FI83978C - FOERFARANDE OCH ANORDNING I INLOPPSLAODAN AV EN PAPPPERSMASKIN FOER REGLERING AV DEN TVAERRIKTADE HASTIGHETSPROFILEN AV MASSASUSPENSIOSSTROEMMEN. - Google Patents

Description

83978

The present invention relates to a method , the headbox comprising a manifold and / or a turbulence generator, the turbulence generator and / or manifold using a plurality of parallel flow cells in which the pulp suspension flow from the compensating chamber or manifold is divided into different streams the inlet side of the flow ducts of the flow cross surfaces of the head parts is adjusted so as to provide a different flow resistance of the ducts I do not divide -20 ma in the transverse direction of the headbox, so that the desired transverse velocity profile is obtained for the lip channel flow of the headbox and the lip jet discharged from it through the lip opening.

The invention furthermore relates to a paper machine headbox for carrying out the method according to the invention, comprising in the flow direction of a pulp suspension a manifold or in a multilayer headbox manifolds and a manifold or manifolds and then adjacent overlapping flow cells and each headbox comprises a lip channel (s) through which the pulp suspension flow is arranged to discharge onto the forming wire or between the wire forming rolls, and wherein control rods or extensions of which have been introduced through the flow suspension of the pulp suspension and connected to the actuators.

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It is known from the prior art to aim for a uniform cross-section of the machine direction velocity in the lip flow of the headbox pulp suspension. It has also been known that a detrimentally high transverse velocity may occur in said flow. Especially in the edge areas of the track, this has been a disadvantage, for example in the form of edge wave reinforcement.

A steady speed of lip flow is sought in order to make paper homogeneous in width, shape and strength properties over the entire width of the web and to minimize the need to cut off the edges of the web.

In order to achieve the mentioned requirements, it is already known to use e.g. a solution in which a small part of the mass flow is removed through each side wall of the headbox lip channel before it is discharged onto 15 wires (e.g. FI patent No. 43812, Beloit Corporation). The opposite solution, in which an additional flow of water is led through the side wall, is also known (FI patent no. 30095, Valmet Oy), but the latter solution has not been implemented in practice, at least by the applicant.

The present invention relates in some respects to the methods and apparatus disclosed in Applicant's FI patent applications 844276 and 850638 in a paper machine headbox for controlling the skew of the fiber orientation of a paper web.

25 One problem with headboxes used with kitformers is the adequate stiffening of the lip area within the limited space of the forming crystal. This problem has become even more pronounced as paper machine speeds increase.

The main object of the present invention is to eliminate the above-mentioned drawbacks and to provide a solution to the above-mentioned tasks and problems.

It is a further object of the invention to provide such a headbox adjustment arrangement with which it is possible to correct orientation errors of the lip jet, especially in the edge areas of the web.

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It is a further object of the invention to provide such a control arrangement apparatus which is also suitable for use with a thick-mass headbox.

The method according to the invention is mainly characterized in that the sets of control rods formed of individual or most overlapping control rods used in the process are moved by actuators mainly in the flow direction of the pulp suspension.

The headbox according to the invention, on the other hand, is mainly characterized in that with said actuators for adjusting the flow resistance profile, the position of the adjusting rods in their axial and machine direction relative to the mouth portions of the different flow cells is arranged to be adjusted separately in the cross-machine direction.

When applying the method of the invention in the production of multilayer paper, the adjustment of the basis weight profile over the entire width of the headbox can be made particularly advantageously by means of a middle layer so that the basis weights of the surface layer or layers can be kept constant and thus the best possible paper printability.

Although the most preferred applications of the present invention are in the manufacture of multilayer paper or board, the invention is also applicable and offers certain advantages in single ply headboxes.

In other formers, the control device according to the invention, which acts over the entire width of the headbox, can replace the previously known profile control devices which adjust the cross-section of the lip opening by means of a tip strip. In this case, the space saved by the tip strip adjustment can be utilized by improving the mechanical structure and / or the lip can be brought closer to the wire groove and thus the length of the lip jet can be made even shorter, which in itself improves the web formation.

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In addition, the control arrangement according to the invention can advantageously also be used to control the flow and fiber orientation of the edge region of the web, e.g. with planar or hybrid formers.

5 It should be emphasized in this connection that reducing the flow rate of the lip jet at a certain point in the web surprisingly causes an increase of substantially the same basis weight, albeit generally over a wider area of the web than where the flow rate is reduced, e.g.

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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 not limited.

