JPS6149437B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a double sieve forming machine having first and second seamless circulation sieves, in a position where the sieves partially abut each other, under tension; together through a curved section that generates dehydration pressure,
and is adapted to form a convergence gap in the area approaching said curved section for receiving the paper sheet being formed and exiting separately from the outlet opening of the headbox and being introduced into a substantially adjacent position. at least two material streams, the material streams being kept separated from each other over a predetermined section by a separating member extending in the flow direction downstream of the outlet opening; The present invention relates to a method for forming multilayer paper sheets by means of a double sieve forming machine. The invention furthermore relates to a double sieve molding machine for carrying out the method according to the general concept of claim 8.

The sieve part for producing multilayer paper sheets is
There is an increasing need to be able to use materials with different properties that are distributed over the cross-section of a paper sheet. Conventionally, for this purpose, a second headbox (hereinafter also referred to as material charging device) is generally provided in the long sieve section, by means of which another sheet layer is deposited on top of the already formed preceding layer. Overlapping is done. In order to improve the bond between the layers, research is now being done to overlay as much of the subsequent layer as possible on top of the not-yet-completely-formed preceding layer.
In this case, in order to reduce equipment costs as much as possible, the flow of materials with different properties is usually carried out by one and the same charging device, and the charging device is divided according to the purpose, or if necessary, Attempts are being made to make it possible to divide the system. The use of multilayer material charging devices is generally required, especially in double sieve molding machines suitable for high speed operations, which are increasingly being used. The reason for this is that it is often not possible to use the second material device due to space constraints.

A device of the above type is described, for example, in US Pat. No. 4,141,788.
listed in the number. In the device described in this patent, the entire material flow, which is divided into three material streams by an intermediate wall in the material supply line (hereinafter also referred to as material charge line), is directly is introduced in the middle of a practically symmetrical device provided in the converging charging gap between the double sieves. Both flexible self-adjusting separating members extend between the three material streams through the outlet opening of the material charging device and into the converging gap between the sieves, so that the middle material stream is Once the dewatering position is reached, the other two material streams are in direct contact with the corresponding sieves and are dewatered by the action of the converging sieve gaps. In the other embodiment described in this publication, i.e. the embodiment in which a corresponding material charging device is used on one double sieve former with closed forming rolls, the material sheet is Since dewatering takes place only on one side (different lengths), the entire material flow goes directly into the convergence zone between the two sieves,
The overall dewatering pressure is now determined by the geometry of the interstitial area.

Similar devices in which the separating member between the material flows is prevented from protruding through the outlet of the material charging device are described, for example, in DE 2916351, US Pat. No. 3,923,593 and US Pat. No. 4,181,568. ing.

It is an object of the present invention to provide a method of the above type for forming multilayer material sheets by means of a double sieve forming machine, in which the flow of each material, i.e. the dewatering of each of the layers, is carried out under different conditions over an interval of sufficient length. The object of the present invention is to provide a method in which the flow of each material can be maintained in a separated state further forward.

Said object, according to the invention, is such that at least the flow of the first material adjacent to the first of said two sieves is unaffected by the dewatering pressure of the second sieve and of the curved section in said first sieve. ,
Pre-dehydrated to form a shaped paper sheet;
The last material stream, which is conducted through at least the last separating element and which is not delimited on the outside by the separating element, is conducted directly into the converging gap area formed by the sieve for dewatering. This is achieved by doing as follows.

In this case, the material flow impinging on the first sieve in front of the convergence gap area is subject to the static pressure of its own fluid head, if necessary, and is very slowly dewatered by this first sieve. . The preliminary dewatering section can be provided with elements for performing dewatering below the first sieve, such as a sieve table member, a suction plate or a suction box. These parts are
Preferably, the arrangement is such that a high dewatering pressure is generated in the area where each other material stream impinges on the first sieve. The reason is that the flow of each subsequent member is
This is because the water must be dewatered through the non-woven fabric already formed by the precipitation of the preceding material stream.

If the dewatering pressure caused by the sieve tension and the radius of curvature of the curved section (determined by the roll jacket) does not reach a sufficient height for the final material flow, the curvature of said curved section is It is desirable to have a larger size, and this can in fact be carried out by extending a sieve shoe with a convexly curved surface of less curvature than the roller jacket before the dewatering roll.

In order to be able to vary the dewatering section for each material stream to some extent, the position of the guide formed for each material stream by the separating member can be varied outside the material charging device outlet opening. It is desirable to do so. In order to carry out this method, it is of course important that the separating member (more on this later) has a sufficient length, which corresponds to the required impact point of each injected material. It can be determined in stages.

