DE102019126296A1 - Lamella for a headbox and method for producing a lamella - Google Patents

Abstract

The invention relates to a lamella (1) suitable for installation in a nozzle (17) of a headbox (16) of a paper machine for separating two suspension streams flowing through the nozzle (17), with a lamella body (3) having a lamella body width, a lamella body length ( 4) and a lamellar body thickness (5) and a downstream end (8), and the lamellar body length (4) and the lamellar body width span a first flow surface (6) and a second flow surface (7) opposite the first flow surface (6) and on the downstream At the end (8) on the first flow surface (6) or on the second flow surface (6) a film (13) protruding beyond the downstream end (8) of the lamellar body (3) is attached that the film (13) protrudes by a protrusion (14) beyond the downstream end (8) of the lamellar body (3) and the protrusion (14) is greater than 0.5 mm, in particular greater than 1 mm , preferably greater than 1.5, very particularly preferably greater than 2mm.

Description

The invention relates to a lamella which is suitable for installation in a nozzle of a headbox of a paper machine for separating two suspension streams flowing through the nozzle, with a lamella body which has a lamella body width, a lamella body length and a lamella body thickness and a downstream end, and the lamella body length and the lamellar body width spans a first flow surface and a second flow surface opposite the first flow surface and a film projecting beyond the downstream end of the lamellar body is attached at the downstream end on the first flow surface or on the second flow surface.

Devices of this type are known. The document DE4329810 A1 discloses a lamella of a headbox of a paper machine with an end area. To avoid or reduce periodic vortex shedding, various embodiments of the end region of the lamella are proposed. In one example, the end of the lamella is provided with a film which protrudes beyond the end of the lamella. The film is attached to the top or bottom of the slat.

With the known solutions, the effects of the vortex shedding on the quality of the paper web produced can only be reduced in a certain operating window, for example a small speed range. In addition, the structure of the lamella is not satisfactory in terms of cost and function.

The object of the invention is therefore to improve the structure and function of a lamella of a headbox of a paper machine, as well as to specify a method for producing a lamella and to propose a headbox for a good jet quality with at least one lamella.

The object is achieved by the features of claim 1. A lamella is proposed which is suitable for installation in a nozzle of a headbox of a paper machine for separating two suspension streams flowing through the nozzle. The lamella comprises a lamella body which has a lamella body width, a lamella body length and a lamella body thickness and a downstream end, and the lamella body length and the lamella body width span a first flow surface and a second flow surface opposite the first flow surface and at the downstream end on the first flow surface or on the second flow surface a protruding over the downstream end of the lamellar film is attached. The invention is characterized in that the film protrudes by an overhang over the downstream end of the lamellar body and the overhang is greater than 0.5 mm, in particular greater than 1 mm, preferably greater than 1.5, very particularly preferably greater than 2 mm .

The lamellar body length extends in the direction of the flowing suspension streams and the lamellar body width extends transversely thereto.

The film preferably extends over the entire width of the lamella body.

The solution according to the invention has the advantage that the vortices shedding at the downstream end of the lamellar body do not have an effect beyond the film area. As a result, on the one hand, a good paper quality can be achieved without disturbances caused by hydraulics and, on the other hand, in the case of a multi-layer headbox, a good layer separation of the different layers can be achieved.

It is also advantageous if the film protrudes by an overhang beyond the downstream end of the lamellar body and the overhang is less than 50 mm, in particular less than 30 mm, preferably less than 20, very particularly preferably less than 10 mm. If the overhang is chosen to be larger, there is a risk that, under certain operating conditions, the film itself will generate disturbances in the flow and will flutter. In addition, the mechanical stress on the connection between the film and the lamellar body increases. This can lead to loosening of the connection.

The lamellar body thickness is preferably in the range from 3 mm to 6 mm, preferably in the range from 3.5 mm to 4.5 mm.

