WO2006090009A1

WO2006090009A1 - Turbulence element and method for manufacturing a turbulence element

Info

Publication number: WO2006090009A1
Application number: PCT/FI2006/050061
Authority: WO
Inventors: Jarmo Kirvesmäki
Original assignee: Metso Paper, Inc.
Priority date: 2005-02-25
Filing date: 2006-02-13
Publication date: 2006-08-31
Also published as: FI20055093A; FI20055093A0

Abstract

The invention relates to a turbulence element (10) , which is exchangeably fitted in the area of the slice channel (13) of the headbox (11) of a paper machine or similar. The turbulence element comprises an attachment member (16) and a tip part (20) . The attachment member (16) is connected to the frame structure (24) of the headbox (11) . The turbulence element (10) according to the invention is formed of - a base structure (14) , to which the said attachment member (16) and tip part (20) are fitted and - reinforcements (15.1, 15.2) fitted to the top and bottom of the base structure, and which are fitted in the area between the attachment member and the tip part . In addition, the invention also relates to a method for manufacturing the turbulence element (10) .

Description

TURBULENCE ELEMENT AND METHOD FOR MANUFACTURING A TURBULENCE ELEMENT

The present invention relates to a turbulence element, which is exchangeably fitted in the area of the slice channel of the headbox of a paper machine or similar, the turbulence element comprising an attachment member and a tip part and in which the attachment member is connected to the frame structure of the headbox. In addition, the invention concerns also a method for manufacturing a turbulence element.

Irrespective of their name, turbulence elements (also known as sheets or baleens) are used, for example, in the headboxes of paper and board machines. They are flat "plates" in the slice cone, which are attached at one edge to the output end of the turbulence generator.

One task of turbulence sheets is to increase the level of turbulence in the mass flow, with the aid of the wall friction in the accelerating flow in the slice channel, and to maintain it to the slice opening of the channel and as far as the wire section. The orientation of the fibres in the mass flow jet discharging from the headbox will then be increasingly random. This is used to affect the tensile strength of the material being manufactured and its orientation in the different directions of the material .

For example, deleterious warping may, however, appear in turbulence sheets according to the prior art and made from essentially one piece. As a result, the sheet can no longer be considered to be an essentially flat plate, and may instead have, for example, wave-like formations over at least part of its area. Warping will lead, for example, to disturbances in the discharging slice jet. Another drawback associated with elements according to the title is that known turbulence sheets are very cost-intensive. If the sheets intended for a headbox are of, for example, a composite material, the purchase and possible length varying will represent a considerable cost for the paper manufacturer. A figure of up to € 50 000 / paper machine is an example of the capital tied up in sheet wedges.

Sheets can break or usually simply wear out, as a result of which they must be replaced at intervals. The need for replacement may come one's way unexpectedly, in which case it is impossible to estimate the need beforehand. A cost-intensive store of sheets is in all ways inappropriate from the paper manufacturer's point of view.

Yet another drawback, concerning particularly wedge-shaped sheets, relates to a type of headbox developed by the applicant and also known by the name OptiFlo (Figure 5) . In it, a wedge-shaped sheet 10 ' shown by the broken line is attached through a pivot 16 in connection with the openings at the output end of the turbulence generator. Due to the narrowing nature of the standard composite wedge 10 ' used in the headbox in question there is a pocket 19 in the pivot area 16, into which the composite wedge 10' fits. As is quite obvious from Figure 5 showing the prior art, in the arrangement of this kind it is not possible to use the normal non-wedge-shaped plastic turbulence sheet 10' ' (shown in Figure 5 with a solid line), instead of a particular OptiFlo wedge 10' developed precisely for this headbox. This is because due to the even thickness throughout the sheet 10" would result in the formation of a dirt-collecting pocket-like and open recess 18.1, 18.2, 19 in the pivot area 16. When detaching from the pocket 18.1, 18.2, 19, the dirt will cause serious runnability problems. Finnish patent application 20001404 and German patent publication DE 196 52 981 Al are referred to as prior art of the turbulence sheets .