The paper forming method described above has an excellent possibility of directing the flow of each material adjacently for one multilayer paper seal, and it is possible to obtain and adjust the desired paper properties. As can be done, initial dewatering and direct paper formation are carried out separately. In particular, by progressively changing the sheet thickness, the difference in dewatering pressure can be increased step by step, thereby making it possible to practically combine the advantages of long sieve sections and double sieve machines. Can be combined with

According to the invention, a device suitable for carrying out the method according to the general idea of claim 8 is
In front of the point of access to the dewatering rolls, the sieve is guided over a pre-drying section, at the starting point of which at least one outlet opening of the material charging device is located, and the separating element is connected to the pre-drying section. only the flow of the first material adjacent to the first sieve at the point of origin is formed and guided so as to impinge on said first sieve, and at least said last separating element is conveyed by said separating element. It has a length such that the last material stream C is guided directly into the convergence gap between the screens.

The pre-drying section can have a curved or straight course. In the case of a linear course, at the beginning of the pre-drying section, a breast roll is arranged as is customary in order to arrange the flow of the material in a convenient manner, and the first sieve is passed around this breast roll. This leads to the preliminary dehydration section. The dewatering roll surrounded by both sieves can be a closed-faced roll, such as is used for example in the case of tissue forming, in which case the dewatering is carried out substantially in the direction opposite said rollers. It is done through a facing sieve. Said roller may also be wound with a grate-like grate thereon, and may be formed into a roll which on the side facing away from the sieve is adapted to shake off the water, or may be provided with through-holes. In this latter case, a suction box is still provided inside the roll. This embodiment can be used advantageously in the case of double sieve machines for printing paper. A grate-like grate above the roll allows air to escape laterally from the water-holding recesses, unlike blind holes.

In order to be able to vary the convergence gap between two sieves moving together, a method has already been proposed in US Pat.
As described in US Pat. No. 4,176,005, it is desirable to have adjustable guide rolls that change the direction of the second sieve in the gap area.

Since the separation elements between each material stream must be relatively long in the arrangement described above, they must be of special construction. The pre-drying section can have a length of up to 150 centimeters, in which case the last separating element generally needs to extend over this length. Conventional flexible separators, such as those described in U.S. Pat. No. 4,141,788, have the advantage of automatically adapting to material flow, but structures that are too long can vibrate or flap. be. Accordingly, in the case of the present invention, the separating member is formed as a rigid separating wall in the material charging conduit and also forms an even more rigid separating surface outside the material outlet opening. has been done. If the separation wall in the material charging line is made rigid, it is not difficult to form material charging devices for different material flows into a single unit. Rather, it is possible to combine the separating walls in unit fashion on each unit for different material flows. In addition, one material flow, preferably the last material flow,
It may also be possible to route it through separately arranged units. Since material charging systems for large flow rates often require multiple stages of diffuser rows, continuous material charging lines can be divided into separate chambers by rigid separation walls corresponding to the diffuser rows. It is easy to divide. In this way, a compact structure is obtained, so that the stage diffuser units, which were arranged in a row independently of each other, can be replaced by an integrated material charging device for multiple sheet layers in a relatively small space. It can be formed as

A common problem is when forming two or three layer sheets. When producing two-layer sheets, it is desirable to form the separating surface of a single separating wall into a rigid unit outside the exit opening, with appropriate adjustment of the injection of each material. The external boundary walls on both sides of the material charging conduit should be adjustable so as to obtain the desired results. In addition, in devices for three-layer sheets, it is sufficient to make the external boundary wall of the material charging line adjustable when two rigid separating surfaces are used. In this case, the amount of central material flow can be adjusted, as is done in many applications. However, in devices for three-layer sheets, it is advantageous to form the upper or second separating surface extending over a long distance movably, the length of which can be adjusted by means of an external actuating device. .

The movable separation surface is pivoted on the separation wall between each conduit, preferably in the area of the outlet opening of the material charging device;
In this case, the separation surface itself can be made rigid. The pivoting of the separating surface takes place slightly outside the outlet closure of the material charging device, the connection of the separating surface being such that the separating surface can be easily exchanged from outside the material charging device.

