FI67106C - TURBULENSGENERATOR FOER INLOPPSLAODA TILL EN PAPPERSMASKIN DESS FRAMSTAELLNINGSFOERFARANDE OCH MED IFRAOGAVARANDE TURBULENSGENERATOR FOERSEDD INLOPPSLAODA TILL EN PAPPERSMASKIN - Google Patents

Description

67106

Paper machine headbox turbulence generatorl, its manufacturing method and paper machine headbox equipped with that turbulence generator

Turbulensgenerator för inloppsläda account en pappersmaskin, dess framställningeförfarande och med ifragavarande turbulensgenerator försedd inloppsläda account en pappersmaskin

The invention relates to a turbulence generator for a paper machine headbox, which is arranged between a compensating chamber in the headbox pulp suspension flow channel, a manifold or the like and a wall cone part or the like in the headbox to generate a counterpart such as a structural load-bearing part between the lower wall and the upper wall, and wherein the turbulence generator has a lattice or grating part made of plastic or the like having a wider reference pedal surface directly connected to said load-bearing perforated plate.

The invention further relates to a method of manufacturing a turbulence generator for a paper machine headbox.

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The invention also relates to a paper machine headbox provided with said turbulence generator.

With regard to the state of the art related to the present invention, reference is made to FI patent No. 50 260 of 20 applicants. This patent discloses a headbox having a manifold part after the manifold, then a so-called intermediate chamber part, followed by a lamella part followed by a lip cone part. According to said patent, the lamella part consists of a plurality of adjacent lamellae oblique to the vertical plane, which delimit turbulence channels with a trapezoidal cross-section.

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The headbox solution disclosed in the above-mentioned F1 patent has proved to be advantageous in operation, but one disadvantage is the high cost of its structure, in particular the lamella part. Another disadvantage is that such a headbox has a fixed structure, and thus in paper machines equipped with such a headbox it is not possible to substantially change the production quality or fine-tune the characteristics of the headbox according to the particular paper grade or pulp grade.

10 Applicant's earlier Finnish patent applications Nos. 800018, 801167 and 801854 disclose certain cassette headbox solutions which have specifically sought to ensure that the parts of the headbox mass suspension flowing through the flow channel are interchangeable cassette parts so that the headbox is interchangeable. conditions. Thus, the structure of the headbox can be quite easily changed when the production quality is changed. This design also makes headbox maintenance and cleaning even easier.

The closest prior art to the present invention is apparent from Applicant's FI Patent Application No. 822287 (filed June 28, 1982), which discloses a headbox equipped with a paper machine turbulence generator, the turbulence generator consisting of a perforated plate acting as a bearing part for the headbox between the parts, and a grate part composed of a cell element comprising a plurality of overlapping and 25 parallel flow channels, which elements are arranged in the transverse direction of the headbox several in parallel. The structure of said grate part is such that, under its control, the flow channel of the pulp suspension in the flow direction is expanded from the tube flows of the channels of said perforated plate to a flow having a wider square cross-section of the lip cone part.

EN-pending Applications. The grating part used in the turbulence generator according to No. 822287 can be assembled from several sub-elements, which can preferably be made of plastic, e.g. by injection molding. In particular, the grating-35 part, possibly also the perforated plate, can be easily replaced. According to the latter F1 application, the parallel flow channels of the grate part expand in the direction of flow of the mass suspension from the circular polygonal surface 3 67106 holes to rectangular transverse, parallelepiped or polygonal, also to have section.

The turbulence generator according to FI application No. 822287 is composed of sub-elements fastened to said perforated plate with screws, the height of which corresponds to the vertical dimension of the flow channel of the pulp suspension. There are several sub-elements in parallel in the transverse direction of the headbox.

An advantage of the headbox disclosed in the above-mentioned F1 patent application No. 822287 can be considered to be that the perforated plate part after the leveling chamber acts as a load-bearing part between the upper and lower lip structures of the headbox, receiving relatively large forces, especially due to the pressure load of the pulp suspension.

However, a disadvantage of the latter known structure is that said perforated plate must generally be made of expensive acid-resistant steel and its surfaces, including the inner surfaces of the flow holes, must be finished very smooth. In general, these surfaces must be electrolytically polished to prevent the formation of fiber bundles that collect and interfere with flow. A disadvantage of the above structure is also that the perforated plate and the plastic grating part have to be fastened to each other with screws, the bases of which and the seams between said parts form discontinuities which thus collect the fiber bundles and thus interfere with the turbulence generator.

