FI82084C - Upper virus unit - Google Patents

Description

5,82084

Upper wire unit Övre viraenhet

The invention relates to an upper wire unit for the renewal of a fourdrinier wire section of a paper machine, comprising a frame structure and guide rollers mounted on it 10, one of which is a breast roll, and an upstream loop controlled by stationary shoe members cooperating with a lower wire so that the upper wire loop and the lower wire loop have a common run, in the region 15 of which an aqueous fibrous layer formed between said wires formed in the initial part of the lower wire before said common run is dewatered, in particular through the upper wire and the lower wire, substantially using stationary k inside the upper wire loop and a part inside the lower wire loop 20, of which the shoe members in the direction of travel of the wires of odd order are located in the lower wire loop and evenly inside the upper wire loop, the upper running of the upper and lower wire loops starting in the region of said first shoe member, the shoe members being positioned so as to direct the two-wire portion to pass substantially below the original plane of the upper wire section of the flat wire section.

The aim has been to develop a wire section of a paper machine of the hybrid-30 former type, i.e. one with a single-wire initial part followed by a two-wire part. This type of wire section known per se has been found to be able to achieve relatively high working speeds, but at the same time to be able to obtain high-quality paper.

The disadvantages of the previously known hybrid formers are mainly related to the wire flow control members used on the two-wire section, which at the same time act as dewatering members. These may be complex in structure and, in addition, may cause excessive wear of the wires, either through abrasion when the surface facing the wire is large or in some way discontinuous or uneven, or by such members causing relatively abrupt changes in the direction of the wire. .

It is an object of the present invention to provide an upper wire unit for the renewal of a fourdrinier section with which said drawbacks can be reduced.

10

With regard to the state of the art most closely related to the invention, reference is made to FI patent applications 822917 and 842918. prior art hybrid formers represented by the publications have a two-wire formation zone that is wavy. However, no attention has been paid in these publications to the ratio λ / Η of the two-to-15 wire forming zone (λ - the wavelength of the two-wire zone and the amplitude of the H-wave). However, in extensive test runs performed by the applicant on test paper machines, it has been found that in the range of said ratio λ / Η and related factors have a significant effect on web formation.

The upper wire unit according to the invention is mainly characterized in that said waveguide is gently undulating so that the ratio of the wavelength λ to the wave amplitude H is in the range λ / Η - 10-25, preferably 25 min λ / Η 12-20 and that said wavelength λ is in the range λ - 500-1000 mm and said amplitude H is in the range H - 35-60 mm, most preferably in the range H - 40-50 mm.

Em. In the prior art represented by FI applications 822917 and 822918, the said ratio λ / Η has always been clearly lower than 10, i.e. outside the widest range of the invention and most clearly outside the most suitable range of the invention λ / Η - 12-20.

In addition, in FI reference applications, the two-wire portion is always less than 35 single sine wavelengths. Instead, in preferred embodiments of the invention, the two-wire portion comprises substantially more than one

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3 82084 waves, up to about two full waves.

Em. The FI reference applications present the already well-established thinking that the two-wire forming zones are already known to design and when the invention substantially deviates from these ideas, certain advantages have been obtained.

In a preferred embodiment of the invention, only the first shoe is relatively wide and the subsequent shoe members each have a width of only 1/3 to 1/10 of the first. The fact that the first shoe is wider than the following does not pose a particular risk of wear of the wire, since in the area of the shoe in question most of the water removed from the web separates, which acts as a lubricant between the shoe and the wire.

15 In the solutions according to the FI reference applications, wide perimeter structures have been used, which are or may be partially covered with strips and thus also have a high wire consumption. It can also be stated that the FI applications in question using the members, the flow of wires in the two-wire section is not as smooth as in the preferred embodiments of our invention. Larger changes in direction in the common course of the wires also mean that the partially already formed fibrous web between them is subjected to shear-reducing shear forces.

The majority of the upstream dewatering is carried out in the invention in the region of the first closed shoe inside the lower wire loop, the size of the action sector of which is preferably adjustable by setting the position of the wire guide roll (chest roll). The width of the first shoe is usually about 300-500 mm. The first shoe is generally substantially capped and the radius of curvature of its cover is preferably »30 3000 mm.

