FI127630B

FI127630B - Forming section of a fiber web machine and a secondary forming unit for a multiply forming section of a fiber web machine

Info

Publication number: FI127630B
Application number: FI20146106A
Authority: FI
Inventors: Sami Anttilainen; Juan Cecchini; Antti Poikolainen
Original assignee: Valmet Technologies Inc
Priority date: 2014-12-17
Filing date: 2014-12-17
Publication date: 2018-10-31
Also published as: FI20146106A; DE102015121642A1; CN105714591A; AT516646A2; AT516646B1; CN105714591B; AT516646A3

Abstract

The invention relates to a forming section of a fiber web machine, said forming section (10) including a plurality of forming units (24, 34, 44, 54), including a first forming unit (24) for forming at least first web layer (12, 13) and having at least one wire (16), at least one secondary forming unit (34) for forming a second web layer (15), which secondary forming unit includes a headbox (35) including a slice opening (21), a top wire (36) running in a loop having a run (47) cooperating with the wire of the first forming unit, and a lower guide roll (59) followed by dewatering means (50) located in the loop of the top wire, and in which the headbox of at least one secondary forming unit is arranged to supply the stock to the surface (S) of the top wire after the lower guide roll. The slice opening of the headbox is arranged to locate between an area (45) of the lower guide roll and the wire of the first forming unit. In addition, the invention relates also to a secondary forming unit for a multiply forming section of a fiber web machine.

Description

FORMING SECTION OF A FIBER WEB MACHINE AND A SECONDARY FORMING UNIT FOR A MULTIPLY FORMING SECTION OF A FIBER WEB MACHINE

The invention relates to a forming section of a fiber web machine, said forming section including a plurality of forming units, including - a first forming unit for forming at least first web layer and having at least one wire, - at least one secondary forming unit for forming a second web layer, which secondary forming unit includes - a headbox including a slice opening, a top wire running in a loop having a run cooperating with the wire of the first forming unit, and a lower guide roll followed by dewatering means located in the loop of the top wire.

In addition, the invention also relates to a secondary forming unit for a multiply forming section of a fiber web machine.

In a so called forming section of a fiber web machine water is removed from the fiber suspension spread on the wire for forming a web. The forming section is also called a wire section. The forming section is provided with several dewatering means in succession, generally located behind the wire .

The development is towards increasingly high demands on paperboard products manufactured. This applies both to the demand on mechanical properties and also to the ability of the material to produce a good printing result. New regulations for recovery increase demands for use of recycled fibres to a greater extent. This implies that ever poor fibres shall be used to paperboard products with ever high demands for quality and runnability. A vast number of methods and machines for manufacturing paperboard are described in the literature and have been used in practice with greater or lesser success. PCT-patent application publication WO 97/45589 can be presented as one example of these. This discloses a solution including a primary forming unit supplying stock on top of the fourdrinier wire followed by several secondary forming units each of which supplying the stock on top of the layer previously formed on the fourdrinier wire. The stock supplied by the secondary formers has quite low consistencies.

Common to the methods and machines is that they cannot easily fulfil the requirements mentioned above, particularly in the case of manufacturing folding boxboard which is composed of a top layer, an underliner, a bulky core and a back layer, where it is particularly important for the core to have the best possible properties, such as formation, bulk and basis weight profile, and for the underliner to have such uniformity that the top layer formed thereon will have the best possible printability. In addition, the layered web formed in the previously stages on top of the fourdrinier wire is not yet very firm and when combined to the low consistencies of the secondary forming units this may causes problems in terms of runnability because the secondary layers are not very well infiltrated. In addition, this seriously limits the running speed of the machine.

An object of this invention is to provide a forming section of a fiber web machine and a secondary forming unit for a multiply forming section of a fiber web machine providing good controllability for adjusting bonding consistency and, in addition, forming in capacity point of view good consistency profile to the bottom side of the web. The characteristic features of the forming section according to the invention are set forth in Claim 1 and the secondary forming unit in Claim 9.

