DE2543495A1 - METHOD AND APPARATUS FOR MANUFACTURING MULTI-PAYERED FIBER WEBS LIKE PAPER FROM DILUTED FIBER PULP - Google Patents

Description

Method and device for the production of multi-layer 3-fiber webs such as paper diluted pulp

The invention relates to a working method and a device for producing multilayered fiber webs such as paper from thinned paper Pulp by removing a single headbox from a headbox stratified material flow, consisting of an upper and a lower layer, on a substantially horizontal path moving water-permeable screen belt. is applied.

The production of multilayered fiber webs has problems due to increasing machine speeds and quality requirements with regard to the mode of operation and the design of paper machines, both of which are becoming increasingly complex and costly machine effort as well as more sophisticated procedures,

. Originally one had material flow layers of different consistencies placed one after the other on a forming surface and the layers are brought together after they have been completely or partially drained. For example, one has In the manufacture of two-layer paperboard the base sheet, which is normally at least 65 ^ of the paperboard combined with the Covering layer comprises, shaped and the same drained at a point outside the drying line, then around the covering to be applied to the base web by means of a second feed box. Since the base track is only partially drained, before the topping is applied, aas 7 / water must be removed from the topping through the pasers of the basic line * The pasers of the basic

Telephone: (00894) 14396, apartment 7124 · Accounts

13 28-4S, Roechling Bank St. Ingberf 20.013.490

Bahn are however already oriented in the manner of a hat and thus represent a physical obstacle for the water, that has to be removed from the surface on the base track. To avoid this, it was suggested earlier to use a add the upper sieve belt, which begins shortly after the point where the upper layer is applied to the lower layer in order to dewater the upper layer through the upper screen belt in the upward direction (US Pat. No. 3,385,754; 2,881,670 and 3 255 074).

Mt. the making of the invention described in US patent application Ser.No.434 048 it has become possible to reply to the foruijnende Surface from a single, multi-layer material flow Apply paper pulp. The invention uses this technique in an improved manner to make a fibrous web for layered paperboard on a single-wire paper machine in solving the problem of allowing proper drainage of the upper layer of pavement through the base sheet. The solution to this problem is procedurally that the lower layer to a smaller volume respectively. a smaller one Thickness is set as the top layer. This ensures that the upper layer quickly passes through the lower layer can be dehydrated, as this is due to their lower Volume is drained faster. A merging 'respectively. Mixing of the two layers is prevented by the method according to the invention.

The partial flow of material for the lower layer expediently contains bleached material Kraft paper pulp, whereas the partial flow of pulp for the top layer appropriately contains unbleached Kraft paper pulp.

The invention also relates to a device for carrying out the working method "consisting of a headbox, which is set up to deliver a single layered stream of material is, and a substantially horizontal moving water-permeable screen belt on which the layered Material flow is given up, with the headbox through a slot-shaped outlet opening Reaching partition is divided into two chamber sections, each of which is assigned a material feed. This is for double screening machines according to DT-OS 2 258 781 known.

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The novelty is that the dividing wall has two chamber sections Forms unequal volume, of which the lower chamber has a smaller volume than the upper chamber, so that a lower one from the slit-shaped outlet opening of the headbox Layer runs out, which has a smaller thickness than the upper layer «.

As is known, the partition is designed to be flexible at its tail end directed downstream, so that different pressure conditions can be achieved can freely adjust between the two material flows and the material flows always at the same speed exit the headbox.

In the drawing is an embodiment of the invention Device shown in comparison to the prior art, namely show

1 shows a schematic representation of the Pormzone · -. "_ ■; '.. ^; Of a paper machine for the production of two-ply paper with two head boxes according to the prior art,

Mg.2 a schematic representation of an outside of the Protection lying arrangement with only one headbox,

Pig, 3 is a schematic representation of a forming zone for the production of a two-ply Paserbahn according to the Er-. finding,. ^v

Pig.4 shows a partial cross-section through the on one Pormzone produced according to Fig. 2,

Pig. 3 fine cross-section of the same kind through the Paserbahn produced on the Pormzone according to Pig. 3, and

Pig.6 is a schematic side view of a headbox according to the invention for the delivery of two substances ~ Partial flows of different thicknesses.