In principle, a pivotably pivoted separating surface can change its position freely during the material flow, but if the separating surface is very long, it cannot be moved by external adjustment elements. It is desirable to have one. Depending on the shape, this adjusting element can be a direct locking element, such as an adjusting spindle, which engages with the lateral end of the separating surface, but it can also be a purely locking element, such as an electromagnetic distance holder, for example, which engages with the lateral end of the separating surface. It can be made into a locking member by force. This adjusting element is preferably an electromagnetic plate integrated into the dewatering element from below the sieve and is located in the separation plane in such a way that its force is repulsive and therefore able to maintain the distance. It is made to act on a permanent magnet.

In particular, since the final flow of material must extend over a relatively long section on the separation surface, it is desirable that the upper surface of the separation surface is at least partially structured to generate small disturbances.

If the material flow and the sieve have a curved course, the separation surface, in particular of rigid construction, is adapted to the curvature.

Additional features of the invention are set out in the dependent claims.

Next, embodiments of the present invention will be described with reference to additional drawings.

The double sieve forming machine partially shown in FIG. Dehydration section 3
, and extends to a portion that partially surrounds the dewatering roll 4. From above, an outer sieve or upper sieve 6 is guided through guide rolls 5 towards a lower sieve 1 . This upper sieve also in turn extends to a part surrounding the dewatering roll 4 and is adapted to form a converging gap 7 between the upper and lower sieves in the starting area of the dewatering roll, a guide roll of the upper sieve 6. 5 is fixed to a swinging arm 8, the swinging of which causes the shape of the gap area 7 to change, ie the upper sieve 6 to be lifted from the lower sieve 1.

When referring to the first sieve and the second sieve within the scope of the present application, this difference is relevant only in which of the two sieves of the double sieve machine the preliminary dewatering of the first material fluidized bed takes place. do.
In this sense, a first sieve is defined as an upper sieve, a lower sieve, an inner sieve or an outer sieve, insofar as it is arranged such that a preliminary dewatering of the first material stream in contact with one sieve takes place on this sieve. You can do anything.

Below the linear pre-dewatering section 3 of the lower sieve 1, various dewatering elements 9 are arranged. In this case, a sieve table member or suction plate 10 is located in a first part behind the breast roll 2, and a suction box 11 is located in the part following this. Immediately before the approach of the lower sieve 1 to the dewatering roll 4, a sieve shoe 12 with a curved surface is provided. The radius of curvature of the surface of this sieve shoe 12 is larger than the radius of curvature of the dewatering roll 4. Since the dewatering pressure acting on the sheet in the curved sheet guiding area around the dewatering roll increases as the curvature of the sheet guide increases if the sieve tension is constant, connected in front of the dewatering roller in a preferred manner;
It is designed to prevent the dewatering pressure from increasing rapidly when the sieve approaches the dewatering roll 4.

In the illustrated embodiment, the sieve shoe 12 and the dewatering roll 4 are shown curved in the same direction. However, it can be provided that the sieve passes through a turning point behind the curved sieve shoe and then passes around the dewatering roll in the opposite direction of curvature.

A material charging device in the form of a multilayer material charging machine 13 is arranged in the upper front of the breast roll 2 . This material charging device can be designed, for example, as a staged differential user material charging device.
The material charging device has three openings 14, 15, 16, both of which have two outer boundary walls 17,
It is bounded by 18. The three openings are separated from each other by separation walls 19 and 20. The material charging pipes extending toward the three openings 14, 15, 16 and separated from each other and demarcated are provided with mutually independent material feeding devices 21, 22, 23.
is connected to. For example, a series of staged diffusers can be arranged between the material feed device and the material charging line, said diffuser being shown as a simple flow line 24 in the figure.

The rigidly formed separation walls 19 and 20 include
Immediately after the outlet openings 14, 15, 16 in the material charging line, separating elements 25, 26 are connected, which separating elements extend over a substantial length downstream of said outlet openings. The separation members 25 and 26 are similarly formed to be as rigid as possible, and can be set in a predetermined position by external holding and adjusting members, the details of which are not shown in the schematic diagram. .
However, it should only be made clear that the upper partition 20 is pivotally connected to the material input line so that the cross-sectional ratio of the outlet lines 15, 16 can be changed relative to each other. In order to be able to further adjust the flow of material, it is also generally provided that the boundary walls 17, 18 delimiting the outlet opening are adjustable at their ends. Due to this adjustability, the cross-sectional area of any of the three outlet openings 14, 15, 16 can be varied as required.