In the invention a slice opening of the headbox is arranged to locate between the area of the lower guide roll and the first forming unit. This provides a prefiltration of the layer and improves the converging ability of the layer to the other layers formed already previously. This also allows the use of the lower consistencies in connection with the secondary forming units i.e. greater flows. Owing to this the quality of the web is improved.

Board machine rebuilds are easy to make with the solution according to the invention. In addition, secondary forming unit space requirement is much lower than in the state of the art solutions .

In addition, the forming process for the layers provides considerable improvement with regard to formation, surface structure and bulk. The separate supplying of the stock in secondary forming units causes also cutting forces to the stock. This improves the formation. Owing to this the final web will be thick and firm and it does not glow through the core layer. In addition, the plurality of layers makes dewatering easier. Other additional advantages achieved with the invention become apparent from the description, and the characteristics are set forth in the claims.

The invention, which is not limited to the embodiments set forth below, is described in more detail by making reference to the appended drawings, in which

Figure 1 shows a lateral view of a forming section of a fiber web machine according to the first embodiment of the invention with hybrid former and one secondary forming unit for manufacturing a three-layer paperboard web,

Figure 2 shows a lateral view of a lower portion of a secondary forming unit according to the first embodiment of the invention,

Figure 3 shows a lateral view of a lower portion of a secondary forming unit according to the second embodiment of the invention, and

Figure 4 shows a lateral view of a forming section of a board machine according to the second embodiment of the invention with hybrid former and three secondary forming units for manufacturing a four-layer paperboard web.

Figure 1 shows schematically an exemplifying embodiment of a wet end i.e. a forming section 10 in a fiber web machine for manufacturing a paperboard web 11. In this embodiment the web 11 is composed of three layers - a back layer 12, a core 13, and a surface or top layer 15. In the embodiment the forming section 10 includes now an extended hybrid former 27 having at least one wire 16 running now in a loop around an upstream breast roll 17, a downstream suction couch roll 18, a wire running roll 19 and a plurality of guide rolls 20 including alignment and tension rolls 22, respectively, the stock-dewatering and web-forming upper run 23 of the wire 16 of the first forming unit 24 between the breast roll 17 and suction couch roll 18 being mainly horizontal. After the forming section 10, the web 11 is led to a press section (not shown).

The forming section 10 includes a plurality of forming units 24, 34 for forming the layers 12, 13, 15. In the embodiment shown a first forming unit 24 includes at least one wire 16 and a headbox 25 arranged near the breast roll 17 to supply jets of stock on the upper run 23 of the wire 16 of the first forming unit 24, said stocks having consistencies of 0.5 - 1,0%. In this embodiment the headbox 25 is a so called multi-layer headbox that may be known as such, for example.

The first forming unit 24 shown in Figures 1 and 4 includes also a so called top wire 42 i.e. hybrid forming unit 43. In that the water is removed upwards as well by dewatering means 4 6 .

The hybrid former 27 has a first forming unit 24 including a forming table 26 including dewatering means (not shown) following the breast roll 17. In addition, inside the loop of the wire 16 of the first forming unit 24 and lower side of the upper flat run 23 of that there are several other dewatering and/or runnability devices 32, 33, 37 that may be known as such. Their positioning will be described in detail later. Some examples of the dewatering means are hydrofoils or suction members such as suction boxes. The forming table 26 is arranged in the beginning of a forming section of the hybrid former 27, on the lower side of the upper run 23 of the wire 16 of the first forming unit 24, in order to dewater the stock, thereby producing at least first web layer 12, 13, designated now back and core layer, having a consistency of about 6 - 15%, preferably 8 - 12%, for example.

In addition to the first forming unit 24 the forming section 10 includes also at least one secondary forming unit 34 for forming a second web layer 15. The secondary forming unit 34 is after the hybrid forming unit 43. Now the secondary forming unit 34 is for forming a third layer 15, designated top layer, in cooperation with the upper run 23 of the wire 16 of the first forming unit 24 within a second section B of the hybrid former 27.

