FI110196B - A method and apparatus for controlling a paper machine cross section in a former papermaking machine - Google Patents

Description

I 110196 Vol

Method and apparatus for controlling a paper machine's cross-sectional profile in a paper machine former Förfarande och anordning Päre formare av en pappersmaskin för control av pappersbanans tvärprofil 5

The present invention relates to a method for controlling the transverse property profile of a paper web to be made in a web forming section of a papermaking machine, wherein the transverse property profile of and / or the fiber orientation profile is realized.

The invention further relates to devices for carrying out the method of the invention.

Several forming elements are used in the forming parts of the paper machine. The main purpose of these elements is to provide compression pressure and pressure pulsation to the fiber layer that is formed to promote dewatering of the forming web while improving its

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formation. Said forming members include various forming shoes, generally with a * 25 curved molded cover over which the upper; the pile forming wires and the web between them are curved.

·; ··· In the area of these forming shoes, water is drained through the wire on the outer side j due to its clamping pressure and this drainage; ·, and is further assisted by a centrifugal force field. Dewatering also occurs through a wire on the inner side of the · · · 30 curve, which is usually enhanced by the forming. vacuum in the chamber of the pain shoe. The forming shoe * · · "* mold cover provides a pressure pulsation that both promotes dewatering and improves web formation.

* * · I "'; 35 In addition, so-called so-called "spin-offs" are known. MB units passing through *. usually in a straight run, two opposing wires. Within the second wire loop of known MB units, there is a pressure loading unit with load strips, and within the opposite second wire loop 2 110196 is a dewatering unit with a support and dewatering list. As is known in the art, the MB unit in question is located; is usually applied to the flat wire section so that the MB unit is noticeably preceded | a long single-wire portion with a substantial amount of dewatering before the web passes in a straight run in the flat wire plane S through the MB unit. The details of the known MB units are referred to by way of example in the applicant's FI patent applications 884109 and 885607.

As is known in the art, paper machine formers generally control the cross sectional profile of the paper web by adjusting the lip of the headbox lip. The purpose is to produce a uniform basis weight of paper so that the narrowest portion of the paper web is cut off.

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It is also known to adjust the transverse consistency profile of a fiber suspension jet discharging from the lip of the headbox. In this regard, we refer to Applicant's Divorced FI Patent Application Nos. 946180 and 946181 (filed 901593, filed October 20, 1991, respectively). For consistency profiling, reference is also made to J.M. Voith

GmbH DE Applications 3514554 and 4019593.

In the prior art, reference is also made to Applicant's FI patent applications • 932793, 942027 and 943909. Em. FI applications disclose methods for: * 25 paper machines for controlling the transverse property profile (s) of a paper web. In these methods, the transverse deflection of the dewatering and / or forming strip or strips is controlled and thus the transverse retention profile of the paper web is affected. By controlling the deflection of the dewatering and / or forming strip or strips, the transverse fiber orientation profile and / or filler profile of the paper web is controlled by controlling the transverse retention profile of the web. The methods of the latter FI applications are precisely characterized by the fact that they are applied in a two-wire zone having opposing lists. Equipment in this area must be very carefully fitted in tight spaces, which are also · susceptible to water leaving the web and soiling. The devices implementing this 3,111,096 method also become quite complex in their implementation and have high accuracy requirements for their adjustments. Even the known devices do not actually affect the tension profile of the forming wires.

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Various retention agents are also used in the formation of the paper web, the purpose of which is to control the water retention or retention of the fiber of the paper web. In DE-4237309 A1 (Applicant J.M. Voith GmbH) it is proposed that the fiber suspension be supplied in a transverse direction with a different set amount of retention agent and thus influence the retention rate across the web. It should be noted that in this DE application, the retention agent is specifically fed to the pulp and affects the water retention of the fiber of the self-forming pulp.

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With reference to the prior art, which is closely related to the invention, reference is made to Applicant's FI Patent 84735 which discloses a method for adjusting a lip jet thickness profile in a dual-machine twin-paper reformer, employing a twist-forming weave interposed with a two-wire web. The forming wires surround a wedge-shaped tapered forming crystal, which is fed through a lip box of a headbox into a pulp suspension jet from which the fibrous web is formed.