As can be seen from the schematic diagram in FIG. 1, the first material stream A leaving the outlet opening 14 already impinges at point 1 on the first sieve, in this case the lower sieve 1, and further on the sieve table member. , i.e. a preliminary dewatering takes place in the area of the suction plate 10. The lower separating element 25 extends further into this area, so that the second material stream B leaving the outlet opening 15 is primarily dewatered to a large extent in the suction box 11 . Before this second material stream B reaches just before the suction box 11, it is kept separated by the separating member 25 from the material stream A and the paper sheet layer already formed by this stream. The third upper material stream C leaving the outlet opening 16 impinges on the upper sieve 6 at a point. However, after passing this point, this upper material flow is kept separated from the other two material flows, namely the paper sheet layers, by an upper separation member 26 extending into the gap area 7. Only after passing the end of the separating member 26 does the next common dewatering of the layers B, C take place in the curved section of the sieve shoe 12 and the dewatering roll 4, when sheet formation from the material stream A has by this point You can see that it is completely finished.

With such an arrangement as described above, the dewatering of each material stream of a multilayer sheet can be carried out individually, which proves to be advantageous in particular when the sheet layers have different properties and different dewatering ratios.

An arrangement similar to FIG. 1 is shown in FIG. 3a. However, in this case only some dewatering elements 9 are diagrammatically shown instead of the suction plate and suction box shown in detail in FIG. It should be noted that in this embodiment, the separating members 25',
26' is introduced equidistantly into the interstitial area 7 between the sieves 1 and 6, and after the dewatering of the material stream A in the pre-dewatering section 3 has been satisfactorily completed;
Both material streams B and C are now dewatered for the first time in the interstitial region 7. Dewatering can conveniently be carried out on one side and then on both sides. This depends on how the dewatering roll 4 is formed. If this dewatering roll is designed as a closed growth roll, dewatering in the direction of the roll takes place only to the extent that the sieve mesh of the lower sieve 1 can take over. However, this dewatering roll 4 can also be a perforated roll or a roll provided with a suction box.

The separating elements 25', 26' further differ from the embodiment of FIG. 1 in that they have two sections of reduced cross-section, ie, sections 27, 28 of reduced thickness. It is. Exit opening 1
4, 15, 16, the separating members 25', 26' are still attached to the separating wall 1 in the material charging line.
9,20 and thus forms a straight continuation of the separating wall. The cross-sectional transitions of the separation members 25', 26' at points 27, 28 have a spreading effect similar to what is known as a staged differential user material charging device. Furthermore, the third b.
As is clear from FIGS. 3 and 3c, the separating elements 25', 26' are connected to each other in a hose-like manner at their outer edges. The material stream B introduced between these separating elements is therefore guided separately from the material streams A, C at the edge of the sheet.

FIG. 2 is a diagrammatic representation of the complete sieving section of a double sieve forming machine for multilayer tissue sheets. Corresponding parts are designated with the same reference numerals as in the embodiment of FIG. The first sieve is in this case the inner sieve or auxiliary sieve 6.

In this case, the two sieves 1, 6 form a seamless loop and together surround the dewatering roll 4 along a part of its circumference. The inner sieve 6 is guided by another guide roll 29,
The main sieve 1 is guided by additional guide rolls 30.

Both sieves 1 , 6 passing through the dewatering roll 4 form a substantially straight common section, which extends into the separating device 31 . The separating device has two rolls 32, 33, roll 33 can at the same time serve as a guide roll for the inner sieve 6. Both rolls 32, 33 can be physical rolls. However, as shown in the figure, roll 3
2 can also be formed as a suction roll. After leaving the separating device 31, the sieves 1, 6 are arranged to extend separately. The sieve 6 has an upwardly extending section, and a receiver 3 is placed below this section.
4 is arranged, the receiver being adapted to act as a collection device for a sieve cleaning device (not shown) arranged in this area above the sieve 6. The main sieve 1 passes from the separator 31 to the receiving device 3.
5, this receiving device consists of a guide roll 30 and a receiving roll 36. A felt 37 is placed on top of the receiving roll, which can be formed as a suction roll.
is being guided. This felt 37 is sieve 1
for receiving paper sheets (not shown) from the machine and leading them further to the drying part of the machine (not shown).

Below the dewatering roll 4 there is a receiver 38 for the water separated in the curved section of the roll. A suction box 39 is located behind this receiver 38. Below this suction box 39 another receiver 40 is arranged, which receives water smoke and other water coming from a dewatering element (not shown) additionally arranged in the area of the suction box 39. It's getting old. Finally, above the sieve 6, behind the dewatering roll 4, another receiver 41 is arranged, which receives the water spun off from the dewatering roll 4. Such a receiver arrangement is possible because both sieves are tilted downwards behind the dewatering roll 4.