The secondary forming unit 34 includes a headbox 35, a top wire 36 running in a loop and dewatering means 50. Downstream of the headbox 35 is a support table 37 for the wire 16 of the first forming unit 24. The top wire 36 runs over a plurality of guide rolls 38, 59 and in an accompanying run 47 (Figures 2 and 3) within at least part of said section B for cooperation with the upper run 23 of the wire 16 of the first forming unit 24. In the bottom of the run of the top wire 36 there is a lower guide roll 59 followed by dewatering means 50. By means of the guide roll 59 the running direction of the top wire has been changed towards the dewatering means 50. In the described embodiments the lower guide roll 59 is arranged close to the upper run 23 of the wire 16 of the hybrid former 27 and the headbox 35. The dewatering means 50 are located in the loop of the top wire 36. In addition, the dewatering means 50 are followed immediately after the guide roll 59.

The headbox 35 of the second forming unit 34 is designed to emit a jet of stock in order to form the top layer 15 on the previously formed back and core layers 12, 13 carried by the wire 16 of the first forming unit 24. As shown in Figures 2 and 3, according to the embodiments, the headbox 35 of at least one secondary forming unit 34 is arranged relative to the top wire 36 and the lower guide roll 59 in such a way that it is arranged to supply the stock to the surface S of the top wire 36 of the forming unit 34 after the lower guide roll 59. Advantageously the slice jet of the headbox 35 hits to the surface S of the top wire 36 on the area of the dewatering means 50.

In addition, the slice opening 21 of the headbox 35 is arranged to locate between the area of the lower guide roll 59 and the wire 16 of the first forming unit 24. In the embodiment the slice opening 21 of the headbox 35 is arranged to locate between the middle point of the lower guide roll 59 and the wire 16 of the first forming unit 24. Owing to this the stock of the secondary forming unit 34 has been supplied to the own wire section including dewatering means 50 before combining the web layers 12, 13, 15. Owing to this the headbox 35 of the secondary forming unit 34 is separate from the primary web running on the wire 16. This improves the pre-filtration of the layer 15. In addition, this also gives more space to the headbox structures between the slice channel 39 and already formed web 12, 13 and makes possible to improve the running speed of the board machine.

The jet angle of the headbox 35 may be very low, for example, 1 - 3°. The jet from the slice opening 21 of the headbox 35 is mainly parallel with the web-layers 12, 13 being on the wire 16 of the first forming unit 24. The impact angle of the stock supplied from the headbox 35 of the at least one secondary forming unit 34 to the top wire 36 may be, for example, within the interval 0,1 - 5°. The rotation of the guide roll 59 causes a vacuum which adheres the jet in contact with the top wire 36. In addition, the dewatering means 50 of at least one secondary forming unit 34 may be at least partly non-pulsating type. This assists that the layer 15 has been caught to the top wire 36.

The consistency of the stock supplied by the headbox 35 of the secondary forming unit 34 and forming the second layer 15 may be, for example, within the interval 0,3 - 1,5% and the basis weight, for example, 20 - 80 g/m2. The dewatering means 50 of the second forming unit 34 dewater the stock so that after that the layer 15 formed by the secondary forming unit 34 has a consistency of 5 - 12% and the combined three-layer web 12, 13, 15 formed has a consistency of 6 - 15%, preferably 8 - 12%, for example .

In the described embodiments the dewatering means 50 of the secondary forming unit 34 include an upper table 69 arranged on the lower side of a housing 71. The housing 71 is arranged inside the loop and the upper table 69 at the beginning of the lower run of the top wire 36 opposite to the upper flat run 23 of the wire 16 of the first forming unit 24. The housing 71 includes in both embodiments three successive suction chambers or boxes 74 - 76. The amount of suctions may rise in the running direction of the top wire 36. As well as the upper dewatering table 69 the chambers 74 - 76 are located in the loop of the top wire 36 directly after the lower guide roll 59 of the secondary forming unit 34 and on the upper side of the lower flat run of the top wire 36, in order to dewater the stock, thereby forming said layer 15 formed of the secondary forming unit 34 with a consistency of 5 - 15%, preferably 7 -12%.

