FI86901B - Arrangement for controlling the paper-threading operation through a paper machine - Google Patents

Description

86901

Device on a paper machine under the control of a web headband

Anordning vid en pappersmaskin vid styrningen 5 av spetsdragningsbandet av banan

The invention relates to a device for guiding a web head conveyor belt 10 on a paper machine, which device is arranged in the area between the central roll of the paper machine press or the like and a separate press nip of the press part. from a guide roll, preferably a suction transfer roll, located in the vicinity of said center roll 15, in direct flow to said separate press nip.

As is already known, when starting a paper machine or after a web break, the end of the web is passed through the drying section by cutting e.g. a pu-20 cross against the central roll of the web with a water jet from the web narrow, e.g.

about 200 mm wide headband, ie the edge band, which was previously usually guided manually using air jets. The constant increase in the speed of paper machines has brought with it increasing difficulties in exporting the web head. These difficulties are at their worst immediately after the 25 press sections and in the initial drying section as well as in the group intervals of the drying groups.

With regard to the state of the art related to the invention, reference is made to the applicant's F1 patent 69145 and FI patent 78528 (cf. U.S. Pat. No. 4,923,567), in which an attempt has been made to solve the problems discussed above.

The latter FI and US patents disclose a method and apparatus for guiding and advancing a paper web headband from a smooth surface roll of a press so that the headband is detached from the smooth surface of the center roll and further guided using a baffle and air blows. An air jet having a sufficiently high impulse and sharpness is applied against the headband on the roll surface. With the air jet, the headband is cut off and its inlet direction 2 86901 nan end is removed from said roll surface by said air jet. The detached headband is guided for further control and transport by the transfer blow. The transfer fan is aligned along the guide plate. Due to the blowing in connection with the control plate, a vacuum field is created, as a result of which the headband is further guided in the direction determined by the control plate.

It is known to use press parts comprising a compact press roll combination with two or three adjacent press nips between which the web has a closed outlet. This is followed by a third or fourth separate press formed between the upper roller with a smooth surface and the lower roller with a hollow surface. Arranged through this separate nip is a lower felt, inside which said hollow bottom press roll is mentioned. The full-width web and the head-15 tin strip are guided from the smooth-surfaced center roll of the compact roll combination in a short free pull, usually through a guide roll, to the upper surface of said discrete nip felt.

On the upper roll of the separate press, a wreck conveyor and 20 scrapers are generally used to move the edge band tending to wrap around the upper roll in the transverse direction to the side. This waste conveyor is placed above the substantially horizontal run of the separate press felt, which run is guided by a suction transfer roller to the separate nip. In said run, immediately before the separate nip, a suction box 25 is also used, which ensures that the web and the headband remain on the upper surface of the felt. Below said wreck conveyor there is generally a wall which is substantially parallel to the flow of felt passing below it. Said wall and the direct felt flow define a gap between them, which is a difficult problem in head export due to the airflows induced therein and their dynamic pressure effects.

When the edge band is detached from the center roll when blown forward, the felt of the separate press does not stick, but air remains between the edge band and the felt. The detachment of the web from the felt is also facilitated by said strong air flow in the gap bounded by the felt and the bottom wall of the wreck conveyor, which tends to suck the web towards the bottom wall of the wreck conveyor 3 86901. These problems have worsened as paper machine speeds have increased.

These export problems are also exacerbated by the fact that in the headband control 5, the suction zone of the suction roll of the lower felt of the separate press cannot be effectively used to attach the headband to the lower felt. There are also problems with bagging due to the looseness of the headband and other similar problems that occur after the detachment from the center roll of the press.

10 Attempts have previously been made to reduce the slack of the headband after the center roll of the press by the speed difference of the felt of the separate press, but as the speeds of the paper machines increase, there is usually not enough room to increase the speed in this respect.

It is an object of the present invention to provide new solutions to the problems discussed above.

It is a particular object of the invention to provide a device for guiding the edge strip to the separate press, by means of which the edge strip 20 is adhered to the upper surface of the felt of the separate press so that the edge strip is loose as it comes out of the center roll of the press. The paper guide roll near the center roll can then be moved to the lower position and the web can be spread to full width with a bevel cutter.

In order to achieve the above and later objects, the invention is essentially characterized in that a transverse blow nip felt (said straight run is provided above it with a transverse blow tube or tubes from which blows in the opposite direction to the direction of travel of the felt and web are directed). into the gap between the straight run of the felt and the wall above it, and at the same time promoting the retention of the headband on the surface of the felt by said straight run before the separate press nip.