The lamellar body thickness can be reduced at the downstream end by a bevel on the first flow surface and / or on the second flow surface to a final thickness between 0.2 mm and 2 mm, in particular between 0.5 mm and 1 mm. The first flow surface and the second flow surface thereby form a point at the downstream end of the lamellar body with a point angle. This reduces the formation of eddies and increases the operating window.

It is particularly advantageous if the bevel has a first bevel angle to the first flow surface and / or a second bevel angle to the second flow surface. The point angle has values in the range from 1 ° to 9 °, in particular in the range from 1.5 ° to 6 °, preferably in the range from 2 ° to 5 °. At If the bevel is on one side, the bevel angle corresponds to the tip angle of the lamellar body.

In the case of a double-sided bevel, the sum of the two bevel angles corresponds to the tip angle of the lamellar body. The lamellar body is preferably beveled symmetrically so that the first bevel angle is equal to the second bevel angle. Here, too, the point angle has values in the range from 1 ° to 9 °, in particular in the range from 1.5 ° to 6 °, preferably in the range from 2 ° to 5 °.

The film can be attached over the entire length of the lamellar body or only on part of the length of the lamellar body.

If the film is only connected to the lamellar body in the area of the downstream end, the film can be arranged sunk in the corresponding flow surface.

The foil is preferably connected to the lamellar body by gluing or welding.

It is particularly advantageous if the film has a film thickness between 0.05 mm and 0.3 mm, in particular between 0.1 mm and 0.2 mm.

It is also possible for the lamella to be designed in such a way that the film material differs from the lamella body material or that the film material differs from the lamella body material in terms of mechanical properties as a result of mechanical or thermal treatment. As a result, the components, such as the lamella body and the film of the lamella, can be optimized in terms of construction according to the specific requirements and with regard to costs. The lamellar body must have a minimum rigidity in order to maintain the geometry of the flow channels in the nozzle. The foil, on the other hand, has to be just so soft that no eddies are induced in the flow and the eddies created at the end of the lamellar body are dampened.

In the event that the lamellar body material and the foil material are the same, the foil material can be treated mechanically by monoaxial or biaxial stretching, for example in the direction of the lamellar body length or additionally in the direction of the lamellar body width, before it is connected to the lamellar body. Optionally, heat can also be used. By stretching, the flexural rigidity can be optimized with otherwise unchanged geometry parameters.

The lamellar body material can be selected from the following group of materials: plastic, CFRP (carbon fiber reinforced plastic, PPSU (polyphenyl sulfone), PC (polycarbonate), PET (polyethylene terephthalate), PE (polyethylene), metal.

CFRP as a material is particularly advantageous in terms of dimensional stability, thermal and chemical properties and weight and due to the structural options in terms of structure.

The film material can be selected from the following group of materials: plastic, PET (polyethylene terephthalate), PC (polycarbonate), PE (polyethylene), metal.

The material PET is particularly suitable for monoaxial or biaxial stretching to optimize flexural rigidity.

The object is also achieved by a headbox with a turbulence generator and a nozzle, at least one lamella according to the invention being used in the nozzle.

The nozzle of the headbox has a nozzle length. The lamella length of the at least one lamella can be shorter or longer than the nozzle length. This means that the lamella can on the one hand end inside the nozzle and on the other hand can end outside the nozzle.

If several lamellas are used in a headbox nozzle, part of the lamellae can end inside and the remaining part outside the nozzle.

The length of the lamellas can be different.

The lamella can be used in a single-layer headbox operated with just one fiber suspension. However, it is also possible to use the lamella in a multi-layer headbox that is fed with at least two different pulp suspensions. The at least two different fiber suspensions are kept separate by the lamella in order to produce a multi-layer fiber web in the subsequent forming section.