The upper dewatering table 69 may define a plane, supporting to which the top wire 36 and the layer 15 run in sliding contact with the table 69. The dewatering means 50 may be suspended via adjustment means (not shown) enabling the upstream and downstream ends of the dewatering means 50 to be raised and lowered independently of each other in order to incline the dewatering means 50 in relation to a reference plane at a tangent to the lower guide roll 59.

In the disclosed embodiment the housing 71 includes three successive suction chambers 74 - 76 to collect the white water pressed up through the top wire 36 due to the suction action.

In the embodiment of Figure 2 the first chamber 74 and in the embodiment of Figure 3 the first and the second chamber 74, 75 act to the layer 15 via sections 28 having a plurality of holes 29. The corresponding construction may also be implemented by means of narrow elongated slats or laths fixed to the housing and separated by spaces being for example 5-15 mm. These dewatering foils are in contact with the top wire 36 and a gap is created between successive dewatering laths which width may be 5 - 10 mm, for example. In this the layer 15 is subjected to non-pulsating removal of water.

The holes 29 may be bored and arranged to the corresponding sections 28 of the upper table 69 that is arranged on the lower side of a housing 71 including the suction chambers 74 - 76. In both embodiments at the beginning of the first chamber 74 before the section with the holes 29 is arranged an elongated continuous slit 40. The slit 40 is arranged to provide a passage to upwards for the air flow appearing immediately after the lower guide roll 59 in the closing gap.

In addition, in the both described embodiments the upper dewatering table 69 includes one or more sections 41 having a plurality of elongated slats or laths 79, i.e. blades, fixed in relation to the housing 71 and separated by spaces 78. These dewatering foils are in contact with the top wire 36 and a gap is created between successive dewatering foils. Thus, the layer 15 is subjected to successive pulses which improve the removal of water. The vacuum in a foil box improves the dewatering.

In the embodiment of Figure 2 the second and the third chamber 75, 76 and in the embodiment of Figure 3 only the third chamber 76 act to the layer 15 via sections 41 having a plurality of spaces 78. Each suction chamber 75, 76 is in open communication with its own group of spaces 78 in order to suck up the white water sucked out of the layer 15 through the top wire 36. In addition, at least in the embodiment of Figure 2 the slats 79 may act also as a foils. In the embodiment of Figure 3 the slats 74 in the upper table 69 separated by spaces 78 are to deflect the small quantity of white water that is sucked out of the layer 15 in upward direction. According to one embodiment the width of the slats 79 may be 5 - 50 mm and the width of the spaces 78 may be 5 - 50 mm.

In addition, the upstream end of the upper table 69 may have a slat 80 which scrapes gently against the top wire 36 in order to deflect the white water that collects on the upper side of the top wire 36. The upper table 69 may have a first or leading straight zone 82 and a second or final curved zone 83 with large radius .

The lower run of the secondary forming unit 34 is arranged so that it converges in the direction of travel of the wire 16 of the first forming unit 24. The convergence may be regulated by the position of the lower guide roll 59 and the inclination of the dewatering means 50 by the adjustment means (not shown). In other words, the inclination angle a (Figure 2 and 3) between the top wire 36 running on the area of the dewatering means 50 i.e. after the lower guide roll 59 and the upper run 23 of the wire 16 may be adjusted. The inclination of the lower run of the top wire 36 i.e. the upper table 69 of the housing 71 form an angle a of 1 - 45°, preferably 5 - 20°, with a reference plane that is the upper run 23 of the wire 16.

The adjustment of the inclination angle a may be performed according to one embodiment by adjusting the position of the entirety 49 which includes the lower guide roll 59 and also the dewatering means 50. The position of this structure entirety 49 may be adjusted by adjustment means (not shown) enabling, for example, the entirety 49 to be raised, lowered and/or rotated in order to adjust an inclination angle a. The pivot point 48 of the entirety 49 may be at the right low corner of the housing 71 i.e. in the last dewatering slat 79, for example.

