zone, preferably comprises a doctor 24 on its lower face, which doctor prevents winding of the paper web around the paper guide roll E₁₀. A separate rope draw Tι ,T₂ may be placed in the vicinity of the wire guide roll D, or the lead-in strip can be passed further by means of support blowings produced from blow nozzles, in which case the threading can be a so-called ropeless threading in its final stage, e.g. to the reel- up area F.

Fig. 5 A is an axonometric illustration partly in section of a guide roll E which has been mounted revolving. The roll E comprises bearings Gi ,G₂, on whose support it is fitted revolving. The roll mantle E' is connected with the shafts n_j and n₂, on whose support the roll E revolves.

Fig. 5B shows an embodiment of the guide roll E₁₀. In the illustration in Fig. 5B, the guide roll E₁₀ comprises a vacuum block 22 and a pressure block 23 at its end. The blocks have been formed by means of partition walls 100,101 ,102 and 104, and the roll mantle E₁₀' includes a perforation in its face at least in the area of the blocks, in which connection, through the perforation 103, which holes 103 extend through the roll mantle, a holding suction or a detaching blowing is applied to the lead-in strip, depending on the block. The roll mantle provided with a perforation is connected to shafts n^n^ which have been mounted by means of bearing means G_j and G₂. In the embodiment of Fig. 5B, the blocks 22 and 23 have been formed at an end of the roll. An embodiment is also possible in which the blocks 22 and 23 have been formed across the entire length of the roll.

Fig. 5C shows an embodiment of the guide roll E₂₀. As is shown in the figure, the construction of the guide roll E₂₀ is similar to that of the guide roll E₁₀. As is shown in the figure, the lead-in strip runs between the wire H and the face of the roll mantle E₂₀' of the guide roll E₂₀ and further, for example, by means of a vacuum that has been produced from the opposite side of the wire. In the way shown in the figure, the vacuum is produced by means of a blow box 25 in itself known.

Claims

1. A method in the cutting and threading of the lead-in strip (20) of a paper/board web in the final end of the dryer section of a paper/board machine, in which method the paper or board web (W) is passed over drying cylinders (K_j,K₂...) and suction cylinders (S₁,S₂...) further while meandering in loop shape, characterized in that the lead-in strip (20) is cut by means of a cutter (10) before the last drying cylinder (K₄) in the group (R^), and that, after cutting, the lead-in strip (20) is passed onto said drying cylinder (K₄) and further from the drying cylinder (K ) onto the suction cylinder (S₂), in which connection the lead-in strip is held by means of the vacuum present in the interior of the suction cylinder (S₂) in contact with the wire (H_j) face on said web/wire draw, and that from the suction cylinder (S₂) the lead-in strip (20) is passed further onto a guide roll (E,E₁₀,E₂o)-

2. A method as claimed in claim 1, characterized in that, in the method, a water cutter is used as the cutter (20), and that the web portion adjacent to the lead-in strip, i.e. the web, is run down before the last suction cylinder (S₂), i.e. a so-called Vac Roll.

3. A method as claimed in claim 1 or 2, characterized in that, in the method, the lead-in strip (20) is guided between the last suction cylinder (S₂) and the guide roll (E) so that the lead-in strip (20) is transferred by means of an air blowing (L^) into the rope gap (C) of a rope draw (T_j,T₂) placed in connection with the guide roll (E), preferably ahead of said roll, and further by means of the rope draw (T_{1 ;}T₂) out of connection with the group (R_n) of drying cylinders, e.g. , to the reel-up (F).

4. A method as claimed in claim 1 or 2, characterized in that the guide roll (E₁₀) comprises a vacuum block (22) and a pressure block (23), in which connection the lead-in strip (20) is made to adhere, by the effect of the vacuum block (22), into connection with the roll mantle (E₁₀') of the guide roll (E₁₀), and said strip is separated from the guide roll (E) by means of the pressure block (23).

5. A method as claimed in the preceding claim, characterized in that the lead-in strip (20) is transferred into the rope gap (C) of the rope draw (T_j,T₂) placed after the guide roll (E₁₀) and further by means of the rope draw (T_j,T₂).

6. A method as claimed in claim 1 or 2, characterized in that the wire (Hi) runs along with the face of the guide roll (E₂₀) and as turned by said roll further onto a wire alignment roll (D), the lead-in strip (20) being transferred from the suction cylinder (S₂) between the guide roll (E₂₀) and the wire (H_j) and further, being supported by a vacuum and/or by means of suction, along with the lower face of the wire (H_j) and along with the wire onto the wire alignment roll (D).

