EP3423627A1

EP3423627A1 - Cylinder paper machine

Info

Publication number: EP3423627A1
Application number: EP17706774.1A
Authority: EP
Inventors: Hans Peter Arledter
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-02-29
Filing date: 2017-02-23
Publication date: 2019-01-09
Anticipated expiration: 2037-02-23
Also published as: AT518294A1; AT518294B1; EP3423627B1

Abstract

The invention relates to a paper machine for producing paper or paper-like material webs, wherein the device comprises a machine-wide fibrous suspension inlet (4), a trough (1) with a direct current circular screen (2) rotating therein, a trough inlet (8) and a non-woven take-off device (14). According to the invention, the trough inlet (8) has a flow-guiding device (20), wherein said flow-guiding device (20) comprises a cover (19) that covers the suspension level (A1) of the fibrous suspension and accelerates continuously the suspension stream while steering it into the trough channel inlet (9).

Description

cylinder mold machine

The invention relates to a paper machine for the production of paper or

paper-like panels, the apparatus having a machine width

Pulp suspension inlet, a trough with a rotating DC circular sieve, a trough inlet and a Vliesabnahmevorrichtung has.

Such paper machines are known, in particular for the production of

Security papers and banknotes with watermarks and / or

Security threads. However, paper machines with DC rotary sieves are still occasionally in use on older machines for the production of cardboard or paperboard. An example of such a prior art paper machine is described below. The known paper machines of this type have this disadvantage that they work without a defined headbox. In particular, there is no controlled velocity progression between the entry point of the

Pulp suspension in the trough to the point at which the screen cylinder forms a channel with the sieve tray. The course of the flow is essentially determined by the open surface of the trough.

Negative velocity gradients, that is, delays in the flow velocity, disadvantageously arise in the trough feed, although reverse flow or standing suspensions may also occur. Such areas adversely affect the flocculation state of the suspension and thus also the formation of the

formed sheet unfavorably. By the not well controlled Speed is also when introducing security threads to problems. These must be placed very precisely in the formed paper. As the flow rate increases, positionally accurate embedding of the threads in the suspension becomes increasingly problematic due to cross flows occurring. The thread can oscillate uncontrollably, which makes the placement in the formed paper less accurate. Another problem is that the fiber orientation and thus the longitudinal or transverse ratio of the sheet strength properties (eg.

Tear length, tear propagation resistance, etc.) unfavorably develop.

The aim of the present invention is to improve the flow conditions in the trough so that no negative velocity gradients, no backflows or dead zones between the flow entering the trough and the transition into the channel, formed from trough and round screen arise. Furthermore, the invention allows an adaptation of the speed at the transition into the channel independently of

geodetic level in the trough. In this way, the speed of paper production, which is in the prior art at 30-100 m / min, with the same screen cylinder diameter can be significantly increase. Furthermore, the accuracy of the positioning of security threads should be increased even at higher speeds of paper formation.

The paper machine according to the invention solves the above-described disadvantages by the features of the claims and the following description with the figures.

Hereinafter, the prior art and the invention will be described with reference to the drawings.

Fig. 1 shows schematically a section through a paper machine according to the prior art.

Fig. 2 shows schematically the section through a first embodiment according to the invention and

Fig. 2a shows a modified embodiment.

Fig. 3 shows in partial section a detail.

Fig. 4 shows a plan view of this detail. Fig. 5 shows a third embodiment.

Fig. 6 shows another embodiment with associated control scheme and Fig. 7 shows an embodiment with adjustable overflow bar.

Fig. 1 shows a paper machine according to the prior art. The paper machine essentially comprises a trough 1 with a round screen 2 running therein with the direction of rotation 3. Via a pulp suspension inlet 4, the suspension, which consists essentially of water, paper fibers and various additives, via the cross-flow distributor 5, a turbo liner 6 and the inlet nozzle 7 out in the trough inlet 8 and passes from there via the trough channel inlet 9 in

Flow direction 10 in the channel 1 1, which is formed between the round screen 2 and the trough 1. The cross-sectional ratio between trough channel inlet 9 and

Trough channel outlet 12 can be changed by adjusting the position of the Rundsiebachse 13. The direction of rotation 3 of the round screen 2 and the flow direction 10 of the pulp suspension is rectified.

By constant inflow of the suspension is formed in the trough inlet 8 of

Suspension mirror A1, while inside the round screen 2, the suspension mirror A2 prevails. The difference in pressure caused by the difference in height causes the flow of the liquid constituent of the suspension into the interior of the round screen and the corresponding deposition of a fibrous web on the surface of the round screen. The nonwoven fabric is from a nonwoven removal device 14th

removed, which here consists of a couch roll 15 and a decrease fleece 16. By Abnahmevlies 16 the fibrous web is removed from the round screen and fed to further processing.