In addition, the whole unit 34 may also be adjusted for this purpose. By means of this converging set-up it is possible to control the amount of water remaining in the layer 15 formed by the secondary forming unit 34 in order to retain a fluidized state in the layer 15 on the lower part of the layer 15. On the other hand, the set-up contribute to enough water being retained in the web layer 15 during its forming to prevent the fibres from "freezing". This inclination angle a makes possible to get short and low secondary forming unit which is important issue in rebuilds.

The top wire 36 of the secondary forming unit 34 running in a loop over guide rolls 38, 59 are to be brought together with the wire 16 of the first forming unit 24 of the hybrid former 27 for couching together the layer 15 formed by the secondary forming unit 34 with the formed two, three or multi-layer web 12, 13 to form the finished multi-layer web 11. This bringing takes place after the lower guide roll 59 and possible also after the dewatering means 50. In the embodiment of Figure 2 this converging has been done after the dewatering means 50. The separate combining unit 30, for example, suction box (or roll nip) located also in area of the loop of the top wire 36 assists this. Thus, after the dewatering means 50 may be arranged a separate combining unit 30 in order to combine the web layer 15 formed by means of at least one secondary forming unit 34 to the at least one web layer 12, 13 being on the wire 16 of the first forming unit 24. In the embodiment of Figure 3 converging has been done already in the area of the dewatering means 50 in connection with the effect area 41 of the latest suction chamber 76.

Owing to the invention i.e. combining the layers together after the waterline has been achieved a very good controllability for adjusting bonding consistency. In addition, the concept forms in capacity point of view good consistency profile to the bottom side of layer 15, which will be combined together with other layers 12, 13 running in the wire 16 of the first forming unit 24. Top side of the layer 15 thickens to high consistency due to vacuum suction box 74 - 76 on that side of the layer 15 and bottom side of the layer 15 will remain with low consistency for ensuring good bonding strength. This can be controlled by suction box vacuum level online control. In addition, average consistency of the layer 15 will be higher than in state of the art solutions, but the side of the layer 15 which will be combined will remain on wet enough.

Figure 4 shows a lateral view of a forming section 10 of a board machine according to another embodiment. Now the forming section 10 includes again the hybrid former 27 and three secondary forming units 34, 44, 54 for manufacturing a four-layer paperboard web 11. By means of the first forming unit 24 has been formed a first layer 12 of the web 11, designated now back layer 13. In this case the headbox 25 of the first forming unit 24 is a single layer headbox.

The secondary forming section including now three separate sections B - D includes in the first section B the first secondary forming unit 44 for forming a second layer 13, designated core. The core is formed by stock with a consistency of 6 - 15%, preferably 8 - 12% being supplied to the top wire 36 of the first secondary unit 44 from a headbox 35, and is dewatered before being converged the wire 16 of the first forming unit 24 carrying the back layer 12 formed previously in the first forming unit 24 and a top wire 36 of said first secondary forming unit 44 and under the influence of an upper table 69 having areas 28 with holes 29 and slats 78 separated by spaces 79, in the loop of the top wire 36.

In addition, the secondary forming section includes in the second section C the second secondary forming unit 54 for forming a third layer 14, designated an underliner. The underliner is formed by stock of a consistency of 0.3 - 1.4%, being supplied to the top wire 36 of the second secondary unit 54 from a headbox 35. Again, the underliner is dewatered below the secondary forming unit 54 in connection with the run of the top wire 36 of said second forming unit 54 and under the influence of an upper table 69 having areas 28 including holes 29 and slats 79 separated by spaces 78, in the loop of the top wire 36 before being converged the wire 16 of the first forming unit 24 carrying the previously formed back layer 12 and core 13. A third secondary forming unit 34 may be situated in section D for forming fourth layer 15, designated surface layer or a top. That may have an identical construction with the forming units 44, 54 described above.