A multilayer material charging device 13 is arranged above the sieve 6 and in front of the dewatering roll 4, which charging device can be constructed similarly to the embodiment of the multilayer material charging device shown in FIG. The material charging device shown in FIG. 2 has three outlet openings, which are separated from each other by two separating walls.
Separation members 25, 26 are connected directly to the walls. The lower separating member 25 reaches the dewatering roll 4 in front of the loading area of the sieves, while the upper separating member 26 extends to the interstitial area of both sieves, where the sieves surround the dewatering roll 4. It extends to In this case, the first jet material impinges on the first sieve at point 1, ie the inner sieve 6 at this time, and is pre-dewatered by means of the diagrammatically illustrated dewatering element 9. The two remaining blast materials, which are further kept separated from each other by the separating element 26, are first dewatered in the gap area of the screens 1, 6 and in the curved area of the dewatering roll 4. At the point in the figure the upper jet of material impinges on the sieve 1. Dewatering in the gap areas and curved areas preferably takes place outwards into the receiver 38 . The water sucked out through the mesh of the sieve 6 by the dewatering roll 4, which is designed as a closed forming roll, and the water that is thrown off, is collected by a receiver 41.

FIG. 4 shows an embodiment of a double sieve forming machine for two-layer sheets, in this case forming the jacket of the second or inner sieve suction roll, which roll is at the same time a dewatering roll. .
After changing direction around the breast roll 2, the lower sieve 1 passes through a relatively short linear pre-dewatering section 3.
, and then the suction roll 44 located above
and from there it is circulated again around the guide roll 30. The suction roll 44 is provided with a suction box 42 inside the suction roll 44, which is larger than half its circumference, and even after the sieve 1 is carried away from the suction roll, the paper sheet (not shown) is kept in the suction roll by the negative pressure of the suction box 42. It rests on top for further dewatering and is further processed with the help of couch rolls 45 by means of felt 43 in the area above the suction rolls 44 behind the suction box 42.

The material charging device 46 is designed as a two-layer material charging device, so that, in addition to the outer boundary wall, only one separating wall 47 is provided, the continuation of which is located outside the outlet opening. A separating element 48 is introduced into the gap area between the sieve 1 and the jacket of the suction roll 44. The downward first material stream A impinges at a point on a first sieve, in this case sieve 1, and is dewatered downwardly through this sieve 1 in a substantially straight pre-dewatering section 3. The second upper material stream B impinges on the jacket of the suction roll at a point and, over a small distance from this point, is removed by the separating element 48 from the lower material stream A, i.e. already formed by this material stream. It is kept separate from the sheet being held. The material stream B is then dewatered upwards by means of suction rolls 44 only.

A similar arrangement with a material charging device for a two-layer sheet is shown in FIG. In this case too, two sieves are used, which together surround a dewatering roll which is designed as an open dewatering roll. In this case, the preliminary dewatering section 3 of sieve 1
A dewatering element 49 is mounted below the , which additionally performs a preliminary dewatering of the downward material stream A in this area. Since the dewatering roll 50 is designed not only as a suction roll but also as an open dewatering roll, the dewatering of the upper material stream B takes place behind the end of the separating element 48 and
This is carried out outwardly through the sheet layer already formed from component stream A and through the screen 1 and inwardly through the screen 6 and the jacket of the dewatering roll 50. This double dewatering of material stream B is indicated by arrows B ₁ and B ₂ .

6 to 8 are diagrammatic representations of a double sieve forming machine which is essentially used in the production of multilayer paperboard. The lower sieve 1 essentially has the course of a conventional longitudinal sieve section and surrounds the breast roll 2, from which it passes over the sieve table elements, i.e. the upper dewatering elements in the form of suction plates 10 and suction boxes 11, 51. Then, it passes around the suction roll 52, over the sieve guide roll 30, and returns to the breast roll. Behind the suction roll 52, the paper sheet (not shown) is placed on the suction receiving roll 36.
is transferred from the sieve 1 onto the felt 37 by the sieve 1. The double sieve device consists of suction box units 11 and 51.
It is located in the area between, in which the second or upper sieve 6 from above is fitted to the lower sieve 1. Upper sieve 6 is sieve guide roll 2
Return through 9.