The intention of the present invention is to bring about a turbulence element for the headbox of a paper machine or similar, which has improved shape-constancy properties and is also suitable for use as a spare sheet in different types of headbox. The characteristic features of the turbulence element according to the invention are stated in Claim 1. The invention also concerns a method for manufacturing a turbulence element. The characteristic features of the method are stated in Claim 9.

The turbulence element according to the invention is formed of a base structure that widens into the slice channel area and reinforcements fitted in connection with it. An attachment member and a tip part are fitted to the base structure. The reinforcements, which are in the area between the attachment member and the tip part, are fitted to the top and bottom of the base structure .

According to a first embodiment, the reinforcements on both sides can be situated on the turbulence element in connection with, or in the vicinity of the edge of the element that is attached to the output end of the turbulence generator. The reinforcements can form their own separate flat plates, which can be essentially separate from the attachment members of the element, by means of which the element is installed, for example, through a pivot in connection with the end of the generator, more generally in the frame of the headbox.

According to a second embodiment, the reinforcements can cover only part of the base structure. In that case, they can extend in the machine direction over, for example, 5 - 25 %, such as, for example, 15 %, of the area of the base structure of the turbulence element while in the cross direction of the machine they cover mainly the entire base structure. In the cross direction, the reinforcements can be formed of one, or even of several pieces .

According to one embodiment, the combined thickness of the reinforcements and the base structure can be such that a substantial step is not formed between the element and the tube opening from the end of the turbulence generator. The basic thickness of the reinforcements can be, for example, 1 - 6 mm, such as 2 - 4 mm while the basic thickness of the base structure can be 1,5 - 5 mm, such as, for example, 3 mm. In certain types of headboxes, in which there are protrusions creating a pocket-like formation at the attachment point of the element, these pockets are filled by means of such a construction formed of several components. This will bring the advantage of reducing dirt collection to these annoying pockets that would otherwise remain open when using a "standard sheet" .

The reinforcements can also be wedge-shaped in the flow direction of the headbox. In that case, they connect with the base structure of the turbulence element smoothly and will not collect dirt.

The turbulence element according to the invention can be applied in numerous different types of web-forming machines and headboxes . The solution according to the invention can also be used in a multilayer headbox, to separate two mass suspensions with different compositions from each other. Some examples of these web-forming machines include not only paper machines, but also board machines, tissue machines, and pulp machines. The manufacturing procedure based on the method according to the invention is also simple. It can be use to create general-purpose turbulence elements, which can be used, for example, as spares for the proper elements. Other additional advantages achieved by the invention appear in the description portion and the characteristic features form the accompanying Claims .

The invention, which is not restricted to the embodiments described in the following, is examined in greater detail with reference to the accompanying drawings, in which

Figure 1 shows a cross section of the headbox, equipped with sheets, of a paper machine, Figure 2 shows an enlargement of a headbox when applying sheets according to the invention, Figure 3 shows the sheet of Figure 2, together with its holder, Figure 4 shows a sheet seen from different directions, and Figure 5 shows examples of sheets, according to the prior art, in a holder.

Figure 1 shows part of an as such conventional headbox 11 of a paper or board machine. The headbox 11 of the paper machine can be formed a several consecutive sub-assemblies, all of which need not be examined, or even itemized in this case. The headbox 11 includes a turbulence-generator section 12 arranged consecutively in the flow direction of the paper machine, i.e. in the machine direction, and the slice-channel area 13 following by that. As is known, the mass, which contains water, used in the manufacturing process is fed through the turbulence generator 12 to the slice chamber 13.

The turbulence-generator section 12, which can be formed of one or more sub-sections (not examined in greater detail) , comprises two ends in the flow direction. The mass flow is brought to the first of these (not shown) from the headbox section preceding the generator 12 while from the other end 12.2 it discharges from the generator 12 to the slice channel 13. This second end 12.2 can also be called the output end of the slice-channel 13 side. Using the turbulence generator 12 the fibres of the mass are tried to separate from each other and oriented at randomly as possible relative to each other.

