FI97306B - Double-wire shapes of a paper or cardboard machine - Google Patents

Abstract

Viewed in the direction of travel of the wire (3), the slot nozzle (1) has a rear wall (6) having two horizontal parts (8 and 9). The upper part (8) is fixed in the operative position and the lower part (9) facing the wire (3) is shaped and arranged along the upper part as a shutter movable in relation to it and partly overlapping it and can be adjustably slid both towards the wire (3) and away from it. The part (9) is elastically supported in the set position towards the wire (3) on the upper fixed part (8). An adjusting motor (9) is arranged between the lower part (9) and the upper part (8) to move and elastically support the lower part (9). Arrangements of the slot nozzle (1) in a twin-wire former are described.

Description

97306

Double wire former for a paper or board machine

The invention relates to a double wire former for a paper or board machine according to the preamble of claim 1.

In particular, double wire formers use gaps, also known as Autoslice, to drain the circulating water of the suspension layer formed there between the wires upstream. In this case, when it is relatively easy to drain the circulating water downstream downwards by gravity alone, the drainage of the circulating water upstream must be carried out substantially perpendicularly upwards against gravity. Due to the kinetic energy of the water moving at the speed of the wire, the water rises along the wall of the slot-15 account of the slit nozzle and can be removed, possibly by means of a vacuum, from the upper wire and led elsewhere.

Various types of slit nozzles and their applications are already known, for example, from the following publications: In the double wire former according to EP 0 0 299 445, a long shoe is first placed on the lower wire. The circulating water above cannot be removed,, immediately from the upper wire by means of a slit nozzle located at the rear. In addition, the surface formation of the suspension cannot be improved by weight pulses.

DE-A-1 116 967 describes water-conducting elements and a nozzle which remove the circulating water upwards, but are not suitable for controlling the formation.

30 According to EP 0 136 000. . ·. primary and secondary Autoslice nozzles that are immobilized relative to the top wire, which can cause the deformable suspension layer to crush and be damaged. In addition, the distance of the slit nozzles upstream is considerable,; 35 which can lead to unwanted mist formation.

2 97306

PCT / FI86 / 00 012 describes a double wire former with slit nozzles projecting into a wire. There is also a risk of the fiber layer being crushed when using this type and mode of operation.

With the prior art as described above, it is an object of the invention to provide a clean and reliable upwardly operating slit nozzle, for example a dewatering unit with said slit nozzles, which makes it possible to produce a plurality of weight impulses acting on the surface of the sus-10 pension. the position of the slit nozzles relative to the upper wire, i.e. its position when the suspension layer between the wires is of different thickness, can be adjusted simultaneously automatically. To this end, it should be possible to apply the use of these slit nozzles relatively easily when converting a flat wire section of a paper machine to a double wire section. It should also be possible to use the slit nozzle advantageously also in the production of so-called heavy grades of paper or board (for example, corrugated board, corrugated board).

This object is achieved by means of a double wire former according to the characterizing part of claim 1.

Preferred embodiments of the invention are described in claims 2-10.

In the following, the object of the invention and the advantages achieved by it are described and explained in more detail. Description based on. : is a diagram showing:

Fig. 1 is an application example of a slit nozzle on a larger scale, Fig. 2 shows an example of double wire formers having slit nozzles according to the invention, and • · · '· *. Figure 3 shows another example in which: '· the position of the headbox is different.

The slit nozzle 1, which is used in particular in the twin-wire former 2 of a paper or paperboard machine 2, is primarily intended for discharging circulating water away from the upper wire 3 of the twin-wire former. It has a water-conducting space 4 located between two walls 5 transversely and 6. Seen in the direction of the wire run, the front wall 5 is here shorter in the direction of the wire 3 than the rear wall 6, which in its operating position extends to the wire 3, whereby a gap 7 is formed between the lower edge of the shorter front wall 5 and the wire 3. The rear wall 6 has two horizontal parts 8 and 9. In its operating position, the upper part 8 is fixedly in place and the lower part 9 facing the wire 3 is movable along the upper part, partially overlapping with it. This part 9 can be moved by adjusting it towards the wire 3 or away from the wire 3. The part 9 rests resiliently in its respective adjusted position towards the upper, fixed part 8 of the wire 3.

In order to move the lower part 9 and provide a flexible support, a control motor 10 is located between the upper part 8 and the lower part 9. In the embodiment shown here, the control motor has two pressure states 22, an upper pressure state 22 which moves the lower part 9 upwards and a lower pressure space 23 moves the lower part 9 downwards towards the wire 3. The spaces 22 and 23 are lined with tight 25 but flexible hoses which are pressurized by a pressure ·. * ·; question. The pressure provides a flexible support, • · · / ·: whereby the lower edge 25 of the lower part 9 facing the wire 3, provided with a wear-resistant material layer 24, can follow the position of the wire 3. This position 30 changes during use as the thickness of the suspension layer. . ·. changes. This adjustment is made automatically.

• · '.V. The water rises through the water-conducting space 4 and ««. flows into the collecting space 26, from which it flows out through the opening 27. Depending on the space always available, the collection space: 35 can be located either in front of or behind space 4.

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If necessary, the individual slit nozzles can be assembled into a single dewatering unit, which as a whole can likewise be adjusted in relation to the position of the wire.