In a preferred embodiment of the invention, the first shoe is followed by a second, narrower shoe inside the upper wire loop and connected to a water collection channel in the area of the first shoe to drain the outgoing water. The distance between the rear edge of the first shoe and the front edge of the second shoe 4 82084 is about 100-300 mm, preferably about 150-200 mm. Too big. the distance means that not enough outgoing water can be led to the water collection channel, but it leaves downwards.

5

The invention will be described in more detail below 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.

10

Figure 1 shows a schematic side view of a renewed fourdrinier wire section applying the method of the invention.

Figure 2 shows a top wire unit according to the invention in a schematic side-15 view.

Figure 3 shows a schematic side view of another forming part according to the invention.

The fourdrinier flat wire unit 10 to be renewed and improved according to Fig. 1 comprises a body part consisting of horizontal beams 23 and vertical beams 24 and 25. The flat wire loop 11 runs from the chest roll 12 in a horizontal plane TT with a drainage known per se inside the wire loop 11. include a chest 13 ', 25 flat boxes 13, 15 and 17, and foils 14,18. In the downward run between the rollers 19 and 20, the web W is detached from the wire 11 and transferred to the pick-up felt 21 by the suction zone 22a of the pick-up roll 22. The guide rollers 16 guide the return flow of the wire 11.

30 As noted above, renewals of flat wire sections have recently become more common, with the aim of either improving the quality characteristics of paper and / or increasing the production speed of a paper machine. For these and other purposes of the invention, according to Figure 1, an upper wire unit 30 is arranged substantially above its center above the fourdrinier wire unit 10, the body part 35 of which rests on the vertical beams 24.

The parameters affecting the operation of the upper wire unit 30 are best seen in Figure 2 82084. When using the upper wire unit 30 according to the invention, very minor modifications need to be made to the fourdrinier flat wire section 10 while its equipment remains largely unchanged. The changes are limited to removing from the central area of the flat wire section 10 e.g. 5 successive flat boxes and replacing them first is connected to a suction source (-10 P). A narrower shoe 43 fitted between the loops of the wire 11 is arranged in the middle of said curved surface (RltR5) shoes 41 and 45, which may resemble foil. The upper surface guiding the wire 11 of the middle shoe 43 is preferably a small distance H1 below the tangent plane of the shoes 41 and 45.

The wire loop 31 of the upper wire unit 30 is guided by the guide rollers 32, 33 and 34. At least the latter of the guide rollers 34 is provided with a drive 35. The guide rollers 32, 33 and 34 are provided with scrapers 37 as is known per se. Inside the loop of the upper wire 31 a drainage box 40 is arranged as a single unit, on the lower side of which are integrated narrow strips guiding the passage and 44, which will be located substantially midway between the respective dewatering members 41, 43 and 45 of the sub-wire unit. Thus, the distances L1fL2, L3 and Lj of the shoes 41, 42, 43, 44 and 45 operating in the two-wire forming zone to be added in the renewal are preferably substantially equal to each other. The radii of curvature R1, R2, R3 and R * are generally between 2000 and 4000 mm, preferably about 3000 mm.

One of the most important modes of action of the invention is that the direction of the dewatering through the wire 11 with the single-wire initial section is reversed 30, i.e. upwards, into the dewatering through the wire 31. For this purpose, the first shoe 41 is closed-ended, which forces the water to exit in the direction of the arrows F2 through the upper wire. The majority of the dewatering with the two-wire section in the area of the first shoe 41 is e.g. about 90%. In the area of the first shoe 41, the dewatering through the upper wire 31 is very essential for the overall operation of the forming part. Therefore, this dewatering portion is suitably arranged to be adjustable. To this end, the upper wire 31, the guide roll 32 is arranged in the direction of arrow S direction essentially vertical position, so that the twin-wire portion of the shoe 41 and a joint wrap angle a change.

5 The larger the angle α, the greater the proportion of dewatering through the upper wire 31 on the first shoe 41. If, for example, the radius of curvature Rj - 3000 mm of the first shoe 41 and the width 1Q is 300-500 mm, the angle α is e.g. between a = 2 ° ... 12 °. In order to adjust said coverage angle α, the first shoe 41 can also be arranged to be tiltable, i.e. to be rotated or even moved horizontally and / or vertically in the direction of its longitudinal axis. A solution for the devices required in this connection has already been invented in the applicant's above-mentioned FI patent 62873 - US patent 4,416,731.