35 86901 4

In addition to the blows applied to the headband of the device according to the invention, various control and / or printing devices, such as air jets, a pressure plate or roller and / or a pressure tape around the swivel wheels, can be used on the inlet side of said shaft space. With said additional devices, the inlet end of said shaft space can also be closed, so that the amounts of air induced therein are substantially reduced.

In the following, the invention will be described in detail with reference to some application examples of the invention shown in the figures of the accompanying drawing, to the details of which the invention is in no way narrowly limited.

Fig. 1 shows a schematic side view of a press part provided with a separate press, in which the edge band guide device according to the invention is applied.

Figure 2 shows a schematic side view of a basic version of the device 20 according to the invention. Figures 2-5 are at the same time larger scale views of the area D marked in Figure 1.

Fig. 3 shows, in a manner similar to Fig. 2, a device according to the invention with a plate-like edge-25 tape printing device before the blowing devices.

Fig. 4 shows, in a manner similar to Figs. 2 and 3, a device according to the invention with a weight roller articulated to the support arm before the blowing members.

30

Fig. 5 shows, in a manner similar to Figs. 2 to 4, a device according to the invention with a press strip device before the blowing members.

Fig. F> shows a top view of the device according to Fig. 4.

35 5 86901

Figure 7 shows the blow pipe of the device according to the invention and its nozzle arrangement seen from the blow direction.

Fig. 8 shows the same as Fig. 7 seen from a direction perpendicular to the blowing direction.

First of all, an example of a press section in which the device according to the invention can be advantageously applied will be described with reference to Fig. 1 as a background and application environment for the invention.

10

The paper web W is introduced by the forming wire 10 to the pick-up point P, from where it is transferred on the lower surface of the upper felt 11 to the first press nip N1f which is double felt. After the first press nip Nr, the web W is transferred by said upper felt 11 to the second nip N2. After the second nip N2 15, the web W follows the smooth-surfaced central roll 12 of the press, in connection with which there is a third press nip N3 provided with a felt 13. After the third nip N3, the web W further follows the smooth-surfaced center roll 12, from which it is detached by the paper guide roll 15 and transferred to the lower felt 17 of the separate press by means of the suction zone 16a of the suction transfer roll 16.

After the suction transfer roll 16, a slightly oblique run of the felt 17 follows, by which the web W is introduced into a separate pressing nip N4 formed between the upper surface 25 and the hollow lower roll 26. After the separate nip N4, the web W is transferred, guided by a guide roll, to the drying wire 28 of the drying section, by which the web W passes around the heated drying cylinder blades 29a and the turning cylinders 29b in a serpentine path. The cylinders 29a and 29b are located inside the hood 29c of the drying section. The drying section shown above is only one example of a press section in which the edge band guide device according to the invention can be applied.

The application environment of the invention and the basic version of the headband control device R according to the invention will now be described in more detail with reference to Fig. 2. For example, a headband R about 200 mm wide is cut with a chamfer cutter (not shown) from one edge of the full width web W against the surface of the center roll 12 in a situation where the web W is removed from the surface of the center roll 12 with a scraper 14 blade and fed to the pulper below. Detachment blows from the nozzle tubes 19a of the blowing device 19 are applied to the edge strip on the surface of the cylinder 12 in the manner described in the above-mentioned FI patent 78528. At this point, the paper guide roll 15 is moved to the upper position 15 '. The guide plate 19b of the guide device 19 and the blows associated therewith guide and direct the tin strip R of the headrests-5 along the path Ri to the rear end of the suction zone 16a of the suction transfer roll 16. In order to cause the headband R to adhere to the surface of the separate press felt 17 in the area of the suction transfer roll 16 and to move smoothly to the separate nip N4, air blows F1-F2 from the nozzles 20a of the control device 20 are directed against the web W 10. The blow pipes 20 are fixed to the lower surface of the plate wall 21. The wall 21 is attached to the cross member 22 and to the frame structures of the wreck conveyor 23. The waste conveyor 23 known per se moves the separate press from the smooth-faced upper roll 25 in the transverse direction of the web W and / or the edge strip R removed by the scraper blade 23a to the side of the paper-breaker and further to the pulper.