The couch roll 15 is preceded in this embodiment, a so-called Egoutteur 17, which serves to equalize the leaf formation. By embossing or other watermark inserts on the round screen 2 watermarks can be provided.

Residual suspension, which flows over the trough channel outlet 12, can be withdrawn via the outlet 18 and recycled. It should be noted that the suspension mirror A1 in the trough inlet 8 in its altitude by the diameter of the round screen 2 and the position of the couch roll 15th

is limited. Therefore, the differential pressure between A1 and A2 can not be increased arbitrarily. This limits the speed of the paper machine.

In the pulp suspension feed 4, the velocity profiles are on

various points drawn. While at the beginning of the turbulence insert 6, a relatively homogeneous flow is observed, the flow path in the direction of the round screen 2 is inhomogeneous and takes a negative course. This leads to the aforementioned difficulties.

It should again be emphasized that the illustration of this prior art is only an example and many modifications are possible. With all these

But paper machines is uniformly the problem exists that the trough inlet 8 has a free suspension mirror by the round screen 2 rotates.

Fig. 2 shows a simplified example of a paper machine according to the invention, wherein like reference numerals have the same meaning. There are only the machine parts essential for the present invention shown, so that the devices such as couch roll 15, Vliesabnahmevorrichtung 14 and Egoutteur 17 are not shown, but can be arranged the same as in Fig. 1.

According to the invention, the trough inlet 8 has a flow-guiding device 20. This comprises a fluid level covering and the suspension flow

continuously accelerating in the trough channel inlet 9 guiding cover 19. The cover 19 comprises a rigid upper lip 21 bent downwards at the end, and subsequently a flexible skirt 22, which is arranged or can be arranged adjacent to the round screen 2. This flow guide extends over the entire length of the round screen 2, as far as it is acted upon by the pulp suspension and is sealed to the end wall of the trough. The angular position of the cover 19 to the inflow into the channel 1 1 is adjustable and changeable by a hinge 23. Furthermore, the position of the skirt 22 on the upper lip 21 is adjustable by a locking device 24. By this adjustment, the pulp suspension feed 4 to the other

Be adapted circumstances such. B. to changed diameter of the

Round screen. Furthermore, the upper lip 21 with its pivot joint 23 at a

Moving plate 25 attached, which is displaceable and attached to the tray inlet to adjust the distance to the round screen 2 can. With the displaceability of the skirt 22 relative to the upper lip 21, it is also possible to adjust the apron protrusion.

The apron is attracted by the round screen by the pressure difference between the pressure inside the round screen 2 and the pressure in the tray inlet 9, whereby the sealing effect is created. Due to the lateral sealing of the upper lip 21 and the skirt 22 to the side trough wall is, by from the upper lip 21 (with skirt 22) and cylinder molds formed Rundsieb-apron gusset 41, no

Fibrous suspension. There is thus no suspension mirror A1 in this gusset. A1 is shown in dashed lines in FIG. 2 as a theoretical level.

This theoretical level corresponds to the pressure generated by the feed pump in the inlet channel (nozzle). As the pressure in the nozzle increases, so does the pressure

theoretical level (also over the Trogrand).

In order to increase the area by the skirt 22 abuts the cylinder mold, without affecting the flow conditions in the nozzle channel negative, it may be necessary, the shape of the upper contour of the upper lip 21 and the

Attachment point of the skirt 22 to be designed so that the outlet tangent of the skirt 22 comes to lie on the cylinder mold at a desired point above the rigid end point of the upper lip 21. This can be done by a attached to the upper lip 21 contour body 42, as shown in Fig. 2a. The contoured body 42 may be interchangeable to provide different contours. The upper contour of the upper lip 21 ensures that, despite the laying of the attachment point (locking device 24), a sufficient gusset is formed. This gusset is required for the introduction of so-called window threads.

Window threads are only incompletely covered and embedded by fibers on the side facing the sieve. The thread is partially covered by fibers on this side. To achieve this, the thread is already in front of the first one

Dewatering point of the round cylinder brought to the screen. Of the

Point of support of the thread is therefore in the gusset in front of the window threads

Support point of the apron 22. The thread is only partially washed by the suspension.

Such a variant with guided on the upper lip top apron 22 and

Thread guide 26 is shown in detail in the figure of Fig. 2a.

In Fig. 2 and Fig. 2a is also the arrangement of a guide tube 26th

located, which serves a thread z. B. a metallized

Embed plastic security thread in the fibrous web to be formed. The arrangement of the guide tube or a juxtaposed series of such guide tubes will be described with reference to FIG. 3.