According to the invention, the passage of the two-wire forming zone bounded between the lines K1 (K2 (Fig. 2)) is gently, substantially sinusoidally undulating, so that in the wave range H to 35-60 mm, the amplitude H is in the range H to 35-60 mm, preferably H - 40-50 mm The passage of the two-wire section starts from the solid cover forming shoe 41 with the tangent plane of its inlet edge 41 '20' being the original plane TT of the flat wire, then the two-wire zone curves downwards under the control of the shoe 42 and then curves upwards again as a narrow shoe The run of wires 11,31 then curves downward under the narrow shoe 44 of the upper wire unit 30, returning to its original plane TT under the control of the shoe cover 46 shoe 45. Although the shoes 42, 43 and 44 are quite narrow in the direction of travel of the wires 11 and 31, the two-wire portion consists entirely ofundulating due to dynamic forces. The dewatering pressure acting in the area of the shoe 41 in the two-wire forming zone is known to be Px to T2 / R1 (where T2 is the tension of the upper wire 31 (N / m). Correspondingly, the dewatering pressure P2 to T1 in the area of the shoe 42 (T2 The dewatering pressure in the area of shoe 43 is P3 to T2 / R3, the dewatering pressure in the area of shoe 44 P4 to T2 / R * and the dewatering pressure P5 to T2 / R5 in the vicinity of the initial edge of shoe 45. The tightenings Tx and T2 are

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7 82084 preferably in the order of 5-8 kN / m and radii of curvature RltR2, R3 and R4 in the order of 3000 mm.

Figure 3 shows an alternative embodiment of the invention, which is suitable for e.g. relatively thin paper grades. The embodiment of Fig. 3 differs from that of Fig. 1, first, in that its upper wire unit 30 is located quite close to the headbox 25. Thus, the single-wire initial portion 10a formed by the lower wire 11 is relatively short so that there are only two chests 10 13 "or the like. above the second is already in the upstream 31 breast roll Ia 32, which is a vertical direction S of the steering. 3, the two-viiraisella section of the figure is a two forming shoe, namely a relatively wide first umpikantinen shoe 41, which provides a number of significant high water removal direction of the arrow F j direction through the upper wire 31 15 and the box 40 ', since the relatively short single-wire initial portion 10a still has a considerable amount of water left to be drained, the rate of dewatering in the area of the shoe 41 is higher than mentioned above.The second shoe 42 is substantially narrower than the first shoe 41, which is list-like and which provides a "dip-20 pan" in the course of wires 11 and 31. The two-wire section then has flat boxes 46 against the lower wire 11, in the region of which the common run of the wires 11 and 31 returns very gently to the level of the upper wire T-T and which further supplement the dewatering. In the area of the latter box 46 and the subsequent flat box 17 ', the upper wire 31 separates from the lower wire. The planar box 17 'ensures that the web W follows the lower wire 11. In other respects, the structure and operation of the forming part shown in Fig. 3 is essentially as described above in connection with Figs. 1 and 2. In Fig. 3, the leveling boxes 46 'largely correspond to the forming shoe 45 with the strip cover 36 shown in Figs. 1 and 2.

30

In the following, the main features of the operation of the forming part according to the invention and the effect of various parameters on it will be described. The operation of the flat wire portion 10 is normal with the single wire initial portion 11a. The headbox 25 feeds the fiber suspension jet J to the flat wire section at the wire table 13 ', in the area and after of which the water is removed from the pulp mainly only by gravity and with the aid of dewatering equipment 13,14,15. The upper wire unit 30 and the two-wire forming zone defined by it are so arranged that at the initial line Kx of the two-wire section, the dry matter content of the formed fiber layer W „is of the order of 1% to 1.5%. If the dry matter content of the fibrous layer is substantially higher than this limit value when the fibrous layer falls within the scope of the upper wire unit 30, the objectives of the invention cannot be achieved, at least in all respects. This applies in particular to the effect of the upper wire unit 30 on the symmetry and formation of the web formed.