The cross-sectional thickness profile of the pulp suspension jet is adjusted by profiling the sheath of at least one breast roll fitted inside the forming wire in the forming ridge.

i • »· ·! : The state of the art apparently closest to the invention is apparent from Applicant's FI application 925579 (filing date 08.12.1992), which discloses. A method similar to that described in U.S. Patent No. 84735, 30, wherein a deflection compensated or adjustable breast roll is used as a breast roll in at least one of the forming wires, the inner shell of which is actively controlled to control the strain controlled by the roll. The transverse tension profile and / or the possible instability of the wire in question, particularly in the region of the forming ridge. the deflection-adjustable bobbin is intended to specifically affect the unstable-5 mouth factors in the forming region, and the deflection-compensated or adjustable bobbin cannot influence the fabric tension profile very gently, nor does the above FI application. has not addressed the effects of the tension profile in the actual twin-wire zone after forming rut in web formation and profiling.

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It is an object of the present invention to further develop the prior art described above by providing new and simple and effective means for controlling the paper web cross section profile so as to produce more uniform and quality paper across the web.

The object of the invention is to provide a new method and device which is simpler than the devices described above and which can be placed in spaces in the paper machine which are not as susceptible to water discharge and contamination as previously known for the two-wire forming strip. .

It is a non-essential additional object of the invention to provide a method and apparatus for applying a headbox lip to a transverse flow of a mass of suspension jet discharged from the lip opening resulting fiber I; : Controls orientation errors.

In order to achieve the foregoing and further objects, the method of the invention is characterized by the fact that maize * · *. said profile adjusting means or means are disposed outside the forming wire * dual wire zone, preferably in the substantially substantially free space associated with the returning of the forming wires.

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The first embodiment of the device according to the invention is essentially characterized in that the device comprises a distribution chamber which is arranged over the entire width of the forming wire or wires having a series of adjustable spray nozzles or a corresponding adjustable nozzle slot connected to the control system. which is connected by said manifold to said dispensing chamber and that the means for adjusting the transverse property profile of the forming wire or wires is arranged outside the dual wire zone, preferably in a position 10 which has a natural space for auxiliary devices.

Another embodiment of the device according to the invention is characterized in that the device comprises a tension profiling strip having a guide surface against the forming wire, said tensile profiling account combining a series of adjusting elements for controlling the transverse deflection of the tension profile 20 and that the transverse feature profile adjusting means of the forming wire or wires is arranged outside the dual wire zone at a position where there is inherent space for auxiliary devices and where such devices are not critical to at least instantaneous water and fouling.

The third embodiment of the device according to the invention is essentially characterized in that the device comprises a manifold fitted with a series of adjustable nozzles or a corresponding adjustable nozzle slot in the closure inlet between the wire and its guide roll ♦ »· s, that mentioned. From the nozzle or nozzle slit 30, a transversely profiled jet is provided which is effective on the effective wire turning beam profile and / or wire ··: transverse fluid filling profile and thus the fabric-like paper material of the wire guide roll.

35 6 110196 ί i

In a preferred embodiment of the invention, the water retention properties and / or the permeability of the wire are specifically controlled by a special regulating agent.

| For example, retention agents known per se can be used as the regulating agent, but the invention is specifically directed to the forming wire or wires. Paper fillers, finely ground fiber, and in particular substances that control the surface tension of water may also be used as regulators.

The object of the device according to the second embodiment of the invention is to adjust the tension profile of the wire in the cross machine direction. By adjusting the tension profile, the transverse property profile of the paper can be primarily influenced, or by adjusting the forming wire tension differently across different locations of the wire to produce a different dewatering impulse at different locations on the dewatering element such as a list-shoe or MB unit. In particular, the MB unit, which requires very high precision, can be simplified, especially firmer, and can handle profile corrections by wire tension profiling. The wire tension profile wire itself is not naturally smooth in the cross machine direction. The invention can also correct and compensate for profile defects already present in the fabric during the 20 manufacturing stages. Thanks to the invention, the overall tension level of the wire can even be lowered due to better control of the tension profile. This way, the tension of the wire can be optimized more easily without causing deformation in the twin-wire forming zone.

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According to the invention, the tension profiling device is mounted in the return cycle of the wire (s), i.e. where it is advantageously placed in process technology and where there is naturally more space and conditions. The tension profiling device has profiling elements • * ·. · ' and each element can be individually adjusted. Due to their different impulse, the change in the tension profile caused by the elements in the wire causes the profile to be corrected by a paper shoe, for example. The elements drag and drop each wire individually as a "loose shoe". "or the elements • · · • · * ··· '35 may push a bendable continuous strip that drags the wire and profiles its tension with the force determined by the load on the elements.

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The invention will now be described in detail with reference to certain embodiments of the invention shown in the figures of the accompanying drawings, in which details the invention is not intended to be narrowly limited.

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Figure 1 is a schematic and partially block diagram view of a first embodiment of the method and apparatus of the invention using a profiled regulator feed to a forming wire.