The object is also achieved by a method for producing a lamella for installation in a nozzle of a headbox of a paper machine for separating two suspension streams flowing through the nozzle. The lamella comprises a lamella body which has a lamella body width, a lamella body length and a lamella body thickness and a downstream end, and the lamella body length and the lamella body width span a first flow surface and a second flow surface opposite the first flow surface and on downstream end on the first flow surface or on the second flow surface, a film projecting beyond the downstream end of the lamellar body is attached. According to the invention it is provided that the film protrudes by an overhang over the downstream end of the lamellar body and the overhang is selected to be greater than 0.5 mm, in particular greater than 1 mm, preferably greater than 1.5, very particularly preferably greater than 2 mm.

It is also advantageous if the film material comprises a plastic that is stretched monoaxially, preferably in the direction of the protrusion, or biaxially.

Further features and advantages of the invention emerge from the following description of preferred exemplary embodiments with reference to the drawings.

Figure list

• 1 a first embodiment of a lamella according to the invention in a schematic and simplified representation;
• 2 a second embodiment of a lamella according to the invention in a schematic and simplified representation;
• 3 a third embodiment of a lamella according to the invention in a schematic and simplified representation;
• 4th a fourth embodiment of a lamella according to the invention in a schematic and simplified representation;
• 5 an embodiment of a headbox with lamellae according to the invention in a schematic and simplified representation;

In the 1 to 4th are different embodiments of a lamella according to the invention 1 shown in a schematic and simplified representation. The slats 1 are shown in these examples in their length significantly shortened relative to the thickness in order to be able to see the details better. The lamella according to the invention 1 is for installation in a nozzle 17th a headbox 16 a paper machine provided. It is used there to separate two through the nozzle 17th flowing suspension streams as in 5 shown. The lamella 1 can be used in a single-layer headbox that is operated with only one pulp suspension. However, it is also possible to use the lamella 1 to be used in a multi-layer headbox that is fed with at least two different pulp suspensions. Thereby are through the lamella 1 the at least two different fiber suspensions are kept separate in order to produce a multi-layer fiber web in the subsequent forming section.

The lamella 1 to 1 comprises a lamellar body 3 , the one lamellar body width, one lamellar body length 4th and a lamellar body thickness 5 and a downstream end 8th having. The lamellar body length 4th and the lamellar body width, which is in the plane of the drawing and perpendicular to the lamellar body length 4th is directed, span a first flow surface 6th and one of the first flow area 6th opposite second flow surface 7th on. At the downstream end 8th is on the first flow surface 6th or on the second flow surface 7th one over the downstream end 8th of the lamellar body 3 protruding film 13th attached. The film material is plastic, preferably PET, and in this example differs from the lamellar body material, which is designed as CFRP.

The foil is before joining with the lamellar body 3 biaxial or monoaxial, preferably in the direction of the protrusion 14th , stretched. This increases the mechanical properties of the film 13th optimized, i.e. changed with regard to the function of avoiding or dampening flow vortices. The required flexural rigidity can be achieved with a small film thickness. The foil 13th protrudes from an overhang 14th over the downstream end 8th of the lamellar body 3 out and the supernatant 14th is greater than 0.5 mm, in particular greater than 1 mm, preferably greater than 1.5, very particularly greater than 2 mm. The supernatant 14th the slide 13th is preferably smaller than 50 mm, in particular smaller than 30 mm, preferably smaller than 20 mm, very particularly preferably smaller than 10 mm. The lamellar body thickness 5 is in the range from 3mm to 6mm, preferably in the range from 3.5mm to 4.5mm. The lamellar body thickness 5 is in 1 at the downstream end 8th by a bevel on the first flow surface 6th to a final thickness 9 between 0.2mm and 2mm, in particular between 0.5mm and 1mm. The first flow surface 6th and the second flow surface 7th form a peak at the downstream end 8th of the lamellar body 3 with an apex angle 2 out. The bevel in the execution of the 1 has a first bevel angle 10 to the first flow surface 6th in the range from 1 ° to 9 °, in particular in the range from 1.5 ° to 6 °, preferably in the range from 2 ° to 5 °. The value of the bevel angle 10 corresponds to the point angle 12th . The foil 13th is only on part of the lamellar length 4th , in this example by gluing, attached and lies on the second flow surface 7th on. The foil 13th has a film thickness 15th between 0.05mm and 0.3mm, in particular between 0.1mm and 0.2mm.

