FI86445B - Profiling arrangement for the flow in the lip canal of the head box in a paper machine and/or board machine - Google Patents

Description

86445

Paper machine and / or board machine headbox lip channel flow profiling device

The invention relates to a lip channel flow profiling device for a paper machine and / or a board machine.

One previously known solution for the lip opening of a paper or board machine headbox is disclosed in FI patent publication 31 710. In this previously known solution, the upper or lower lip of the lip opening is provided with one or more flexible media-impermeable bags or housings extending directly into the lip. Said bags or cases in this prior art solution are intended to be filled with a medium and by changing the pressure of the medium in said bags or cases, or in one of them the profile of the lip is changed. In this previously known solution, the aim has been to replace the adjustable tip strip.

Multilayer headbox solutions with generally three separate lip openings are also known in the art. These previously known multilayer headboxes have sought to provide a paper web structure in which the outer layers of the paper web have a more expensive and within them a cheaper pulp. Adjusting the flow of the middle lip channel of such a previously known multilayer headbox has been very difficult to carry out, so that the structure of the middle mass layer has generally not been adjusted.

It is known to use a transverse jet of pulp suspension discharged from the headbox lip channel to the wire or into the gap between the wires. ; profiling top list and associated control spindles, which I .. are controlled by a process computer. The disadvantage of this control mode is its slowness, as settling and response times are typically in the order of several minutes.

The object of the invention is to provide a paper machine headbox flow profiling device with which it is possible to profile the flow already in the lip channel.

The object of the present invention is to provide a headbox flow profiling device which can be arranged substantially faster in operation than the previously known profiling systems based on tip strip adjustment.

It is also an object of the invention to provide a solution for controlling the flow of a headbox, which is also applicable to controlling the mass flow of the middle lip channel of a multilayer headbox.

In order to achieve the above and later objects, the paper machine headbox flow profiling device according to the invention is mainly characterized in that the profiling device is formed at the beginning of the headbox lip channel (s), at the end opposite the lip opening, or at the top of the lip channel (s). a profiling plate connected to the lower lip wall and a set of profiling members 20 connected thereto.

Other advantageous features of the invention are set out in claims 2-6.

The structure according to the invention facilitates the work of the top list of the headbox of a paper machine, since the solution according to the invention corrects the mass flow profiles already in the lip channel and the profiling according to the invention can be arranged substantially faster than known control methods.

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The solution according to the invention is also advantageously applicable to the middle layers of a multilayer headbox, in which case the top list of the multilayer headbox, which is often difficult to implement, can be omitted.

By means of the invention, it is also possible to improve the fiber orientation of the pulp flow, e.g. at the edges or alternatively in the middle, by performing the necessary profiling according to the situation.

86445 1 In the solution according to the invention, it is also possible to make intentional, regular transverse flows into the lip channels, whereby the level of the tensile strength ratio can be lowered with guitar formers, which can then also be used for making fine paper.

5

The invention can also be used to correct an oblique tensile profile using oblique profiling.

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 narrowly limited.

Figure 1 shows a machine direction vertical section of a headbox structure, in connection with which it is advantageous to apply the flow profiling device according to the invention.

Fig. 2 schematically shows the lip channel of a paper machine headbox equipped with a flow profiling device according to the invention. 2q application solution.

Fig. 2A schematically shows a partial section A-A of Fig. 2.

Figure 3 schematically shows a further application example of a profiling device according to the invention.

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Figure 4 schematically shows an application example of a flow profiling device according to the invention.

. 2Q Fig. 5 schematically shows a lip channel part of a multilayer headbox provided with an application solution of a flow profiling device according to the invention.

The headbox structure shown in Fig. 1 is mainly known from the prior art, and in the following its structure will be described as a background of the invention. The headbox pulp suspension jet J is fed to a forming wire 11 passing over the breast roll 10. The headbox comprises a pedestal structure 12, 4 86445 1 with a lower frame beam 13. Attached to the front wall of the beam 13 is a lower lip beam 14. 24 is bounded by an upper lip wall 14b associated with protective structures 28.

5 Through the lip opening 25, the pulp suspension jet J is fed to the wire 11 or to the gap between the wires. The lip opening 25 is limited and adjusted by the upper lip plate 26.

Massasuspenslo introduced into the headbox of a transverse manifold 15 jQ by means of which the flows are divided into a plurality of machine-directional distribution manifolds 16. The tubes 16 of the pulp suspension will equalizing chamber 17, on which the output side of a channel 18, which opens above the equalizing chamber. The equalization chamber has an air space V which acts as a damper for pressure fluctuations. In connection with the channel 18 there is a dam 18a, followed by an overflow 19a. The dam 18a sets the height C of the pulp suspension.

After the equalization chamber 17, a turbulence generator 20 follows, first in the flow direction, a perforated plate 21 with three overlapping rows of flow holes 21a. Each hole 21a opens into the turbulence tube 22 of the turbulence generator 20 20, which begins coaxially with its hole 21a. The turbulence generator 20 on the output side 23 of discharge currents of the slice channel 24, which continues to flow in the direction of the arrow F j huuliauk size of 25.