10 twin-wire forming zone K1-K2, first the leading edge 41 of the shoe 41 'slightly to remove water from the arrow Fx direction of action of the scraper. 41 the area of the shoe and the foililistan 42 and the area between the water is removed to a significant extent in the direction of the arrow F2, mainly in the upper wire 31 of the clamping pressure P3 due to centrifugal force boosted by. Yäviiran 15 through 31 in the direction of the arrow Fx removed water is discharged into the water kinetic energy (auto-slice effect) and into the water collection box 40 by suction (-P) impact of the channel 46 through the arrow V into the box 40 and from there onto the paper machine. The shoe 42 affected by the amount of clamping pressure between the wires 11,31 P2 essentially plane wire 11, 20 and the clamping Ti, wherein the dewatering takes place mainly in the direction of the arrow F3. The leading edges of the shoes 42, 43 and 44 may also have a scraping effect which removes water to some extent. of the lower wire 10 in connection with the shoe 43 of the influence of the amount of the tightening pressure of the upper wire between the wires 11 and 31 to 31 the tension T 2, causing drainage of the arrow 25 in the direction Fa, facilitated by the foil 44 past the leading edge of the scraper effect. The effluent water is thus transferred to the side of the wire section by means of a box 40 by means of kinetic energy and a vacuum effect (-P). In the area of action of the shoe 44, the tightening pressure is determined by the tightening T3 of the lower wire 11 and in the area of the shoe 45 the tightening T2 of the upper wire 31. The suction on the web W from the slots 46 between the strips 46 of the shoe 45 30 removes water and, above all, ensures that the web W follows the planar wire 11 as the upper wire 31 separates therefrom.

In Fig. 1, the upper wire unit 30 is located in the central region of the flat wire length L, 35. In embodiments such as Figure 1, the length L of the two-wire section compared to the total length L of the flat wire depends on many 9,82084 different factors nun. whether the purpose of the renewal is mainly to increase the speed of the forming part or mainly to improve the formation of the web, thus affecting the quality properties of the paper. In embodiments such as Figure 1, the length L is between 25-40% of the length L „, most preferably between 5-35%.

With respect to the dewatering portions, the single-wire initial portion 11a accounts for about 85% to 95% of the total dewatering, preferably about 90%. The twin-wire dewatering zone K d K i dewatering preferably 10 distributed in such a way that the direction of the arrow F2 to take place through the upper wire 31 of the water discharge portion concerning the twin-wire portion of the total water removal is very large approx. 80-95%, preferably approx. 90%. As shown by arrow F3 in the direction of the lower wire 11 through the dewatering of 5% and the direction of the arrow F * dewatering area proportion of the order of 15 L of water drainage on the order of 10% of the rest divided portions to the other.

The embodiments of the invention shown in Figures 2 and 3 above differ from each other in that in Figure 2 the two-wire water-20 drainage zone, guided by shoes 41, 42, 43, 44 and 45, has two waves, of which the first wave length is L2 + 1¾ and the second wave length is L3. + L4. In Figure 3, there is only one "wave" which is mainly defined by shoes 41 and 42.

According to the invention, the course of the two-wire run is substantially sinusoidal in the case of the shoes guiding it. It is very important for the purposes of the invention that the shape of said sine curve is suitably gentle. This fact is best illustrated by the ratio f - λ / Η, where λ - wavelength (from peak to peak) and wave amplitude H (altitude difference between peak 30 and valley). For the purposes of the invention, said ratio is f to 10-25, preferably 12 to 20. The length λ of said wavelength is preferably in the range λ to 500-1000 mm and the amplitude in the range is about 35-60 mm, preferably about 40-50 mm. The running of the two-wire zone differs somewhat from the sinusoidal wave, mainly because in the embodiment of Figures 1 and 2 35, the first and last shoes 41 and 45 inside the lower wire 11 are substantially wider than the second, koi 8 82084 mas and fourth shoes 42, 43 and 44. .

The corrugated biscuit wire forming zone is entirely below the base plane T-T of the lower wire, preferably even so that the guide surface of the narrow middle shoe 43 is a small distance Hx below the plane T-T.

The following are claims within the scope of which the various details of the invention may vary and differ from those set forth above.