According to Figs 2-8 the blow pipe 20 from nozzle openings 20a is applied to the edge strip R in relation to the direction of travel in opposite directions blowing En · Said blowing Fx is controlled by the wall 21 in the plane direction 20, so that the result of the felt-induced air flow 17 at folding back the arrow F2 direction while pressing the head of-tinauhaa R closely felt 17 against the top surface. Thanks to the blows F: the dynamic suction effect between the wall 21 and the edge strip R is eliminated and the edge strip R is made to settle and adhere 25 to the surface of the felt 17.

to engage the upper surface of the felt 17 of the roll 16 in the suction zone 16a of the second 30-side region: Figure 2 in accordance with the blow tube 20A, which is applied in the direction of the arrow F3 blowing with a threading strip R is used for the wall 21 at the side of the inlet. Before the separate nip N4 there is a suction device 18 inside the loop of the felt 17, which ensures that the headband R and the track remain on the surface of the felt 17 as it enters the nip N *.

When, as described above, the headband R! the passage to the separate nip 35 N * has been established, the paper guide roll 15 'is moved to its normal position 15, where it forms a transfer nip Ns with the suction transfer roll 16 7 86901. Prior to the above transfer of the roll 15, the loose strip 12 has been loosened and passes along the path R2 sideways of the roll 15 '. When the transfer nip Ns is closed, the headband R follows the transfer nip Ns of the roll 15, followed by the vacuum of the suction zone 16a of the suction roll 16, 5 press felts 17, which are maintained by blowing F1 (F2 and F3).

According to Fig. 3, instead of or in addition to the first blow pipe 20A, a pressure plate device 30 is used, the pressure plate 32 of which is arranged to pivot about a horizontal joint 30a by means of an actuator 31. Ballast-pressure plate 32 along the bottom edge to the tail R suction zone 16a of the suction roll 16 in the second side region. Once the headband Rx has been attached to the upper surface of the felt 17, the pressure plate 32 can be turned to the upper position 32 'by the actuator-15a 31. A small blow F * can be provided on the track side surface of the printing plate 32 to prevent the headband R from adhering to the surface of the plate 32. The retention of the edge band R on the surface of the felt 17 in the nip NA ceases in the region of the gusset K by the blows Fj-F2 and the suction box 18 described above.

20

According to Fig. 4, a weight roller 33 placed on the inlet side of the groove K is used, the cylinder shell of which is perforated, wire- or wire-faced and / or grooved. The roller 33 is mounted on an arm 35 which is attached to the flange of the beam 22 by a horizontal rivet joint 36. The arm 35 rotate and 25 loads the actuator 34. The threading strip R is pressed a roller 33 of the suction zone 16a of the second half region of the felt against the 17 upper surface, after which the threading strip R adheres to the felt 17 on the surface, where it remains puffs F1-F2 and imulaaatikon 18 allows erillisnippiin N * up. When the travel of the headband R has been stabilized, the roller 33 is raised 30 by the actuator 34 to the upper position 33 '. The roller 33 can be arranged to rotate freely or be provided with its own drive to rotate it at the speed of a paper machine or at a slightly higher speed. The roller 33 and the plate 32 shown in Fig. 3 contribute to preventing air induction in the friction K.

35 s 86901

According to Fig. 5, a press tape device AO is placed at the beginning of the shaft K. The device AO comprises a body part 38 on which the end rollers AOa.AOb are mounted. Arranged around the end rollers AOa.AOb is, for example, a printing tape 37 of a width of about A00 mm, which is preferably a wire-like 5 air-permeable fabric. A blowing box can be arranged inside the printing tape 37, where the prevailing overpressure allows air to be blown downstream of the printing tape 37 to prevent the edge tape from sticking to the printing tape 37. The device AO is connected to an actuator A2 for turning the device around the horizontal joint 39 to position 37 ', in which case the device AO is in the inoperative upper position. The rollers AOa.AOb can be equipped with their own drive motor or traction wheel, which takes the rotational movement from the surface of the felt 17 or the roll 15. When the edge band Rj is blown by blows from the blow tube 19a into the converging gap G 15 between the press band 37 and the felt 17, air escapes between the edge band Rj and the felt 17 and the edge band Rx is pressed against the felt 17. At the same time, the edge band Rt can be pressed against the surface of the felt 17 with the printing tape 37.