According to Fig. 2, the flow profiling device according to the invention is located in the lip channel 24. The profiling device comprises a profiling plate 30 and a series of profiling members 31 (Fig. 2A). The profiling plate 30 is attached to the slice channel ylähuuliseinämään 14b and 30, it is easy to be profiled by means of the profiling means 31 of the arrow S direction. Due to the hydrostatic pressure in the lip channel 30, the profiling plate 30 presses evenly against the upper lip wall 14b when it is not loaded by the profiling member 31. According to the invention, the profiling member 31 can load the plate 30 e.g. pneumatically, hydraulically or mechanically. The profiling device is attached immediately after the turbulence generator 35 to the beginning of the lip channel 24.

5 86445 1 The operation of the profiling device is controlled by a control system 35 connected to the profiling members 31, which is connected to the control system 36 of the tip strip 32.

According to Fig. 2A, the profiling device comprises a large number of profiling elements 3Ι ^, 312 · ..., 31n_2 »3n_i, 31 ^ arranged in succession in the transverse direction. The number of profiling members 31 ^, 312 · ..31 ^ depends on the width of the headbox. The profiling members 31 ^, 312 · ..31 ^ are preferably identical to each other and are preferably arranged at regular intervals in the transverse direction over the entire width of the lip channel 24 of the headbox. The distance L between the profiling members is in the range 30-120 mm, preferably in the range 60-100 mm. The profiling members 31j, 312 · ..31 ^ are controlled by a control system 35. According to the figure, the profiling elements 31 ^ ... 31 provide a corrugation to the profiling plate 30 of the profiling device.

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The operation of the profiling device according to the invention is based on the phenomenon that the corrugation in the lip surfaces causes differences in the transverse velocity profile of the pulp suspension flow, i.e. it affects the uniformity of the flow.

Fig. 3 shows an application example of a headbox flow profiling device according to the invention, in which the profiling plate 30. . connected to the profiling members 31 are rods which change their length in a magnetic field.

V. 25

In the embodiment of the invention shown in Fig. 4, profiling is achieved by adjusting the profiling plate 30 by means of a pneumatic pad 31. This profiling device according to the invention also has a flap 33 which prevents the fibers from entering the open gap 34 of the lip wall.

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Fig. 5 shows an application example of a profiling member suitable for a multilayer headbox, in which the profiling plate 30 is placed in the upper lip wall 14b of the middle lip channel 25. The plate is profiled by means of profiling elements 31, which in this application example are pneumatic pads.

The profiling plate 30 used in the above figures should be 6 86445 1 such that it is flexible enough for the pressure of the lip channel 24 to be sufficient to press it back against the lip wall 14b. This is advantageous because thus a unidirectional actuator can be used as the profiling member 31. The profiling device 5 according to the invention can also be formed in such a way that the profiling elements 31 are double-acting.

The profiling device according to the invention can be attached to the upper lip wall 14b or the lower lip wall 14a of the lip channel 24 and in multi-layer layer boxes to any lip channel 24.

The above figures show an embodiment of a profiling device according to the invention, in which the profiling plate 30 forms a step in the upper lip wall 14b. The height of the step from the surface of the upper lip-15 wall 14b is 0-10 mm, preferably 2-4 mm. In various embodiments, it is also possible to shape this point so that no step is formed, whereby the profiling plate 30 is e.g. flush with the surface of the upper lip wall or is connected to it by means of a chamfer.

The invention has been described above with reference only to some of its preferred application examples. However, this is in no way intended to limit the invention to these examples only, but many modifications and variations are possible within the scope of the inventive idea defined by the following claims.

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Claims (6)

1. Profiling device for the current in the lip channel of the inlet of a paper machine and / or cardboard machine, characterized in that the profiling device consists of a profiling plate (30) which is connected to the beginning part of the lip channel (24) at the opposite end of the relationship (25). to the upper lip wall (14b) and / or the lower lip wall (14a) of the inlet lip lip channel (24) / channels and of a series of profiling means (31lt 312 ... 31 ") connected thereto. 2. Profiling device according to claim 1, characterized in that the series of profiling means comprises a large group of profiling means (31lt 312 ... 31N) placed one after the other in the transverse direction, most preferably at 30-120 mm intervals, which means are most suitable are identical to each other and most preferably located at regular intervals (L) in the transverse direction over the entire width of the inlet and that said profiling means are arranged to be controlled by a control system (35). 20 3. Profiling device according to claim 1 or 2, characterized in that, with the series (31lf 312 ... 31H) of profiling means in the profiling device, cause vagueness in profile. The transverse disk (30) in the transverse direction of the papermachine, which A-comprise the corresponding differences in the transverse velocity profile of: the pulp suspension current in the lip channel (24). 4. A profiling member according to any one of claims 1-3, characterized in that the profiling member (31) in the profiling device is arranged to completely pneumatically, hydraulically or the disc. . mechanically. 5. A profiling device according to any one of claims 1-4, characterized in that the profiling means (31) consists of a rod 35: which changes the length of a magnetic field. ίο 86445 6. A profiling device according to any one of claims 1-5, characterized in that the profiling plate (30) is flexible so that the pressure of the lip channel (24) is sufficient to push it against the lip joint (14a, 14b).