It is therefore an object of the present invention to provide a novel headbox turbulence generator, a method of manufacturing the same, and a headbox equipped with said turbulence generator, which does not exhibit the disadvantages discussed above.

It is a particular object of the present invention to provide a turbulence generator and a method of manufacturing the same, in which the shape of the flow channels of the turbulence generator can be easily adjusted to be optimal for microturbulence generation and such that said shape 67106 can be easily varied e.g.

A further object is to provide a turbulence generator and a method of manufacturing the same, in which the turbulent generator can be composed of even cheaper materials and in which, however, the surfaces in contact with the mass suspension flow are made sufficiently smooth by simple manufacturing methods.

It is also an object to provide a turbulence generator in which plastic parts with such thin walls can be used that changes in the thermal deformation of these parts do not adversely affect the operation of the turbulence generator.

In order to achieve the above and later objects, the turbulence generator according to the invention is mainly characterized in that the turbulence generator is composed of polarly adjacent parts of a paper machine. a plastic coating which is 20 identical integral pieces with said lattice or grating part.

The method of manufacturing a turbulence generator according to the invention, in turn, is mainly characterized in that the turbulence generator element is manufactured by injection molding by placing the pre-perforated a casting space into which the plastic-30 coatings of said perforated plate are formed from the plastic fed through the casting channel and said lattice or grating element with the perforated plate into one integral turbulence generator element.

The headbox of a paper machine provided with a turbulence generator according to the invention is mainly characterized in that a turbulence generator is arranged between the balancing chamber and the lip cone part of the headbox 35. the elements are according to any one of claims 1 to 5 and / or are produced by a method according to any one of claims 6 to 8.

In the following, the invention will be described in detail with reference to an embodiment of the invention shown in the figures of the accompanying drawing, to the details of which the invention is in no way narrowly limited.

Figure 1 shows a machine direction vertical cross-section of a headbox according to the invention at its turbulence generator according to the invention. Figure 1 is at the same time section I-I in Figure 3.

Figure 2 is a schematic axonometric view of a turbulence generator according to the invention composed of adjacent sub-elements in the transverse direction of a paper machine.

Fig. 3 shows a part of the turbulence generator element seen from the direction B marked in Fig. 1.

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Figure 4 shows the same as Figure 3 in an alternative embodiment.

Fig. 5 shows a part of the turbulence generator element seen from the direction A shown in Fig. 1.

Fig. 6 illustrates a method of manufacturing a turbulence generator according to the invention, and Fig. 6 shows a cross-section of an injection mold in which the plastic molding step of the turbulence generator 30 according to the invention takes place.

The headbox shown in Figure 1 shows the lower lip walls 10 and the upper lip 16 of the lip carton 18 fixed to the upper lip wall 11 by said horizontal joint 15. Said slide 14 joins the upper lip wall 11. A perforated plate 22 is provided as a structural body between the lower lip wall 10 35 and the upper lip wall 11. fixed with screws 12 to the lower lip wall 10 and with screws 13 to the upper lip wall 11.

6 67106 The relay plate 22 thus forms a structural body part »which receives, in particular, the pressure loads between the upper lip wall 11 and the lower lip wall 10 caused by the mass suspension flow, which cause a tensile load on the hole plate 22. The turbulence generator 20 and its hole-5 plate 22 are preceded by a compensating chamber 17, which in turn is preceded by a manifold which opens into the manifold. As is known per se, the equalization chamber 17 can be connected to an air chamber which dampens the pressure disturbances of the pulp suspension flow.

The entry of the pulp suspension to the turbulence generator 20 is illustrated by the arrows and the output from the turbulence generator 20 and the entry into the lip cone 18 by the arrows F, respectively.