3 and 4 show this arrangement of the guide tube 26, which is fastened in this embodiment, for example only in a ball joint 27, whereby the position of the guide tube 26 is adjustable. The ball joint 27 is mounted in a sealing plate 28 which is displaceable in the horizontal direction to allow the lateral adjustment (transverse to the web) of the position of the guide tube 26.

Depending on the size of the paper products to be formed, for example depending on

Banknote size, for example, every 15 cm, such a guide tube 26 are attached to the upper lip 21. The guide tubes 26 can also be oscillated via an external drive, if such an offset of the securing thread of ± 2 mm to ± 15 mm in the paper web is desired. In Fig. 3, the pivot joint 23 and the displacement plate 25 is still shown, which is fastened on a machine-fixed construction element 29 in a corresponding displacement position.

Fig. 5 shows a further embodiment in which in the trough inlet 8 and the cover 19 upstream of a suspension storage box 30 is arranged. By arranging this suspension box 30, the hydrostatic pressure, which corresponds to the dewatering pressure through the screen, can be increased, which is formed by the difference to the suspension level A3 in the suspension stowage box 30 and the suspension mirror A2 set in the interior of the round screen. The suspension stowage box 30 is up to form an air cushion 31

where appropriate, to control the pressure and the

Suspension level a supply and discharge 32 may be provided. With

Reference numeral, the foam overflow 40, an overflow is drawn to

To be able to derive excess suspension or formed foam.

This type of pressure-vacuum control can often be found in headboxes of the paper industry. About the air cushion pressure, the level A3 is kept constant. High air cushion pressure therefore corresponds to a higher level of stagnation than A3 and low pressure (vacuum) corresponds to a lower level. The stagnation level thus corresponds to the pressure in the inlet channel (nozzle). In this way, a "feed level" is realized, which can be arbitrarily set in contrast to an open trough namely also above the theoretical level A1 or below this.

A regulation is shown in Figure 6.

In the example Figure 5, the level is generated solely by the pump pressure. The lowest possible "level" corresponds to the highest point of the upper lip.

As a detail, it should be noted that the pulp suspension feed from the crossflow distributor 5 is guided via a perforated plate 33 into a settling chamber 34. Furthermore, the pulp suspension flows through a turbulence insert 6, so that the most uniform flow profile is generated in the trough channel inlet 9 a to achieve balanced velocity profile and pulp concentration over the entire cross section.

In Fig. 6, the scheme of another embodiment variant with associated control and line devices is shown. The pulp suspension passes through the cross-flow distributor 5 through a first turbulence insert 34 in the suspension stowage box 30, and a second turbulence insert 35 in the trough inlet 8. The pressure in the air cushion 31 can be controlled via an air pressure source 36 and associated control valves 37. Furthermore, there is a control bypass 38 which cooperates with the white water tank and the foam overflow 40 for the feed quantity of the pulp suspension.

Fig. 7 shows schematically the view in the direction of the round screen axis 13. The same design features are provided with the same reference numerals as in the preceding figures. As in the previous embodiments, the round screen 2 is adjustable in its position within the trough 1, whereby the geometry of the flow channel is adjustable. The trough 1 has at the outlet 18 a

Suspension level A4 in the course of determining or largely influencing overflow strip 44. The position of the overflow strip 44 is adjustable both in height, as well as in their distance from the round screen 2.

This adjustability of the overflow allows or facilitates on the one hand the removal and installation of the round screen in the trough and on the other hand determines the position of the overflow strip 44, the suspension mirror A4 and thus the pressure ratio in the round screen. The adjustment is made by the adjusting member 47 and the pivot 46. The height of the position of the overflow strip is made by moving according to arrow 48th

The smaller and higher the overflow gap at the outlet and thus at the overflow strip 44, the higher the dewatering pressure at the round screen. For example, the distance between the round screen and Überlauleiste between 2 mm and 60 mm are, this information is only an example. In Fig. 7 it can also be seen that the trough 1 is reinforced by ribs 45 to the trough

1 sufficiently rigid. Both the trough 1, as well as the rotatable round screen

2 are interchangeable.

In the suspension flow inlet here is also an air-pressure-controlled arrangement with a suspension storage box 30 is provided, the air cushion pressure can be controlled by the supply and discharge line 32 for air.

The displacement plate 25 has to adjust the position of the upper lip 21 with your skirt 22 on a sliding gear 43, whereby the position of the upper lip 21 and skirt 22 can be adjusted or changed.