Figure 1 shows a method and a headbox according to the invention applied to a multilayer web using a vertical grit former.

Figure 2 shows an application of the method and headbox of the invention in a single layer kit.

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Figure 3 shows a schematic side view of an embodiment of the invention in a single-layer former, e.g. a planar or hybrid former.

Figure 4 shows another embodiment of the invention in a planar or hybrid former.

Fig. 5 shows on a larger scale than Fig. 4 the adjustable throttling area between the adjusting rods according to the invention and the perforated plate of the turbulence generator.

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It should be noted at the outset that Figures 1 to 4 show machine direction vertical cross-sections of headboxes according to the invention, in which the methods according to the invention are applied.

Figure 1 shows a multilayer headbox with which a web is formed from three different pulp layers fed. The web is formed by wires 11A

li 5 between 83978 and 11B. The wires 11A and 11B form a forming crystal G between the breast rollers 10A and 10B, into which lip jets J are fed from the headbox through the lip openings A.

The multilayer headbox shown in Figure 1 comprises manifolds 12A.12B, 12C with manifolds 13A, 13B, 13C followed by turbulence generators 14A, 14B, 14C with a series of flow bores 15 through which mass suspension flows enter the tubular batteries 16A of the turbulence generator 16A. , 16C. From said tubular radiators, the mass suspension-10 flows into the lip channels 17A, 17B, 17C, which are bounded on the outside by planar lip walls 19A.20A and walls 19b, 19c therebetween. As part of the outer wall 20A, a lip beam 20 is attached to the headbox body 25 by a horizontal joint 18. The lip beam 20 is arranged to be pivoted about the joint 18 15 by means of a screw gear 21. The various structures of the headbox are fixed to a frame part 25, which is fixed to the base structures 23 by horizontal articulated shafts 22, which in turn rest on the foundations 50 of the paper machine room. The frame structure 25 is arranged by screw gears 24 to be rotated about the articulated shafts 22. The screw gears 24 are located between the base structures 26 attached to the foundations 50 of the projections 27 and 20 of the frame structure.

The middle layer of the web is fed from the middle distribution support 12B through the flow channel 13B, 14B, 16B, 17B and the surface layers of the web from the outermost distribution supports 12A.12B. On the inlet-25 side of the bores 15 of the turbulence generators 14A.14B.14C, devices according to the present invention are provided for adjusting and controlling the transverse velocity profiles of the mass jets. The said adjustment devices comprise adjustment rods 30, which preferably is connected to each of the turbulence generator 14 of each bore 15 of the inlet side of the mouth portion. The control rods 30 are located inside the housing portions 40 delimiting the back channel of the pulp suspension. The control channels 30 are led through sealed bushings outside said housing parts 40 and flow channels. The control rods 30 are connected in groups, in Fig. 1, in pairs to parts 31 fixed on the arm 32 to sets of control gears 33A, 33B.33C with a plurality of adjacent control gears 35 for adjusting the discipline between the bore portions 15 and the conical tips 30a duct choke (Fig. 6 83978 5) and thus its flow resistance. In this way, the transverse flow velocity profiles of the different flow channels of the multilayer headbox are affected. As the tip portion 30a of the control rods 30 is moved closer to the mouth of the bores 15, the flow resistance increases at this point and the velocity of the flow-5 decreases, and at the corresponding point a larger square cross-sectional area is observed in the web due to transverse flows.

Figure 1 shows all three headbox flow channels equipped with -10 transverse profile control devices according to the invention. However, the invention can also be applied in multilayer headboxes, e.g. in such a way that only in connection with the surface layer manifolds 12A and 12C and the associated pulp suspension flow channels there are transverse profile control devices according to the invention with the middle layer or layer headbox 15 without profile adjustment devices. When profile adjustment devices are used in the middle layer according to Fig. 1, the adjustment of the basis weight of the web is performed by adjusting the middle layer and the profile adjustment device of the surface layers ensures that the surface layers of the web are as homogeneous and even as possible. The profile adjustment devices in the web edge regions 20 can be used to control specific problems in the web edge regions, such as fiber orientation distribution problems.

The headbox according to Fig. 1 does not need a top strip in connection with the lip opening A at all, because the adjustment of both the transverse profiles and the basis weight can be performed with the profile adjustment devices connected to the turbulence generator according to the invention.

According to Fig. 1, the set of control gears 33A, 33B, 33C is controlled by the control system 100, from which the sets of control signals SA, SB, SC are obtained. Measuring devices 110 are connected to the control-30 system, which comprise, for example, measuring devices for a square weight profile traversing in the transverse direction of the web.