Fig. 2 shows an example of a double wire former 2 with slit nozzles 1 according to the invention. It has a bearing surface determined by the position and shape of the support elements 11-13 or 14-17. These support elements are of a type already known and are intended both to lead the circulating water downwards and to produce pressure pulses on the lower surface of the suspension layer to be formed between the upstream 3 and the downstream wire 18, which runs along the support surface. Viewed in the direction of travel of the wires 3 and 18, at the beginning of the web-forming journey there are slot nozzles 1, 15 in contact with the upper wire 3 during use, in each case in the respective part of the slot behind element 11 or 12 or 13. The part provided with the slit nozzles 1 is followed in a known manner by a pressing shoe 19 •. provided part in which support elements 14 to 15 are placed at the pressing shoe 19 on the lower wire 18. The suspension is sprayed between the wires from the headbox nozzle 28 between the breast rollers 20 and 21. The upper breast roll 25 20 is a closed roll, the lower breast roll 21 is an open roll, V *: which receives water and discharges it.

• ·:: · Figure 3 shows another possible structure of the spray area, which has a headbox 28 'providing a substantially upward spray with a breast roller 30 21', in the centrifuge area of which the first suction nozzle begins to act.

• · Decision of circulating water carrying and weight impulses ««. the placement of the elements, slit nozzles, compression shoes, • support elements, moldings, etc., is at the discretion of 35 experts in the field. In the placement and selection of these elements 5 97306, several different combinations can be used, depending on the case to be solved in each case, i.e. always according to what is necessary and correspondingly advantageous. The same applies to the choice of support surfaces, 5 whether they are straight, wavy or descending.

Thus, it is also possible to realize a double wire former which differs from that described above in that, viewed in the direction of travel of the wires, it first has a compression shoe (such as 19) upstream followed by a point provided with slit nozzles (such as 1).

In order to speed up the implementation of such advantageous combinations, for example in the case of machine renewal, it is advantageous to use a support structure 29 to which the individual elements can in each case be fastened 15 or in which they can be moved.

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Claims (10)

1. Double-wire molds (2) of a paper or cardboard machine with an upper wire (3), lower wire (18) and slot nozzle (1) for draining circulating water from the upper wire of the mold (3), which nozzle has a water supply -current space (4) formed between two transverse wires (3) across the width of the wires (5 and 6), the front wall (5) of the wire having a distance to the wire, such that a slot (7) ) rises between the lower edge of the front wall (5) and the wire, the rear wall (6) preferably at its operating position all the way to the wire, and a guide surface located on the slit nozzle opposite the wires (3, 8). side, characterized in that the rear wall (6) in each set position is elastically supported in relation to the wire, and has two substantially arranged above each other and movable parts (8 and 9), the upper part (8) in operating position is stationary and the lower (9) facing member (9) is provided along the upper as an aperture to the slidable, partially overlapping mixer, which can be moved toward or from the wire. 2. Double-wire shapes (2) according to claim 1, characterized in that the guide surface is elastically formed. Double-wire molds (2) according to claim 2, characterized in that there is a setting for the position of the wires between the elastic slit nozzle and the • ♦. . elastic guide surface. 4. Double-wire forms (2) according to claim 1, characterized in that it has an adjusting motor (10) designed for displacement and as an elastic support. for the lower part (9). 5. Double-wire forms (2) according to claim 1, characterized in; characterized in that the lower edge (25) of the lower part (9) faces the wire (25) with a wear-resistant material layer (24). 10 97306 Double-wire molds (2) according to any of the preceding claims, with a predetermined supporting surface, by means and arrangement of supporting elements (11, 12, 13 and 14, 15, 16, 17), along which the wires, the upper wire (3) and underlays - the ridge (18) is brought with the suspension layer to be formed and dewatered, characterized in that a number of slit nozzles (1) in the running direction have been arranged in contact with the top wire (3) at the beginning of the forming distance, with always a slit nozzle (1) lies between 10 adjacent, at least part of the supporting elements (11 and 12 or 12 and 13) forming the guide surface, or in the running direction always seen behind a supporting element (11 or 12 or 13), a slotted nozzle section being followed by a press shoe (19) has a section, in which further supporting elements (14, 15, 16 and 17) are provided on the underwire (18) at the press cone (19). Double-wire molds (2) according to claims 1-5 having a predetermined supporting surface by means and shape of support elements (11, 12, 13 and 14, 15, 16, 17) along which the wires, the upper wire (3) and the lower wire (18) ), is carried with the suspension layer, which is to be formed and dewatered, characterized in that a section provided with press shoe (19) is provided at the beginning of the forming section, in which supporting elements (14, 15, 16 and 17) at press cones (19), which section is followed by a number of slit nozzles (1) such as ♦. . in each case has been arranged in contact with the overwire • · · *; ** (3), wherein a slot nozzle (1) is always located between two adjacent supporting elements (11 and 12 or 12 and 13). Double-wire forms (2) according to claim 6, characterized in that in the section provided with slot nozzles (1) there are chest rolls (20 and 21), of which the Upper (20) is a closed roll and the lower (21). ) an open, circulating water conductive drum. 11 97306 Double-wire forms (2) according to claim 4, characterized in that the actuator (10) has two pressure chambers (22, 23) which are lined with sealing hoses of elastic material which can be pressurized. Double-wire molds in a paper or cardboard machine having a plurality of slit nozzles according to claim 1, characterized in that a structural unit formed by a plurality of slit nozzles (1) can be set against a wire affected by this unit. • · • · · · · • ♦ • · • · «• 1