Behind the breast roll 2, above the lower sieve 1, a two-layer material charging device 46 is located, which includes the upper and lower boundary walls 1 of the material charging channel.
8, 17 and a separating wall 47 located between these boundary walls, which separating wall has two outlet openings 5.
3,54 are defined. The separating wall 47 of the material charging device continues in the form of a separating member 48 downstream of the outlet openings 53, 54 to separate the suction box 1.
It extends to area 1. The downward or first material stream A emerging from the outlet opening 53 is pre-dewatered, ie shaped, above the first or lower sieve 1 by the sieve table member or suction plate 10 and a part of the suction box 11. Subsequently, the second material stream B leaving the outlet opening 54 is pre-dewatered in the remaining area of the suction box 11 behind the end of the separating element 48 .

At the end of the end of the suction box group 11, in front of the double sieve device arrival area, a second material charging device 55 with a single outlet opening 56 is arranged, from which the uppermost or final material Flow C is emitted. Behind said second material device 55, the sieves 1, 6 introduced together are slightly curved and surround a dewatering device 57, which is located inside the upper sieve and can also be formed as a suction box. After the suction dewatering device 57, the sieve is curved in the opposite direction and extends over a predetermined enclosing angle to the lower sieve 1.
It passes around the dewatering-forming roll 4 located inside the dewatering-forming roll 4. This enclosing of the dewatering roll 4 is effected by a guide roller 58 located in the upper sieve 6. After this guide roll 58, the sieves curve together in opposite directions and again surround the guide roll 59 located inside the lower sieve 1, and then the upper sieve 6 returns through its guide roll 29. , and the lower sieve 1 is further guided through the suction box 51 together with a paper sheet (not shown) located above it.

In this arrangement, the curved sections (through which the two facing screens pass together) which generate the dewatering pressure can each be formed by sections with varying directions of curvature. However, in this case, in order to increase the dewatering pressure, the curvature is increased in stages. Although the surface of the dewatering device 57 is slightly curved, the jacket of the dewatering roll 4 is strongly curved. In addition, the small diameter
Therefore, the sieve guide roll 58 is strongly curved,
The amount of dehydration can be further increased by using 59.

A feature of this arrangement is that a further separating member 60 is provided, which separates at point 61 the first material charging device 4.
6 and bounded above the second material flow B. This separation member 60 runs through the entire pre-dehydration section 3 into the second
It extends to the material charging device 55 and further sieves 1 and 6.
In the area of the dewatering device 57, the third material stream C is kept separate from the already preformed sheets of material streams A, B. With this arrangement, if the dimensions of the separating member 6 and the dewatering ratio are the same, the flow of material impinging on the upper sieve 6 at a point C
is not in direct contact with the already preformed sheet layers A, B and is itself first pre-dehydrated to some extent, so that when layer C is combined with layers A, B it is in approximately the same state of dehydration. You can get the advantage of. Therefore, the already formed sheet layers A, B
can be prevented from being destroyed by the material flow C, and the dewatering can be adjusted so that further dewatering is required in the double sieve area when the sheet layers are brought together, thereby Suitable felting and bonding can occur between each sheet layer by fluid interflow without significant intermixing of the fibrous materials of the layers. This device therefore has advantages, especially for the production of cardboard, over sieving devices which only transfer fully formed and additionally pre-dewatered sheet layers to one another onto couches.

The embodiment shown in FIG. 7 is similar to that shown in FIG. 6, with the only difference that instead of the penetrating separating member 60, a separating member 60' is provided, which separates the material It is mounted on a holding member 62 which is fixed separately from the charging device 46 and which is located downstream of the outlet opening 54 of the material charging device. After the injection material B exits the outlet opening 54,
It is first moved upwardly in an unrestricted manner and subsequently enters the restricted portion between the separation members 46, 60'. Finally, in the embodiment shown in FIG. 8, a separating element 60' is provided, which initially emanates from the lower boundary wall 63 of the second material charging device 55. In this case, therefore, the material flow B extends from the first material charging device 46 to the second material charging device 55, which has an upwardly directed free surface, and in this second material charging device 55 separates the separating member 60''. The material flow C emanates from below and is kept separate from the material flow C over a predetermined section.

In particular, since the separation members 60, 60' of the embodiment shown in FIGS. 6 and 7 restrict the upper flow of the second material over a long section, disturbances occurring in the flow of the second material may occur. is small and is adapted to prevent loosening of the material in the flow section where dewatering of the material stream has not yet occurred.