It should also be noted with regard to the guide tube 26 that this can be connected to a water or air pressure device in order to be able to shoot the thread down to the round screen at the beginning of the papermaking process.

In the arrangement shown in Figure 7 it should be noted that the inlet channel with the upper lip 21 and the overflow strip 44 are arranged on the screen cylinder such that the proportion of the screen cylinder has direct atmospheric contact is less than 30 degrees. The direct contact of the screen to the atmosphere is limited by the skirt 22, the fiber suspension in the trough and the fibrous web formed until it is removed by the couch roll 15. This arrangement allows the

Drainage performance of the screen cylinder by a blower suction or

Fan further increase.

Figures 2 to 7 each show modified structural elements, the arrangement of which is not limited to the specific illustrations in the figures, but the features and construction details in all embodiments may be provided or omitted.

For understanding the invention, the following is still to be considered. In such paper machines, the longitudinal or transverse ratio and the fiber orientation are further important paper properties. The longitudinal or

Transverse ratio and fiber orientation are exclusively determined by the

Flow rate determined in the transition region and the geometry of the channel formed from trough wall and screen cylinder.

This speed profile and thus the fiber orientation and the longitudinal or transverse ratio of the strength properties of the paper are dependent on four

factors:

1 . the feed rate to the round screen,

2. the stowage target in the trough,

3. the inlet cross-section and

4. the geometry of the channel formed by trough wall and screen cylinder.

For given round cylinder and tub is the trough wall and

Strainer resulting channel set so that it tapers from start to finish, according to the drainage rate of the screen, continuously. By the horizontal displacement of the screen cylinder, the inlet cross section is changed in the channel, but also the tapered channel. This is therefore only minor

Scope allowed.

Since the inlet takes place in the prior art in an open trough, that must

Stagnation level coincide approximately with the upper edge of the inlet cross-section. If the level is significantly above this point, there is an unfavorable delay of the pulp suspension when entering the trough. If the suspension level is below, there is also inadmissible turbulence.

The determination of the water level (top edge) given the cylinder diameter are constructive narrow limits. These limits result from the

Position of the dandy cutter and the squeeze roller wrapped around the felt. These rollers must be above the suspension level. In addition, the suspension wetted circumference of the cylinder should represent a maximum. Furthermore, the water level is influenced by the height of the overflow edge at the outlet. In practice, the inflow at the given stowage level in the trough is dependent on:

the position of the outlet side overflow edge,

the drainage resistance at the round cylinder (depending on consistency and mesh size) and

the flow resistance in the channel formed between trough and screen cylinder.

It is state of the art today, the fiber orientation and thus the longitudinal or

Transverse ratio of the strength properties of the paper and the formation of the sheet on the feed rate and the displacement of the screen cylinder to influence. However, due to the relationships shown, this is only possible and expedient to a very limited extent. The limited influence of the open system on these sheet properties represents a significant disadvantage of the DC Rundsiebs.

The described invention is firstly based on the problem that

To improve flow conditions in the trough so that no negative

Velocity gradients, backflows or dead zones occur.

This is ensured by a flexible upper lip with a flexible apron. The upper lip is sealed to the lateral trough wall. In the nozzle area has the

Upper lip over a flexible apron, which serves as a seal to the cylinder. The

Apron is variable in length. It can either be directly connected to the end of the upper lip or mounted anywhere on the lip top and hanging it over the lip end. The upper lip is horizontally and vertically adjustable to ensure an optimal nozzle geometry, depending on the cylinder diameter. For this purpose, the lip has a swivel joint on the inlet side with a horizontal adjustment and optimally a vertical adjustment. The cylinder is horizontally displaceable in the trough as in the prior art.

In order to ensure the threading of security paper and banknote paper, the upper lip has a guide tube passage. Each guide tube is individually adjustable to ensure the desired position in the paper. In addition, the guide tube has in the sealed

Feed through a ball joint, which allows charging during operation.

The invention is also based on the problem that the speed on

Transition into the channel with open DC round sieve can not be influenced independently of the geodetic level of the suspension. In addition to the criterion that the flow from the inlet to the nozzle to the transition into the channel should have an undisturbed and continuously accelerated flow profile, it is also crucial to keep the velocity in the channel approximately in a constant relationship to the speed.

This is done by the approach described below. The

The velocity of the jet at the nozzle end can be determined according to the following formula: v ² = 2 gh / fv = jet velocity in m / sec

g = gravitational acceleration m / sec ²

h = damming height m

f = apron factor (empirical)

For this purpose, there are two approaches to the closed design of the DC rotary filter, which are used depending on the speed range traveled.

1 . The discharge speed is determined by a speed-controlled pump; So she works hydraulically.