In this case, the turbulence generator 12 is formed of several pipes/tubes 22, which are supported by supportive plates 23 and 24 on both ends 12.2. Openings 25, into which the tubes 22 are set, are machined in the plate at the output end 12.2 bounding the slice chamber 13. Seen from the output end 12.2, the tubes 22 are generally rectangularly shaped, at which the turbulence generator 12 terminates. In Figure 1, the tubes 22 are in seven rows on top of each other, which extend over the whole width of the headbox 11. The tubes 22 can be set at a certain angle relative to each other, in such a way that the flows discharging from the tubes of the various rows combine in the slice-lip opening 27. Figure 1 does not, however, show the mass or its flows.

After the turbulence generator 12 in the slice chamber 13 there is one or more turbulence plates 10, by means of which the desired level of turbulence is maintained up to the slice-lip opening 27 and even as far as the wire section. The mass discharges from the slice-lip opening 27 onto the wire carried by the roll T and is carried onwards by it.

In the headbox of Figure 1, there are six turbulence plates 10, and each of which may be of a type manufactured according to the method of the invention. The plates 10 are in connection with the ends 12.2 of the tubes 22, particularly at at least some of their boundary points, more generally in the frame of the headbox 11. The sheet 10 spread over the slice channel 13 or a group of sheets 10 on top of each other are used to cover most of the slice channel 13. The sheet 10 is attached to the boundary point in such a way that it can be replaced. The sheet 10 can have a mainly flat geometry. Its width in the cross direction of the machine can be, depending on the production width of the machine, for example in the order of 8 - 12 metres and its length in the machine direction, for example 300 - 1000 mm, generally 500 - 700 mm. It should be noted that Figure 1 is intended to illustrate at general level the headbox 11 and the sheets 10 arranged in it. The construction of a sheet 10 according to the invention is shown in greater detail in Figures 2 - 4.

For the attachment of the sheet 10, there is a suitable clamp 16 on one edge at the end of the turbulence plate 10 and in the plate 24 bounding the slice chamber 13, which can be understood as the frame of the headbox 11, being, for example, a groove 17. In connection with one edge of the sheet 10, there can be attachment members 16 for attaching the sheet 10 to the output end 12.2 of the turbulence generator 12. At the edge opposite to the attachment edge of the sheet 10, is the tip part 20 of the turbulence element. The groove 17 located in the boundary- area between the openings 25 can be parallel to the transverse direction of the headbox 11 and unified. In this case, the clamp 16 is formed by a hinge element permitting turning of the turbulence plate 10. Such an arrangement is easy to manufacture and turbulence plate 10 it creates has a sturdy construction.

Figures 2 - 4 show one example of the construction of a turbulence element 10, according to the invention, that is arranged, or can be arranged in connection with the headbox 11 of a paper or board machine or similar, and of a headbox 11, in which such turbulence element 10 can be applied, according to one embodiment, at the exhaust end 12.2 of a turbulence generator 12. In the following, the turbulence element will be referred to by using the expression sheet 10. Despite this, the characteristics shown are applicable to all turbulence plates.

In the invention, at least some of the sheets 10 in the slice channel 13 are formed of a base structure 14 spread into the slice channel 13 and of reinforcements 15.1, 15.2 arranged on top of and underneath it. In the base structure 14 there is an attachment member 16 and a tip part 20. The reinforcements on top and bottom of the base structure 14 are in the area between the attachment member 16 and the tip part 20.

According to one embodiment, the reinforcements 15.1, 15.2 are in connection with one edge 10.1 of the turbulence element 10, in such a way that they are essentially separate from the hinge component, i.e. the attachment members 16. The attachment

) members 16 can otherwise be formed quite freely and is not examined further in this connection. The attachment member can be, for example, a rod 16 attached to the edge 10.1 of the sheet 10, and which can be partly embedded in the base structure 14 of the sheet 10. Other types of attachment too i can, of course, be considered. Using attachment members 16 separate from the reinforcements 15.1, 15.2 makes them easy to adjust and permits a quick-release attachment.