The Pormzone of the paper machine known from Pig, 1 has an endless screen belt 10 which is guided around a breast roll 11 and on a horizontal path over a forming table 12, Ti ε ehr olliin 13 and suction boxes 14 and 15 is performed. A first material

\ Laufkasten 16 places a layer of material 17 on the sieve belt 10. This location, referred to below as the base line, is represented by '

> the molding table 12, the table rollers 13 and the suction boxes 14 waters, which is followed by the dry line. A screen roller

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18 is provided to gate the top surface of the base web. to smoothen the application of the second layer, which will be referred to below as the "topping" deposits a second layer or pavement on base sheet 17 at a point beyond the drying line. It was necessary To apply the covering to the base sheet at a point beyond the drying line, as the base only becomes sufficiently stable in the drying line, i.e. the fibers are sufficiently intertwined are to withstand the abandonment of the pavement without serious disturbances in the formation of the base path to have to accept. It should be noted that the known arrangement has two headboxes 16 and 19 and an orphan sieve 18 required

Pig, 2 shows how one can draw on the lessons of the state of the art Technology according to Eig.1 with the teachings according to the said US patent application Ser.STo. 434 048 can combine. As Pig. 2 shows a water-permeable sieve belt 20 is guided around a breast roller 21 and migrates along a horizontal plane a forming table 22 and table rollers 23. A single feed box 24, which is provided with fabric supply chambers 25 and 26 is, is located above the breast roll 21 in order to place a two-layer material flow 27 on the screen belt 20. The material flow 27 comprises two layers 27a and 27b. The layer 27a represents the upper surface, whereas the layer 27b represents the base sheet. Typically the top layer of pavement would not account for more than about 35-6 of the total weight of the combined sheet, whereas the basic line comprises the remaining 65% and the base sheet would normally be made from brown paper stock such as unbleached Kraft paper pulp, whereas the facing layer 27a is made of white or bleached pulp would exist.

The known arrangement according to Mg, 1 has proven to be unacceptable proven to the extent that it could not be used to produce multilayer cardboard with a top layer of a quality such as it is required in today's industrial standards. As already shown in connection with Pig. 1, the base track 17 must be on a Place beyond the dry line to be drained before the

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Covering is applied in order to prevent a disturbance in the formation of the base web and a mixing of the cover with the base web. It should be noted that with an arrangement according to Pig.2 the base web 27b is unformed for quite a period of time . ■ ■ ~ remains, and due to the movement of the material, which occurs naturally on a single sieve belt, a niche between the covering 27a and the base web 27b is inevitable. The problem presented in connection with Pig.2 is to be seen in the fact that the period of time required for "setting" or "fixing" the fibers of the base sheet 27b is too long, so that a mixing of the fibers of the base sheet with the fibers of the covering is inevitable will. This mixing process is shown diagrammatically in Pig. 4, which shows a section through the mixed fibers of the covering and the base sheet. It is clear to a person skilled in the art that a conventional screen belt table design favors the movement and the tipping of the reshaped fibers, with the result that better shape formation is achieved through delayed flocculation. This type of table is therefore unsuitable for the formation of a two-layer web, in which the base web is first placed on the sieve belt. ,

The solution to the problem is shown in FIG. At this pore formation zone a screen belt 28 is guided around a breast roller 29 and moves in a horizontal path over a forming table 30, table rollers 31 and wire belt supports 32. A headbox 32 delivers a two-layer material flow to the screen belt 28, wherein the headbox is divided into two / one chambers 34, 35. The partial streams of stock coming from the headbox are denoted by 36a and 36b, namely 36jt> the upper covering layer and 36a the base web which is applied to the sieve belt and is covered by the pavement layer. According to the invention, the 'Grundbahn has a weight proportion of 35 / q of the total weight of the combined material flow (preferably 2550 · As a result the covering 36b. , quickly drained through the sieve belt, since the pavement is not drained through the pasers of the base sheet is delayed, as is the case with the known arrangements of the pail. Ss it is noted that since the required time

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for dewatering .. the covering 36b and for "setting" or "fixing" its fibers are drastically reduced - the upper covering. layer 36b will "set" or "fix" before any we-. significant sound of the "two layers can occur. The Any water remaining in the base web 36a can easily pass through the fibers of the covering 36b can be dewatered without having to fear adverse effects.