Figure 2 is a schematic side view of a typical and preferred application environment for the profiling system of Figure 1, namely a two-wire gritformer.

Figure 3 is a schematic side view of a first embodiment of a second embodiment of the invention.

Fig. 4 shows a transverse vertical section IV-IV in Fig. 3.

Figure 5 shows a second embodiment of a second embodiment of the invention in a manner similar to Figure 3.

... Figure 6 shows a third embodiment character of a second embodiment of the invention.

Fig. 7 shows the distribution chamber of Fig. 6 as seen from the direction A *.

Figure 8 shows preferred application positions in a two wire wireformer according to another embodiment of the invention.

30

Figure 1 schematically illustrates an apparatus arrangement according to a first embodiment of the method of the invention. The apparatus comprises a special regulating agent, such as a retention agent distribution chamber 10 known per se, which is '' ... '' arranged transversely to the former forming fabric 30 of the papermaking machine. The distribution chamber 10 is located outside the biaxial zone. 8110196 feathers or streams of a former paper machine former which have an inherently free space for additional equipment and where the equipment is not particularly susceptible to water and fouling from the web.

5, the other end of the distribution chamber 10 may be closed or provided with a control return pipe 16p. The feed pipe 16 is connected to the pressure side of the feed pump 17. The suction side of the feed pump 17 is connected to a mixing tank 18 where the regulating agent is prepared and maintained, if necessary, by suitable mixers (not shown). The feed pump 17 is controlled by the signal b from the control unit 14. By the signal b, the control fluid supply flow Fs is maintained at the set point. Control signals & x are supplied from control unit 14 via line 13. . , aN supply nozzle set 11 ^, 11N for control valves 12. Thus, the transverse distribution F (x) of the control supply in the transverse direction x of the wire 30 can be controlled. This control is effected by controlling the flow rate of the control jets S ^ -. Sn coming from the nozzles 11 ^, 11N. The control unit 14 is connected to other process automation and / or monitoring and / or setpoint units of the papermaking machine shown schematically in block 15. The unit 15 provides e.g. a setpoint Fs (x) of the control agent distribution F (x). A suitable back-up ... can be provided in the control system. The control of the control valves 12 can be carried out as such in a sensible manner, e.g. with compressed air, electricity and / or pressure fluid.

'25 Various adjusting agents and combinations thereof may be used in the profiling system of Figure 1. A preferred adjusting agent is, by itself, a known retention agent which affects the water permeability of the wire 30 and thereby the cross sectional profile of the paper web produced by the wire 30, such as the basis weight profile, the filler profile, the fiber orientation profile; 30 and / or other feature profiles. Instead of or in addition to the retention agent, fillers known per se in the paper, such as kaolin, finely ground fiber may be used. Particularly suitable are adjusting agents that can control the surface tension of water and thus the bonding forces between fibers and water. Examples of these agents include e.g.

• j »35 water soluble grease.

* 1 i 9 110196

It is essential for the selection and feeding of the regulator that it leaves the paper path fast enough and must not adversely affect the paper's quality properties and other process and environment.

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Figure 2 shows a preferred application environment for the profile control system of Figure 1, a two-wire gritformer having a lower wire 30 and an upper wire 31 delimiting the two-wire zone. The biaxial zone starts from the formation bar G between the forming and thorax rolls 33 10 and 34, into which the lip opening 32a of the headbox 32 feeds the pulp suspension jet J. This is followed by the forming roller 36, after which the upper wire 31 is separated from the web W, which moves downstream 30 to a pick-up point (not shown) for transfer to the press section of the paper machine. The body portion 100 of the forming member is schematically illustrated.

Figure 2 illustrates some typical preferred placement alternatives for the control manifold chamber 10, not all of which need to be used simultaneously. A first distribution chamber 10a is disposed within the bottom wire loop 10 and is supplied with a pro-, as shown in FIG. * filed shower Sa on inner surface of bottom wire loop before chest roll 33.

A second manifold chamber 10b is provided in connection with the lower lip beam of the headbox 32, through which a profiled regulator jet Sb ·! : on the outer surface of the lower wire 30 passing over the breast roll 33. A third regulator dispensing chamber 10c is disposed on a support beam 32b disposed in connection with the headbox 32 · upper lip beam, from which a propellant spray Sc is supplied to the outer surface 31 of the upper wire 31 passing over the forming roller 34. Above the forming roll 34, two opposed distribution chambers 10d and 10e are provided, from which the jets Sd and Se to be profiled are fed to each other on both surfaces of the upper wire 31. Instead of separate nozzles; · * 11, a single nozzle slot of width ·; · 35 can be used to be adjustable so as to provide a uniform volume-adjustable jet across the wire width instead of separate jets.