The second embodiment of a lamella according to the invention 1 to 2 differs from the execution according to 1 only by the fact that the foil 13th in the second flow area 7th is arranged sunk. The advantage of this design is that the foil 13th no abutting edge forms.

In the third embodiment of a lamella according to the invention 1 in 3 is the slide 13th on the slope of the first flow surface 6th placed and fixed by gluing.

The 4th shows another embodiment of the lamella 1 where the bevel on both sides of the lamella 1 was executed. In the case of this two-sided bevel, the sum of the two bevel angles corresponds 10 , 11 the point angle 12th of the lamellar body. The values of the point angle 12th in this example are also in the range from 1 ° to 9 °, in particular in the range from 1.5 ° to 6 °, preferably in the range from 2 ° to 5 °. The lamellar body is preferably 3 symmetrically beveled so that the first bevel angle 10 equal to the second bevel angle 11 is. The foil 13th is on the slope of the first flow surface 6th placed and fixed by gluing.

The 5 shows an embodiment of a headbox 16 with two slats according to the invention 1 in a schematic and simplified representation. The headbox 16 includes a turbulence generator 19th and a nozzle 17th . This headbox 16 is suitable as a multi-layer or single-layer headbox. The pulp suspension flows through the turbulence generator, which includes a tube bundle 19th and flows in the direction of flow 20th then through the nozzle. In the case of a single-layer headbox, the lamellas diminish 1 on the one hand, coarse eddies in the flow of the pulp suspension and, on the other hand, they avoid the formation of eddies at the end of the lamellae 1 . In the case of a multi-layer headbox, the slats hold 1 separate the different fiber suspensions and guide the different fiber suspension layers at the end of the lamellae 1 gently, i.e. without vortex formation, so that a layer separation is maintained even after the end of the lamellae. The first flow surfaces 6th of the slats 1 are through the top of the slats 1 and the second flow surfaces are formed accordingly 7th through the underside of the slats 1 educated. The first flow surfaces 6th of the slats 1 can also go through the underside of the slats 1 be formed and accordingly the second flow surfaces 7th through the top of the slats 1 be educated. It is also possible that the first flow surface 6th the upper lamella 1 through the underside of the slat 1 is formed and the first flow surface 6th the lower lamella 1 through the top of the lower lamella 1 is formed. The orientation of the position of the lamellas in the nozzle 17th is therefore freely selectable. The length of the lamellas 2 are shorter than the nozzle length in this example 18th executed. They therefore end inside the nozzle.

Corresponding elements of the exemplary embodiments in the figures are provided with the same reference symbols. The functions of such elements in the individual figures correspond to one another, unless otherwise described and it does not lead to contradictions. A repeated description is therefore dispensed with. It is also pointed out that the distinguishing features of the exemplary embodiments shown can be exchanged for one another and combined with one another. The invention is therefore not limited to the combinations of features shown in the exemplary embodiments shown.

List of reference symbols

1

Lamella

2

Slat length

3

Lamellar body

4th

Lamellar body length

5

Lamellar body thickness

6th

first flow surface

7th

second flow surface

8th

downstream end

9

Final thickness

10

first bevel angle

11

second bevel angle

12th

Point angle

13th

foil

14th

Got over

15th

Film thickness

16

Headbox

17th

jet

18th

Nozzle length

19th

Turbulence generator

20th

Direction of flow

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 4329810 [0002]

Claims (15)