The reinforcements 15.1, 15.2 can cover 5 - 25 % of the flow i direction of the headbox 11, such as, for example, 15 % of the total length of the turbulence element 10 in the machine direction. A greater coverage in the machine direction is also possible, but it will not necessarily have substantial advantages. In the case according to Figure 4, the entire machine-direction length of the sheet 10 is 350 mm while its width is 8000 mm. In that case, the machine-direction length of the reinforcements can be, for example 50 mm while their width mainly corresponds to the total width of the sheet 10. As can be seen from Figure 4, the reinforcements 15.1, 15.2 do not extend quite to the end 10.1 of the sheet 10, but instead remain slightly short of it (about 7 mm) . The clamp 16 is clearly separate from the reinforcements 15.1, 15.2 and forms its own construction attached to the base structure 14.

The combined thickness of the reinforcements 15.1, 15.2 and the base structure 14 is arranged to be such that there is essentially no step between the element 10 and the tube 22 at the end 12.2 of the turbulence generator 12. If such appears, it will be in the order of magnitude of a few millimetres, i.e. the thickness of the wall of the tube 22 of the turbulence generator 12. The basic thickness of the reinforcements 15.1, 15.2 will then be 1 - 6 mm, for example 2 - 4 mm, while the basic thickness of the base structure 14 will be 1,5 - 5 mm, for example 3 mm. In the example of Figure 4, the thickness of the reinforcement is 3 mm and the thickness of the base structure 14 is also 3 mm. This results in the thickness of the entire sheet 10 in this embodiment becoming about 9 mm in the area covered by the reinforcements 15.1, 15.2.

The reinforcements 15.1, 15.2 are arranged to join smoothly with the base structure 14 of the turbulence element 10, the end 10.2 opposite to the output end 12.2 of the turbulence generator 12 being more the end at the side of the tip part 20 than the attachment end 16. The use of such a step-free formation avoids, for example, dirtying. The reinforcements 15.1, 15.2 can also be polished, which will further deduce not only sensitivity to dirtying, but also friction. The base structure 14 of the sheet 10 can also be narrowed to be wedge-shaped in the flow direction at the end 20 and to terminate in a sharp tip. The thickness of the tip can be, for example, in the range 0 - 2 mm, for example less than 1 mm.

As can be clearly seen from Figure 3, in the embodiment shown in it there are counter members 17 in connection with the output end 12.2 of the turbulence generator 12, more generally in the frame of the headbox 11, which in this case are arranged to enclose the attachment member 16 of the turbulence element 10 inside themselves. In the counter member 17 there are now protrusions 18.1 and 18.2, which, together with the counter member 17, form a pocket-like shape 19. In this case, the reinforcements 15.1, 15.2 are arranged to have dimensions such that they close and fill the pocket 19 when arranged in the base structure 14. As a result, dirt will no longer collect in the "foxhole-like" pocket 19, which would interfere with the functioning of the hinging 16, 17.

In addition to the sheet, the invention also relates to a method for manufacturing the sheet 10. As one stage in the manufacturing process of the sheet 10, the reinforcements 15.1, 15.2 are attached to the top and bottom of base structure 14 of the sheet 10 in the area between attachment means 16 and the tip part 20. One method of attachment is gluing.

The use of the invention achieves many different advantages. The sheet 10 can be of almost any material at all. Besides a composite material even plastic (for example, polycarbonate PC) can be used, both as the reinforcements 15.1, 15.2 and/or as the base material 14. According to one embodiment, in the solution according to the invention it is possible to use a metal, for example steel or titanium, as the base structure 14 of the turbulence element 10, and a thermoplastic as the reinforcement 15.1, 15.2. This will achieve a rigid and durable turbulence element 10 with low manufacturing costs.