In different distribution chambers 10a to 10e different control agents may be used to provide optimum profiling. Controlling agents affect the permeability of the wires 30,31 in the twin-wire zone or other wire properties that can control the cross-sectional profile of the paper web W to achieve the above objectives.

Referring now to Figures 3-8, another embodiment of a device implementing the method of the invention will be described.

Figure 3 shows a forming wire 30 guided by guide rollers 37 and 38 in connection with its return cycle. Between rollers 37 and 38, 30 of the wire 15 is affected by a tension of the profiling strip 40, which is a set of control elements 42. The control elements affecting the frame beam 31 and the profiling strip 40 from the direction of arrow B direction.

Figure 4 illustrates the positioning and distribution of the control elements 42x ... 42N. The elements 421 ... 42 „of the adjustment-20 may be, for example, hydraulic cylinders or similar actuators. The number N of the control elements 42 is generally selected • «»: ·; in the range N = 10 ... 200, preferably N = 50 ... 100. Preferably, the adjusting elements 42 are arranged by dividing the head spindle adjusting spindles. The adjusting elements 42 adjust the deflection of the tension profiling strip 40 and • ·:, ·. 25 thereby the tension profile T (x) of the wire 30 in the transverse direction x. The adjusting elements 42 can be controlled by a similar adjusting system shown in Fig. 1 and schematically shown in block 14 in Fig. 4 only. The tension profile T (x) can influence the cross-section of the paper web formed by the wire 34 »it '·' ·. later, in more detail for 30 min.

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Figure 5 shows another way of implementing an adjustable load on the tension profiling strip 40. The profiling strip 40 is disposed between the arms 43, which at one end are pivoted by horizontal pivot shafts 44a to a plurality of 35 beams 41 and the other end by a pivoting pivot 40 by horizontal pivot 44b. Between the frame beam 41 and the profile strip 40, a series of adjusting elements 42 (N) as described above 110196 11 are arranged. This list 40 profiling affects the wire | between the guide rolls 37.38 30 to the transverse tension profile T (x), preferably by the return strain of the wire 30.

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Figure 6 shows a manifold 50 mounted on the inlet side of a wire 30 of a wire 30 with a series of adjustable feed nozzles 51, the adjustment of which can be arranged in the same manner as that of the nozzle set 11 ~ 11N. Through the distribution chamber 50, an adjustable amount of jet WAX ... WAR can be supplied to the closing gate GA between the wire guide roll 39 and the wire 30. First, this profilable jet WA can influence the distribution of the wire turning radius R (x) of the guide roll 39 by having a layer of water of varying thickness on the outer surface of the guide roll 39 at different locations. Another mode of action, which is not necessary, may be the mode of action described above with reference to Figures 1 and 2, through wire permeability and / or water fill degree profiling. Thus, in the embodiment of Figure 6, the mode of action of the first embodiment of the invention shown in Figures 1 and 2 and the second embodiment of the invention shown in Figures 3-8 can be combined.

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Figure 8 shows a two-wire forming machine in which the wire tension T (x) profiling according to the invention is applied in three different positions. In Fig. 8, the same reference numerals as in Fig. 2 are used for the respective parts. Inside the upstream loop 31, a profiling device 25 40b, such as that shown in Fig. 3, is fitted. A distribution chamber 50a, as shown in Fig. 6, and before that a profiling molding unit 40a, is arranged for the return flow of the lower wire loop 30 »'1 before the wire guide roller 39.

* »· Ί ί The transverse tension profiles T (x) of the wires 30 and / or 31 act, for example, on the curvature Rj_ of the forming shoe 35 so that the outer · '. 30 the tension pressure profile p (x) = TCx) / ^ of the upper fabric 31. Thus, by adjusting the tension profile of the wire, different dewatering pressures can be achieved at different points along the web W. Instead of a shoe 35, you can * t m> 1! MB units having a curved binary zone are used.

35 (»i» · 12 110196

The tensile profile fabric of the wires 30.31 is naturally not even in the transverse direction. With the arrangement of the invention, this profile can, if necessary, be smoothed or made in a controlled manner with a very sharp change locally. The filament tension prop-5 according to the invention can also compensate for profile defects already formed in the fabrics during their manufacture.

The claims which follow, within the scope of which the inventive idea is defined, may vary and depart from the above only by way of example.