Lamella (1) suitable for installation in a nozzle (17) of a headbox (16) of a paper machine for separating two suspension streams flowing through the nozzle (17), with a lamella body (3) having a lamella body width, a lamella body length (4) and a Has lamellar body thickness (5) and a downstream end (8), and the lamellar body length (4) and the lamellar body width span a first flow surface (6) and a second flow surface (7) opposite the first flow surface (6) and at the downstream end (8) a film (13) projecting beyond the downstream end (8) of the lamellar body (3) is fastened on the first flow surface (6) or on the second flow surface (7), characterized in that the film (13) extends around a protrusion (14 ) protrudes beyond the downstream end (8) of the lamellar body (3) and the protrusion (14) is greater than 0.5 mm, in particular greater than 1 mm, preferably greater than 1.5, very particularly preferably greater than 2mm. Lamella according to one of the preceding claims, characterized in that the film (13) protrudes by an overhang (14) over the downstream end (8) of the lamella body (3) and the overhang (14) is less than 50 mm, in particular less than 30 mm, preferably smaller than 20mm, very particularly preferably smaller than 10 mm. Lamella according to one of the preceding claims, characterized in that the lamella body thickness (5) is in the range from 3mm to 6mm, preferably in the range from 3.5mm to 4.5mm. Lamella according to one of the preceding claims, characterized in that the lamella body thickness (5) at the downstream end (8) by a bevel on the first flow surface (6) and / or on the second flow surface (7) to a final thickness (9) between 0 , 2mm and 2mm, in particular between 0.5mm and 1mm, and the first flow surface and the second flow surface form a point at the downstream end (8) of the lamellar body (3) with a point angle (12). Lamella after Claim 4 , characterized in that the tip angle (12) has values in the range from 1 ° to 9 °, in particular in the range from 1.5 ° to 6 °, preferably in the range from 2 ° to 5 °. Lamella according to one of the preceding claims, characterized in that the film (13) is attached over the entire length of the lamella body (4) or is only attached to part of the length of the lamella body (4). Lamella according to one of the preceding claims, characterized in that the film (13) is arranged sunk in the corresponding flow surface (6, 7). Lamella according to one of the preceding claims, characterized in that the film (13) has a film thickness (15) between 0.05 mm and 0.3 mm, in particular between 0.1 mm and 0.2 mm. Slat according to one of the preceding claims, characterized in that the film material differs from the slat body material and / or that the film material differs in mechanical properties from the slat body material as a result of mechanical or thermal treatment. Slat according to one of the preceding claims, characterized in that the slat body material is selected from the following group of materials: plastic, CFRP (carbon fiber reinforced plastic), PPSU (polyphenyl sulfone), PC (polycarbonate), PET (polyethylene terephthalate), PE (polyethylene), metal . Slat according to one of the preceding claims, characterized in that the film material is selected from the following group of materials: plastic, PET (polyethylene terephthalate), PC (polycarbonate), PPSU (polyphenyl sulfone), PE (polyethylene), metal. Headbox (16) of a paper machine with a turbulence generator (19) and a nozzle (17), characterized in that in the nozzle (17) at least one lamella (1) according to one of the preceding claims for the separation of flowing through the nozzle (17) Suspension streams is used. Headbox after Claim 12 , characterized in that the nozzle (17) has a nozzle length (18) and the lamella length (2) is shorter or longer than the nozzle length (18). Method for producing a lamella (1) for installation in a nozzle (17) of a headbox (16) of a paper machine for separating two suspension streams flowing through the nozzle, with a lamella body having a lamella body width, a lamella body length (4) and a lamella body thickness (5 ) and a downstream end (8), and the lamellar body length (4) and the lamellar body width span a first flow surface (6) and a second flow surface (7) opposite the first flow surface (6) and at the downstream end (8) on the first Flow surface (6) or on the second Flow surface (7) a film (13) protruding beyond the downstream end (8) of the lamellar body (3) is attached, characterized in that the film (13) extends by an overhang (14) over the downstream end (8) of the lamellar body ( 3) protrudes and the protrusion (14) is selected to be greater than 0.5 mm, in particular greater than 1 mm, preferably greater than 1.5, very particularly preferably greater than 2 mm. Device according to Claim 14 , characterized in that the film material comprises a plastic which is stretched biaxially or monoaxially, preferably in the direction of the protrusion (14).

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