Although the most preferred applications of the invention are in multilayer headboxes, the invention can also be applied to single layer headboxes in both kit formers (Figure 2) and planar or hybrid formers (Figures 3 and 4).

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The headboxes shown in Figures 2 and 3 comprise manifolds 12 having an upwardly directed manifold 13 and then a turbulence generator 14 having said bores 15. The bores 15 communicate with tubes of tube coils 16 which open into a lip channel 17 with different tube flows. merge into a uniform lip channel flow. Through the lip channel, the pulp suspension jet J is discharged into the forming chuck G or on the wire 11 passing over the breast roll 10.

The headboxes according to Figures 1, 2 and 3 have a tip strip 28 in connection with the lip opening A. The profile of which is adjusted by means of adjusting arms 29 by means of screw gears 29a. According to Figure 2, the body portion 25 of the lower lip structures of the headbox is connected to the base structures 25 by a horizontal joint 22. In the headbox of Figures 3 and 4, the structures 25 of the lower lip frame 15 are fixed.

According to Fig. 2, control rods 30 are arranged in the intermediate chamber 40 of the pulp suspension flow channel, which are connected via overlapping rods to the same vertical part 31. The parts 31 are connected via a shaft 32 to control 20 gears 33 controlled from control system 100 by control signals S. The control rods 30 operate as described above, throttling the flow cross section of the mouth portions 15 of the bore 15 of the turbulence generator 14 through their conical mouth portions 30a.

As shown in Figure 3, the manifolds 13 of the manifold 12 open into an intermediate chamber 41 which communicates above the duct 42 with the air space V of the pressure equalization tank 43. The tank 43 has a dam 44 defining the free surface P of the pulp suspension. The control rods 30 in the same vertical row are connected to a vertical plate 34 , which is connected along the 32 to the control gear 33.

Figure 4 shows a headbox of a flat or hybrid former, in which a profile adjustment device according to the invention is arranged in connection with the manifold 12. The manifold 12 is provided with an outwardly open recess portion 12a into which the adjusting arms 32 are fitted. The control arms 32 are connected to vertical portions 31 each having a series of overlapping control rods 30, the conical portions 30a of the tips 8 83978 of which are in connection with the mouth portions 15 of the turbulence bores 15 in the front wall 14A of the manifold 12. Said turbulence bores 15 open into a tube coil 16, the separate mass suspension flows of the tubes of which are connected in a lip channel 17. In other respects, the headbox 5 shown in Fig. 4 and its profile adjustment devices are as described above.

Figure 5 shows on a larger scale the throttling area between the control rods 30 according to the invention and the mouth portions 15 of the bore 15 of the turbulence generator 14, where the conical tips 30a of the control rods 30 restrict the mass suspension flow f to the bores 15.

The invention can also be implemented differently from the above in several different ways, e.g. so that instead of the rods 30 connected to the common cross-section, a throttling lamella is used, e.g. having a flat end face 15, which, as it approaches the bores 15 of the perforated plate 14, straps a plurality of bores 15 which overlap. Various combinations of adjusting lamellae, adjusting plates and adjusting rods can also be applied within the scope of the invention.

In general, the method and apparatus according to the invention can be applied in headboxes in which the pulp suspension flow is divided into several parallel and possibly overlapping flow cells into partial flows, in particular for microturbulence, and which are then assembled in a lip channel. According to the invention, control rods are preferably used which are arranged on the inlet side of said separate flow cells, preferably on the inlet side of the boreholes of the turbulence generator. The invention preferably uses control rods which are movable for adjustment by screw gears 30 or other similar mechanical control devices, mainly in the plane of the flow direction of the pulp suspension. In this way, control devices are obtained which cause as little fouling problems as possible, which are generally due to the accumulation of fibers at the points where the flow cross-sections of the pulp suspension flow paths change.

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Although the invention has been described above with reference to an implementation example using an automatic control system 100 and an associated measuring system 110 for measuring web cross-sections, the invention can also be applied by connecting overlapping rows of control rods 30 or 5 each to a separate control screw. can be set manually, eg with the palm of your hand. In this way, both the basis weight and the adjustable cross-sections according to the invention can be controlled manually in the multilayer headbox. Of course, the invention can also be implemented as a combination of various manual -10 adjustments and automatic adjustments.