Again, the three secondary forming units 34, 44, 54 include a headbox 35, a top wire 36 and dewatering means 50. Downstream of the headbox 35 is a support table 37 for the wire 16 of the first forming unit 24. As can be seen in Figure 4, the top wire 36 of the secondary forming units 34, 44, 54 runs over a plurality of guide rolls 38 and in an accompanying run 47 within said sections B - D for cooperation with the upper run 23 of the wire 16 of the first forming unit 24. The headbox 35 of the forming units 34, 44, 54 is designed to emit jets of stock with low consistency within the interval 0.5 - 1.0%.

All of the secondary forming units 44, 54, 34 are arranged to form the layers 13 - 15 in cooperation with the upper run 23 of the wire 16 of the first forming unit 24 within the successive sections B - D of the hybrid former 27. The layers 13 - 15 and the wires 16, 36 form the sandwich structure including the top wire 36, wire 16 of the first forming unit 24 and the web layers enclosed therebetween at least partial distance on each of the sections B - D. This distance may be downwards of the dewatering means 50 to the guide roll 38 from which the top wire 36 runs up in the loop.

According to the embodiment disclosed in Figures 1 and 4 a separation suction box 37 is also arranged below and along the wire 16 of the first forming unit 24 at the end of the run of the top wire 36 where the top wire 36 diverges from the wire 16 of the first forming unit 24, so that the multi-layer web accompanies the wire 16 of the first forming unit 24 forwards. The separation suction box 37 may have curved surface, along which the wire 16 of the first forming unit 24 slides. A suction box 37 of the extended hybrid former 27 causes the layer formed of the secondary forming unit 34 to adhere to the lower wire 16 so that the web can subsequently be transferred to the possible next secondary forming unit or at the suction couch roll 18 to the press section of the board machine. In other words, the separation suction box 37 is arranged to ensure that the multi-layer web formed does not follow the top wire 36 of the secondary forming unit 34.

In addition, inside the wire loop 16 of the first forming unit 24 is arranged also suction boxes 32 (Figure 1 and 4), or corresponding means, to remove the air from the closing gap 45 of the secondary forming unit 34. This air is sucked downwards through the wire 16. In general, part of the air, which is drifting to the gap 45, may be sucked through the layer 15 upwards by means of the slit 40 or downwards by means of the suction box 32. Additionally, these suction boxes 32 confirms that the web being already on the wire 16 stays there and does not disturb the layer 15 formed by the secondary forming unit 34 .

Inside the wire loop 16 of the first forming unit 24 is arranged also suction boxes 33 (Figure 1 and 4), or corresponding means, between the sections at the beginning of the secondary forming units 34, 44, 54 to remove the air before the upper run 23 of the wire 16 goes under the headbox 35 of the secondary forming unit 34. This air is sucked downwards through the wire 16. Additionally, these suction boxes 33 confirm that the layer being already on the wire 16 of the first forming unit 24 stays there and does not disturb the layer 15 formed by the secondary forming unit 34.

If desired, the amount of the secondary forming units may vary. The forming section 10 may include, for example, 2 to 4 secondary forming units 34, 44, 54. The secondary forming units may have the same design, for example, as the forming units described just above. The plurality of secondary forming units is also effective in terms of energy because it is easier to dewater the plurality of thin layers, if compared to one thick layer .

In addition, at least part of the secondary forming units 34 may have been equipped with the moving mechanism 31 in order to bring them in connection with the wire 16 of the first forming unit 24 and removing, correspondingly. This allows to produce more grades by means of the same machine efficiency in terms of energy.