If an actual spare wedge is lacking, the sheet 10 according to the invention can be used as a makeshift. Of course, the sheet 10 can also be applied as an actual sheet without any particular "spare-sheet status". Thus the paper manufacturer will not need to maintain a capital-intensive store of sheets, for which expensive spare sheets would have to be purchased. Plastic is an advantageous material in other ways too, because it is considerably cheaper than, for example, a composite material. In addition, the length of the sheet 10 can be easily varied, because the base structure 14 can be easily machined and the reinforcements 15.1, 15.2 are at the opposite end 10.1 to the tip part 20. It must be understood that the above description and the related figures are only intended to illustrate the present invention. The invention is thus in no way restricted to only the embodiments disclosed or stated in the Claims, but many different variations and adaptations of the invention, which are possible within the scope on the inventive idea defined in the accompanying Claims, will be obvious to one versed in the art.

Claims

1. Turbulence element (10), which is exchangeably fitted in the area of the slice channel (13) of the headbox (11) of a paper i machine or similar, the turbulence element (10) comprising an attachment member (16) and a tip part (20) and in which the attachment member (16) is connected to the frame structure (24) of the headbox (11) , characterized in that the turbulence element (10) is formed of

- a base structure (14) , to which the said attachment member (16) and tip part (20) are fitted and

- reinforcements (15.1, 15.2) fitted to the top and bottom of the base structure (14), and which are fitted in the area between the attachment member (16) and the tip part (20) .

2. Turbulence element (10) according to Claim 1, characterized in that the reinforcements (15.1, 15.2) are fitted in connection with the end of the turbulence element (10) nearest the attachment member (16) , in such a way that they are essentially separate from the said attachment member (16) .

3. Turbulence element (10) according to Claim 1 or 2, characterized in that the reinforcements (15.1, 15.2) cover 5 - 25 %, such as, for example 15 %, of the total length of the turbulence element (10) in the machine direction.

4. Turbulence element (10) according to any of Claims 1 - 3, characterized in that the combined thickness of the reinforcements (15.1, 15.2) and the base structure (14) is arranged to be such that essentially no step is formed between the turbulence element (10) and the tube (22) at the end (12.2) of the turbulence generator part (12) .

5. Turbulence element (10) according to Claim 4, characterized in that the basic thickness of the reinforcements (15.1, 15.2) is 1 - 6 mm, for example 2 - 4 mm and the basic thickness of the base structure (14) is 1,5 - 5 mm, for example 3 mm.

6. Turbulence element (10) according to any of Claims 1 - 5, characterized in that the reinforcements (15.1, 15.2) are arranged to join smoothly to the base structure (14) of the turbulence element (10) at the end (10.2) nearest the tip part (20) .

7. Turbulence element (10) according to any of Claims 1 - 6, which can be connected by the attachment member (16) to the frame structure (24) of the headbox (11) , to which frame structure (24) counter members (17) are fitted, which are arranged to enclose the attachment member (16) of the turbulence element (10) within themselves and in which counter member (17) there are protrusions (18.1, 18.2), which form a pocket-like shape (19) with the counter member (17), characterized in that the reinforcements (15.1, 15.2) are arranged to close/fill the said pocket (19) .

8. Turbulence element (10) according to any of Claims 1 - 7, characterized in that the reinforcements (15.1, 15.2) are glued to the base structure (14) .

9. Method for manufacturing a turbulence element (10) used in the headbox (11) of a paper machine or similar, in connection with one side of the element (10) there are attachment means

(16) for installing the turbulence element (10) in the headbox (11) and a tip part (20) of the turbulence element (10) in connection with the opposite side, characterized in that the turbulence element (10) is manufactured by attaching reinforcements (15.1, 15.2) to the top and bottom of the base structure (14) in the area between the attachment means (16) and the tip part (20) .

10. Method according to Claim 9, characterized in that the reinforcements (15.1, 15.2) are attached to the base structure (14) by gluing.