2. The suspension level above the nozzle end is level-controlled and has the same height at all speeds. The discharge speed and the associated damming height are achieved by an air cushion and automatically controlled. At slow speeds, when the fixed suspension level exceeds the required damming height, the air cushion is also automatically controlled in the vacuum area. This allows the headbox also at

Run speeds from 30 m / min and to well over 150 m / min. A suitable pressure and vacuum control with a corresponding

Headbox is shown in Fig. 6.

LIST OF REFERENCE NUMBERS

(1) trough (28) sealing plate

(2) Round sieve (29) construction element

(3) Direction of rotation (30) Suspension storage box

(4) pulp suspension feed (31) air cushion

(5) Crossflow distributor (32) Inlet and outlet

(6) Turbulence insert (33) Perforated plate

(7) Inlet nozzle (34) First turbulence insert

(8) Trough inlet (35) Second turbulence insert

(9) Trough duct inlet (36) Air pressure source

(10) flow direction (37) control valves

(1 1) Channel (38) Control bypass

(12) Trough drain (39) White water tank

(13) Round sieve axis (40) Foam overflow

(14) Fleece Picking Device (41) Round Screen Apron Gusset

(15) Gautschwalze (42) Contour body

(16) Removal fleece (43) Shifting gear

(17) Egoutteur (44) Overflow bar

(18) Drain (45) Ribs

(19) Cover (46) Swivel

(20) Flow guiding device (47) adjusting member

(21) upper lip (48) arrow

(22) apron

(23) Swivel joint (A1) Suspension mirror

(24) Locking device (A2) Suspension mirror

(25) Sliding plate (A3) Suspension mirror

(26) Guide tube (A4) Suspension mirror

(27) Ball joint

Claims

claims

1 . A paper machine for making paper or paper-like panels, said apparatus comprising a machine-pulp pulp suspension feed (4), a trough (1) having a DC rotary sieve (2) rotating therein, a trough infeed (8) and a web take-off device (14), said trough infeed (8) has a flow guiding device (20), characterized in that the

Flow guiding device (20) a the suspension mirror (A1) of the

Having fibrous suspension covering and the suspension flow continuously accelerating in the trough channel inlet (9) directing cover (19).

2. Paper machine according to claim 1, characterized in that the cover (19) seen in the flow direction, a rigid bent at the end downwards

Upper lip (21) and then a flexible skirt (22), which can be arranged adjacent to the round screen (2).

3. Paper machine according to one of claims 1 or 2, characterized in that the cover (19) at the top has a contoured body which determines the upper bearing point of the flexible skirt on the round screen to a designated point with defined gusset (41), without the Flow channel too

influence.

4. Paper machine according to one of claims 1 to 3, characterized in that the angular position of the cover (19) to the inflow direction (10) in

Trough channel inlet (9) by a hinge (23) is adjustable and changeable.

5. Paper machine according to one of claims 1 to 4, characterized in that the nozzle cross section of the flow-guiding device (20) before the inlet into the trough channel inlet (9) through the rotary joint (23) is adjustable and variable.

6. Paper machine according to one of claims 1 to 5, characterized in that the position of the flow guide (20) in the trough channel inlet (9) for adaptation to different Rundsiebdurchmesser by the rotary joint (23) of the cover (19) is adjustable and variable.

7. Paper machine according to one of claims 2 to 6, characterized in that the upper lip (21) is fastened with its rotary joint (23) on a sliding plate (25) which is displaceable and attachable to the trough inlet to the distance to the round screen (2 ).

8. Paper machine according to one of claims 2 to 7, characterized in that the skirt (22) relative to the upper lip (21) is displaceable in order to adjust the apron projection.

9. Paper machine according to one of claims 2 to 8, characterized in that the upper lip (21) has an opening for receiving one or more

Guiding tubes (26) for embedding threads, preferably security threads, in which fibrous web formed on the round screen has.

10. Paper machine according to claim 9, characterized in that the

Guide tube (26) in a joint body, preferably a ball joint (27) is arranged, which is mounted in a sealing plate (28) which in a

Recess of the upper lip is sealingly displaceable.

1 1. Paper machine according to one of claims 1 to 10, characterized in that the trough inlet (8) is preceded by a suspension storage box (30) through which a hydrostatic pressure is buildable, which is higher than the maximum pressure by the on the round screen (2 ) achievable maximum level of pulp suspension.

12. Paper machine according to one of claims 1 to 1 1, characterized in that the trough (1) on (drain (18) has a suspension mirror (A4) in the outflow determining overflow strip (44) whose position in height and

Distance to the round screen is adjustable.