In addition, one more aspect of the invention is the secondary forming unit 34, 44, 54 for a multiply forming section 10 of a fiber web machine. This kind of secondary forming unit 34, 44, 54 may be applied in rebuilds, for example. The secondary forming unit 34 includes a headbox 35 including a slice opening 21 and guide rolls 38, 59 around which a top wire 36 running in a loop can be arranged. In addition, the secondary forming unit 34, 44, 54 includes also a suction box 50 for dewatering inside the loop of top wire 36 which includes a housing 71 and an upper table 69. In the area of the guide roll 59 the run of the top wire 36 is arranged to be directed towards the upper table 69 of the suction box 50. The headbox 35 is arranged to supply the stock to the surface S of the top wire 36 after the guide roll 59. The slice opening 21 of the headbox 35 is arranged to locate below the guide roll 59. The upper table 69 of the suction box 59 is arranged to locate in the lower portion of the housing 71 and the dewatering is arranged to take place essentially towards the suction box 59. A fiber web machine is advantageously a board machine, but it can also be a speciality paper machine or printing paper machine .

It is to be understood that the above description and the related figures are only meant for illustrating the present method and arrangement according to the invention. Thus, the invention is not only limited to the embodiments proposed above or those defined in the claims, but many different variations and modifications of the invention, which are possible within the inventive idea defined in the appended claims, will be evident to those skilled in the art.

Claims

A forming part of a fiber web machine, said forming part (10) comprising a plurality of forming units (24, 34, 44, 54), comprising: - a first forming unit (24) for forming at least a first web layer (12, 13); one secondary forming unit (34) for forming a second web layer (15), the secondary forming unit (34) comprising - a headbox (35) having a lip opening (21), a top wire (36) in rotation and having a wire (16) for the first forming unit (24). co-operating passage (47), and a lower guide roll (59) and subsequent dewatering means (50) located within the upper wire (36) rotation, characterized in that the headbox (35) of at least one secondary forming unit (34) is adapted to feed pulp ) on the surface (S) in the region of the dewatering means (50) after the lower guide roll (59), the lip opening (21) of the headbox (35) is arranged disposed in the region (45) between the lower guide roller (59) and the wire (16) of the first forming unit (24).

A forming member according to claim 1, characterized in that the dewatering means (50) include an upper table (69) disposed on the underside of the housing (71), which housing includes suction chambers (74-76) immediately adjacent to the lower guide roll (36). 59).

The forming part according to claim 1 or 2, characterized in that the dewatering means (50) of the at least one secondary forming unit (34) are of at least partially non-pulsed type.

A forming part according to claim 2 or 3, characterized in that the upper table (69) comprises a plurality of openings (29) and / or elongated moldings (79) spaced apart (78). A forming part according to any one of claims 1 to 4, characterized in that the inclination angle (?) Between the upper wire (36) passing through the area of the dewatering means (50) and the upper wire (23) of the wire (16) is preferably 1 ° to 45 °. . A forming part according to any one of claims 1 to 5, characterized in that, after the dewatering means (50), a separate combining unit (30) is arranged to connect the web layer (15) formed with at least one secondary forming unit (34) to at least one web layer (12). , 13).

A forming part according to any one of claims 1 to 6, characterized in that the forming part (10) comprises two to four secondary forming units (34, 44, 54). A forming part according to any one of claims 1 to 7, characterized in that at least a portion of the secondary forming units (34) are provided with a movement mechanism (31) for engaging and removing them from the wire (16) of the first forming unit (24). A secondary shaping unit for a fibrous web for multi-layer forming of a machine, the secondary forming unit (34) comprising: - a head box (35) including a lip opening (21), - guide rollers (38, 59) surrounded by a circular upper wire (38). 36) can be fitted, - a suction box (50) for dewatering inside a rotation of the upper wire (36) including a housing (71) and an upper table (69), and wherein - in the region of the guide roller (59) ) top table (69), characterized in that the head box (35) is adapted to supply mass to the surface (S) of the upper wire (36) in the region of dewatering means (50) after the guide roll (59); 59) below.

A secondary forming unit according to claim 9, characterized in that the upper table (69) of the suction box (59) is arranged to be located at the lower part of the housing (71) and the dewatering is arranged substantially towards the suction box (59).