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Claims (10)

A method of checking the transverse property profiles of a paper web produced in a web forming portion of a paper machine, wherein the method of the transverse property profile of the forming wire (30) or the wires (30,31) is controlled in the process by one or more special control means (10; 40; 50) and thereby the transverse profile is affected by the dewatering of the paper web (W), such that the intended transverse property profile of the paper web (W), as carried out by the weight, filler and / or fiber orientation profile, is characterized, said one or more control means (40a, 40b, 50a) for the profile (T (x)) being arranged outside the double wire zone of the forming wires (30, 31) most preferably in the otherwise substantially free space in connection with the return passage of the forming wires 15 (30). , 31). Method according to claim 1, characterized in that said control means (10; 50) is a feed of regulating material (S; WA), the amount and / or other characteristics of which are profiled in the transverse direction of the paper web (W), with which feeding in particular, the water permeability of the forming wire (30) or the wire (30, 31) is affected. ! A method according to claim 2, characterized in that! In the process used as a regulating agent, retention agents known per se, paper fillers, finely divided paper fibers and / or other similar substances known in connection with paper pulp, with which the surface tension properties of the water are specifically controlled or. ·: Corresponding. :: 30 Method according to claim 1, characterized in that a method (s) (40; 50) is used in the method by which to control the transverse stress profile '/ *' T (x) of the forming wire (30) or - the wires (30, 31) outside the molding * ··· 'gap area of the double-wire molds, with which profile one essentially affects the stress profile p (x) = T (x) / R of the respective wires 17 110196 (30; 31), where R is the radius of curvature of the outer wire (30; 31) having the stress profile T (x). Process according to claim 4, characterized in that the method is applied in combination with the method according to claim 2 or 3. Method according to Claim 4 or 5, characterized in that, in the method, in the gap (GA) is provided on the entrance side of the wire (30) of the wire guide roller (39) or rollers, a feeding and distribution chamber (50) for a liquid medium, most preferably the water, from which a beam or rays (WAX ... WAR) of medium, the amount of which can be controlled in the transverse direction, with which beam the effective water saturation profile of the wire and / or the curvature radius profile R ( x) of the wire (30) of the wire guide roller (39) in contact therewith. Apparatus for carrying out the method according to any of claims 1-3, characterized in that the apparatus comprises a distribution chamber (10; 10a, 10b, 10c, 10d, 10e) arranged in contact with the forming wire (30) or - the wires (30, 31) over its entire width, wherein there is a series of adjustable spray nozzles (11 ^ .. 11 ^ or, correspondingly adjustable nozzle slot, which are associated with I, "a control arrangement (14,15 ), said device comprising a feeding container (18) and a regulating supply pump (17), which pump is connected by means of a distribution pipe (16) with said distribution chamber (10; 10a, 10b). 10c, 10d, 10e) and that the control means (10; 40; 50) for the transverse (x) property profile of the forming wire (s) (30, 31) is arranged outside the double-wire zone, most preferably in such a position where the in a natural way there is room for extra '1' devices and where appropriate existing devices are not at least immediately exposed to water removed from the web (W) and to contamination in a decisive manner (Figures 1, 6 and 7). * · »· · ·· 35 Apparatus intended for use by a method according to any of the claims 4 to 7, characterized in that the apparatus comprises a stress profiling strip (40) having a guide surface against the forming surface (30). 31) and that a series of control elements (42 42 42) are joined to said stress profiling strip (40) by means of which elements the transverse (x) bend of the stress profiling strip (40) and therein through the transverse stress profile T (x) of the wire controlled by the stress profiling strip (40) can be controlled and that the control means (10; 40; 50) of the transverse (x) property profile of the forming wire (s) (30, 31) is arranged outside the double wire zone, suitable most preferably in such a position where there is naturally a space for extra devices and where the devices in question are not at least immediately exposed to water removed from the web (W) and soiled in a (Figures 3, 4 and 5). Device according to claim 7 or 8, characterized in that said devices (10; 40; 50) are arranged on the return or inlet of the forming wire (30) or the wires (30, 31). Device for carrying out a method according to any of claims 1-6, characterized in that the device includes a distribution chamber (50) arranged in the entrance gap (GA) which closes between the wire (30) and its articulated roller (31), in which chamber (50) is provided a series of adjustable nozzles (51) or the corresponding adjustable nozzle gap, that from said nozzles (51) or nozzle gap can be fed beams (WA1 ... WAR) profiled in 25 the transverse direction (x), by which the effective profile R (x) can be applied to the oscillation radius of the wire by the wire guide roller (39) and / or; the transverse (x) fluid filling profile of the wire (10) and hence the ·: transverse (x) property profile of the paper web (W) produced on this wire (30). 30 * »· · * 1 ·» l »* · · ·