The following is an example of the effect of the profile adjustment device according to the invention obtained as a result of a theoretical examination. With the profile control devices according to the invention, the flow rate is reduced by 3 3% of the flow cross-section between the parts 15 and 30a, strangling a certain point in the web in a range of 120 mm wide. This stepwise reduction in the flow rate results in an increase in the basis weight of the web of about 3.5% for the corresponding web site and the effect extends over a range of about 350 mm in width.

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 (7)

A method in an inlet slide of a paper machine, the inlet slide comprising a lip channel (17) from which deC ejects a pulp suspension (J) pk the wire (11) or into a forming gap (G) bounded by the wires , said inlet sheath comprising a distribution pipe system (13) and / or a turbulence generator (14), employing in the turbulence generator (14) and / or the distribution pipe system (13) a group of parallel flow passages (15, 16) in which the mass suspension current 10 from the equalization chamber (40, 41) or the distribution boom (12) will be divided into partial streams which are joined to a lip channel stream, and in which method the flow transducers of the orifice portions of the inlet side of the various flow passages of the turbulence generator (14) and / or distribution tubes (13). ) is regulated in such a way as to allow such a distribution of the flow resistance in the various passages in the direction of the inlet side to the desired transverse velocity profile in the lip tread (J) flowing out of the lip channel current of the inlet side and thereafter via the lip opening (A), characterized by the fact that an individual or a series of control rods formed by several control bars located ( 30) used in the method are moved with functional devices (33; 33A, 33B, 33C) mainly in the flow direction of the pulp suspension to control the flow transducer area and the resistance of the orifice portions of the separate flow passages (15, 16) by the turbulence generators and 25 (13). Method according to claim 1, characterized in that the method uses a control system (100) which provides a series (S) or series (SA, SB, SC) of control signals with which the operating devices (33; 33A; 33B; 33C) of said control rods (30). A paper machine inlet designed to perform the method of claim 1 or 2, which includes the flow direction of the pulp suspension including a distribution boom (12) or distribution bars 35 (12A, 12B, 12C) in a multi-layer inlet slide and a distribution tube system (13). 13A, 13B, 13C) and then any turbulence generator (14,15) or optional turbulence generators (14A, 14B, 14C), and in which distribution pipe system (13) and / or in which turbulence generator (14) or generators (14A) -C) is a group adjacent to each other on flow passages (15, 16) and which inlet comprises a lip channel (s) (17A, 17B, 17C), via whose lip opening (A) the pulp suspension stream is arranged to flow out on the forming wire (11) or a forming gap (G) confined between the wires (11A, 11B, 11C) and in which it enters the pre-distribution pipe system (13) and / or the turbulence the generator (14) in the flow channel (s) of the pulp suspension is provided with a group of control rods (30) which, or extensions thereof, have been retracted outside the flow channel of the pulp suspension and connected to the functional devices (33; 33A, 33B, 33C). , for controlling the flow resistance profile with said function devices (33; 33A, 33B, 33C) the layer on the control rods (30) is arranged so that in the axial direction of these and in the machine direction in the relation to the orifices, the different flow passages (15) can be controlled separately in the transverse direction of the paper machine. 4. An inlet according to claim 3, characterized in that said control rods (30) comprise a rounded or conical tip portion (30a) arranged in communication with the orifice portion of said flow passage (15) so that the flow resistance on the input side of the different flow paths (15). ) can be controlled in the transverse direction of the paper machine. 5. Device according to claim 3 or 4, characterized in that said control rods (30) are arranged in a dispensing chamber (41) between the distribution pipe system (13) and the hollow discs of the turbulence generator (14), via said control rods (40). (30) is moved outside the flow channel and the tip portions (30a) of said control rods (30) are arranged in communication with the orifice portions of the inlet side of each other and parallel bores (15) of the hollow disc of the turbulence generator (14) to be controlled in the axial direction by the The bores (15). tl is 83978 6. Inlet according to claim 3 or 4, characterized in that said control rods (30) are arranged in connection with the orifices of the bores (15) of the housing plate in the anterior wall of the distribution box (12) and that the control rods (30) are carried therewith. - 5 lines outside the distribution boom (12) and connected to control devices or to manually operated control screws (Figure 4). Device according to any of claims 3-6, characterized in that the padded control rods (30) are connected to a common cross-section (41), which is connected with a control shaft (32) or the corresponding to a manual control screw or functional devices. (33), which is controlled by a control system (100) and that, in the place of the rods connected to a common cross section, a lamella is used, whose front end surface thrusts to several halves so that it resembles the base plate, which halves drive one another.