Said separating member is held in its extension region by suitable means (not shown) and its position can be adjusted by suitable devices in structures where it is not completely fixed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the material charging-paper forming area of the double sieve forming machine, preferably for printing paper;
3a is an enlarged schematic diagram of the paper forming section of an apparatus similar to that shown in FIG. 1; FIGS. 3b and 3c are FIG. 3a. FIG. 4 shows another embodiment of a double sieve forming machine for multilayer sheets; FIG. 5 shows a double sieve forming machine for two layer sheets Figure 6 shows a variant embodiment of the sieve forming machine; FIG. 6 shows a double sieve forming machine for multilayer cardboard sheets, with separate material charging for the third sheet layer in the form of a second material charging device; Schematic diagram of a forming machine having an outlet opening and in which one of the separating members extends from the first material charging device to the second material charging device;
FIG. 8 is a view similar to FIG. 6, but showing a double sieve forming machine with the second separating member starting downstream of the first material charging device; FIG. 8 is a view similar to FIG. 6; FIG. 6 shows an embodiment in which the second separating member is fixed to the second material charging device. 1... Inner sieve, 4... Dehydration roll, 5...
Guide roll, 6... Outer roll, 7... Convergence gap, 9... Dewatering member, 10... Suction plate, 11...
Suction box, 13...Material charging device, 14, 15, 1
6... Outlet opening, 17, 18... Boundary wall, 19,
20... Separation wall, 25, 26... Separation member.

Claims (1)