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According to Figures 1-5, the turbulence generator 20 consists of the above-mentioned perforated plate 22 and the associated honeycomb part 26, two different embodiments of which are shown in Figures 3 and 4. According to Figure 1, the perforated plate 22 has a plurality of overlapping rows of flow openings 23 The hole plate 22 is covered on the side of the leveling chamber 17 by a plastic wall 28 which ends at the edge shoulder member 29. One piece of plastic with the wall 28 is the plastic backs 27 of the flow holes 23 of the hole plate 22 which extend through conical parts 24 into or 4 visibly honeycomb. The above-mentioned plastic parts 26, 27, 28 and 29 are one integral plastic piece molded in connection with a perforated plate 25 22 in a mold casting step according to the invention to be described later.

According to Fig. 3, the lattice portion 26 consists of a planar upper wall 31 and a corresponding lower wall 32, the latter coming against the inner surface of the lower lip 30, and the upper wall 31 coming tightly against the inner surface of the upper lip wall 11. According to Fig. 3, the lattice part 26 consists of honeycomb-shaped hexagons with equal walls delimiting flow channels 25, by means of which the flow from the flow openings 23 of the perforated plate 22 through the conical part 24 is expanded to flow in the lip cone 18. The opening angle of the conical part 24 in the direction of flow is e.g. about 90 ° or less. The largest dimension of the flow channels 25 of the gate part 26 is marked in Fig. 3b, which dimension is e.g. 2 to 4 times »most preferably about 3 times, the diameter d of the flow channel 23. According to Fig. 4, the flow channels 25 'of the grating portion 26' are sloping spaces inclined with respect to the vertical plane, having walls inclined with respect to the vertical plane determined by the shape of the hexagon, the direction 5 of which is determined by the rows of perforations 23

According to Figure 2, the turbulence generator 20 consists of a plurality of parts 20a and 20b connected to each other by a vertical seam 30. The edge element 20a may be provided with a planar vertical wall 20 "which abuts the vertical wall of the stern box body. The central portions 20b, which are several in parallel, may engage the edge portions 20a and a vertical seam 30, most preferably consisting of a vertical wall of a hexagonal cell 26 only. half the normal wall thickness of the cell in question so as to obtain an even hole distribution over the entire width of the turbulence generator 15.

The above-described parts 20a, 20b of the turbulence generator 20 are made according to the invention as follows. For example, in a mold 40 as shown in Fig. 6, a perforated plate 22 is placed, the width of which corresponds to the width of the sub-element to be manufactured. The perforated plate 22 is made of, for example, normal structural steel and holes for flow openings 23 are drilled in it with a suitable division. The surfaces of the perforated plate 22 may be traces of roughing. The injection mold 40 includes a mold body 41, an injection nozzle 42, a mold front portion 43, a center portion 44, and a rear portion 45 connected to each other by guides 48 25. The ejection is indicated by reference numeral 47. The water passed through the cooling water passages 49 controls the temperature of the mold 40 and thus the curing time and surface quality of the plastic parts 26,27,28,29 formed in connection with the perforated element 22. The flow channels 23,25 are determined according to the shape of the inner cores 46.

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The plastic molding step by means of the mold 40 is a technique known per se. With the shape of the cores 46, the shape of the flow channels of the turbulence generator 20 can be chosen quite freely to be optimal in terms of flow technology and microturbulence. The chamfer 24 is both flow-technically and 35 flow-technically advantageous, because the molten plastic flows through it better than in a steep step.

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Since the perforated plates 22 forming the supporting body portion of the turbulence generator 20 come from lime from the surfaces from which they come into contact with the earthenware brush, covered with a layer of plastic, the quality of the plastic molding surface determines the quality of the turbulence generator flow surfaces.

5 The surface quality of the plastic parts, in turn, is determined by the quality of the plastic raw material used, the quality of the pins 46 and the cooling time. By appropriately selecting said parameters, sufficiently smooth flow surfaces can be obtained for that purpose. The bevels and roundings of the various parts can also be controlled in the injection molding step 10 performed in the mold 40. Since the strength of the plastic coating 27,28 coming into contact with the metal sheet 22 is relatively small, deformations due to different coefficients of thermal expansion of the metal and plastic are not adversely affected, but the plastic layers 27,28 remain reliably "glued" to the perforated plate 22.