Claims (4)

A top wire unit (30) for replacing a fourdrinier wire section of a paper machine, comprising a frame structure (35) and guide rollers (32, 33, 34) mounted thereon, one of which is a breast roll (32), and stationary shoe members. guided by a loop of an upper wire (31) cooperating with a loop of a lower wire (11) belonging to said fourdrinier wire portion on a portion (L) of the length (Lc) of this lower wire loop such that the upper wire loop (31) and the lower wire loop (11) have a single thread, in the region of which water is removed from both the upper wire (31) and the lower wire (11) substantially from the aqueous fibrous layer (Wc) passed between said wires (11,31) formed by the initial portion (11a) of the lower wire (11) before said common run; utilizing stationary shoe members (41,42,43,44, 15,4,4,4 '), part of which is located inside the upper wire loop (31) and part inside the lower wire loop (11), already of the shoe members (41,42,43, 44,45) in the direction of travel of the wires, odd-numbered are arranged inside the lower wire loop (11) and evenly inside the upper wire loop (31), the common running of the upper and lower wire loops 20 (11,31) (41) in an area in which the shoe members (41,42,43,44,45) are arranged in the height direction so that the two-wire portion is guided by their action to run below the initial plane (TT) of the upper course of the flat wire section in a substantially sinusoidal wave path, characterized in that the wave track is gently undulating such that the ratio of the wavelength to the amplitude H of the wave is in the range A / H to 10-25, preferably A / H to 12-20 and that said wavelength A is in the range A to 500-1000 mm and said amplitude H in the range H to 35-60 mm, preferably in the range H - 40-50 mm. 30 Upper wire unit according to Claim 1, characterized in that the width (L10) of the first shoe element (41) controlling the travel of the waveguide in the direction of travel of the wires (11, 20) is between L10 and 300 mm to 500 mm. 35 Upper wire unit according to Claim 1 or 2, characterized in that the second shoe element (42) controlling the travel of the waveguide is formed by at least one strip about 50 to 100 mm wide. Upper wire unit according to one of Claims 1 to 3, characterized in that the fourth shoe element (44) which controls the travel of the waveguide is formed by a strip about 40 to 70 mm wide. Il i3 82084 1. Ovre viraenhet (30) avsedd förnyande av fourdrinier-viradelen i en pappersmaskin, vilken enhet (30) innefattar en stomkonstruktion (35) 5 samt en Övre viraslinga (31) som är styrd av styrvalsar (32,33, (34) in the case of monolithic constructions of a four-dimensional structure (32), in the case of a four-dimensional rope (32), and in a stationary position, in the case of the head (Le) of the underside of the head set, Fig. 10 of the end of the head (31) and the end of the head (11) of the end of the head, the end of the head of the head (W0) next to this virus (11,31), vilket fiber-skikt bildats pä begynnelseandelen (11a) av den undre viran (11) förre nämnda gemensamma lop, bäde genom särskilt den övre viran (31) och den 15 undre viran (11) väsentligen genom utnyttjande av stationära skoorgan (41,42,43,44,45,46 '), in the case of a placardade in the presence of a spearhead (31) and in a plurality of a sphere in the field of a spearhead (11), in the case of a placebo (41,42,43,44,45) viraslingan (11) and head mot-20 weighing the same or more than the same number of viraslingan (31), varvid det gemansamma véget av de belts and nedre viraslingorna (11,31) börjar pä omrädet av detörsta scoorganet (41), vilka scores (41,42,43,44,45) are in the case of non-transferable placards, which have been replaced by a genome inverted to the end of the day (TT) in the 25 days of the end of the year at the end of the year sinusformad vägbana, kännetecknad därav, att vägbana är längsluttande väkig pä sädant sätt, att förhällandet mellan väglängden λ och vigorampliten omrädet A - 500-1000 mm, 30 och nämnda amplitud inom omrädet H - 35-60, siltpligast inom omrädet H - 40-50 mm. 2. The head can be set aside according to claim 1, the pivoting means being shown (L10) in the form of a scaling (41) with an end force of 35 times the force (11.20) of a pressure of L10 - 300 mm - 500 mm. i4 82084 3. The upper part of the head is shown in claim 1 or 2, the head of which is shown in the figure (42) when the end is shown at least 50-100 mm from the list. 5 4. The head can be seen in the light of patent patent 1-3, känne - t e c k n a t därav, att det fjärde scoorganet (44) som styr finished in a force of about 40-70 mm. of