7. A method as claimed in the preceding claim, characterized in that, in connection with the wire alignment roll (D), there is the rope gap (C) of the rope draw (T_j,T₂), the lead-in strip (20) being transferred into the rope gap (C) of the rope draw (T_j,T₂) and further by means of the rope draw (T, ,T₂), for example, to the reel-up (F).

8. A method as claimed in claim 6, characterized in that the lead-in strip (20) is transferred from the wire alignment roll (D) further as so-called ropeless threading.

9. An equipment concept in the cutting of the lead-in strip of a paper/board web in the final end of the dryer section of a paper/board machine, in which equipment concept the web is passed over drying cylinders (K_j,K₂), preferably steam-heated drying cylinders, and over suction cylinders ( ,S₂), which suction cylinders include a perforation on their faces, the web being kept in contact with the suction cylinder (S, ,S₂...) by means of a vacuum applied to the interior of the suction cylinder, characterized in that, before the last drying cylinder (K ) in the group (R_n) of drying cylinders, the equipment comprises a cutter on the wire and web run between the suction cylinder (S ) and said drying cylinder (K₄), and that, in the area between the drying cylinder (K ) and the suction cylinder (S₂), the equipment concept comprises devices (50,12) for supporting and/or guiding the lead-in strip (20) along with the wire, and that in the equipment concept the cut lead-in strip (20) is sup- ported when it moves from the drying cylinder (K₄) onto the last suction cylinder (S₂), and that, after the last suction cylinder (S₂), the equipment concept comprises a guide roll (E,E₁₀,E₂o), onto which the lead-in strip is transferred from the suction cylinder (S₂).

10. An equipment concept as claimed in claim 9, characterized in that the devices (50,12) for supporting the lead-in strip (20), which are placed in the area between the drying cylinder (K₄) and the suction cylinder (S₂), comprise a nozzle (50) that produces a blowing of air (L_j) and/or means that produce a vacuum behind the wire, preferably a suction or blow box (12), in which connection, by means of the blowing of air (L_j) and/or by means of the means that produce a vacuum, the cut lead-in strip is supported and/ or guided in the area between the drying cylinder (K₄) and the suction cylinder (S₂).

11. An equipment concept as claimed in claim 9 or 10, characterized in that the cutter (10) is a liquid cutter and preferably a water cutter.

12. An equipment concept as claimed in claim 9, 10 or 11, characterized in that the guide roll (E) comprises the rope gap (C) of a rope draw (T₁ ,T₂) at its forward side, devices being provided by whose means a transfer blowing (L^) is applied to the lead-in strip in order to transfer the strip into the rope gap (C) of the rope draw (T_{l 5}T₂), and that the rope gap (C) is placed at the forward side of the guide roll (E).

13. An equipment concept as claimed in claim 9, 10 or 11, characterized in that the guide roll (E₁₀) comprises a vacuum block (22) and a pressure block (23), in which connection a holding force is applied to the lead-in strip (20) through the vacuum block and through the perforation (103) in the roll mantle (E₁₀')_> and a pressure is applied to the lead-in strip (20) through the pressure block (23) and through the perforation in the roll mantle in order to separate the lead-in strip out of connection with the roll (E₁₀).

14. An equipment concept as claimed in the preceding claim, characterized in that the rope gap (C) of the ropes (T ,T₂) is placed directly after the guide roll (E₁₀).

15. An equipment concept as claimed in claim 9, 10 or 11, characterized in that the guide roll (E) turns the wire onto the wire alignment roll (D), in which connection the web is transferred from the cylinder (S ) onto the guide roll (E₂₀), the web being transferred between the face of the roll mantle (E₂₀') of the guide roll (E₂₀) and the wire (Hi) and running further from the guide roll (E^_Q) onto the wire alignment roll (D), in which connection, on the draw between the wire alignment roll (D) and the guide roll (E₂₀), the web is kept in contact with the wire face by means of a vacuum produced at the opposite side of the wire and/or by means of support blowings applied to the lead-in strip (20).

16. An equipment as claimed in the preceding claim, characterized in that the rope gap (C) of the rope draw (T_{1 ;}T₂) is placed after the wire alignment roll (D).

17. An equipment concept as claimed in claim 15, characterized in that the equipment for guiding the lead-in strip after the wire alignment roll (D) is a ropeless draw.