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The material of the plastic parts of the turbulence generator 20 is, for example, polyamide 12, with which a glass wool reinforcement material is used. As said, the outer surface of the cores 46 determines the shape and surface quality of the inner surface of the flow passages 23,25, and has the advantage that the cores 46 can be easily fabricated to be optimal for the mass suspension flow and the microturbulents generated therein. The invention also has the advantage that even with one and the same mold 40, all the different components of a turbo-lens generator can be manufactured. In this case, the planar side surfaces of the end elements 20a can be obtained by using a suitable filling piece 25 in the mold. By varying the diameter and shape of the cores 46, turbulence generators can also be made in the same mold for different mass grades.

It is also an advantage that the metal plate 22 can be made of an even cheaper material, e.g. instead of acid-resistant steel, stainless steel or even structural steel, which does not require other surface treatment steps after roughing. If, for example, narrower parts 20a; 20b are required due to the width of the paper machines, part of the mold 40 can be closed with a slip and thus suitable sub-elements can be produced. 35

The following are claims within the scope of which the various details of the invention may vary within the scope of the inventive idea.

Claims (9)

1. Turbulence generator (20) for the inlet drawer of a paper machine, such as Mr. fitted between the ejecting chamber (17) 1 of the pulp suspension flow channel 1 in the inlet drawer, the distributing stock or corresponding and the inlet drawer's conformal impeller portion (18) or corresponding the pulp suspension stream and which turbulence generator (20) comprises a housing plate part (22) of steel or the like, which acts as a structural part which receives loads between the opposite walls of the inlet pulp pulp suspension flow channel, such as the under wall (10) and the overburden ( a damper or lattice portion (26) adjacent to said load carrier plate (22) having a wider flow cross-section and Mr. face of the plate or the like, characterized in that the turbulence generator has been assembled by adjacent portions (20a). , 20b) in the cross-section of the papermaker, in which parts said damper or grating portion 15 ( 26) assembled with the holding slab (22) is of a single integral piece in such a way that said holding plate (22) At least on its flow surfaces has a plastic cover (27,28) which belongs to each unitary piece together with said damper or grid part (26). Turbulence generator according to claim 1, characterized in that in said damper or grating part (26) there are planar gable surfaces (20 ", 31,32) which meet the walls of the inlet casing which are adjacent to the conical lip part ( 18). Turbulence generator according to claim 1 or 2, characterized in that said damper or lattice portion (26) has a cellular structure which joins from said pulp suspension flow arrival side (F)) to said supporting holding plate (22) and the tubular plastic cover d. e. lamella (27) of its elongate flow channels (22) by means of a conical portion (24) or the like, which in turn joins the plastic wall (28) of said front wall (22). Turbulence generator according to claim 1,2 or 3, characterized in that the upper and lower sides of said holding plate 35 (22) are free of plastic cover and, most preferably by means of a screw connection (12, 13), by means of a screw connection (12, 13). said shelf disk (22) is fixed to the inlet & dance lower and upper walls (10,11), most preferably 1 of the splice space or spaces thereof. Turbulence generator according to any one of claims 1-4, characterized in that the vertical sides of the turbulence generator parts (20a, 20b), with each of the widely spaced parts (20a, 20b) are joined together, consist of 1 mutually matching spar burst surfaces, which determine the shape of the walls of the flow channels (25) of the damper or grating elements (26). Preparation process for turbulence generator according to any of claims 1-5, characterized in that the turbulence generator parts (20a; 20b) are prepared by the injection molding method, by placing a finished perforated neck split part (22) in a plastic mold (40). a fixed position and, by the heel of said shelf member (22), to an extension of said casting cores (46), which together with the inner surfaces of said mold (40) and said shelf member (22) determine the casting space, select each plastic cover (27,28,29 ) for said heel plate (22) is formed from the plastic measured through the casting channel (42) and said damper or lattice element (26) together with the heel plate is formed into an integral turbulence generator element. 7. A method according to claim 6, characterized in that said neck split part (22) is made of stainless steel, structural steel or the like and that in said neck split part (22) drills shark with a suitable distribution and that the surfaces of said half disk part (22) ) are left in the condition they have after the roughing or the equivalent. 30 8. The inlet carriage of a paper machine, which is provided with a turbulence generator, characterized in that a turbulence generator (20) is arranged between the inlet carriage equalization chamber (17) and the conical lip part (18). 1, the transverse direction (20a, 20b) of the paper machine, which interconnected with each other by means of a seam (30), and that said parts (20a, 20b) are in accordance with some of the patent claims.