[Claims] 1. A double sieve forming machine having first and second seamless circulation sieves, and applying dewatering pressure under tension at positions where the sieves partially contact each other. They pass together through the curved section that occurs and are adapted to form a converging gap in the vicinity of the origin of said curved section that receives the paper sheet that is being formed, and separates it from the exit opening of the headbox and leaves it adjacent to it. at least two streams of material introduced at the same time, the streams of material being kept separated from each other over a predetermined distance by a separating member extending in the flow direction downstream of the outlet opening; In the method of forming a multilayer paper sheet by means of a double sieve forming machine, at least the first of said two sieves 1 and 6 is
In a pre-dewatering region of said first sieve 1;6, which is located at a distance from said convergence gap, a first material stream A adjacent to said second sieve 6;
1 and independently of the adjacent material flows, and the last material stream C is downstream of said pre-dewatering zone for dewatering. A method characterized in that it is adapted to be guided directly into said convergence gap area 7 located therein. 2. In the method described in claim 1,
A method in which the first material stream A and the further material stream B are pre-dewatered by a first sieve 1 before finally reaching the material stream C. 3. A method according to claim 1 or 2, in which the pre-dewatering is carried out in the first sieve 1 substantially by the static and dynamic inherent pressure of the fluid head of the material stream. How to become familiar. 4. In the method according to claim 1 or 2, the preliminary dehydration in the first sieve 1
Dewatering members 9, 10 arranged on the rear side of the sieve,
11,49. 5. In the method according to any one of claims 1 to 4, the sheet already formed from at least the last material stream C and at least the first material stream A is A method in which the dehydration pressure gradually increases due to the increasing curvature of the curved section. 6. In the method according to any one of claims 1 to 5, the separation member 25, in which the material flows A, B, C are substantially fixed;
26, 48, 60 and are kept separate from each other. 7. A method according to any one of claims 1 to 6, in which each material flow A, B, C is guided through the outlet openings 14, 15, 1.
6; 53, 54; 56; 8 As a double sieve forming machine in a paper making machine,
A headbox with at least two mutually separated material guiding devices and a corresponding number of outlet openings, said outlet opening being bounded by a boundary wall extending parallel to the flow of material over the width of the headbox. a separation member located between a head box designed to allow the flow of material to flow;
a separation member adapted to keep said flow of material separated from one another for a predetermined distance downstream of said outlet opening; and first and second seamless circulation screens, together with a dewatering roll. partially surrounding and in the starting area of the dewatering roll,
In a double sieve forming machine with a circulating sieve adapted to form a converging gap for receiving the paper sheet being formed, the first sieve 1 or 6 is located in front of the origin of said dewatering roll 4; 44, 50. It extends over the pre-dehydration section 3,
At least one outlet opening 14, 53 of the head box 13, 46 is located at the starting point of the section, and the separating member 25, 26, 48, 60
is formed and guided so as to feed only the stream A of the first material adjacent to the first sieve 1 or 6 at the beginning of the pre-dewatering section to the first sieve 1 or 6, and at least the last The separating elements 26, 60 have a length such that they guide the last material stream C conveyed by them directly into the converging gap 7 between the screens 1, 6. Sieve forming machine. 9. A double sieve forming machine according to claim 8, wherein the first sieve 1 is guided from the breast roll 2 substantially in a straight line through the pre-dewatering section 3. Sieve former. 10 In the double sieve forming machine according to claim 9, a sieve table member 10 is provided below the first sieve 1 in the preliminary dewatering section 3;
Such as a suction plate 10 and/or a suction box 11,
A double sieve molding machine in which members 9, 10, and 11 for dewatering are arranged so as to gradually increase negative pressure as much as possible. 11 In the double sieve forming machine according to claim 9 or 10, a sieve shoe 12 having a convex curved surface is provided in front of the dewatering roll 4 and below the first sieve 1, and the sieve Double sieve forming machine, wherein the curvature of the sieve is smaller than the curvature of the jacket of the dewatering roll 4, and the sieve sieve is at least partly surrounded by the second sieve 6. 12. A double sieve forming machine according to claim 8, wherein the first sieve is guided around forming rolls 4 in the pre-dewatering section. 13. The double sieve molding machine according to any one of claims 8 to 12, wherein the dewatering roll 4 is a roll with a closed surface. 14. A double sieve forming machine according to any one of claims 8 to 12, wherein the dewatering roll is a roll 50 having a grid mounted on a jacket. Molding machine. 15. The double sieve molding machine according to claim 14, wherein the dewatering roller 44 additionally has a suction box 42. 16. In the double sieve forming machine according to any one of claims 8 to 15, the position of the second sieve 6 may be changed before being combined with the first sieve 1. A double sieve forming machine guided around a guide roll 5 and adapted to vary said convergence arrival gap 7. 17. In the double sieve molding machine according to any one of claims 8 to 16, the separating members 25, 26, 48, 60 are fixed between the flows of each material. The double sieve forming machine is formed as a separating surface. 18. The double sieve forming machine according to claim 17, wherein the separating surface is pivotally connected to the head box at its downstream end. 19. The double sieve molding machine according to claim 18, wherein the separation surface can be adjusted to a predetermined position by an external adjustment member. 20. The double sieve molding machine according to claim 19, wherein the adjustment member is a mechanical adjustment member that engages in shape. 21. A double sieve forming machine according to claim 19, in which the adjustment member is a force-engaged, for example, a controllable electromagnetic distance holder. 22. In the double sieve molding machine according to any one of claims 18 to 21, the separating surface, which is swingably mounted, can be replaced from outside the head box. Double sieve forming machine. 23. In the double sieve forming machine according to any one of claims 17 to 22, the separation surface may be formed into a curved shape corresponding to the guide of the sieve as necessary. Double sieve molding machine is becoming available. 24. A double sieve forming machine according to any one of claims 17 to 23, wherein the separation surface has at least partially a surface structure that generates small disturbances. Heavy sieve forming machine. 25. In the double sieve molding machine according to any one of claims 17 to 24, the outlet openings 53, 5 of the head box
4 are adjacent openings of a multilayer headbox 46, the adjacent boundary walls of which form a common separating wall 47, to which a separating member 48 is directly connected. 26 Claim 25 for two-layer sheet
In the double sieve forming machine according to paragraph 1, there is provided a single separating surface rigidly connected to a single separating wall, and both external boundary walls of said outlet openings are adjustable to vary the injection of material. Double sieve forming machine. 27 Claim 25 for three-layer sheet
In the double sieve forming machine described in Section 1, the separating wall 19 and the separating surface 25 adjacent to the first sieve 1 are formed rigidly, and the second separating surface 26 and the associated separating chamber 20
double sieve forming machine, in which the outer boundary walls 17, 18 are movably pivoted and preferably adjustable, and in which the outer boundary walls 17, 18 are adjustable. 28 Claim 25 for three-layer sheet
In the double sieve forming machine described in Section 1, both necessary separating walls 19, 20 and/or separating surfaces 2
5', 26' are formed as a tubular unit (FIGS. 3b and 3c) connected to their outer edges. 29 Claim No. 17 for three-layer sheet
In the double sieve forming machine described in any one of paragraphs 24 to 24, the final material flow C
An outlet opening 56 for the first material stream A, B is located downstream of the outlet openings 53, 54 for both first material streams A, B at a point where the sheet forming from said second material stream B has not yet been completed (FIGS. 6-8). Double sieve forming machine located. 30 In the double sieve forming machine according to claim 29, the separation member 60' that separates the second material flow B and the third material flow C separates the first material flow A and the second material flow. The double sieve machine is adapted to start at a point 62 downstream of the outlet openings 53, 54 for stream B (FIG. 7). 31. In the double sieve molding machine according to any one of claims 17 to 30, a separation member 25' adjacent to one material flow B across the same material flow. , 26' have cross-sections 27, 28 that change sharply relative to the contour forming the flow B of this material.