In a typical embodiment of the method according to the invention, the speed of the screen web was about 300 m / min set, with the material flow at the same speed. V. ·. · .-- ■ "'.'_' .. was applied and where also the fabric part for the base sheet made of a bleached kraft paper stock with a weight of 19 g / m and the top layer consisted of unbleached Kraft paper stock at 105 g / m 2. A two-layer web was formed with the layers firmly bonded together with no substantial mixing between them Locations.

Fig.6 shows a particular headbox as it is in connection is used with the invention. The headbox 40 is provided with an inlet which is passed through a partition 42 in FIG two inlet chambers 41a and 41b is divided. The partition wall 42 and the inlet chambers extend over the full width of the Fabric overflow box 40. The fabric entering chamber 41a flows through a series of diffusers 43a to 43d into an antechamber 44a, whereas the substance flowing into the chamber 41b flows through a series of diffusers 43e into the antechamber 44a. The chambers 44a and 44b are separated from one another by a partition 45 which, like the antechambers 44a and 44b "Extends the full width of the casserole box .. Downstream directed end of the chambers 44a and 44b is a perforated Wall 46 is provided through which the partial flows of matter in a converging slot chamber 47 open out. The slot chamber 47 runs out into a slot-shaped outlet opening 48, which is divided by a flexible partition wall 49 into two slot chambers 47a and 47b. The partition wall 49 extends over the full machine width of the slot chamber 47 and extends from the perforated wall 46 to the outlet opening 48, the Schiitzkammern 47a and 47b are also provided with flexible guide elements 50. It should be noted that the flexible partition wall 49

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has a first flexible part 49a, to which a second relatively stiff part 49b is connected, which in a '■ relatively flexible tail end 49c runs out. The construction of the flexible partition wall 49 is described in detail in US patent application Ser. No. 303,972.

It is important that the flexible tail end 49c of the partition wall 49 extends as far as the flank of the outlet opening 48, do to maintain a clear separation between the partial material flows, which on the one hand go through the parts 41a, 43a, b, c, d, -, 47a and on the other hand through 41b, 43e, 47b so that two flow _In certain ways, layers of various Fabric consitsζ and thickness leave the outlet opening « It is also important that the flexible tail end 49c ensure that the speed of the layers of fabric 50a and 50a 50b is kept the same. Should for some reason .'der Pressure in the slot chamber 47a change, the flexible end 49c adjusts itself to a pressure equalization that the speed of the material flow remains constant.

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Claims (5)

Claims 1. Working method for the production of multi-layered fiber dummies vie paper made from diluted pulp, in that one Headbox a single layered material flow, "consisting of an upper and a lower layer, on one Water-permeable "moving" essentially in a horizontal path Sieve belt is applied, characterized in that the lower layer "(36a) on a smaller Yolumen resp. is set to a smaller thickness than the upper layer (36b). 2, method according to claim 1, characterized in that the partial flow of material for the lower layer (36a) is bleached Kraft contains 3. The method according to claim 1, characterized in that the partial flow of pulp for the upper layer (36b) contains unbleached kraft paper pulp, , 4. Device for performing the method according to claim 1, • Consists of a substance overflow box, which is used to dispense a single layered material flow is established, and a water-permeable sieve belt moving essentially in a horizontal path, onto which the layered Material flow is abandoned, with the headbox is divided into two chamber sections by a partition wall reaching into its slot-shaped outlet opening, each of which is assigned a St off feed, characterized in that the partition (42,45 »49) has two Eainmer sections (41a, 44a, 47a or “41b, 44b, 47b) are unequal Volume forms, of which the lower chamber is a smaller one _ o_ Telephone: (06894) 14396, apartment 7124 · Accounts: Postscheckamt Essen 1013 $ 28-43, Gebr. Röchling Bank St. Ingbert 20.013.490 609816/0771 Has volume than the upper chamber. 5. Apparatus according to claim 4, characterized in that, the partition at its downstream tail end (49) "is designed to be flexible. 609816/0771 Blank page