Figures 6, 7 and 8 show the locations of the blow pipes 20 and other devices 20, as well as an example of the construction of the blow pipes 20. The length L of the blow pipes 20 is substantially greater than the width 1¾ of the edge strip. According to Fig. 6, air is introduced into the blow pipes 20 in the direction of arrows A from fans known per se (not shown). As shown in Figures 7 and 8, the nozzle holes 20a of the blow tube 20 are in a row and the other end 20b of the tube 20 is closed. The diameter d of the nozzle holes 20a is e.g.

d = 1-2 mm, the pitch Lo of the nozzle holes is e.g. L0 - 10-20 mm, the length L of the nozzle tube 20 is e.g. L - 1000-1500 mm and the length Li of the part provided with the nozzle holes 20a is e.g. Lx - 600-1000 mm and the diameter D of the nozzle tube 20 is e.g. D - 20-30 mm.

30

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

Claims (10)

9 86901 A device on a paper machine for controlling a web (W) head guide strip (R), which device is arranged in the area between the central roll (12) or the corresponding press nip (N4) of the press section of the paper machine, the separate press nip (N4) being formed between the lower roll (26), around the lower roll (26) of which the lower felt (17) of a separate press is arranged to run from a guide edge (16) placed in the vicinity of said central roll (12), preferably from a suction transfer roll (16 ', 16a) to said separate press nip (N4), characterized in that a transverse blow pipe or pipes (20) are arranged above said straight run of the felt (17) of the separate press nip (N4), from which the direction of travel of the felt (17) and the web (W) is aligned. 15 den opposite blows (Fx) to reduce air induction of the felt (17) above and above that straight run to the gap space (K) between the wall (21) and at the same time promoting the retention of the headband (R) on the surface of the felt (17) by said straight run thereof before the separate press nip (N4). 20 Device according to claim 1, characterized in that said nozzle tube or tubes (20) are attached to the lower surface of the lower wall (21) of the wreck conveyor (23) operating in connection with the upper press roll (25) to extend beyond the width (L *) of the headband (R). . 25 Device according to claim 1 or 2, characterized in that a transverse blowing pipe (20a) with nozzle openings for air blowing (F3) is attached to the inlet edge of said shaft space (K) at or near the front edge of said upper wall (21). (RL) is pressed towards the suction zone (16a) of the suction transfer roll (16) at the felt (17) of the separate press (Fig. 2). Device according to any one of claims 1 to 3, characterized in that said blowing tubes (20) are successively two in the vicinity of the central region of said straight felt flow (17) above it. 10 86901 Device according to any one of claims 1 to 4, characterized in that a printing plate device (30) is arranged on the inlet side of said shaft space (K), comprising a printing plate (32) pivotable around the horizontal joint (30a) by an actuator (31). (Rj) can be pressed against the felt (17) of the separate press (Fig. 3). Device according to any one of claims 1 to 4, characterized in that a weight roller device comprising a hinge arm (35) or a corresponding freely rotating or driven weight roller (33) is arranged on the inlet side of said shaft space (K) above the path of the headband. the headband (R) is pressable against the surface of the separate press felt (17) as it passes over the suction zone (16a) or the like of the suction transfer roll (16) and the weight roller (33) of the weight roller is loadable 15 and move to the inoperative upper position (33) ') (Figure 4). Device according to any one of claims 1 to 4, characterized in that a printing tape device (40) is arranged on the inlet side of said shaft space (K), comprising a printing tape (37) 20 extending over the end rollers (40a, 40b), inside which a blow box, said press tape device (40) being attached to an actuator (42) by which the press tape (37) can be pressed against the felt (17) of the separate press to press the headband (Rj) onto the upper surface of the felt (17) and by means of the actuator (42) is pivotable with its straps (37) to the inoperative upper position (37 ') (Figure 5). Device according to any one of claims 5, 6 or 7, characterized in that said printing plate device (30), roller device 30 (33-35) and / or tape device (40) contribute to closing said gap space (K) the input side so that the induction of air into said shafts (K) is eliminated or at least substantially reduced. Device according to one of Claims 1 to 8, characterized in that a paper guide roll (15) is arranged between the guide device and the smooth-surfaced central roller (12) of the press, from which the headband (R) is removed by blowing (FA). (15 ') and after head removal to a normal lower position, where said paper guide roll (15) forms a transfer nip (Ns) with a suction transfer roll (16) of a separate press lower felt (17) and that said transfer nip (Ns) is followed by a suction transfer roll (16a) ) and then a substantially direct flow of said felt (17) to a separate press nip (N4). Device according to one of Claims 1 to 9, characterized in that before the separate nip (N4) there is a suction box (18) or a corresponding suction device arranged inside the loop of the felt (17), which secures the headband (R) and / or the web (W). remaining on the surface of the felt (17) as it enters said separate nip (N *). 15 12 86901